Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
140 Cards in this Set
- Front
- Back
|
Describe the basic structure of a cardiovascular system.
|
Heart (pump), blood vessels (tubes), and blood (fluid)
|
|
|
List at least 5 substances transported by the blood.
|
1) Oxygen
2) Nutrients and water 3) Wastes 4) Immune cells, antibodies, clotting proteins 5) Hormones 6) CO2 7) Heart 8) |
|
|
What are the key functions of the cardiovascular system?
|
1) Pick up O2 and nutrients and then deliver to body's cells and remove cellular wastes and heat for excretion
2) Cell-to-cell communication 3) Defending the body against foreign invaders |
|
|
How do arteries differ from veins?
|
Arteries are blood vessels that carry blood away from the heart
Veins return blood to the heart |
|
|
What ensures one-way flow of blood through the system?
|
System of valves in the heart and veins
|
|
|
LOOK: DIAGRAM OF HEART
|
Fig. 14.7g
|
|
|
LOOK: DIAGRAM OF CIRCULATION THROUGH BODY
|
Fig. 14-1, Table 14.1
|
|
|
Name the vessels that supply blood to heart muscle.
|
Coronary arteries, veins -> coronary sinus (Right Atrium)
|
|
|
LOOK: Trace a drop of blood from the left ventricle to the stomach and back to the left ventricle.
|
Look at fig. 1
|
|
|
Compare the pulmonary circulation with the systemic circulation.
|
PULMONARY:
Blood going to lungs: less O2 From right ventricle -> lungs -> left atrium SYSTEMIC: Blood going to cells: O2 Blood vessels that carry blood from left side of heart -> tissues -> right side |
|
|
What is a portal system? Name the 3 portal systems of the body.
|
Portal system: specialized region of the circulation consisting of 2 capillary beds directly connected by a set of blood
1) Hepatic portal vein: digestive -> liver to process nutrients and detoxify foreign substances 2) Kidneys 3) Hypothalamic-hypophyseal portal system (hypothalamus and anterior pituitary) |
|
|
How does the heart create a region of higher pressure?
|
Contract; closed loop
|
|
|
As blood moves away from the heart, what happens to the blood pressure?
|
Friction between fluid and blood vessel walls
|
|
|
Where is highest blood pressure found? Lowest?
|
Highest pressure found in aorta and systemic articles as they receive blood from left ventricle
Lowest: Venae cavae, just before going to right atrium |
|
|
What units are used to measure pressure in CV?
|
mm Hg (millimeters of mercury)
|
|
|
How are myocardical contractile different from autorhythmic cells?
|
Autorhythmic: pacemakers that set the rate of heartbeat; are smaller; contain few contractile fibers; no organized sarcomeres; do not contribute to contractile force of the heart
|
|
|
What is pacemaker potential?
|
Unstable membrane potential b/c it never "rests"
Gives myocardial autorhythmic cells the unique ability to generate action potentials spontaneously in the absence of input from nervous system Always depolarize to threshold |
|
|
LOOK: Map or diagram the Ca2+ induced Ca2+ release mechanism for contraction in contractile myocardium. Is this more similar to skeletal or smooth muscle?
|
More similar to skeletal muscle, because first there's a depolarization, then RyR channels are opened to allow Ca2+ in from the cytoplasm; Ca2+ binds to troponin to allow actin-myosin binding; Ca2+ taken into sarcoplasmic reticulum by Ca2+ ATPase
|
|
|
How is Ca2+ removed from the cytoplasm of a cardiac muscle cell?
|
1) Ca2+ - ATPase takes Ca2+ into sarcoplasmic reticulum
2) Each Ca2+ moves out of the cell against its electrochemical gradient in exchange for 3 Na+ |
|
|
How do cardiac muscle cells created graded contractions?
|
Graded contractions: which the fiber varies the amount of force it generates; the force generated by cardiac muscle is proportional to the number of active crossbridges, determined by how much Ca2+ is bound to troponin.
