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HUBS191 > Nervous System > Flashcards

Nervous System Flashcards

1
Q

what is the structure of a typical neuron?

A 
dendrites- 
cell body-
axon- 
axon hillock- 
axon terminal- 
myelin sheath-
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2
Q

what is the function of the dendrites of the neuron?

A

to receive information and transmit it to the cell body

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3
Q

what is the function of the cell body of the neuron?

A

the generic cell part of the neuron

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4
Q

what is the function of the axon hillock?

A

it is the part of the neuron that decides whether or not to transmit the electrical impulse it received further down the axon

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5
Q

what is the function of the axon?

A

the long process coming out of the cell body which carries electrical impulses down

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6
Q

what is the function of the myelin sheath?

A

acts to increase conduction velocity

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7
Q

what is the function of the axon terminal?

A

the end of the axon from which neurotransmitters are released

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8
Q

what is the myelin sheath? what forms it?

A

a lipid that wraps around the axon (because it is the plasma membrane of the cell)
CNS- formed by oligodendrocytes
PNS- formed by Schwann cells

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9
Q

what are the Nodes of Ranvier? why are the formed?

A

the gaps between the myelin sheaths on the axon

formed because axon is long, cells are short, so need multiple schwann cells to cover axon

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10
Q

what is the function of the schwann cells?

A

to form myelin sheath which increases conduction velocity

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11
Q

what is a disorder that occurs due to a problem with the myelin sheaths? why does it occur?

A

multiple sclerosis
it occurs because the immune system of the body attacks the myelin sheaths. this causes different axons to have different amounts of myelin on their axons, causing different electrical signal conduction speeds along different axons which leads to disjointed movement because there is no coordination of information transmission

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12
Q

what are the functional units of the axon? what are their components and functions?

A

input zone- consists of the dendrites and cell body
- receives information from other neurons
summation zone - axon hillock
- part of the neuron that decides to further conduct the message down the axon
conduction zone- axon
- part of the neuron along which the electrical impulse in conducted down
output zone- axon terminals
- part of the neuron from which neurotransmitters are released to the input zones of other neurons

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13
Q

name the morphological types of neurons

A

multipolar- multiple processes
bipolar- 2 processes
unipolar/pseudopolar- one process from cell body that then splits

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14
Q

what are the types of glia cells, where are the located?

A 
CNS:
- microglia: 
- astrocytes: 
- ependymal cells: 
- oligodendrocytes: 
PNS
- Schwann cells:
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15
Q

what is the function of the oligodendrocytes?

A

found in CNS: form myelin sheath in CNS and support neurons

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16
Q

what is the function of the microglia?

A

found in CNS: immune cells of CNS, can transform into phagocytes

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17
Q

what is the function of astrocytes?

A

found in CNS: form blood brain barrier, supply nutrients to neurons

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18
Q

what is the function of ependymal cells?

A

epithelial cells of the CNS, line the ventricles and circulate CSF with their cilia

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19
Q

what is the function of Schwann cells?

A

found in PNS: form myelin sheath in PNS and support peripheral nerves

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20
Q

what are the terms for a group of cell bodies and unmyelinated axons in the CNS and PNS?

A

CNS: nuclei, grey matter (cerebral cortex)
PNS: ganglia

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21
Q

what are the terms for a bundle of axons in the CNS and PNS?

A

CNS: tracts, white matter
PNS: nerves

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22
Q

what is the process by which information gets transmitted between neurons?

A

electrical signal down pre neuron axon to axon terminal, vesicles exocytose neurotransmitters into synapse which bind to receptors on post neuron causing electrical signal to go to axon hillock to determine whether to transmit signal further

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23
Q

name the types of synapses

A

axodendritic, axosomatic, axoaxonic

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24
Q

what is the afferent pathway? another name?

A

carries information towards the CNS from organs along afferent nerves. ascending

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25
Q

what is the efferent pathway? another name?

A

carries information away from CNS, towards effector organs along efferent nerves. descending

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26
Q

what are the two functional divisions of the nervous system?

