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357 Cards in this Set
- Front
- Back
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What is Diffusion? |
Movement of molecules from low to high Conc |
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What is Advection? |
Movement of materials through liquid form |
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What do arteries and veins do? |
Arteries move blood away from the heart andVeins move blood towards the heart |
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How do arteries and veins branch or connect? |
Small Veins branch into larger veins and largediameter arteries branch into smaller diameter arteries |
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What is the design of the mammalian cardiovascular system? |
The heart is 4 chambered and the blood flow is uni-directional |
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What does it mean when circuits are in series? |
Blood ends up in different sections one after another ensuring that all blood flows through the lungs then flows through the systemic circuit and to all organs |
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What does it mean when circuits are in parallel? |
Blood goes from heart to the brain and back to the heart not heart to brain to organs then back to the heart. Arterial bloodflow divides as it flows away from the heart and all organs receive oxygenated blood that has left the lungs |
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How is one-way blood flow achieved? |
Heart valves and Venous Valves |
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What is the equation for Haemodynamics? |
Flow=Pressure/resistance (Q=P/R) |
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How is pressure difference achieved? |
There must be high pressure on one side and low pressure on the other side |
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Why must the arteries be in high pressure? |
Because the blood in the system is in paralleland it keeps the blood in one direction |
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Systemic and pulmonary circuits move the blood in what? |
Series |
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Individual organs and tissue receive blood in? |
Parallel |
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What consist of the cardiovascular system? |
Heart, arteries, veins, capillaries etc |
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What are vascular tissues made up of? |
Connective tissues and epithelial cells ormuscles cells (smooth and cardiac) |
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What is the only muscle type is only unique to the heart? |
Cardiac Muscle |
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What does the heart do? |
Pumps blood around the body |
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What do the arteries and the veins do? |
Arteries are the supplying network and itsupplies capillaries to facilitate exchange. The Veins are involved with drainage. It drains fluid away from the tissues towards the heart |
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What organs make up the cardiovascular system? |
Heart, arteries, veins, lymphatics, and capillaries |
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What are vessels made out of? And what type of cells can you find within them? |
The vessels are called vascular tissues and aremade up of connective tissues. The cells can be either epithelial cells ormuscle cells |
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Where are cardiac and smooth muscles found? |
Cardiac muscles are only found in the heartwhereas smooth muscles are foundeverywhere in the body |
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What is the main function of the heart? |
Main function is to act as a pump |
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What is the function of the arteries? |
They are involved in supply. They are the onlysupply vessels in the body and supply capillaries facilate the exchange |
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What is the function of the veins/lymphatics? |
To drain the body. They drain fluid away fromthe tissues towards the heart |
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What is the function of capillaries? |
They are the exchange surfaces. The capillary beds perform exchange in the surfaces and drains fluid back to the heart |
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What is the blood vascular system (BVS)? |
It is closed supply and drainage system for the capillaries because it’s a continuous loop. Blood leaves the heart, to the tissues and back to the heart |
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What is the Lymphatic vascular system? |
It is a open entry draining system as it is aone way system. Fluid that leaves the BVS and builds up in the interstitual tissue space will drain back by the lymphatic system towards the heart as it reattaches to the BVS |
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What are the 3 general principlesof organisation in the cardiovascular system? |
Supply, exchange network and drainage |
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What are the supply vessels called? |
Arteries |
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What are arteries under? |
High velocity and high pressure |
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Where are the arteries situated and why? |
They are situated very deep in the trunk to avoid damage. Because they are under high pressure and high velocity, if they are pierced lots of blood can be lost quickly |
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What type of organs have more than one artery? |
The brain. Because they are very important andhas 2 separate arteries to supply it |
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How are arteries named? |
As they branch off they have different namesdepending on where they are situated |
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Where is the exchange network? |
They are found in the capillaries in the capillary beds |
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Why do capillaries have different shapes? |
Capillaries can be changed structurally tochange their permeability. Sometimes we need leakier or tightly regulated control of exchange at capillary beds |
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What are the 3 structures of capillaries? |
Continuous, fenestrated and sinusoidal |
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Explain the structure of continuous capillaries |
They tight and controlled. They are the mostcommon and is continuous because the epithelial cells are a continuous cell barrier and form a continuous tube |
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Explain the structure of Fenestrated capillaries |
They are leaky and lined with endothelium. Theyalso have porous openings on the surface to make it leaky
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Explain the structure of sinusoidal capillaries |
They are the most leaky hence has very largeporous openingsare the most leaky hence has very largeporous openings |
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What are the vessels used for drainage? |
Veins |
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What are veins under? |
Low pressure and low velocity |
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What are the 3 pathways fordrainage? i.e. 3 types of veins/lymphatics |
Deep veins, superficial veins, lymphatics
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What are deep veins? |
They are found in the deep compartments of the tissues and lie next to the supply arteries but travel in opposite directions |
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What are superficial veins? |
They are found between the deep fascia and the skin in the superficial compartment. They are very common but doesn’t lie nextto an artery. i.e. elbow |
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What are lymphatics? |
Returns any fluid that leaves the blood vascular space back to the BVS and is found everywhere in the body. |
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What must be balanced concerning the blood? |
The supply and drainage must be balanced or else the limb may end up with more blood being supplied than being drained |
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What must be compensated concerning supply and drainage? |
Because arteries have high velocity and high pressure more blood is being supplied than draining so we have to compensate for this by having the cross sectional area of veins to be twice of that of arteries (to shift the same volume of blood/second) |
