L 11 Control of Cardiac output

Question 1

Haemodynamic?

Answer 1

• Physics of blood

Question 2

What is Darcy’s law FORMULA?

Answer 2

Flow = Change in pressure
————————-
Resistance

Question 3

What factors affect rate at which fluid comes out? (2) remember Darcy’s equation

Answer 3

• Pressure
• Vascular resistance

Question 4

What does vascular resistance subdivide into?

Answer 4

• Vessel length
• Blood viscosity
• Vessel radius

Question 5

What factor in vascular resistance has a proportional flow to the power of 4?

Answer 5

Vessel radius

Question 6

• The radius of blood vessel A is 0.5 cm, blood vessel B has radius that is 1.5 cm? How many times is the rate greater in blood vessel B?

Answer 6

bv A = 0.5 cm, B = 1.5 cm, blood vessel B 3x times bigger than A
- flow = r^4 = 3^4 = 81x greater flow in Blood vessel B

Question 7

Where is blood flow greater in the aorta or vena CAVA? Aorta = smaller radius than Vena CAVA

Answer 7

Aorta, although the Vena Cava might have a larger lumen so bigger radius, the aorta has a very high pressure which increases flow significantly.

Question 8

What properties of the artery ensures continuous blood flow?

Answer 8

Stretching/expand and recoiling
During systole contraction = EA stretch
During systole relaxation= EA recoil generating pressure which forces the blood further down the capillary where blood pressure is lower

Question 9

Which artery is used to measure arterial blood pressure GRADIENT ?

Answer 9

Brachial artery

Question 10

What is the range of ideal blood pressure/

Answer 10

90 to 120 mmHg

Question 11

How is pulse pressure (PP)measured?

Answer 11

Systolic - diastolic pressure

Question 12

What id the formula for measure Mean arterial pressure? (MAP)

Answer 12

MAP = DBP + (1/3 of Pulse pressure)
DBP= diastolic blood pressure

Question 13

A person has SYSTOLIC pressure of 120 mmHg
DIASTOLIC pressure = 80 mmHg
What is Mean arterial pressure? (MAP)

Answer 13

MAp = DBP + (1/3 x PP)
DBP = 80
PP= SBP - DBP = 120 - 80= 40
MAP = 80 +(1/3 x 40)
MAP = 80 + 13’=
MAP = 93 mmHg

Question 14

Do SA node need input from the brain?

Answer 14

NOOOOOOOOOOOOOOO

Question 15

Electrical event in the heart in details?

Answer 15

• SA node = automatically depolarize initiating heart beat
• AV node= impulse arrive at AV node
  AV node DELAYS impulse allowing ATRIAL contraction fisrt
• Bundle of His = rapidly conducts to vanrticular Myocardium thorugh purnkinjee fibres for COORDINATED ventricular contaction
• Ventricular myocardium

Question 16

What does an Electrocardiogram do? (ECG)

Answer 16

detects electrical activity across heart

Question 17

What is P-wave produced by ECG?

Answer 17

• Atrial DEPOLARAZARION which leads to contraction

Question 18

What happens in the QRS complex in the ECG? (2)

Answer 18

• Ventricular depolarization - Ventricular contraction
• Atrial repolarisation - atria relax

Question 19

What is T-wave in ECG?

Answer 19

Ventricular repolarasation- relaxation