2.2: Cells of the nervous system & neuromuscular junction Flashcards

1
Q

What is the telencephalon also known as?

A

Cerebral hemisphere

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2
Q

What are the ridges on the telencephalon called?

A

Gyri

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3
Q

What are the valleys on the telencephalon called?

A

Sulci

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4
Q

4 lobes of the cerebral hemisphere

A

Frontal
Parietal
Temporal
Occipital

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5
Q

Function of the frontal lobe of the cerebral hemisphere

A

Responsible for executive functions such as personality

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6
Q

Function of the parietal lobe of the cerebral hemisphere

A

Contains the somatic sensory cortex responsible for processing tactile information

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7
Q

Function of the temporal lobe of the cerebral hemisphere

A

Contains important structures (hippocampus - short term memory, amygdala -behaviour, Wernickes area- auditory perception and speech)

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8
Q

Function of occipital lobe of cerebral hemisphere

A

Processing of visual information

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9
Q

3 main structures of brain stem in descending order

A

Midbrain
Pons
Medulla

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10
Q

Location and function of brain stem

A

Dorsal region of CNS
role in motor coordination, balance and posture

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11
Q

4 morphologies of neurons

A

Unipolar
Pseudo-unipolar
Bipolar
Multipolar ( pyramidal, purkinje, Golgi cells)

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12
Q

Define soma

A

Cell body

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13
Q

Most abundant cell type in CNS

A

Astrocyte

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14
Q

Morphology of unipolar neurons

A

1 axonal projection

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15
Q

Morphology of pseudo-unipolar neurons

A

Single axonal projection that divides into two

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16
Q

Morphology of bipolar neurons

A

2 projections from cell body

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17
Q

Morphology of multipolar neurons

A

Numerous projections from cell body

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18
Q

Morphology of pyramidal cells

A

‘Pyramidal’ shaped cell body

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19
Q

Where are purkinje cells and Golgi cells found

A

They are GABA neurons found in cerebellum

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20
Q

What are the functions of Oligodendrocytes and Schwann cells

A

Myelin producing cells

21
Q

What is the difference between Oligodendrocytes and Schwann cells

A

O - work in CNS
S - work in PNS

O- capable of myelinating a number of axons
S- only myelinated a single axon segment

22
Q

microglial cell

A

Performs immune functions in CNS
act as macrophages in CNS

23
Q

Ependymal cells

A

Epithelial cells (that line fluid-filled ventricles) regulating production and movement of CSF

24
Q

Resting membrane potential of neurones

A

Around -70mV

25
Q

If membrane potential is too negative, cell is said to be

A

Hyperpolarised

26
Q

If membrane potential becomes more positive what is the cell said to be

A

Depolarised

27
Q

4 ions controlling resting membrane potential

A

K+
Na+
Cl-
Ca2+

28
Q

What are the relative concentrations of RMP ions extracellularly compared to intracellularly

A

Higher Na+
Higher Cl-
Lower K+
Higher Ca2+ (High concentration. Gradient)

29
Q

Explain how ions are involved in generating an action potential

A

Influx of Na+ via voltage gated sodium ion channels (VGSC) leads to further depolarisation

30
Q

Explain how the ions are involved in the restoration of RMP

A

Voltage gated potassium ion channels open at slower rate, leading to effluent of K+ from cell which repolarises the membrane

31
Q

How is the Na+/K+ ATPase involved in restoring the ion gradients

A

At rest - Na+ enters, phosphorylated, ions are transported through the protein against conc. gradient
Active configuration - Na+ removed from cell and K+ enters against conc. gradient. The pump returns to rest and K+ transported back into cell

32
Q

Process by which AP spreads along axon

A

Cable transmission

33
Q

What is saltatory conduction

A

AP “jumps” between nodes to get to pre-synaptic terminal faster

34
Q

Function of myelin in speed of conduction

A

Prevents action potential spreading
It has a high resistance and low capacitance

35
Q

What are the nodes of ranvier

A

Gaps of no myelin intermittently along the axon

36
Q

What happens when the action potential reaches the synapse?

A

AP opens V gated Ca2+ channels at pre-synaptic terminal
Ca2+ influx, down conc. gradient causing exocytosis of vesicles containing neurotransmitter
Neurotransmitter released into synaptic cleft
Binds to receptors on post-synaptic membrane
Enzymes break down neurotransmitter to be uptaken again by pre-synaptic cleft / recycled by transporter proteins

37
Q

How does an action potential travel across a neuromuscular junction.

A

Action potential propagated along axon (Na+ and K+) → Ca2+ entry at presynaptic terminal

Ca2+ entry → ACh release into synapse

ACh binds to nicotinic ACh receptors (nAChR) on skeletal muscle → change in end-plate potential (EPP)

Miniature EPP: Quantal ACh release

AP travels through T-tubules that are continuous with sarcolemma & closely connected to sarcoplasmic reticulum

38
Q

Where is the sarcoplasmic reticulum in relation to myofibrils

A

Surrounding myofibrils (contractile units of muscle)

39
Q

What is the function of the sarcoplasmic reticulum and what effect does it have?

A

Ca2+ storage —> Ca2+ release following sarcolemma depolarisation

Ca2+ —> myofibrils and muscle contraction

40
Q

What is myasthenia gravis and what does it cause

A

Autoimmune disorder - antibodies directed against ACH receptor
Causes fatigable weakness

41
Q

Astrocytes

A

structural cells
play important role in cell repair, synapse formation, neuronal maturation and plasticity

42
Q

Graded potential

A

Membrane potential change that is not an action potential
- produce initial change in membrane potential, can initiate or prevent action potentials

43
Q

Neuromuscular junction

A

Specialised structure incorporating axon terminal and muscle membrane, allowing unidirectional communication between peripheral nerve & muscle

44
Q

Communication across neuromuscular junction

A

Paracrine : neurotransmitter released

45
Q

Sacrolemma

A

skeletal muscle membrane : nAChR activation -> depolarisation -> AP

t tubules : continuous with sarcolemma, closely connected to sarcoplasmic reticulum

AP travels through T tubules

46
Q

3 neuromuscular junction disorders

A

Botulism
Myasthenia Gravis (MG)
Lambert-Eaton myastenic syndrome (LEMS)

47
Q

Botulism

A

BTx : irreversible
disrupts stimulation-induced Ach release from pre-synaptic nerve terminal

48
Q

Lambert-Eaton myastenic syndrome (LEMS)

A

Autoimmune disorder - antibodies directed against VGCC