A

somatic and autonomic

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27
Q

what types of informationis the somatic nervous system responsible for?

A

somatic efferent- voluntary muscle control

somatic afferent- sensory information we are aware of

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28
Q

what types of information is the autonomic nervous system responsible for?

A

autonomic efferent- involuntary muscle control

autonomic afferent- sensory information we are not aware of

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29
Q

what is the anatomical organisation of the somatic efferent division of the nervous system?

  • number of neurons and what are they like
  • location of cell bodies
  • hormone it releases
A
  • consists of one neuron
  • myelinated axon
  • cell body in CNS axon in PNS
  • releases Acteylcholine Ach
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30
Q

what is the anatomical organisation of the autonomic division of the nervous system?

  • number of neurons and what are they like
  • location of cell bodies
  • hormone it releases
A
  • consists of 2 neurons
  • neuron 1 is myelinated with cell body in CNS and synpase at autonomic ganglion
    neuron 2 is unmyelinated with cell body in PNS and synapse at effector organ
  • has 2 paths
  • releases Ach at first synapse and either Ach or NE at second
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31
Q

what are the 2 paths of the autonomic nervous system? what are their purposes?

A 
sympathetic 
- fight or flight
- prepares for stress response
parasympathetic
- rest and digest
- prepares for rest
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32
Q

what is the structure of the sympathetic nervous system?

A 
neuron 1
- short
- releases Ach
neuron 2
- long
- releases norepinephrine
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33
Q

what is the structure of the parasympathetic nervous system?

A 
neuron 1
- long
- releases Ach
neuron 2
- short
- releases Ach
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34
Q

what are the effects of the sympathetic nervous system?

A
  • increased pupil size
  • increased heart rate
  • increased sweating
  • increased blood pressure
  • constriction of blood vessels to supply more blood to muscles
  • decreased gastric motility
  • decreased salivation
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35
Q

what are the effects of the parasympathetic nervous system?

A
  • decreased pupil size
  • decreased heart rate
  • decreased sweating
  • decreased blood pressure
  • increased gastric motility
  • increased salivation
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36
Q

where does the sympathetic nervous system exit the CNS from?

A

sympathetic axons leave CNS at thoracolumbar level (T1-L2)

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37
Q

what is the name of, and where is the position of, the sympathetic ganglia?

A

sympathetic chain ganglia: located alongside vertebral column
- consists of chain ganglia (21-23 pairs) and collateral ganglia (3 main ganglia)

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38
Q

where does the parasympathetic nervous system exit the CNS from?

A

parasympathetic axons leave spinal cord at the cranial level, and the sacral level = craniosacral nerves

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39
Q

where is the position of the parasympathetic ganglia?

A

neuron 1 is long so ganglia where the neurons synapse is in or near the effector organs

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40
Q

where does the spinal cord start and finish?

A

starts at foramen magnum of skull and ends at L1

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41
Q

what is the meningeal sac?

A

a layer of connective tissue, called meninges, that line the skull and vertebral column and enclose the brain and spinal cord

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42
Q

where does the meningeal sac end?

A

at coccygeal level

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43
Q

what is the structure at which the spinal cord ends?

A

the conus medullaris

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44
Q

what is the conus medullaris?

A

the tapered lower end of the spinal cord

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45
Q

how does the spinal cord travel down the vertebral column?

A

it runs through spinal cavity in the vertebrae called the vertebral foramina

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46
Q

what is the cauda equina?

A

bundle of nerves that exit the spinal cord and vertebral column inferior to the end of the spinal cord

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47
Q

what nerves leave at the cauda equina?

A

legs, pelvis, abdomen

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48
Q

what is the filum terminale?

A

small piece of meninges that tethers the conus medullaris to the end of the meningeal sac

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49
Q

what is the function of the filum terminale?

A

to anchor the spinal cord in place, stabilising it to protect it from damage from hitting the sides of the meningeal sac

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50
Q

how do the nerves exit the spinal cord?