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What are the 3 types of blood vascular disorders? |
Coronary artery disease (Heart disease), Cerebrovascular disease (stroke), Peripheral Arterial Disease (lower limb amputation) |
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What is a Lymph vascular system disease? And what does it do? |
Spread of Metases (cancers). When a tumor in onesite spreads to another section of the body |
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Explain coronary artery disease |
The coronary artery is blocked which starves the heart of blood and oxygen. Causes Alchemic heart disease. |
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What artery supplies the heart muscle? |
Coronary artery |
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Explain Cerebrovascular disease |
The artery that supplies the brain is blocked off which causes Aschemic stroke |
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Explain Peripheral arterial disease |
The peripheral artery is blocked off |
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Explain the structure of the heart organ |
The heart is blunt and coned shaped and is the size of a closed fist. The pointy end is called the Apex and the broad end isthe base. |
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Where is the heart placed? |
It is found in the thorax in the mediastinum. The apex points towards the mid clavicular line betweent he 5th and 6th ribs in the intercostal space. This point is called the PMI (point of maximal impulse/apex beat). The heart is placed towards the left sideof the chest |
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What side of the lung has more volume? |
The left cavity has less volume compared to the right because of the heart |
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What are the 4 chambers of the heart? |
Right ventricle, left ventricle, right atria,left atria |
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What does the right atria do? |
It recieves de-oxygenated blood from theperiphery then passes it into the right ventricle |
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What does the right ventricle do? |
It recieves de-oxygenated blood from the rightatria and pumps the blood into pulmonary vein and into pulmonary circulationfor re-oxygenation |
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What does the Left atrium do? |
When the blood is re-oxygenated it enters thischamber and then the blood is oxygenated via the pulmonary veins |
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What does the Left ventricle do? |
Recieves blood from the left atrium and thenpumps it into the aorta for systemic circulation |
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What separates the left and right chambers? |
The interventricular septum |
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Where does the Right atria receive blood from? |
Superior Vena Cava, Inferior Vena Cava, Coronary-sinus |
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Where does the left atria receive blood from? |
The 4 pulmonary veins. 2 left and 2 right. It receives oxygenated blood from the exchange capillaries |
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What area of the body does the superior vena cava drain? |
Drains all veins above the diaphragm. Neck, head and chest |
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What area does the Inferior vena cava drain? |
Drains all veins below the diaphragm |
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What area does the coronary sinus drain? |
Drains blood from the heart muscle itself
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How many layers in the heartwall? |
3 |
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What are the 3 layers of the heart wall? |
Endocardium, myocardium and epicardium |
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Describe the Endocardium |
Is the layer within and closest to the ventricular chamber. Has layers of squamous epithelial cells which sits on Loose irregular FCT. Has purkinje fibres and small blood vessels.
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Describe the Myocardium |
Is the layer within and is the thickest part ofthe wall. The myocardium on the left side of the heart is thicker than the right side. |
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Why is the left side of the heart thicker than the right? |
3:1 ratio. Because the left has more musclewhich means more force to push the blood to body parts whereas the right onlyhas to push to the lungs (pulmonary artery) which is a short distance thus thesmaller size. |
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Describe the Epicardium |
Is the outer layer and has a visceral serous pericardium, blood vessels, loose FCT and adipose tissue |
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What is the heart wrapped by?And why is it there? |
Pericardium which is a sac that provides lubrication and protection for the heart to prevent abrasions during heart beats. |
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Describe the structure of the pericardium |
It has a parietal layer of serous pericardium, pericardial fluid (cavity) and has a visceral pericardium/fibrous pericardium which is very strong has it has densely packed FCT |
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What is the difference betweenthe atrial and the ventricular chamber? |
Atrial= receiving chamber Ventricle=pumping chamber |
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What prevents blood backflow? |
Valves
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What are the 2 valves? |
Atrioventricular and semi-lunar valves. |
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How many valves do we have between the chambers?
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2 on the left and 2 on the right
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What is the function of the atrioventricular valves?
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To prevent the blood to return to the atria during ventricular contraction.
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How many atrioventricular valves do we have?
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We have 2. One on the left and one on the right. They are found in between the atria and the ventricle
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What type of atrioventricular valves are found on the left side of the heart?
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The Bicuspid or Mitral valve. Which has 2 leaflets
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What type of atrioventricular valves are found on the right side of the heart?
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Tricuspid Valve. Which has 3 leaflets
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What is diastole and what happens to the valves?
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Diastole is also known as the filling phase so the valves are open
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What is systole and what happens to the valves?
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Systole is known as the contraction phase. The valves are closed due to the pressure of blood
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What are the 3 structures that are involved with valves?
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Papillary muscles, chordae tendinae and the AV valve leaflet
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What are papillary muscles?
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They are finger-like projections of muscle that comes off the ventricular wall.
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Describe the structure of the papillary muscles
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There is one papillary muscle per leaflet of the AV valve. i.e. tricuspid has 3 papillary muscles. They do not pull the valve shut or open but they prevent the valve from slamming shut into the atrial chamber
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Describe the AV valve leaflet
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It is what the chordae tendinae attaches to
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Describe the chordae tendinae
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They are small strong tendons that attaches the papillary muscles to the leaflet. It is made up of FCT so is strong and prevents the valve leaflet from swinging around into the chambers
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What is the function of the semilunar valves?
