Lecture 7 Flashcards
(127 cards)
1
Q
Blood is oxygenated in which circulation?
A
Pulmonary circulation
2
Q
Blood is delivered to end tissues in _____________ circulation
A
systemic
3
Q
What does “vasculature is parallel” mean? (2 things)
A
1) No “leftover” blood from one organ being delivered to another
2) Same composition of blood being delivered
4
Q
Blood is constantly “_______________” to maintain consistent composition
A
reconditioned
5
Q
What do organs that recondition blood receive?
A
Much more blood flow than what is necessary for their own metabolic needs
6
Q
1) Reconditioning organs receive excess what?
2) What ability does this confer them?
A
1) Reconditioning organs receive excess blood
2) Improved ability to withstand temporary reductions in blood flow
7
Q
True or false: if an organ is not a reconditioning organ, all the blood it receives is solely for its needs
A
True
8
Q
1) Can the amount of blood flow to an organ be changed? If not, explain. If so, give an example
2) Are non-reconditioning organs more or less susceptible to damage than reconditioning ones?
A
1) Can be adjusted (skeletal muscle during exercise)
2) More susceptible to damage
9
Q
Brain suffers irreparable damage after only _________________ without O2
A
4 minutes
10
Q
1) Flow rate of blood is ____________ proportional to pressure gradient
2) Greater difference in pressure = _____________ flow rate
A
1) Directly
2) Increased
11
Q
1) Flow rate of blood is ________________ proportional to vascular resistance
2) Greater vascular resistance = ______________ flow rate
A
inversely; decreased
12
Q
What is the formula for flow rate?
A
Difference in pressure gradient / resistance of blood vessel
13
Q
Blood flows ____[up/down]______ a gradient (from _______ pressure to ______ pressure)
A
down; high to low
14
Q
What causes resistence?
A
Friction of blood moving against vascular walls
15
Q
Resistance is:
1) __________ proportional to viscosity
2) __________ proportional to vessel length
3) __________ proportional to vessel radius (most important)
A
1) Directly
2) Directly
3) Inversely
16
Q
What is the most important part of resistance?
A
Inversely proportional to vessel radius
17
Q
Are systemic and pulmonary circulations open or closed loops? Where do they begin and end?
A
Closed vascular loops that begin and end with the heart
18
Q
Describe the branching organization of the body’s vasculature
A
1) Arteries/veins
2) Arterioles/venules
3) Capillaries (exchange occurs here)
19
Q
True or false: Different vessels have different specializations
A
True
20
Q
1) Describe the size of arteries and their resistance and pressure
2) What kind of paths are arteries?
3) What do they act as?
4) What do they provide while the heart is relaxed?
A
1) Large radius, little resistance, preserves pressure
2) Rapid-transit paths between heart and organs
3) A pressure reservoir
4) Provides driving force when heart is relaxing
21
Q
What type of vessel’s walls have elastic recoil?
A
Arteries
22
Q
True or false: All vessels have endothelial lining that is continuous with the heart’s endothelium
A
True
23
Q
What two things surround arterial endothelium?
A
Smooth muscle and connective tissue
24
Q
What two things make up the connective tissue that surrounds arterial endothelium? What property does each confer?
A
1) Collagen: tensile strength against high pressure
2) Elastin: elasticity
25
Where do arteries have more elastin?
Near the heart
26
1) Define blood pressure
2) What does it depend on?
1) Force exerted by blood against vessel walls
2) Volume of blood and compliance of walls (how easily they can stretch)
27
True or false: Arterial pressure fluctuates between systole and diastole
True
28
1) What happens during systole?
2) What happens during diastole?
1) Stroke volume of blood enters
2) No blood enters, stored blood leaves during elastic recoil
29
Define systolic pressure
Maximum pressure exerted (when blood is injected during systole)
30
Define diastolic pressure
Minimum pressure exerted (when blood is draining off)
31
What pressure is 0mmHg during diastole? Which doesn't fall to 0?
Ventricular pressure is 0, arterial pressure does not fall to 0
32
When you palpate a pulse, what are you feeling?
An artery expand during systole
33
1) What is pulse pressure?
2) Give an example
1) Difference between systolic and diastolic pressures
2) BP: 120/80. Pulse pressure: 40.
