Physiology Flashcards
(147 cards)
1
Q
a _____ supplies all the fibres of one motor unit
A
single alpha motor neuron
2
Q
muscles that have fine movements have more/fewer fibres per motor unit
roughly = ___ fibres
A
fewer
10
3
Q
muscles that are for power have __fibres per motor unit
A
100-1000s
4
Q
organisation of muscle:
sarcomere>____>muscle fibre> ____>whole muscle
A
myofibril
motor unit
5
Q
skeletal muscle:
___ initiation and propagation involves ___+neuromuscular junction with ____
excitation contraction coupling by ___ entirely from ___
A
neurogenic
motor units
with Nitrogen Oxide gap junctions
Ca2+ entirely from sarcoplasmic reticulum
6
Q
gradation of contraction in skeletal muscle is due to ___+___
A
motor unit recruitment and summation of contractions
7
Q
in skeletal muscle Ca2+ is released from ___ of ____ when surface AP spreads down ____ => ______
A
lateral sacs of sarcoplasmic reticulum
T/transverse tubules
excitation-contraction coupling
8
Q
in skeletal muscle:
Ca2+ binds to ___ which causes ___ to be pulled away from actin binding site so it can bind to myosin
A
troponin
tropomyosin
9
Q
Z line to next Z line =
A
sacromere
10
Q
skeletal muscle:
ATP in contraction is for ___
in relaxation it ___
A
contraction = power cross bridges relaxation = release cross bridge and pump Ca2+ into sarcoplasmic reticulum
11
Q
____ muscle unit recruitment during ___ contractions help prevent skeletal muscle fatigue
A
asynchronous
submaximal
12
Q
gradation of tension in skeletal muscle fibres depends on __+__
A
number of muscle fibres contracting
tension developed by each muscle fibre
13
Q
tension developed by one skeletal muscle fibre depends on … (4)
A
thickness of fibre
length of fibre
freq of stimulation
summation of contractions
14
Q
The AP in skeletal muscle is __+___ meaning it is possible to summate twitches to bring about __ contraction through ___ stimulation of fibres
A
shorter than resulting twitch + no refractory period
stronger
repetitive fast
15
Q
if a skeletal muscle is constantly stimulated before it can relax = ___ = ____ contraction
A
tetanu
maximal sustained contraction
16
Q
optimum length of skeletal muscle =
at this length ___ can be acheived
A
resting length of the muscle
maximal tetanic contraction
17
Q
2 types of skeletal muscle contraction
A
isotonic
isometric
18
Q
isotonic contraction in skeletal muscle =
used for:
A
tension constant as length changes
body movement + moving objects
19
Q
isometric contraction in skeletal muscle =
used for:
A
tension develops at constant muscle length
support objects in fixed position + maintain body posture
20
Q
velocity of skeletal muscle shortening ____ as load increases
A
decreases
21
Q
3 types of skeletal muscle fibre
most motor units contain more than one kind
A
slow oxidative type 1/slow twitch
fast oxidative type IIa / intermediate twitch
fast glycolytic type IIx / fast twitch
22
Q
Metabolic pathways that supply ATP in skeletal muscle fibre = (3)
A
transfer of high E phosphate from creatinine phosphate to ATP - immediate ATP source
oxidative phosphorylation (main aerobic source)
glycolysis (main anaerobic source)
23
Q
main differences between the 3 types of skeletal muscle fibres
A
enzymatic pathways for ATP synthesis
resistance to fatigue
activity of myosin ATPase
24
Q
activity of myosin ATPase determines ______ in skeletal muscle fibres
A
the speed of energy availability for cross bridge formation ie speed of contraction
25
resistance to fatigue in skeletal muscle fibres is increased if ____
they have a greater capacity for ATP synthesis
26
slow oxidative type 1 (slow twitch) fibres are for ___
prolonged low-work aerobic activity eg. walking/posture
27
fast-oxidative type IIa (intermediate twitch) fibres have ___+__ metabolism for ___
aerobic and anaerobic
| prolonged moderate work eg. jogging
28
fast glycolytic type IIx (fast-twitch) fibres have __ metabolism for ___
anaerobic
| short term high intensity activity eg. jumping
29
