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BMS 420 Exam 2
Terms in this set (158)
What classifies a class VI heart murmur?
you can hear/see it without equipment!
What are two examples of a systolic murmur?
Semilunar valve stenosis, AV valve regurgitation
What are two examples of a diastolic murmur?
semilunar valve regurgitation, AV valve stenosis
What characterizes Semilunar valve stenosis?
narrow flow through the aortic or pulmonary valve. Stenosis = flow in the right direction, but narrowed
What characterizes AV valve regurgitation?
blood from the ventricles goes back into the atria during systole (contraction). Leaky valve!!
What are a few consequences of valvular disorders?
1. decreased cardiac output; 2. heart has to work harder to pump blood! 3. enlarged atria; 4. thickening of the ventricles
What is ejection fraction?
SV/EDV; measure of contractility
What are factors affecting heart performance? (CO or SV)
1. heart rate; 2. preload; 3. afterload; 4. contractility
How does the frank-starling law relate to preload, and stretch of the heart?
The greater the stretch on the heart muscle, the greater the preload, the greater the stroke volume. Stretched fibers generate more force!
True or false: the smaller the stretch on the sarcomere, the larger the heart contraction
False!! The larger the stretch on the sarcomere (heart muscle), the greater the contraction
How do increased sarcomere lengths develop more active tension in the heart muscle that produce greater contractions?
1. increased Ca++ affinity of TroponinC, which increases Ca++ sensitivity to myofilaments; 2. Increased tension on stretch-activated Ca++ channels, enhancing Ca++ entry into the cell
What pressure is a good indicator of afterload?
The pressure in the aorta after contraction
What is contractility?
The force generated by the heart under conditions of fixed preload and afterload. Inotropy!!!!!
What hormones increase inotropy?
Norepinephrine and Epinephrine (PUSH EPI!)
How does calcium exit the sarcoplasmic reticulum?
through ryanodine receptor channels (RyR), during Ca++ induced Ca++ release
What hormone stimulated by the sympathetic nervous system initiates cAMP 2nd messenger system?
What receptor does norepinephrine bind to in myocytes?
How does norepinephrine affect the contractile force and velocity of the heart muscle?
Norepinephrine binds to B-adrenergic receptors, activating the cAMP second messenger system. This activates protein kinases which facilitate Ca++ uptake in the cell, increasing cardiac contractile force and velocity.
What do beta blockers do to contractility?
Beta blockers decrease contractility; norepinephrine + epi can't bind
What is phospholamban?
a protein that removes inhibition for Ca++ so it can move across the sarcoplasmic reticulum
How does the cAMP second messenger system facilitate cardiac contraction?
It activates protein kinases that phosphorylate voltage gated Ca++ channels, and phospholamban
What is SERCA?
sarco-endoplasmic reticulum calcium ATPase pump; it regulates contraction force and enhances the relaxation phase
True or false: your ESV is affected by contractility and afterload changes
true! If you have a larger ESV, your contractility is decreased.
What are 6 ways inotropy (contractility) is regulated?
1. phosphorylation of L-type Ca++ channels, enhances permeability; 2. enhanced Ca++ release by SR; 3. enhanced binding to troponin C; 4. myosin phosphorylation via increased cAMP; 5. calcium uptake by SR by the SERCA pump with phosphorylation of phospholamban; 6. Regulation of Na+/Ca++ and ATP dependent Ca++ pump, preventing Ca++ overload
How does H+ affect inotropy?
diminishes inotropy by decreasing the affinity of TroponinC to Ca++
How do you enhance relaxation of the heart?
phosphorylation of phospholamban by PKA as a result of activation of beta-1 adernergic agonists (norepi and epi)
What is another term for relaxation of the heart?
Why is regulation of arterial blood pressure and cardiac output so important?
1. driving pressure maintenance; 2. various activities require various cardiac performance levels; 3. body position changes can affect blood pressure and require reflex action; 4. implications in orthostatic hypotension; 5. implications in hypertension
Where are baroreceptors located?
right atrium, carotid arteries, aortic arch
Baroreceptors work through sympathetic, parasympathetic, or autonomic reflex?
