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principles of normal function > week 1 > Flashcards

week 1 Flashcards

1
Q

what is aetiology

A

causes of disease

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2
Q

what is pathogenesis

A

how disease develops

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3
Q

what are symptoms

A

what patients notice

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4
Q

what are signs

A

doctor’s observations

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5
Q

what is homeostasis

A

maintenance of a relatively constant internal environment

- maintain optimum ‘similar’ conditions

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6
Q

what can failure of homeostasis result in

A

pathology

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7
Q

what does homeostasis require

A

integration of organ systems

- this requires regulation at cell, tissue and system level

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8
Q

what are common everyday challenges to our internal environment

A
  • external temperature
  • cellular access to nutrients
  • exercise
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9
Q

what are the mechanisms to maintain homeostasis

A
  1. negative feedback (most important)
  2. feedforward
  3. positive feedback
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10
Q

what is negative feedback control

A

the condition that triggered the homeostatic response becomes switched off or removed by that response
e.g. person outside on hot day, loses body water by evaporation, body fluids become more concentrated, internal receptors sense change in internal concentration, thirst pathways stimulated and person seeks out and drinks water and body fluid concentration decreased

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11
Q

what are the characteristics of negative feedback control

A
  • there is oscillation around the set point

- restores the regulated condition after its intitial disturbance but cannot prevent it happening

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12
Q

what is a feed forward system

A

in feedforward control additional receptors permit system to anticipate change and therefore activate response earlier
e.g. man outside on hot day, body pre-empts that body fluid concentration may decrease and so conserves water by producing more smaller volumes of concentrated urine

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13
Q

what are positive feedback mechanisms

A
  • opposite effect of negative feedback
  • positive feedback sets off a train of events that lead to an even greater disturbance
  • common in pathology but rare in physiology
  • e.g. nerve action potential and sexual behaviour
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14
Q

what are the homoestatically regulated processes that maintain water balance

A
  • input is regulated by the thirst mechanism
  • output is regulated by kidney function
  • other processes that alter water balance are also regulated but their control is not aimed at maintaining water balance e.g. sweating
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15
Q

what are the compartments water is contained in in our bodies

A
  • intracellular fluid
  • interstitial fluid
  • plasma
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16
Q

what is the barrier that separates plasma and interstitial fluid

A

blood vessel capillary wall

- permeable to everything but plasma protein and blood cells

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17
Q

what is the barrier between interstitial fluid and intracellular fluid

A

cell membrane

- selectively permeable

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18
Q

how many litres of plasma does the average man have

A

3 litres

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19
Q

how many litres of interstitial fluid does the average man have

A

11 litres

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20
Q

how many litres of intracellular fluid does the average man have

A

28 litres

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21
Q

what is the total body water of the average man

A

42 litres

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22
Q

how man litres of extracellular fluid does the average man have

A

14 litres

plasma + ISF

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23
Q

what is the difference between plasma and interstitial fluid

A

plasma contains plasma proteins and and blood cells which are to large to get through capillary
- other than that composition is identical

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24
Q

what are the three things to remember about the dilution principle

A
  1. c=m/v, v=m/c : dilution principle
  2. only plasma can be samples (so only compartments of which plasma is a component can be sampled directly - plasma, ECF, total body water)
  3. the nature of the barriers which separate components is crucial in determining the test substance (e.g. really the only barrier between plasma and ISF is for proteins and blood cells)
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25
Q

what techniques do you use for dilution principle in plasma

A

since plasma proteins cannot cross capillary walls, can use dues or radioactive labels that attach to plasma proteins
e.g. Evan’s blue or I25 albumin

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26
Q

what techniques do you use for dilution principle in extracellular volume

A

need something that freely crosses capillary walls but cannot cross cell membrane e.g insulin, sucrose, mannitol or 24Na+, 36Cl- which are actively extruded from cells

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27
Q

what techniques do you use for dilution principle in total body water

A

there is no barrier to water in the body so can use a loading does of heavy water/deuterated water (D2O)

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28
Q

how to use dilution principle to calculate ISF and ICF

A 
ISF = ECF-PV 
ICF = TBW - ECF
29
Q

what is the method of practice of dilution principle

A
  1. inject a substance that will stay in one compartment only
  2. then calculate the volume of distribution = amount injected (minus any removed by excretion or metabolism) divided by the concentration in the sampled fluid
30
Q

example of dilution principle

A 
using sucrose which is restricted to ECF:
- 150mg of sucrose 
- [sucrose] blood sample after distribution = 0.01mg/ml
- 10mg were excreted or metabolised 
what is the volume of the ECF?
150mg-10mg = 140mg
v=m/c
  =140/0.01
  =14,000ml
31
Q

what are nucleoli

A

sites of ribosomal RNA synthesis and ribosomal assembly

32
Q

hydrogen bonding

A
  • HONC can make 1, 2, 3, 4 bonds respectively
33
Q

what are different functional groups

A

hydroxyl - OH
aldehyde - CH=O
keto -C=O

34
Q

what do functional groups do

A

define biomolecular function

35
Q

apart from functional groups what else determines bimolecular function

A

configuration

e. g. trans and cis
- carbon based molecules can be symmetrical (achiral) or asymmetrical (chiral)
- asymmetrical carbon molecules are described as being either L- or D-
- all proteins are made from L-amino acids only

