Understanding the physiology of the cardiovascular system

Question 1

what are the components of the cardiovascular system

Answer 1

• cardiopulmonary unit
• left and right side
• pulmonary artery and vein
• arteries, arterioles, capillaries, venules and veins
• portal systems
• intra-renal circulation
• intra-coronary circulation
• intra-cranial circulation

Question 2

what are portal systems. give examples

Answer 2

an arrangement by which deoxygenated blood collected from are from a set of capillaries passess through a large vessel or vessels to another set of capillaries before it returns to the systemic circulation
e.g., -> hepatic portal system -> hypothalamic + anterior pituitary (hypophyseal)

Question 3

hypophyseal

Answer 3

hypothalmic and anterior pituitary portal system

Question 4

stroke volume

Answer 4

the volume of blood pumper by the left ventricle per beat. denoted by SV

Question 5

cardiac output

Answer 5

the volume of blood pumped by the heart per unit time. measured as L/min and denoted by Q

Question 6

perfusion

Answer 6

the passage of blood through the circulatory system to the body’s tissues. measured as ml of blood/min/g of tissue

Question 7

preload

Answer 7

the degree to which the left ventricle is filled at the end of diastole, just prior to systolic contraction. measured as mL and denoted as EDV

Question 8

contracticity

Answer 8

the innate ability of the myocardium to contract

Question 9

afterload

Answer 9

the resistance against which the L ventricle must eject the SV from the heart. measured as aortic pressure during systole divided by cardiac output

Question 10

compliance

Answer 10

the ability of the blood vessel to expand and contract with changes in pressure. measured as unit of volume change per unit of pressure change. denoted by C

Question 11

functions of the cardiovascular system

Answer 11

1. rapid connective transport of O2, glucose, amino acids + fatty acids, vitamins, water, waste products of metabolism, i.e., CO2, urea, creatinine.
2. homeostatic control- hormones and temperature

Question 12

factors that affect heart rate

Answer 12

atrial reflex, autonomic innervation, hormones

Question 13

atrial reflex

Answer 13

The Bainbridge reflex (aka, atrial reflex) occurs when the heart rate increases in response to a rise in atrial pressure. This is a compensatory mechanism since increased right atrial pressures frequently result from elevated left heart pressures from decreased cardiac output.

Question 14

factors that affect stroke volume

Answer 14

venous return, filling time, autonomic innervation, hormones, vasodilation/vasoconstriction

Question 15

what factors affect preload

Answer 15

venous return, filling time

Question 16

what factors affect contractility

Answer 16

autonomic innervation and hormones

Question 17

what factor affects afterload

Answer 17

vasodilation/vasoconstriction

Question 18

factor that affects end diastolic volume

Answer 18

preload

Question 19

factors that affect end systolic volume

Answer 19

preload, contractility and afterload

Question 20

stroke volume formula

Answer 20

EDV-ESV

Question 21

formula for Q

Answer 21

HR x SV

Question 22

define frank-starling mechanism

Answer 22

the SV of the heart increase in response to an increase in the vol of blood in the ventricles before contraction when all other factors remain constant

Question 23

what do each of the four corners on the frank-starling graph stand for

Answer 23

1. mitral valve closes
2. Aortic valve opens
3. Aortic Valve closes
4. Mitral Valve closes

Question 24

an increase in preload, afterload or contractility would lead to an ____ in EDV, _____ in ESV and ____ in stroke volume

Answer 24

1. increase
2. decrease
3. increase

Question 25

a decrase in preload, afterload or contractility would lead to an ____ in EDV, _____ in ESV and ____ in stroke volume

Answer 25

1. decrease 2. increase 3. decrease

Question 26

what are the two main extrinsic controls of circulation

Answer 26

1. autonomic: sympathetic and parasympathetic | 2. RAAS System

Question 27

where are the parasympathetic control centres/nerves locate

Answer 27

brain stem, cranial nerves, sacral outflow, end organ ganglia, postganglionic (ACh + adrenergic, non-cholinergic (NANC) transmitters)

Question 28

where are the sympathetic control centres/nerves located

Answer 28

brain stem, spinal cord, preganglionic fibres (ACh), spinal ganglia, postganglionic fibres (NA), distant ganglial (coeliac + hypogastric ganglia and the adrenal medulla)

Question 29

sympathetic stimulation of the blood vessels would lead to ....

