4- Nerve

Question 1

Describe the cerebral hemispheres

Answer 1

Lobes:
Parietal (top) -sensory and motor function
Occipital (back) -visual
Frontal
Temporal (middle) -sound and speech recognition
Gyri are ridges
Sulci are valleys

Question 2

What makes up the brain stem?

Answer 2

Midbrain
Pons
Medulla

Question 3

Describe types of neurone

Answer 3

Unipolar e.g. in retina (single axon)
Pseudounipolar (single axon splits in 2)
Bipolar (axon and dendrite) found mainly in PNS
Multipolar (Golgi -gaba neurone in cerebellum, purkinje -gaba neurone in cerebellum, pyramidal)

Question 4

Describe structure of a neurone

Answer 4

Soma: neurofilaments provide structural support and transport
Axon: originates from axon hillock, branches into collaterals, myelinated
Dendrites: non-myelinated, receive info

Question 5

What are astrocytes?

Answer 5

Most abundant cell in CNS, provide structural support to neurones, can proliferate
Can repair by providing nutrients to neurones
Act as facultative macrophages
Carry out homeostasis (mop up neurotransmitter and other substances)

Question 6

What are oligodendrocytes?

Answer 6

Produce myelin for many axons in the CNS

Question 7

What are Schwann cells

Answer 7

Each produce myelin for 1 axon in PNS

Question 8

What are microglia?

Answer 8

Macrophages

Question 9

What are ependymal cells?

Answer 9

Epithelial cells that line the ventricles, regulate CSF production

Question 10

What are neuroglia?

Answer 10

All cell types in CNS apart from neurones

Question 11

Describe the RMP

Answer 11

4 major physiological ions - potassium (K+), sodium (Na+), chloride (Cl-) and calcium (Ca2+)
•Cell membranes - impermeable to these ions  transportation regulated by channels & pumps
•This causes an uneven ion distribution:
•High extracellular - Na+ & Cl-
•Low extracellular - K+
•High concentration gradient for Ca2+
•Difference in concentration  creates a potential difference across the membrane
•Neuronal cells -
•Negative charge inside compared to outside
•RMP of between -40 to -90mV

Question 12

What are the ion concentrations at RMP?

Answer 12

Extracellular: K+(4mM), Na+ (140mM),, Cl-(120mM), Ca2+(2mM)
Intracellular: K+(150mM), Na+(10mM), Cl-(5mM), Ca2+ (0.0001mM)