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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
How do single unit cells spread excitation?
Gap junctions between cells
26
What neurotransmitter do sympathetic nerves release?
Noradrenaline
27
How can noradrenaline cause inhibition or excitation in smooth muscle?
Different receptors, alpha receptors cause excitation beta receptors cause inhibition
28
What causes smooth muscle relaxation?
Decrease in sarcoplasmic calcium using pumps and exchangers
29
What ions is intracellular high and low in?
High K+, low Na+, v low Ca2-,
30
What ions is extracellular fluid? high and low in
low Ca2+, low K+, high Na+
31
What does the rate of diffusion depend on?
Membrane permeability, voltage gradients, molecular weight, distance, surface area
32
What is simple diffusion?
Diffusion directly through lipid bilayer
33
What does facilitated diffusion require?
Non-energy requiring transporters
34
What are three differences between simple and facilitated diffusion?
Transport is specific, can be limited, can be inhibited in facilitated
35
What channels are permeable to water?
Aquaporins
36
What is osmolarity?
no of particles per litre of solution
37
What is osmotic pressure?
The term used for exact amount of pressure required to stop osmosis
38
What does Isoosmotic mean?
Solutions have the same conc of dissolved solutes
39
What is hyperosmotic?
An increased osmotic pressure (increased solutes)
40
What is hypoosmotic?
Decreased osmotic pressure due to less solutes
41
What does isotonic mean?
No osmotic flow as the solutions are equal
42
What are the 4 types of transporters?
Uniporter, Symporter, Antiporter, Ion channels
43
What are the types of ion channels?
Ungated (leak), Voltage gated, Ligand gated, mechanical-gated
44
What are the two types of active transport carriers?
primary- hydrolyses ATP, Secondary- uses potential energy (electrochemical gradient)
45
What does an anti porter do?
More then 1 type of molecule transported simultaneously in the opposite direction
46
What does the pump Na-K ATPase transport
3 Na+ out 2 K+ in
47
What three pumps transport calcium out of cells
Ca ATPase, Na Ca exchanger, SR Ca ATPase (into SR in muscles)
48
Why does myoglobin cause meat to go brown?
It converts to metmyoglobin
49
What causes rigorous mortis and when does it set in?
When muscles run out of ATP cross bridges cannot be broken, 8-15 hours
50
Why does hanging meat cause tenderness?
Proteolytic enzymes are released and breakdown the actin and myosin
51
Where do ANS sensory neurones have their cell bodies?
The dorsal root ganglion
52
What makes the peripheral nervous system?
Everything other then the brain and spinal cord
53
How is the PNS subdivided?
Somatic, Autonomic, Enteric
54
What does the somatic nervous system consists of?
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
What does the autonomic system contain?
Sensory neurones from visceral organs and motor neurones from CNS to smooth muscle, cardiac and glands
56
What does the enteric nervous system consist of?
enteric plexuses that extend the length of the GI tract
57
What are the three ways signals can be passed through the PNS?
Nerves, Muscle, Endocrine cells
58
What are the regions to nerve?
Cell body- nucleus, dendrites, single axon
59
What is positive feedback?
When a rise in membrane potential causes more channels to open causing further depolarisation
60
What are the three possible states of a voltage gated Na+ channel?
deactivated, activated, inactivated (closed and refractory)
61
What causes hyper polarisation?
K+ channels which open and close slowly therefore further decreasing the membrane potential
62
What is conduction called in a myelinated and non myelinated nerve cell?
Myelinated- saltatory conduction | Non- continuous conduction
63
How does an inhibitory neurotransmitter work?
Hyperpolarises the postsynaptic membrane
64
How is neurotransmitter removed from the synaptic cleft?
Diffusion, Eznyme degradation, uptake
65
What is summation?
Several presynaptic bulbs releasing neurotransmitter to generate a nerve impulse
66
What are the types of summation?
Spatial or temporal
67
What are the neurotransmitters of the PNS?
Acetyl choline, adrenaline
68
What are the similarities of a NMJ and a synapse?
Both have cleft, axon terminals store messenger, NT alter membrane potential
69
What are the differences of a NMJ and a synapse?
NMJ nerve and muscle not nerve to nerve No summation at NMJ Always excitatory NMJ
70
Where does the efferent neurone of the ANS leave the spinal cord?
Ventral Horn
71
Where does the preganglionic neuron have its cell body in the ANS?
Within the CNS
72
Where does the postganglionic neuron run?
Ganglion to the target tissue
73
What is a normal reflex of the ANS?
Sensory to the CNS and automatic opposing motor response
74
How is the autonomic nervous system divided?
Sympathetic and parasympathetic
75
Which branch of the ANS is rest and digest?
Parasympathetic
76
Which branch of the ANS is fight or flight
Sympathetic
77
Where to the motor neurones of the parasympathetic emerge from?
Cranial nerves (brain stem) and the sacral spinal cord segments
78
Are post/pre ganglionic of parasympathetic neurones short or long?
pre- long | post- short
79
Which cranial nerves are the cranial preganglionic nerves in, in parasympathetic?
Cranial nerves III, VII, IX, X
80
Are pre/post ganglionic sympathetic neurones short or long?
Pre- short | Post- long
81
Where to sympathetic preganglionic neurones exit the spinal cord?
The thoracombular system between T1-T3
82
Where are sympathetic ganglions found?
In the sympathetic trunk either side of the vertebral column or the prevertebral which are anterior to spinal column
83
What are the 4 different pathways post ganglionic neurones take?
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
What are the actions of the sympathetic system?
Increased HR, blood pressure, bronchodilation, pupil dilation, vasoconstriction, increase metabolism, increase sweating, decrease digestion
85
What neurotransmitter do short myelinated preganglionic neurones release?
acetyl choline
86
What neurotransmitter do longer unmyelinated postganlionic neurones release?
Noradrenaline
87
What do long myelinated preganglionic neurones release?
Acetylcholine which binds to nektonic receptors
88
What do short postganglionic unmyelinated neurones release?
acetyl choline which bind to muscarinic receptors

Year 1 NSF (11 decks)

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