Module 4 sem 1 exam (action potential, neuroglial cells, and areas of brian)

Question 1

What is action potential

Answer 1

change in membrane polarity produced by voltage-gated ion channels
-only occurs where have high density of voltage-regulated gates

Question 2

Describe the process of action potential across axon

Answer 2

1. Arrival of current at axon hillock depolarises membrane
2. Local pot. reach -55 mV threshold
3. voltage-gated Na^+ channels open, Na^+ enters & depolarises cell, opening more channels=rapid pos. feedback cycle
4. once membrane potential rises above 0 mV, Na^+ channels inactivated & close
5. voltage peaks at +35 mV, membrane now [+ve] inside & [-ve] outside
6. Slow K^+ channels open & outflow of K^+ repolarises
7. K^+ channels remain open so membrane briefly hyperpolarised (more neg than RMP)
8. RMP restored as Na^+ leaks in & K^+ removed by astrocytes

Question 3

Describe some functions of neuroglia (support cells)

Answer 3

-protect neurons & help them function
-bind neurons together & form framework for nervous tissue
-prevent neurons from touching each other

Question 4

Name the four types of CNS neuroglia

Answer 4

oligodendrocytes
ependymal cells
microglia
astrocytes

Question 5

Describe the function of oligodendrocytes (Look at diagram)

Answer 5

form myelin sheaths in CNS- speed signal conduction

Question 6

Describe the function of ependymal cells (Look at diagram)

Answer 6

secrete & circulate cerebrospinal fluid (CSF)

Question 7

Describe the function of microglia (Look at diagram)

Answer 7

func: wander through CNS looking for debris & damage

Question 8

Describe the function of astrocytes (Look at diagram)

Answer 8

func: secrete nerve growth factors
-convert glucose to lactate & supply this to neurons

Question 9

Name the types of PNS neuroglia

Answer 9

schwann and satellite cells

Question 10

Describe the function of schwann cells (Look at diagram)

Answer 10

assist in regeneration of damaged fibers and produce myelin sheath

Question 11

Describe the function of satellite cells (Look at diagram)

Answer 11

provide electrical insulation around neurosoma
-regulate the chemical environment of neurons

Question 12

Look at diagram of brain

Answer 12

….

Question 13

Describe broca’s area (and location)

Answer 13

-inferior prefrontal cortex usually in left hemisphere
-generates motor program for muscles of larynx, tongue, cheeks & lips for speaking & for hands when signing
-transmits program to primary motor cortex for commands to lower motor neurons that supply relevant muscles

Question 14

Describe wernickes areas (and location)

Answer 14

-posterior to lateral sulcus usually in left hemisphere
-permits recognition of spoken & written language
-formulates phrases & transmits plan of speech to Broca’s area