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The function is to prevent blood from returning to the ventricles during diastole from their outflow chambers
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What are the 2 types of semilunar valves?
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Aortic and Pulmonary valves
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How many cusps do these 2 valves have?
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Aortic= has 3 and is on the left side
Pulmonary= has 3 cusps on the right side |
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What happens to the semi-lunar valves in relation to blood flow?
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When the blood flows out of the heart the valves open and when the blood back flows the valves close
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What is the difference between semi-lunar and atrioventricular valves?
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Semilunar valves deal with narrow openings so do not need strong structures like, papillary muscles or chordae tendinae as the blood flow can close them
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What artery supplies most of the lungs?
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Left pulmonary artery
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What does the left pulmonary artery branch into and what does it supply?
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It branches into the circumflex artery which supplies the left margin of the heart
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Where does the anterior interventricular artery run and where does it branch into?
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It runs anteriorly to the heart and branches into both sides of the heart but mostly to the left ventricle because it requires more blood
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What comes out of the aorta and what does it supply?
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The Right coronary artery branches to supply the right ventricle
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What does the great cardiac vein drain?
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The anterior interventricular artery and the circumflex artery
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What side of the heart does the small cardiac vein drain?
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Drains the right side of the heart
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What 2 veins unite to form the coronary sinus? And where does it drain?
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The great cardiac vein and the small cardiac veins and the cornary sinus drains into the right atrium
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What type of muscle is found in the heart?
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Cardiac muscle
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What the width of a capillary muscle?
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About the size of a RBC
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What is the function of the Cardiac muscle?
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To make the heart beat and keep it beating
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Describe the Cardiac muscle structure
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Striated, fat branched cells, 1 or 2 central nucleus, organelles packed at poles of nucleus,
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What is the only thing that cardiac muscles have?
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Intercalated disks
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How are neigbouring cells connected?
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Intercalated disks
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What is one organelle cardiac muscle needs lots of and why?
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Lots of mitochondria because it needs energy for the heart to continue beating
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Do cardiac muscles have sarcomeres and Z-lines?
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Yes
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What the 3 types of intercellular junctions that form intercalated disks?
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Gap, Desmosomes and Adhesion belts
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Describe adhesion belts?
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Link actin-actin. They tug with each other and stimulates contractions
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Describe Desmosomes?
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Link cytokeratin-cytokeratin. They stick cells together and prevents the cells from being pulled apart
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Describe Gap junctions
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They are for electrochemical communication. They also allows contraction to occur down cells continously
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What is the conduction system of the heart responsible for?
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The co-ordination of heart contractions and AV valve action. Closing/opening
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What alters the rate of conduction impulse generation?
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Autonomic nerves
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What are conduction pathways?
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They are modified cardiac muscles
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What are the 4 types of conduction pathways?
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AV node, SA node, Septal Branches and Purkinje Fibres
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Describe the AV (atrioventricular) node
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It is an area of tissue between the atria and the ventricles of the heart. It takes the signal from the SA node and slows the signal down and regulates it and then send the electrical impulse from the atria to the ventricles.
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Describe the SA (sinoatrial) node
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The SA is where conduction first begins in the right atrium. It recieves sympathetic and parasympathetic input which alters the input of the firing of the SA node.
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Describe the Septal Branches
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The AV node continues on to form the septal branches in the interventricular septum into the purkinje fibres
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Describe Purkinje fibres and what do they consist of?
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Purkinje fibres consist of peripheral myofibrils and are redundant. They have a central nucleus, mitochondria for conduction and has glycogen for energy. They have intercollated disks and lots of gap junctions but not many adhesion belts and actin sites
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What are the 3 veins of the lower limb?
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Common iliac vein (first split of the aorta), Femoral artey (groin to thigh), Femoral artery (groin to thigh), Posterior Tibial Vein (calf region)
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What are the veins of the lower limb?
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Posterior/anterior tibial vein, Femoral vein and the common iliac vein And the Great Sephanous Vein
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What is the great saphenous vein?
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It is an alternative route for blood to drain back. It is the longest vein in our body and runs in the superficial compartment just under the skin but not next to an artery and joins into the femoral vein
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What are the veins that drain the upper limb and thorax?
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Radial, brachial, median cubital vein, left subclavian vein, brachiocephalic vein, internal/external jugular vein, azygous vein and the superior vena cava
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What is the largest draining vein?
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The superior vena cava which drains into the right atrium.
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What does the Brachial vein join up with?
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Axillary vein
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What is the benefit of the Median cubital vein?
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It is not found where big arteries are so we can take blood samples in this area as there is a low chance of an artery being pierced
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What artery lies next to the radial vein?
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The radial artery
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Which vein drains below the clavicle?
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The Left subclavian vein and unites to from the jugular veins
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Which vein drains the head and neck?
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Brachiocephalic Vein
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Which vein drains into the brachiocephalic vein?
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Azygous vein
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What are the arteries that supply the upper limb and thorax?
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Brachiocephalic artery, subclavian, axillary, Brachial, Radial and Ulna artery
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Which artery supplies the head and neck?
