Lecture 3: Units of the Nervous System

Question 1

Describe function of soma/cell body

Answer 1

Process information, house cel, nucleus

Question 2

Describe dendrites

Answer 2

Branching extensions from soma
Receive information from other nerves
# of dendrites = amount of incoming info

Question 3

Describe dendritic spines

Answer 3

Protrusions from dendrites that are point of contact on axons

Question 4

Describe axon

Answer 4

Long protrusion exiting soma which is covered in myelin, carrying nerve signal away

Question 5

Describe myelin sheath

Answer 5

Made from glial cells, coating the axon in order to speed communication, nodes of Ranvier are not covered

Question 6

Describe axon hillock

Answer 6

Point where axon leaves cell body

Question 7

Describe axon collaterals

Answer 7

Point where axon branches out, allows messages to go to multiple terminals

Question 8

Describe terminal button

Answer 8

End of axon collateral that stops close to dendritic spine of communicating neuron, but does not touch

Question 9

Describe synapse

Answer 9

Junction between axon collateral of one neuron, and dendritic spine of next. It is a small space between terminal button and dendritic spine

Question 10

List the three types of neurons

Answer 10

1. Sensory - info to the brain
2. Inter neurons - connect sensory and motor
3. Motor - info from brain to muscles

Question 11

What are two kinds of sensory neurons

Answer 11

Bipolar (in retina)

Somatosensory - skin, muscle

Question 12

List three kinds of interneurons

Answer 12

Stellate - in thalamus, small and starlike
Pyramidal - in cortex, long axon and two sets of dendrites
Purkinje - in cerebellum, long axon, dendrites like tree

Question 13

Describe a motor neuron

Answer 13

Extensive dendrites to collect lots of info from multiple sites, large cell body to process info, super long axon

Question 14

List five types of glial cells and their functions

Answer 14

Ependymal - on walls of ventricles, produce CSF
Astrocyte - structural support, regulate BBB
Microglia - immune functions, engulf foreign bodies
Oligodendroglia - insulate axons in CNS
Schwann - insulate axons in PNS

Question 15

How are damaged neurons repaired in the PNS?

Answer 15

When axon is cut, it dies. Microglia remove debris. Schwann cells shrink and divide making new cells along axons former path. Neuron sends out axon sprouts which find Schwann cells along path and create a new axon. Schwann cells envelope new axon, creating myelin

Question 16

Describe cell membrane

Answer 16

Separates intracellular fluid from extra cellular via the phospholipid bilayer. The head of the bilayer is hydrophilic, while the tails are hydrophobic. It regulates movement of substances in and out of cell

Question 17

Describe the nucleus

Answer 17

Contains genes which are inside chromosomes. Gene is to page as chromosome is to book. Chromosomes are made of DNA.

Question 18

Describe the Endoplasmic Reticulum

Answer 18

Where RNA is synthesized. A strand of a gene is a template for a piece of mRNA, which leaves the nucleus and goes to the ER. Inside the ER, a ribosome reads the mRNA and can then decide what protein needs to be made.

Question 19

Describe proteins

Answer 19

The product of a cell. First, it is a chain of amino acids, which form pleated sheets or helices. These then fold to form a protein, which can bind to other proteins to make more complex proteins.

Question 20

How are proteins moved?

Answer 20

Packaged and labeled by Golgi bodies then moved along microtubules to final destination: incorporation into membrane, act as an enzyme, or excretion via exocytosis.

Question 21

How do proteins behave when inserted into phospholipid bilayer?

Answer 21

Act as a channel for specific ions, act as gated channels for specific ions which open or close in response to a trigger, or as a pump which exchanges ions moving in opposite directions (sodium potassium pump)