A

cervical and thoracic nerves exit through their respective vertebrae
lumbar and sacral nerves must grow down from the end of the spinal cord in order to exit through their respective vertebrae

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51
Q

what does the grey matter of the spinal cord contain? (ie-which neurons)

A

the cell bodies: of somatic efferent neuron, and of neuron 1 in autonomic nervous system (sympathetic and parasympathetic)

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52
Q

what are the parts of the grey matter in the spinal cord called?

A

dorsal horn and ventral horn

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53
Q

what are the parts of the white matter in the spinal cord called?

A

ventral column, lateral column, and dorsal column

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54
Q

what information travels in the dorsal part of the spinal cord?

A

sensory/afferent information

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55
Q

what information travels in the ventral part of the spinal cord

A

motor/efferent information

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56
Q

what is the dorsal column in the spinal cord made up of?

A

afferent axons that are conducting information up to the brain

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57
Q

what is the ventral column in the spinal cord made up of?

A

efferent axons that are conducting information down to the periphery

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58
Q

what is the lateral column in the spinal cord made up of?

A

a mixture of afferent axons conducting up to brain, and efferent axons conducting down to periphery

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59
Q

what is the dorsal root?

type of information?

A

the nerves that attach to spinal cord on dorsal side

- has one way flow of information to the brain (afferent)

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60
Q

what is the ventral root? type of information?

A

nerves that attach to spinal cord on ventral side

- one way flow of information to the periphery

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61
Q

what is the spinal nerve? type of information?

A

nerve where the dorsal and ventral nerve roots combine
also called the mixed nerve
- has 2 way flow of information

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62
Q

what is the dorsal root ganglion?

A

where the cell bodies of the sensory neurons in the dorsal root are located

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63
Q

what happens to the spinal nerve in the periphery? and why does this occur?

A

the spinal nerve splits into the ventral rami and dorsal rami. this is so that motor and sensory information can go to both sides of the body

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64
Q

what is the sympathetic rami? how many are there?

A

there are 2 sympathetic rami, they are small branches with the axons of neuron 1 from the sympathetic nervous system

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65
Q

what is the function of the sympathetic rami?

A

they branch off from the ventral rami to communicate with the sympathetic chain ganglia

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66
Q

what is the structure of the peripheral nerve?

A
  • axon which may or may not be myelinated
  • endoneurium surrounds axon
  • axons bundled into fascicles
  • perineurium surrounds fascicles
  • fascicles and blood vessels bundled up
  • bundle surrounded by epineurium
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67
Q

how many bones make up the cranium? how many are visible?

A

8 bones

7 are visible

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68
Q

what are the names of the visible bones of the cranium? and if more than one bone, how many?

A

frontal, parietal (2), temporal (2), occipital, sphenoid

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69
Q

what is the name of the bone of the cranium that is not visible?

A

the ethmoid bone

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70
Q

where is the frontal bone located?

A

anterior, it makes up the forehead

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71
Q

where are the parietal bones located?

A

lateral, on either side of the head

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72
Q

where are the temporal bones located?

A

lateral, on either side of the head where the ears are

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73
Q

where is the occipital bone located?

A

the most posterior bone

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74
Q

where is the sphenoid bone located?

A

it forms the back of the orbit (eye socket)

is one continuous bone that spans across the skull so is visible on either side of the skull

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75
Q

where is the ethmoid bone located?

A

it makes up the floor of the nasal bone

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76
Q

how are the cranial bones joined?

A

by fibrous joint called sutures

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77
Q

what are the names of the sutures and what bones do they join?

A 
coronal suture
- join frontal and parietal bones
lambdoidal suture
- join the occipital and parietal bones
squamous suture
- join the parietal and temporal bones
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78
Q

what are the sutures like at birth?

A

sutures have gaps in them called fontanelles

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79
Q

why are fontanelles present in the skull at birth?

A

because the skull needs to be flexible for birth and growth

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80
Q

how many facial bones are there? how many external?

A

there are 14 facial bones: 7 external

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81
Q

what are the names of the external facial bones, and if there is more than 1 bone, how many bones?

A 
nasal bones (2)
zygomatic bones (2)
maxillary bones (2)
mandible
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82
Q

where are the nasal bones located?