Answer 29

vasoconstriction

Question 30

ionotropy

Answer 30

contractility

Question 31

chronotropy

Answer 31

heart rate

Question 32

dromotropy

Answer 32

velocity of the AV node

Question 33

agonism of a1 , a2 and b1 receptors would ______ iontropy, chronotopy and dromotropy and cause _______

Answer 33

increase, vasoconstriction

Question 34

agonism of b2 receptors would _______ ionotropy, chornotropy and dromotropy and cause ________

Answer 34

decrease, vasodilation

Question 35

when is RAAS system triggered

Answer 35

drop in blood pressure or blood volume

Question 36

RAAS mechanism

Answer 36

1. angiotensin is released by the liver 2. renin produced by the kidney acts on the angiotensin and forms angiotensin I 3. ACE is released by the lungs+ kidneys that converts angiotensin I to angiotensin II 4. Angiotensin II acts on the adrenal gland to release aldosterone 5. Aldosterone acts on the kidneys to stimulate reabsorption of NaCl and H2O. 6. Angiotensin II also acts on the blood vessels and stimulates vasoconstriction

Question 37

what cells produce renin

Answer 37

juxtaglomerular cells in the afferent arteriole of the renal glomerulus.

Question 38

what stimulates the production of renin by the kidneys

Answer 38

1. sympathetic nerve activation (acting via the b1 receptor) 2. renal artery hypotension (caused by systemic hypotension or renal artery stenosis) 3. decreased sodium delivery to the distal tubules of the kidney sensed by the cells in the Macula Densa

Question 39

what cells produce ACE and what is it's purpose

Answer 39

vascular endothelium, especially in the lungs contain ACE and that cleaves Ang-I to Ang-II

Question 40

what are the two receptors that Ang-II acts on

Answer 40

T1 receptors- vasoconstriction, cell proflieration, inflammatory responses, blood coagulation, extracellular matrix remodelling T2 receptors counteract these effects

Question 41

actions of Ang-II on the CVS

Answer 41

1. constricts resistance vessels thereby increase SVR and arterial pressure 2. stimulates sodium transport (reabsorption) at several renal tubular sites, thereby increasing sodium and water retention 3. acts on the adrenal cortex to release aldosterone 4. stimulates thirst 5. facilitates noradrenaline release from sympathetic nerve endings and inhibits it reuptake 6. stimulates cardiac hypertrophy and vascular hypertrophy

Question 42

actions of aldosterone on the CVS

Answer 42

1. affects the final part of electrolyte and water absorption within the nephron before acretion in the urine 2. increases the amt of sodium reabsorbed from the distal tubule and collecting duct of the kidney

Question 43

actions of adrenaline on the CVS

Answer 43

stimulates all major receptors- a1, a2, b1, b2. at low concentrations in b2 selective, it causes vasodilation and at higher concentrations, it stimulates the other adrenergic receptors causing vasoconstriction and this increases heart rate and contractility. also causes renal arterioles vasoconstriction, reducing blood flow to the glomeruli and nephrons

Question 44

when is Antidiuretic hormone or Arginine vasopressin released

Answer 44

during hypovolaemic shock

Question 45

where is Antidiuretic hormone or Arginine vasopressin synthesised

Answer 45

hypothalamus and released from the posterior pituitary gland

Question 46

what is Antidiuretic hormone or Arginine vasopressin released in response to

Answer 46

reduction in plasma volume, and an increase in plasma osmolarity

Question 47

ADH affect on CVS

Answer 47

acts via V1 receptors to cause arteriolar constriction

Question 48

ADH affect on kidney

Answer 48

acts via V2 receptors to cause increase in the amt of water reabsoprtion by renal tubules

Question 49

natriuretic peptide

Answer 49

produced, stored and released by atrial myocytes due to atrial distention. acts in response to high renal Na+ excretion and in response to increased stretching of the atrial blood volume.`

Question 50

two kinds of natriuretic peptides produced by the heart

Answer 50

BNP, ANP