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Brachiocephalic Artery
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Whar are the 3 layers of blood vessels?
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Tunica Intima, Tunica Media, Tunica Adventitia
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Which layer of blood vessels seperates the blood from the wall?
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Tunica Intima
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What is the structure of the Tunica Intima?
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It has lots of endothelium, a sub-endothelium and Internal Elastic lamina
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What lines the lumen of all blood vessels?
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A simple single layer of squamous epithelium which prevents blood clotting
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What is the sub-endothelium?
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It is a pad of loose FCT cushioning the endothelium
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What is the Internal Elastic Lamina?
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It is a condensed sheet of elastic tissue and is well developed in arteries and less developed in veins . It forms a barrier between the intima and the media
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What is the structure of the Tunica Media?
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It is made up of smooth muscle and is involuntary. It is surrounded by connective tissue fibres which is mainly elastin and collagen as a support matrix. Is the thickest part
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What is the significance of the Tunica media being thick?
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Thickness of the media is proportional to both vessel diameter and blood pressure that the vessel is trying to carry. Thicker wall means the vessel carries blood in high pressure
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Describe the structure of the Tunica Adventitia
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It has loose FCT, collagen and elastin. Larger vessels have a vaso vasorum but small ones don’t.
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What nerves are found in the Tunica media?
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Lymphatics and Autonomic nerves
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What is the function of the vaso vasorum?
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They are found in most large vessels and is a network of channels because large vessels also need blood vessels to supply it but small vessels don’t.
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What is the function of Arterioles?
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They are the very small resistance vessels of the circulation and is what determines blood pressure.
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What are the functions of capillaries?
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It is the site of exchange between blood and tissues. They are thin walled , has a large cross sectional area and is under smooth slow blood flow
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What are the functions of venules?
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Venules are thin, low pressure small walled vessels and is the start of the draining system. Has monocuspid valves
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What the functions of Veins?
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Veins are under low pressure, carries de-oxygenated blood and is a one way flow system back to the heart. They contain a lots of blood an
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Describe the structure of the veins
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They have lots of blood and has a thin media and a thick adventitia. It is flattened, irregular shaped with a large lumen and a thin wall thus they can collapse under their weight. Has lots of spare capacity so acts as capacitance vessels
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Describe the 3 layers of veins
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Tunica Intima (prevents blood clotting)
Tunica Media (Thinner than arteries. Has few layers of smoot muscle in 2 layers) Tunica Adventitia (thickest layer) |
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What is a vascualar bundle?
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Bundle of veins
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What is the consequence of poor drainage and supply?
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Varicose veins because the valves are dysfunctional
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Which structures do capillaries need to carry out exchange?
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They need to be thin walled, slow & smooth blood flow and have a large cross sectional area for the capillary bed for optimum gas exchange
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Explain the revelance of the total area in capillaries
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The larger the total area of the capillary bed means the slower the blood flow, compared to arterioles. Like a river flowing into the ocean. Arteriole flow (High blood flow) into a capillary bed (low blood flow)
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Which type of muscle doesn’t have striations?
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Smooth muscles
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What is the size of a capillary similar to?
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It is similar to the size of a RBC
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Which is the only muscle group with intercallated disks?
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Cardiac muscle
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What drains and supplies capillary beds?
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Venules (drainage), Arteriole (supply)
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What is the precapillary sphincter?
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Is smooth muscle that adjusts blood flow into the capillaries. It encircles the capillary at the point where the capillaries originates from an arteriole. It can open and close the entrance to the capillary
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What are the 3 types of capillary structures?
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Continuous, Fenestrated and Sinusoidal
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Describe the Continuous capillary (5-10um)
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It is the most widespread capillary and forms a continuos cellular barrier. It is controlled by precapillary sphincters and has a basal lamina which an extracellular connective tissue that has endothelium layed down
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Where in the body can you find continuous capillaries? musclewise
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Cardiac and skeletal muscle
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Describe Fenestrated capillaries? (5-10um)
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They are leaky as they have holes in the endothelium cells in which things can easily pass through the basal lamina
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Where can you find fenestrated capillaries?
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In the glormerulus and the kidneys
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Describe Sinusoidal capillaries (20-30um)
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They are not concerned with gas exchange. They are the most leaky and has a basal lamina that is not intact and is discontinuous. They have very big openings but RBC and WBC still can’t pass through
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Where can you find Sinusoidal capillaries?
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In the liver and the liver sinusoids
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What are the 4 functions of the lymph vascular system?
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1)Drain excess tissue fluid in the interstitual space back to the blood
2)Filters out foreign material from the lymph 3)Screens lymph for antigens and responds by releasing antibodies and activated immune cells |
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Describe the stucture of lymphatic vessels
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The commence as large blind capilliaries. Thery are thin walled and are under low pressure and large capillaries have valves to prevent backflow
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Describe the lymphatic vessel found in the small intestine
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The vessels are called lacteals. They drain fat laden lymph into the Cisterna Chyli then to the thoracic duct
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What section of the body drains from the right lymphatic duct into the right subclavian vein?
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Upper right body
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Which large lymph vessel drains the left upper body and lower body?
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Thoracic duct
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What is the start of the thoracic duct called?
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Cisterna Chyli
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What is the mucousal lining of the small intestine composed of?
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Villi which has a series of capillaries
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What are the 4 regional lymph nodes?
