Cardiac conduction system

Question 1

list down the properties of Cardiac muscle

Answer 1

1- automaticity/ rhythmicity
2- conductivity
3-excitability
4- contractility

Question 2

The ability of heart to beat spontaneously and regularly is known as_______
A- automaticity/ rhythmicity
B- conductivity
C-excitability
D- contractility

Answer 2

A- automaticity/ rhythmicity

Question 3

The ability of the heart to transmit excitation wave is known as______
A- automaticity/ rhythmicity
B- conductivity
C-excitability
D- contractility

Answer 3

B- conductivity

Question 4

The ability of the heart to receive adequate stimulus is known as______
A- automaticity/ rhythmicity
B- conductivity
C-excitability
D- contractility

Answer 4

C-excitability

Question 5

The ability to contract and to pump the blood into circulatory system is known as______
A- automaticity/ rhythmicity
B- conductivity
C-excitability
D- contractility

Answer 5

D- contractility

Question 6

list down the components of the cardiac conduction system

Answer 6

1- SA NODE
2- AV NODE
3- BUNDLE OF HIS
4- LEFT AND RIGHT BUNDLE BRANCHES
5- PURKINJ FIBERS

Question 7

SA node is known as the “ heart natural pacemaker”_____
true
false

Answer 7

TRUE

Question 8

where is the SA node located

Answer 8

superior lateral wall of right atrium near the superior vena cava

Question 9

what is the function of SA node

Answer 9

initiates the electrical impulse that causes the atria to contract and SETS THE HEART RATE

Question 10

the normal heart rate is ____ beats/min
A- 70-120
B- 50-80
C-60-100
D- 60-120C

Answer 10

C- 60-100

Question 11

what is the name of the tracts that connects the SA node and AV node

Answer 11

internodal tracts

Question 12

list the name of the 3 internodal tracts

Answer 12

• anterior
• middle
• posterior

Question 13

the only conducting pathway between the atria and ventricles is called

Answer 13

AV node

Question 14

where is the av node located

Answer 14

posterior septal wall of right atrium behind tricuspid valve

Question 15

what is the function of the AV node

Answer 15

it delays to ensure the ventricle is filled up before contracting

Question 16

the delay that happens at the AV node is called

Answer 16

Nodal delay

Question 17

what happens if the SA node got damaged

Answer 17

the AV node acts as a pacemaker but generate slower impulses

Question 18

what is the function of bundle of his

Answer 18

group of fibers that carries electrical impulses from the Av node to ventricles

Question 19

where is the bundle of his located

Answer 19

originates from Av node then travels down through the interventricular septum and divides into the right and left bundle branches, which continue down the septum toward the ventricles.

Question 20

the left branch divides into

Answer 20

anterior and posterior fasciculus

Question 21

known as the fastest and largest conducting fiber

Answer 21

purkinje fibers

Question 22

location of purkinje fiber

Answer 22

spread throughout ventricular walls

Question 23

function of purkinje

Answer 23

conduct the electrical impulse rapidly, ensuring coordinated ventricular depolarization and contraction, which is essential for efficient blood pumping

Question 24

where do the purkinje fibers pass the impulse

Answer 24

to ventricular myocytes in ventricular walls

Question 25

steps of SA node AP

Answer 25

1- pacemaker potential: na will flow in and set rate of heart
2- depolarization : happens after na flows in and then reaches the threshold then depolarization occurs ca gate channels open
3- repolarization occurs then and its caused by K+ outflow

Question 26

steps of ventricular AP

Answer 26

1- Depolarization is due to Na influx through fast gated channels
2-Plateau phase is due Ca influx through slow channels
3- Repolarization Ca channels closes and K + channels opened so K efflux which brings membrane potential back to its resting voltage

Question 27

why cardiac muscles cant be tetanized

Answer 27

due to long refractory period

Question 28

what are the two components of autonomic NS that affect heart function

Answer 28

-sympathetic
-parasympathetic(vagal)

Question 29

how does the vagal tone affect the heart rate at rest

Answer 29

reduces the resting heart rate 60-80 beats per minute

Question 30

what affect does sympathetic stimulation have on heart function

Answer 30

-increases heart rate and
strength of heart contractions
- maximal stimulation can triple the frequency of heartbeat and double contraction

Question 31

name two hormones that affect the heart function

Answer 31

thyroid hormone
catecholamines

Question 32

which ions are important for heart function

Answer 32

calcium
potassium

Question 33

three drugs that can affect heart function

Answer 33

• calcium channel blockers
• beta androgenic blockers
  -adenosine

Question 34

characteristics of normal sinus

Answer 34

1-AP originates in sa node
2- regular sa node impulses at 60-100 impulses /min
3- correct sequence and timing for heart activation

Question 35

at rest which is dominant vagal or sympathetic

Answer 35

vagal

Question 36

define intrinsic heart rate

Answer 36

rate at which the heart would beat if there were no external influences. For a typical healthy person, this rate is around 100-110 beats per minute

Question 37

what happens if stimulation of right vagus occurred

Answer 37

the heart slows down by inhibiting the sa node

Question 38

what happens if stimulation of left vagus occurred

Answer 38

will slow down Av conduction

Question 39

parasympathetic initiated cardiac responses are mediated by what

Answer 39

acetylcholine