If Ca2+ cytosolic concentrations are low, some crossbridges aren't activated and contraction force is small. Sarcomere length at the beginning of contraction: tension generated is directly proportional to the initial length of the muscle fiber (how much blood is in there) |
|
|
What causes the unstable membrane potential in myocardial autorhythmic cells?
|
Channels: If cell membrane potential is -60, If channels permeable to both K+ and Na+ open
1) Na+ influx > K+ efflux, so depolarizes 2) Then If close and some Ca2+ open, which continues the depolarization 3) As move towards threshold, then Ca2+ opens also, causing steep depolarization 4) Then slow k+ channels open at peak of action, allow K+ to go out (repolarization) |
|
|
Compare the movement of ions during myocardial contractile and myocardial autorhythmic action potentials.
|
Contractile: Depolarization SOLELY by Na+; repolarization by down Na and K in cell and up Ca2+; finally, K+ channels open and K+ goes out cell and Ca2+ exits
Autorhythmic: dep: Na+ in, then Ca2+ in; rep: K+ out, and Ca2+ channels |
|
|
How do catecholamines affect the rate of depolarization in pacemaker cells? Describe in terms of ion movement. To which receptor are the catecholamines binding?
|
Catecholamines speed up heart rate; they increase ion flow through both If and Ca2+ channels, speeding up rate of depolarization, causing cell to reach threshold faster and increasing the rate of AP firing; they exert their effect by binding to and activating B1= adrenergic receptors on autorhythmic cells, and use cAMP second messenger system to alter transport properties of the ion channels; when cAMP binds to open If channels, they remain open longer
|
|
|
How does ACh affect the rate of depolarization in pacemaker cells? Describe in terms of ion movement. To which receptor does ACh bind?
|
Slows heart rate
Activates muscarinic cholinergic receptors that influence K+ and Ca2+ channels in the pacemaker cell; K+ permeability increases, hyperpolarizing the cell so that the pacemaker potential begins at a more negative value; at the same time, Ca2+ permeability of the pacemaker decreases. Decreased Ca2+ permeability slows the rate at which the pacemaker potential depolarizes Delay onset of the action potential in the pacemaker and slows heart rate |
|
|
READING QUESTIONS FOR LECTURE CV2
14.26: Where do electrical signals in the heart originate? |
Action potential in an autorhythmic cell -> depolarization spreads rapidly to adjacent cells through gap junctions in the intercalated disks -> wave of contraction from atria -> ventricles
|
|
|
What are intercalated disks?
|
They contain desmosomes that are strong and transfer force from cell to cell, and gap junctions that allow electrical signals to pass rapidly from cell to cell
|
|
|
What anatomical feature of myocardial cells allows coordinated contraction?
|
Desmosomes
|
|
|
What cell structures allow electrical signals to spread quickly to adjacent cells?
|
Gap Junctions
|
|
|
What is the purpose of the AV node delay?
|
Allow the atria to complete their contraction before ventricular contraction begins
|
|
|
Define a cardiac cycle.
|
Single contraction-relaxation cycle.
|
|
|
What is an electrocardiogram?
|
Place electrodes on skin's surface and record the electrical activity of the heart
|
|
|
What information does an ECG show?
|
Summed electrical potentials generated by all cells of the heart
|
|
|
What is Einthoven's triangle?
|
Hypothetical triangle created around the heart when electrodes are placed on both arms and left leg
ECG is recorded from 1 lead at a time; 1 electrode = positive; the other, negative. Third electrode is inactive. If net change movement through heart is toward negative electrode, wave points downward |
|
|
Name the waves of the ECG, tell what electrical event they represent, and with what mechanical event each wave is associated.
|
3 Major Waves:
1) P wave: depolarization of the atria. 2) PQ or PR: conduction through AV node and AV bundle ATRIA CONTRACT 3) Q wave: conduction through bundle branches 4) R wave: conduction through Purkinje fibers 5) S wave: conduction through Purkinje and beginning of contraction of ventricles 6) ST: Contraction of ventricles 7) T: Ventricular repolarization 8) rest of T: the end Can see how mechanical events of cardiac cycle lag behind electrical signals |
|
|
How does an ECG differ from a single myocardial contractile cell action potential?
|
ECG: summed electrical activity of all cells, 1 mV change
1 single myocardial action potential: voltage change is much greater (110 mv); 1 steady dep, and still always sloping downard repol; nothing before or after |
|
|
What is a normal range for heart rate?
|
60-100 beats per minute
|
|
|
When looking at an ECG, how can you determine heart rate?
