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Medical Conditions > Cardiac & Vascular Phyisiology and Nervous System Control > Flashcards

Cardiac & Vascular Phyisiology and Nervous System Control Flashcards

1
Q

Describe the function of the fibrous “skeleton” of the heart

A

Continuous arrangment of muscle from endo to epicardium that “wrings” blood from the heart

Prevents conduction abnormalities and supports the heart valves

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2
Q

Describe how the Valve Apparatus Functions

A

Powered by pressure gradient that moves blood from atria to ventricle to ventricle to atria

Ventricular pressure only 1-2mmHg higher than the atria

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3
Q

CV Functions

A

Pump
Deliver & distribute and exchange nutrients, metabolites, hormones, & respiratory gases
Capacitance function

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4
Q

Capacitance Function of CV

A

venous system stores blood for access during stress (ex: actual stress, exercise, etc)

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5
Q

Temporary Pacemaker of the Heart

A

epicardial electrode

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6
Q

Permanent Pacemaker of the Heart

A

Endocardial electrodes

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7
Q

T or F: The heart develops it’s own action potential

A

True! The heart’s contraction does NOT depend on nervous system activation

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8
Q

Intercalated Discs w/ Gap Junctions in Cardiomyocytes

A

Conduction of electricity through gap junctions which connects cytoplasm between cells allows heart muscle to contract as one

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9
Q

Cardiac ECC and CICR

A
  1. Action potential is conducted to contractile cardiomyoctes where it activates calcium channels in the T-Tubules
  2. Ca2+ releases from SR and activates RyR’s which triggers more Ca2+ release (CICR)
  3. Ca2+ in cyctoplasm binds to cardiac troponin-C and moves tropnoin-tropomyosin regulatory complex away from actin binding site for free actin-myosin binding (ECC)
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10
Q

What makes up one cardiac cycle

A

One systole and one diastole with diastole making up 2/3 ish of the cycle

Diastole is when the heart “feeds itself”

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11
Q

Phases of the Cardiac Cycle

A

Atriole Systole Begins
Ventricular Systole (First Phase)
Ventricular Systone (Second Phase)
Ventricular Diastole (Early)
Ventricular Diastole (Late)

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12
Q

Atriole Systole Begins

Phases of the Cardiac Cycle

A

Atrial contraction forces blood into ventricles

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13
Q

Ventricular Systole (first phase)

Phases of the Cardiac Cycle

A

Ventricular contraction pushes AV valves closed

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14
Q

Ventricular Systole (second phase)

Phases of the Cardiac Cycle

A

Semilunar valves open and blood is ejected

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15
Q

Ventricular Diastole (early)

Phases of the Cardiac Cycle

A

Semilunar valves close and blood flows into atria

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16
Q

Ventricular Diastole (late)

Phases of the Cardiac Cycle

A

Chamers relax and blood fills ventricles passively

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17
Q

Heart Rate

A

frequency of contraction

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18
Q

Preload

A

end disatolic volume (EDV)

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19
Q

Afterload

A

stress in the wall of the left ventricle during ejection or resistance to ejection due to:

SVR: Systemic Vascular Resistance
TPR: Total Peripheral Resistance

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20
Q

Contractility

A

innate ability of the heart muscle to contract and generate force

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21
Q

Afterload and Stroke Volume Relationship

A

inverse assuming constant blood flow

A decrease in afterload leads to an increased stroke volume and vice versa

Anrep Reflex: w/ abrupt increase in afterload, contractility increases to prevent dangerous decreases in SV

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22
Q

T or F: The Conduction System is sub-endocardial

A

True!

