Cardiac Physiology and Lymphatics Flashcards
What does the circulatory system deliver?
Oxygen, nutrients, hormones, immune cells, other substances
What does the circulatory system remove?
Waste products via lungs, kidneys, digestive tract
What circulatory structures are involved in plumbing?
heart wall, chambers of the heart, heart valves, great vessels, peripheral vascular
What are the functions of the circulatory structures?
control blood flow and maintain intercardiac pressures
What is the epicardium?
smooth surface against pericardial sac, lessens friction
What is the myocardium?
cardiac muscle/myocytes, varying thickness
What is the endocardium?
continuous with the endothelium lining vasculature
What are the 3 layers of the heart enclosed in?
pericardium
What is the pericardium?
double-walled sac that prevents heart displacement, physical barrier for infection and inflammation, protection
How much pericardial fluid is in the pericardium?
20 mL
What does pain and mechanoreceptors cause?
changes in blood pressure and heart rate
The right atrium and right ventricle have ____ pressure going to the _____.
low, lungs
The left atrium and left ventricle have ____ pressure that is _____.
high, systemic
What is the thickest myocardium?
left ventricle
The left ventricle pumps against ____ resistance of____ mm Hg.
most, 92
The right ventricle is ____, pumping against ___ mm Hg.
thinner, 15
______ have thinnest walls with ____ ____ resistance to pump against.
Atria, very little
Right heart receives ______ blood from _____ and ______ vena cava.
deoxygenated, superior, inferior
Blood leaves the right ventricle through ____ artery (branches from L and R).
pulmonary
Oxygenated blood back to left atrium through __________.
4 pulmonary veins
Oxygenated blood leaves left ventricle into the aorta.
aorta
What are the 4 main valves that ensure one way flow and pressure gradients?
2 atrioventricular valves and 2 semilunar valves
Which AV valve has the largest diameter?
right (tricuspid) valve
What makes up one cardiac cycle?
ventricular contraction (systole) + relaxation (diastole)
What is diastole?
relaxation of the heart, allowing the heart chambers to fill
What is systole?
propels blood into pulmonary and systemic circulation
Ventricles have _____ pressures in systole than atriums do.
higher
What supplies blood to the left atrium and lateral wall of left ventricle?
circumflex artery
Coronary arteries are ____ in women.
smaller
What are collateral arteries?
connections between branches of same coronary artery or connections with left and right CAs
How do new collateral arteries form?
in response to shear stress (inc blood flow speed near stenosis) or production of growth factors and cytokines
What do collateral arteries do?
arterio/angiogenesis, supplying blood and oxygen to myocardium that has become ischemic following stenosis of 1 or more coronary arteries
Alterations of cardiac muscles affect blood flow in the _____.
capillaries
Ventricular hypertrophy causes _____ oxygen delivery.
decreased
Veins drain cardiac circulation into visceral pericardium and then into _________ and _______ on posterior heart.
great cardiac vein, coronary sinus
What do arterial vessels and veins both have?
tunica intima (innermost), tunica media (middle), tunica externa (outermost)
Tell me about arterial vessels.
thick-walled, pulsating, carries blood away from heart
What are elastic arteries?
They have thick tunica media and are located close to heart. They stretch and recoil to maintain blood pressure.
What are muscular arteries?
medium and small arteries further from heart, distribution and blood flow control, vasoconstriction and vasodilation of lumen
Tell me about veins.
thin walled, larger diameter, more numerous, do not recoil as much or as rapidly after distension
Valves facilitate _____ flow.
one-way
What is the endothelium?
blood vessel lining, sometimes considered a separate endocrine organ
What are the functions of the endothelium?
substance transport, coagulation, anti-thrombogensis, fibrinolysis, immune function, tissue and vessel growth, wound healing, contraction and relaxation of vessels
When endothelial damage or dysfunction occurs, we see most common and serious cardio disorders such as ________ and _____.
hypertension, atherosclerosis
What is the body’s natural pacemaker?
sinoatrial (SA) node
What is the process of action potentials?
action potentials –> electrical impulses –> intracellular process= muscle shortening/contraction (systole)
Between action potentials, muscles relax known as _____.
diastole
Do action potentials move fast or slow?
fast, organized and sequential firing (atria first, then ventricles)
The heart has sympathetic and parasympathetic wiring but can function in absence of those known as _____.
automaticity
What happens during Phase 0 of action potential?
Na+ influx, depolarization
What happens during Phase 1 of action potential?