34
1) What is a sphygmomanometer?
2) What happens during blood pressure being taken?
1) Blood pressure cuff
2) Air pressure in cuff transmitted to underlying vessel (brachial artery)
35
What does it mean if cuff pressure > vessel pressure?
Vessel occluded; no pulse
36
What does it mean if vessel pressure > cuff pressure?
Vessel not occluded; pulse detectable
37
Under what two conditions is there no sound during a blood pressure reading?
1) Vessel completely occluded (no blood flow)
2) Vessel completely patent (laminar flow)
38
When is sound detected during BP reading? What is this called?
Turbulent blood flow (vibrations through stethoscope); Korotkoff sounds
39
1) How far do you inflate a BP cuff?
2) List the next step
3) List the step after that
1) Until vessel is occluded
2) Pressure released until it falls just below systolic pressure (first sound is systolic bp)
3) Pressure falls below diastolic pressure (second sound is diastolic)
40
Describe what should be occurring when BP cuff pressure is released until it falls just below systolic pressure
1) First sound heard = systolic pressure
2) Cuff pressure still greater than diastolic pressure; artery is still occluded during diastole
41
Describe what should be occurring when BP cuff pressure falls below diastolic pressure
1) Vessel is patent, laminar flow returns, no sounds
2) Last sound heard= diastolic pressure
42
What is Mean Arterial Pressure (MAP)?
Average blood pressure throughout cardiac cycle
43
1) What is pulse pressure?
2) What is MAP?
3) What would MAP be if BP was 120/80?
1) SP-DP
2) Diastolic pressure + 1/3rd pulse pressure
120/80
3) 80 + (1/3) 40 = 93 mm Hg
44
1) Define MAP
2) What does MAP average?
1) The perfusion pressure seen by organs in the body
2) 65 -100; usually around 70 needed to comfortably sustain organs
45
Even 1 minute at a MAP of _____ or lower can result in organ complications bc the organ is not receiving enough oxygen
50
46
1) What are the major resistance vessels?
2) Why do they have resistance?
3) What does this do?
1) Arterioles
2) Radius is small enough to offer considerable resistance
3) Drives the pressure differential
47
1) Where can radius be adjusted?
2) What does this do?
1) The radius (and therefore the resistance) of arterioles can be adjusted
2) Regulate blood pressure
48
What part of arterioles allows for vasoconstriction and vasodilation? What does this do?
Smooth muscle; allows for adjusting radius (resistance)
49
What is a difference between arteries and arterioles?
Arterioles have little elastic tissue, instead they have smooth muscle that is richly innervated by sympathetic fibers
50
1) What is arteriole smooth muscle sensitive to?
2) Where is it around the arteriole?
1) Smooth muscle also sensitive to circulating hormones
2) Runs circularly around arteriole
51
What is vascular tone?
State of partial/baseline constriction; baseline arteriolar resistance
52
List and describe the two factors responsible for vascular tone
1) Surface membrane voltage-gated Ca+ channels
-Allows self-induced contraction without neural/hormonal input
2) Sympathetic fibers supplying arterioles constantly release NE
-Baseline constriction
53
List the 2 causes for arteriolar constriction/dilation, and what each does
1) Local (intrinsic) controls: Determine distribution of cardiac output
2) Extrinsic controls: Blood pressure regulation
54
1) Fraction of total CO delivered to each organ varies depending on what?
2) _________ pressure to the organs is the same, the __________ vary in their radii and different organs have varying degrees of arteriole vascularization
1) Tissue demands
2) Arterial; arterioles
55
1) More blood flows to areas of ______ resistance than ___________ resistance
2) Skeletal muscle arterioles being dilated during exercise does what to resistance and blood flow?
1) lower; higher
2) Lower resistance, causing preferential blood flow
56
True or false: Brain’s total blood supply remains constant no matter the activity with no change in regional flow in brain areas
False; regional flow in brain areas can vary
57
1) What do intrinsic controls do?
2) What two categories influence these controls? Give examples of each
1) Intrinsic controls adjust blood flow through an organ by affecting arteriole smooth muscle
2)
-Chemical influences: metabolic changes, histamine release
-Physical influences: stretch, stress, temperature
58
1) Where are metabolic chemical influences especially important?