A

they are small bones that are located in between the eyes

83
Q

where are the zygomatic bones located?

A

they form the cheek bones

84
Q

where are the maxillary bones located?

A

part of the mouth where the upper teeth are

85
Q

where is the mandible located?

A

forms the jaw bone

86
Q

what are the three layers of meninges?

A

dura mater, arachnoid mater, and pia mater

87
Q

what is the function of the meninges?

A

it acts as a protective layer between the brain and the skull

88
Q

what is the structure of the dura mater?

A

consists of 2 layers called dural reflections

gap between the layers called venous sinus which is filled with venous blood

89
Q

what are the dural reflections? what are there names and function?

A

regions of the dura mater that separates major regions of the brain:
falx cerebri- separates the hemispheres of the cerebrum
falx cerebelli- separates the hemispheres of the cerebellum
tentorium cerebelli- separates the cerebrum and the cerebellum

90
Q

what is the function of the venous sinus?

A

is filled with venous blood to drain CSF out of the brain

91
Q

what is the structure of the arachnoid mater?

A

associated with blood vessels
has extensions called arachnoid villi/granulations
has a space between itself and pia mater called subarachnoid space

92
Q

what is the arachnoid villi/granulations? what is their function?

A

they are extensions of the arachnoid mater that protrude into the venous sinuses
they provide a path for the CSF to enter the blood

93
Q

what is the subarachnoid space and its function?

A

it is a space between the arachnoid mater and the pia mater

it is where blood vessels are located and where CSF circulates around the brain

94
Q

what is the pia mater? what is its structure?

A

the innermost layer of the meninges

it is transparent and delicate, closely follows the contours of the brain

95
Q

what are sulci and gyri?

A

sulci are valleys of the brain

gyri are hills of the brain

96
Q

what is the pathway of flow of CSF in the brain?

A

lateral ventricle -> 3rd -> cerebral aqueduct -> 4th -> arachnoid granulations -> venous sinuses -> venous blood -> drained from head

97
Q

where and how is CSF produced?

A

produced in the choroid plexus by separating from blood

98
Q

what is hydrocephalus and why does it occur?

A

increased intracranial pressure inside the skull

  • due to blockage in circulation and CSF not draining from head
  • occurs because there is no feedback to choroid plexus for CSF production
99
Q

what are the parts of the frontal lobe?

A

pre-frontal cortex, pre-motor cortex, and motor cortex

100
Q

what are each of the regions of the frontal lobe involved in?

A

pre-frontal cortex- deciding action and anticipation of consequence
pre-motor cortex- planning movement
motor cortex- execution of movement

101
Q

what is the frontal lobe involved in?

A

voluntary motor functions

102
Q

what is the parietal lobe involved in?

A

sensory functions

103
Q

what is the name of the part of the parietal lobe that receives sensory information?

A

somatosensory cortex or primary sensory cortex

104
Q

where is the somatosensory cortex located?

A

post central gyrus

105
Q

what is the occipital lobe involved in?

A

it is the primary visual centre of the brain

106
Q

what is the temporal lobe involved in?

A

hearing and short-term memory

107
Q

what are the main sulci in the brain? where are they located?

A

central sulcus- separates frontal and parietal lobes
parietal-occipital salcus
lateral sulcus- separates the temporal lobe from the parietal and frontal lobes

108
Q

what are the main gyri in the brain?

A

pre-central gyri
post-central gyri
- both are in relation to the central sulcus

109
Q

what is the main fissure in the brain? where?

A

transverse fissure

- separates the cerebellum and the cerebral cortex

110
Q

what is the structure of the brainstem?

A

consists of the midbrain, pons, and medulla oblongata

111
Q

what are the 3 types of white matter in the cerebral cortex?

A

commissural tracts, projection tracts, and association tracts

112
Q

what communication do commissural tracts allow?

A

allow communication between both sides of the cortex

113
Q

what communication do projection tracts allow?

A

communication between cortex and other region of CNS

114
Q

what communication do association tracts allow?