|
Heart rate is normally timed either from the begining of one P wave to the beginning of the next P wave or from the peak of one R wave to the next peak
|
|
|
What electrical event is taking place during the P-R segment on an ECG?
|
Conduction through AV node and AV bundle
|
|
|
Explain how you would identify an arrhythmia on an ECG
|
Can result from a benign extra beat or from more serious conditions such as atrial fibrillation, in which the SA node has lost control of the pacemaking
Too many P or T waves, or not enough distinction between P/T waves and QRS waves; rate too fast or slow; |
|
|
Define systole and diastole.
|
Diastole: time when cardiac muscle relaxes
Systole: Time during muscle contraction |
|
|
Compare and contrast the AV and semilunar valves.
|
Atrioventricular valves: between atria and ventricles
Semilunar valves: between ventricles and arteries |
|
|
What are the chordae tendineae and what is their function? How are the chordae tendineae related to papillary muscles?
|
Chordae tendineae: Collagenous tendons that fasten to edges of valve flaps and moundlike extensions of the papillary muscles
|
|
|
Is the heart in atrial and ventricular systole at the same time? Explain.
|
No; first, the atria are in systole, then the ventricles.
|
|
|
As the ventricles relax, which valves open? Is blood flowing into the heart? Which chambers?
|
Because the ventricular pressure starts increasing, past the pressure of the arteries, blood starts to flow backward and then the semilunar valves close; then, isovolumic ventricular relaxation; then P becomes less than atrial pressure and the AV valves open; blood that has been accumulating in the atria during ventricular contraction rushes into ventricles
|
|
|
In a person at rest, how much of ventricular filling depends on atrial contraction?
|
20%
|
|
|
Is there a valve between the atria and venae cavae or pulmonary vein?
|
No
|
|
|
What electrical event precedes ventricular systole?
|
Depolarization wave through conducting cells of AV node, and then rapidly down the Purkinje fibers
|
|
|
As the ventricles contract, why do the AV valves close?
|
Spiral bands of muscle squeeze blood upward toward base, and blood pushing against the underside of the AV valves forces them closed so that blood cannot flow back into the atria
|
|
|
What creates the heart sounds?
|
1st: Vibrations following closure of AV valves create first heart sound
2nd: Vibrations created by semilunar valve closure |
|
|
What happens during isovolumic ventricular contraction?
|
No volume change, but pressure increases until it is higher than that of the aorta
|
|
|
What happens to pressure within the ventricles during isovolumic ventricualr contraction?
|
Increases
|
|
|
What is happening to the atria during isovolumic ventricular contraction?
|
Atria muscle fibers are repolarizing and relaxing; when atrial pressure falls below that in the veins, blood flows from the veins into atria again
|
|
|
What causes the semilunar valves to open, allowing blood to be ejected into the arteries?
|
The semilunar valves open because ventricles contract and P increases
|
|
|
Why do the semilunar valves close?
|
At the end of ventricular ejection, ventricles being to repolarize and relax; P falls below the pressure in arteries; backflow of blood fills cusps of semilunar valves, forcing them into closed position
|
|
|
When in the cardiac cycle do the AV valves open?
|
After isovolumic ventricular relaxation, ventricular relaxation causes ventricular pressure to become less than atrial pressure
|
|
|
Define end-diastolic volume (EDV) and end systolic volume (ESV).
|
EDV: Maximum amount of blood that can fill at the end of ventricular relaxation
ESV: Amount of blood left in ventricle at the end of contraction (min amount of blood in ventricles) |
|
|
Answer the following questions using the P-V loop shown in Fig. 14.25.
1) At point A, is atrium relaxed or contracting? |
dfd
|
|
|
What is stroke volume? Units?
|
Amount of blood pumped by one ventricle during a contraction. It is measured in mL per beat.
|
|
|
How do you calculate stroke volume?
|
EDV - ESV = volume of blood before a contraction - volume of blood after a contraction
|
|
|
If the end-diastolic volume increases and the end-systolic volume decreases, has the heart pumped more or less blood?
|
More
|
|
|
Define cardiac output.
|
A way to measure the effectiveness of the heart as a pump, the volume of blood pumped by one ventricle in a given period of time.
zBecause all blood that leaves the heart flows through the tissues, cardiac output is an indicator of total blood flow through the body. beats per minute x mL per beat (Heart rate x stroke volume) |
|
|
What are average values for stroke volume and cardiac output in a 70 kg man at rest?
