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AU17: Physiology > Cardio Physiology > Flashcards

Cardio Physiology Flashcards

(82 cards)

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1
Q

What is hematocrit?

A

Percent of blood volume that is composed of RBCs

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2
Q

If the plasma is 55% what is the hematocrit?

A

45%

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3
Q

________ carry blood away from the heart. ______ carry blood back to the heart.

A

Arteries; veins

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4
Q

What is the equation for flow?

A

Flow = Change in pressure/resistance

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5
Q

What has the biggest effect on resistance?

A

The radius of the tube.

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6
Q

What happens to resistance with more hematocrit?

A

Higher resistance

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7
Q

What are the three roles of valves?

A
  1. Provide rigidity
  2. Don’t allow back flow
  3. Electrically isolate atria from ventricles
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8
Q

How are muscle cells electrically coupled?

A

Via gap junctions

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9
Q

T/F: Cardiac muscle cells can be recruited.

A

FALSE

Each fiber contracts with each beat

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10
Q

Describe the parasympathetic innervation of the heart.

A

Vagus nerve innervates the ATRIA only. Uses ACETYLCHOLINE to activate muscarinic receptors.

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11
Q

Describe the sympathetic innervation of the heart.

A

Thoracic spinal nerves innervate the ATRIA and VENTRICLES. They release EPINEPHRINE and NOREPINEPHRINE to activate BETA receptors.

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12
Q

_________ innervation controls stroke volume and heart rate while _________ innervation only controls heart rate.

A

Sympathetic; parasympathetic

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13
Q

What is the flow of electric current through the heart?

A

SA node -> AV node -> bundle of HIS -> L and R bundles -> purkinje fibers

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14
Q

How are the nerve branches of the heart backed up in case things stop working?

A

All of the nerve fibers can spontaneously fire if the previous set of nerves don’t fire

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15
Q

What is the only method of communication between the atria and ventricles?

A

AV node

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16
Q

The electric signal goes slowly through which part of the nerve system?

A

From SA through the AV bundle

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17
Q

What is responsible for the rapid depolarization phase of myocardial muscles?

A

Rapid opening of voltage-gated Na channels

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18
Q

What causes the plateau phase of the myocardial ventricular cell contraction?

A

Calcium channels and K channels are open. Ca enters while K slowly leaves the cell.

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19
Q

What causes the repolarization of myocardial cells?

A

K rapidly leaving the cell

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20
Q

T/F: Myocardial ventricular cells have a true resting potential.

A

TRUE

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21
Q

Explain why autorhythmic cardiac nodal cells do not have a true resting potential?

A

Na ions are constantly leaking into the cell through FUNNY CHANNELS

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22
Q

Describe the process of an action potential in a nodal cell.

A

Slow entry of Na followed by slow entry of Ca -> threshold -> Ca rapidly enters (depolarization) -> K channels open and Ca close (repolarization)

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23
Q

T/F: Cells of the SA node have less funny channels than cells in the AV node.

A

FALSE

Less funny channels further down the cascade

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24
Q

What do P, QRS, and T waves represent?