2) What does this cause in these locations?
1) Heart, skeletal muscle, brain, and organs with variable metabolic needs
2) Local concentration change [in metabolic chemicals] triggers vasodilation and hyperemia (increased blood flow)
59
Give examples of triggers for [chemical] metabolic influences on intrinsic control
1) Decreased O2
2) Increased CO2, increased acid (carbonic acid from CO2, lactic acid from glycolysis)
3) Increased K+ (repeated AP’s outpace Na/K pump’s ability to restore ion gradients)
4) Increased osmolarity (solutes increased during elevated metabolism)
5) Adenosine release (especially in cardiac muscle)
60
1) Give an example of a chemical metabolic influence on intrinsic control
2) When are they released?
1) Endothelial vasoactive paracrines (locally acting chemicals)
2) In response to metabolic changes
61
1) What are endothelial vasoactive paracrines (locally acting chemicals) a type of?
2) What is the best known example? What does it do?
3) Give another example
1) Chemical metabolic influence on intrinsic control
2) Best known: nitric oxide
-Local arteriolar vasodilation (smooth muscle relaxation)
-Many other roles in the body
3) Endothelin: potent vasoconstrictor
62
1) Give another example of chemical metabolic influence on intrinsic control besides endothelial vasoactive paracrines. Define it
2) What happens to metabolic activity while blood is blocked?
3) What happens to waste products? What does this trigger?
1) Reactive hyperemia: Local blood supply is cut off (injury, applying tourniquet)
2) Metabolic activity continues as blood is blocked
3) Waste products accumulate, not “washed” away due to lack of blood; triggers dilation
63
What happens when blood flow resumes (tourniquet removed) in reactive hyperemia?
Blood flow is higher due to dilated arterioles
64
In addition to metabolic influence, chemically mediated intrinsic control can be mediated through ____________ release
histamine
65
1) What is histamine and what triggers its release?
2) What does histamine do? What does this cause?
1) Paracrine stored in connective tissue and in circulating WBCs; tissue injury or allergic reactions trigger histamine release
2) Acts locally to relax arteriolar smooth muscle (vasodilation); redness, swelling
66
Name 3 physical influences on intrinsic control
1) Stretch
2) Stress
3) Temperature
67
1) Smooth muscle of arterioles responds to stretching how? Why?
2) How does it respond to reduced stretch?
3) What is the purpose of these responses?
4) Give an example of arteriole smooth muscle response
1) Increasing tone via vasoconstriction; mechanism to resist the initial stretch
2) With vasodilation
3) Maintain normal blood flow to tissue
4) Hemorrhage, MAP falls, blood flow to an organ decreases, arteriole stretch decreases, arterioles dilate, blood flow increases to attempt to meet organ demands
68
1) Describe shear stress
2) How does an arteriole respond to shear stress? What does this do?
1) Longitudinal force over endothelial cells as blood flows over it
2) Causes endothelial cells to release nitric oxide, promoting vasodilation; reduces shear stress
69
1) What does heat do to arterioles? Why is this useful?
2) What does cold do to arterioles? Why is this useful?
1) Vasodilation, useful for promoting blood flow to an area
-Increases blood flow to help heal damaged tissue, stimulates skins sensation which blocks pain
2) Vasoconstriction, useful for reducing blood flow to an area
-Decreases swelling, counters histamine-induced vasodilation
70
1) What is the most important part of neural control of arterioles? What do they do and what affect does this have on the body?
2) What is released? From what structure? Where does it bind to and where is it found in the body?
1) Sympathetic; promote vasoconstriction. They adjust total peripheral resistance in the body, thereby controlling MAP.
2) NE released from sympathetic nerve endings bind to A1-adrenergic receptors on smooth muscle
-All arteriole smooth walls except cerebral arterioles
71
1) What muscles have powerful local vasodilation mechanisms that allow them to overpower generalized sympathetic vasoconstriction?
2) Why?
1) Skeletal and cardiac
2) Makes more blood available while engaged in "sympathetic" type activity like exercise
72
Give 2 examples of extrinsic control of arterioles
1) Neural control
2) Hormonal Control
73
1) What is the main region of hormonal control over arterioles?
2) What does it do?