|
Heart rate = 70 beats per minute
Cardiac output: 5 liters/minute Stroke volume: 0.071 Liters/beat |
|
|
Explain the antagonistic control of heart rate by sympathetic and parasympathetic neurons.
|
Parasympathetic: slows down heart rate
Sympathetic: speeds it up Tonic control of heart rate: dominated by parasympathetic branch So increase heart rate? Decrease parasympathetic output; Or increase heart rate above intrinsic rate? INcrease sympathetic output (norepi on B1 receptors) |
|
|
If you were to block all autonomic input to the heart, what would happen to the heart rate?
|
It would be 90-100 betas per minute.
|
|
|
At the SA node, what are the parasympa and sympa receptors and neurotransmitters?
|
SYMPA: norepinephrine, on B1 receptors. They increase Na+ and Ca2+ influx, increasing the rates of depolarization, increasing heart rate.
Parasympathetic: Acetylcholine and muscarinic receptors; increase K+ efflux and decrease Ca2+ influx, hyperpolarizing cell and decreasing rate of depolarization, decreasing heart rate |
|
|
Describe the effects of autonomic modulation on conduction through AV node.
|
Acetylcholine secreted by parasympathetic neurons slows the conduction of action potentials through the AV node, increasing AV node delay
VS. Catecholamines epinephrine and norepi enhance conduction of AP through AV node |
|
|
What factors affect force of contraction?
|
Stroke volume (vol of blood pumped per ventricle per contraction), which is influenced by lenght of muscle fibers at the beginning of contraction (EDV, volume of blood at the beginning of contraction) and the contractility of the heart (intrinsic ability of a cardiac muscle fiber to contract at any given fiber length and is a function of Ca2+ interaction with contractile filaments)
|
|
|
Define contractility.
|
Intrinsic ability of a cardiac muscle fiber to contract at any given fiber length and is a function of Ca2+ interaction with contractile filaments.
|
|
|
State the Frank-Starling law of the heart.
|
Stroke volume is proportional to EDV. As more blood enters the heart, the heart contracts more forcefully and ejects more blood. (Heart pumps all the blood that returns to it).
|
|
|
What is venous return? What cardiac volume does it determine?
|
Venous return is the end-diastolic volume, the amount of blood that enters the heart from the venous circulation.
|
|
|
What are the 3 factors that affect venous return?
|
1) Contraction of compression of veins returning blood to the heart (skeletal muscle pump)
2) Pressure changes in the abdomen and thorax during breathing (respiratory pump) 3) Sympathetic innervation of the veins |
|
|
Describe the skeletal muscle and respiratory pumps.
|
Skeletal muscle pump: Skeletal muscle contractions that squeeze veins and push blood toward heart (like exercise)
Respiratory pump: increased pressure in abdominal veins and decreased pressure in thoracic ceins enhances venous return from vena cava during inspiration |
|
|
What is an inotropic agent?
|
Any chemical that affects contractility
|
|
|
What effect does a positive inotropic agent have on the heart? Name two agents that create a positive inotropic effect.
|
1) Positive: Increases contractility
ex) norepi and epi, digitalis |
|
|
How do catecholamiens enhance the rate and force of cardiac muscle contraction?
|
SEE FIG
|
|
|
What kind of receptors are found on the myocardium? What is the second messenger system?
|
Adrenergic receptors (B1) -> cAMP second messenger system to phosphorylate voltage-gated Ca2+ channels and phospholamban
|
|
|
How do cardiac glycosides enhance contractility? What are the therapetuic uses of cardiac glycosides?
|
Include oubain, which slows Ca2+ removal...how? Inhibit Na+ K+ ATPase, decreasing Na+ gradient for Na+/Ca2+ secondary active transporter, inhibiting release of Ca2+ from cell, increase myocardial contractions
|
|
|
Define and describe afterload.
|
Combined load of EDV and arterial resistance during ventricular contraction is known as afterload
|
|
|
What is the ejection fraction? What are normal ejection fraction values for our 70 kg man?
|
Ejection fraction: Percentage of EDV ejected with one contraction; it's usually 52%, but can increase to 74% with exercise.
|
|
|
What is the functional importance of nonconducting tissue between the atria and ventricles?
|
jjj
|
|
|
What is the driving pressure?