Where are blood chemistry detectors located?
carotid arteries, aorta, medulla
Where are plamsa osmolarity detectors found?
What portions of the brain help regulate cardiac and vascular function depending on afferent input?
Medulla, hypothalamus, and cortex
What factors are stroke volume influenced by?
preload, afterload, contractility, and heart rate
What part of the nervous system primarily controls heart rate?
Autonomic nervous system
Which nervous system (PNS vs SNS) dominates in the heart muscle?
Describe the Parasympathetic nervous system in relation to the heart:
primarily acts at SA/AV node, rapid response and fast decay! Responds quickly. Dominates over the SNS in the heart. generally decreases heart rate
Describe the Sypmathetic nervous system in relation to the heart:
acts at SA/AV node and myocardium, slower to act and slower to cease, uses second messengers (cAMP). Generally increases heart rate! dominated by PNS
The vagus nerve has ____sympathetic affects on the heart
If the vagus nerve and the sympathetic nervous system are innervated simulataneously, what happens to the heart rate?
It decreases! Vagus nerve dominates, and decreases the heart rate.
If you block both the parasympathetic nervous system (using atropine) and the sympathetic NS (using propranolol), what is the response of the heart? What is it's "intrinsic heart rate"?
The heart rate increases!
What acts as a long term regulation of arterial blood pressure?
Renal reflexes (control of fluid balance and blood volume)
How do baroreceptors relay messages, and where do they generally end up?
Electrical signals are sent to the medulla of the brain, specifically the nucleus tractus solidarius
True or False: the higher the arterial pressure, the fewer action potentials sent from the carotid sinus nerve
False! Higher pressure = more action potentials
What is the lower threshold of mean arterial pressure for baroreceptors, and what is the upper threshold? (the pressures where action potential firing will steadily increase from high to low)
40 mm Hg, 150 mm Hg
Where does the carotid sinus have the most effect in local resistance evoked by reduced pressure, and where does it have the least effect?
Local resistance will increase the most in skeletal muscle, less in the kidneys, and least in the splanchnic vessels
What is the relationship between blood pressure and heart rate?
They have an inverse relationship! Increased arterial pressure has a lower heart rate, and vice versa
How do angiotensin, aldosterone, and ADH respond to atrial stretch?
Their release DECREASES
What do baroreceptors typically respond to that indirectly changes arterial blood pressure?
Effective circulating volume! and cardiac output.
Decreased sympathetic activity to the kidney results in:
1. dilation of renal arterioles; 2. increased blood flow to kidney; 3. increased urine output; 4. fluid loss
How does ANP respond to atrial stretch?
Increased release of ANP!
What is right atrial pressure (RAP) dependent on?
What determines the extent of ventricular filling?
Right Atrial Pressure
What is mean systemic filling pressure?
It is the pressure with no heart activity. Usually about 7!
On a vascular function curve, a shift to the right vs. left symbolizes:
Left: increased blood volume, Right: decreased blood volume. (same for mean systemic filling pressures)
On a vascular function curve, an increased slope vs a decreased slope represents:
Increased slope: vasodilation, Decreased slope: vasoconstriction
What effect would a cardiac glycoside have on the cardiac function curve?
positive inotropic effect! shift to the left/increased slope!
How would a decrease in vein compliance affect a normal vascular function curve?
shift to the right, increased blood volume. Decreased compliance = venoconstriction, increased blood pressure, more blood volume into the RA
How would a decrease in systemic vascular resistance affect a normal vascular function curve?
It would increase the slope! Decreased resistance = vasodilation = increased slope
True or false: an increased afterload may result in heart failure
How would increased total peripheral resistance affect the cardiac function and vascular function curves?
Decreased slopes for both. Decreased cardiac function and vasoconstriction! Vasoconstriction = Increased TPR = Increased afterload = decreased cardiac function
How would decreased total peripheral resistance affect a cardiac function and vascular function curve?
