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Year 1 NSF > Cells and Tissues > Flashcards

Cells and Tissues Flashcards

1
Q

What does the force of muscle contraction depend on?

A

The number of cross bridges- compositions of motor unit, frequency of potentials, length tension relationship

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2
Q

What does and isometric contraction and isotonic contraction mean?

A

Isometric- same length of sarcomere so elastic elements extend, Isotonic- sarcomere shortens

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3
Q

How are graded muscle contractions achieved?

A

Changing the number and type of motor units that are activated

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4
Q

What is tetanus?

A

Sustained contraction with no relaxation due to large number of potentials

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5
Q

Why does length tension affect the force of contraction?

A

If the sarcomere is too short there is little shortening, if too long there is minimal cross bridge formation

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6
Q

What is energy stored in during rest?

A

High energy bonds in phosphocreatine- converted to creatine to release ATP

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7
Q

Where does ATP come from during exercise?

A

Initially the cytoplasm, then creatine, followed by glycolysis then oxidative phosphorylation,

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8
Q

What causes fatigue?

A

A reduction in sources of ATP

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9
Q

What sort of movement is Glycolytic (white) suited for?

A

Relies on anaerobic glycolysis so performs fast with high power contractions

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10
Q

What are some features of white muscle fibres?

A

Colour- little myoglobin, contain few mitochondria, contain glycogen

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11
Q

What exercise is oxidative (red) muscle fibres suited for?

A

Slow sustained activity

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12
Q

What are some features of red muscle fibres?

A

High myoglobin, surrounded by capillaries, lots of mitochondria

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13
Q

What is the function of myoglobin and how does it achieve this?

A

Myoglobin assists aerobic metabolism, by having a greater affinity for oxygen than haemoglobin for the muscle.

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14
Q

Where is smooth muscle found in the body?

A

GI tract, Uterus, Bladder, Eye, Blood vessels

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15
Q

How is the structure in smooth muscle different to skeletal muscle?

A

In smooth muscle there is less myosin, and there are no sarcomeres

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16
Q

What are key features of smooth muscle?

A

Small non-striated, spindle-shaper cells with single nucleus

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17
Q

Why can smooth muscles contract when stretched?

A

The myosin filaments are longer and covered in heads so can maintain enough overlap for optimal tension

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18
Q

Why are smooth muscles resistant to fatigue?

A

ATP mostly from oxidative phosphorylation and uses less energy then skeletal

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19
Q

What ion causes contraction in smooth muscle?

A

Calcium rise

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20
Q

How does calcium cause contraction in smooth muscle cells?

A

Calcium enters the muscle cell and binds to calmodulin activating myosin light chain kinase, which phosphorylates myosin which controls contraction

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21
Q

What causes Ca2+ to rise in smooth muscle?

A

External entry by voltage and ligand gated ion channels and some from the SR

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22
Q

What does myogenic mean?

A

No external stimuli needed for contraction, spontaneous

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23
Q

What are the two ways myogenic smooth muscle reaches threshold?

A

Pacemakers potentials oscillating membrane potentials that regularly reach threshold, or slow cyclic waves which gradually rise until threshold

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24
Q

How do multiunit smooth muscle cells differ?

A

Multiunit cells each have a terminal ending on every cell for fine control e.g iris

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25
Q

How do single unit cells spread excitation?

A

Gap junctions between cells

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26
Q

What neurotransmitter do sympathetic nerves release?

A

Noradrenaline

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27
Q

How can noradrenaline cause inhibition or excitation in smooth muscle?

A

Different receptors, alpha receptors cause excitation beta receptors cause inhibition

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28
Q

What causes smooth muscle relaxation?

A

Decrease in sarcoplasmic calcium using pumps and exchangers

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29
Q

What ions is intracellular high and low in?

A

High K+, low Na+, v low Ca2-,

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30
Q

What ions is extracellular fluid? high and low in

A

low Ca2+, low K+, high Na+

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31
Q

What does the rate of diffusion depend on?

A

Membrane permeability, voltage gradients, molecular weight, distance, surface area

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32
Q

What is simple diffusion?

A

Diffusion directly through lipid bilayer

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33
Q

What does facilitated diffusion require?

A

Non-energy requiring transporters

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34
Q

What are three differences between simple and facilitated diffusion?

A

Transport is specific, can be limited, can be inhibited in facilitated

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35
Q

What channels are permeable to water?

A

Aquaporins

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36
Q

What is osmolarity?

A

no of particles per litre of solution

37
Q

What is osmotic pressure?

A

The term used for exact amount of pressure required to stop osmosis

38
Q

What does Isoosmotic mean?

A

Solutions have the same conc of dissolved solutes

39
Q

What is hyperosmotic?

A

An increased osmotic pressure (increased solutes)

40
Q

What is hypoosmotic?

A

Decreased osmotic pressure due to less solutes

41
Q

What does isotonic mean?

A

No osmotic flow as the solutions are equal

42
Q

What are the 4 types of transporters?

A

Uniporter, Symporter, Antiporter, Ion channels

43
Q

What are the types of ion channels?

A

Ungated (leak), Voltage gated, Ligand gated, mechanical-gated

44
Q

What are the two types of active transport carriers?