|
Pressure created in the ventricles that is the force that drives blood through the blood vessels.
|
|
|
What happens to the pressure when the heart relaxes or the blood vessels dilate?
|
When the heart relaxes, then the blood pressure in them falls; if blood vessels constrict, blood pressure increases.
|
|
|
What is a pressure gradient?
|
Flow through the tube is directly proportional to the pressure gradient (delta P):
FLOW PROPORTION TO P1 - P2 Higher the pressure gradient, the greater the flow. |
|
|
Define resistance. Express this relationship between resistance and flow mathematically.
|
Resistance: Tendency of the CV system to oppose blood flow
FLow is inversely proportional to flow. |
|
|
Name the 3 parameters that influence resistnace for fluid flowing through a tube.
|
1) Length of the tube (like length of straw)
2) Viscosity (milkshake more viscous than water) 3) Radius (bigger straw -> easier to get things through, vs. smaller straw) |
|
|
Name Poiseuille's Law.
|
R equal to 8 Ln / pi r^4
|
|
|
In humans, which of the factors of Poiseulle's law are constant and play a significant role in determining resistance to blood flow?
|
Length is determined by anatomy of system and essentially constant
Blood viscosity: constant also CHANGES IN RADIUS AFFECT RESISTANCE |
|
|
Explain vasoconstriction and vasodilation in terms of diameter and resistance.
|
Vasoconstriction: decrease in blood vessel diameter, and thus increase resistance, thus decreasing flow.
Vasodilation: increase diameter, decrease resistance, increase flow. |
|
|
What is the difference between flow (flow rate) and the velocity of flow?
|
Flow rate: FLOW (actually)
L/min or cm^3 per minute Velocity of flow: Q/A, or cm/min |
|
|
What factors have the biggest influence on the flow rate? On the velocity of flow?
|
FLOW RATE: Pressure gradient, resistance
Velocity of flow: Affected by flow rate, and varies inversely with the diameter. Velocity is faster in narrow sections and slower in wide sections |
|
|
Write the equation that expresses the relationship between flow rate (Q), velocity of flow (v), and cross sectional area (A) of a tube.
|
v = Q / A
|
|
|
What is mean arterial pressure (MAP) and what are the two parameters influencing MAP?
|
MAP, primary driving force for blood flow, influenced by cardiac output and peripheral resistance (resistance of the blood vessels to blood flow through them).
|
|
|
Name the 4 tissue layers found in blood vessel walls, starting with the layer closest to the lumen.
|
Endothelium -> Elastic tissue -> Smooth muscle -> Fibrous tissue
|
|
|
Describe key physical differences of the aorta, major arteries, arterioles, capillaries, venules, and veins.
|
Aorta: Stiff, springy
Arteries: Stiff, springy, thick smooth layer, large amount sof elastic and fibrous connectie tissue, so lots of Energy needed to stretch walls of artery outward; but energy can be stored by stretched elastic gibers and released through elastic recoil Arterioles: NO elastic tissue, just smooth muscle and endothelium; can still contract and relax Capillaries: smallest vessels, site of exchange (so only endothelium), to facilitate exchange; have 1 cell thick enothelium with basal lamina Venules: small vessels; only endothelium, but fibrous tissue, and have a convergent pattern of flow; some smooth muscle begins to appear Veins: more numerous than arteries, have a large diameter, so they are teh VOLUME reservoir; thinner walls than arteries and less elastic tissue, so expand easily when they fill with blood. |
|
|
How do the capillaries of the blood-brain barrier differ from those in the rest of the systemic circulation?
|
Surrounded by pericytes and tight junctions that create a blood-brain barrier
|
|
|
How much of the blood in the circulatory system is found in the veins?
|
more than half
|
|
|
What property of the artery walls plays a key role in the ability of to sustain the driving pressure created by the heart?
|
Stifness of fibrous tissue, and large amounts of elastic tissue and thick muscle tissue
|
|
|
Why does blood pressure decrease as blood flows through the circulatory system?
|
Resistance to flow and also friction
|
|
|
Define systolic and diastolic pressure and give 'average' values.
|
Systolic: highest pressure in aorta, pressure created by left ventricle, 120 mm Hg (systole)
Ventricular diastole: then the pressure in the aorta goes to minimum, 80 mm Hg |
|
|
What is pulse pressure and how do you calculate it?
