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Flashcards in Physiology Deck (88)
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1
Q

what is the hydrophilic bilayer composed of

A
  • hydrophilic heads

- hydrophobic tails

2
Q

what is the role of cholesterol in the cell membrane

A
  • contributes to fluidity and stability

- stiffens membrane

3
Q

what are the 3 possible locations of proteins in/around cell membrane

A
  • integral (embedded within)
  • peripheral (don’t penetrate membrane)
  • transmembrane (extend through membrane)
4
Q

what is the location of carbohydrates in relation to the cell membrane and what types are there

A
  • small amount located on outer surface

- glycoproteins, glycolipids

5
Q

what are the 3 functions of the lipid bilayer

A
  • basic structure of membrane
  • hydrophobic interior acts as barrier
  • responsible for membrane fluidity
6
Q

The glycocalyx layer is formed by…

A

Short carbohydrate chains bound to proteins and lipids

7
Q

what are the main functions of proteins

A
  • water filled, selective ion channels
  • carrier/transport proteins
  • docking/marker acceptors
  • receptors or enzymes
  • cell adhesion molecules
8
Q

what are the 2 types of cell adhesion molecules

A
  • Cadherins (hold cells within tissues together)

- Integrins (span membrane to link intra and extracellular environments)

9
Q

what are occlusion/tight junctions

A

join neighbouring cells together to prevent diffusion

10
Q

what are anchoring/desmosome junctions

A

they provide mechanical support, anchor cells together

11
Q

what are communicating/gap junctions

A

they create pores to allow the movement of molecules between 2 cells

12
Q

what are the 2 types of passive transport

A
  • diffusion

- electrical gradient

13
Q

during passive transport where do cations move to

A

cations move towards -vely charged areas

14
Q

what does Fick’s Law of diffusion relate to

A
  • size of concentration gradient
  • surface area of membrane
  • lipid solubility
  • molecular weight
  • distance for diffusion
15
Q

what is an electrochemical gradient

A

Where an electrical and a chemical concentration gradient may be acting on a particular ion at the same time

16
Q

define osmosis

A
  • Net diffusion of water down its concentration gradient
  • conc. of osmotically active particles in a solution
  • aquaporins are water channels
17
Q

how is osmolarity calculated

A

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

18
Q

150mM NaCl has osmolarity = ?

A

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

19
Q

define tonicity

A

effect a solution has on cell volume

20
Q

what effect does a hypotonic solution have on cell volume

A

increases cell volume

21
Q

what effect does a hypertonic solution have on cell volume

A

decreases cell volume

22
Q

what happens during carrier-mediated transport

A

substance binds to specific carrier and changes its conformation to transport it

23
Q

what effects carrier-mediated transport

A
  • specificity
  • saturation
  • competition
24
Q

what is facilitated diffusion

A
  • no energy required
  • carrier-mediated
  • from high to low conc.
25
Q

what is active transport

A
  • energy required

- from low to high conc.

26
Q

what is primary active transport

A

energy directly required

27
Q

what is secondary active transport

A
  • energy required but not used directly

- energy stored in form of ION CONC. GRADIENT (usually Na+)

28
Q

what are the mechanisms of secondary active transport

A
  • symport (same direction)

- antiport (opposite direction)

29
Q

what is vesicular transport

A
  • energy for vesicle formation

- endocytosis or exocytosis

30
Q

what type of active transport is is NaKATPase pump

A
  • primary active transport
31
Q

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

A

3, 2

32
Q

3 roles of NAKATPase pump

A
  • Establish Na and K concentration gradients across
  • regulate cell volume
  • energy source
33
Q

what is the membrane potential (Em)

A
  • separation of charges across membrane

- units are mV

34
Q

what are the direction of Na and K ion movements

A
  • K moves outwards

- Na moves inwards

35
Q

at resting potential the membrane is 100x more permeable to what

A

more permeable to K than Na

36
Q

describe movement of K+ ions

A
  • K+ move down con gradient out of cell
  • still negative anions inside cell
  • results in electrical gradient moving K+ back into cell
37
Q

describe movement of Na+ ions

A
  • Na+ move down conc gradient into cell
  • still negative anions outside cell
  • results in electrical gradient moving Na+ out of cell
38
Q

what is the membrane potential of Ek

A

-90mV

39
Q

what is the membrane potential of Ena

A

+61mV

40
Q

what does the Nernst equation calculate

A

membrane potential of a single ion

41
Q

what does the Goldman - Hodgkin - Katz equation calculate

A

overall membrane potential

42
Q

what is the resting membrane potential of a typical nerve cell

A
  • 70mV
43
Q

is the resting membrane potential nearer to Ek or Ena

A
  • Ek

- not exactly the same due to slight inward leak of Na

44
Q

Na channels are…

K channels are….

