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Y1 IMS > Nerves > Flashcards

Nerves Flashcards

1
Q

How are the nerves organised

A

The Central Nervous system and The peripheral nervous system

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2
Q

What is the CNS

A

Central nervous system which includes the brain and spinal cord
It receives, processes, interprets and stores information and sends messages destined for muscles, glands and organs

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3
Q

What is the PNS

A

The peripheral nervous system

Which transmits information to and from the CNS by way of sensory and motor nerves

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4
Q

What are the two divisions of the PNS

A

Somatic nervous system

Autonomic nervous system

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5
Q

How can the autonomic nervous system be further divided

A

Sympathetic: fight to flight
Parasympathetic: rest and digest
Enteric and cardiac plexus

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6
Q

What is the role of the autonomic nervous system

A

Regulates involuntary processes, including heart rate, respiration, digestion and pupil contraction

Operates automatically without conscious direction

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7
Q

What is the role of the somatic nervous system

A

Carries sensory information form the sensory organs to the CNS and relays motor commands to the muscle

Controls voluntary movements

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8
Q

What are the characteristics of neurones

A

Cells specialised for fast communication
High metabolic rates
Main component of brain’s grey matter
Can be classified by size, shape, connections, function, transmitters

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9
Q

What are the dendrites, axon, and synaptic terminals

A

Dendrites: signal inputs
Axon: signal conduction
Synaptic terminals: signal output

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10
Q

What are the three sizes of neurones

A

Multipolar neurone
Unipolar neurone
Bipolar neurone

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11
Q

What is contained within white matter

A

Axons carrying information to and from the brain

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12
Q

What are ganglia

A

Nodular masses of neurone cell bodies (ganglion cells) and supporting neuroglia (satellite cells)

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13
Q

What are the two types of ganglia in the PNS

A

Sensory: cell bodies of sensory neurones
Autonomic: cell bodies of efferent neurones from the autonomic nervous system

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14
Q

What are neuroglia

A 
Supporting cells for neurones
Regulate neurone metabolism and function
Repair and recovery from injury
Regulate blood brain barrier
Destroy pathogens and remove dead neurones
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15
Q

What are the main types of neuroglia in the CNS

A

Astrocytes
Oligodendrocytes
Microglia
Ependyma

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16
Q

What are the main types of glial cells in the PNS

A

Satellite cells

Schwann cells

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17
Q

What is myelination

A

The process by which the fact membrane is generated around the axon

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18
Q

What is the spinal cord reflex pathway

A

Sensory receptor (site of stimulus) -> Sensory neurone (transmits afferent information to the CNS) -> Integration centre (one or more synapses within the CNS) -> Motor neurone (conducts efferent impulses to the effector organ) -> Effector (muscle fibre or gland response to impulses)

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19
Q

What is the average resting membrane potential

A

-65mV

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20
Q

What factors contribute to the resting membrane potential

A

Charged intracellular proteins
Na+/K+ pump
Potassium ions
Sodium ions

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21
Q

What is an action potential

A

The means by which a neurone sends information down its axon away from the cell body
It is an explosion of electrical activity that is created by a depolarising current

22
Q

What is sensory transduction

A

Conversion of environmental or internal signals into electrochemical energy

23
Q

What are the two types of synapses

A

Electrical: direct passage of current via ions flowing through gap junctions
Chemical: release of vesicles containing chemical transmitter which has an effect on receptors on a target cell

24
Q

What is a neurotransmitter

A

A substance that is release at a synapse by one neurone that affects another cell, either neurone or effector organ in a specific manner

25
Q

What is a neuromodulator

A

A substance that is release and modifies the action of a neurotransmitter but does not have a direct action itself

26
Q

What is a neuroactive substance

A

A neutral tem is a substance is known to have an effect in the CNS but its precise action is not known

27
Q

What is an inotropic receptor

A

A cluster of similar subunits forming ion channels that depolarise or hyper polarise the postsynaptic cell

28
Q

What is a metabotropic receptor

A

A 7-transmembrane molecule coupled to intracellular proteins that transduce a signal to cell interior

29
Q

What are the components of the motor unit

A

Motor unit consists of the motor nerve and all the muscle fibres innervated by that nerve with a size that depends on the function of the muscles

30
Q

Where are the neurotransmitter vesicles

A

Neurotransmitter vesicles are lined up directly above structures on the postsynaptic cell known as postjunctional folds, which is where the neurotransmitter receptors are concentrated

31
Q

What are the steps of neuromuscular transmission

A

Arrival of action potential depolarisation of terminal bouton -> Opening of voltage gated calcium channels -> Influx of calcium into the synaptic bouton -> Fusion of vesicles -> Exocytosis (release of ACh)-> Binding of ACh to nicotinic receptors on muscle cell membrane receptor activation -> Na+ enters -> membrane depolarisation

