Nervous System Flashcards
(203 cards)
1
Q
what is the structure of a typical neuron?
A
dendrites- cell body- axon- axon hillock- axon terminal- myelin sheath-
2
Q
what is the function of the dendrites of the neuron?
A
to receive information and transmit it to the cell body
3
Q
what is the function of the cell body of the neuron?
A
the generic cell part of the neuron
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
5
Q
what is the function of the axon?
A
the long process coming out of the cell body which carries electrical impulses down
6
Q
what is the function of the myelin sheath?
A
acts to increase conduction velocity
7
Q
what is the function of the axon terminal?
A
the end of the axon from which neurotransmitters are released
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
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
10
Q
what is the function of the schwann cells?
A
to form myelin sheath which increases conduction velocity
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
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
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
14
Q
what are the types of glia cells, where are the located?
A
CNS: - microglia: - astrocytes: - ependymal cells: - oligodendrocytes: PNS - Schwann cells:
15
Q
what is the function of the oligodendrocytes?
A
found in CNS: form myelin sheath in CNS and support neurons
16
Q
what is the function of the microglia?
A
found in CNS: immune cells of CNS, can transform into phagocytes
17
Q
what is the function of astrocytes?
A
found in CNS: form blood brain barrier, supply nutrients to neurons
18
Q
what is the function of ependymal cells?
A
epithelial cells of the CNS, line the ventricles and circulate CSF with their cilia
19
Q
what is the function of Schwann cells?
A
found in PNS: form myelin sheath in PNS and support peripheral nerves
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
21
Q
what are the terms for a bundle of axons in the CNS and PNS?
A
CNS: tracts, white matter
PNS: nerves
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
23
Q
name the types of synapses
A
axodendritic, axosomatic, axoaxonic
24
Q
what is the afferent pathway? another name?
A
carries information towards the CNS from organs along afferent nerves. ascending
25
what is the efferent pathway? another name?
carries information away from CNS, towards effector organs along efferent nerves. descending
26
what are the two functional divisions of the nervous system?
somatic and autonomic
27
what types of informationis the somatic nervous system responsible for?
somatic efferent- voluntary muscle control
| somatic afferent- sensory information we are aware of
28
what types of information is the autonomic nervous system responsible for?
autonomic efferent- involuntary muscle control
| autonomic afferent- sensory information we are not aware of
29
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
- consists of one neuron
- myelinated axon
- cell body in CNS axon in PNS
- releases Acteylcholine Ach
30
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
- 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
31
what are the 2 paths of the autonomic nervous system? what are their purposes?
```
sympathetic
- fight or flight
- prepares for stress response
parasympathetic
- rest and digest
- prepares for rest
```
32
what is the structure of the sympathetic nervous system?
```
neuron 1
- short
- releases Ach
neuron 2
- long
- releases norepinephrine
```
33
what is the structure of the parasympathetic nervous system?
```
neuron 1
- long
- releases Ach
neuron 2
- short
- releases Ach
```
34
what are the effects of the sympathetic nervous system?
- 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
35
what are the effects of the parasympathetic nervous system?
- decreased pupil size
- decreased heart rate
- decreased sweating
- decreased blood pressure
- increased gastric motility
- increased salivation
36
where does the sympathetic nervous system exit the CNS from?
sympathetic axons leave CNS at thoracolumbar level (T1-L2)
37
what is the name of, and where is the position of, the sympathetic ganglia?
sympathetic chain ganglia: located alongside vertebral column
- consists of chain ganglia (21-23 pairs) and collateral ganglia (3 main ganglia)
38
where does the parasympathetic nervous system exit the CNS from?
parasympathetic axons leave spinal cord at the cranial level, and the sacral level = craniosacral nerves
39
where is the position of the parasympathetic ganglia?
neuron 1 is long so ganglia where the neurons synapse is in or near the effector organs
40
where does the spinal cord start and finish?
starts at foramen magnum of skull and ends at L1
41
what is the meningeal sac?
