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228 Cards in this Set
- Front
- Back
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what causes driving force for unidirectional movvement of blood throughout body
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pumpin of heart
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site of exchange
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cap. almost all cells in body are within a few cell diameters of the cap
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two major components of circulartory system
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pulmaonary and systermic
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CO of brain
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650 ml/min about 13% of total
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CO of heart
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215 ml/min 4% of total
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CO of skeletal muscle
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1030 mL/min about 20% of total
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Skin CO 430 mL/min
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9 % of total
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Kidney CO
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950 ml/min or 20% of total CO
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Abdominal CO
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1200 ml/min or 24% total CO
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total CO per min
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5000 mL/min
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What happens to O2 and CO2 at perephereal system?
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O2 leaves the blood and enters the interstitial space and CO2 leaves the interstial space to enter the blood
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What happends to O2 and CO2 in pulmonary system?
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Blood flowing through lungs picks up O2 from alveoli and CO2 leaves blood and enters alveoli
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Describe blood flowing through GI
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pu nutritens and delivers them to the interstial space. Metabolic waste entersthe blood from the interstial sapce and is delived to organs for elimination
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How does blood flow?
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from hight hydrostatic pressure to lower hydrostatic priessure
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pressure gradient
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difference between hi hydrostatic pressure and lo hydrstatic pressure
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What happens if increase pressure gradient
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increase the blood flow
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2 things blood flow must overcome
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viscosity and resistance
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What causes resistance to blood flow?
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shear forces that exist between the blood and the vessel wall and viscosisity of blood
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Resistance equation
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R=(nL/r4) (8/pie)
n is viscosity is L is blood vessel length, r is radius of blood vessel |
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Must important factor of blood flow resistance
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the radius of blood vessel because it is raised to the fourth in the equation. A little change in the blood vessel radius casue a large change in the blood flow
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what happens with blood O2 at lungs?
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picks up O2 from alveoli and CO2 leaves the blood and enters the alveoli
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What happens with blood O2 at the periphery?
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OXYGEN LEAVES THE BLOOD AND ENTERSTHE INTERSTITIAL SPAACE AND CARBON DIOXIDE LEAVES THE INTERSTIATIAL SPACE AND ENTERS THE BLOOD
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Describe blood through the GI system
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PU nutriets in GI and delivers them to the interstitial space.Metabolic waste products enter the blood from the interstidal space and are delivered by the blood to many organs for elimination from body
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Where are nutrients picked up by the blood stream?
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in the GI, mainly the SI, delivers nutrients to periphereal tissue
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How does blood flow?
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from a region of higher hydrostatic pressure to a region of lower hydrostatic pressure. the difference between the higher and lower pressure is the pressure gradient
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increase BP does what to blood flow
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increases blood flow
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what does ventricles do to hydrostatic pressure?
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hyrostatic pressure of blood is increased by ventricle action
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driving force of blood flow to perephei and lungs
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pressure increase casued by ventricle contraction
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how is blood flow measured?
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units of vol/time
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Does blood viscosity change under normal conditions?
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no the length of the blood vessel doesnt either
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Basic equation that related blood flow to pressure and resistance
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F= P/R
Flow is directly porportional to pressure gradient and inversely proportional to the vascular resistance |
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four chambers of heart
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left atrium, left ventricle, right atrium, and right ventricle
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what composes wall of heart?
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cardiac muscle cells called myocardium
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inner surface of the cardiac chambers
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endothelial cells
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mitral valve
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between the left atrium and the left ventricle. allows blood to flow from the atrium into the ventricle. The valve opens passively when blood pressure in left atrium is higher than the BP in the left ventricle. if blood tries to move back from the left ventricle into the left atrium the valve closses
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what prevents the mitral and tricuspid valve from being pushed back and causing blood to go back into the left atrium
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papillary muscles
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ouflow valves
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pulmonic valve on R and aortic valve on L
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tricuspid valve
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located between right atrium and right ventricle and only allow blood to go from atrium to ventricle. Valve open when more pressure in right atrium than ventricle.
