Cardiovascular Physiology

Question 1

P wave (ECG)

Answer 1

Result of depolarisation from SA node to AV node

Question 2

QRS complex (ECG)

Answer 2

Result of the ventricular depolarisation and precedes ventricular contraction

Question 3

T wave (ECG)

Answer 3

Caused by ventricular repolarisation

Question 4

Stroke Volume influenced by:

Answer 4

• Volume of blood in ventricles
• Changes in sympathetic nervous system
• Changes in arterial pressure

Question 5

Regulation of HR

Answer 5

• If blood volume drops, then SV declines and CO is maintained by increasing HR
  * Chronotropic factors
• Controlled by nervous system affecting ion channels
  * Sympathetic increases HR
  * Parasympathetic decreases HR

Question 6

• Respond to changes in arterial pressure
• Highly sensitive to stretch/distortion
• Degree of stretching is directly proportional to blood pressure
• An increase in pressure leads to increase in AP firing
• Short term changes in blood pressure

Answer 6

Arterial baroreceptors

Question 7

• Network of connected neurons
• Medulla oblongata
• Input from various baroreceptors
• Input determines AP frequency CV centre
• Increased firing of baroreceptors, decreased sympathetic outflow, increased parasympathetic outflow
• Decreased arterial pressure, increased plasma concentrations of hormones, which increases arterial pressure by constricting arterioles

Answer 7

Medullary CV Centre

Question 8

• Norepinephrine acts on beta-adrenergic receptors to increase ventricular contractility
• Increased contractility results in greater SV due to a more complete ejection of the end-diastolic volume

Answer 8

SV - Contractility

Question 9

• The ventricle contracts more forcefully during systole when it has been filled to a greater degree during diastole
• Due to length-tension relationship
• End-diastolic volume is determined by how stretched the ventricular sarcomeres are before contraction
• The greater the end-diastolic volume, the more the muscles are stretched and thus greater the contraction

Answer 9

SV - Frank Marlin Mechanism

Question 10

Muscular sack enclosing heart

Answer 10

Pericardium

Question 11

Fixes inner layer of pericardium to heart

Answer 11

Epicardium

Question 12

Muscular wall of the heart formed from cardiac muscle cells

Answer 12

Myocardium

Question 13

Muscular wall separating the ventricles

Answer 13

Atrioventricular Septum

Question 14

Limit movement to prevent backward flow of blood

Answer 14

Papillary muscles

Question 15

• Permit flow from atrium to ventricle
• Left valve - bicuspid
• Right valve - tricuspid

Answer 15

Atrioventricular Valves

Question 16

Blood from right ventricle to pulmonary trunk

Answer 16

Pulmonary semi-lunar valve

Question 17

Blood from left ventricles into aorta

Answer 17

Aortic semi-lunar valve

Question 18

Fasten AV valves to papillary muscles

Answer 18

Chordae tendinae

Question 19

Precapillary sphincter

Answer 19

The site at which a capillary exits from a metarteriole, surrounded by ring of muscle

Question 20

Angiogenesis, and where are factors produced?

Answer 20

• Capillary develop and growth

- Vascular endothelial cells

Question 21

Continuous capillaries

Answer 21

Skin and muscle

Question 22

Fenestrated capillaries

Answer 22

• More permeable

- Intestines, kidneys

Question 23

Sinusoidal capillary

Answer 23

Liver, bone marrow, lymphoid tissues

Question 24

Things that contribute to resistance

Answer 24

• Blood viscosity
• Total blood vessel length
• Blood vessel diameter

Question 25

Percentage of blood volume that is erythrocytes

Answer 25

Haematocrit