Chapter 31

Question 1

What does Toponin I do?

Answer 1

binds to actin in thin myofilaments to hold the troponin-tropomyosin complex in place

Question 2

What does Troponin T do?

Answer 2

Binds to tropomyosin to the thin filaments

binds to tropomyosin, interlocking them to form a troponin-tropomyosin complex

Question 3

What does Troponin C do?

Answer 3

Binds to Ca2+ to thin filament for muscle contraction.

Question 4

Depolarization of myocardial cell stimulates opening of VG Ca2+ channels in ______????

Answer 4

sarcolema

Question 5

______ is released, causing the power stroke to occur.
Power stroke pulls actin toward the center of the ___ band

Answer 5

Pi (an inorganic phosphate group)

A band

Question 6

If there is an increase in need of oxygen by the coronary blood vessels, what substance dilates the cornary blood vessels?

Answer 6

Adenosine

Question 7

What are the site of inpulse fromation in the SA node?

Answer 7

P cells

Question 8

Does the SA node or the AV node have thicker fibers?

Answer 8

AV node

(also more resistance to conductane)

The slower AV node allows for additional ventricular filling time

Question 9

What are the layers of heart muscle

Answer 9

Question 10

Does it start in Endocardium or Epicardium

Activation?

Deactivation?

Answer 10

Activation

Endocardium to epicardium.

Deactivation

Epicardium to endocardium

Question 11

In phase 4 what is the voltage threshold

Answer 11

-40mV

Question 12

What phase of cardiac pacemaker action potential does repolarization take place?

Answer 12

Phase 3

Question 13

Discribe the phases of cardiac muscle action potential

Answer 13

Phase 0: depolarization:
VG Na+ channels open.
Inward diffusion of Na+.

Phase 1: early repolarization:
VG Na+ channels rapidly close.
VG Ca2+ channels open

.
Phase 2: plateau phase:
Rapid reversal in membrane polarity to –15 mV.
Slow inward flow of Ca2+ balances outflow of K+.

Phase 3: rapid repolarization:
VG K+ channels open.

Phase 4: resting membrane potential:
-80 to –90 mV.

Question 14

Explain what is occurring during each phase of the cardiac cycle

Answer 14

Rapid filling of ventricles:

AV valves open.

Atrial systole:

P wave occurs.

Atrial contraction.

Isovolumetric contraction:

QRS just occurred.

AV valves close.

Semilunar valves are closed.

Ejection:

Semilunar valves open.

AV valves are closed.

Isovolumetric relaxation:

T wave occurs.

Semilunar valves close.

AV valves are still closed.

Ventricular pressure drops below atrial pressure.

AV valves open.

Question 15

First heart sound:

Second heart sound:

Third heart sound:(not normally heard)

Fourth heart sound:(only heard if pathologic)

Answer 15

First heart sound:

Produced immediately after QRS wave.

Rise of intraventricular pressure causes AV valves to close.

Second heart sound:

Produced after T wave begins.

Fall in intraventricular pressure causes semilunar valves to close.

Third heart sound:

Tensing of the chordae tendineae during rapid filling and expansion of the ventricle.

The third heart sound is normal in children, young adults, and some trained athletes.

Fourth heart sound:

It is a sign of a pathologic state.

Sound of blood being forced into a stiff/hypertrophic ventricle.

Question 16

What does the intracardiac pressure venous C Wave represent?

Answer 16

Represents the bulging of the mitral valve into the left atrium during early systole.

Question 17

What has the following influences?

Rate of impulse generation, depolarization, and repolarization of myocardium.
Strength of atrial and ventricular contraction.

Answer 17

Autonomic nervous system influences

Question 18

What has the following influences?

§nnervates all parts of the atria and ventricles.
Shortens conduction time through the AV node.
Increases rhythmicity.
Enhances myocardial performance.