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aortic valve
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between left ventricl and aorta. only open when blood pressure is higher in L ventricle than aorta opens passively and allows blood out of aorta. valve closes if pressure increases in aorta
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Pulmonic valve
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located between right ventricle and pulmonary trunk and nly allows blood to go from venticles into pulmonary trunk. Valve opens when BP in right ventricle is higher than the BP in pulmonary trunk. If blood tries to move back from the pulmonary trunk int the R vnetricle, the valve closes passively
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AV valves
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mitral and tricuspid valve
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Describe cardiac muscle
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striated like skeletal m but indiviual cells are shorter than skeletal m.
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What joins cardiac muscle cels end to end
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intercalated disks
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what is adjacent to intercalated disks in cardiac muscles?
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gapjunctions permits cell to cell conduction of action potentias
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what innervates heart?
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PS and Symp
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primary sympathetic NT and receptor
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Norepi and Beta receptors
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primary PS NT and receptro
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ACH to M receptor
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BF to Cardiac muscle
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Coronary A.
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BF away from heart
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coronay sinus which enters in right atrium
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two things that must occur for effective heart pumping
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Both sides of the heart must be activated to beat in some sort of regular fashion and on each side of heart, the atrial pump must be activated befor ventricular pump is activated
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SA node
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cardiac cell with pacemaker activity that spontaneously depolarizes/repolarizes. locarted in R atrium near SVC. it produces Cardiac AP causing contracton
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What sets heart rate?
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SA node, pacemaker of heart
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what initiates heart beat?
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SA node
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Conduction of contracton
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SA node depolarizes and causes both atria to depolarized and contract simultanelously. AV node depolarizes at base of R atrium and cases ventricles to depolarize. Budle of His splits to pukinje fibers at apex cause rapid contraction
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only electrical connection between atriia and ventricles
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AV node
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Conduction of AP through AV node
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V. slow allowing the atrial contractions to be completed before ventricular depolarization occurs
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bundle of His
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divides into L and R. at apex purkinje fibers get AP and rapid contracton occurs
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fasted part of conduction
Slowest |
slowest at AV node, fastest at Bundle of His
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resting membrane potential of cardiac muscle cells
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- 90 mV
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What does action potential consist of?
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A period of rapid depolarization and a period of rapid repolarization.
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distinctive feature of cardiac aaction potential
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plateu phase exists between depolarization and repolarization causing a long action potential
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five named phases of cardiac action potential
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phase4 resting memebrane potential
phase0 rapid depolarization phase1 initial repolarization phase2 plateau phase3 final repolarization |
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what does rapid depolarizaton of cardiac muscle cell cause?
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opening of voltage gated sodium channel when increase sodium permeabiity and siultaneous decrease in potassium permeabiity.
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What is plateur phase?
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result of potassium channels remaining closed to inhibit repolarization and the voltage gated calcium L type channels open at the end of depolarization allowing calcium ions to enter the cell
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What allows final repolarization of the cell?
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Calcium channels closing and Potassium channels opening
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Excitatin of SA node
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no stable resting membrane potential but exhibit a slow depolarization during the resting stage causing cell to slowly reach threshold causing AP. NO plateu phase in SA
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deos SA require nerves
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NO! it is intrinsic of heart
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what is slow depolarization a result of?
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two ionic permeablilty changes
Volgage Na channels open as a result of previous repolarizion and T type Ca chanel open to cause positive charge in the cell. |
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What happens once SA cell reaches threshold due to slow depolarization?
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voltage gated Ca channnel L type opens to bring more Ca in.
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intrinsic rate of fining of SA node
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100/minute
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Why is heart rate 70beats/min even though intrinsicrate of firing of Sa node is 100\min?
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bc PS activiy supply SA node predominates over symp activity
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What happens without SA node?
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other regions of heart still have pace maker actiivgy but slower than SA node bc it is the fastet. IF SA node gone use AV node
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P wave
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Atrial depolarizaton
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QRS complex
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ventricular depolarization
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T wave
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venticle repolarizaition
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Flat pt between P and Q on EKG
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due to delay at AV node becuase it is slow to depolarize
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Why cant we see atria repolariztion on EKG?
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Bc very small and occurs ame time as ventricular depolarization which is freaking huge
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EKG
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provides a means of recording the electrical activity of the heart from externally applied electrodes
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What does EKG look for?