1) Cardiovascular control center in medulla of brain stem
2) Integration center for blood pressure regulation
74
How does the adrenal medulla exert hormonal (extrinsic) control over arterioles?
Secretes epinephrine/norepinephrine:
-NE combines with A1 receptors for vasoconstriction, E binds to B2 and A1 receptors; B2 receptors promote vasodilation
75
1) What hormone does the hypothalamus secrete to (extrinsically) control arterioles?
2) What does this do?
1) Vasopressin
2) Regulates water retention of kidneys, affecting water balance
76
1) What hormone does the kidneys secrete to (extrinsically) control arterioles?
2) What does this hormone do?
1) Angiotensin II
2) Regulates salt balance as part of renin-angiotensin-aldosterone system
77
List 3 structures that exert hormonal control over arterioles
1) Adrenal medulla
2) Kidneys
3) Hypothalamus
78
1) What are capillaries?
2) What do cells exchange materials with? What determines this exchange?
1) The exchange site between blood and tissue
-since exchange between blood and tissue cells is not made directly
2) Interstitial fluid; plasma membranes
79
Capillaries slide 33
1) Exchange between interstitial fluid and capillary wall is largely _____[passive/ active]_____
2) Compare the composition of IF and incoming blood
3) What does this mean?
1) Passive
2) Other than large proteins it's essentially the same
3) Assume IF involvement when it comes to exchange between tissues and blood
80
1) Describe the locations of capillaries
2) What are capillaries lacking? What is the exception?
3) How are materials exchanged across capillary walls?
1) Extensive branching, essentially reach every cell
2) Carrier-mediated systems (except in brain capillaries)
3) Diffusion
81
What are the 3 factors that make capillaries ideal for diffusion?
1) Diffusion distance is minimal: capillary walls are extremely thin (1um, hair is 100um), capillary vessels are very narrow (RBCs squeeze through in single file), and barely any cell is farther than 0.1mm from a capillary.
2) Capillaries are distributed in large numbers (billions), tremendous surface area for exchange
3) Blood flows slowly in capillaries
82
1) Define flow rate [of capillaries]
2) Define velocity of flow [of capillaries]
1) Volume of blood per unit of time flowing through given circulatory segment
2) Speed with which blood flows through given circulatory segment
83
True or false: Capillary permeability varies from organ to organ
True
84
List capillary permeability throughout the body from tightest to leakiest
1) Brain: tight junctions prevent transcapillary passage
2) Skeletal muscle, lung tissue: small water-soluble substances can pass through water filled pores. Ions, glucose, amino acids
3) Kidneys, intestines: larger "holes" called fenestrations in the endothelial cells
4) Liver cells: Large gaps (discontinuous capillary endothelial cells); allows large proteins through.
85
1) What can pass through capillaries in skeletal muscle and lung tissue? How do they pass through?
2) What can't pass through?
3) What substances need to find an alternate route through?
1) Small water-soluble substances can pass through water filled pores. Ions, glucose, amino acids.
2) Large materials like proteins
3) Lipid soluble materials like O2/CO2 pass through lipid membrane
86
1) Describe the permeability of the capillaries of the kidneys and intestines
2) What is this important for?
1) Larger "holes" called fenestrations in the endothelial cells
2) Rapidly moving fluid or for absorbing a digested meal
87
1) Describe the permeability of the capillaries of the liver cells?
2) What does this allow for, and why is this important?
1) Discontinuous capillary endothelial cells; large gaps
2) Large proteins to pass through; important because liver synthesizes plasma proteins.
88
True or false: usually slightly less fluid is filtered from the capillaries into the interstitial fluid than what is reabsorbed into plasma
False; slightly more fluid
89
1) What are lymphatic vessels? What form valves?
2) What do they do?
3) What is the difference between interstitial fluid and lymph?
1) One-way vessels that permeate almost every tissue of the body; Overlapping cells form valves
2) Return the remaining interstitial fluid to the blood
3) Interstitial fluid that enters a lymphatic vessel is then called lymph
90
1) Where do lymph vessels empty?
2) What drives this movement of lymph?
3) What else helps this movement?
1) Into venous system near blood entering right atrium
2) "Lymph pump"; smooth muscle of lymph vessels becomes distended with lymph and forcefully contracts
3) Lymph vessels lie between skeletal muscles, which squeeze out lymph when they contract
91
List the 3 purposes of lymph
1) Return interstitial fluid and protein to circulation
2) Immune defense: lymph passes through nodes that contain phagocytes.
