Physiology

Question 1

Define ‘homeostasis’…

Answer 1

Maintenance of steady states within our bodies by coordinated physiological mechanisms

Question 2

Main type of homeostatic control in the body…

Answer 2

Negative feedback

Question 3

What are the components of a phospholipid?

Answer 3

Hydrophobic tail + hydrophilic head

Question 4

Bonds between phospholipids are strong. True/False?

Answer 4

False

Bonds are weak - explains the fluid nature of the membrane

Question 5

Cholesterol contributes to which two aspects of the membrane?

Answer 5

Fluidity and stability

Question 6

What are the 3 main types of proteins found on the membrane?

Answer 6

Integral (receptors)
Transmembrane (channels, transporters)
Peripheral (enzymes)

Question 7

The glycocalyx layer is formed by…

Answer 7

Short carbohydrate chains bound to proteins and lipids

Question 8

What are desmosomes?

Answer 8

Adhering junctions that anchor cells together

Question 9

What are tight junctions?

Answer 9

Join lateral edges of epithelial cells near their apical membranes

Question 10

What are gap junctions?

Answer 10

Communicating junctions that allow movement of charge between adjacent cells

Question 11

2 main factors that influence whether a particle can passively permeate the membrane

Answer 11

Lipid solubility (non-polar pass easily) 
Size

Question 12

Diffusion is movement from ___ to ___ concn

Answer 12

High to low

Question 13

Fick’s law of diffusion describes the rate of net diffusion and is made up of…

Answer 13

Magnitude of concn gradient
SA available for diffusion
Lipid solubility and size/weight of substance
Distance over which diffusion must occur

Question 14

Osmolarity is defined as…

Answer 14

The number of osmotically active particles present in a solution

Question 15

How is osmolarity calculated?

Answer 15

Using molar concn (mM) and number of osmotically active particles (n)

Question 16

150mM NaCl has osmolarity = ?

Answer 16

150 x 2 (Na+ and Cl-) = 300mOsm

Question 17

A hypotonic solution will ____ in cell volume
A hypertonic solution will ____ in cell volume
A isotonic solution will ____ in cell volume

Answer 17

Increase (needs mOre water)
Decrease (needs lEss water)
Have no change

Question 18

Facilitated diffusion requires energy. True/False?

Answer 18

False

Question 19

Active transport transfers a substance from high to low concn. True/False?

Answer 19

False

Low to high

Question 20

_ Na+ out for every _ K+ in with regards to Na-K pump

Answer 20

3, 2

Question 21

Secondary active transport occurs by which 2 mechanisms? Define them

Primary active transport uses…

Answer 21

Utilises conc. gradient and ion movement:
Symport (co-transport): solute and ion move in same direction
Antiport: solute and ion move in opposite directions

ATP directly for energy

Question 22

Membrane potential (Em) arises due to…

Answer 22

Separation of opposite charges across the membrane

Question 23

At resting potential, the membrane is 100x more permeable to sodium than potassium. True/False?

Answer 23

False 100x more permeable to K+ than Na+

Question 24

Em for K+ is approx…

Answer 24

-90mV

Question 25

Em for Na+ is approx...

Answer 25

+60mV

Question 26

Nernst equation

Answer 26

Eion = 61log[ion]o / [ion]i | extracellular/intracellular conc.

Question 27

Membrane potential is much closer to the potential of Na+ ions. True/False?

Answer 27

False | Much closer to Ek+ due to greater permeablity of K+

Question 28

Em for a typical nerve cell at rest = ?

Answer 28

-70mV

Question 29

GHK equation (used to calculate membrane resting potential)

Answer 29

Em = 61log x PK+[K+]o + PNa+[Na+]o / | PK+[K+]i + PNa+[Na+]i

Question 30

Normal blood glucose level

Answer 30

Around 5 mmol/l

Question 31

In the absorptive + post-absorptive states, which hormones control [glucose]p

Answer 31

Insulin and glucagon

Question 32

In emergencies, which hormone control [glucose]p | What is it released by?

Answer 32

Adrenaline | Released by adrenal gland

Question 33

In starvation, which hormones control [glucose]p | What are they released by?

Answer 33

Cortisol - Released by adrenal gland, | GH - Released by anterior lobe of the pituitary

Question 34

In pancreatic islet cells, _ cells release glucagon, _ cells release insulin and _ cells release somatostatin

Answer 34

alpha, beta, delta

Question 35

Insulin lowers [glucose]p by...