A
Na = depolarisation 
K = repolarisation
45
Q

define action potentials

A

brief electrical signals in which the membrane polarity is momentarily reversed
- spread along with constant size and velocity

46
Q

glucose is a…

A

metabolic fuel

47
Q

hormones controlling glucose in absorptive and post absorptive states are..

A

insulin and glucagon

pancreas

48
Q

hormones controlling glucose in emergencies are…

A

adrenaline

adrenal gland

49
Q

hormones controlling glucose in starvation are…

A

cortisol (adrenal) and growth hormone (pituitary gland)

50
Q

name the pancreatic islets of Langerhans (endocrine cells)

A
  • alpha cells = glucagon
  • beta cells = insulin
  • delta cells = somatostatin
51
Q

What are the absorptive states

A
  • increased glucose levels
  • insulin rises
  • glucagon falls
52
Q

what does insulin favour and what does it do

A
  • favours anabolism

- converts glucose > glycogen

53
Q

insulin is a hormone of what state

A

the fed state

54
Q

diabetes mellitus type 1 has what properties

A
  • early onset
  • no insulin secretion
  • defect in beta cells
  • insulin injections required
55
Q

diabetes mellitus type 2 has what properties

A
  • adult onset
  • insulin secretion may be normal
  • defect in insulin sensitivity
  • diet/exercise/oral drugs
56
Q

Diabetics can increase GLUT4 expression by doing what?

A

exercise

57
Q

the pulse pressure is the difference between what

A

systolic and diastolic BP’s

58
Q

what is the normal MAP range

A

70-105

59
Q

how do you calculate MAP

A
MAP = [(2x diastolic) + systolic]/3
MAP = diastolic + [systolic - diastolic]/3 
MAP = CO x SVR
60
Q

Which receptors control mean arterial BP and where are the receptors

A

Baroreceptors, located in aortic arch + carotid sinus

61
Q

what is the control centre used by baroceptosr and what are the effectors

A

control centre = medulla

effectors = heart and blood vessels

62
Q

MAP of at least __ is needed to perfuse heart, brain, kidneys

A

60mmHg

63
Q

MAP needs to be low enough so that it doesn’t…

A

damage blood vessels

64
Q

what happens to the firing rate in baroreceptors when MAP increases

A

firing rate also increases

65
Q

Cardiac Output is

A
  • The volume of blood pumped out by each ventricle per minute
  • (SV x HR)
66
Q

Stroke Volume is

A
  • the volume of blood pumped out by each ventricle per heart beat
67
Q

Increasing contractile strength of the heart causes stroke volume to ____

A

increase

68
Q

Vasomotor tone is described as what

A

Vascular smooth muscle being constricted at rest

69
Q

define homeostasis

A

maintenance of a stable internal environment

70
Q

to maintain homeostasis you must be able to do what

A
  • sense deviations from normal
  • integrate this information
  • make appropriate adjustments to restore variable
71
Q

what are intrinsic controls

A

within organ

72
Q

what are extrinsic controls

A
  • outside organ

- use nerves and hormones

73
Q

define feedforward

A

responses made in anticipation of change

74
Q

define feedback

A

responses made after change has occurred

75
Q

define negative feedback

A
  • opposes initial change

- eg controlling body temp.

76
Q

define positive feedback

A
  • amplifies initial change

- eg uterus contractions become stronger until birth

77
Q

what is the core body temperature

A

37.8 degrees

78
Q

what is normothermia

A

when body temperature varies during day (lowest in early morning)

79
Q

define basal metabolic rate

A

minimum energy required to sustain body functions

80
Q

how can the basal metabolic rate be increased

A
  • hormones eg adrenaline

- muscle activity/shivering

81
Q

what are the 4 methods of heat gain

A
  • metabolic heat
  • radiation
  • convection
  • conduction
82
Q

what are the 4 methods of heat loss

A
  • convection
  • conduction
  • radiation
  • evaporation
83
Q

pOsterior hypothalamus is activated by what

A

cOld

84
Q

Anterior hypothalamus is activated by what

A

wArmth

85
Q

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

A
  • Thermoreceptors
  • located in the hypothalamus and skin
  • Control centre: hypothalamus
  • Effectors: skeletal muscles, skin arterioles, sweat glands
86
Q

a fever is a temperature between what

A

38-40 degrees

87
Q

hyperthermia is a temperature between what

A

> 40 degrees

88
Q

hypothermia is a temperature between what

A

35 or below degrees