Increased slopes for both. Increased cardiac function and vasodilation! Vasodilation = decreased TPR = decreased afterload = increased cardiac function
How does kidney involvement show up on a vascular function curve?
Increased blood volume, shift to the right
Renin is produced by the:
What converts angiotensinogen to angiotensin I?
What converts angiotensin I to angiotensin II?
ACE: angiotensin converting enzyme
What effect do renin, angiotensin, and aldosterone have on arterial blood pressure?
Increase arterial blood pressure!
How do renin, angiotensin, and aldosterone increase arterial blood pressure? (main mechanism)
by increasing blood volume
True or false: the renin-angiotensin-aldosterone system is involved in the short term regulation of arterial blood pressure
FALSE! Long term regulation
How does atrial natriuretic peptide affect arterial blood pressure?
Decreased arterial blood pressure
What is atrial naturetic peptide?
sodium excretion hormone secreted by the right atrium.
If the glomular filtration rate in the kidney increases, what happens to blood volume?
What affect does vasopressin (ADH) have on arterial blood pressure?
Increases arterial blood pressure!
What are the two main mechanisms ADH uses to increase arterial blood pressure?
Vasoconstriction and increased blood volume via renal fluid reabsorption
Where is vasopressin secreted?
The posterior pituitary gland
How are renin/angiotensin/aldosterone, ANP, and ADH regulated?
Via the sympathetic nervous system
How does each vascular bed regulate its own blood supply?
by changing vasomotor tone
What are the 4 basic factors that regulate local blood flow?
1. neural input; 2. metabolites (MAIN ONE!); 3. endothelial factors; 4. myogenic regulation
Which organ has the lowest resting blood flow?
What organ has the highest resting blood flow?
Which organ shows the greatest percent increase from rest to maximal flow? least percent increase?
skeletal muscle; kidney
What is the metabolic theory of blood flow regulation?
based on the release of metabolic vasodilators during increased metabolism, decreasing the vascular resistance, allowing more flow to the metabolically active tissues
How is coronary circulation mainly regulated?
local metabolites! the only way for the heart to receive oxygen and other metabolites is thru the coronary circulation
How do endothelial factors regulate local blood flow?
by affecting the contraction of vascular smooth muscle, or by vasodilation. Tissue injury, nature of blood flow, circulating hormones, lack of oxygen, etc can stimulate production of endothelial factors
What is nitric oxide?
An endothelial factor that causes vasodilation!
Why did Alfred Nobel's factory workers feel angina relief at work?
The bombs they were making released nitric oxide, and caused vasodilation which relieved their pain!
How do myogenic factors regulate blood flow in response to increased pressure?
Myogenic regulation keeps blood flow steady as perfusion pressure increases! The regulatory range is between ~70mmHg to 180 mmHg
Neurogenic effects on the arterioles usually result in...
Where do the coronary arteries originate?
The base of the aorta
When blood from the coronary arteries reach the coronary sinus, what is the oxygen content like?
NO OXYGEN!! black blood. the heart uses a lot of oxygen and depletes the blood of basically all of it
What are the thesbian veins?
drainage from the coronary arteries back into the heart
What is the bohr shift?
increased acidity, decreased binding of oxygen and hemoglobin
Which coronary artery (right or left) shows the most dramatic changes in flow from systole to diastole?
left! blood flow increases dramatically during diastole compared to systole
What determines perfusion pressure for coronary blood flow?
pressure in the aorta and pressure in the coronary sinus
How is blood flow in the endocardium and epicardium different in coronary flow?
Endocardial flow is greater in diastole than systole, and is more prone to myocardial infarction. Epicardial flow is greater in systole than diastole, and is more prone to ischemia
Which dominates in coronary blood flow: metabolite control or parasympathetic factors
What is the effect of acetylcholine on the coronary blood flow?
slows HR, causes vasodilation
If the vagus nerve is stimulated but metabolism is decreased, what is happening to coronary blood flow?