A

primary- hydrolyses ATP, Secondary- uses potential energy (electrochemical gradient)

45
Q

What does an anti porter do?

A

More then 1 type of molecule transported simultaneously in the opposite direction

46
Q

What does the pump Na-K ATPase transport

A

3 Na+ out 2 K+ in

47
Q

What three pumps transport calcium out of cells

A

Ca ATPase, Na Ca exchanger, SR Ca ATPase (into SR in muscles)

48
Q

Why does myoglobin cause meat to go brown?

A

It converts to metmyoglobin

49
Q

What causes rigorous mortis and when does it set in?

A

When muscles run out of ATP cross bridges cannot be broken, 8-15 hours

50
Q

Why does hanging meat cause tenderness?

A

Proteolytic enzymes are released and breakdown the actin and myosin

51
Q

Where do ANS sensory neurones have their cell bodies?

A

The dorsal root ganglion

52
Q

What makes the peripheral nervous system?

A

Everything other then the brain and spinal cord

53
Q

How is the PNS subdivided?

A

Somatic, Autonomic, Enteric

54
Q

What does the somatic nervous system consists of?

A

sensory neurones that conduct impulses from cutaneous and special sense receptors to CNS and motor neurons that conduct impulses from CNS to skeletal muscle

55
Q

What does the autonomic system contain?

A

Sensory neurones from visceral organs and motor neurones from CNS to smooth muscle, cardiac and glands

56
Q

What does the enteric nervous system consist of?

A

enteric plexuses that extend the length of the GI tract

57
Q

What are the three ways signals can be passed through the PNS?

A

Nerves, Muscle, Endocrine cells

58
Q

What are the regions to nerve?

A

Cell body- nucleus, dendrites, single axon

59
Q

What is positive feedback?

A

When a rise in membrane potential causes more channels to open causing further depolarisation

60
Q

What are the three possible states of a voltage gated Na+ channel?

A

deactivated, activated, inactivated (closed and refractory)

61
Q

What causes hyper polarisation?

A

K+ channels which open and close slowly therefore further decreasing the membrane potential

62
Q

What is conduction called in a myelinated and non myelinated nerve cell?

A

Myelinated- saltatory conduction

Non- continuous conduction

63
Q

How does an inhibitory neurotransmitter work?

A

Hyperpolarises the postsynaptic membrane

64
Q

How is neurotransmitter removed from the synaptic cleft?

A

Diffusion, Eznyme degradation, uptake

65
Q

What is summation?

A

Several presynaptic bulbs releasing neurotransmitter to generate a nerve impulse

66
Q

What are the types of summation?

A

Spatial or temporal

67
Q

What are the neurotransmitters of the PNS?

A

Acetyl choline, adrenaline

68
Q

What are the similarities of a NMJ and a synapse?

A

Both have cleft, axon terminals store messenger, NT alter membrane potential

69
Q

What are the differences of a NMJ and a synapse?

A

NMJ nerve and muscle not nerve to nerve
No summation at NMJ
Always excitatory NMJ

70
Q

Where does the efferent neurone of the ANS leave the spinal cord?

A

Ventral Horn

71
Q

Where does the preganglionic neuron have its cell body in the ANS?

A

Within the CNS

72
Q

Where does the postganglionic neuron run?

A

Ganglion to the target tissue

73
Q

What is a normal reflex of the ANS?

A

Sensory to the CNS and automatic opposing motor response

74
Q

How is the autonomic nervous system divided?

A

Sympathetic and parasympathetic

75
Q

Which branch of the ANS is rest and digest?

A

Parasympathetic

76
Q

Which branch of the ANS is fight or flight

A

Sympathetic

77
Q

Where to the motor neurones of the parasympathetic emerge from?

A

Cranial nerves (brain stem) and the sacral spinal cord segments

78
Q

Are post/pre ganglionic of parasympathetic neurones short or long?

A

pre- long

post- short

79
Q

Which cranial nerves are the cranial preganglionic nerves in, in parasympathetic?

A

Cranial nerves III, VII, IX, X

80
Q

Are pre/post ganglionic sympathetic neurones short or long?

A

Pre- short

Post- long

81
Q

Where to sympathetic preganglionic neurones exit the spinal cord?

A

The thoracombular system between T1-T3

82
Q

Where are sympathetic ganglions found?

A

In the sympathetic trunk either side of the vertebral column or the prevertebral which are anterior to spinal column

83
Q

What are the 4 different pathways post ganglionic neurones take?

A

1) Enter spinal nerves via grey ramus and travel to extremities (blood vessels)
2) Separate nerves to heart
3) Synapse in prevertebral ganglia
4) In adrenal medulla

84
Q

What are the actions of the sympathetic system?

A

Increased HR, blood pressure, bronchodilation, pupil dilation, vasoconstriction, increase metabolism, increase sweating, decrease digestion

85
Q

What neurotransmitter do short myelinated preganglionic neurones release?

A

acetyl choline

86
Q

What neurotransmitter do longer unmyelinated postganlionic neurones release?

A

Noradrenaline

87
Q

What do long myelinated preganglionic neurones release?

A

Acetylcholine which binds to nektonic receptors

88
Q

What do short postganglionic unmyelinated neurones release?

A

acetyl choline which bind to muscarinic receptors

Year 1 NSF (11 decks)

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