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1

How does a stimulus travel in the nervous system?

stimulus - receptors - central nervous system - effectors - response

2

what are sensory receptors and what do they do

convert energy of a stimulus (light or chemical energy) into electrical energy used to send nerve impulses
-act as transducers

3

describe the neurone when is at resting state

difference in charge across membrane, there is a voltage
also called potential difference
at rest resting potential

4

how is the difference in charge generated

by ion pump and ion channels

5

what does happen to the resting potential when the membrane is excited?

-membrane becomes more permeable
-more ions movement
-change in potential difference, GENERATOR PETENTIAL

6

what happens with a bigger generator potential?

-membrane more excited
-more permeable
-bigger ions movement
-bigger change

7

what happens when generator potential is big enough ?

triggers an action potential

8

what is a pacinian corpuscle

a mechanic receptor, detects mechanical stimuli (pressure and vibration)

9

structure of pacinian corpuscle

- contain end of sensory neurone, sensory nerve ending
-wrapped in layers of connective tissue; LAMELLAE

10

what happens when the pacinian corpuscle detects a stimulus?

-lamellae deform pressing on sensory nerve ending
-causing the deformation of stretch-mediated sodium channels (in neurone membrane)
-sodium channels open
-sodium ions diffuse into the cell
-generator potential is created
-if reaches the threshold potential it will trigger an action potential

11

three types of neurone

sensory, motor, relay

12

describe sensory neurone

-many short dendrites, one long dendron
-one short axon
-from receptor cells (cell body) to cns

13

describe motor neurone

- many short dendrites
-one long axon
-from cns (cell body) to effector cells

14

describe relay neurone

-many short dendrites
-many short axons
-from sensory neurones (cell body) to motor neurones

15

how is the membrane said to be when at rest

polarised

16

how much is the resting potential

-70mV

17

how is the resting potential maintained

sodium potassium pump
potassium ion channel

18

how does the sodium potassium pump works

3 sodium ions are actively pumped out of the membrane which isn't permeable to sodium ions, they can't diffuse back in
-SODIUM ION ELECTROCHEMICAL GRADIENT is more positive inside
2 potassium ions are pumped in membrane which is permeable to potassium ion and they can diffuse out

19

how do potassium ion diffuse out of the membrane?

potassium ion channel

20

how is the charge of the membrane during resting potential

the outside of the membrane is positively charged compared to the inside

21

which are the 5 stages of an action potential?

1. stimulus
2. depolarisation
3. repolarisation
4. hyperpolarisation
5. resting state

22

what does a stimulus do to the neurones membrane

-excites it
-sodium ions channels open
-membrane more permeable to sodium ions
-diffuse down sodium ion electrochemical gradient
-diffuse inside the neurone
-inside of the membrane becomes less negative

23

what happens during depolarisation

If potential difference reaches the threshold potential
voltage-gated sodium channels open
more sodium ions enter the cell, positive feedback

24

how much is the threshold potential

-55mV

25

what happens during repolarisation

-when potential difference is around 33mV sodium channels close
-potassium channels open
-membrane becomes more permeable to potassium ions
-potassium ions diffuse out down the potassium ions concentration gradient
-membrane starts to enter in resting potential

26

what happens during hyperpolarisation

-potassium ions channels are slow to close
-for a bit too many potassium ions diffuse out
-potential difference is more negative than resting potential

27

what happens during the resting state

- membrane is at resting potential

28

what is the refractory period

when membrane can't be excited again yet because channels are recovering

29

when are the ions channel in refactory period?

sodium ions channels during repolarisation are closed
potassium ions channels are closed during hyperpolariasation

30

how does an action potential move along the neurone?

wave of depolarisation
-sodium ions enter and diffuse side ways
-causes sodium ions channel in next region to open
-moves away from parts in refractory

31

what does all-or-nothing mean?

-if threshold potential is reached action potential will always fire
-if not it won't

32

what does a bigger stimulus do to an action potentials

action potentials isn't bigger
will cause to fire action potentials more frequently

33

what are myelinated neurones, whats their structure?

-have a myelinated sheath made of Swann cells
-between Swann cells there are nodes of Ranvier (small gaps) where sodium ions channels are concentrated

34

how do action potential travel in myelinated neurones

-depolarisation only happens in nodes
-neurones cytoplasm conducts enough electrical charge to depolarise next node
-impulse 'jumps' from node to node - SALTATORY CONDUCTION

35

what are synapses

junctions between neurones or neurone and effector cells

36

what are synapses that use Ach called?

cholinergic synapses

37

how is the gap called

synaptic clef

38

how is the swelling at the end of presynaptic neurone called

synaptic knob

39

how do cholinergic synapses work?

-action potential reaches ent of presynaptic neurone
-acetylcholine released in synaptic clef
-bind to cholinergic receptors
-trigger an action potential in postsynaptic neurone

40

what happens to neurotransmitters that remain in clef?

-go back in presynaptic neurone
-broken down by enzyme

41

how is acetylcholine removed from clef

an enzyme (acetylcholinesterase) it down

42

how do synapses work?

