Cardiovascular System

Question 1

Normal adult blood pressure

Answer 1

120/80-140/90

Question 2

Normal blood pressure for infant

Answer 2

72-104-37/56

Question 3

List and describe the three layers of the heart wall

Answer 3

Pericardium - outer layer full of blood capillaries and nerve fibres (fiberous sac in the mediastinum)
Myocardium - middle layer full of muscle tissue
Endocardium - inner layer which is non adherent and forms part of the valves of the heart

Question 4

Flow of blood through the heart

Answer 4

Vena cava to the right atrium
Tricuspid valve to right strip ventricular valve
Right ventricle to semi lunar valve to pulmonary valve
Pulmonary artery right and left
To the lungs to pulmonary veins right and left
Bicuspid valve to mitral valve through left atrioventricular valve to left ventricle to semi lunar valve and aortic valve to aorta

Question 5

The hearts electrical sequence

Answer 5

Initiated by the SA node which is the natural pacemaker. This sends electrical impulses to the right atrium, left atrium and AV node simultaneously. Right atrium is closer to the SA node so depolarises before left atrium. AV node impulse is delayed to allow ventricles to fill with blood then send impulses to bundle of His & purkinje fibres. Triggers contraction of the ventricle to send blood to lung or body

Question 6

What is the SA node

Answer 6

Located in the wall of right atria and initiates heartbeat and keeps it regular
Cause atria to contract and if doesn’t work heart beats slower

Question 7

What is the AV node

Answer 7

Located in the base of right atria and signals ventricles to contract. Sends impulses to the bundle of His and ventricular walls
Waves of excitation conducted along the purkinje fibres

Question 8

What is an ECG

Answer 8

Measures the electrical activities of the myocardium during a cardiac cycle
Change in the polarity as heart chambers contract and the relax is measured
Consisted of waves: P, QRS, T
Detects abnormal heartbeat rhythms

Question 9

What is fibrillation?

Answer 9

When the heart is beating rapidly but the contractions are uncoordinated

Question 10

What are the waves in an ECG

Answer 10

P waves - impulses from SA/AV node. Depolarisation of the atria
QRS - depolarisation of the ventricles. Electrical activities of the purkinje fibres
T waves - repolarisation of the ventricles. Going into diastole and then relax

Question 11

What is cardiac output

Answer 11

Average normal adult heart beats about 70 times per minute. Each pumps out about 70mls of blood (SV)

Heart rate x stroke volume = cardiac output

Question 12

Factors affecting heart rate

Answer 12

• hormones
• exercise
• emotional state
• gender
• age
• temperature
• autonomic nervous system

Question 13

What is the blood composed of

Answer 13

Blood cells (45%) 
Plasma (55%) 
- plasma proteins
- inorganic salts 
- hormones
- enzymes 
- antibodies

Question 14

What is the structure of an artery

Answer 14

Thick muscular elastic walls three layer think which can expand to accommodate the increase in blood volume
Carries blood away from the heart

Question 15

What is the structure of a vein

Answer 15

Think elastic walls where valves are present and pressure is lower than arteries
Carries blood towards the heart

Question 16

What is the structure of a capillary

Answer 16

Smallest blood vessel which is one layer thick and walls. Pressure is low and blood flow is slow with diffusion of gases and nutrients

Question 17

What are the three blood cells

Answer 17

• Erythrocytes (red cells)
• Thrombocytes (playlets)
• Leukocytes (white cells)