Physiology

Question 1

intrinsic control of SV

Answer 1

changes brought about by changes in diastolic length/ diastolic stretch of myocardial fibres

Question 2

EDV

Answer 2

volume of blood within each ventricle at the end of diastole

determines the cardiac preload

Question 3

cardiac afterload

Answer 3

the resistance into which the heart is pumping

Question 4

increase in afterload

Answer 4

at first: heart unable to eject full SV, so SV decreases > increase in EDV > force of contraction increase
eventually causing ventricular hypertrophy

Question 5

hormones that regulate extracellular fluid volume

Answer 5

the renin-angiotensin aldosterone system
natriuetic peptides
antidiuretic hormones

Question 6

rate liming step for RAAS

Answer 6

Renin secretion

RAAS regulated by mechanisms which stimulates renin release from juxtaglomerular apparatus in kidneys

Question 7

Juxtaglomerular apparatus

Answer 7

region comprising of the macula densa, extraglomerylar mesangial cells and granular cells

Question 8

Natriuretic peptides

Answer 8

peptide hormones synthesised by the heart and released in response to cardiac distension or stimuli

Question 9

NPs function

Answer 9

Cause excretion of salt and water in kidneys > reducing blood volume and BP

Question 10

decrease renin release =

Answer 10

decrease BP

Question 11

two types of NPs released by the heart

Answer 11

atrial peptide

brain-type natriuretic peptide

Question 12

shock

Answer 12

an abnormality of the circulatory system resulting in inadequate tissue perfusion and oxygenation

Question 13

causes of shock

Answer 13

loss of blood
sudden severe impairment of heart function
physical obstruction to circulation
excessive vasodilation and abnormal distribution of blood flow

Question 14

4 types of shock

Answer 14

hypovolaemic shock
cardiogenic shock
obstructive shock
distributive shock

Question 15

hypovolaemic shock

Answer 15

caused by loss of blood volume

haemorrhagic or non-haemorrhagic

Question 16

cardiogenic shock

Answer 16

caused by sudden severe impairment of cardiac function

Question 17

obstructive shock

Answer 17

caused by physical obstruction to circulation either in or out the heart
- PE, pneumothorax

Question 18

Distributive shock

Answer 18

caused by excessive vasodilation and abnormal distribution of blood flow
neurogenic or vasoactive

Question 19

Systemic vascular resistance

Answer 19

sum of resistance of all vasculature in the systemic circulation

Question 20

Resistance to blood flow

Answer 20

characteristics of blood, length of blood vessel, radius of blood vessel (inversely proportional to the power of 4)

Question 21

nerve control of vascular smooth muscle

Answer 21

sympathetic nerves
noradrenaline acting on alpha receptors
- constrict

Question 22

Vasomotor tone

Answer 22

means the vascular smooth muscle is partially constricted at rest
caused by tonic discharge of sympathetic nerves > continuous release of noradrenaline

Question 23

Main hormone control of vascular smooth muscle

Answer 23

Adrenaline from the medulla

• acting on alpha (skin, gut, kidney arterioles) receptors causes vasoconstriction
• acting on beta2 (cardiac and skeletal) receptors causes vasodilatation

Question 24

other hormones involved in control of vascular smooth muscle

Answer 24

angiotensin II- causes vasoconstriction

antidiuretic hormone- causes vasoconstriction

Question 25

intrinsic control of vascular smooth muscles

Answer 25

match the blood flow of different tissues to their metabolic needs can over-ride extrinsic controls chemical and physical factors

Question 26

chemical local metabolite factors causing relaxation of arteriolar smooth muscle

Answer 26

decreased PO2 | increased PCO2

Question 27

examples of chemical local humoral agents that cause vasodilation

Answer 27

histamine bradykinin NO

Question 28

Nitric oxide

Answer 28

continuously produced by vascular endothelium from amino acid L-arginine through enzymatic action of nitric oxide synthase potent vasodilator

Question 29

examples of chemical local humoral agents that cause vasoconstriction

Answer 29

serotinin thromboxane A2 leukotrienes endothelin- potent vasoconstrictor, released from endothelial cells

Question 30

factors influencing venous return

Answer 30

increased venomotor tone increased blood volume increased "skeletal muscle pump" increased "respiratory pump"

Question 31

Venomotor tone

Answer 31

increased venomotor tone increases venous return

Question 32

what is an ECG

Answer 32

recording of potential changes, detected by electrodes that allow the electrical activity of the heart to be monitored

Question 33

12 leads of the ECG

Answer 33

3 standard limb leadds 3 augmented voltage leads 6 chest leads- horizontal

Question 34

Lead II

Answer 34

sees the heart from inferior view

Question 35

PR interval

Answer 35

time for the SA node impulses to reach the ventricles

Question 36

Leads I and aVL

Answer 36

lateral leads | views the heart from the left

Question 37

Leads II, III, and aVF

Answer 37

inferior leads

Question 38

V1 and V2

Answer 38

coming from right | look at interventricular septum

Question 39

V3 and V4

Answer 39

lateral aspect

Question 40

3 types of syncope

Answer 40

reflex syncope orthostatic hypotension cardiac syncope

Question 41

physiological role of troponin I

Answer 41

binds to actin to hold the troponin-tropomyosin complex in place