Cells and tissues of the nervous system Flashcards

1
Q

What makes up the CNS

A

Brain and spinal cord - control centres for whole nervous system

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2
Q

what makes up PNS

A

Cranial and spinal nerves

conduits - carry impulses from CNS to peripheral organs and structures

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3
Q

Division of PNS?

A

sensory afferent (to CNS) or afferent (motor) division (CNS to PNS)

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4
Q

Somatic motor function

A

skeletal muscle - voluntary movements

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5
Q

Autonomic division

A

sympathetic or parasympathetic (involuntary movements)

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6
Q

The entire nervous system is made up of which 2 types of cells?

A

neurons

glial cells

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7
Q

What is a neuron

A

excitable cells that carry impulses in form of AP’s

structural and functional unit of the nervous system

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8
Q

What are glial cells?

A

Supportive cells - non-excitable

much smaller than neurons and more of them

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9
Q

Describe a typical neuron

A
  • Has multiple dendrites and one axon
  • Nucleus- loose chromatin, prominent nucleolus.
  • High metabolic rate
  • Long living and amitotic - don’t regenerate
  • Cytoplasm in the cell body is perikaryon and in the axon is axoplasm

An impulse transmission is by AP which can travel in only one direction from cell body to synaptic terminal

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10
Q

What does a myelin sheath do?

A

Increases conduction speed of AP in axons by ‘saltatory conduction’ (jumping from node of Ranvier to node of Renvier)

Myelin sheath is just the cell membrane of the axon - fatty - appears white (white matter)

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11
Q

What forms a myelin sheath in the PNS?

A

schwann cells (type of glial cell)

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12
Q

What forms a myelin sheath in the CNS?

A

oligodendrocytes (type of glial cell)

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13
Q

Types of neurons?

A

Multipolar - typical neuron, branches of lots of dendrites
Bipolar
Pseudounipolar neuron

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14
Q

What is a Pseudounipolar neuron like?

A

All its dendrites are joined up as one

smaller cell body - located in ganglia

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15
Q

All sensory neurons are of what type? where do their cell bodies lie?

A

pseudounipolar

cell bodies lie in ganglia (dorsal root ganglia)

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16
Q

All motor neurons are of what type? where do their cell bodies lie?

A

multipolar

ventral root (motor) so cell bodies lie in grey matter of spinal cord

17
Q

Why do neurons have lots of mitochondria and endoplasmic reticulum?

A

cell body is making neurotransmitter that then travels down the axon to be stored in the vesicles and then secreted when an AP or impulse reaches there

18
Q

Multiple Sclerosis

A

own immune system attacks myelin sheath - patchy loss

nerve conduction across affected axons abnormal

Cause unknown (? Viral, ?autoimmune)

MRI shows whitish plaques of demyelination

Scotland has HIGHEST incidence in the world

19
Q

What is white matter?

A

myelinated axons- bundled together depending on what modality they are carrying - sensory or motor

either running to cerebral hemisphere or down from it

20
Q

What is grey matter?

A

neuronal cell bodies

21
Q

What is a tract

A

bundles of fibres (mainly myelinated axons) that are sitting in the white matter of the spinal cord

22
Q

Collection of cell bodies within the CNS is called what?

A

a nucleus

23
Q

How many types of glial cells are there? Name them

A

6 different types

within CNS - 4 types:
astrocytes 
oligodendrocytes
microglia 
ependymal cells

Within PNS - 2 types:
Schwann cells
Satellite cells

24
Q

What are tumors of glial cells called?

A

glioma

25
Q

Why are astrocytes important?

A

they cover capillaries and synapses so keep neurotransmitter localised in these synapses

help form blood brain barrier

26
Q

Importance of microglia

A

responsible for phagocytosis and scar tissue formation in CNS

27
Q

Importance of ependymal cells

A

line ventricles in the brain

28
Q

Importance of satellite cell

A

surround neuronal cell bodies - help to nourish and support them

29
Q

What is the blood brain barrier

A

Is a protective mechanism that helps maintain a stable environment for the brain and prevents harmful amino acids & ions present in the bloodstream and blood cells from entering the brain.

30
Q

Special features of the BBB

A

Endothelium has tight junctions

thick basal lamina

foot processes of astrocytes - prevents stuff from leaking out of the capillaries

31
Q

Drug delivery into the CNS

A

drugs have to be lipid soluble or use suitable vectors

32
Q

How many ventricles are there in the brain

A

4
lateral ventricle x2
III ventricle
IV ventricle

33
Q

What does the subarachnoid space contain?

A

cerebrospinal fluid

34
Q

Where is CSF present?

A

inside ventricles

between pia and arachnoid layers

35
Q

What forms CSF?

A

Choroid plexus in each ventricle

36
Q

Where is CSF absorbed?

A

by arachnoid villi into saggital sinus (around outside of skull)