A

communication between one area of cerebral cortex and another

115
Q

what information does the corticospinal tract involve?

A

somatic efferent information

116
Q

what does the cerebrum consist of?

A

the cerebral cortex and corpus callosum

117
Q

what is the structure of the cerebral cortex?

A

outer layer of grey matter, inner layer is white matter

118
Q

what is the pathway for motor information to travel from the primary motor cortex?

A
  • cell body of neuron 1 is in the primary motor cortex
  • N1 crosses over to other side at the medulla in the brainstem
  • N1 enters spinal cord where its first synapse is
  • N2 synapses at NMJ before causing muscle to contract
119
Q

what is the function of the cerebellum?

A

to coordinate movement by comparing intended movement to actual movement and alerting brain to respond to discrepancies

120
Q

what are the basal ganglia/basal nuclei/deep nuclei?

A

are a collection of cell bodies in the CNS deep inside the brain

121
Q

what is the function of the basal ganglia?

A

are involved in modifying movement and helping to select, initiate, and terminate movement

122
Q

what is a disease associated with malfunction of the basal nuclei?

A

parkinson’s disease

123
Q

what causes parkinson’s disease?

A

the deep nuclei stop functioning properly due to loss of dopamine neurotransmitter which normally regulates basal nuclei. this means can’t initiate movement and cant stop movement

124
Q

what is the process of an action potential getting generated in a neuron?

A
  • stimulus triggers stimulus-gated Na+ channels to open
  • Na+ flows into the cell, causing it to become less negative
  • if the local depolarisation reaches the threshold potential, then voltage gated Na+ channels open
  • this causes further inflow of Na+ and further depolarisation
  • membrane reaches maximum depolarisation and voltage gated Na+ channels close while K+ channels open
  • K+ flows out of the cell, reducing the charge
  • membrane becomes hyperpolarised due to K+ channel not closing as soon as RMP is reached
  • closure of K+ channels and activity of Na+/K+ pump restores RMP
125
Q

how is the action potential conducted along the axon?

A

by electric fields from action potential in one region of the membrane activating adjacent voltage gated Na+ channels

126
Q

what is the refractory period?

A

the amount of time it takes until another action potential can happen

127
Q

what are the types of refractory period?

A

absolute- the period of time after an action potential when another action potential absolutely cannot happen
relative - the period of time after an action potential when another is possible only in response to a large stimulus

128
Q

what is the absolute refractive period? when does it occur during the action potential generation process?

A
  • period of time when another action potential absolutely cannot happen
  • begins when voltage Na+ channels are open
  • ends when the channels are closed again
129
Q

what is the relative refractory period? when does it occur during action potential generation?

A
  • period of time after an action potential where a large stimulus is required to generate another action potential
  • begins when voltage Na+ channels close
  • ends when voltage K+ channels close
130
Q

what are the things that determine the speed of the action potential?

A
  • myelinated axons
  • diameter of axon
  • refractory period
131
Q

how do myelinated axons increase the action potential conduction speed?

A

because action potential cant pass through myelin sheath so has to jump across nodes of ranvier. this is also where all the ion channels are concentrated in high density. high density of ion channels allows the production of a large electric field that can span across the myelin sheath to the next node off ranvier

132
Q

what are the types of synapses?

A

chemical synapse and electrical synapse

133
Q

what are the differences between electrical synapse and chemical synapse?

A

electrical synapse
- very fast signal transmission
- gap between neurons linked by gap junctions
chemical synapse
- relatively slower signal transmission
- a physical gap between the neurons which is linked by neurotransmitters

134
Q

describe the process of signal transmission in neuron 1

A
  • action potential travels down axon
  • at presynaptic bouton causes depolarisation
  • depolarisation causes activation of Ca2+ channels
  • Ca2+ flows into the cell
  • Ca2+ triggers vesicles to fuse with membrane
  • neurotransmitters released into synaptic cleft
135
Q

describe the process of synaptic transmission in neuron 2

A
  • neurotransmitters bind to receptors on neuron 2
  • binding to receptors activates the opening of channels
  • response of cell is different depending on which channel is activated
136
Q

what occurs during synaptic transmission when Na+ channels are activated?