K+ influx, inactive Na+ channels, slight repolarization
What happens during Phase 2 of action potential?
plateau, Ca2+ influx, slows repolarization
What happens during Phase 3 of action potential?
dec in Ca2+, inc in K+ efflux, repolarization
What happens during Phase 4 of action potential?
resting membrane potential
Which branch of autonomic nervous system is fight and flight?
sympathetic
Which branch of autonomic nervous system is rest and digest?
parasympathetic
Cardiac innervation consists of ____ and _____ nerves.
sympathetic, parasympathetic
What are sympathetic nerves?
increases electrical conductivity and the strength of myocardial contraction
What are parasympathetic nerves?
slows conduction of action potentials through heart and reduces strength of contration
Stimulation/agonism of B1 and B2 adrenergic receptors…
increases heart rate (chronotropy) and force of myocardial contraction (inotropy)
Positive chronotropy= _______ heart rate, negative chronotropy= _____ heart rate
increased, decreased
Positive inotropy= _______ force of contraction, negative inotropy= _____ force of contraction
increased, decreased
What is the function of B3 receptors?
dec myocardial contractility (neg inotropic effect), may provide “safety mechanism” to prevent overstimulation of heart by sympathetic nervous system
Norepinephrine binds with a1 receptors in ____ and _______ arteries for smooth muscle contraction and vasoconstriction.
systemic, coronary
Norepinephrine binds with a2 receptors in ____ and _______.
brain (modulates sympathetic outflow), periphery (controls sympathetic tone)
What factors affect heart rate?
autonomic innervation, hormones, fitness levels, age
What factors affect stroke volume?
heart size, fitness levels, gender, contractility, duration of contraction, preload (EDV), afterload (resistance)
Stroke volume=
EDV-ESV
Cardiac output=
HR x SV
What is the average heart rate in healthy adults?
60-80 bpm
What is stroke volume?
volume of blood pumped out of left ventricle per contraction
What is end-diastolic volume?
during diastole, volume of ventricles inc from 70-120 mL
What is end-systolic volume?
volume of blood remaining in the ventricle after systole (usually 40-50 mL)
What is cardiac output?
the volume of blood flowing through either the systemic or pulmonary circuit (L/min)
What is normal cardiac output at rest?
5 mL/min
What is ejection fraction?
EF= SV/EDV, %, indicator of ventricular function, normal is 66% for women and 58% for men
What is preload?
volume inside the ventricle at end of diastole, same as ventricular EDV and ventricular EDP
What 2 primary factors determine preload?
amount of venous return to ventricle, blood left in ventricle after systole or end-systolic volume
When preload exceeds physiologic range, further muscle stretching causes a ______ in ______.
decline, cardiac output
When is preload increased?
hypervolemia, regurgitation of cardiac valves, heart failure
What is the Frank-Starling Law of the heart?
volume of blood at end of diastole, major way that RV and LV maintain equal minute outputs despite stroke (beat) output variation
Myocardial stretch determines the force of _______ __________.
myocardial contraction (more stretch= inc force of contraction)
What is Laplace’s Law?
contractile force within a chamber depends on radius of chamber and thickness of its wall
Smaller chambers and thicker chamber walls equals ______ contraction force.
increased
In ventricular dilation, the force needed to maintain ventricular pressure _______ available contractile force.
lessens
What is afterload?
resistance to ejection during systole
______ is a good index of afterload for the left ventricle.
aortic systolic pressure
Decreased afterload means
heart contracts more rapidly
Increased afterload means
slow contractions and increased workload
Volume of blood ejected during systole increases with increase in _________.
contractility
What determines the force of the contraction?
changes in stretching of ventricular myocardium caused by changes in ventricular volume (preload), alterations in nervous system input to ventricles, adequacy of myocardial oxygen supply
What are positive inotropic agents?
inc force of contraction: norepinephrine, epinephrine
What are negative inotropic agents?
dec force of contraction: acetylcholine released from vagus nerve
Hypoxia ___________ contractility.
decreases
What is arterial blood pressure?
reflects ejection of blood from LV into aorta
What is pulse pressure?
difference between systolic and diastolic pressure
What is mean arterial pressure (MAP)?
average arterial pressure throughout one cardiac cycle, systole, and diastole
MAP=
DP+ 1/3 (SP-DP)
What is pressure?
force exerted on a liquid per unit area
What is resistance?
opposition to blood flow, increases with turbulence (think: plaques)
_____ and _______ contribute to resistance.
diameter, length of blood vessels
What is velocity?
the distance blood travels in a unit of time
Thick fluids move more ______ and cause ________ resistance to flow than thin fluids.
slowly, greater
High hematocrit _______ flow through blood vessels.
reduces
What is vascular compliance?
increase in volume a vessel can accommodate for given an increase in pressure
_____ is the opposite of compliance.
stiffness
______ are more compliant than arteries.
veins
What is laminar flow?
occurs when concentric layers of molecules move “straight ahead”
What is turbulent flow?
occurs where flow is obstructed, vessel turns, or blood flows over rough surfaces, producing a murmur
What is vasoconstriction?
occurs via chemicals or neurotransmitters such as endothelin
What is endothelin?
powerful vasoconstrictor found in vascular endothelium
What is vasodilation?
occurs via chemicals or neurotransmitters such as nitric oxide, histamine, kinins
What is nitric oxide?
secreted by endothelial cells, keeps vessels open
Vascular smooth muscle cells produce
vasoconstriction or dilation of blood vessels
Depolarization depends on
extracellular calcium entering through calcium channels
Sympathetic nervous system control of smooth muscle occurs by
opening or closing of calcium channels
Alpha-adrenergic receptors are
excitatory
When alpha-adrenergic receptors are stimulated, it causes channels to ___ and cause _______ .
