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82 Cards in this Set
- Front
- Back
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What type of circulatory system do mammals have? |
A closed, double circulatory system. |
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What does a closed system mean? |
Blood is confined to vessels (arteries, arterioles, veins and capillaries) |
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What does a double system mean? |
Blood passes twice through the heart for each complete circuit of the body. |
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What does blood do? |
It transports respiratory gases, products of digestion, metabolic waste products and hormones around the body. |
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What does the pulmonary artery do? |
Carries blood from the heart to the lungs |
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What does the pulmonary vein do? |
Carries blood from the lungs to the heart |
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What does the aorta do? |
Carries blood from the heart to the body |
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What does the vena cava do? |
Carries blood from the body to the heart |
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What does the renal artery do? |
Carries blood from the body to the kidneys |
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What does the renal vein do? |
Carries blood from the kidneys to the vena cava. |
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What does the right side of the heart do? |
It pumps deoxygenated blood to the lungs |
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What is the pathway of blood through the right side of the heart? |
Vena cava--> right atrium-->right atrioventricular valve-->right ventricle-->semi-lunar valve-->pulmonary artery-->lungs |
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What does the left side of the heart do? |
It pumps oxygenated blood around the body. |
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What is the pathway of blood through the left side of the heart? |
Lungs-->pulmonary vein-->left atrium-->left atrioventricular valve-->left ventricle-->semi-lunar valve-->aorta-->body |
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How many chambers does the heart have and what are they? |
4 2 atria 2 ventricles |
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What is a difference between the atria and the ventricles? |
Ventricles have thicker walls than the atria so they can push blood out of the heart. |
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Why do atria have thinner walls? |
They only need to push blood from the atria into the ventricles, the distance is smaller. |
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Which ventricle has a thicker wall and why? |
The left ventricle as it has to pump blood all around the body, whereas the right only has to pump blood to the lungs |
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What does the septum do? |
It separates the 2 sides of the heart, so oxygenated and de-oxygenated blood don't mix.
It also enables there to be different pressures on each side of the heart. |
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What is the difference between the superior and inferior vena cava? |
The superior is at the top of the heart, the inferior is at the bottom |
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What are the 2 types of valves in the heart? |
Atrioventricular valves Semi-lunar valves |
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What can be seen on a diagram of the outside of the heart? |
The left and right coronary arteries |
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What do the left and right coronary arteries do? |
They supply the heart with blood and oxygen because it doesn't use the oxygen that passes through the left side of the heart. |
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What do arteries do? |
They carry blood from the heart to the body. |
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What do they form? |
They divide into smaller blood vessels called arterioles to form a network throughout the body. |
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What is the lumen like in the artery? |
It's small to maintain the blood pressure |
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What is the wall of the arteries made of? |
Endothelium, collagen fibres, fibrous proteins, elastic fibres, smooth muscle |
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What is the function of the collagen fibres and fibrous proteins? |
They mean that the thick wall can withstand high pressure. |
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What is the function of the elastic tissue? |
It allows the wall to stretch and recoil to maintain diastolic blood pressure |
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What are two features of the endothelium and what do they do? |
It's smooth to reduce friction and folded so it can unfold when the artery stretches. |
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What does the smooth muscle do? |
It allows contraction and vasoconstriction which narrows the lumen |
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What does the smooth muscle do in arterioles? |
It enables blood to be directed to different areas of demand in the body. Muscle contracts to restrict blood flow and relaxes to allow full blood flow. |
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What is the pressure like in arteries? |
Blood is at very high pressures due to the contraction of the left ventricle muscle. |
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What do veins do? |
They carry blood back to the heart |
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What is the lumen of the veins like? |
It's large to ease the flow of blood |
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What are the walls of veins made of? |
Endothelium, collagen, elastic fibres, smooth muscle but there is less of this than there is in arteries. |
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What is the wall like? |
Thin but strong |
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What else do veins contain? |
Valves which prevent the back flow of blood |
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How is blood moved through the veins? |
Heart pressure is exerted by the movement of the muscles and there's some residual pressure from the contraction of the left ventricle muscle wall |
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What is the pressure like in the veins? |