|
Pulse pressure: measure of strength of the pressure wave, si defined as systolic pressure minus diastolic pressure
Systolic - diastolic pressure |
|
|
How do you calculate mean arterial pressure?
|
Driving pressure (arterial blood pressure, or blood pressure, reflets the drivin pressure for blood flow)
MAP = diastolic P + 1/3 (systolic P - diastolic P) closer to diastolic P because diastole lasts twice as long as systole |
|
|
What kinds of problems might result if blood pressure is too high? Too low?
|
Too low: driving force for blood flow may be too low to overcome gravity; so blood flow and O2 supply to the brain is low, and person may become dizzy and faint
Too high: high pressure may cause weakened areas to rupture and bleed into the tissues, causing hemorrhage and stroke, loss of neurological function, or rapid blood loss into cavity causes blood pressure to fall below the critical minimum |
|
|
Explain how a sphygomanometer measures arterial pressure of the radial artery.
|
Inflatable cuff; when cuff is inflated so that it stops arterial blood flow, no sound can be heard; at that pressure, cuff pressure exceeds arterial pressure, or the systolic pressure
|
|
|
What are Korotkoff sounds?
|
Created by pulsatile blood flow through the compressed artery, so basically the first sound = highest pressure in the artery, or systolic pressure; when they disappear is the lowest pressure in the artery = diastolic pressure
|
|
|
What is the medical term for high blood pressure? You are considered to have high blood pressure if your readings are chronically above what value? Your blood pressure is borderline-high if it is chronically above what value?
|
Hypertensive
140/90: hypertension 120-139 or 80-89: prehypertensive |
|
|
What two main factors determine mean arterial pressure (MAP)?
|
cardiac output x resistance in arterioles
ALSO...total blood volume and distribution of blood in the systemic circulation If blood volume increases, blood pressure increases |
|
|
Which 2 body systems are responsible for homeostatic regulation of blood pressure?
|
CV system
Kidney system (renal) |
|
|
What are the 2 ways the CV system tries to compensate for a decrease in blood volume?
|
Increase cardiac output
Increase resistance (by vasoconstriction) |
|
|
If arterial pressure falls, venous constriction mediated through the (SYMP? PARASYMP) division will have whwat effect on blood distribution and blood pressure?
|
SYMP, increase volume available for the next contraction, so increased stroke volume (cardiac output)
|
|
|
Which vessels are the main site of variable resistance in the systemic circulation?
|
Arterioles
|
|
|
Write the mathematical expression for the relationship between radius and resistance.
|
Resistance is proportional to 1/r^4
|
|
|
What are some chemicals involved in vasoconstriction? Vasodilation?
|
Vasoconstriction: norepinephrine in alpha receptors, or barorecetpor reflex
Vasodilation: Epinephrine, B2 receptors, from adrenal medulla |
|
|
What is myogenic autoregulation? Explain the mechanism by which it occurs.
|
Vascular smooth muscle has the ability to regulate its own state of contraction
Without it, an icnrease in blood pressure actually increases blood flow through an arteriole; but because smooth muscle fibers in the wall of an ateriole stretch because of increased blood pressure, the arteriole constricts...so it increases resistance, decreasing blood flow It works because when smooth muscle cells are stretched, mechanically -gated Ca2+ channels in the muscle membrane open, and result in contraction |
|
|
Tonic norepinephrine + ___ receptors -> myogenic tone
|
alpha
So increase norepi -> vasoconstrict decrease norepi -> dilates |
|
|
Alpha receptors are most sensitive to what neurotransmitter?
|
Norepi
|
|
|
Epinephrine + ___ receptors results in vasodilation
|
B2 receptors (not innervated); think of fight-or-flight; vasodilation once see epinephrine
|
|
|
Why don't all tissues get equal blood flow at all times?
|
B/c different metabolic needs of individual organs, governed by local control mechanisms
|
|
|
At rest, which four organ systems get most blood flow?
|
Brain, Liver, kidneys, and skeletal muscle
|
|
|
Are arterioles arranged in series or parallel?
|
Parallel
|
|
|
At any given moment, the total blood flow through all arterioles =
|
CO
|
|
|
When resistance of an arteriole increases, blood flow through it
|
Decreases
|
|
|
When blood flow decreases through through one set of arterioles, where does that blood go?
