S13- nerve and muscle

Question 1

structure of skeletal muscle

Answer 1

• 3 layers of membranes
  1. epimysium= outside layer
  2. perimysium= around fascicles
  3. endomysium= around muscle fibre
• blood vessels around fascicles

Question 2

role of smooth muscle
2 types:

Answer 2

• in airways/ vasculature/ gastrointestinal tract (in hollow organs)
• not attached to skeleton

1. phasic smooth muscle= contract rhythmically/ when activated
2. tonic smooth muscle= continously contracted (found inside sphincters-a ring of muscle surrounding and serving to guard or close an opening or tube, such as the anus or the openings of the stomach.)

Question 3

structure of smooth muscle

Answer 3

• shorter than skeletal
• NOT STRIATED
• spindle-shaped/ single/ central nucleus
• more actin then myosin= 16:1
• no sacromeres (no irganisation/no striations)
• no t-tubules/ sarcoplasmic reticulum poorly developed
• caveolae= indentations in sarcolemma= act like t-tubules

Question 4

important feature of smooth muscle is its ability to…
slower contaration because…
2 reasons for slow cycling:

Answer 4

maintain force over long periods of time (ie sphincters)
cross-bridge/ latch-bridges cycling is much slower
1. slow ATPase rate= take long for cross bridge to detach from actin filament
2. rate of Ca2+ removal from cytoplasm is slow

Question 5

skeletal and cardiac muscles are both….because of the…

Answer 5

striated
regular arrangement/ organisation of actin and myosin filaments

Question 6

structure of cardiac muscle

Answer 6

• sarcomeres
• branching
• the cells of the muscle are connecting by anchoring cell junctions= intercalated disks

Question 7

3 types of cell junctions in intercalated disc:

Answer 7

1. Fascia/ zonula adherens
2. desmosomes/ macula adherens= chemical/ mechanical coupling
3. gap junctions= electrical coupling

Question 8

a motor unit is made of

Answer 8

motor neurone + muscle unit

Question 9

summary of action potential graph

Answer 9

1. resting potential: at -70 (Na+/K+ pump)
2. stimulus reaches threshold at -55
3. depolarisation to +40 (Na+ in)
4. repolarisation (k+ out)
5. hyperpolarisation (forms the refractory period)

Question 10

difference between skeletal and cardiac contraction

Answer 10

skeletal= faster= larger diameter of fibres
cardiac= slower contraction =gap junctions= small diameter of fibres

Question 11

summary of cardiac action potential

Answer 11

phase 4= resting potential (-90)
phase 0= depolarisation (+30)= Na+ and Ca+ in
phase 1= slight repolarisation= K+ out
phase 2= the plateau Ca+ in and K+ out (exchange of charge)= L-type Ca+ channels/ slow Ca+ channels used
phase 3= repolarisation= K+ out

Question 12

Anti-arrhythmic drugs are designed to treat
the 4 classes of drugs are…and they act on different…

Answer 12

an abnormality of the heart rhythm
1. Sodium-channel blocker= phase 0
2. beta blocker= phase 4 (on K+ channel that takes K+ out)
3. potassium channel blocker= phase 3
4. Calcium channel blocker= phase 2

act on different parts/ phases/ channels in action potential graph

Question 13

2 types of diseases that affect muscles

Answer 13

1. rhabdomyolysis= breakdown of skeletal muscles and release content into circulation
2. Duchenne Muscular Dystrophy (DMD)= motor unit disease (muscle or motor neurone could be affected= x-linked)

Question 14

identify different parts of a neurone

Answer 14

1. dendrite
2. cell body and nucleus
3. Axon
4. Myelin sheath
5. node of ranvier
6. schwann cell (in myelin sheath)
7. axon terminal

Question 15

3 types of structure of neurones

Answer 15

1. multipolar= lots of branching from the cell body
2. bipolar= 2 branches from cell body
3. unipolar= one branch from cell body (ie: sensory neurone)

Question 16

the nervous system can be classified into 2 types:

Answer 16

1. Central= brain and spinal cord
2. peripheral= autonomic (sympathetic and parasympathetic) and somatic (carries sensory info)

Question 17

the brain has grey matter which consists of….and white matter which consists of…

Answer 17

1. lots of synapses and cell bodies
2. lots of axons and myelin sheath

Question 18

3 membranes/ meninges that overlie the brain and spinal cord are:

the clinical relevance includes:

Answer 18

from outer to inner
1. dura mater
2. arachnoid mater
3. pia mater

infection= meningitis
Bleeds
tumours= meningioma

Question 19

the spinal cord has…
and they are divided into 5 sections

Answer 19

31 pairs of spinal nerves
1. cervical
2. Thoracic
3. lumbar
4. sacral
5. coccygeal

Question 20

there are…pairs of…nerves in the brain

Answer 20

13
cranial nerves

Question 21

somatic nervous system aka…controls…

Answer 21

voluntary
movements and recieves sensory info

Question 22

dermatomes are…
myotomes are….

Answer 22

areas of skin supplied by one spinal nerve
muscle groups innervated by one spinal nerve

Question 23

autonomic system is..
it regulates…
its divided into…

Answer 23

largely unconcious
organ function/ glands/ smooth muscle
sympathetic and parasympathetic

Question 24

sympathetic is for…they are found in..
parasympathetic is for…they are found in…

Answer 24

fight or flight= increase heart rate/ and inhibit or relax most other organs that are not needed
middle region of spine (thoracic and lumbar)

rest and digest
top and end regions of spine (sacral and brain stem)

Question 25

glial cells/ neuroglia are… CNS and PNS both have...