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electrical abnormalities NOT mechanical
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PR interval
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measure of time from P to Q it is the prolongation of conduction of AP through the AV node
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QT interval
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amount of time ventricle is contracting. Q starts contracton and T is relaxing
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ultimate stimulus for cardiac muscle contraction is
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increase in cytosolic Ca concentration
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How is cardiac contraction carried out?
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depolarization of membrane
causes opening of plasma membrane Ca channels in T tuble. Ca flows into cytosol. Ca binds to Ca recepotor to SR. causing opeing of intrinic Ca channels so more Ca flows into cytosol further increaseing Ca cytosolic conc. causing contraction |
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How is cardiac muscle repolarized
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removal of Ca from cytosol and put back into SR by Ca ATPase and removed from cell to exterior by Ca ATPase and Ca/Na exchanger
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What is amount of fee Ca avaible to trigger cross bridge formation a direct deterinant of ?
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strength of cardiac contraction.
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refractory period of cardiac m.
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no further muscle contractions can be elicited last as long as contraaction itself. Caused by long plateu phase
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Is it possibe to produce tetanic contractions in cardiac muscle?
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no bc long refractory period due to long plateu phase
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two phases of cardiac cycle
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diastole and systole
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diastole
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cardiac ventricles are relaxing and filling with blood from atria
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systole
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cardiac ventricles contract and eject blood into the aorta and pulmonary arteries
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rapid filling phase
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early in diastlole when pressure gradient is relatively large
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slow filling phase
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diastole prgresses and pressure gradient decreases causing ventricle filling to be slower
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atrial contraction phase
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as result of elecrrical activity the left atrium contracts and pushes a little more blood into the ventricle
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total volume of blood at end of diastle
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EDV
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steps of diastole
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rapid filling
slow filling atrial contraction |
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how much blood is ejected from hert during normal contraction
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only 50-60%
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describe ventricular contraction
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mitral valve closes stopping the flow of blood back into the atrium and at this time the aortic valve is still close bc pressure in the aorta os way higher. as the contraction continues, the ventricle pressure increases to exceed aortic pressure to aortic valve opens and blood goes thrhough rapidly
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isovolumic contraction phase
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so ventricle initially contracing and both mitral and aortic valve are closed at this point both the valves and the walls of the closed chamber are contracting
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Mitral valve problem
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causes atrial hypertrophy
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period of time between closing aortic falve and opening mitral valve
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isovolumic relaxingation period
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what causes slow filling phase of ventricle
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atrial pressure wquals ventricular pressure
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end systolic volume
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amount of blood in ventrilce at the end of the ejuecttion phase
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Stroke vol
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EDV-ESV
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Ejection fraction
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amount of blood ejected during a contraction
Strokvol/End Diastolic vol |
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Ejection fracton in normal individulas
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60%
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During diastlole what happens to aortic pressure?
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it decreases from a peak value of 120 mmHg to a pressure of 80 mmHg. Decrease in pressure is due to blood leaving aorta and going to periphery
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major diffenence in right and left side of heart
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peak prssure in R is 24 mmHg and diastolic is 8 mmHg while left pressure is 120 mmHg/70 mmHg
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What causes Pressure difference between R and L sides of heart?
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vascular reisstanc in systemic is much higher than pulmonary
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what produce heart soundsS?
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passive closing of cardiac valves
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First heart sound
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lub is result of closing of the mitral and tricupsid valve at the end of diastole
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Second heart soundd
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dub is result of closing the aortic and pulmonic valves at the end of systole
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Heart murmur
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caused by blood flowing through abnormally small opening or in narrowed blood vessel. Valves dont open or close properly
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What is splitting of second heart sound caused by/
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respiratory cyle? Take break decrease intra thoracic pressure so lungs expand, descending the diaphragm increases vol in thoracic cavity and decreases pressure so increasing pressure gradiend for blood to flow through IVC adding more blood on the right.
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When inhale what side of heart gets more blood?
