Ch. 3 Central Nervous System

Question 1

The Brain (Forebrain/Cerebrum/Brain Stem)

Answer 1

forebrain: cerebrum- cerebral cortex and basal nuclei; diencephalon- thalamus and hypothalamus
cerebellum: spinoellum, cereboellum, vestibuloellum
brain stem: midbrain, pons, medulla oblongata

Question 2

Afferent Neurons

Answer 2

head to the CNS; receptor, peripheral axon, cell body, central axon, CNS

Question 3

Interneurons

Answer 3

classic neurons (99%), create complexity (behaviour, emotion, motivation)

Question 4

Efferent Neurons

Answer 4

head away from the CNS; cell body, axon, axon terminal, effector

Question 5

Glial Cells or Neuroglia

Answer 5

provide physical, metabolic, and functional support

- dividing cells form gliomas (brain tumour)

Question 6

Glial Cells in PNS

Answer 6

Satellite Cells: form capsules around cell bodies; called ganglia
Schwann cells: myelin; neurotropic factors

Question 7

Glial Cells in CNS

Answer 7

Oligodendrocytes: form myelin sheath
Astrocyte: secrete paracrine signals that form tight junctions which make up the BB; form neurotrophic factors
Microglia: stationary until commanded, immune cells (scavengers), misbehaviour= Alzheimer’s, Dementia, brain degeneration (AIDS)
Ependymal cells: line cavities of brain (ventricles), secretion of cerebrospinalfluid, stem cells for new neurons, disease= Alzheimer’s (hippocampus)

Question 8

Basal Nuclei

Answer 8

• inhibition of muscle tone
• coordination of slow, sustained movements
• suppression of useless patterns of movement

Question 9

Meningeal Membrane

Answer 9

dura mater: tough, elastic covering consisting of two layers; dural or venous sinuses; venous blood drains from the brain empties into these sinuses to be returned to the heart
arachnoid mater: “cobweb” appearance; filled with CSF, arachnoid villi pentrate gaps and project into dural sinuses; CNS is reabsorbed across the surfaces of these villi into blood circulating within sinuses
pia mater: most fragile, highly vascular; bring a rich blood supply into close contact with ependymal cells lining ventricles

Question 10

Somatosensory Cortex

Answer 10

• posterior to central sulcus
• receives somaesthetic and proprioceptive input; face, tongue, hands, genitalia are high
• localizes the source of sensory input and perceives the level of intensity

Question 11

Premotor Cortex

Answer 11

coordination of complex movements

Question 12

Supplementary Motor Area

Answer 12

on inner surface- not visible; programming of complex movements

Question 13

Posterior Parietal Cortex

Answer 13

integration of somatosensory and visual input; important for complex movements

Question 14

Embryonic Development

Answer 14

day 20 (3wks): neural plate starts to fold in; crest cells develop (PNS)
day 23: CNS; lumen
day 28 (4wks): forebrain midbrain and hindbrain develop
day 48 (6wks): cerebrum and diencephalon (forebrain), medulla oblongata, pons, cerebellum (hindbrain), midbrain stays same
11 wks: cerebrum grows more rapid; all grow