a layer of connective tissue, called meninges, that line the skull and vertebral column and enclose the brain and spinal cord
42
where does the meningeal sac end?
at coccygeal level
43
what is the structure at which the spinal cord ends?
the conus medullaris
44
what is the conus medullaris?
the tapered lower end of the spinal cord
45
how does the spinal cord travel down the vertebral column?
it runs through spinal cavity in the vertebrae called the vertebral foramina
46
what is the cauda equina?
bundle of nerves that exit the spinal cord and vertebral column inferior to the end of the spinal cord
47
what nerves leave at the cauda equina?
legs, pelvis, abdomen
48
what is the filum terminale?
small piece of meninges that tethers the conus medullaris to the end of the meningeal sac
49
what is the function of the filum terminale?
to anchor the spinal cord in place, stabilising it to protect it from damage from hitting the sides of the meningeal sac
50
how do the nerves exit the spinal cord?
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
51
what does the grey matter of the spinal cord contain? (ie-which neurons)
the cell bodies: of somatic efferent neuron, and of neuron 1 in autonomic nervous system (sympathetic and parasympathetic)
52
what are the parts of the grey matter in the spinal cord called?
dorsal horn and ventral horn
53
what are the parts of the white matter in the spinal cord called?
ventral column, lateral column, and dorsal column
54
what information travels in the dorsal part of the spinal cord?
sensory/afferent information
55
what information travels in the ventral part of the spinal cord
motor/efferent information
56
what is the dorsal column in the spinal cord made up of?
afferent axons that are conducting information up to the brain
57
what is the ventral column in the spinal cord made up of?
efferent axons that are conducting information down to the periphery
58
what is the lateral column in the spinal cord made up of?
a mixture of afferent axons conducting up to brain, and efferent axons conducting down to periphery
59
what is the dorsal root?
| type of information?
the nerves that attach to spinal cord on dorsal side
| - has one way flow of information to the brain (afferent)
60
what is the ventral root? type of information?
nerves that attach to spinal cord on ventral side
| - one way flow of information to the periphery
61
what is the spinal nerve? type of information?
nerve where the dorsal and ventral nerve roots combine
also called the mixed nerve
- has 2 way flow of information
62
what is the dorsal root ganglion?
where the cell bodies of the sensory neurons in the dorsal root are located
63
what happens to the spinal nerve in the periphery? and why does this occur?
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
64
what is the sympathetic rami? how many are there?
there are 2 sympathetic rami, they are small branches with the axons of neuron 1 from the sympathetic nervous system
65
what is the function of the sympathetic rami?
they branch off from the ventral rami to communicate with the sympathetic chain ganglia
66
what is the structure of the peripheral nerve?
- 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
67
how many bones make up the cranium? how many are visible?
8 bones
| 7 are visible
68
what are the names of the visible bones of the cranium? and if more than one bone, how many?
frontal, parietal (2), temporal (2), occipital, sphenoid
69
what is the name of the bone of the cranium that is not visible?
the ethmoid bone
70
where is the frontal bone located?
anterior, it makes up the forehead
71
where are the parietal bones located?
lateral, on either side of the head
72
where are the temporal bones located?
lateral, on either side of the head where the ears are
73
where is the occipital bone located?
the most posterior bone
74
where is the sphenoid bone located?
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
75
where is the ethmoid bone located?
it makes up the floor of the nasal bone
76
how are the cranial bones joined?
by fibrous joint called sutures
77
what are the names of the sutures and what bones do they join?
```
coronal suture
- join frontal and parietal bones
lambdoidal suture
- join the occipital and parietal bones
squamous suture
- join the parietal and temporal bones
```
78
what are the sutures like at birth?
sutures have gaps in them called fontanelles
79
why are fontanelles present in the skull at birth?
because the skull needs to be flexible for birth and growth
80
how many facial bones are there? how many external?
there are 14 facial bones: 7 external
81
what are the names of the external facial bones, and if there is more than 1 bone, how many bones?