The vagus nerve wants to vasodilate, but decreased metabolism causes vasoconstriction and dominates the vagus nerve
What is the percentage of O2 extraction in the coronary arteries? general circulation?
Coronary arteries: 50-75%, vs general: 25%
If the demand for O2 is greater than the supply, what happens to the coronary arteries?
If the demand for O2 is less than the supply, what happens to the coronary arteries?
What is coronary steal syndrome?
In a diseased heart, blood is diverted from ischemic vessels to the healthy ones; decrease in afterload
What is VEGF?
vascular endothelial growth factor; released from ischemic tissues, leads to angiogenesis (growth of new vessels)
Which tissue is least tolerant to ischemia?
How does the brain safeguard its blood supply?
It controls cardiac output and flow to other organs, always insuring that the brain is the top priority
True or false: cerebral veins have no valves
What are a few examples where intracranial pressure increases?
1. intracranial bleeding; 2. cerebral edema; 3. tumor
What is the effect of increased intracranial pressure?
collapsed veins, decreases cerebral perfusion pressure, reduced blood flow
How does mean arterial pressure relate to cerebral perfusion pressure and intracranial pressure?
MAP = CPP + ICP
What is the major control of cerebral blood flow?
True or false: cerebral blood flow is regulated by strong neural control
False! neural control is weak
How does myogenic autoregulation protect against chronic hypertension or sympathetic nerve stimulation in the brain?
shifts right on the graph, protects endothelial cells from higher pressure and protects against stroke and disruption of the blood-brain barrier
How does resistance in the brain change to control blood flow with hypertension?
Resistance increases in cerebral blood flow, makes you prone to diziness
What effect does increased CO2 have on the cerebral blood flow?
What effect does decreased CO2 have on cerebral blood flow?
vasoconstriction: dizziness after standing up quickly or hyperventilation
True or false: H+ cannot pass through the blood brain barrier
What is the mechanism of vasodilation/vasoconstriction related to CO2 levels?
Increased CO2 decreases the pH, which increases blood flow. Decreased CO2 increases pH, which decreases blood flow
What is the cushing reflex?
Increased blood pressure, bradycardia, and irregular breathing as a result of increased intracranial pressure. It is an attempt to overcome compression and maintain blood flow to the brain through BOTH parasympathetic and sympathetic control
What is the main control for cutaneous (skin) blood flow?
What special circulation is most important for controlling temperature?
skin! local temperature affects tone
What is one main difference between apical skin and nonapical skin?
apical skin can only vasoconstrict, whereas nonapical skin can vasoconstrict and vasodilate
What is a wheal response in the skin?
intense swelling due to increase in capillary permeability
What causes blushing/blanching skin?
cerebral inhibition and stimulation respectively of the sympathetic nervous system
What is the equation for GFR?
GFR = (CO)(percent of CO to kidney)(plasma)(filtration fraction) AKA (CO)(0.2)(1-hematocrit)(FF)
What is occurring at the glomerular capillaries?
What is occurring at the peritubular capillaries?
reabsorption of nutrients
Why do glomerular capillaries have higher pressure than skeletal capillaries?
the afferent arteriole is larger than the efferent arteriole, resulting in higher pressure
Where do most nephrons reside in the kidney?
True or false: filtration is best at low pressures
False! high filtration occurs at high pressure
True or false: the peritubular capillaries prefer lower pressures
True! Lower pressures allow for increased reabsorption
What is a typical filtration fraction?
20%! or 0.2 for calculating GFR
What are the 3 controls of renal blood flow?
1. myogenic autoregulation; 2. tubuloglomerular feedback; 3. sympathetic adrenergic stimulation under hemorrhagic or exercise conditions
How do ACE inhibitors drop the GFR?
People with hypertension are given ACE inhibitors, knocking out Angiotensin II. A-II also acts to constrict the efferent arteriole, which causes a higher pressure in the glomerulus, which increases filtration. Without AII, filtration lessens
When the afferent arteriole is constricted, what happens to GFR, renal plasma flow, and pressure in the glomerulus?
