physiology

Question 1

ischaemia

Answer 1

lack of blood flow to cells

Question 2

infarction

Answer 2

necrosis (cells die) due to ischaemia

Question 3

3 layers of arteries and veins

Answer 3

• tunica intima
• tunica media
• tunica externa

Question 4

continuous capillaries

Answer 4

• widespread, found in BBB and dermis etc
• pericytes wrap around then and control what enters or leaves

Question 5

discontinuous capillaries

Answer 5

• really big holes to allow blood cell transfer
• found in liver, spleen and bone marrow

Question 6

fenestrated capillaries

Answer 6

• 10x more permeable than continuous - good for fluid exchange
• found in kidneys

Question 7

polarised

Answer 7

intracellular more negative

Question 8

depolarised

Answer 8

intracellular more positive

Question 9

phase 4 - funny current (AVN + SAN)

Answer 9

ion channels slow influx of sodium ions slowly until the potential threshold is reached
these currents cause spontaneous depolarisation of the cell

Question 10

phase 0 - rapid depolarisation (AVN + SAN)

Answer 10

L type calcium channels open, influx of calcium causes rapid depolarisation

Question 11

phase 3 - repolarisation (AVN + SAN)

Answer 11

outward potassium channels open, starts to repolarise and becomes shortly hyperpolarised

Question 12

phase 0 - rapid depolarisation (myocytes)

Answer 12

action potential from surrounding cells increases the membrane potential to its threshold, enough to start depolarisation by opening sodium channels

Question 13

phase 1 - initial repolarisation (myocytes)

Answer 13

sodium gates channels close and outward potassium channels open

Question 14

phase 2 - plateau phase (myocytes)

Answer 14

calcium ion influx through calcium ion channels, slows down repolarisation

Question 15

phase 3 - rapid repolarisation (myocytes)

Answer 15

calcium channels close and even more potassium channels open rapidly so the cell can reachieve its baseline potential

Question 16

phase 4 - resting potential (myocytes)

Answer 16

flat line maintained by an ATPase sodium potassium pump

Question 17

P wave

Answer 17

depolarisation of the atria

Question 18

PR segment

Answer 18

time between end of atrial depolarisation to the start of ventricular depolarisation

Question 19

QRS complex

Answer 19

depolarisation of the ventricles

Question 20

ST segment

Answer 20

beginning of ventricular repolarisation

Question 21

T wave

Answer 21

ventricular repolarisation

Question 22

cardiac cycle’s

Answer 22

1. atrial contraction (atrial systole)
2. ventricular filling (ventricular diastole)
3. isovolumetric contraction (ventricular systole)
4. ventricular ejection (ventricular systole)
5. isovolumetric relaxation (early diastole)
6. ventricular filling (late diastole)

Question 23

CO =

Answer 23

SV X HR

Question 24

what 3 factors is SV determined by

Answer 24

preload - vol blood available in heart
contractility
afterload - arterial pressure against which ventricles need to contract

Question 25

systolic pressure

Answer 25

max aortic pressure after ejection

Question 26

diastolic pressure

Answer 26

min aortic pressure before ejection