```
nasal bones (2)
zygomatic bones (2)
maxillary bones (2)
mandible
```
82
where are the nasal bones located?
they are small bones that are located in between the eyes
83
where are the zygomatic bones located?
they form the cheek bones
84
where are the maxillary bones located?
part of the mouth where the upper teeth are
85
where is the mandible located?
forms the jaw bone
86
what are the three layers of meninges?
dura mater, arachnoid mater, and pia mater
87
what is the function of the meninges?
it acts as a protective layer between the brain and the skull
88
what is the structure of the dura mater?
consists of 2 layers called dural reflections
| gap between the layers called venous sinus which is filled with venous blood
89
what are the dural reflections? what are there names and function?
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
what is the function of the venous sinus?
is filled with venous blood to drain CSF out of the brain
91
what is the structure of the arachnoid mater?
associated with blood vessels
has extensions called arachnoid villi/granulations
has a space between itself and pia mater called subarachnoid space
92
what is the arachnoid villi/granulations? what is their function?
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
what is the subarachnoid space and its function?
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
what is the pia mater? what is its structure?
the innermost layer of the meninges
| it is transparent and delicate, closely follows the contours of the brain
95
what are sulci and gyri?
sulci are valleys of the brain
| gyri are hills of the brain
96
what is the pathway of flow of CSF in the brain?
lateral ventricle -> 3rd -> cerebral aqueduct -> 4th -> arachnoid granulations -> venous sinuses -> venous blood -> drained from head
97
where and how is CSF produced?
produced in the choroid plexus by separating from blood
98
what is hydrocephalus and why does it occur?
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
what are the parts of the frontal lobe?
pre-frontal cortex, pre-motor cortex, and motor cortex
100
what are each of the regions of the frontal lobe involved in?
pre-frontal cortex- deciding action and anticipation of consequence
pre-motor cortex- planning movement
motor cortex- execution of movement
101
what is the frontal lobe involved in?
voluntary motor functions
102
what is the parietal lobe involved in?
sensory functions
103
what is the name of the part of the parietal lobe that receives sensory information?
somatosensory cortex or primary sensory cortex
104
where is the somatosensory cortex located?
post central gyrus
105
what is the occipital lobe involved in?
it is the primary visual centre of the brain
106
what is the temporal lobe involved in?
hearing and short-term memory
107
what are the main sulci in the brain? where are they located?
central sulcus- separates frontal and parietal lobes
parietal-occipital salcus
lateral sulcus- separates the temporal lobe from the parietal and frontal lobes
108
what are the main gyri in the brain?
pre-central gyri
post-central gyri
- both are in relation to the central sulcus
109
what is the main fissure in the brain? where?
transverse fissure
| - separates the cerebellum and the cerebral cortex
110
what is the structure of the brainstem?
consists of the midbrain, pons, and medulla oblongata
111
what are the 3 types of white matter in the cerebral cortex?
commissural tracts, projection tracts, and association tracts
112
what communication do commissural tracts allow?
allow communication between both sides of the cortex
113
what communication do projection tracts allow?
communication between cortex and other region of CNS
114
what communication do association tracts allow?
communication between one area of cerebral cortex and another
115
what information does the corticospinal tract involve?
somatic efferent information
116
what does the cerebrum consist of?
the cerebral cortex and corpus callosum
117
what is the structure of the cerebral cortex?
outer layer of grey matter, inner layer is white matter
118
what is the pathway for motor information to travel from the primary motor cortex?
- 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
what is the function of the cerebellum?
to coordinate movement by comparing intended movement to actual movement and alerting brain to respond to discrepancies
120
what are the basal ganglia/basal nuclei/deep nuclei?
are a collection of cell bodies in the CNS deep inside the brain
121
what is the function of the basal ganglia?
are involved in modifying movement and helping to select, initiate, and terminate movement
122
what is a disease associated with malfunction of the basal nuclei?
parkinson's disease
123
what causes parkinson's disease?
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
what is the process of an action potential getting generated in a neuron?