Afferent arteriole constriction = decreased glomerular pressure = decreased glomular filtration rate = decreased renal plasma flow
When the efferent arteriole is constricted, what happens to the glomerular pressure, GFR, and renal plasma flow?
efferent arteriole constriction = increased glomerular pressure = decreased renal plasma flow = increased GFR with increased pressure, and then decreased GFR with decreased plasma flow
As relative arteriole resistance increases, which factor dominates over GFR: glomerular pressure or renal plasma flow?
renal plasma flow!
How does GFR change with mean arterial blood pressure?
It increases as blood pressure increases, but uses myogenic autoregulation to maintain a steady filtration rate from 80 mmHg to 180 mmHg
How does the macula densa function in the kidney?
The macula densa has chemoreceptors that sense the composition of blood being filtered and release paracrines to affect the tone of the afferent arteriole (constrict/dilate)
What circulations are most affected by metabolic control?
coronary, cerebral, and skeletal muscle
What circulations are most affected by sympathetic control?
cutaneous and intestinal
What circulations are most affected by autoregulation?
renal, some coronary and cerebral
What is tubuloglomerular feedback mechanism?
controls GFR via the macula densa sensing filtrate composition and sending paracrine signals to affect afferent arteriole tone
What factors is the heart trying to restore as a result of hemorrhage? How does it accomplish this?
central blood volume, cardiac output, total peripheral resistance, and venous return. Cardiac stimulation, arteriole and venous constriction, and RAS activation
What are the normal (comparative) pressures for arterioles, capillaries, and venules?
arterioles are highest (60 mmHg), capillaries mid (25 mmHg), and venules are lowest (15 mmHg)
Right after a hemorrhage, before compensatory reflex kicks in, what are arteriole, capillary, and venule pressures like?
What do compensatory reflexes do to the arteriole, capillary, and venule pressures and resistance?
sympathetic vasoconstriction increases arteriolar and venule resistance, increases all 3 pressures
After hemorrhage persists, what happens to compensatory mechanisms?
vasoconstriction declines due to receptor fatigue/neurotransmitter depletion and as ishemia worsens. Metabolites increase
What is capillary refill?
During hemorrhage, capillary blood pressure can get so low that you start reabsorbing fluid and nutrients from the tissues into the capillaries
What constitutes heart failure?
insufficient blood flow, or sufficient blood flow with an abnormally high preload
What two factors directly influence blood pressure?
cardiac output and peripheral resistance
What are four factors that influence peripheral resistance?
circulating regulators (angiotensin II, catecholamines), Direct innervation (alpha and beta receptors), local regulators (vasodilators and vasoconstrictors), and blood viscosity (hematocrit)
What are primary blood vessel abnormalities in hypertension in relation to neurotransmitters/hormones?
decreased nitric oxide secretion, increased endothelin production, Ca++ or Na+/K+ channel defects, hyperresponsiveness to catecholamines
How do cardiac output and total peripheral resistance change with age?
Cardiac output decreases, which causes total peripheral resistance to increase (maintenance of blood pressure)
What are some long term consequences of hypertension?
heart failure, myocardial ischemia and infarction, aortic aneurysm and dissection, stroke, nephrosclerosis and renal failure, retinopathy
What is the difference between aneurysm and dissection?
Aneurysm is a sac or bulge on the aorta due to weakening of the vessel wall, and dissection is when a blood clot disrupts flow and causes damage to the vessel wall
What are the six principle mechanisms of cardiac dysfunction?
1. pump failure; 2. obstruction of flow; 3. Regurgitant flow; 4. Shunted flow; 5. disorders of cardiac conduction; 6. Rupture of the heart or major vessel
What is ischemic heart disease?
coronary heart disease, imbalance between supply and demand of oxygen in the heart
What are the different forms of angina?
Stable: chronic pattern, predictable; Variant: pain at rest due to vasospasm, no athlerosclerosis; Unstable: increases in frequency and severity, dangerous blood clots
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