Cells & Tissues

Question 1

What is the bulk of the heart muscle made up of?

Answer 1

Myocardium

Question 2

What is the inner surface of the myocardium made up of?

Answer 2

Endothelium

Question 3

What does the right ventricle pump?

Answer 3

Deoxygenated blood to the lungs

Low pressure 25mmHg

Little resistance to blood flow

Short distance to the lungs

Question 4

What does the left ventricle pump?

Answer 4

Oxygenated blood to all organs of the body

Higher pressure 120 mmHg

Thick muscular wall

Question 5

Outline the valves of the heart;

Answer 5

• atrioventricular (bicuspid/mitral/tricuspid)

•semi lunar valves (aortic & pulmonary)

Question 6

What are atrioventricular valves attached to?

Answer 6

Chordae tendinae

Question 7

What is the tension of the chordae tendinae regulated by?

Answer 7

Papillary muscles

Question 8

When ventricles contract what also contracts? And what does this cause?

Answer 8

Popularly muscles also contract

Tightens the chordae tendinae and prevents the valve cusps from everting into the atria

Question 9

Give some characteristics of cardiac muscle;

Answer 9

Fibres arranged in a latticework

Fibres divide,recombine & spread

Striated appearance

Myofibrils contain actin & myosin

Question 10

What are intercalated discs?

Answer 10

Cell membranes that separate individual cardiac muscle cells

At each disc cell membranes fuse together

Allow rapid diffusion of ions

Question 11

What 2 syncytiums is the heart composed of?

Answer 11

Atrial syncytium - two walls of the area

Ventricular syncytium - two walls of the ventricle

Question 12

What is the average for action potential?

Answer 12

105mV

Question 13

What is the sequence of excitation?

Answer 13

Involves increase in cytosolic calcium

Contraction of atria & ventricles must be coordinated to prevent AV valves closing during ventricle filling

Question 14

What are the action potential of the cardiac muscle fibres 3 phases?

Answer 14

1. Rapid depolarisation - voltage gates Na+ channels open
2. Plateau - voltage gates Ca2+ channels open
3. Depolarisation - voltage gated K+ channels open, K+ outflow

Question 15

Describe the P wave of the ECG;

Answer 15

• SA node fires, atrial depolarisation
• atrial systole

Question 16

Describe the QRS complex of the ECG;

Answer 16

• AV node fires, ventricular depolarisation
• ventricular systole

Question 17

Describe the T wave of the ECG;

Answer 17

Ventricular repolarisation

Question 18

What’s the name for the heart initiating its own impulse?

Answer 18

myogenic

Question 19

What is the myogenic motion controlled by?

Answer 19

Controlled by cardiovascular centre located in ventrolateral medulla

Question 20

What 2 systems work to oppose each other?

Answer 20

SNS

PNS

Question 21

What is the function of SNS?

Answer 21

Accelerates hearts actions

Increase in rhythm

Force of contraction

Excitability increased

Question 22

What is the function of PNS?

Answer 22

decrease in chronotropic effect

Decelerates the hearts actions

Inotropic effect

Question 23

What is the function of endocrine hormones?

Answer 23

Released from the adrenal gland, adrenaline & dopamine are all involved in the initiation of the “fight or flight” response

Question 24

What is the function of endocrine hormones?

Answer 24

Released from the adrenal gland, adrenaline & dopamine are all involved in the initiation of the “fight or flight” response