Physiology- Heart

Question 1

The cardiac muscles are myocytes

- they are myogenic, meaning?

Answer 1

• is able to contract on its own without needing nerve impulses

Question 2

What is known as the pacemaker of the heart?

Answer 2

Sing-atrial node

Question 3

What is the purpose of the SA node and where is it?

Answer 3

• contracts and transmits electrical impulses throughout atria, causing both atrium to contract
• top of right atrium

Question 4

Process of atrial systole:

Answer 4

• atria contract
• SAN contracts and transmits electrical impulse causing both atria to contract, pumping blood into ventricles
• ventricles are electrically insulated so do not contract
• semi lunar valves close to stop backflow

Question 5

Ventricular systole:

Answer 5

• electrical impulse passes from atrioventricular valve to purkinje fibres
• there is a short delay, then the electrical impulse passes down the insulated walls of the septum as the bundle of His
• at the base of ventricles the purkinje fibres spread out initiating ventricular contraction
• squeezing blood from bottom up, also forcing AV valves shut

Question 6

Diastole:

Answer 6

Atria and ventricles relax, while atria fills with blood

- semi lunar valves are shut as ventricular pressure drops below arterial pressure

Question 7

What is a phonocardiogram?

Answer 7

A recording of the sounds made by the heart, due to AV and semi-lunar valve closing

Question 8

What is an electrocardiogram and its use?

Answer 8

• a recording of the hearts electrical activity

- diagnostics of heart problems can be made from weird electrical activity

Question 9

Equation for cardiac output?

Answer 9

Cardiac output= heart rate x stroke volume

Question 10

What is the equation for measuring heart rate?

Answer 10

Heart rate=60/cycle time(s)

Question 11

What is stroke volume?

Answer 11

Volume of blood pumped in each beat

Question 12

What is an atheroma and how is it formed?

Answer 12

A collection of Cholesterol and other insoluble lipids on the inside of coronary artery

Question 13

What is an aneurism and how is it formed?

Answer 13

The atheroma hardens to form a rough plaque which weakens artery wall, causing the wall to swell beyond what it should

Question 14

What else can an atheroma lead to other than aneurism?

Answer 14

Coronary thrombosis: the plaque forms a blood clot in the coronary artery

Question 15

What is myocardial infarction?

Answer 15

The death of myocytes due to the lack of oxygen and their inability to respire anaerobically

Question 16

What worsens or causes coronary heart disease?

Answer 16

1) blood cholesterol
2) genetics- blood pressure and fat metabolism are genetic
3) Diet- high levels of saturated fats increases cholesterol, and astheosclerosis (restricted blood flow)
4) smoking- CO and nicotine increase blood pressure
5) blood pressure- high bp increases risk of aneurism and stimulates thickening of artery walls