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Cervical, Axiallary, Inguinal and Cisterna Chyli
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Where abouts are these lymph nodes found?
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Cervical=neck, Axiallary=chest and inguinal=iliopsoas area
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List the direction of flow of lymph
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Fluid flows from tissues -> lymph vessels ->Lymph nodes -> veins ->target muscle
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Describe what can happen in the breast in regard to lymphatic drainage
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Breast tissue lymphatic drainage system can carry cancer cells into the blood vascualr system i.e. metastatic cancer
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The heart is 2 pumps that lie in what?
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Series
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What are the 4 steps for cardiac contraction?
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1)Increase in Cytosolic Ca2+ levels
2)Actin binding site revealed 3)A/M filaments slide relative to each other 4)Every myocyte is activated at each heart beat and every myocyte relaxes in each beat too |
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What happens when there is an increase in Cytosolic Ca2+ levels?
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Ca2+ induced Ca2+ release from the sarcoplasmic reticulum
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What happens when the actin binding site is revealed?
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The myosin binds forming the x/cross bridge
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What happens when the A/M slide over each other?
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The sarcomere shortens and there is a force generated
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Which side of the heart picks up oxygen and which side pumps it out?
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Right recieves the oxygen and the left pumps it out
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Why does the right and left sides of the heart contract simultaneously?
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Because if it is not in equilibrium the there will be a build up of blood on one side and not the other
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Describes the valves during contraction
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In contractions the valves are open/close to allow/prevent flow. The blood has a higher pressure when the valves are closed and each side of the heart is opposite of each other.
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What happens to the actin and myosin at rest?
|
Not interacting
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Why is calcium essential for contraction?
|
Calcium allows the muscle to contract. Small calcium induces a large calcium release which binds to troponin which allows the binding of actin and myosin aka cross bridge formation.
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What happens during each heartbeat?
|
Every cardiomyocyte is activated
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How do you increase the force of contraction?
|
You need to increase the amount of Ca2+, the # of cross bridges forming thus increasing the force of attraction
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Describe the celluar mechanism of cardiac relaxation
|
When the ATP binds to myosin, we must decrease the cytosolic Ca2+ level by putting it into the SR, which cause the X-bridges to be released and the A/M site to separate. All cardiac myocytes relax at each beat
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How are the cardiac muscles of the heart arrange and why?
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The cardiac muscle fibres are arranged in a helical pattern thus allowing maximum force of blood ejection. Like a wet towel- twisting
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What is the haemodynamics equation for blood flow?
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Flow = Pressure difference/resistance
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What is systole?
|
Is heart conrtractions. True systole is when the pressure in the heart reaches its highest point
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What is diastole?
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It is when the heart is relaxed and is under low pressure down to its minimum
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What are the 5 phases for the cardiac cycle?
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1)Atrial Systole
2)Isovolumetric ventricular contraction 3)Ventricular Ejection 4)Isoventricular relaxation 5)Passive Ventricular filling |
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What does isovolumetric mean?
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Means the valves are closed
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Describe Atrial systole
|
Moving blood into ventricles when atria contracts but valves are closed to prevent blood flow into aorta to increase pressure and volume of blood in the ventricle. So when it contracts we can get as much blood as possible.
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Describe Isovolumetric ventricular contraction
|
Atria are no longer contracting and the valve between atria and ventricle are closed as well as the aorta valves. So when heart contracts ventricle pressure increases but volume of blood stays the same because all valves are closed so there is more pressure build up.
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Describe Ventricular Ejection
|
When the aorta and the pulmonary artery valves open and blood flows through
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Describe Isovolumetric ventricular relaxation
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It is the opposite of the second phase. Almost all of the blood has left the ventricles with a little bit left. The ventricles relax and is under low pressure
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Describe Passive Ventricular filling
|
The heart passively fills with blood from the veins
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The heart spends more time in systole or in diastole?
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Diastole
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What is hypotension? (Low blood pressure)
|
When your body cant bring blood pressure back to normal or cant do it fast enough
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What is hypertension? (high blood pressure)
|
When your blood pressure is too fast and is too high
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What is the difference between the blood flow in arteries and the capillaries?
|
Arteries have pulsatile blood flow whereas capillaries have continuous blood flow
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What is the blood injection from the left ventricle into the aorta like?
|
It occurs at irregular intervals not steady
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What is the benefit of having the arteries to be elastic?
|
It means that the arteries can stretch and recoil thus storing and releasing energy
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When the blood is ejected out of the left ventricle a pulse wave is a what?
|
Is a pressure wave and travels along the arteries ahead of the blood
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Which pump left or right is more powerful?
|
The left pump is but the blood flows of both sides are the same
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Ventricular contraction leads to what?
|
Ejection of blood and pressurises the arterial system
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Whict chambers contract first?
|
The Atria contract before the ventricles
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Filling of the ventricles occur what?
|
Passively
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The cardiac cycle is defined by what?
|
By the contraction (systole) and relaxation (diastole) of the heart in a single heart beat
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How can pulmonary and systemic blood flow be equal when their respective pressures are different?
|
Pressure in systemic is higher than pulmonary as it needs more power but the flow is the same
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What are the 2 types of cells in the heart?
|
Contractile cells and electrical cells
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Describe the structure of contractile cells?
|
Is 99% of all cells in the body and has lots of actin/myosin and forms cross bridges to contract and is striated.
