Physiology of Cardiovascular System Flashcards
What is the purpose of the cardiovascular system?
deliver oxygen and nutrients to organs, tissues, and cells and transport carbon dioxide for elimination
How big is the heart?
the size of a man’s closed fist
What is the function of the heart?
to pump enough blood to meet the body’s metabolic needs
Where is the heart located?
Thoracic cavity in the mediastinum, above the diaphragm, behind the sternum, in front of the spine
What is the top of the heart called?
base
What is the bottom of the heart called?
Apex
What are the 4 layers of the heart?
pericardium, epicardium, myocardium, endocardium
Which layer is a double-walled sac that encloses the heart and serves as support and protection?
pericardium
________ is found between the layers of the pericardium to minimize friction of the layers as they rub together with each heartbeat.
Pericardial fluid
Which layer is the outermost layer that contains coronary arteries?
Epicardium
Which layer is the middle and thickest layers that is made of muscle?
Myocardium
Which layer is the thin innermost layer that forms the heart valves?
Endocardium
What is the job of the heart?
to pump
Which layer deals with the heart pump?
myocardium
What is the job of the aorta, arteries, and arterioles?
distribution system
What kind of walls are the aorta, arteries, and arterioles?
elastic and muscular (smooth)
What is the job of the capillaries?
exchange vessels
Skeleteal muscles have a ____ capillary network.
dense; 2,000-3,000 per square mm, 1 in 30-40 open at rest
What is the job of the veins?
Collection and return system
How much of the body’s blood volume do the veins hold?
64%
What are the 4 things associated with the heart as a pump?
electrical activity, mechanical activity, cardiac output, and coronary blood flow
______ is the rate and rhythm of cardiac muscle contraction PLUS.
Electrical activity
______ is the contraction and coordination of cardiac muscle and heart valves EQUALS.
Mechanical activity
______ pumps blood and oxygen through pulmonary and peripheral circulations REQUIRES.
Cardiac Output
_____ delivers blood and oxygen to heart muscle.
Coronary blood flow
What are the 2 main heart valves?
Semilunar valves and AV valves
What are the 2 semilunar valves?
pulmonic and aortic valve
Which valve is between the right ventricle and pulmonary artery?
pulmonic valve
Which valve is between the left ventricle and aorta?
Aortic valve
What are the 2 AV valves?
Tricuspid and Mitral valve
Which valve is between the right atrium and right ventricle?
Tricuspid
Which valve is between the left atrium and left ventricle?
Mitral
What type of muscle is striated and has intercalated disks?
Cardiac
What 2 filaments does the cardiac muscle have?
Actin and Myosin
_____ is a specialized cell membrane that separates cardiac muscle cells from one another.
Intercalated disks
What do the intercalated disks allow?
AP to easily pass from one cell to the next
Cardiac muscle is a _____ of many cardiac muscle cells.
syncytium
What happens when one cardiac muscle cell depolarizes?
all cells depolarize (allows for contraction)
Cardiac muscle is tuned for ____ metabolism.
Aerobic
What are the 4 characteristics of cardiac cells?
Automaticity, excitability, conductivity, and contractility
_____ is the ability to create an impulse without outside stimulation.
Automaticity
_____ is the ability to conduct an impulse to neighboring cells
Conductivity
_____ is the ability to depolarize.
Excitability
_____ is the ability to contract.
contractility
All but ____ are electrical characteristics.
Contractility
What characteristic is contractility?
mechanical
____ is the ability to spontaneously generate an AP.
automaticity
What are 2 examples of automaticity?
SA node, AV node
_____ rapidly transmit AP through heart.
Conductive properties
What are two examples of conductive properties?
Av bundle, Purkinje fibers
Pacemaker cells are ______.
automaticity
Specialized muscle cells are _____.
myogenic (self-excitable)
What does the ANS do to myocardial cells?
sends signals to speed up or slow down HR
What is the natural rate of discharge of SA node?
100 bpm
What is the normal heart rate?
70 bpm
The AV node discharges how many bpm?
40-60
Bundle branches and Purkinje fibers discharge how many bpm?
20-40
What is the primary pacemaker?
SA node
What is the secondary pacemaker?
AV node
What is the tertiary pacemaker?
Bundle branches and Purkinje fibers
What is the SA node resting membrane potential?
-55 to -60 mV
Automatic slow leakage of Na+ into SA nodal cells leads to spontaneous _______.
Depolarization
When other cardiac tissue generates a faster depolarization rate, it is known as _____.
Ectopic pacemakers
What is the resting membrane potential of cardiac muscle (non pacemaker cells)?
-85 to -95 mV
AP of cardiac muscle is caused by opening of fast ____ channels.
sodium
How long does the plateau last in a ventricular cardiac muscle?
.2-.3 seconds (15x longer than skeletal muscle)
What caused the plateau?
slow calcium channels
How long did the refractory period last in ventricles of cardiac muscle?