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23
Q

SA Node Firing Rate

A

60 - 100

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24
Q

AV Node Firing Rate

25
Ventricular / Purkinje System Firing Rate
20 - 40
26
T or F: The pace of the heart is whatever is firing the fastest
True! If the SA node isn't firing it has been overpowered
27
How does the parasympathetic nervous system change the cardiac system
Does not change contractile function due to nerve endings in the atria (SA & AV nodes) *Can change heart rate*
28
How does the sympathetic nervous system change the cardiac system
Nerve fibers supply the SA & AV nodes and the muscle of the atria and ventricles *Can change contractile function & rate*
29
Are there more B2 or B1 receptors in the heart?
B1
30
Describe NE's impact on the cardiomyocyte
SNS releases NE which connects to B1 receptors on cardiomyocytes and increases *all* of the following: Chronotrophy: HR Dromotrophy: conduction velocity Inotrophy: contractility of myocardium Lusitrophy: relaxation of myocardium (more rapid rate)
31
Effect of Epinephrine & NE on a1 receptors located in vascular smooth muscle
Vasoconstriction
32
Effect of Epinephrine & NE on B1 receptors located in heart
Increased HR, contractility, and conduction velocity
33
Effect of Epinephrine & NE on B2 receptors located in vascular smooth muscle & coronary arteries
vasodilation
34
How many Cardiac Reflexes Are There?
5! Baroreceptor Reflex Frank-Starling Mechanism Force-Frequency Relationship Atrial Strech Reflex Anrep Reflex
35
Baroreceptor Reflex
Baroreceptors act as the foot on the brake for sympathetic outflow As *BP decreases, baroreceptor firing rate decreases* (= foot off the brake) and *sympathetic outflow increases*
36
Frank Starling Mechanism
The ability of the heart to change its force of contraction and thus SV in response to changes in venous return As *venous return increases* (more blood in the atria = atrial stretch & is able to
37
Force Frequency Relationship (aka Treppe, Bowditch, etc)
Decreases in diastolic fill time + increases in HR result in increases in contractile force
38
Atrial Stretch Reflex (aka Bainbridge Reflex)
As we inhale we cause *increased venous return* which *stimulates stretch receptors in the R. atrium* *Afferent impulses through the inferior cervical sympathetic nerve* cause *inhibition of vasodilators* Causes a *decrease in vagal tone* *Tachycardia*
39
T or F: Arteries and veins have the same proportion of vasculature
FALSE They have the same components but different vasculature proportions
40
T or F: Capillaries are the most permeable exchange vessels and have the most surface area
True! Capillaries increased SA make them the most *continuous & slow* vessels = best for gas/nutrient exchange
41
T or F: Total Peripheral Resistance (TPR) is determined at the level of the arteriole
True!
42
Windkessel Effect
The aorta is elastic and stretches + recoiles during diastole to continue pushing blood forward through the system Keeps blood flow from being phasic and clotting at the heart
43
T or F: Small arteries and arterioles regulate BP by altering peripheral resistance and regulate blood distribution to capillary beds
True!
44
Describe the function of capillaries
Due to high permeability and slow flow, are placed directly next to tissues so diffusion is possible Provide *large cross-sectional area for exhange* Single layer of endothelial cells + permiablility
45
Describe the difference between continuous and discontinuous/sinusoidal capillaries
Continuous capillaries *do not* allow RBC leakage and are located in skeletal muscle Discontinuous allow RBC leakage
46
Describe how osmosis relates to Microcirculation and the relationship between capillaries and lymph vessels
H2O leaks out of arterial capillaries into lymph vessels due to solutes in interstitial space and blood becomes more concentrated Osmosis on the venous capillaries pull water back into blood (not 100% though and lymph keeps that)
47
Starling's Forces & Microcirculation
Starling's forces are a balance between Filtration & Absorption
48
Purpose of Veins
Return blood to the heart *Capacitance Vessels* which reserve blood for times of stress But if one valve fails (failure of pressure gradient system to return blood to heart) the whole system begins to cascade into pressure overload in the periphery = vericose veins
49
Describe Ohm's Law in terms of Blood Flow
When there is a voltage gradient, current will flow in a manner that is proportional to the wire's resistance *Resistance and blood flow have an inverse relationship* and *changes in pressure is directly proportional to blood flow* Q = change in P/R (I = V/R)
50
Describe the importance of Radius^4 to Vascular Resistance & Blood Flow
As radius increases, vascular Resistance decreases and blood flow changes *small changes in arteriole radius creates a BIG change in blood pressure* (b/c ^4)
51
Describe how the system actively dictates where blood needs to go during exercise
*blood flow is not due to a total systemic change* Increase sypmathetics causes increased venous return through systemic vasoconstriction which increases CO to working mm. However the working mm. still needs nutrients and waste removal so *local* factors increase vasodilation in mm. to accomplish that
52
In the periphery low blood O2 is a ...
Vasodilator
53
In the lungs, low blood O2 is a ...
Vasoconstrictor
54
Autoregulation
the ability of an organ to maintain a constant blood flow despite changes in perfusion pressure aka *Local b.f. Regulation* ex: cerebral perfusion to maintain cerebral b.f. within normal range
55
Describe how a stroke may affects a person's autoregulation
If someone is accustomed to a higher BP over time, their "normal" auto-regulation moves up on the Y axis and bringing their BP down must be done in a controlled manner to prevent the system from being shocked
56
Systolic BP
pressure exerted during ventricular systole
57
Diastolic BP
pressure exerted during ventricular diastole
58
T or F: BP is the most significant force contributing to Afterload
True!
59
Mean Arterial Pressure (MAP)
Avg. BP during a single cardiac cycle Represents organ perfusion pressure and how well blood is flowing to tissues and organs *Normal: 70 - 110 mmHg* If MAP <60 mmHg for prolongued time, tissues and organs do not receive enough blood flow

Medical Conditions (3 decks)

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