A
  • Na+ channels open
  • Na+ flows into the cell
  • causes depolarisation
  • depolarisation causes K+ channels to open
  • cell depolarises and passes on depolarisation down axon
  • in flow of K+ into the cell causes repolarisation
137
Q

what occurs when Cl- channels are activated during synaptic transmission?

A
  • activation of Cl- channels causes Cl- to flow into the cell
  • flow of Cl- causes hyperpolarisation in the cell
138
Q

what is the effect of depolarisation on the post synaptic neuron? what is the term for this?

A
  • depolariation is excitatory

- the temporary depolarisation of the post synpatic membrane is called the excitatory post synaptic potential (EPSP)

139
Q

what is the effect of Cl= on the post synaptic neuron? what is the term

A
  • Cl- flowing into the cell causes hyperpolarisaton
  • hyperpolarisation is inhibitory
  • this is called inhibitory post synaptic potential (IPSP)
140
Q

in synaptic transmission, how are the ways that the signal can be stopped?

A
  • enzyme degradation
    enzymes released into synapse breakdown neurotransmitters and thus stop the signal
  • reuptake into neurons
    carrier molecules bind to neurotransmitter and transports across cell membrane
  • reuptake into glial cells
141
Q

what is an ionotropic receptor?

A

a receptor that causes the opening of a channel once bound by a neurotransmitter

142
Q

what is a metabotropic receptor

A

a receptor which acts through a second messenger system

143
Q

what are the main types of neurotransmitter?

A

excitatory (EPSP)
- cause depolarisation
inhibitory (IPSP)
- causes hyperpolarisation

144
Q

what are some examples of excitatory neurotransmitters?

A
  • acetylcholine

- glutamate

145
Q

what is an example of inhibitory neurotransmitters?

A

GABA

gamma amino butyric acid

146
Q

where is acetlycholine used? what effect does it have? type of receptor?

A
  • neuromuscular junction (for muscle contraction) and brain

- it activates stimulus-gated Na+ channels

147
Q

where is glutamate used? what effect does it have? type of receptor?

A
  • most common excitatory neurotransmitter in CNS
  • activates stimulus-gated Na+ and Ca2+ channels
  • no receptor information given
148
Q

where is GABA used? what effect does it have? type of receptor?

A
  • most common inhibitory neurotransmitter in the brain
  • activates Cl- and K+ channels
  • Cl- channels are ionotropic K+ channels are metabotropic
149
Q

what is the threshold frequency?

A

about -59mV

150
Q

what spatial summation?

A

the addition of excitatory and inhibitory inputs that arrive at different synaptic knobs

151
Q

what is temporal summation?

A

the addition of action potentials that arrive at an axon within a short period of time (before the membrane of the neuron has repolarised)

152
Q

what are the types of synaptic network?

A
  • divergence

- convergence

153
Q

what are the advantages of a divergent synaptic network?

A
  • allows signal to be amplified

- allows for coordination of information between different areas of the brain

154
Q

what are the advantages of a convergent synaptic network?

A
  • redundancy, if one presynaptic nerve stopped working the postsynaptic nerve will still be functional
  • provides a number of control points, so many different regions of the brain can contribute to the activity of the postsynaptic neuron
155
Q

what are the stages of muscle contraction?

A

excitation
contraction
relaxation

156
Q

what does the excitation stage of muscle contraction involve?

A
  • AP reaches end of motor neuron
  • activates voltage gated Ca2+ channels
  • Ca2+ flows into axon terminal
  • triggers release of neurotransmitters (Ach) into synaptic cleft
  • synaptic transmission occurs
  • activation of Ach receptors which are gate keepers for stimulus gated Na+ channels
  • Na+ flows into cell, depolarising it
157
Q

what does synaptic transmission involve?

A
  • Ach diffuses across synaptic cleft
  • Ach binds to nicotinic cholinergic receptors
  • receptors are gate keepers for stimulus gated Na+ channels which open in response to binding
158
Q

what does the contraction stage of muscle contraction involve?