Answer 25

non-neuronal cells in the central and peripheral nervous system different glia

Question 26

4 types of neuroglia in CNS

Answer 26

1. ependymal= line the ventricular system of brain and the central canal of spinal cord, ciliated= help cerebrospinal fluid to flow, can contribute to CSF production at choroid plexus (network of blood vessels) 2. astrocytes= form blood-brain barrier with capillaries (+metabolic and structural support) 3. oligodendrocytes= form myelin sheath (common in white matter) 4. microglia= immune cells of CNS+ general maintenance (clear up damaged cells and amyloid plaques)

Question 27

2 types of neuroglia in PNS

Answer 27

1. satellite cells= surround cell bodies in sensory/ sympathetic and parasympathetic ganglia= express ion channels and transporters for neurotransmitters+ regulate extracellular environment 2. Schwann cells= myein formation in PNS+ structural support (some are non-myelinating schwanncells= only provide support)

Question 28

myelination increases….as it allows...

Answer 28

conduction velocity saltatory conduction

Question 29

peripheral nerves can be clssified based on...

Answer 29

diameter and conduction velocity

Question 30

in the arlanger-gasser classification, groups A and B are…while C is.. group A has.. group C has...

Answer 30

myelinated unmyelinated largest diameter and fastest conduction speed (less friction)= somatic motor/ touch/ pressure/ pain B= pre ganglionic sympathetic smallest diameter and slowest speed (slow pain/ post ganglionic sympathetic)

Question 31

3 types of neurotransmitter:

Answer 31

1. excitatory= increases electrical excitability at post synaptic membrane 2. inhibitory= reduces electrical excitability 3. neuromodulator= alter the strength of transmission between neurones= affect amount of of transmitter produced and released

Question 32

5 classifications of neurotransmitter:

Answer 32

1. acetylcholine (key in activating muscle) 2. monoamines 3. amino acid neurotransmitters 4. peptide neurotransmitter (ie: endorphin and oxytocin) 5. miscellaneous neurotransmitter

Question 33

5 different types of monoamines

Answer 33

1. dopamine (pleasure and reward)= parkinsons/ schinzophrenia/ depression 2. noradrenaline (increase heart rate and blood pressure)= depressiona and anxiety 3. adrenaline 4. histamine 5. Serotonin (wellbeing and happiness= lack may lead to depression and anxiety)

Question 34

4 types of amino acid neurotransmitter role of GABA in body

Answer 34

1. Gamma-aminobutyric acid (GABA)= inhibitory 2. glycine= inhibitory 3. Glutamate= main excitatory 4. aspartate= excitatory -suppresses types of anxiety (lack leads to anxiety and epilepsy)

Question 35

2 types of post synaptic receptors

Answer 35

1. ionotropic receptors= ion channels that open and close when chamical messenger binds (ie ligand gated ion channels) 2. metabotropic= type of G-protein-coupled receptor (involve range of 2nd messenger signalling molecules)

Question 36

2 types of synapses

Answer 36

1. chemical synapses= release of neurotransmitter by exocytosis after action potential arrives 2. electrical synapses= direct physical connection between pre and post synaptic neurone= gap junction (allow current to flow)

Question 37

electrical synapses transmit signals...

Answer 37

faster than chemical synapses it can be bidirectional (depending on which neurone recieves the action potential first) enables synchronised activity of groups of cells

Question 38

structure of gap junction

Answer 38

1. made up of 2 half channels (hemichannels) 2. Join together to form entire channel (bridge the ectracellular space) 3. each half channel is called= connexon (made up of 6 symmetrical integral membrane proteins units called connexins)

Question 39

proprioceptors are...

Answer 39

a sensory receptor which receives stimuli from within the body, especially one that responds to position and movement.

Question 40

2 muscle proprioceptors

Answer 40

1. muscle spindles= located in muscle and activated when muscle is passively stretched= reflex arc to contract muscle= prevent overstretching ie knee-jerk reflex 2. golgi tendon organ= located in tendon and responds to excessive tension (when muscle contracts)= cause muscle to relax= prevent tendon tearing and muscle damage

Question 41

2 types of diseases that affect neural signalling

Answer 41

1. demyelinating diseases= damage of myelin sheath = slow nerve impulses - lead to deficiency in sensation, movement, cognition

Question 42

primary and secondary causes of demyelinating diseases

Answer 42

1. Primary= leukodystrophic diseases (abnoraml growth of white matter in brain)= myelin is abnormal and degenerates - genetic 2. secondary= myelinoclastic= healthy myelin destroyed by a toxic infectious agent/ chemical/ autoimmune

Question 43

2 examples of demyelinating diseases

Answer 43

1. multiple sclerosis (MS)= affects CNS, most common autoimmune= attach myelin sheath and oligodendrocytes= inflammatory response results in damage of axon and scarring 2. gullian-barre syndrome= affects PNS autoimmune= attack myelin and schwann cells, triggered by viral or bacterial infection

Question 44

Amyotropic lateral sclerosis is a diseae characterised by… evidence suggest its caused by...

Answer 44

progressive voluntary (striated) muscle weakness and paralysis affects somatic motor neurones excessive levels of neurotransmitter glutamate in synapse= overexcited motor neurones (glutamate toxicity) build up= due to loss of glutamate transporters (EAAT2)

Question 45

2 types of drugs that affect neurotransmitter uptake

Answer 45

1. Anti-depressants (selective serotonin reuptake inhibitors) SSRIS - prevent uptake of serotonin/ noradrenaline by pre neurone= more in synapse= more uptake by post neurone= promote happiness and wellbeing 2. cocaine= bind to dopamine transporters= more dopamine stays in synapse (similar to ecstasy= blocks uptake of serotinin and dopamine)