3) Helps transport digested fat
92
Define edema
Excess interstitial fluid accumulation
93
List the 4 categories of causes of edema
1) Reduced concentration of plasma proteins.
2) Abnormally increased capillary wall permeability.
3) Increased venous pressure.
4) Unable to return IF to circulation.
94
1) What do capillaries drain into? Describe these.
2) What do venules converge into?
3) Describe the composition of veins
1) Venules; have little tone and resistance
2) Veins
3) Veins have a large radius and offer little resistance. Have thinner walls and less smooth muscle.
95
1) What do veins act as? Are they stretchable or elastic? Do they easily distend?
2) Is blood stagnant in veins?
3) Why is this blood important?
1) Act as blood reservoir. Highly stretchable with little elastic recoil. Easily distend with minimal increase in venous pressure.
2) Not stagnant, just moving slower
3) When needed (like with exercises), the body can use this "extra" blood
96
1) Define venous return
2) By the time blood enters venous system, pressure drops to around _____ mmHg
1) Volume of blood per minute entering each atrium from the veins
2) 17mmHg
97
What are the 5 additional driving factors of venous return?
1) Sympathetic vasoconstriction
2) Skeletal muscle pump
3) Venous valves
4) Respiratory pump
5) Cardiac suction
98
1) Describe sympathetic vasoconstriction of veins. What does this do to EDV and CO?
2) What is the difference between the functions of arteriole constriction and venous vasoconstriction?
1) Veins are not very muscular and have inherent tone, but sympathetic vasoconstriction can produce modest elevation in pressure.
-EDV and therefore CO are increased.
2) In arterioles, constriction reduces blood flow; in veins, constriction helps squeeze out the "stored" blood
99
1) Many veins lie between ________________, the pumping of which squeezes venous blood along the vessels.
2) This helps to counteract effect of _____________
1) Skeletal muscles, the pumping of which squeezes venous blood along the vessels.
2) gravity
100
1) What vessels are most affected by gravity? Why?
2) Where does blood pool? Why?
3) How many compensatory mechanisms counter gravity?
1) Vessels below heart level are subject to pressure from weight of the overlying column of blood
2) Arteries subject to same force, but are not nearly as distensible, so blood pools in lower extremity veins instead
3) Two
101
List the 2 compensatory mechanisms to counter gravity
1) Fall in MAP when standing up triggers sympathetic venous vasoconstriction (which drives blood forward)
2) Contractions in skeletal muscle interrupt the column of blood, so that a given portion of a vein is not subject to the weight of the entire venous column
102
True or false: Despite reflexes aimed at maintaining MAP, eventually blood flow to brain is reduced
True
103
1) Where are venous valves? What do they do?
2) What occurs when venous valves become incompetent?
1) One-way valves at 2-4cm intervals that keep blood from backflowing into tissues
2) Varicose veins
104
1) What is the pressure in the chest cavity? Why?
2) Explain the respiratory pump
1) Due to respiration, pressure in chest cavity is slightly less than atmospheric pressure
2) Veins in lower extremities are subject to normal atmospheric pressure; pressure gradient promotes increased venous return
105
Explain cardiac suction
Atrial pressure is below 0 mmHg during ventricular contraction (suction force) which exerts a vein-to-atria-to-ventricle pressure gradient, further enhancing venous return
106
___________ is the main driving force for propelling blood to the tissues, and there are many mechanisms involved in regulating this
MAP
107
Pressure must be carefully regulated; why does it need to remain within certain limits?
Needs to be high enough to drive pressure, but not so high that heart and vessels do extra work
108
How do you describe MAP?
MAP = CO X TPR (total peripheral resistance)
**This is describing the factors behind what MAP means, not how it is calculated**
109
How do you calculate MAP?