A
  • AP travels along sarcolemma and into t-tubules in muscle cells, depolarising
  • depolarising activates Ca2+ channels on SR to to open
  • Ca2+ diffuses out of SR into the cell
  • Ca2+ binds to troponin-tropomyosin complex->shape change to open up binding site
  • myosin heads bind to active site on actin to form cross bridge
  • power stroke = sliding filaments
159
Q

what is involved in the process of relaxation in muscle contraction?

A
  • no new AP, sarcolemma repolarises
  • no Ca2+ release from SR into sarcoplasm because channels close
  • Ca2+ pumped back into SR
  • reduced concentration in sarcolemma so doesnt bind to troponin anymore
  • actin and myosin still bound, must be unbound by ATP binding to myosin heads
160
Q

what is a twitch?

A

a single muscle contraction caused by a single action potential in a single motor unit

161
Q

how are twitches caused?

A

repeated stimulus with a certain time interval between stimuli, causes contractions with increasing levels of tension

162
Q

why do contractions in twitches having increasing levels of tension?

A

there are sustained higher levels of Ca2+ in sacroplasm
- makes actin-myosin interactions more sensitive to Ca2+ = stronger and more binding
-> more muscle contraction = more heat production
muscles at higher heat produce more tension

163
Q

what are the stages of a twitch?

A

latent period, contraction phase, and relaxation phase

164
Q

what is treppe?

A

the effect that a series of spaced twitches increases the tension of contraction more than just a single twitch

165
Q

what is tetanus and what condition must be in place for it to occur?

A

rapidly repeated stimuli cause higher levels of tension that result in summation of the tension curves produced
- in order to occur, time between stimuli must be reduced in order to produce series of closely spaced twitches

166
Q

what are the types of tetanus and what makes them different?

A

incomplete tetanus
- fluctuations between individual twitches is visible
complete tetanus
- fluctuations not visible

167
Q

why does tetanus occur?

A

main mechanism is sustained high levels o Ca2+
- because stimuli are so frequent that when Ca2+ levels increase, they can never fully return to normal basal levels
actin-myosin interactions are more sensitive in high Ca2+ = more muscle contractions = more heat = more tension in contractions

168
Q

what are the energy sources required for muscle contraction?

A

ATP and CP (creatine phosphate)

169
Q

what is the role of ATP?

A

-it is the structure which delivers energy (provides all energy for skeletal muscle contraction)

170
Q

how long can the store of ATP we have in our bodies sustain a contraction for?

A

limited store of ATP

=maximum contraction of skeletal muscles for 2-4s

171
Q

what is CP? what is its role?

A

creatine phosphate

- in skeletal muscles as a back up system for ATP

172
Q

how does CP perform its function?

A

it is broken down and the energy generated is used to convert ADP back into ATP

173
Q

how long can the store of CP we have in our bodies sustain a contraction for?

A

limited store of CP

= can make enough ATP to sustain contraction for 20s

174
Q

what is the back up system to ATP and CP?

A

metabolism of food

175
Q

when is energy required during muscle contraction? why?

A
  • only during the relaxation period

- because energy is required to pump Ca2+ back into the SR and to detach myosin from actin

176
Q

what is rigor mortis?

A

muscle stiffness that occurs after body has run out of energy (ATP)

177
Q

why does rigor mortis occur?

A

no energy is required in excitation or contraction stages of muscle contraction so muscles can become excited when energy stores are depleted, but there is no energy to uncouple the cross bridges formed between actin and mysoin so muscles cant relax and remain in excited state

178
Q

what is the oxygen binding protein in muscles? how many oxygens can it bind?

