T2 U2 Physiology of the heart

Question 1

Which 2 systems regulate heart activity

Answer 1

Autonomic system nerves

Nodal System [ Intrinstic Conduction System]

Question 2

Muscle depolarization from atria to ___ is caused by___

Answer 2

Ventricle.

Intrinsic conduction

Question 3

Name the 5 conduction pathways of the conduction system

Answer 3

SA node 
AV node
AV bundle
Bundle Branches
Purkinje fibres

Question 4

The SA Node is a pacemaker in ____

Answer 4

The Right atria

Question 5

What is the function of the AV node

Answer 5

Gap junction of Atria and ventricles. Allows SA Node depolarization to spread to atria and ventricles

Question 6

Why is there a delay b/w impulses in the AV node

Answer 6

Allow atria / ventricles to contract completely

Question 7

Another name for AV bundle ?

Answer 7

Bundle of His

Question 8

Where is Bundle of His loctaed

Answer 8

In interventricular septum

Question 9

Purkinje fibres spread in muscles of

Answer 9

Ventricle wall

Question 10

Function of purkinje fibres

Answer 10

Carry impulse f/r L + R bundle branches to Ventricular Myocardium

Question 11

Name and explain the 2 homeostatic imbalnces that can arise from conduction errors

Answer 11

Tachycardia = Abnormal rapid HR
Bradycardia = Abnormal slow HR

Question 12

ECG stands for

Answer 12

Electrocardiogram

Question 13

Name the waves seen on an ECG, and what they represent

Answer 13

P Wave - Atrial Depolarization
QRS complex - Ventricular Depolarization
T wave - Ventricular repolarization

Question 14

Name and explain the 4 homeostatic imbalances that ecg will pick up

Answer 14

Myocardial infarct - Heart attack
Heart block - HB too slow b/c signals are blocked
Ischemia - Not enough blood supplied
Fibrilation - Irregular HB

Question 15

Define:
Systole
Diastole
Cardiac Cycle

Answer 15

Systole - contraction of ventricles
Diastole - Relax ventricles
Cardiac Cycle - Complete HB

Question 16

Name and explain the 3 periods of the cardiac cycle

Answer 16

Mid-to-late diastole - Heart relax = PSI low. SL valve closed, AVV open. Atria contract = force blood to ventricles

Ventricular Systole - AVV closed, PSI Increased, SLV open = blood flow out, atria relax and fill w/ blood

Early diastole - Ventricles relaxed. SLV closed, Ventricles closed. Inter Ventricular PSI drops, AVV open and ventricles refill

Question 17

Abnormal heart sound

Answer 17

Murmur

Question 18

What is Cardiac output

Answer 18

blood pumped by ventricle per minute

Question 19

what is stroke volume

Answer 19

vol. blood pumped by ventricle per HB

Question 20

When would cardiac output incr.?

Answer 20

If SV or HR or both incr.

Question 21

How is the SV regulated

Answer 21

Starlings law = more stretch = more blood pumped. If one side pumps more = higher venous return to opposite side in order to pump equal amounts

Question 22

What factors modify the HR?

Answer 22

Neural ANS control - emotional/ physical stress

Adrenaline

Ions - electrolyte imbalances eg: Sodium/ potassium, calcium insufficiency/ overload

Exercise