Ch 10: Nervous Tissue

Question 1

What are the 3 types of glial cells, what do they do and are they present in CNS, PNS or both?

Answer 1

They are in CNS only, they are microglia, asctrocytes and oligodendrocytes.
1. Microglia: if theres an inflammation they have the role of phagocytosis.
2. Astrocytes: form the blood brain barrier, gets rid of damaged nerves and doesn’t allow foreign particles to enter.
3. Oligodendrocytes: form the myelin sheath.

Question 2

Explain the difference between pseudounipolar, bipolar and multipolar neurons.

Answer 2

1. Pseudounipolar: have a single extension that divide into dendrite and axon (most sensory neurons are this)
2. Bipolar: have a dendrite and an axon.
3. Multipolar: numerous short extensions and a single long extension, axon (mostly CNS have this).

Question 3

What 3 structures are in the cell body of neurons?

Answer 3

1. Nucleus
2. Cell organelles, mito, Golgi,lysosomes
   3.organelle specific to neuron: Nissl body

Question 4

What is the length and diameter of the axon?

Answer 4

Can reach up to 1 m length and microscopic diameter.

Question 5

What are Schwaan cells?

Answer 5

Cells in PNS that synthesise myelin sheath.

Question 6

What can damage of myelin sheath in CNS lead to?

Answer 6

Multiple sclerosis.

Question 7

What are the epinerve and perinerve?

Answer 7

Epinerve is the tissue on the outside of the nerve, perinerve is sheath around each nerve bundle.

Question 8

What is the resting potential in a neuron?

Answer 8

-70 mV.

Question 9

What results in a resting potential?

Answer 9

Excess positively charged ions outside cell mb, slight excess negative charge inside cytoplasm.
Concentration outside cell is more than 10 times higher than inside.

Question 10

How many Na and K are transported in and out, which is in which is out?

Answer 10

3Na out, 2K in.

Question 11

How many Na and K are transported in and out, which is in which is out?

Answer 11

3Na out, 2K in.

Question 12

What value does the resting potential have?

Answer 12

+35 mV.

Question 13

What value does the threshold potential have?

Answer 13

-55 mV.

Question 14

What value does the threshold potential have?

Answer 14

-55 mV.

Question 15

Explain the process of neuron repolarization and repolarization.

Answer 15

1. Resting potential: -70mV, 3 Na out 2K in to maintain rp. Outside cell more positive than inside.
2. Dep: stimulus, Na in cell making it more positive.
3. Threshold: -55 mV, so if this is reached = action potential.
4. Rising: more Na channels open, inside becomes even more positive.
5. Peak: na channels close k channels open
6. Rep: k out of neuron inside becomes negative.
7. Hyperpolarisation: briefly value goes below resting potential, to prevent another stimulus from being done at the same time.
8. Resting p: Na/K pump restored.

Question 16

Where are the locations and what are the functions of the following neurotransmitters: Ach, glicine, noradreline, dopamine, serotonin, acid gama aminobutiric?

Answer 16

1. Ach: location in neuromuscular junction, SNV and brain, function, excited muscle, slows heartbeat, transmits signals in SNV.
2. Glicine: location, spinal cord, function: inhibits various neurons.
3. Noradrenaline: location, brain, SNS, function: regulates viscera and some brain functions.
4. Dopamine: brain, controls some motor functions.
5. Serotonin: brain, spinal, functions: circadian rythm regulation, sleep and wakefulness regulation, mental functions.
6. Acid Gama aminobutiric: location, brain, spinal cord, function, inhibits various neurons