open, vasoconstriction
Beta-adrenergic receptors are
inhibitory
When beta-adrenergic receptors are stimulated, it causes channels to ___ and cause _______ .
close, vasodilation
Organs and tissues can regulate their blood flow based on ______ needs.
metabolic
What is autoregulation?
local control mechanism that automatically adjusts tissue blood flow independent of systemic factors
Blood flow to kidneys, heart, and brain remains constant over wide range of BP because the organs __________.
adjust to BP
What is metabolic control of autoregulation?
smooth muscle contraction and relaxation occur in response to local tissue factors like lack of oxygen, inc hydrogen, excess CO2, lactic acid
When the local tissue factors are released, what happens?
immediate vasodilation of arterioles serving metabolically deprived tissues
What is a function of endothelial cells?
to produce factors that affect the relaxation or contraction of arterial wall
What is the most important endothelial cell?
nitric oxide
Tell me about nitric oxide.
released continuously in body, can be released due to stress on endothelium, inhibits platelet aggregation, can be stimulated by endothelial agonists (acetylcholine, bradykinin, histamine, thrombin)
What is humoral control of blood flow?
involves effect of vasodilator and vasoconstrictor substances in blood
What are norepinephrine and epinephrine?
vasoconstrictor hormones released from sympathetic nerve endings
What is angiotensin II?
powerful vasoconstrictor produced in the RAAS, increased PVR/BP
What is histamine?
powerful vasodilator, acts on arterioles, derived from mast cells in injured tissues
What is serotonin?
released from aggregating platelets during clotting process, vasoconstriction and plays role in control of bleeding
What is bradykinin?
released from globulin kininogen, powerful vasodilation of arterioles
What are prostaglandins?
synthesized from parts of the cell membrane, released in response to tissue injury, produce vasodilation and constriction
What are baroreceptors?
chemosensitive cells that respond to changes in pCO2 and pO2 and pH levels (hydrogen ion) to regulate BP
What is atrial natriuretic peptide (ANP)?
hormone secreted by atria of the heart in response to stretch
How does ANP lower blood pressure?
causes vasodilation and stimulates kidneys to excrete more water and Na+ (lowers BP by reducing blood volume)
When is ANP increased significantly?
in exacerbations of heart failure since it is trying to get rid of extra fluid with limited success
What does the renin-angiotensin-aldosterone system of the kidneys regulate?
blood volume
In response to decreased blood pressure or fluid volume, the _______ cells in the kidneys secrete ____ into the blood.
juxtaglomerular, renin
Renin converts the plasma protein angiotensinogen into _____.
angiotensin I
How is angiotensin I converted to angiotensin II?
by enzymes like angiotensin converting enzyme ACE from lungs
What does angiotensin II do?
constricts blood vessels throughout the body (raising blood pressure by increasing resistance to blood flow)
Constricted blood vessels ____ the amount of blood delivered to the kidneys. This ______ kidneys’ potential to excrete water.
reduce, decreases
BP is raised by ______ blood volume.
increasing
Angiotensin II also stimulates ______ to secrete aldosterone.
adrenal cortex
What is aldosterone?
a hormone that reduces urine output by increasing retention of H2O and Na+ by the kidneys, raises blood pressure by inc blood volume
What is another name for vasopressin?
antidiuretic hormone
Vasopressin is released from the _______ when BP or volume is down.
posterior pituitary gland
How does vasopressin raise blood pressure?
It stimulates the kidneys to retain H2O (inc blood volume).
Vasopressin is secreted when we have increased body fluid _____. It will ____ hepatic vasculature over short-term in another attempt to ____ BP.
osmolality, constrict, increase
How does nicotine affect blood pressure?
It raises BP by stimulating sympathetic neurons to inc vasoconstriction and by stimulating the adrenal medulla to inc secretion of epinephrine and norepinephrine.
How does alcohol affect blood pressure?
It lowers BP by inhibiting vasomotor center (causing vasodilation) and by inhibiting the release of ADH (inc H2O output, which dec blood volume).
Increased blood volume=
inc BP (to a point), arterioles and vessels will constrict to protect end organ –> leads to high PVR and BP
If BP is rising…
baroreceptors stretch> inc central activity (inc impulses to brain)> inc parasympathetic signals > dec sympathetic signals> slows HR > vasodilation occurs > dec BP
Tell me about short term (acute) control of blood flow.
regulate blood vessel diameter, change HR, change contractility (usually done through neural or hormonal means)
Tell me about long term (chronic) control of blood flow.
regulate blood volume (usually done via kidney)
The ____ system is considered part of the circulatory system.
lymphatic
____ of fluid filters out of venous capillaries, carried by lymphatic vessels to chest to enter venous circulation.
~3L
What is the lymph system?
pumpless system (valves ensure one-way flow), contains mostly water, some proteins, lymphocytes, and antigen-presenting cells
What is the role of the lymphatic system?
immune function, fluid balance, transport of lipids, hormones, and cytokines
____ and _____ drain into the R and L subclavian veins.
R and L lymphatic ducts
What is the primary role of lymph nodes?
filtration
What else are lymph nodes involved in?
phagocytosis, delivery of lymphocytes