myosin ATPase activity in the 3 types of skeletal muscle fibres =
slow = low
| intermediate and fast = high
30
speed of contraction in the 3 types of skeletal muscle fibres =
slow = slow
| int + fast = fast
31
resistance to fatigue in the 3 types of skeletal muscle fibres =
```
slow = high
int = int
fast = low
```
32
oxidative phosphorylation capacity in the 3 types of skeletal muscle fibres =
```
slow = high
int = high
fast = low
```
33
enzymes for anaerobic glycolysis in the 3 types of skeletal muscle fibres =
slow = low
int =int
fast = high
34
number of mitochondria and capillaries in the 3 types of skeletal muscle fibres =
```
slow = many
int = many
fast = few
```
35
myoglobin content in the 3 types of skeletal muscle fibres =
```
slow = high
int = high
fast = low
```
36
color of fibre in the 3 types of skeletal muscle fibres =
slow + int = red
| fast = white
37
glycogen content in the 3 types of skeletal muscle fibres =
```
slow = low
int = int
fast = high
```
38
simplest form of coordinated movement
| a stereotyped response to specific stimulus
reflex
39
simplest monosynaptic spinal reflex =
| describe it
stretch reflex
| -ve feedback to resist stretch and maintain optimum skeletal muscle length
40
in stretch reflex:
___ stretched causing increased __ in ___ > synapse at ___ > __
coordinated by simultaneous __
```
muscle spindle
firing in afferent neurons
alpha motor neurons
muscle
simultaneous relaxation of antagonistic muscle
```
41
in knee reflex:
spinal segment =
peripheral nerve =
L3 +4
| femoral
42
in ankle reflex:
spinal segment =
peripheral nerve =
S1 +2
| tibial
43
in biceps reflex:
spinal segment =
peripheral nerve =
C5+6
| musculocutaneous
44
in brachioradialis reflex:
spinal segment =
peripheral nerve =
C5+6
| radial
45
in triceps reflex:
spinal segment =
peripheral nerve =
C6+7
| radial
46
sensory receptors for stretch reflex
muscle spindle
47
muscle spindle = ___ collection
specialised muscle fibre
48
muscle spindles are made up of __ fibres
| normal fibres in skeletal muscle =
intrafusal
| normal = extrafusal
49
muscle spindles are found in ___ and parallel to __
muscle belly
| extrafusal fibres
50
sensory nerve endings in muscle spindles are know as
annulospiral fibres
51
discharge from ___ in muscle spindles ___ as muscle is stretched
annulospiral fibres increases
52
efferent supply to muscle spindles =
| adjust level of __ in spindles so ___ when muscle shortens during contraction
gamma motor neurons
tension
maintain sensitivity
53
the contraction of intrafusal fibres does/doesn't contribute to the overall strength of muscle contraction
doesn't
54
in congenital myopathies: ___ changes => decreased ___
microscopic
| contractile ability
55
muscular dystrophy = ____ of contractile elements
chronic degeneration
56
myotonia is an example of an abnormality in ___
muscle membrane ion channels
57
4 broad types of acquired myopathies
inflammatory
toxic
endocrine
non-inflam
58
delayed relaxation after voluntary contraction =
myotonia
59
EMG aka
detects ___
differentiates ___ from ___
usually do __ at same time as this test is not pathognomic
electromyography
presence of muscle activity - freq and amplitude of APs
primary muscle disease from weakness due to neurological disease
nerve conduction study
60
5 useful tests in neuromuscular disease
```
muscle biopsy
EMG
inflam markers
muscle enzymes
nerve conduction studies
```
61
motor neuron branches end in a ___ at NMJ
terminal bouton
62
the cell body of motor neurons is in ____
the ventral horn of the spinal cord (or brain stem)
63
motor neurones release ___ at NMJ which activates ___ a ___ of glycoprotein subunits ((α1)2β1δε) - in embryonic muscle ε is replaced by _
ACh
Nicotinic ACh post-synaptic receptors
pentamer
γ
64
Nicotinic ACh post-synaptic receptors in muscles are closed unless ____ and then they are ___ selective
2ACh bind
| cation selective
65
Nicotinic ACh post-synaptic receptors in muscles are roughly equally permeable to __+__
direction of movement?