32
Q

What drugs are used at the NMJ

A

Non depolarising competitive nAChR antagonist
Depolarising nAChR agonist
Cholinesterase inhibitors

33
Q

What are some NMJ disorders

A

Lambert-eaton syndrome

34
Q

Explain the functional anatomy of the neuromuscular junction

A

Highly specialised point of contact between the motor nerve cell carrying information from the CNS to the muscle fibre cells

35
Q

What are non-depolarising competitive nAChR agonists

A

Mechanism: competes with ACh for nicotinic receptor binding sites causing gradual muscle paralysis

Reversed by AChR inhibitors

Hydrolysed by circulating esterase

Therapeutic use: surgery

Adverse effect: decrease BP, bronchospasm

Example: Tubocurarine

36
Q

What are depolarising nAChR agonists

A

Mechanism: persistent depolarisation of the neuromuscular junction

Phase I: membrane depolarised causing brief period of muscle fasciculation (twitching)

Phase II: End plate eventually depolarises, but due to slow metabolism compared to ACh it continues to occupy the receptor (Flaccid paralysis)

Hydrolyse by circulating esterase

Therapeutic use: surgery given continuous IV short acting

Adverse effects: when administrated with halothane genetically susceptible people experience hyperthermia

Example: Succinylcholine

37
Q

What are cholinesterase inhibitors

A

Mechanism: Inhibits AChR

Therapeutic use: antidote for non depolarising blockers. Treatment and diagnosis for myasthenia gravis. Nerve gas

Adverse effects: generalised cholinergic activation, abdominal cramping, diarrhoea, salivation, incontinence

Example: neostigmine

38
Q

What are the three types of muscles

A

Skeletal
Smooth
Cardiac

39
Q

What are the characteristics of cardiac muscle structure

A

Specialised form of skeletal muscle
Striated
Branched
Interconnected
Cardiac cells smaller the skeletal muscle cells
Rich in glycogen, myoglobin, and mitochondria
Contains actin and myosin myofilaments

40
Q

What is the ultrastructure of cardiac muscle

A

Each cell usually contains 1-2 centrally located nuclei

Mitochondria comprises 30% of volume of cell vs only 2% in skeletal cell

41
Q

What cell junctions make up an intercalated disc

A

Fascia adherens: anchoring sites for actin, connect to the closest sarcomere
Desmosomes (macula adherens): stop separation during contraction by binding intermediate filaments, joining the cells together.
Gap junctions: allow action potentials to spread between cardiac cells by permitting the passage of ions between cells, producing depolarisation of the heart muscle

42
Q

What are the 4 main classes of antiarrhythmics

A

Class I: sodium channel blockers; treat ventricular ectopics
Class II: beta blockers; slow conduction in the SA and AV nodes
Class III: potassium channel blockers; treat ventricular tachycardia and atrial fibrillation
Class IV: calcium channel blockers; slow conduction in the SA and AV nodes

43
Q

What are the upstrokes dependent on

A

SA and AV node action potential upstroke is Ca2+ dependent

Ventricular upstroke is Na+ dependent

44
Q

What are the structural characteristics of smooth muscle

A

Usually 2 sheets of closely opposed fibres
Walls of all blood vessels except the smallest blood vessels and in the walls of hollow organs
Alternating contraction relaxation of 2 layers mixes substances in lumen of hollow organs causing peristalsis

45
Q

What is the ultrastructure of smooth muscle

A

Fibres smaller than those in skeletal muscle
Spindle-shaped
Single central nucleus
More actin than myosin
No sarcomeres
Not well organised
No T-tubules and the sarcoplasmic reticulum is poorly developed

46
Q

What are single-unit vs multi-unit smooth muscles

A

Single-unit: unitary smooth muscle, most common, gap junctions so act as a single-unit

Multi-unit: Lack gap junctions, cells innervated individually

47
Q

What are the characteristics of pennate muscles

A

Feather-like in the arrangement of fascicles (fibre bundles)

Unipennate, bipennate, multipennate

48
Q

What is the characteristic of fusiform muscles

A

Spindle-shaped

49
Q

What is the characteristic of parallel muscles

A

The fascicles lie parallel to the long axis of the muscle

Flat muscles with parallel fibres often have aponeuroses

50
Q

What is the characteristic of convergent muscles

A

Have a broad attachment from which the fascicles converge to a single tendon

51
Q

What is the characteristic of circular muscles

A

Surround a body opening or orifice, constricting it when contracted

Y1 IMS (9 decks)

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