MAP = diastolic pressure + 1/3rd pulse pressure
110
List all the factors affecting CO and TPR
1) CO depends on heart rate and stroke volume
2) Heart rate depends on balance of sympathetic and parasympathetic activity
3) Stroke volume is affected by sympathetic activity
4) Stroke volume increases with increased venous return (Frank-Starling Mechanism)
5) Venous return is enhanced by the 5 factors we just went over
6) Blood volume determines how much blood is pumped by the heart and is affected by balance between plasma and IF, salt and water balance, and hormones
7) TPR depends on the radii of all arterioles and blood viscosity
8) RBCs affect blood viscosity
9) Arteriolar radius is intrinsically and extrinsically controlled
111
1) CO depends on what two things?
2) Heart rate depends on balance of _______________ and ______________ activity
3) Stroke volume is affected by what?
1) Heart rate and stroke volume
2) sympathetic; parasympathetic
3) sympathetic activity
112
1) What is the Frank-Starling Mechanism?
2) Venous return is enhanced by what?
3) What does blood volume determine? What affects blood volume?
1) Stroke volume increases with increased venous return
2) The 5 factors (symp. vasoconstriction, skeletal muscle pump, venous valves, respiratory pump, cardiac suction)
3) How much blood is pumped by the heart; affected by balance between plasma and IF, salt and water balance, and hormones
113
1) What 2 things does TPR (total peripheral resistance) depend on?
2) What affects blood viscosity?
3) Arteriolar radius is ______________ and _______________ controlled
1) The radii of all arterioles and blood viscosity
2) RBCs
3) Intrinsically and extrinsically
114
1) What monitors MAP?
2) What do they do when deviations are detected?
1) Baroreceptors (pressure sensors) in the circulatory system
2) Reflex responses are initiated to return MAP to set value (short term and long term adjustments)
115
After baroreceptors sense deviations, what happens?
1) Short-term adjustments made in CO and TPR
-Ex: baroreceptor reflex
2) Long-term control adjusts blood volume by adjusting salt and water balance via urine output and thirst
116
Baroreceptor reflex:
1) What are baroreceptors that are mechanoreceptors that detect changes in MAP?
2) What are they constantly doing? When does this increase?
3) What alters sympathetic/parasympathetic balance in effector organs?
1) Carotid sinus and aortic arch
2) Firing AP's, which increase in frequency with rising MAP
3) Cardiovascular control center in medulla of brainstem
117
1) What can influence respiratory activity?
2) What regulate salt/water balance?
1) Carotid and aortic artery chemoreceptors sensitive to O2 and CO2
2) Left atrial volume receptors and hypothalamic osmoreceptors
118
What governs cardiovascular responses associated with certain emotions and behaviors like blushing, anger, fear?
Cerebral cortex-hypothalamic pathway
119
What part of the circulatory system helps regulate temperature?
Hypothalamic control over cutaneous arteries
120
1) A definite cause for HTN is only identified in ____% of cases
2) What is secondary HTN?
1) 10% of cases
2) HTN due to other problems (like kidney disease)
121
1) Primary HTN (90% of cases) has ___________________ cause
2) Factors affecting HTN include what?
1) Unknown underlying cause
2) Genetics, obesity, stress, diet, smoking, alcohol
122
1) HTN is self-perpetuating; explain this.
2) Why can't baroreceptors help?
1) Constant HTN damages vessels, predisposing to atherosclerosis, which narrows lumens, which increases TPR, which further elevates BP
2) They adapt to chronically elevated BP as their new baseline
123
List 6 complications of HTN
1) Left ventricular hypertrophy as heart works harder to pump blood against resistance
2) Systolic heart failure as heart weakens and unable to pump against elevated pressure
3) Strokes caused by rupture of cerebral arteries
4) Heart attacks caused by rupture of coronary arteries
5) Kidney failure from damaged renal vessels
6) Vision loss from retinal vessel damage
124
Define hypotension. What can cause it?
1) Low blood pressure
2) Low volume or weak pump
125
Define circulatory shock and why it must be reversed
1) When blood pressure falls so low that tissue demands are not met
2) To prevent organ damage and death
126
Name and describe the 4 types of circulatory shock
1) Hypovolemic shock: Extensive blood volume loss
2) Cardiogenic shock: Failure of weakened heart to pump blood
3) Vasogenic shock: Widespread vasodilation triggered by substances (extensive histamine from severe rxn)
4) Neurogenic shock: Neurally defective vasoconstrictor tone
127
What type of shock may occur during an anaphylactic allergic reaction?
Vasogenic shock
