Cardiovascular System

Question 1

Layout

- pathways, capillary beds, system

Answer 1

1. RV -> Pulmonary artery -> lungs (deoxy)
2. LV -> aorta -> tissue (oxy)
3. Capillary beds arranged mainly in parallel
4. Portal system

Question 2

Hepatic system as an example

Answer 2

1. Each capillary bed receives arterial blood from LV

2. Flow to different capillary beds altered selectively, determined by resistance

Question 3

Cross-sectional area is greatest at

Answer 3

Capillary level

Question 4

How do arteries respond to pressure?

Answer 4

Dampen pressure variations by pulsatile action

Question 5

Largest proportional pressure drop in

Answer 5

Arterioles -> max resistance to flow

Question 6

MABP =

Answer 6

Diastolic pressure + 1/3 Pulse pressure

Question 7

PP =

Answer 7

(systolic - diastolic) pressures

Question 8

1kpa = X mmHg = Y cmH2O

Answer 8

7.5, 10.2

Question 9

Q =

Answer 9

V x a ( velocity x cross-sec area)

Question 10

Systemic pressure =

Answer 10

deltaP = MABP - Right arterial pressure

Question 11

Pulmonary pressure

Answer 11

deltaP = MpABP - LAP

Question 12

Resistance =

Answer 12

delta P/ Q (flow)

Question 13

Poiseuile’s Law

Answer 13

Q = deltaP / R = deltaPxpix r* / 8nl

where n = viscosity and l = length of vessel

Question 14

nrel1 =

Answer 14

water

Question 15

nrel3 =

Answer 15

blood

Question 16

Ht of plasma

Answer 16

nrel = 1.5

Question 17

Factors which affect viscosity

Answer 17

1. Ht
2. Hypoxia - main factor
3. Sickle cell

Question 18

P wave represents

Answer 18

Atrial dep.

Question 19

QRS complex represents

Answer 19

Vein dep.

Question 20

T wave represents

Answer 20

Vein rep.

Question 21

ECG timings

Answer 21

1. P-R: 0.12-0.2 s
2. QRS: 0.08s
3. QT: 0.25-0.4s

Question 22

Why does ST have no net flow?

Answer 22

Isoelectric region

Question 23

Outline stages of the cardiac cycle

Answer 23

1. At beginning ventricular contractionm mital valve closes until a.p. = v.p.
2. At beg. relaxation, atrial valve closes + v.p. falls to = a.p.
3. Heart sounds at beg. + end of v. contraction
4. Vein changes to mirror atrium changes

Question 24

Cardiac output =

Answer 24

S.V. x H.R.

Question 25

Factors that affect cardiac output

Answer 25

1. H.R. 2. Mycocardial contractility 3. Preload 4. Afterload

Question 26

Starling's law

Answer 26

1. Input to heart + output from ventricle = | 2. Output of RV + LV are equal

Question 27

+ve _____ effect when sympathetic stimulation increases _______

Answer 27

Ionotropic, cardiac

Question 28

Kidney's role in arterial b.p.

Answer 28

Reabsorption of NA+ to decrease preload

Question 29

Where are baroreceptors located?

Answer 29

Peripherally located in neck -> at division of common carotid artery into external/ internal branches

Question 30

In barareceptor reflex : mean a.p. - RAP =

Answer 30

Co x total peripheral R

Question 31

Afferent :

Answer 31

Carotid sinus > sinus nerve > glossopharyngeal nerve

Question 32

Efferent:

Answer 32

ANS -> SAN, myocardium, vascular smooth muscle

Question 33

Renin-angiotensin system

Answer 33

Regulation of aldosterone increase by adrenal cortex + atria release ANP -> natriuresis (secretion of sodium in urine)

Question 34

Intrinsic regulation of blood flow through tissues

Answer 34

Increase blood flow regulated by vasodilatery effect -> route of waste product generation

Question 35

Extrinsic regulation of blood flow through tissues

Answer 35

1. N/S hormones 2. NA (p-G NT) acts on alpha receptors on vascular sm. -> vasoc. 3. Alpha regulated beds have reduced blood flow when body attempts to restore b.p. by increasing total peripheral R so blood redirected to vital oragns 4. Some capillary beds 5. A/NA -> +ve ionotropic effect (cardiac contraction) , +ve chronotropic (tachycardia) 6. Autoregulation in cerebral + renal circulations

Question 36

Cerebral circulation

Answer 36

1. Dual arterial input : posteriar com. arteries -> carotid and basilar arteries 2. uR: around 20% resting O2 conc, RQ around 1.0 3. Autoregulation : 60-200mmHg - > principally regulated by local CO2 gas tensions

Question 37

Coronary circulation

Answer 37

1. O2 extraction by myocardial tissue is efficient 2. Symp. stimulation to increase coronary blood flow 3. Flow during systole is low : after ventricular relaxation

Question 38

Cutaneous circulation

Answer 38

1. Nutrient blood to tissues, extrinsic vascular control -> temp reg. + protection 2. Orterio-venous anastamosus to increase autoneus blood flow

Question 39

What is the triple response to trauma?

Answer 39

1. Red - capillary dilation 2. Wheal - Capillary becomes more permeable to proteins 3. Flare -> dilation of local blood vessels to local sensory fibres branched nearby

Question 40

Preload

Answer 40

Volume of blood in ventricles at end of diastole

Question 41

Afterload

Answer 41

Resistance left ventricle must overcome to circulate blood