Chapter 3: Nervous System’s Functional Units

Question 1

Structure of a neuron

Answer 1

Dendrites (Branching extensions collecting information from other cells

Cell body (Protein synthesis, DNA, etc.)

Axon (Main root, Carries messages to other neurons, Only one axon per neuron)

Question 2

Types of neurons

Answer 2

Sensory neurons
- Sensory receptors to the spinal cord
- Bipolar neurons
- Somatosensory dendrite
- Collects afferent information

Interneurons (association neurons)
- Communicate between sensory and motor neurons

Motor neurons
- Outgoing information from the brain to the muscles
- Reside in the lower brainstem and spinal cord
- All efferent neural information must pass through them to reach the muscles

Question 3

Types of glial cells and their functions

Answer 3

Ependymal cell
Secrete CSF

Astrocyte

TRANSPORT, SUPPORT, BLOOD BRAIN BARRIER

Microglial cells
Immune cells of the brain

Oligodendroglial cells
Produces myelin in the CNS

Schwann cells
Produces myelin in the PNS

Question 4

Genetic mutations

Answer 4

• Errors can arise in the nucleotide sequence when reproductive cells make gene copies
• A mutation may be as small as a change in a single nucleotide base or single nucleotide polymorphism
• Most mutations have negative effects
• BRCA1 - more than 100 mutations have been found in this gene
• Mutations can then be acquired

Question 5

Tay-Sachs disease

Answer 5

• Disorder or lipid metabolism
• intellectual disability, physical changes, and death by about age 5
• Caused by a recessive allele on chromosome 15.
• Common in Ashkenazi Jews

Question 6

Huntington disease & associated genes

Answer 6

• Autosomal disorder that results in motor and cognitive disturbances
• Caused by an increase in the number of CAG (cytosine-adenine-guanine) repeats on chromosome 4
• The buildup of an abnormal version of the huntingtin protein kills brain cells, especially in the basal ganglia and the cortex.

Question 7

Epigenetics

Answer 7

• The environment can allow a gene to be expressed or prevent its expression (phenotype)
• Methanolate (methyl groups) can bind with histones can expressed or block DNA (blocks transcription)

Question 8

Methylation

Answer 8

methyl groups bind to DNA to change the transcription of it

Question 9

Myelination

Answer 9

Glial coating that surrounds axons

Multiple Sclerosis
- Nervous system disorder associated with loss of myelin

Peripheral nervous system
- Microglia and schwann cells help repair neurons

Central nervous system
- Repair does not take place, regrowth may be inhibited