Nerves + Muscles Flashcards
1
Q
What is the anatomical organisation of the nervous system?
A
- Central nervous system: brain + spinal cord
- peripheral nervous system:
1. Autonomic ns = sympathetic ns, parasympathetic ns + enteric ns
- Somatic nervous system
2
Q
What is the large section of the brain called?
A
- Cerebrum
3
Q
What is the smaller section of the brain called?
A
- Cerebellum
4
Q
What is the meninges?
A
- The three membranes that align the skull and enclose the brain + spinal cord (dura mater, archanoid + pia matter
5
Q
What is the gyrus + sulcus?
A
- G= Ridge in brain
- s= groove in between ridges
6
Q
Lobes of the cerebrum
A
- Frontal lobe
- temporal lobe
- parietal lobe
- occipital lobe
7
Q
Parts of the brainstem:
A
- Midbrain
- pons
- medulla oblongata
8
Q
Parts of the forebrain
A
- Cerebrum
- diencephalon: hypothalamus, thalamus
9
Q
How many pairs of spinal neves are there?
A
- 31
10
Q
How are the spinal nerves separated?
A
- 8 clerical: neck, shoulders + arms
- 12 thoracic: chest + abdomen
- 5 lumbar: hips + legs
- 5 sacral: genitalia & gastrointestinal tract
-1 coccygeal
11
Q
Grey matter vs white matter:
A
12
Q
Morphology of neurons?
A
- Afferent (sensory): bipolar + pseusunipolar
- interneurons: multipolar
- efferent (motor) neurons: multipolar
13
Q
What are the types of glia?
A
-Astrocytes
- oligodendrocytes
- microglia
- ependymal cells
14
Q
Function of astrocytes
A
- Maintain external environment for neurons (lots of sticky hands)
15
Q
Function of ogliodendrocytes
A
- Form myelin sheaths in CNS
16
Q
Function of microglia
A
Macrophages of CNS, hoover up infection
17
Q
Function of ependymal cells
A
- Produce the cerebrospinal fluid
18
Q
3 membrane potentials
A
- Action
- graded
- resting membrane
19
Q
Properties of graded potentials
A
- graded (small stimuli = small response)
- decremental (smaller as they travel along the membrane) - depolarising or hyper polarising
- summate (two smau individual graded potentials can added together)
20
Q
What is the role of graded potentials
A
- Decide when an action potential is fixed
21
Q
Ionic basis of graded potentials
A
- EPSPs generated by opening na/k channels or closing leaky K channels
- ISPs generated by opening Cl channels or opening K channels
22
Q
How is an action potential generated?
A
- Voltage gated Na channels mediating the depolarising phase
- voltage gated K channels mediating the repolarising and hyperpolarising phase
23
Q
Properties of action potentials
A
- Have a thresh hold call or none)
- self propagating
- have a refractory period
- travel slowly
- mediated by voltage gated channels
24
Q
Nerve fibre types (properties)
A
- Not all axons are made equal
- several classifications
- small and large unmyelinated and myelinated axons
- All conduct at different velocities
- generates compound action potential
25
What are conduction velocities?
The speed at which an electrochemical impulse propagates down a neural pathway
26
What are conduction velocity relationships to fibre types?
The larger the diameter of nerve fibres the faster the conduction velocity
27
Consequence of demyelinating diseases
- Demyelination in the CNS = multiple sclerosis, in the PNS = Guillain-Barré syndrome
- decrease membrane resistance (more current leaks out membrane)
- more current wasted charging up membrane
- conduction fails
28
Structure of neuromuscular junction
- Presypnatic terminal filled with vesicles containing acetylcholine,
- synaptic cleft
- postsynaptic end plate of skeletal muscle fibre
- folds at end of planet
29
Process of neuromuscular transmission
1. Action potential in motor neuron
2. Opens voltage-gated Ca2 Chanels in pre-synaptic terminal
3. Fusion of vesicles
4. ACh diffuses across synaptic cleft
5. ACh binds to ACh receptors
6. Opens ligand gated channels
7. Evokes graded potential (end plate potential)
8. Depolarises membrane to threshold
9. Opens voltage gated Na channels
10. Evokes action potential
11. Muscle contracts
12. Acetylcholine cleared up by acetylcholinesterase
30
Ultrastructure + functions of synapses between neurones
- Same as neuromuscular junction Just more complex
Anatomical arrangement: Axo-dendritic, Axo-somatic and Axo-axonal
31
Processes of synaptic transmission in CNS
- Divergence, convergence, feedback inhibition (prevents repeated firing)
- neurotransmitters: Amines, amino acids, peptides, purines, gases
- postsynaptic potentials: fast/slow EPSP/IPSP
32
Role of synapses integration of neuronal function
- hundreds of executor or inhibitory synapses, these evoke slow/fast EPSPs/IPSPs (each only a few mV high)
- adding together either pushes cell to fire action potential or keeps cell away from threshold to stop it
33
Common excitatory + inhibitory neurotransmitters
- Acetylcholine
- amines
- Amino acids
- peptides
- purines
- gases
34
Basic properties of signal transduction in neurons
- Use protein kinases
- use secondary messengers
- depend on the interactions of proteins and other molecules
- most be properly terminated to carry out their function
35
What is meant by the terms EPSP and IPSP?
- EPSP: generated by opening na/k channels or closing leaky K channels
- IPSP: generated by opening cl channels or opening K Chanels
36
Process of excitation-contraction coupling
1. Muscle action potential propagated
2. Ca released from lateral sac
3. Ca binding to troponin removes blocking action of tropomyosin
4. Cross bridge moves
5. Ca taken up
6. Ca removal from troponin restores tropomyosin blocking action
37
Types of muscle
-Striated: skeletal (voluntary muscles, diaphragm) + cardiac
-smooth: (blood vessels, airways, uterus)
38
isometric vs isotonic twitches
- Isometric: contraction with constant length
- isotonic: contraction with showering length
39
Sliding filament theory-muscle contraction
1. Cross bridge binds to actin
2. Cross bridge moves
3. ATP binds to myosin causing cross-bridge to detach
4. Hydrolysis of ATP energises cross-bridge
40
Sliding filament theory in relation to length tension properties of muscle
41
Generation of controlled force by recruitment of motor units.
Forces exerted by muscle = tension
Forces exerted on muscle = load
42
Explain Tetanus
- APs is 1-2ms long (twitch can last up to 100Ms)
- more APs during contraction this can add up = summation
43
Explain fatigue
- High intensity: conduction failure due to high potassium (depolarisation),
- during long-term, low intensity exercise: low muscle glycogen, blood glucose, dehydration
- cerebral cortex cannot excite motor neurons
44
Aerobic properties of muscle
45
Anaerobic properties of muscle
- More fast twitch fibres
46
Structure of smooth muscle
- Single or multiunit smooth muscle
- No striations
- innovated by ans
- finale shaped
- thick myosin and thin actin filaments '
47
Function of smooth muscle
- Contraction and tension
48
Contraction and relation in smooth muscle
49
Explain how differences in elastic properties of muscles contribute to force production