Answer 18

Sympathetic nervous system influences

Question 19

Alpha 1 = Does what

Alpha 2= Does what

Beta 1 = Does what

Beta 2 = Does what

Answer 19

Alpha 1 = Constricts coronary arteries (NE)

Alpha 2= Vasodilation (by restricting NE release)

Beta 1 = Increases HR and force of contraction (NE)

Beta 2 = Causes coronary arterioles to dilate (Epi)

Question 20

study this

Answer 20

Study pic

Question 21

What does this defination describe?

states that the stroke volume of the heart increases in response to an increase in the volume of blood filling the heart (the end diastolic volume) when all other factors remain constant.

Answer 21

Frank–Starling law

Question 22

How is Stroke Volume related to TPR?

Answer 22

SV inversely proportional to TPR.
Greater the TPR, the lower the SV

Question 23

Laplace’s Law deals with what general topic

Answer 23

Wall tension

Question 24

What is the formula for Cardiac Output?

Answer 24

CO = SV X HR

Question 25

What are the 3 variables of stroke volume?

Answer 25

**_EDV:_** Volume of blood in the ventricles at the end of diastole. **_TPR:_** Frictional resistance to blood flow in the arteries. **_Contractility:_** Strength of ventricular contraction.

Question 26

Where is the major cardiovascular control center located?

Answer 26

Medulla

Question 27

What causes HR to increase after IV infusions of blood or other fluid? Reflex mediated by volume receptors in atria.

Answer 27

Bainbridge reflex:

Question 28

What are the two main factors that determine the force of contraction?

Answer 28

Preload Aleterations in sympathetic activation

Question 29

What is a normal ejection fraction?

Answer 29

Normal is 60-75%

Question 30

How do inotropic agents affect contractility?

Answer 30

+ inotropic agents increase the velocity of myocardial contraction and SV. - inotropic agents decrease the velocity of myocardial contraction and SV.

Question 31

What are the factors that affect blood flow

Answer 31

**1)The pressure diffrence (aorta vs Rt atrium)** **2)Resistance** R = ln/r(4) l = length of the vessel n = viscosity of blood r = radius of the vessel

Question 32

What is the mean arteral pressure

Answer 32

Average arterial pressure during the cardiac cycle MAP = (cardiac ouput X TPR) Central venous pressure(very small and inconsequential) or estimate like this = diastolic pressure + 1/3 (Systolic - diastolic)

Question 33

Where is the greatest pressure drop in vascular system?

Answer 33

In Arterioles

Question 34

If you are measureing total resistance in a **_series_** what do u do? If you are measuring total resistance in **_parallel_** what do u do?

Answer 34

**_Series:_** Total resistance = sum obtained by adding all the individual resistances using Poiseuille’s Law. **_Parallel:_** Total resistance = sum of reciprocals of individual resistances. If cross-sectional area is made up of a very large # of parallel vessels, resistance will be greater

Question 35

**_The following factors are reasons that\_\_\_?\_\_would be released_** Drop in BP in renal artery. Decrease Na+ and Cl- delivered to kidney. Stimulation of b-adrenergic receptors. Angiotensin II. Low [K+].

Answer 35

Factors control renin release

Question 36

Which angiotensin receptors have proinflammatopry effect: Cause Myocyte hypertrophy and vasoconstriction

Answer 36

AT1

Question 37

Which angiotensin receptors have counterregulatory mechanism: Which mediates vasodilator/natriuretic cascade.

Answer 37

AT2 receptors

Question 38

What does the following describe? Stretch of atria stimulates production of ANP and BNP. Increase Na+ and H20 excretion. Antagonistic to aldosterone and angiotensin II.

Answer 38

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP)

Question 39

Where is urodilatin produced and what is it?

Answer 39

Kidney Diuretic

Question 40

What is adrenomedullin ADM?

Answer 40

Local/paracrine factor, synthesized and secreted from vascular endothelial and smooth muscle cells. Vasodilator

Question 41

Bradykinin, prostacyclin, and endothelin-1 are all what?

Answer 41

Vasodilators

Question 42

What is the major paracrine produced in the endothelium

Answer 42

NO

Question 43

When does most coronary blood flow occur?

Answer 43

during diastole