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Right. causing delay of pulmonic valves
When exhale get more load on Left |
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The volume of blood pumped by each ventricle per minute
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cardiac output
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what is cardiac out put for an average adult
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5 L/min
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Stroke volume
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amount of blood ejected by each ventricle with each beat
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Cardiac output equation
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CO = Stroke volume X Heart
Rate |
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Diffence in CO between R and L heart
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no difference they are in series so the CO is equal on both sides
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Parasympathetics effect on SA node
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decrease rate of fining and decrease in heart rate
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sympathectic effect of firing on SA node
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increase the rate of firing and increases heart rate
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If heart rate increases what happens to stroke volume?
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it decreases.
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How does increasing sympathetics on SA increase the heart rate?
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Increasing sympathetics increases the number of Na and Ca T channels that open which causes the membrane potential to reach threshold faster causing more SA node AP and increasing the HR.
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How does incrasing parasympathetic on SA decrease the heart rate?
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decreases the number of Na and Ca T type channels that normally open in the membrane so it takes longer to reach threshold. Fewer SA AP occur so heart rate decreases
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What is responsible for changes in the slope of diastolic depolarization?
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the opening or closing of the special Na and Ca T type channels in the SA membrane
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Epinephrine effect on the heart
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releases from the adrenal medually and it increases the heart rate by interacting with the same beta rector as noperp
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Other factors beside parasymp and symp and effect the heart rate
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body temp, serum electorlyte conc. and adenosine
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Adensine
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increseases heart rate. Released during excercise
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What happens if you increse the left ventricular end diastolic vol?
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Increase stroke volume of pump because you increase he volume and therefore increase the fiber length
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What happens to stroke volume as ventrucular diastolic volume increases?
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stroke volume increases. because as heart fills the muscles stretch, increasing fiber length and causing a more forceful contraction
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Frank starling mechanism
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Stroke vol vs Ventricular end diastoic vol. basically as end diastolic volume increases, stroke volume increases too. this is an intrinsic property of cardiac muscle
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Consequence of Frank starling mechansim
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CO of both ventricles are equal
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wHAT DOES SYMP ACTIVITY DO TO CARDIAC CONTRACTILITY?
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IT INCRESES IT.REMEMBER THAT CONTRACTILY IS INDEPENDENT OF CHANGES IN EDV
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What does sympathetic activity do to frank starling graph curve
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shifts it up and left bc increase in symp causes an increase in stroke volume due to increase cardiac conductivity
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three mechanisms that are responsible for increases in cardiac contractility
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1. opening more plasma membrane Ca L type channels during plateu phse
2. stimulating Ca reabsorbion into SR 3. altering the binding of Ca to troponin |
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what is an increase in cardiac contractily a result of?
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increase in the amount of free calcium in the cytool during contraction and the rate of removal of Ca from the cytosol durnig relaxation
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PS effect on cardiac contractility
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ventricles receive little PS so no effect on cardiac contractility
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Afterload
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magnitude of the aortic pressure or pulmonary artery pressure against which the ventricle must eject its blood
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What does and increase in afterload do to Stroke volume
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causes stroke volume to decrease bc it is applying the same force but there isgreater resistance
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What happens if you block L type Ca channels
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decrease both conductivity and stroke vol
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wHAT DOES INCREASE IN SYMP NERVE TO HEART DO?
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IT INCREASES STROKE VOLUME OF CARDIAC MUSCLE AND INCREASES SA NODE TO INCREAE HEART RATE. OVERALL CAUSES AN INCREASE IN CARDIAC OUTPUT
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WHAT DOES AN INCREASED EDV DO?
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IT INCREASE SV OF CARDIAC MUSCLE CAUSES AN INCREASE IN CO
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WHAT LINES PERIPHERAL VASCULAR SYSTEM?
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ENDOTHELIAL CELLS.
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WHAT ARE CAPS COMPOSED OF?
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ENDOTHELIAL CELLS ONLY
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BF RESISTANCE OF ARTERIES
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LOW RESISTANCE BC VESSELS HAVE A LARGE DIAMETER
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when does systole start?
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when aortic valve opens, diastole is when aortic valve closes
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dicrotic notch
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point in time when aortic valve closes
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systolic pressure
- diastolic pressure |
pulse pressure, basically the change in the pulse in a single ejection
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what happens to BP with age?
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as you age BP increases due to changes in compliance. vessels get stiffer.