A

myoglobin

can bind one oxygen

179
Q

what are the types of muscle fibre? include all their names (3)

A
  • red/slow/type I
  • intermediate/type IIa
  • white/fast/type IIx
180
Q

what are some of the features of red muscle fibres? (myoglobin, metabolism, diameter, speed. energy consumption, sustained)

A
  • high myoglobin
  • uses aerobic metabolism
  • small diameter
    to allow oxygen to diffuse
  • slow force production and energy consumption
    -can sustain contraction for long periods of time
181
Q

features of white muscle? (myoglobin, metabolism, diameter, speed. energy consumption, sustained)

A
  • low myoglobin
    hence white muscle colour
  • uses anaerobic metabolism
    -large diameter
    because doesnt need oxygen to diffuse through
  • fast force production and energy consumption
  • cannot sustain contraction for long periods of time
182
Q

what is an example of a muscle made up of slow muscle fibres?

A

soleus

183
Q

what is an example of a muscle made up of type IIx muscle fibres?

A

internal rectus

-the muscle in the eye

184
Q

what is the effect of strength training on muscle physiology?

A

-hypertrophy
more sarcomeres produced so
-muscles get bigger
-more anaerobic metabolism

185
Q

what is the effect of endurance training on muscle physiology?

A

-increase blood supply to muscle
-more blood vessels
-more mitochondria
-more aerobic enzymes
thus improved aerobic metabolism

186
Q

what is the effect of disuse on muscle physiology?

A

-atrophy
sarcomeres are broken down so
-smaller muscles
-less power

187
Q

what is fatigue? cause?

A

a state of exhaustion

  • loss of strength or endurance
  • caused by strenuous muscle activity
188
Q

what are the types of fatigue?

A

physiological fatigue

psychological fatigue

189
Q

what is physiological fatigue?

A

there is an ATP depletion

build up of metabolic by-products (Pi and lactic acid)

190
Q

what is psychological fatigue?

A

feedback from working muscle to brain which produces sensation of fatigue, even though still capable of contracting
(feed forward)

191
Q

what are the functions of each of the muscle types?

A 
skeletal
- movement
- heat
- posture
cardiac
- pump blood
smooth
- movement of contents of viscera
192
Q

what is the structure of cardiac muscle?

A

consist of branching network of myocytes that are connected by intercalated discs

193
Q

what are intercalated discs? what features do they give to the muscle type they are associated with?

A
  • the place where the plasma membranes of 2 myocytes connect
  • have gap junctions and desmosomes
  • give cardiac muscle electrical communication and mechanical connection between cells
194
Q

what is the structure of smooth muscle?

A

consist of spindle-shaped cells
no sarcomeres
-has dense bodies located randomly, which are connected by myofilaments

195
Q

what is the contraction of smooth muscle like? why?

A

contraction occurs in all directions and is weaker

-this is because the myofilaments are arranged in all directions

196
Q

what are the types of smooth muscle cell and how are they different? what about their structure makes them different?

A

-single unit smooth muscle
smooth muscle cells that work as a single unit
multi
bc is organised in sheet and has gap junction
- multi unit smooth muscle
individual cells which are not connected together
no gap junctions

197
Q

how does smooth muscle achieve vasoconstriction and vasodilation?

A

smooth muscle lies on top of blood vessel:
when relaxed it becomes thinner=increase in blood vessel diameter
when contracted, becomes thicker=reducing blood vessel diameter

198
Q

how is the muscle contraction of smooth muscle different to the muscle contraction of skeletal muscle?

A

Ca-calmodulin-MLCK-MLC

  • Ca2+ binds to calmodulin instead of troponin (because smooth muscle doesnt have troponin) =
  • Ca2+ calmodulin complex activates MLCK (myosin light chain kinase)
  • MLCK activates MLC (myosin light chain) hich activated the cross bridge
  • phosphorylation of MLC initiates the contraction
199
Q

muscle types - striations?

A

skeletal - striated
smooth - no striated
cardiac - striated

200
Q

muscle types- AP spread from cell to cell?

A

skeletal - no
smooth - yes(single-unit)
smooth - no(multi-unit)
cardiac - yes

201
Q

what does syncitium mean?

A

muscle works as a whole

202
Q

muscle types- control?

A

skeletal- voluntary
smooth - involuntary
cardiac - involuntary

203
Q

muscle types- speed of contraction?

A

skeletal - fast
smooth - very slow
cardiac - slow

HUBS191 (3 decks)

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