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Flashcards in Session 9 Deck (28):
0

What types of nerve cells are there?

- Glia (90%)
- Neurones (10%)

1

What can neuroglia be divided into?

- Microglia
- Macroglia

2

Describe the types of Macroglia

- Astrocytes: comprise the blood brain barrier, assist in transfer of nutrients and waste, phagocytic functions, physical support for neurones, found in CNS
- Oligodendrocytes: myelinated up to 250 axons per cell in CNS
- Ependyma: Line ventricles and central canal of spinal chord, found in CNS
- Swann cell: myelinated 1 axon per cell in PNS
- Satellite cells: physical support of neurones in PNS

3

What is the function of glial cells?

- Support neurones
- Maintain homeostasis
- Form myelin and insulate neurones

4

What is the function of Microglia?

- Immune and inflammatory functions
- Found in both CNS and PNS

5

What do neurone cell bodies contain?

- Nissl substance (protein synthesis)
- Nucleus and nucleolus
- Golgi apparatus (packaging transmitters into vesicles)
- Dendrites

6

Where is the nucleus in healthy neurones?

- Central

7

What is grey matter?

- Collections of neuronal cell bodies
- Nuclei in CNS
- Ganglia in PNS

8

What is white matter?

- Collections of axons eg a peripheral nerve
- Fibre tracts in CNS
- Nerves in PNS

10

How are peripheral nerves arranged?

- Singular axon is covered by endoneurium
- Group of axons in a fascicle is covered by a perineurium
- Group of fascicles and blood vessels in a peripheral nerve is surrounded by an epineurium

11

What happens if a neurone is severed?

- Nerve stump is formed (proximal segment of axon seals to prevent leakage of cell contents)
- Distal segment dies and undergoes Wallerian degeneration as is cut off from nutritional support of cell body
- Cell body puffs up with increased contents
- Nucleus displaced to the periphery
- Process is chromatolysis

12

What is an afferent neurone?

- Carries signals from periphery to CNS
- Sensory neurone

13

What is an efferent neurone?

- Neurone that carries signals from the CNS to the periphery
- Motor or autonomic neurone

14

How do Schwann cells insulate neurones?

- Doesn't conduct electricity due to lipid content

15

How can efferent nervous system (signals from CNS) be divided?

- Somatic
- Autonomic:
~ Sympathetic
~ Parasympathetic

16

Describe the structure of the somatic NS

- 1 neurone carries signal directly to effector organ
- Effector organ: always skeletal muscle
- Efferents are under-developed at birth but fully developed by puberty

17

What are the functions of the autonomic nervous system?

- Homeostasis of the internal environments through regulation of systems in the body eg cardiovascular, respiratory, digestive, thermoregulative
- Promotes excretory mechanisms of the body as and when necessary

18

What are the effector organs of the autonomic nervous system?

- Visceral organs
- Smooth muscle
- Secretory glands
- Cardiac muscle

19

Compare the sympathetic and parasympathetic systems within the autonomic nervous system

- Common standard anatomical layout eg same number of synapses
- Differ in detail of respective anatomy eg lengths of neurones
- Equal number of synapses in a series arrangement
- Various synapses use different neurotransmitters

20

What is the general layout of the autonomic nervous system?

- 2 neurones meet at a ganglion in the PNS
- One cell body in the CNS (pre-ganglionic neurone)
- One cell body in the PNS (post-ganglionic neurone)
- Post-ganglionic neurone ends at the effector organ
- Meninges is the barrier between CNS and PNS

21

What is the outflow for the sympathetic nervous system?

- Thoraco-lumbar outflow

22

What is the outflow for the parasympathetic nervous system?

- Cranial-sacral outflow

23

Describe the structure of the sympathetic nervous system

- Nerve fibres have cell bodies in all 12 thoracic sections and the first 2 lumbar sections
- Have short pre-ganglionic neurones and long post-ganglionic neurones

24

Describe the structure of the parasympathetic nervous system

- Long pre-ganglionic neurones and short post-ganglionic neurones

25

What are the functions of the sympathetic nervous system?

- Fight/Flight/Fright response
- Diversion of blood to muscles and heart
- Increase in heart rate
- Increase in blood pressure
- Reduced blood flow to GI tract and skin
- Hyperventilation

26

What are the functions of the parasympathetic nervous system?

- Relaxation
- Reduced heart rate and force of contraction
- Promotes digestion
- Promotes bodily functions such as bladder emptying
- Promotes sleep

27

What neurotransmitters are used in the sympathetic nervous system?

- Pre-ganglionic neurones are cholinergic (use acetylcholine)
- Post-ganglionic neurones express nicotinic receptors, are noradrenergic (use noradrenaline)
- Exception: perspiration and ejaculation pathways have cholinergic

28

What neurotransmitters are used in the autonomic nervous system?

- Pre-ganglionic neurones are cholinergic (use acetylcholine)
- Post-ganglionic neurones express nicotinic receptors and are cholinergic (use acetylcholine)