|
Blood is diverted from high resistance arterioles to lower-resistance arterioles
|
|
|
In what part of the brain is the neural control center for blood pressure homeostasis found?
|
Medulla oblongata
|
|
|
What are the two main receptors for blood pressure located? What types of sensory receptors are they?
|
2 main receptors:
1) Carotid arteries (pressure of blood flowing to the brain) and aorta (pressure in body) Baroreceptors |
|
|
What is significant about their locations? Are these receptors tonic or phasic?
|
1) Carotid arteries (pressure of blood flowing to the brain) and aorta (pressure in body)
Tonic (fire continuously at normal BP) |
|
|
Match the components of the baroreceptor reflex to the standard steps of a reflex (sensor, afferent path, etc. Fig. 22)
|
LOOK AT FIG.
|
|
|
An increase in sympathetic activity will have what effect on heart rate, force of contraction, arteriolar diameter, and MAP?
|
Heart rate: UP
Force of contraction: UP Arteriolar diameter: DOWN MAP: UP |
|
|
What is orthostatic hypotension? Why does blood pressure initially fall when standing up after lying flat?
|
When you are lying down, blood is distributed evenly, but then when you stand up then the blood is pooled unevenly in the lower extremities. Then, the pooling creates less venous return, and thus cardiac output falls and blood pressure decreases.
|
|
|
Map the reflex response to orthostatic hypotension?
|
Decrease BP -> decrease firing of baroreceptors -> Increase sympa, increase force of contraction, and thus cardiac output, then then increase vasoconstriction, to increase peripheral resistance, and increase heart rate
|
|
|
Explain the relationship between total cross-sectional area and velocity of flow in the circulatory system. Specifically, how does the total cross-sectional area of capillaries compare to that of larger-diameter blood vessels?
|
As it increases, velocity goes down; highest in capillaries
|
|
|
Capillary pores are too small to allow proteins to pass through them. How then do protein hormones and other essential prteins move out of the blood into the interstitial fluid?
|
By transcytosis across the endothelium
Fenestrated capillaries - large pores |
|
|
Define bulk flow.
|
Mass movement of fluid as the result of hydrostatic or osmotic pressure gradients.
|
|
|
What creates the osmotic pressure gradient between the blood and the interstitial fluid?
|
Determined by solute concentration: main solute difference between plasma and interstitial fluid is due to proteins
|
|
|
What is colloid osmotic pressure?
|
Osmotic pressure created by the presence of the proteins; higher in the plasma than in the interstitial fluid; constant throughout the capillary
|
|
|
What forces create filtration and absorption in the capillaries? What determines net flow across capillary walls?
|
Filtration: Hydrostatic change in pressure, or Pcap - Pinterstitial fluid
Absorption: Colloic osmotic pressure, or Pressure in the IF - Pressure in the capillaries Net pressure: hydrostatic change in pressure + colloid osmotic change in pressure Positive: filtration Negative: absorption |
|
|
Name the 3 systems with which the lymphatics interact and explain the role of the lymphatics in each system.
|
CV system, digestive system, immune system
Role of lymphatics: 1) Returning fluid and proteins filtered out of the capillaries to the circulatory system 2) Picking up fat absorbed at the small intestine and transferring it to the CV system 3) Serving as a filter to help capture and destroy foreign pathogens |
|
|
Compare the anatomy of the lymphatic system to the CV system.
|
No single pump
Move interstitial fluid Like close to blood capillaries Thinnest endothelium - thinner than capillaries Larger vessels have semilunar valves, like valves in the venous circulation Empty into venous circulation Depends on wave of contraction of smooth muscle in the walls of the larger lymph vessels Skeletal muscle pumps helps lymph flow |
|
|
Where does lymph rejoin the blood?
|
Just under the collarbones, where the L and R subclavian veins join the internal jugular veins
|
|
|
Name the factors that influence fluid flow through the lymphatics (does lymph system have a pump like the heart?)
|
Factors:
1) Waves of contraction of smooth muscle in walls of larger lymph vessels 2) Contractile fibers in the endothelial ecells 3) 1-way valves 4) External compression created by skeletal muscles |
|
|
What is edema?
|
Immobilized limb frequently swells from accumulation of fluid in the interstitial space
|