Answer 35

Stimulating uptake of glucose by muscle and fat cells Activating liver enzymes to convert glucose into glycogen HARMONE OF FED STATE

Question 36

Diabetics can increase GLUT4 expression by doing what?

Answer 36

Exercising

Question 37

Glucagon increases [glucose]p by...

Answer 37

Increasing glycogenolysis/inhibiting glycogen synthesis | HARMONE OF HUNGRY STATE

Question 38

Cortisol increases [glucose]p by...

Answer 38

Stimulating protein catabolism, lypolysis and gluconeogenesis

Question 39

Which receptors control mean arterial BP? Where are the receptors, control centre + effectors located?

Answer 39

Baroreceptors, located in aortic arch + carotid sinus Control centre: CN IX + X to medulla oblongata Effectors: heart + blood vessels

Question 40

Normal range for MAP?

Answer 40

Average arterial BP during single cardiac cycle | 70-105 mmHg

Question 41

Formulae for calculating MAP?

Answer 41

``` MAP = [(2x diastolic) + systolic]/3 MAP = diastolic + [systolic - diastolic]/3 MAP = CO x TPR ```

Question 42

MAP of at least __ mmHg is needed to perfuse coronary arteries, brain and kidneys

Answer 42

60 mmHg

Question 43

Firing rate in baroreceptors ____ when MAP increases

Answer 43

Increases (sensitive to stretch: when you stretch them, firing increases)

Question 44

What is meant by BP, systolic and diastolic?

Answer 44

Outwards hydrostatic pressure exerted by blood on BV walls - when heart contracts - when heart relaxes

Question 45

Normal arterial BP

Answer 45

<140 systolic, <90 diastolic

Question 46

Cardiac output (CO) is...

Answer 46

The volume of blood pumped out by each ventricle per minute (SV x HR)

Question 47

Stroke Volume (SV) is...

Answer 47

Volume of blood pumped out by each ventricle per heart beat

Question 48

Increasing contractile strength of the heart causes stroke volume to ____

Answer 48

Increase

Question 49

What is meant by 'autorhythmicity'?

Answer 49

Heart can beat rhythmically in abscence of external stimuli

Question 50

Influence of sympathetic and parasympathetic systems on HR and force of contraction...

Answer 50

Increase - NR on B1 receptors, Increase | Decrease - Ach on M receptors, No effect

Question 51

Main resistance vessels are...

Answer 51

Arterioles

Question 52

What is 'total peripheral resistance' and what is it controlled by?

Answer 52

Sum of all resistance of all peripheral vasculature in systemic circulation Vascular SM especially arterioles - vasoconstriction (increase), vasodilatation (decrease)

Question 53

Vasomotor tone is described as... | Caused by?

Answer 53

Vascular smooth muscle being constricted at rest | Tonic discharge of sympathetic nerves

Question 54

Core body temperature is about...

Answer 54

37.8'C

Question 55

Basal metabolic rate is defined as...

Answer 55

The minimum amount of energy required to sustain body functions

Question 56

Which receptors monitor body heat? Where are they, the control centre and effectors located?

Answer 56

Thermoreceptors, located in the hypothalamus (CORE TEMP) and skin (PERIPHERAL TEMP) Control centre: hypothalamus Effectors: skeletal muscles, skin arterioles, sweat glands

Question 57

Mechanisms of heat gain...

Answer 57

Radiation Convection Conduction

Question 58

Mechanisms of heat loss...

Answer 58

Radiation Convection Conduction Evaporation

Question 59

What contributes to half of total heat loss in the body?

Answer 59

Radiation - emission of energy as electromagnetic waves from a surface

Question 60

What term is used to describe 'transfer of heat between objects in contact'?

Answer 60

Conduction

Question 61

What is convection?

Answer 61

Transfer of heat energy by air/water currents that carry heat away from the body

Question 62

What term is used to describe 'the energy required to convert water in skin/ respiratory tract into vapour'

Answer 62

Evaporation

Question 63

What is the body's temperature control centre? What parts are activated by the cold and warmth?

Answer 63

Hypothalamus Cold = Posterior Warmth = Anterior

Question 64

Fever is temperature between...

Answer 64

38-40'C

Question 65

Hyperthermia is temperature...

Answer 65

> 40'C

Question 66

Hypothermia is temperature below...

Answer 66

35'C