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Describe the structure of electrical cells
|
It makes up 1% of the cells in the body and the main purpose is to propagate electrical signals throughout the heart. It is striated and is found in the SA node and the Purkinje cells
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How do action potentials propagate down electrical and contractile cells?
|
They propagate along the surface membrane
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What is needed to occur at the SA node?
|
Depolarisation
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Do impulses spread to neighbouring cells? And how?
|
Yes the impulse spread to neigbouring cells. It moves along conduction cell to conduction cell/electrical cell and across to contractile cells
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What happens in a contractile cell?
|
Increased cytosolic Ca2+ levels, X-bridge attachment and contraction
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What connects most of the cells in the heart?
|
Intercalated disks and gap junctions. Can occur between both electrical cells and contraction cells
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What are gap junctions?
|
They are pores in cells with low resistance to ionic current. And allows current to flow between 2 cells
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How are impulses spread and which directions?
|
The impulses can be either passed along the conduction pathway, between electrical and contractile cells and also between contractile cells.
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Why do we want to spread the impulse?
|
To increase the speed of the impulse throughout the heart, to get the millions of cardiac cells to function as on
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What is the syncytium?
|
Present in both the atrial and ventricular areas of the heart. Is basically a network of cardiac muscle cells. The function of this network is to allow all of the cardiac cells to contract at the same time with only the slightest resistance
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Which node is also known as the pacemaker?
|
Sinoatrial Node
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What special ability does the SA node have?
|
It has the ability to cause the heart to beat and determines the normal heart beat and is the first site of signaling.
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What role does th SA node play in electrical impulses?
|
It sends out and electrical impulse win 3 directions and signals 2 atria to contract first.
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What role does the AV node play electrical impulses?
|
It stores the signal along the AV bundle so the atria can contract first up the walls of the purkinje fibres
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Describe how the left and right contracts simultaneously
|
First both the Atria contract and then both of the ventricles
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What is Depolarisation?
|
Contraction as the heart is being excited
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What is repolarisation?
|
Relaxation and the heart is being contracted
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What is Quiescence?
|
Means nothing has happened to the heart
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What is an ECG?
|
Electrocardiogram
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|
What is a lead?
|
Is a virtual line between 2 surfaces between 2 surface electrodes
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|
What does a single lead detect?
|
A single lead detects a difference between electrodes. Repolarization and depolarisation
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What are the 3 sections that make up a the ECG graph?
|
P, QRS and T-Wave
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|
What happens during the P wave?
|
Atrial Depolaristation and Atrial contractions
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What happens during the QRS complex?
|
Ventricular depolarization and ventricular contractions
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What happens during the T wave?
|
Ventricular repolarization and Ventricular relaxation
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What happens during a Ventricular contraction?
|
There is a rise in ventricular pressure and there is ejection of blood thus causing a fall in ventricular volume and there is a rise in aortic pressure
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What happens in the T-wave during ventricular relaxation?
|
Fall in ventricular pressure, the atrioventricular valves open and the ventricles begin to refill.
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What happens in atrial contraction?
|
Priming of the ventricles
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Which ventricle pressurises the systemic circulation? And how does is cause high pressure in the arteries?
|
Left ventricle through ventricular contraction and ejection of blood
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|
What is Mean Arterial Pressure (MAP)?
|
Is a major determinant of blood flow. It is the average blood pressure in an individual
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|
What is the blood pressure in arteries like?
|
There are high point (systolic) and low points (diastolic)
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What creates a driving force for blood flow?
|
The larger pressure difference between arterial and venous sides
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|
Why are there large pressure differences in ventricles?
|
Because ventricles need high pressure to push blood into the body.
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|
What is the pressure of the pulmonary artery like?
|
It is very low compared to other large arteries as they are under high pressure
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|
What type of vessel is under the least amount of pressure?
|
Veins
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Which vessels are the most tightly constrained?
|
Arteries because it must maintain high pressure
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|
What 3 things happen when blood flows into the arteries?
|
The arteries fill up with blood thus causing high arterial blood volume which raises arterial blood pressure for inflow
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|
What 3 things happen when blood flows out of the arteries?
|
The arteries are drained causing decreased arterial blood volume which lowers arterial blood pressure for outflow
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|
How is arterial blood volume and pressure determined?
|
By balance between blood flowing in and blood flowing out
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|
Define cardiac output?
|
It is the volume of blood in the heart that flows into the arteries
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What 2 factors affect blood pressure?
|
Cardiac output and arterial resistance
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What happens to the ventricles when blood flows in?
|
Ventricular contraction
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|
Blood flow out of an artery is controlled by what?
|
Resistance of Arteries
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An increase in cardiac output means what?
|
There’s an increase in inflow
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An increase in resistance means what?
|
Decreased outflow
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|
If you have increased CO and resistance what does it mean?
|
It means that arterial resistance and blood pressure will increase
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|
|
How do you calculate Mean arterial pressure?
|
MAP= Cardiac output x Total peripheral resistance (MAP=COxTPR)
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|
What 2 factors determine Cardiac output?
|
Stroke volume and heart rate
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|
How do you calculate Cardiac Output?
|
CO = Stroke volume x Heart Rate
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|
What are the units for the Cardiac output equation?