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Mean arterial pressure
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diastloic pressure + 1/3PP
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what is magnitude of pulse pressure determined by?
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amount of blood ejected by ventricle per beat (stroke vol)
rate of ejection of blood from ventricle compliance of the arterial system |
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what happens if ventricle ejects blood too rapidly?
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arteries cant adapt so it takes longer to fill
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compliance
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indicates how easlity an elastic structure can be stretched
compliance=vol/pressure |
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describe central aorta ejecting blood
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blood ejected from ventricle is greateer that amount of blood that goes into peripheral. aortic wall stretches and excess blood ejected into aorta is stored making it large and storing energy. during diastole when ventricle is not ejecting blood, the aorta contracts and the stored elastic enery provides additional driving pressure to help the movements of blood in the peripheral circulation
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BV with most pressure
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arteries
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BV with least pressure
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veins
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importance of arerioles
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detemine the relative blood flow to various organs and play a major role in the MAP
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major site of resistance in periphereal vascular system
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arterioles
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Ohms law
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Flow=pressure/resistance
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BF RESISTANCE OF ARTERIES
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LOW RESISTANCE BC VESSELS HAVE A LARGE DIAMETER
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when does systole start?
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when aortic valve opens, diastole is when aortic valve closes
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dicrotic notch
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point in time when aortic valve closes
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systolic pressure
- diastolic pressure |
pulse pressure, basically the change in the pulse in a single ejection
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what happens to BP with age?
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as you age BP increases due to changes in compliance. vessels get stiffer.
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Mean arterial pressure
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diastloic pressure + 1/3PP
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what is magnitude of pulse pressure determined by?
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amount of blood ejected by ventricle per beat (stroke vol)
rate of ejection of blood from ventricle compliance of the arterial system |
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what happens if ventricle ejects blood too rapidly?
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arteries cant adapt so it takes longer to fill
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compliance
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indicates how easlity an elastic structure can be stretched
compliance=vol/pressure |
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describe central aorta ejecting blood
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blood ejected from ventricle is greateer that amount of blood that goes into peripheral. aortic wall stretches and excess blood ejected into aorta is stored making it large and storing energy. during diastole when ventricle is not ejecting blood, the aorta contracts and the stored elastic enery provides additional driving pressure to help the movements of blood in the peripheral circulation
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BV with most pressure
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arteries
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BV with least pressure
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veins
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importance of arerioles
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detemine the relative blood flow to various organs and play a major role in the MAP
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major site of resistance in periphereal vascular system
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arterioles
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Ohms law
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Flow=pressure/resistance
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what determines vascular resistance?
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arterioles radius (because to the fourth power)
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What surrounds arterioles?
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smmoth muscle with intrinsic tone. the muscle is controlled by sympathetic nerve activity
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potent vasodialators
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potassium and adenosine. cause increase Blood flow
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Active hyperemiea
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increased blood flow as a result of increased metabolic activity. reslt of production of loss of certain materials in immmediate vicinity wi the vascular bed. Ex. increased Oxygen of CO2, adenosine or potassium causes an increae in BF
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flow autoregulation
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maintain blood flow in face of changesin MAP. occurs by increasing BP, cause BF to increase but organ doest need it so constrict the arteriole to the organ
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what happens if you increase metabolic activity of the tissue
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automatically increase BF to that tissue
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NT to arterioles
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sympathetics norepi NT and alpha receptors. only symp present in arterioles. If NT release and binds to recepotor cause constriction of arterioles and decreases BF
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Why does changing sym not effective to controlling BF to specific organ?
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bc the effects of symp discharge occur throughout the body
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Most common way to control BF to specific organ
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reguating the arterial blood pressure
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What neurons release NO?
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noncholinergic and nonadrenergic
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NO
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vasodialatore. they control BF in GI and penis.
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Function of epinephrine in arterioles
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if it binds to alpha receptors causes vasoconstriction. If it binds to beta receptors on arterioles in skeletal m. it causes vasodilation
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angiotensin II, vasopressin
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vasoconstrictiors
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ANP
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vasodilator released by atria of heart
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what happens when endothelial cell secrete paracrine agents?
