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Physiology Quiz 6 (Cardiovascular) Flashcards

0
Q

Ectopic center

A

Area of cardiac muscle which normally does not perform pacemaker function that suddenly takes up pacemaker function
Common source of arrhythmia

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1
Q

Automaticity

A

Ability to fire action potential with no outside influence acting upon it (all heart structures have this property)

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2
Q

Causes of ectopic center

A
  • Localized ionic imbalance
  • high level of vagal tone to heart
  • ischemia to area of the heart
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3
Q

Vasovagal response

A

Sudden increase in parasympathetic tone to heart (Ach), often caused by sudden, intense emotional shock; causes syncope

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4
Q

Ischemia

A

Decreased blood flow

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5
Q

Hypoxia

A

Decreased oxygen

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6
Q

How Ach acts on heart

A

Decreases HR

Decreases inotropic state

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7
Q

Hemodynamics

A

Application of physics to blood flow in the cardiovascular system

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8
Q

Equation for blood flow to an area

A

Q=P/R
Q= flow
P= pressure (mmHg)
R= resistance to blood flow

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9
Q

Resistance to blood flow equation

A

R= 8(nu)(length of pathway)/pi(radius to the 4th power)

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10
Q

Poiseuille’s law

A

Q=P(radius to 4th power)(Pi)/8(nu)L

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11
Q

Pascals law

A

Relates the effects of gravity on perfusion of blood to regions as well as development of edema

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12
Q

Starling-landis relationship

A

(Graph with hydrostatic pressure and oncotic pressure lines criss-crossing)
Relates oncotic and hydrostatic pressures along capillary length

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13
Q

Hydrostatic pressure drops the entire length due to…

A

Resistance to flow in capillary

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14
Q

Cause of current sink

A

Area becomes hypoxic
Charge approaches 0
-not producing ATP
-decreased energy for sodium potassium pump
-sodium leaks in and pump does not pump potassium out, so charge becomes more positive
Becomes current sink

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15
Q

What happens when a current sink forms?

A

Will start initiating spikes

Becomes new pacemaker

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16
Q

Does a current sink give a coordinated contraction ?

A

No

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17
Q

What pathology can cause a current sink

A

Atherosclerosis

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18
Q

Atrial flutter

A

Faster than normal contraction of atria; regular pattern

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19
Q

Atrial fibrillation

A

Aria beat irregularly and out of coordination with ventricles

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20
Q

Examples of abnormal centers of pacemaker functions

A

Atrial fibrillation
Atrial flutter
Paroxysmal ventricular tachycardia

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21
Q

What typically proceeds paroxysmal ventricular tachycardia?

A

Premature ventricular contraction

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22
Q

Paroxysmal ventricular tachycardia

A

a rapid heartbeat of sudden onset and termination caused by a quick succession of discharges from an ectopic site in a ventricle

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23
Q

What happens with ventricular fibrillation

A

Mass, uncoordinated contraction of ventricle; no blood pumped to system
Typically fatal in about 5 min

