nerves and muscles Flashcards
1
Q
gross structure of the brain
A
Meninges, sulcus, gyrus, cerebellum, cerebrum (4 lobes), diencephalon (thalamus and hypothalamus), brainstem (midbrain, pons, medulla), cranial nerves
2
Q
gross structure of the spinal cord
A
Grey vs. white matter, dorsal vs. ventral horn, dorsal root ganglion, spinal nerves, spinal tracts
3
Q
describe the pairs of spinal nerves
A
31 pairs:
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
4
Q
types of neuron
A
- afferent neurons = sensory (PNS)
- interneurons = CNS
- efferent neurons = (CNS)
5
Q
describe neuron structure
A
dendrites
cell body
initial segment
axon
axon terminals
6
Q
dendrite function
A
receives information
7
Q
initial segment function
A
axon hilock triggers action potential
8
Q
cell body function
A
contains nucleus
9
Q
axon function
A
sends action potential
10
Q
axon terminal function
A
releases neurotransmitter
11
Q
oligodendrocytes function and location
A
form myelin sheath (CNS)
12
Q
astroglia function and location
A
maintain external environment for neurons and form blood brain barrier (CNS)
13
Q
microglia function and location
A
macrophages of the CNS
14
Q
ependymal cells function and location
A
produce cerebrospinal fluid (CNS)
15
Q
schwann cells function and location
A
form myelin sheath (PNS)
16
Q
The resting membrane potential is dominated by what
A
the permeability of the resting membrane to K+
17
Q
types of graded potential
A
generator potentials,
postsynaptic potentials,
end plate potentials,
pacemaker potentials
18
Q
function of graded potentials
A
Their job is to decide when an action potential is fired
19
Q
properties of graded potentials
A
Graded, decremental, depolarising or hyperpolarising, can summate
20
Q
how are EPSPs generated
A
by opening Na+/K+ channels or closing leaky K+ channels
21
Q
how are IPSPs generated
A
by opening Cl channels or opening K channels
22
Q
example of demyelinating disease in CNS
A
Multiple sclerosis
23
Q
example of demyelinating disease in PNS
A
Guillain-Barré syndrome
24
Q
structure of the neuromuscular junction
A
terminal filled with vesicles containing acetylcholine (ACh)
25
process of neuromuscular transmission.
1. action potential in motor neuron
2. opens voltage gated Ca channels in presynaptic terminal
3. fusion of veiscles
4. ACh diffuses across synaptic cleft
5. ACh binds to ACh nicotinic receptors
6. this opens ligand-gated Na/K channels
7. evokes end plate potential
8. this always depolarises membrane to threshold
9. which opens voltage gated sodium channels
10. and evokes action potential
26
examples of excitatory neurotransmitters
glutamate, epinephrine and norepinephrine
27
examples of inhibitory neurotransmitters
Gamma-aminobutyric acid (GABA), glycine and serotonin
28
what is meant by a receptor
A molecule inside or on the surface of a cell that binds to a specific substance and causes a specific effect in the cell
29
function of an agonist
mimic the normal effect of the receptor
30
affinity and efficacy of a full agonist
full efficacy and full affinity
31
affinity and efficacy of a partial agonist
full affinity and partial efficacy
32
function of an antagonist
block normal action of receptor
33
affinity and efficacy of an antagonist
full affinity and no efficacy
34
relationship between agonist concentration and effect
an agonist in the presence of a competitive agonist will reach the same response but at a slower rate due to the effect of a competitive antagonist
35
describe selective agonists
drugs that activate only some receptors
36
example of selective agonist
salbutamol - a β2 agonist
37
describe selective antagonists
drugs that block only some of those receptors
38
example of selective antagonist
propranolol - a β1 and β2 antagonist
39
where are cutaneous receptors found
distal ends of the primary sensory axon
40
what are muscle spindles
proprioceptors that consist of intrafusal muscle fibers enclosed in a sheath (spindle)
41
function of muscle spindles
spindles are stretched when the muscle lengthens
42
is skeletal muscle striated or non-striated
striated
43
what is thick filament
myosin
44
what is thin filament
actin
45
describe the sequence of excitation-contraction coupling
1. depolarization of the plasma membrane and its membrane invaginations (the t-tubular system) by an action potential
2. transduction of the depolarization signal to the sarcoplasmic reticulum membrane
3. activation of Ca2+ release from the SR and subsequent global elevation of intracellular Ca2+
4. transient interaction of Ca2+ with contractile proteins leading to muscle contraction
5. return of Ca2+ back to levels at resting conditions and muscle relaxation
46
what is tension
force exerted by the muscle
47
what is load
force exerted on muscle
48
describe isometric twitches
contraction with constant lenght
49
describe isotonic twitches