A 
P = atrial depolarization
QRS = ventricular depolarization
T = ventricular repolarization
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25
How does the electrical signal trigger muscle contraction?
Calcium channels open -> trigger calcium enters -> calcium induced calcium release -> contraction
26
Why do cardiac muscle cells have a long refractory period?
To allow for the ventricles to fill
27
What is the first heart sound?
Closure of AV valves
28
What is the second heart sound?
Closure of aortic and pulmonary valves
29
_________ is the narrowing of the valves. ________ is when the valves are insufficient.
Stenosis; regurgitation
30
Systemic and pulmonary circulations are in __________. Organs in systemic circulation are in __________.
Series; parallel
31
What causes the aortic valve to open?
Pressure in ventricle > pressure in aorta
32
When the heart is in diastole, the ventricles are _________.
Relaxed
33
Describe the process of the heart from diastole through systole.
1. Passive filling 2. SA node -> atrial kick 3. Ventricles begin to contract 4. Isovolumic contraction: both valves closed 5. Ventricular pressure becomes greater than aortic pressure and aortic valve opens 6. Ejection and repolarization
34
T/F: The left heart creates more pressure than the right heart.
TRUE
35
What is cardiac output?
The volume of blood each ventricle pumps per minute
36
What is the equation for Cardiac output?
CO = heart rate x stroke volume
37
T/F: Parasympathetics speed up the heart rate.
FALSE Slow down
38
What are the two ways to increase stroke volume?
1. Increase Preload/End diastolic volume: volume of blood in ventricles 2. Increase sympathetic input
39
What is the Frank-Starling mechanism?
The fuller the ventricles are the harder they will contract due to stretch-tension
40
T/F: Increased sympathetics cause a more rapid contraction AND relaxation of myocardial cells.
True
41
How do increased sympathetics ultimately cause greater cardiac output?
Increase Ca
42
Is it possible to increase just one of the two possible determinants of cardiac output?
No. Increasing one will increase the other
43
Which vessels are adjusted to regulate blood pressure?
Arterioles
44
Does blood push through the arteries in a pulsating fashion with each heartbeat?
No! At systole it stretches the arteries and the recoil continues to push during diastole
45
What determines organ blood flow?
MAP
46
How is the intrinsic tone of arterioles controlled?
Local controls: active hyperemia and flow autoregulation Extrinsic: Sympathetics
47
Sympathetic stimulation of _____________ receptors causes vasoconstriction to decrease blood flow. While _____________ receptors leads to vasodilation to cause an increase in blood flow.
Alpha-adrenergic; beta-adrenergic
48
What are some vasodilators?
1. No | 2. PGI2
49
What is a vasoconstrictor?
Endothelin-1
50
Increased capillary hydrostatic pressure and increased interstitial protein concentration will both lead to __________.
Filtration
51
Increased interstitial hydrostatic pressure and increased protein concentration in the plasma will lead to __________.
Absorption
52
At rest approx _____ of the total blood volume is in the veins.
60%
53
Alterations in venous return can alter __________, which can in turn increase stroke volume and cardiac output.
EDV
54
Among all blood cells, only the _________ are true cells with nuclei.
Leukocytes
55
What is the major breakdown product of hemoglobin?
Bilirubin
56
When an RBC is destroyed, the iron is bound by __________ and delivered to bone marrow.
Transferrin
57
What happens when the kidneys sense low O2 levels?
Kidneys produce and secrete more erythropoietin -> production of RBCs in bone marrow -> more O2 carrying capacity
58
Clotting can occur in the absence of all cellular elements except __________.
Platelets
59
Factors II, VII, IX and X are all __________ proteins.
Coagulation
60
Proteins C and S are __________ proteins.
Anticoagulation
61
Protein C, TFPI, and Antithrombin III all function to ________ clot formation.
Limit
62
_________ mediates the process of dissolving fibrin clots.
Plasmin
63
What is the best way to get more blood flow to a specific organ?
The arteries leading to the organ will decrease their resistance
64
What constitutes the change in pressure through most capillary beds and in the organs?
MAP - VP
65
What is the equation for MAP?
MAP = cardiac output x total peripheral resistance
66
What determines organ blood flow?
MAP
67
Decrease in blood volume will lead to a drop in _______.
MAP
68
What two factors can the body increase if there is a drop in MAP?
TPR or CO
69
What neurons function as sensors in the homeostatic maintenance of MAP?
Baroreceptors
70
Where are baroreceptors located?
Aortic arch and carotid sinuses
71
What will cause baroreceptors to fire more frequently?
An increase in MAP
72
What is the result of baroreceptors firing?
Decreased sympathetic outflow to hear Increased parasympathetic outflow to heart Reduced CO
73
T/F: Baroreceptors cause an autonomic response that has all its effect in the heart.
FALSE Also effects arterioles and veins
74
Describe the events that will lead to a stabilization of MAP after a hemorrhage.
Sympathetics increase to the heart, arterioles and veins Heart: heart rate and stroke volume increase Veins: veins constrict -> higher venous pressure and venous return -> higher EDV -> increase stroke volume Arterioles: constrict leading to increased TPR
75
Describe what happens to blood volume when MAP increases.
Squeezes more fluid out of blood and into the urine -> reduction in blood volume -> decrease in MAP
76
During a hemorrhage, which factors instantly increase?
Heart rate and TPR The rest drop abruptly before increasing
77
At capillaries, reduced MAP increases ___________ and reduces ____________ to help protect blood volume.
Absorption; filtration
78
Does plasma volume or erythrocyte volume have a more exaggerated recovery 18 hours after a hemorrhage?
Plasma volume
79
During exercise, what happens to resistance in skeletal muscles?
Decreases due to vasodilation
80
What factor determines maximal oxygen consumption?
Cardiac output
81
What is the difference between diastolic and systolic dysfunction in heart failure?
Diastolic: reduced ventricular compliance -> lower EDV -> decreased stroke volume Systolic: decrease in cardiac contractility -> lower stroke volume at any EDV
82
What is the Frank-Starling mechanism?
The heart will pump harder if its filled with more blood. To increase stroke volume increase venous return

AU17: Physiology (12 decks)

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