The blood is at a low pressure |
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What do arterioles branch into? |
Capillaries |
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What is the role of the capillaries? |
Molecules are exchanged between the capillaries and cells. |
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What forms the wall of the capillaries and effect does this have? |
A single layer of endothelial cells. They're only 1 cell thick which reduces diffusion distance |
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What is the lumen like in the capillaries and what does this mean? |
It's narrow and the same diameter as red blood cells. This means erythrocytes are squeezed through and reduces diffusion distance. |
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What is a feature of the endothelium? |
It's smooth to reduce friction for blood flow |
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What is another feature of the endothelium? |
There are gaps between endothelial cells to allow nutrients to pass through. |
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What can't pass through these gaps? |
Proteins |
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What is a feature of capillaries? |
They have a large surface area which increases rate of diffusion. |
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What is pressure like in the capillaries? |
It's high at the arteriole end due to the contraction of the left ventricle wall but pressure falls as it goes towards the venous end. |
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Which blood vessel has the thickest walls in descending order? |
Arteries Veins Capillaries |
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Which blood vessel has the highest blood pressure in descending order? |
Arteries Capillaries Veins |
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Why does pressure decrease in the different blood vessels? |
As you go further from the heart, the vessels branch and the cross sectional area increases. |
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Why does pressure in the veins fluctuate? |
This is due to the left ventricle muscle wall contracting and relaxing. Contractions raise pressure. |
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What else can be found in the heart? |
Tendinous chords |
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Why does systole mean? |
Contraction of cardiac muscle |
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What does diastole? |
Relaxation of cardiac muscle |
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How long does the average cardiac cycle last? |
0.8 seconds |
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What is the average heart rate? |
75 beats per minute |
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How many stages of the cardiac cycle are there? |
3 |
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What happens in stage 1? |
The atria fill with blood and contract (atrial systole). This decreases the volume and increases pressure. This opens the atrioventricular valve allowing blood to enter the ventricle. |
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What happens in stage 2? |
The ventricles contract (ventricle systole) which decreases volume and increases pressure. Atrioventricular valves shut and semi-lunar valves open. |
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What happens in stage 3? |
The ventricles and atria relax (diastole) and the semi-lunar valve closes. Atria fill with blood and the cycle starts again. |
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When do valves open? |
When the pressure below the valve is greater than the pressure below it. |
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When do the atrioventricular valves open? |
When the pressure in the atria is greater than the pressure in the ventricles. |
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When do the semi-lunar valves open? |
When the pressure in the ventricles is greater than in the arteries. |
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When do valves close? |
When the pressure above them is greater than the pressure below. |
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Why do valves close? |
To prevent the backflow of blood. |
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What do tendinous chords do? |
They prevent the valve inverting |
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What happens to aortic pressure in the 3 stages? |
Atrial systole- constant Ventricular systole-increases Diastole-decreases |
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What happens to ventricle pressure in the 3 stages? |
Atrial systole- increases
Ventricular systole-rapidly increases Diastole- rapidly decreases |
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What happens to atrial pressure in the 3 stages? |
Atrial systole- increases
Ventricular systole-decrease, then increases Diastole- decreases then increases |
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What happens to ventricle volume in the 3 stages? |
Atrial systole- increases slightly
Ventricular systole- decreases Diastole-increases |
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What does an ECG show ? |
In atrial systole, the trace decreases, it then begins to rise and peaks in ventricular systole (highest peak). It decreases again and slowly rises. It remains steady during diastole. |
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What does an ECG do? |
It monitors the electrical activity of the heart and turns it into a trace. |
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What generates electrical activity? |
The heart. It spreads through nearby tissue and sensors on the skin pick up the electrical excitation created by the heart. |
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What is the equation for cardiac output? |
Cardiac output=heart rate x stroke volume |
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What is cardiac output measured in? |
cm3 min-1 |
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What's stroke volume measured in? |
cm3 |
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What's heart rate measured in? |
min-1 |
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What is cardiac output? |
The volume of blood pumped by the heart per minute |
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What is stroke volume? |
The volume of blood pumped during each heart beat |
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What is heart rate? |
The number of beats per minute |