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diffuse to nearby vascluar smooth muscle cells and induce either vasoconstricion or vasodialation
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PGI2 prostacyclin
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not continuously relesed like NO but it is a vasodialator
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Endothelin
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paracrine vasoconstrictor
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precapillary sphincter
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vascular smmoth m. around smaller vessels. Controls BF to down stream capillaries
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major site of exchange of nutrients and metabolic end products
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Capillaries
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Typical cap structur
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thin walled tube of endothelial cells one layer thick resting on a basement membrane without smooth m.
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What is between endotheial cells in cap
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intercelluar fluid
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what is cap blood flow dependent on?
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state of contraction or relaxation of upstream arterioles
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What causes constriction or dialation of metarterioles in cap bed?
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local metabolites
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Blood flow velocity equation
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V = F/A
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sequence movement of nutrient
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Blood plasma through cap wall into Interstial fluid and then into cell.
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Purpose of bulk flow
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distributing ECF
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what governs the fluid across the cap wall
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starlings law of capillary
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net filtraion pressure equation
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(Pc - Pif) - (IIp-IIif)
Pc=cap hydrostatic P Pif=interstitial p IIp=osmotic P due to PP IIif-intertial P due to PP |
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What does negative net filtration pressure mean?
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it is absorbed. goes back into cap
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in systemic cap beds, when is there a net movement of fluid out of capalaries?
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At arterial end and a net movement of fluid into the capalaries at the venous end
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What happens if increase symp to veins?
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displace blood to artioles to increase pressure in arterioles bc fluid moves from veins to arterioles
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Do veins exchange material?
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NOOOOOO!
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Driving force for blood flow form veins back to the heart
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pressure gradient between the peripheral veins and the R atrium
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Function of veins
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return blood to heart and to as storage function bc total volume of the peripheral veins can be altered by sympathetic nerve activity on vascular smooth muscle in the walls of the vessels cause vasoconstriction and pushing blood into arterioles
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reservoir for blood in systemic circulation
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Veins
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What two things happen in inspiration?
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diaphragm descends down increasing th intraabdominal pressure and peripheral venous pressure. the intrathoracic pressure decreases and decreases the veins in the thorax. The increase in ab venous pressure and decrease in thoracic venous pressure increase pressure gradient and increases amount of blood flow to the heart this is the respiratory pump
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% of Blood vol in veins
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60%
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amount of lymph reabsorbed each day
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4 L
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Why doesnt peripheral interstial space accumulate fluid or proteins?
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bc th lymph picks it up and returns it to circulatory system
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Venous pooling
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standing and not moving therefore not using skeletal muscle so blood goes away from arterilole side to veins so BP decreases and there is not enought oxygen to brain so you pass out
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smooth muscle of lymph
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exhibits rhythmical contractions and propels the lymph to the heart. Vessles also have valves to allow unidirectional flow
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What activates smooth muscle around lymph vessels
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stretch. it begins contracting when the vessels are distended. Also sympathetic innervation activates the smooth m. around the vessels along with the respiratory pump
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What happens if lymph is blocked?
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fluid accumulation in periphereal system, edema
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How is absorbed fat carried to cardiovascular system?
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lymph
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baroreceptor action if artial pressure increases
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arterial baroreceptors increase fireing reflex via medulary cariovascular center causing decrease sympathetic to heart, arteries causing decrease SV, CO, and vasodialation causes artiole blood to go to venous side. It also causes parasympathetics to the heart to increase so SA and AV node decrease to decresase HR
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major cardiovascular regulator
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MAP in systemic circulation
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MAP equation
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MAP = CO X TPR
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What controls MAP over seconds to hours?
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baroreceptor reflex and hormonal secretions
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special collecion of nerve ending bilaterally in carotid sinus and in aortic arch
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baroreceptors
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Describe baroreceptors
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stretch receptors whose rate of firing depends on pressure in aorta carotid sinus. Sends output to heart, arterioles, and veins
If BP increases, stretch increases, baroreceptor firing increases causing decrease symp and increase PS |
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How is BP regulated long term?
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blood volume of kidneys
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Cardiac Catherization
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measure pressure of heart. Can see ventricles and locate plaques or clots
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ETT
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excericise with EKG see where pt feels pain
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Echocardiogram
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non invasiove. see 2D of heart.
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