Cardiac Phsyiology

Question 1

Types of heart failure

Answer 1

1. Heart failure with reduced ejection fraction (left ventricular systolic dysfunction)
2. Heart failure with preserved ejection. fraction (diastolic heart failure)
3. Right side heart failure

Question 2

Electrical conduction of the heart

Answer 2

1. Sinoatrial node
2. Atrioventricular node
3. Bundle of his
4. Right and left bundle branches
5. Purkinje fibres

Question 3

ECG

Answer 3

1. P wave – depolarisation of atria
2. QRS– depolarisation of the septum and right and left ventricles
3. T wave – ventricular repolarisation produced by the ventricular cells returning to their resting state

Question 4

Stages of a single heartbeat

Answer 4

1. Atrial depolarisation
2. Contraction of the atria
3. Forces blood into ventricles
4. P wave
5. Ventricular depolarisation forces blood into systemic and pulmonary circulation systems
6. QRS wave
7. Atrial. and ventricle depolarisation
8. Relaxation and refilling with blood
9. T wave

Question 5

Disruptions to electrical activity

Answer 5

1. Atrial fibrillation
2. Supra-ventricular tachycardia
3. Heart blocks
4. Ventricular tachycardia
5. Ventricular fibrillation

Question 6

What is blood pressure ?

Answer 6

1. Blood pressure is the force exerted by blood on the inner walls of blood vessels
2. The heart forces blood through the blood vessels against the resistance of the peripheral blood vessels. this generates a pressure in the circulatory system known as blood pressure

Question 7

Homeostatic control of blood pressure

Answer 7

1. Heart activity
2. Blood volume and viscosity
3. Blood vessels

Question 8

Regulation of heart rate - parasympathetic and sympathetic

Answer 8

1. The heart is supplied by both sympathetic and parasympathetic nerves which originate in the cardiac centre in the medulla
2. Parasympathetic activity slows heart rate
3. Sympathetic activity speeds up the heart rate

Question 9

Cardiac output =

Answer 9

Heart rate x stroke volume

Question 10

Regulation of blood volume

Answer 10

1. Blood pressure is directly proportional to the volume of blood in the cardiovascular system
2. The hormonal control of fluid volume contributes to blood pressure but is slower than nervous control of the heart rate or peripheral resistance
3. The role of hormones in controlling blood volume and therefore blood pressure

Question 11

Peripheral resistance

Answer 11

1. (The force created by the friction between blood and the walls of blood vessels is called peripheral resistance)
2. The resistance to blood flow which is mainly created by the diameter of the blood vessels in the peripheries
3. Contraction of the smooth muscle in blood vessels results in vasoconstriction and increased blood pressure
4. Relaxation of smooth muscle in blood vessels in vasodilation and decreased blood pressure

Question 12

Vasomotor centre

Answer 12

In the medulla and detects sympathetic impulses to contract in the arterioles

Question 13

Blood pressure =

Answer 13

Cardiac output x total peripheral resistance

Question 14

Short term control

Answer 14

1. The short term control of blood pressure is achieved by both the cardiac centre and vasomotor centre location in the medulla part of the brain stem
2. These centres responds swiftly to information received by baroreceptors

Question 15

Baroreceptors

Answer 15

1. Pressure sensitive receptors that detect changes in stretch in the artery walls due to blood pressure changes and send signals to both centres in the medulla
2. Less flow or decreased blood pressure causes baroreceptors to send fewer impulses to both the cardiac and vasomotor centres in the medulla