Chapter 9

Question 1

What is meant by the cardiac Muscle Works as Syncytium

Answer 1

The cardiac Muscles belonging to certain region ( Ie ventricles/ Atria) Contract as one and fnx as one cell

Question 2

What are the Advantages of the cardiac muscle functioning as a Syncytium?

Answer 2

Speeds Up conduction

AP travels easily

Question 3

The division of the muscle of the heart into ___ functional syncytium allows for?

Answer 3

Two. Atrial and ventricular Syncytium.

The atria to contract a short time ahead of ventricular contraction

Question 4

What separates the each of the syncytium

Answer 4

Fiberous Tissue: The annulus Fibrosis

Question 5

What other function does the Annulus fibrosis have?

Answer 5

Electrically insulates the nodes of the heart

Question 6

What allows for quick almost free diffusions of Ions?

Answer 6

Gap Junction

Question 7

What would happen if the gap junctions shrunk in size?

Answer 7

AP’s travel slower

Question 8

What’s the arrangement of the heart muscles cells

Answer 8

Interlacing bundles of cardiac muscle fibers arranged spirally around the circumference of the heart.

Question 9

What is the advantage of the spiral arrangement?

Answer 9

A twisting effect is produced, efficiently pushing blood upwards towards the exit of the major arteries of the heart

Question 10

*What causes the ventricular cardiac muscle contraction to last longer than skeletal muscles cell contraction?

Answer 10

The presences of a plateau in the AP.

Question 11

What cause a presences of a plateau in the AP?

Answer 11

the membrane remains depolarized for about 0.2 s, giving a plateau

Question 12

What happens during each membrane potential Phase?

Ionic Phase leading to AP

Answer 12

phase 0- Fast Na+ channels open then slow Ca++ channels
phase 1- K+ channels open
phase 2- Ca++ channels open more
phase 3- K+ channels open more
phase 4- Resting membrane potential

Question 13

Each cycle is initiated by a ______ generation of an ____ in the ___ ____

Answer 13

Spontaneous
AP
SA Node

Question 14

Is there a delay in the conduction between the atria and the ventricles. Why or why not?

Answer 14

yes, so that way the atria can contract into the ventricle’s before the ventricles contract:
-> atria pump more blood into the ventricles prior to ejection

Question 15

The cardiomyocytes re-establish the Na+/K+/Ca2+ gradient during which Period of the cardiac cycle?

Answer 15

Diastole ( Phase of relaxation)

Question 16

The heart fills with blood during which p0hase of the cardiac cycle

Answer 16

diastole

Question 17

The period where the heart contracts is?

Answer 17

Systole

Question 18

What causes the P-wave?

Answer 18

spread of depolarization through the atria, this is followed by atrial contraction

Question 19

the QRS waves appear as a result of

Answer 19

, electrical depolarization of the ventricles

Question 20

Ventricular T wave represents

Answer 20

Repolarization of the ventricles:

-> when the ventricle muscle fibers begin to relax

Question 21

The Pace Maker of the heart is?
a. SA node
b. AV node
c. Purkyngi Fibers
d. Hypothalamus
e a & b
f. a & d

Answer 21

A.

Question 22

What is reponsible for the electrical activity found at the START of the P-wave

Answer 22

SA nodal fibers send a signal to contract

Question 23

*Aortic Pressure start ___ after the ____ open during systole

Answer 23

Increasing;

AV valves

Question 24

Aortic Pressure starts ____ after the end of the ejection phase

Answer 24

Decreasing

Question 25

What happens after the aortic valves closes? And what is this phenomena called

Answer 25

Sudden back-flow towards the left ventricle: This is known as an Incisura

Question 26

True or false. Aortic pressure increase slowly during diastole because of the Plastic nature of the aorta

Answer 26

False. Aortic Pressure decreases after diastole due to the ELASTICITY of the aorta

Question 27

What is preload? What is it’s significance

Answer 27

also known as the left ventricular end-diastolic pressure ), is the amount of ventricular stretch at the end of diastole.

Question 28

What is afterload?

Answer 28

the amount of resistance the heart must overcome to open the aortic valve and push the blood volume out into the systemic circulation. (systemic vascular resistance (SVR)

Question 29

What is the Frank-Starling Mechanism?

Answer 29

It’s the hearts ability to respond and adapt to incoming blood flow. The more blood in = the more blood: Due to stretching of the muscles. ( No extra work is needed )

Question 30

Sympathetic stimulation of the heart effects CO in which way?

Answer 30

Increase = CO= SVxHR -> sympathetic stim increases HR

Question 31

In which ways do Sympathetic Stimulation effect the heart?

Answer 31

Increases HR, force of contraction, and thereby increasing vol of blood pumped

Question 32

True or false. Under normal conditions, sympathetic nerve fibers to the heart discharge continuously at a slow rate

Answer 32

True.

Question 33

____ _____ stimulation can stop the heart for a few seconds

Answer 33

Strong parasympathetic
// Vagal

Question 34

The vagal never fibers are located where on the heart?

Answer 34

Mainly on the atria

Question 35

Fever greatly ____ heart rate

Answer 35

Increases

Question 36

In what ways does the alertration of the HR ouccur via heat?

Answer 36

increases permeability of cardiac muscle membrane to ions that control heart rate.
Contractile strength of the heart is often enhanced temporarily by a moderate increase in temperature

Question 37

Prolonged heat elavation can effect the heart how?

Answer 37

Exhausts metabolic systems of the heart and eventually causes weakness