|
CO= L/min
SV=L/beat (pulse strength) HR=Beats/min (pulse speed) |
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|
Why don’t we have a pressure equation for veins?
|
Because the pressure is neglible so we can ignore it
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|
|
Define stroke volume?
|
Stroke volume is the amount of blood being ejected out of the ventricles in each beat. Both left and right ventricles have the same amount
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|
How can you change cardiac output?
|
Through exercise as it alters the heart rate and the stroke volume
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|
Where is blood pressure control of the heart co-ordinated?
|
Inside the brainstem
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|
What sort of range is arterial blood pressure regulated?
|
In a narrow range
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|
Explain the afferent input in the brainstem in terms of MAP
|
Afferent input from both the CNS and Periphery which determines the MAP
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|
Explain the Efferent output in terms of MAP
|
There is efferent output to the heart and vessels. The brain sends signals out of the system to maintain MAP
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|
What are Baroreceptors?
|
They are basically Blood pressure receptors. They are elastic and the type and amount of cells in this area tells us how much the walls are being stretched
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|
Where can you find baroreceptors?
|
In the arterial arch and the carotid artery
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|
What happens to CO in the sympathetic?
|
Increase in Cardiac output
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|
|
What happens to CO in the parasympathetic?
|
Decrease in Cardiac output
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|
|
Which node is considered as the pacemaker and what does it do?
|
The SA node is the pacemaker and is the brains way of controlling and slowing the heart rate.
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|
|
What is the opposite route to the vagus route?
|
Sympathetic chain ganglia.
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|
|
Where do the Sympathetic NS travel down?
|
Via the thoracic nerves
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|
|
Where do the Parasympathetic NS travel down?
|
Via the Vagus nerve
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|
|
Blood pressure is regulated by what 2 things?
|
Changes detected by the brainstem and control of pressure through changes to cardiac output
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|
|
Where is Cardiac output controlled?
|
In the brainstem
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|
|
What is the equation to measure flow? (Q)
|
Flow= change in Pressure divided by resistance Q=P /R
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|
|
What does the pressure of the fluid ina container depend on?
|
It depends on the volume amount
|
|
|
How is low/high pressure achieved?
|
We can lower the flow meaning the pressure will be low and get high pressure by having a high flow.
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|
|
Which blood flow do we have more control over? Low or high pressure?
|
We have more control under high pressure
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|
Is the systemic circuit parallel or series?
|
Parallel
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|
|
How is Cardiac output distributed to all organs?
|
It is distributed through continual branching of the arterial network and divides blood flow among regional circulations
|
|
|
When cardiac output is at rest what happens?
|
1) Pulmonary and systemic circuits are in series
2) The flow in is the same as flow out 3) The flow going into the system is constant throughout but when the flow splits the change but when added together they all add up to the original flow. |
|
|
How can we increase our cardiac output and where is it directed?
|
Through exercise and is directed towards our cardiac muscle
|
|
|
In exercise where does the increased blood flow go to?
|
Muscles, heart, skin
|
|
|
In exercise where does decreased blood flow go to?
|
GI tract and kidneys
|
|
|
In exercise where does constant blood flow go to?
|
The brain
|
|
|
What is the significance of the blood flow to the skin?
|
We need to dissipate the heat generated through our skin surface.
|
|
|
What happens to the blood flow to our skin under intense exercise?
|
The blood flow decreases because exercise at a level like this means we must be in an emergency state and we must increase the blood flow to the heart so we can escape the threat and the skin will be cooled down after the threat has passed
|
|
|
What type of flow do we have control over?
|
Divergent flow
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|
|
What happens to the MAP and CO when we exercise?
|
The CO increases but the MAP must be kept relatively constant and needs to be maintained at a small range
|
|
|
What happens to the resistance of the entire system as we exercise?
|
There is more flow but less resistance
|
|
|
At rest where is our blood mostly distributed?
|
To the GI tract and our muscles
|
|
|
What is the systemic circulation?
|
Heart to the rest of the body leaving via the aorta
|
|
|
What is the pulmonary circulation?
|
Heart to the lungs via the pulmonary arteries
|
|
|
How is MAP controlled during exercise in the systemic circulation?
|
Increase CO, Constant MAP and decreased TPR
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|
|
In individual circulations, what happens to the resistance when there is increased blood flow to the muscles?
|
Decreases the resistance thus more blood flow
|
|
|
In individual circulations, what happens to the resistance when there is decreased blood flow to the kidneys?
|
Increases the resistance thus less blood flow
|
|
|
What can control the resistance of individual organs ?
|
Arterioles as they are resistance vessels
|
|
|
What happens to the kidneys, intestines and spleen in exercise?
|
The resistance in the blood vessels heading to these organs increases thus decreasing the flow rate and keeping the arterial pressure constant
|
|
|
What happens to the muscles, heart and the skin in exercise?
|
The resistance decreases and the flow rate increases and keeping the pressure constant.
|
|
|
Why are arterioles the resistance vessels?
|
Because they can alter their resistance easier than most vessels. A small change in the radius causes a large change in resistance. Large radius = low resistance
|
|
|
Can arterioles alter their radius?
|
Yes, every vessel can
|
|
|
What does the resistance depend on?
|
Resistance
|
|
|
Blood flow to an organ is controlled by adjusting arteriole what?
|
Radius and tone
|
|
|
What is tone?