36
Q

what are the five chemical reactions of life

A
  1. redox reactions
  2. making and breaking C-C bonds (e.g. glucose to pyruvate)
  3. internal rearrangements (rearrangement of the confirmation of G6P before sugar is split)
  4. group transfers
  5. condensation and hydrolysis
37
Q

what does NADH do

A

it is a reducing agent (which becomes oxidised itself to NAD+ as it reduces other compounds)

38
Q

what does NAD+ do

A

it is an oxidising agent (which itself becomes reduced as it oxidises other compounds)

39
Q

what is D-glucose

A

reducing sugar

40
Q

what kind of bases are pyrimidines

A

cytosine and thymine (and uracil)

41
Q

what kind of bases are purines

A

adenine and guanine

42
Q

what are fatty acids

A

long chains of carbon and hydrogen atoms form fatty acids

43
Q

if all the bonds in a fatty acid are single what is the fatty acid said to be

A

saturated

44
Q

if there is one double bond present in a fatty acid what is the fatty acid said to be

A

mono-unsaturated

45
Q

if there are more than one double bond in the fatty acid what is it said to be

A

polyunsaturated (the more double bonds the ‘bendier’ it is said to be and therefore the more fluid - e.g. oil is more fluid than lard)

46
Q

what are lipids

A

a family of molecules made up of fatty acids

47
Q

what are the three classes of lipids

A
  • triacylglycerides
  • phospholipids
  • sterols
48
Q

what are triacylglycerides

A
  • storage lipids
  • non-polar
  • 3 fatty acid chains linked to glycerol
49
Q

what are phospholipids

A
  • two fatty acid chains and a phosphate group attached to the ‘head’ of these chains
  • this makes them polar
  • they form biological cell membranes
50
Q

what are sterols

A
  • produced in plants, animals and some micro-organisms
  • most important one in humans is cholesterol (another essential component to cell membranes and precursor to steroid hormones and fat soluble vitamins (A,D,E))
51
Q

what are some examples of hydrophilic molecules

A

sugars, alcohols, aldehydes, ketones, compounds with N-H groups, charged particles such as ions (water forms a ‘screen’ around charged particles)

52
Q

what are some examples of hydrophobic molecules

A

fat soluble vitamins (A,D,E,K), lipids, cholesterol, steroid hormones, oxygen

53
Q

what are amphipathic molecules

A

contain both hydrophobic and hydrophilic parts e.g phospholipids

54
Q

what is a micelle

A

sphere of phospholipid with hydrophobic part orientated to the centre away from the water

  • amphipathic
  • core is filled with hydrophobic tails
55
Q

what are liposomes

A

if you put lots of phospholipids with water you get a sphere with a lipid bilayer outer shell and a hollow core

56
Q

what is a chylomicron

A

it is how lipid is transported in the blood

- it is a liposome with protein embedded in the shell and lipid stored in the core

57
Q

what does 1 pH unit represent

A

a ten-fold increase or decrease in [H+]

58
Q

what are strong acids and strong bases

A

they fully dissociate

59
Q

what do weak acids do

A
  • they only partially dissociate
  • this gives them the ability to act as ‘buffers’
  • optimal pH is maintained by using weak acids and their bases as buffers
60
Q

what buffer system is important in cells

A

the phosphate buffer system

61
Q

what buffer system is important in plasma

A

the bicarbonate buffer system

62
Q

what is the Henderson hasselbalch equation

A

pH is proportional to the ratio of buffer to H-buffer

the more buffer you have the more the pH goes up and the more H-buffer you have the more pH goes down

63
Q

what is the first law of thermodynamics

A

energy can be converted from one form to another but the total energy of the universe remains constant

64
Q

what is the second law of thermodynamics

A

all energy transformations ultimately lead to more disorder in the universe i.e. increase the energy
- as usable energy decreases and unusable energy increases entropy increases

65
Q

what is Gibbs free energy

A

‘useful’ or free energy in a closed system
G=H-TS
(H - enthalpy=heat released to surroundings)
(S=entropy)
(T = absolute temperature)

66
Q

how can you tell a reaction is spontaneous

A

has negative value for free energy change

biological processes require more order so are usually positive

67
Q

what is reaction coupling

A

cells use a process called reaction coupling to carry out thermodynamically unfavourable reactions (anabolism and catabolism)
energy unfavourable reaction is driven by energy favourable reaction

68
Q

what value is incompatible with life

A

free energy = 0

principles of normal function (15 decks)

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