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24
Re-entry phenomenon
Causes impulse in a cardiac contractile cell to go back up toward SA node and cancels out impulse; causes SA node to lose influence
25
What must you have for re-entry phenomenon to occur
Slowed conduction | Unilateral block
26
Oncotic pressure
Osmotic pressure of blood due to plasma proteins
27
Hydrostatic pressure
Pressure within blood vessel due to pumping of heart
28
Where hydrostatic pressure is greater than oncotic pressure, where will fluid flow?
Capillary--> tissue
29
Where oncotic pressure is greater than hydrostatic, where will fluid flow?
Tissue--> capillary
30
Edema
Change in relative levels of pressure in system that cause net gain of fluid in tissue
31
What increases edema
Increased hydrostatic pressure (standing, pregnancy, renal disease, congestive heart failure) Decreased oncotic pressure(starvation, liver dysfunction) Increased blood volume
32
What will shift the hydrostatic line upward
Congestive heart failure Renal disease Pregnancy
33
What will shift the oncotic pressure line downward?
Chronic starvation | Liver dysfunction
34
How much atrial pressure provides adequate perfusion for brain?
80-100 mmHg
35
Venous return
Blood returned to heart
36
Venous system is responsible for
Returning blood to heart
37
Qualities of venous system that help maintain venous return
Skeletal muscle pump Venous valves Thoracoabdominal pump
38
Skeletal muscle pump
Mechanism by which blood is forced back toward the heart when skeletal muscle contracts
39
Venous valves
One way valves that permit flow only in one direction
40
Vericose veins
When valves are damaged, blood is allowed to flow back to muscle -happens in pregnancy Eg. Hemoroids
41
Toracoabdominal pump
Blood is pulled to the heart by negative pressure in chest caused by breathing Positive pressure in abdomen pushes blood toward thoracic cavity -most influential during exercise
42
Factors to consider for how BP in CV system is regulated/influenced
Cardiac output Total peripheral resistance (diameter) Distensibility of vessels- influences, but will not control BP Viscosity of blood-influences, but will not control BP Blood volume available
43
Factors that act rapidly
Cardiac output | Total peripheral resistance
44
Factors that are slow acting
Changes in blood volume
45
Cardiac output
Amount of blood propelled by heart into systemic circulation per minute
46
Total peripheral resistance
Resistance to blood flow into systemic circulation
47
Blood volume
Total volume of blood in cardiovascular system
48
What are blood volume changes mediated by
Hormones
49
What % of body weight is blood?
6% | Better conditioned athletes, pregnancy ^ BV
50
Cardiac output and total peripheral resistance are changed by altering...
Neural activity
51
Cardiac output equation
CO=SV x HR SV= stroke volume
52
Stroke volume
mL of blood propelled with each ventricular contraction (dependent on body size)
53
Ejection fraction
% of total volume in ventricle that is expelled in one beat (Usually 60-67% @ rest) Increases with exercise due to increased inotropic force
54
Increased papasympathetic tone to heart causes...
Decreased HR | Decreased inotropic state
55
Increased sympathetic tone to heart causes...
Increased HR | Increased inotropic state
56
Autonomic influence on the heart is determined by
Hypothalamus
57
Arterial pressure equation
AP= CO x TPR | Want to act upon TPR to change AP; mostly controlled by radius of vessels
58
Total peripheral resistance is under exclusive control of what autonomic system?
Sympathetic
59
Control of TPR occurs primarily at the level of the_____ and is mediated by ______
Arteriole; vascular smooth muscle
60
Only places arteriolar vascular smooth muscle is innervated by parasympathetics are
Salivary glands | External genitalia
61
Local control of TPR is exerted by
Metabolic byproducts | K, H, lactic acid
62
Intrinsic control predominates over these systems
Muscle | Heart
63
Extrinsic control predominates over these systems
GI Skin Kidneys
64
Blood flow received by an area is a result of what system?
Balance between local and extrinsic control
65
Local/intrinsic control
Metabolic byproducts
66
Extrinsic control
Autonomic nervous system
67
When is skin a priority for circulation
In hot weather (because it is a thermoregulator)
68
How much cardiac output does the average person have at est
5-6 L/min
69
What type of control will exercising muscle be under during exercise?
Intrinsic | Will be given priority over several other circulations
70
Kidneys receive ___% of cardiac output at rest
25
71
Why do kidneys receive so much cardiac output?
``` Needs BF for filtering Essential for controlling -pH -ionic levels -fluid balance ```
72
What control will non-exercising muscle be primarily under when exercising?
Extrinsic
73
Decreased tone to smooth muscle causes
Dilation
74
Increased tone to smooth muscle causes
Constriction
75
Kidney primarily under______control at all times
Extrinsic
76
Arterial barorecepors
Pressure receptors that monitor average level of arterial pressure and its rate of change
77
Where are arterial baroreceptors located?
Carotid sinus | Aortic arch
78
Where does info from aortic baroreceptors go?
Nucleus tractus solitarius in medulla
79
What does nucleus tractus solitarius do with info from arterial baroreceptors?
Compares it to set point for atrial pressure If measured pressure is different from set point, hypothalamus alters autonomic outflow to bring pressure closer to set point
80
Arterial baroreceptors are (slow/fast) control
Fast
81
Left atrial receptors
Mechanoreceptors that monitor stretch of left atrial wall
82
Pressure in left atrial wall is directly proportional to
Blood volume
83
Decreased rate of firing of left atrial receptors is perceived as
Less blood volume
84
Where is info from left atrial receptors sent?
Centers like nucleus tractus solitarius in medulla and compares to normal set point for blood volume
85
If measured blood volume is different from set point....
Hypothalamus will change output of ADH (anti diuretic hormone) - decreased blood volume will lad to increased release of ADH
86
Way does ADH do
Acts upon kidney to conserve water
87
Congestive heart failure
Left atrial exceptions are damaged, or set point changes
88
Renal sympathetic response in left atrial feedback loop is an exception to what?
Sympathetic system being divergent; this is point to point control
89
Renin-angiotensin
Hormone system entirely within kidney which has significant effect upon controlling BP, especially when arterial pressure drops Looked at as a mechanism to protect renal blood flow, but also seems to be significant in protecting systemic arterial pressure
90
JGA stimulates release of
Renin
91
Renin
Enzyme produced by kidney | More released when kidney senses drop in arterial pressure at level of kidney
92
Angiotensinogen
Protein in blood that comes from liver
93
What does renin do
Acts upon angiotensinogen and produces angiotensin I
94
Angiotensin I
Has no physiological effects
95
What does angiotensin I do?
Converted to angiotensin II in lungs by converting enzyme
96
Angiotensin II
Most potent vasoconstrictor in body, also stimulates retention of sodium in kidney
97
What happens to angiotensin II
Converted to angiotensin III by enzyme in blood plasma
98
Angiotensin III
Same effects as angiotensin II, but better at release of aldosterone
99
What does angiotensin III do
Releases aldosterone
100
Converting enzyme inhibitors
Drug class to block converting enzyme for hypertension patients
101
Hypertensive patients have..
Faulty JGA

Physiology (17 decks)

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