which one has a larger driving force and causes depolarisation (___)
Na+ in to muscle cell + K+ out
| Na+ > driving force => end plate potential / epp
66
each ACh vesicle contains one ___ of ACh
| the electrical response to one vesicle's ACh =>___
quantum
| mepp (miniature end plate potential)
67
```
End plate in muscles have ___ adjacent to Nicotinic ACh post-synaptic receptors
function = ___
```
voltage-activated Na+ channel
| AP propagates from the endplate over the length of the muscle fibre without deteriorating
68
bouton synapse at the ____ of skeletal muscle fibre
endplate region
69
APs propagate over the surface membrane (____) of skeletal muscle fibre and enters ____
this causes _____ from ___
sarcolemma
transverse (T) tubules
Ca2+ from the sarcoplasmic reticulum
70
termination of AP in muscle cells:
| ___ hydrolyses __>choline(__) + acetate (___)
AChE - ACh
taken up into transporter
diffuses from cleft
71
terminal bouton is surrounded by ___
Schwann cell
72
ACh vesicles at NMJ await release at "___"
active zones
73
choline is recycled in the pre synaptic bouton:
| choline + ___ > (enzyme) > ACh
acetyl Co-A
| CAT
74
the location of nicotinic ACh receptors in muscle cells
end plate
75
neuromyotonia aka __/_
s+s
usually acquired = ___ against ____ in motor neurone => ____
NMT/ Isaac's syndrome
cramps, stiffness, myotonia (slow relaxation), fasciculations (twitches)
AI Ig - voltage activated K+ channels - hyperexcitability
76
Rx for neuromyotonia/Isaac's syndrome
anticonvulsants - eg carbamazepine, phenytoin
| they block Na+ channels and may also increase inhibitory GABA
77
v rare and ass with small cell lung ca => muscle weakness
Lambert-Eaton Myasthenic Syndrome (LEMS)
78
AI process in Lambert-Eaton Myasthenic Syndrome (LEMS)
Ig against Ca2+ channels in neurone terminal => decreased Ca2+ entry and ACh release
79
Rx of Lambert-Eaton Myasthenic Syndrome (LEMS)
anticholestinesterases (pyridostigmine)
| K+ channel blockers (3,4 - diaminopyridine)
80
___ muscle weakness can transiently improve on exertion, ____ is progressive muscle weakness during activity
```
Lambert-Eaton Myasthenic Syndrome (LEMS)
Myasthenia Gravis (MG)
```
81
AI mechanism behind Myasthenia Gravis
Ig against nicotinic ACh receptors => decreased epp amplitude
82
Rx for myasthenia gravis =
antichloniesterases - edrophonium (to diagnose), pyridostigmine (long term)
IS eg azathioprine
83
very potent toxin that irreversibly inhibits ACh release at NMJ
no Rx, just time, v high mortality rate
Botulinum Toxin
84
low dose botulinum haemoglutin complex IM is used for ___ eg __+__
dystonias - strabismus/blepharospasm
85
To induce reversible paralysis in Sx = ___ compounds eg __/__
they interfere with ____ as antagonise ____ and decrease ___
```
curare-like
vecuronium
atracurium
post-synaptic ACh
nicotinic ACh receptors
epp amplitude
```
86
synarthosis =
fibrous joints
87
amphiarthrosis =
| egs (4)
cartilaginous joints
| IV discs, pubic symphysis, part of SIJ, costochondra
88
diarthrosis =
synovial joint
89
synovial membrane lines ____
| it is a __ CT with ___ networks and ___ ; they contain ___ that produce ___
```
fibrous capsule in synovial joints
vascular CT
capillary networks
lymphatics
synovial cells (fibroblasts) => synovial fluid
```
90
>1 pair of articular surfaces in a synovial joint = a ___ joint
compound
91
most of the stress across a synovial joint is taken up by __+__
tendons and muscles across the joint
92