|
Can be either vasodilation or vasoconstriction
|
|
|
What is vasocontriction?
|
Vessels get smaller as they have a smaller radius
|
|
|
What is vasodilation?
|
Vessels get larger and have a larger radius
|
|
|
Why does the radius of the vessels change?
|
To keep the arterial blood pressure constant.
|
|
|
What are the 3 methods of controlling arterial resistance?
|
Mechanical, Neural and Humoral.
|
|
|
What is the mechnical method from within the vessel that controls resistance?
|
Blood pressure
|
|
|
What is a mechanical event from outside the vessel that controls resistance?
|
Swelling
|
|
|
How does the neural method control vascular resistance?
|
The brain sends control signals to that area which resistance need to be controlled via vascular sympathetic nerves
|
|
|
What is the humoral method of controlling vascular resistance?
|
You can control vascular resistance by releasing hormones into the blood to go to the vessels that need to change their resistance and hits the nerves that control smooth muscles
|
|
|
Which type of vessels contain most of the blood? And why?
|
Veins and venules because they store blood at lower pressures due to their compliance and thin walls and large luminal space
|
|
|
What is the difference concerning amount of blood and pressure levels between arteries and vein?
|
Veins carry large amounts of blood at low pressures whereas Arteries carry little amounts of blood in high pressure
|
|
|
Define compliance
|
Is the ability for a vessel to be deformed or change its shape due to changes in pressure or an applied force.
|
|
|
Describe the wall of veins and whether it is compliant or not
|
The walls of veins are very thin thus have a large surface area and a thin ring of muscle hence must be compliant and flexible
|
|
|
Which blood vessel has a higher compliance, veins or arteries?
|
Veins, arteries are more rigid
|
|
|
What the difference between a rigid and a compliant wall?
|
A rigid wall has a thick wall whereas a compliant wall has thin walls
|
|
|
What is a luminal space?
|
Is the space within the vessel in which blood flows
|
|
|
Are arteries compliant or rigid?
|
Rigid because they have a thick wall and has a small luminal space
|
|
|
Can veins have a large change in pressure and large change in volume?
|
Yes, unlike arteries. Small changes in pressure can cause a large change in volume thus meaning they have a large compliance.
|
|
|
What is the equation for compliance?
|
Compliance = Change in Volume /change in pressure
|
|
|
What happens to the veins if they drain out of blood?
|
Their structure will collapse as they have little muscle thus relying on the pressure of the blood to maintain its shape
|
|
|
In terms of pressure why do arteries have low compliance?
|
Because a large change in pressure causes a small change in volume as they have a rigid wall
|
|
|
Which vessel can store blood and why?
|
Veins can store blood as a reserve for usage in injuries etc
|
|
|
What happens to the pressure in veins when we increase the amount of blood going out?
|
It falls
|
|
|
In veins what is constriction called? And why does the brain control it?
|
Venoconstriction. It allows the blood draining into the heart to move to the arteries thus increasing MAP to stabilize the system
|
|
|
Why do veins have a “survival value”?
|
For arterial puncture, loss of arterial blood and for life threatening fall in arterial pressure
|
|
|
What does pooling in the veins mean?
|
Venous pooling is the accumulation of blood in the veins (of legs) due to gravitational pull when a person changes from lying down to standing up. Above the heart the venous volume decreases whereas below the heart it increases
|
|
|
What does higher vascular compliance mean for veins?
|
It means that the blood will tend to pool in the veins due to its shape
|
|
|
Why does pooling not occur in arteries?
|
Because their shape stays constant and has an even distribution of blood throughout the system
|
|
|
How can you counteract venous pooling?
|
By having venous valves or by tone of surrounding tissue
|
|
|
Are smaller veins or medium-sized veins more susceptible to pooling? And which one needs valves
|
Small sized veins with little blood has little valves whereas medium-sized veins are susceptible to pooling due to their shape so need valves
|
|
|
How do valves prevent pooling?
|
Valves only allow blood flow in one direction and if the blood tries to flow back then it will be blocked off preventing pooling
|
|
|
What type of muscle can alter its tensile state?
|
Skeletal muscle
|
|
|
What provides tone? Veins or Skeletal muscle?
|
Skeletal muscle as tone runs through it and can alter its tensile state.
|
|
|
How does skeletal muscle prevent pooling?
|
The muscle tone tends to stiffen the veins thus making is less compliant and prone to pooling or nah?
|
|
|
What do people who tend to faint have more of?
|
They tend to have low muscle tone and lots of venous pooling
|
|
|
What is the opposite of Cardiac output?
|
Venous return, which is the amount of blood returning back to the heart
|
|
|
What type of muscle affects venous return?
|
Skeletal muscle pump
|
|
|
What 2 process help venous return?
|
Contraction and relaxation
|
|
|
What happens to the blood flow when the diaphragm flexes?
|
It means more blood flow
|
|
|
Why do we breath harder when we exercise?
|
Because the muscles around the chest move faster to increase venous return
|
|
|
What is the relationship between venous return and stroke volume?
|
Increased venous return mean increased stroke volume
|
|
|
What Starlings Laws of the heart?
|
The more stretched the muscles are before a contraction means the stronger the contraction will be
|
|
|
What happens in a baro flex (whole body tilt)
|
Stroke volume falls because we don’t have blood returning to the heart thus less venous return
|