.25-.30 seconds
What caused the refractory period?
opening of potassium channels
In cardiac muscles, AP causes release of ____ from the sarcoplasmic reticulum.
Calcium
Calcium can flow through t-tubles _____ from extracellular fluid.
directly
Calcium release in cardiac cells leads to interaction of ____ and _____.
actin, myosin (excitation-contraction coupling)
What is the order for conduction through the heart?
Sa node, atrium, AV node, Purkinje fibers, ventricle
Why is there a delay of impulse at AV bundle?
the concentration of intercalated disk is much less
P wave = SA node _______.
Depolarization
Spread of depolarization across atria causes contraction of ____.
atria
What are the 4 phases of systole?
isovolumetric contraction, ventricular ejection, protodiastole, isovolumetric relaxation
______: ventricles contract but no blood is flowing.
Isovolumetric contraction
________: pulmonary and aortic valves open during ventricular contraction, at pressures of 8 mmHg (pulmonary) and 80 mmHg (aortic).
ventricular ejection
Left ventricular contraction generates a pressure of 120 mmHg in _____ and lasts .08-.12 seconds.
aorta
______: blood flow slows as pressures equalize.
protodiastole
_____: ventricles relax, valves close.
isovolumetric relaxation
____ valves are closed during systole.
AV
What happens to the ventricles during diastole?
they relax and fill with blood
What valves close during diastole?
Pulmonary and aortic
_____: AV valves open during systole
rapid filling phase
_____: flow into the ventricles slow as pressures equalize.
diastasis
Ventricular end-diastolic volume is ______mL.
110-120
What percent of ventricular filling occurs during diastole?
75%
____: contraction of atria supply remaining 20-30% of end-diastolic volume.
Atrial Kick
SV is ____ mL.
70
Ventricular end-systolic volume is ____ mL.
40-50
____ = SV / end diastolic volume
Ejection fraction
Heart pumps about _____% of EDV with each beat.
60
Work output of the heart is determined by ___ and ____.
pre;pad, afterload
_____= end-diastolic pressure in ventricles
preload
____= pressure in aorta or pulmonary artery
afterload
The venous return and end-diastolic volume regulate cardiac contractility and cardiac output known as?
Frank-Starling mechanism
Venous return is important regulator of ___.
CO
_____= amount of blood that flows from veins bak to right atrium each minute.
Venous return
Sympathetic stimulation increases ____ and contractility.
HR
Sympathetic stimulation can increase HR to ____bpm.
180-200
Parasympathetic stimulation _____ HR.
decreases
Fast HR can _____ CO because there is not enough time for heart to fill during diastole.
decrease
Alterations in ____ and _____ levels can significantly affect cardiac function.
Calcium, potassium
_____ nerve (parasympathetic) has minimal innervation of cardiac muscle.
Vagus
Parasympathetic stimulation deals with ______.
Acetylcholine
What slows HR, decreases rate of SA node discharge, and decreases excitability of fibers between SA node and AV node?
Parasympathetic stimulation
Acetylcholine increases permeability of SA and AV fibers to ____.
potassium
Potassium leaves cells ____ membrane potential.
lowering
Sympathetic stimulation deals with ____.
norepinephrine
What increases HR and contractility, rate of SA node discharge, rate of cardiac impulse conduction in all parts of heart, and force of atrial and ventricular contraction?
sympathetic stimulation
Norepinephrine increases permeability of ___ and _____.
sodium, calcium
Large Q waves greater than .04 seconds in duration may represent _____.
Myocardial Infarction
Flat, downsloping or depressed ST segments may indicate _____.
coronary ischemia
Abnormal T waves (depressed or peaked) can indicate ______ (ischemia or electrolyte abnormalities.
disease
_____: transport blood under high pressure; strong, elastic walls; rapid blood flow.
arteries
_____: act as “control valves”; smooth muscle in vascular walls; relate blood flow to capillaries through vasodilation and vasoconstriction; slower heart rate of slow.
arterioles
______: exchange oxygen, nutrients, and other substances between interstitial space; thin vascular walls.
capillaries
_____: collect blood from capillaries
venuoles
_____: transport blood back to heart; reservoir for blood; thin vascular walls; low pressure; rapid flow compared with capillaries and venuoles.
veins
___ contain some smooth muscle and are innervated by sympathetic fibers.
veins
Venoconstriction can _____ venous return to heart.
increase
Normal mean arterial pressure in systemic circulation?
93 mmHg
______ is difference between systolic and diastolic pressures.
Pulse pressure
Normal capillary pressure in systemic circulation?
17 mmHg
Normal venous pressure in systemic circulation?
0 mmHg at vena cava
Normal systolic pressure in pulmonary circulation?
25 mmHg
Normal diastolic pressure in pulmonary circulation?
8 mmHg
Normal mean arterial pressure in pulmonary circulation?
16 mmHg
Normal capillary pressure in pulmonary circulation?
7 mmHg
____ is determined by pressure gradient and vascular resistance.
Blood flow
______: resistance inversely related to radius of vessel.
Poiseulle’s Law