- 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
how is the action potential conducted along the axon?
by electric fields from action potential in one region of the membrane activating adjacent voltage gated Na+ channels
126
what is the refractory period?
the amount of time it takes until another action potential can happen
127
what are the types of refractory period?
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
what is the absolute refractive period? when does it occur during the action potential generation process?
- 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
what is the relative refractory period? when does it occur during action potential generation?
- 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
what are the things that determine the speed of the action potential?
- myelinated axons
- diameter of axon
- refractory period
131
how do myelinated axons increase the action potential conduction speed?
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
what are the types of synapses?
chemical synapse and electrical synapse
133
what are the differences between electrical synapse and chemical synapse?
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
describe the process of signal transmission in neuron 1
- 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
describe the process of synaptic transmission in neuron 2
- 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
what occurs during synaptic transmission when Na+ channels are activated?
- 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
what occurs when Cl- channels are activated during synaptic transmission?
- activation of Cl- channels causes Cl- to flow into the cell
- flow of Cl- causes hyperpolarisation in the cell
138
what is the effect of depolarisation on the post synaptic neuron? what is the term for this?
- depolariation is excitatory
| - the temporary depolarisation of the post synpatic membrane is called the excitatory post synaptic potential (EPSP)
139
what is the effect of Cl= on the post synaptic neuron? what is the term
- Cl- flowing into the cell causes hyperpolarisaton
- hyperpolarisation is inhibitory
- this is called inhibitory post synaptic potential (IPSP)
140
in synaptic transmission, how are the ways that the signal can be stopped?
- 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
what is an ionotropic receptor?
a receptor that causes the opening of a channel once bound by a neurotransmitter
142
what is a metabotropic receptor
a receptor which acts through a second messenger system
143
what are the main types of neurotransmitter?
excitatory (EPSP)
- cause depolarisation
inhibitory (IPSP)
- causes hyperpolarisation
144
what are some examples of excitatory neurotransmitters?
- acetylcholine
| - glutamate
145
what is an example of inhibitory neurotransmitters?
GABA
| gamma amino butyric acid
146
where is acetlycholine used? what effect does it have? type of receptor?
- neuromuscular junction (for muscle contraction) and brain
| - it activates stimulus-gated Na+ channels
147
where is glutamate used? what effect does it have? type of receptor?
- most common excitatory neurotransmitter in CNS
- activates stimulus-gated Na+ and Ca2+ channels
- no receptor information given
148
where is GABA used? what effect does it have? type of receptor?
- most common inhibitory neurotransmitter in the brain
- activates Cl- and K+ channels
- Cl- channels are ionotropic K+ channels are metabotropic
149
what is the threshold frequency?
about -59mV
150
what spatial summation?
the addition of excitatory and inhibitory inputs that arrive at different synaptic knobs
151
what is temporal summation?
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
what are the types of synaptic network?
- divergence
| - convergence
153
what are the advantages of a divergent synaptic network?
- allows signal to be amplified
| - allows for coordination of information between different areas of the brain
154
what are the advantages of a convergent synaptic network?
- 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
what are the stages of muscle contraction?
excitation
contraction
relaxation
156
what does the excitation stage of muscle contraction involve?
- 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
what does synaptic transmission involve?
- 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
what does the contraction stage of muscle contraction involve?
- 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
what is involved in the process of relaxation in muscle contraction?
- 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
what is a twitch?
a single muscle contraction caused by a single action potential in a single motor unit
161
how are twitches caused?
repeated stimulus with a certain time interval between stimuli, causes contractions with increasing levels of tension
162
why do contractions in twitches having increasing levels of tension?
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
what are the stages of a twitch?
latent period, contraction phase, and relaxation phase
164
what is treppe?
the effect that a series of spaced twitches increases the tension of contraction more than just a single twitch
165
what is tetanus and what condition must be in place for it to occur?
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
what are the types of tetanus and what makes them different?
incomplete tetanus
- fluctuations between individual twitches is visible
complete tetanus
- fluctuations not visible
167
why does tetanus occur?