joint lubrication at diarthroses = (3)
cartilage interstitial fluid
synovium
synovium-derived lubricin-glycoprotein
93
synovium is derived from ___(__) a polymer of __
```
hyaluronic acid (mucin)
disaccharides
```
94
function of synovial fluid
lubrication
supplies chondrocytes with O2 and nutrients
removes CO2 and waste
95
high viscosity of synovial fluid is due to ___
| viscosity varies with ___ as does elasticity
mucin
| joint movement
96
other constituents of synovial fluid eg. uric acid are derived by ___
dialysis of blood plasma
97
normally synovial fluid contains a few cells - mainly ___
mononuclear luecocytes
98
rapid movement at a synovial joint => synovial fluid viscosity ___ and elasticity ____
is defective in ___
viscosity decreases
elasticity increases
diseased joint eg OA
99
colour of synovial fluid in trauma
red
100
colour of normal synovial fluid and in an inflammatory joint
```
norm = colourless
inflam = straw yellow
```
101
clarity of synovial fluid normally, in inflammation and in septic joint
```
norm = transparent
inflam = translucent
septic = opaque
```
102
WBC count (/mm^3) in synovial fluid normally, in inflammation and in septic joint
```
norm = <200
inflam = 2000-75000
septic = >100,000
```
103
PMN leucocytes (/mm^3) in synovial fluid normally, in inflammation and in septic joint
```
norm = <25
inflam = >50
septic = >75
```
104
zones in articular cartilage superficial to deep =
| differ in their ___ and ___
superficial > middle > deep(all chondrocytes) > calcified zone
organisation of collagen fibres
content of cartilage components
105
usually articular cartilage is __ cartilage
hyaline
106
articular cartilage has special ___ : 70% ___, 20% ___, 10% ___
ECM
70 water
20 type II collagen
10 proteoglycans
107
properties of water in articular cartilage (3)
```
uneven distribution (80% near art. surface)
decreases with age
maintains tissue resilience
```
108
properties of type 2 collagen in articular cartilage (2)
decreases with age
| provides stiffness and strength
109
```
proteoglycan in articular cartilage:
high concn in __+__ zone
composed mainly of __ eg ___
__ changes with age eg decreased amount of ___
function =
```
middle and deep
glycosaminoglycan eg chondroitin sulfate
composition - condroitin decreases
compression for load bearing
110
degradation of ECM in articular cartilage is by ___ from chondrocytes eg __+__
metalloproteinase proteolytics
| collagenase + stromelysin
111
98% of articular cartilage volume =
| maintained degraded, synthesised and organised by __
ECM
| chondrocytes
112
chondrocytes get nutrients and O2 from __
synovial fluid
113
catabolic factors in articular cartilage matrix turnover (2)
TNFα + IL-1
| => stimulate proteolytic enzymes and inhibit proteoglycan synthesis
114
anabolic factors in articular cartilage matrix turnover (2)
TGF-β and IGF-1
| =>stimulate proteoglycan synthesis and counteract IL-1 effects
115
markers of articular cartilage degradation = increased __+___
____ in synovial fluid
serum and synovial keratin sulfate (^ in age and OA)
| type 2 collagen (RA + OA)
116
pain definition =
an unpleasant sensory and emotional experience associated with actual tissue damage or described in terms of such damage
117
nociceptive pain is ___ (early warning sign) and ___ (only to intense stimuli)
adaptive
| high threshold
118
___ overrides other nervous system activities eg. => withdrawal reflex
nociceptive pain
119
nociceptors = specific _____ activated by ___ stimuli.