1. action potential arrives at the synaptic knob
-stimulates voltage gated calcium ion channels to open
-calcium ion diffuse in (pumped out afterwards - active transport)
2.influx of calcium ions move vesicle
-fuse with presynaptic membrane - exocytosis
-neurotransmitters in synaptic clef
3. bind to specific receptors in post synaptic membrane
-cause sodium ion channels to open
-sodium ions influx causes depolarisation
-action potential generated if threshold is reached
5. neurotransmitters removed from clef so that response doesn't keep happening.

43

how do synapses interact together

-convergence
-divergence
-summation

44

describe divergence

one neurone connects to many neurones
-info is dispersed in different parts of the body

45

describe convergence

many neurones connect to one
-information is amplified

46

what is summation?

combination of effect of neurotransmitters combined to reach the threshold potential.

47

how can summation be?

spatial
temporal

48

describe spatial summation

convergence
signals from different stimulus combined

49

describe temporal summation

2 or more impulses in quick succession from the same presynaptic neurone
-more neurotransmitters released in clef
-action potential is more likely to happen

50

how do synapses ensure that impulse travels in one direction

having receptors only in post synaptic membrane.

51

which are the components of the hormonal system?

endocrine glands and hormones

52

what are hormones

chemical messengers
-proteines/peptides
-steroids

53

who are endocrine glands stimulated?

change in concentration of a substance
electrical impulses

54

what happens what endocrine glands are stimulated?

hormones are secreted directly into the blood
and diffuse out all over the body, bind to specific receptors in target cells
they will give a response

55

what is hormone said to be and why

first messenger
carries message from endocrine glands to receptors

56

what happens when an hormone binds to a receptor?

activates an enzyme in cell membrane that catalyses the production of a signalling molecule (inside cell)

57

(hormonal communication) what is the signalling molecule said to be?

second messenger

58

(hormonal communication) what does the signalling molecule do

single mother parts to change how cell works
activates a cascade inside cell

59

adrenal gland, whats the first messenger

adrenaline

60

what does adrenaline do once released

binds to receptors and activates adenylyl cyclase (enzyme)

61

what does adenylyl cyclase do

catalyses the production of the second messenger

62

adrenal gland, what is the second messenger?

cyclic AMP from ATP

63

what does cyclic AMP do?

activate a cascade to break down glycogen into glucose, more energy

64

where are adrenal gland found?

above kidneys

65

structure of adrenal gland

2 parts, cortex and medulla

66

what does the cortex of adrenal gland secrete?

steroids hormones eg. cortisol / aldosterone

67

steroid hormones secreted by adrenal gland are a response to?

short term and long term stress

68

what is the body response to steroid hormones released by adrenal gland?

-stimulate the break down of proteins and fats, more glucose available
-increase blood volume and pressure by increasing the uptake of sodium ions and water by kidneys
-suppressing immune system

69

what does the medulla of adrenal gland secrete?

catecholamine hormones (adrenaline/ noradrenaline)

70

what does adrenaline cause in the body and how

make more energy in short-term
-increase heart and breathing rate
-cause break down of glycogen into glucose
-constricting some blood vessels, blood diverted into brain and muscles

71

what area of the pancreas contains endocrine tissue?

islets of Langerhans

72

where are islets of langerhans found?

around blood capillaries

73

where do islets of langerhans secrete the hormones

directly into the blood

74

what are the 2 type of cells is islets of langerhans &what do they secrete

alpha cells secrete glucagon
beta cells secrete insulin

75

disease where blood glucose concentration can't be controlled

diabetes mellitus

76

describe type 1 diabetes

-auto-immune disease, body attack and destroys beta cells
-insuline isn't produced
-if blood glucose concentration increases it will stay high
-kidneys can't reabsorb all glucose, some is excreted in urine
-usually develops in children or young adults, links to family history

77

treatments for type 1 diabetes

insuline therapy
islets transplantation
monitor blood glucose concentration

78

describe insuline therapy

regular insulin injections during the day
or insuline pump, machine with a tube that releases insulin in body through a tube

79

describe islets transplantation

pancreas produces more insulin

80

how do we monitor blood glucose concentration

healthy and balanced diet
activity, regular exercise

81

describe type 2 diabetes

-beta cells don't produce enough insulin or insulin receptors don't work properly
-blood glucose concentration is higher than normal
-develops alter in life and is linked with obesity
-increased chances if African /asian/family history of disease

82

treatments for type 2 diabetes

life style changes
medication
insuline therapy

83

describe medication to treat type 2 diabetes

-metformin, acts on livers cells,
reduces the amount of glucose released
increase sensibility of cells to insulin, more glucose is taken up
-sulfonylureas stimulates production of insulin
-thiazolidinediones makes body cells more sensitive to insulin

84

where was insulin taken from for insulin therapy in the past?

pig pancreas

85

where is insulin taken from for insulin therapy nowadays ?

made by genetically modified bacteria

86

what are the advantages of using genetically modified bacteria for insulin

cheaper
larger quantities are produced
allergic responses or rejection are less likely
ethical religious reasons

87

what other therapy is being developed to treat diabetes

stem cells
grown into beta cells

88

whats the normal blood glucose concentration?

90 mg per 100cm2

89

how does blood glucose concentration rises and fall

rises by eating carbohydrates
falls with exercise - more glucose used in respiration

90

which are the two hormones that control blood glucose concentration?

glucagon
insuline