contraction with shortening length
50
describe sliding filament theory
a muscle fibre contracts when myosin filaments pull actin filaments closer together and thus shorten sarcomeres within a fibre
51
describe tetanus
When the frequency of muscle contraction is such that the maximal force is tension is generated without any relaxation of the muscle
52
is smooth muscle striated or non-striated
non-striated
53
examples of stretch reflex
patellar tendon or knee-jerk reflex
54
what reflex is mediated by golgi tendon organs
inverse stretch reflex (clasp knife reflex)
55
what nerves control GTO reflex
1b afferent nerves
56
what is ipsilateral reflex
The reflexes in which the response (reflex) occurs on one side of the body as the stimulus
57
what is contralateral reflex
reflex occurs on the opposite side of the body from the stimulus
58
what makes up the autonomic nervous system
sympathetic
enteric
and parasympathetic
59
describe the sympathetic nervous system
fight or flight
60
describe sympathetic nervous outflow
thoracic T1-12 and lumbar L1-2 regions
61
characteristics of sympathetic ganglia
- ganglia lie close to the spinal cord in the sympathetic chain or in collateral ganglia
- pre-ganglionic (mylenated) fibre is shorter than post ganglionic fibre
62
describe parasympathetic nervous system
rest and digest
63
parasympathetic nervous outflow
cranial (3, 7, 9, 10) and sacral (S2-4)
64
characteristic of parasympathetic ganglia
- ganglia lie close to or within the target
- pre-ganglionic (mylenated) fibre is longer than the post ganglionic (unmylenated) fibre
65
what are autonomic transmitters
acetylcholine
noradrenaline
66
what does acetylcholine act on
cholinergic receptors: nicotinic and muscarinic
67
what does noradrenaline act on
acts on adrenergic receptors: a and B receptors
68
sympathetic innervation of the eye
- activates a1 receptors on the radial muscle of the iris making it contract and causing the pupil to dilate
- also activates b2 receptors on the ciliary muscle which relaxes and focuses the eye far away
69
parasympathetic innervation of the eye
- activates muscarinic receptors on the sphincter muscle of the iris causing it to contract and constrict the pupil
- activates muscarinic receptors on ciliary muscle around the lens making it contract and the eye closes up
70
sympathetic innervation of the heart
- activates B1 receptors on the pacemaker cells which increases heart rate
- activates B1 receptors on the myocytes which increases strength of contraction
71
parasympathetic innervation of the heart
- activates muscarinic receptors on pacemaker cells which decreases heart rate
- little effect on myocytes which has little effect on strength of contraction
72
sympathetic innervation of the lungs
activates B2 receptors on smooth muscle of airways causing the muscle to relax and dilate the airways
73
parasympathetic innervation of the lungs
activates muscarinic receptors making smooth muscle contract and constricts airways
74
sympathetic innervation of blood vessels
- activates a1 receptors on smooth muscle of vessels causing them to contract and blood flow to decrease
- activates B2 receptors on smooth muscle of vessels causing the muscle to relax and blood flow to increase
75
parasympathetic innervation of blood vessels
usually no effect
76
how is innervation of salivary glands described
dual innervation with non antagonistic actions
77
sympathetic innervation of salivary glands
activates B receptors which stimulate thick secretion rich in enzymes
78
parasympathetic innervation of salivary glands
activates muscarinic receptors which stimulates profuse water secretion
79
sympathetic innervation of the bladder
- activates B2 receptors on smooth muscle of bladder wall which relaxes smooth muscle and reduces pressure
- activates a1 receptors on smooth muscle of sphincter which contracts the muscle and stops urination
80
parasympathetic innervation of the bladder
- activates muscarinic receptors on bladder wall causing it to contract and increase pressure
- activates muscarinic receptors on sphincter causing it to relax and causing urination
81
sympathetic innervation of the reproductive tract
activates a1 receptors on smooth muscle of urethra causing ejaculation
82
parasympathetic innervation of the reproductive tract
activates muscarinic receptors on smooth muscle of corpus cavernosum relaxing smooth muscle and causing erection
83
what is botulinum toxin used for
treating muscle spasm
used in cosmetic procedures
84
what are anti-cholinesterases used for
treating mnyasthenia gravis
reversing action of non-polarising blockers
countering botulinum poisoning
85
function of muscarinic receptor agonist
Mimic the effect of the parasympathetic system
86
function of muscarinic receptor antagonists
Block effects of the parasympathetic system
