Physiology

Question 1

Mean arterial pressure

Answer 1

MAP = SBP + (2DBP) / 3
or DBP + (PP/3)

Question 2

Stroke Volume

Answer 2

Blood volume ejected during systole
LVEDP - LVESP

Question 3

Preload

Answer 3

The stretch or wall tension applied to the ventricle by ventricular filling just prior to onset of systole

Question 4

Afterload

Answer 4

Ventricular wall tension during systole that overcomes impediments to ventricular ejection

Question 5

Contractility

Answer 5

Intrinsic ability for cardiac myocyte to do work at a given preload and after load

Question 6

LaPlace’s Law

Answer 6

Wall tension = pressure x radius / (2x wall thickness)
(for LV afterload)

Pressure = surface tension / radius
(for alveoli - as radius decreases, pressure increases, so surface tension must be reduced to prevent collapse of the small alveoli)

Question 7

Mean systemic filling pressure

Answer 7

the pressure that would be measured at all points in the entire circulatory system if the heart were stopped suddenly and the blood were redistributed instantaneously in such a manner that all pressures were equal.

Question 8

Systemic vascular resistance

Answer 8

resistance to flow in the systemic circulation against LV during systole

Question 9

Dyne

Answer 9

force that will give a mass of 1g an acceleration of 1cm s^-2

Question 10

Valsalva manoeuvre

Answer 10

forceful exhalation against a closed glottis for a period of 10-20s, with various BP / HR responses

Question 11

Acid

Answer 11

Proton donor
Strength of acid depends on its tendency to donate a proton

Question 12

Base

Answer 12

Proton acceptor

Question 13

pH

Answer 13

negative log 10 of [H+]

Question 14

[H+] at pH 7.4

Answer 14

40nmol / L

Question 15

pKa

Answer 15

pH at which there are equal parts of ionised and unionised molecules of a drug

Question 16

Buffer

Answer 16

A substance, typically a weak acid, which resists change of pH in a given solution when stronger acid/base are added

Question 17

Isohydric principle

Answer 17

All buffering systems in the body are in equilibrium.
Changes to one system will affect all other systems

Question 18

Resting membrane potential

Answer 18

The potential difference present across the cell membrane when no stimulation is occurring

Question 19

Action potential

Answer 19

spontaneous depolarisation of an excitable cell in response to a stimulus

Question 20

Gibbs-Donnan Effect

Answer 20

behaviour of charged particles near a semi-permeable membrane that don’t distribute evenly due to the presence of negatively charged proteins

Question 21

How much bile per day

Answer 21

1L, which gets concentrated to 1/5 of volume

Question 22

Constituents of bile

Answer 22

water, electrolyte, bile salt,

Question 23

Structure and function of bile salts

Answer 23

amphipathic
surround dietary lipid, break into small fat droplets -> formation of micelles