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
what are the energy sources required for muscle contraction?
ATP and CP (creatine phosphate)
169
what is the role of ATP?
-it is the structure which delivers energy (provides all energy for skeletal muscle contraction)
170
how long can the store of ATP we have in our bodies sustain a contraction for?
limited store of ATP
| =maximum contraction of skeletal muscles for 2-4s
171
what is CP? what is its role?
creatine phosphate
| - in skeletal muscles as a back up system for ATP
172
how does CP perform its function?
it is broken down and the energy generated is used to convert ADP back into ATP
173
how long can the store of CP we have in our bodies sustain a contraction for?
limited store of CP
| = can make enough ATP to sustain contraction for 20s
174
what is the back up system to ATP and CP?
metabolism of food
175
when is energy required during muscle contraction? why?
- only during the relaxation period
| - because energy is required to pump Ca2+ back into the SR and to detach myosin from actin
176
what is rigor mortis?
muscle stiffness that occurs after body has run out of energy (ATP)
177
why does rigor mortis occur?
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
what is the oxygen binding protein in muscles? how many oxygens can it bind?
myoglobin
| can bind one oxygen
179
what are the types of muscle fibre? include all their names (3)
- red/slow/type I
- intermediate/type IIa
- white/fast/type IIx
180
what are some of the features of red muscle fibres? (myoglobin, metabolism, diameter, speed. energy consumption, sustained)
- 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
features of white muscle? (myoglobin, metabolism, diameter, speed. energy consumption, sustained)
- 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
what is an example of a muscle made up of slow muscle fibres?
soleus
183
what is an example of a muscle made up of type IIx muscle fibres?
internal rectus
| -the muscle in the eye
184
what is the effect of strength training on muscle physiology?
-hypertrophy
more sarcomeres produced so
-muscles get bigger
-more anaerobic metabolism
185
what is the effect of endurance training on muscle physiology?
-increase blood supply to muscle
-more blood vessels
-more mitochondria
-more aerobic enzymes
thus improved aerobic metabolism
186
what is the effect of disuse on muscle physiology?
-atrophy
sarcomeres are broken down so
-smaller muscles
-less power
187
what is fatigue? cause?
a state of exhaustion
- loss of strength or endurance
- caused by strenuous muscle activity
188
what are the types of fatigue?
physiological fatigue
| psychological fatigue
189
what is physiological fatigue?
there is an ATP depletion
| build up of metabolic by-products (Pi and lactic acid)
190
what is psychological fatigue?
feedback from working muscle to brain which produces sensation of fatigue, even though still capable of contracting
(feed forward)
191
what are the functions of each of the muscle types?
```
skeletal
- movement
- heat
- posture
cardiac
- pump blood
smooth
- movement of contents of viscera
```
192
what is the structure of cardiac muscle?
consist of branching network of myocytes that are connected by intercalated discs
193
what are intercalated discs? what features do they give to the muscle type they are associated with?
- 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
what is the structure of smooth muscle?
consist of spindle-shaped cells
no sarcomeres
-has dense bodies located randomly, which are connected by myofilaments
195
what is the contraction of smooth muscle like? why?
contraction occurs in all directions and is weaker
| -this is because the myofilaments are arranged in all directions
196
what are the types of smooth muscle cell and how are they different? what about their structure makes them different?
-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
how does smooth muscle achieve vasoconstriction and vasodilation?
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
how is the muscle contraction of smooth muscle different to the muscle contraction of skeletal muscle?
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
muscle types - striations?
skeletal - striated
smooth - no striated
cardiac - striated
200
muscle types- AP spread from cell to cell?
skeletal - no
smooth - yes(single-unit)
smooth - no(multi-unit)
cardiac - yes
201
what does syncitium mean?
muscle works as a whole
202
muscle types- control?
skeletal- voluntary
smooth - involuntary
cardiac - involuntary
203
muscle types- speed of contraction?
skeletal - fast
smooth - very slow
cardiac - slow