are ___ order and relay to ___ at __ synapse
stimuli =__/__/__
peripheral primary sensory afferent neurones
intense noxious
1st order - 2nd order - CNS
temp / mechanical force / chemical irritants
120
inflammatory pain is __(early warning system) +__
caused by activation of ___
=> ___+___
adaptive + protective
immune system to injury/infection
pain hypersensitivity and allodynia
121
inflammatory pain discourages __+___ so aids healing
physical contact and movement
122
maladaptive pain = ___ pain
due to _____
2 types =
=> __/___
```
pathological
abnormal nervous system functioning
neuropathic (neural lesion +/- symptoms)
dysfunctional (no neural lesion but +ve symptoms)
spontaneous pain/pain hypersensitivity
```
123
Congenital insensitivity to pain (CIP) is caused by which mutation? that encodes __ which is highly expressed in nociceptive neurones
loss of function (missense/inframe deletions) in SCN9A
| voltage gated activated Na+ channel (NaV1.7)
124
nociceptors are comprised of __+__ fibres
Aδ + C
125
Aδ fibres = __/___ nociceptors - ___ myelinated
| mediate __/__ pain
mechanical / thermal
thinly
1st / fast
126
C fibres are ___ (respond to all noxious stimuli) and ___ so mediate __/__ pain
polymodal
| unmyelinated - 2nd/slow
127
thermal stimuli to C fibres activate ____ esp. ___ - it is greatly sensitised in inflammation and so becomes active at ___
Transient receptor potential family (TRP)
esp. TRPV1
body temperature
128
in chemical stimulation of C fibres:
H+ activates ___
Atp activates ___
bradykinin activates ____
ASIC (acid sensing ion channels)
P2X+ P2Y receptors
B2 receptors
129
possible receptor to mechanical stimuli in C fibres
Piezo2
130
all stimulation of c fibre receptors cause __/__ influx > graded ___ > ___ activated > aP to CNS
Na+ Ca2+
depolarisation
voltage gated Na+ channels
131
amplitude of depolarising receptor/generator potential in C fibres is __ and proportional to ___
graded
| stimulus intensity
132
local current flow (___) in c fibres trigger all/none APs at frequency proportional to ___
Hermann currents
| receptor potential
133
axon of 1st order neurone nociceptor synapses in _____
its soma is in ____/____
axon of 2nd order neurone > ___+___ > pain
ducussation via ____ occurs at all levels of the spinal cord
dorsal/posterior horn of spinal cord
dorsal root ganglion (DRG) / trigeminal ganglion (TG)
spinothalmic + spinoreticulothalmic tracts
ventral white commisure
134
subset of C fibres = ___ polymodal nociceptors
afferent - release __+__ to CNS at dorsal horn synapse
efferent - releases ____ and contributes to ___
peptidergic
glutamate + peptides (substance P and neurokinin A)
pro-inflam mediators (eg calcitonin gene related peptide (CGRP) and substance P)
neurogenic inflam
135
neurogenic inflam:
| ___(__+__) from peptidergic nociceptor free nerve endings are released due to __/____
peptides (substance P and CGRP -calcitonin gene related peptide)
inflammatory mediators/tissue damage
136
role of substance P released in neurogenic inflammation (3)
vasodilation and extravasation of plasma proteins (promotes formation of bradykinin and PGs)
histamine released from mast cells
sensitises surrounding nociceptors
137
the role of CGRP released in neurogenic inflammation
vasodilation
138
CGRP and substance P cause effects in neurogenic inflammation that ultimately lead to ___
primary and secondary hyeralgesia and allodynia
139
in pain: primary afferent to 2nd order neurone in dorsal horn transmission =
AP > ___ influx > __ released from afferent
> __ epsp and neuronal excitation by activating ___ and some NMDA receptor involvement > depolarisation of 2nd neurone and ___ open > AP
```
Ca2+
glutamate
fast
postsynaptic AMPA receptors
Na+ channels
```
140
in pain: primary afferent to 2nd order neurone in dorsal horn transmission:
__+___ are also involved esp in high freq stimulation = __+__ epsp that facilitates ___ activation by relieving voltage dependent block by __
```
substance P
CGRP
slow and prolonged
NMDA receptor
Mg2+
```
141
for pain: primary afferent cell bodies (except in trigeminal system) are located in the ___ - axon terminates centrally in the ___ in various ___
DRG
dorsal horn
lamina Rexed
142
nociceptive C and Aδ mostly terminate in __+__ also + __ for Aδ
laminae I+II
| V for Aδ too
143
nociceptive specific cells synapse only with __+_
C and Aδ fibres
144
cells that receive input from Aβ fibres are ___
proprioceptive
145
wide dynamic range (WDR) neurones receive input from _+_+_
Aβ, C and Aδ fibres
146
in nociceptive tract for 2nd order neurones:
in spinothalmic tract:
projecting neurones from ___ (fast fibre ___ pain) terminate in ___
projecting neurones from ___ (WDR) terminate in __+__
pain perception (site and intensity) need ___ firing from both pathways
lamina I - Aδ - posterior nucleus of thalamus
lamina V - posterior and ventroposterior nucleus of thalamus
simultaneous
147
in nociceptive tract for 2nd order neurones:
in spinoreticular tract: mainly transmits ___ __ fibre pain
makes extensive connections with ___ in ___ eg periaquesductal grey (PAG) + _____
involved in ___ responses to pain, arousal, emotion and fear of pain
slow C
reticular nuclei in brainstem
parabrachial nucleus (PBN)
autonomic
