Continued: Structure & Function of Cells of the Nervous system

Question 1

Cell body (soma)

Answer 1

contains nucleus, ribosomes, mitochondria

metabolic work of neuron occurs here

Question 2

dendrites

Answer 2

branching fibers

surface lined with synaptic receptors that bring info into neuron

some also include dendritic spines that increase dendritic surface area

Question 3

Axon

Answer 3

single, thin fiber
transmits nerve impulses toward other neurons, organs, muscles
some covered with myelin sheath
(have presynaptic terminals on their ends)

Question 4

action potential

Answer 4

like a brief pulse- it is a brief electrical OR chemical event that starts at the end of the axon next to the cell body and travels toward the terminal buttons

Question 5

presynaptic terminals

Answer 5

bud at end point of an axon where the release of chemicals to communicate with other neurons occurs
located at synapse

Question 6

synapse

Answer 6

junction between terminal button of an axon and membrane of another neuron

Santiago Ramon y Cajal was 1st to demonstrate individual neurons remained separate (Golgi staining)

Question 7

Neurons- what’s inside

Answer 7

Membrane
Cytoplasm-viscous semiliquid substance inside cell
Cytoskeleton-forms perimeter
Nucleus- contains nucleolus and chromosomes

Question 8

Nucleolus

Answer 8

in nucleus; produces ribosomes

Question 9

Ribosome

Answer 9

site of production of proteins translated from mRNA

Question 10

Chromosome

Answer 10

strand of DNA; carries genetic info

when active, portions of chromosomes/genes produce messenger RNA

Question 11

Messenger Ribonucleic Acid (mRNA)

Answer 11

receives a copy of genetic info from gene
leaves nuclear membrane and attaches to a ribosome
causes production of a protein

Question 12

Why are proteins important in cell functions?

Answer 12

provide structure to cell
act as enzymes (molecule that controls chemical reaction)
can combine 2 substances or break a substance into 2
act as a catalyst- cause chemical reaction w/o being a part of final product

Question 13

mitochondrion

Answer 13

responsible for extracting energy from nutrients

produces ATP-molecule important for cell energy metabolism

Question 14

endoplasmic reticulum

Answer 14

storage reservoir
found in cytoplasm
channel for transporting chemicals through cytoplasm

rough: contains ribosomes; involved with production of proteins secreted by cell
smooth: site of lipid synthesis; provides channels for segregation of molecules involved in various cellular processes

Question 15

golgi apparatus

Answer 15

(like UPS)
form of smooth endoplasmic reticulum 
some complex molecules are made and wrapped here 
wrapping or packaging agent 
produces lysosomes

Question 16

lysosome

Answer 16

small sacs containing enzymes that break down waste products

Question 17

microtubule

Answer 17

part of cytoskeleton involved in transporting substances from place to place w/in cell

Question 18

glia

Answer 18

“nerve glue”
supports cells of the CNS
functions include: nutrients, support, insulation, housekeeping
3 most important: astrocytes, oligodendrocytes, microglia

Question 19

blood brain barrier (BBB)

Answer 19

not an actual structure; not the same throughout entire brain
describes tight junction between walls in blood capillaries
selectively permeable

Question 20

Where is the blood brain barrier weak?

Answer 20

Area postrema

region of medulla; poisons can be detected there; can initiate vomiting

Question 21

How do you cross the blood-brain barrier?

Answer 21

small uncharged molecules (e.g. oxygen, CO2, H20)
molecules that dissolve in fats (vit. A and D, drugs that affect the brain)

For everything else? active transport required
protein-mediated process expending energy to pump chemicals across

Question 22

direct agonist

Answer 22

binds with and activates a receptor

acts like a neurotransmitter

Question 23

direct antagonist

Answer 23

receptor blocker
binds with receptor but does not activate it
prevents neurotransmitter from binding

Question 24

In the brain, most synaptic communication is by…

Answer 24

1. Glutamate- excitatory effects
2. GABA- inhibitory effects
   (Glycine is inhibitory/in spinal cord and lower brain stem)
   These 3 have information-transmitting effects

Question 25

All other neurotransmitters have modulating effects-they activate or inhibit neuronal circuits. What are they?

Answer 25

Acetylcholine- cerebral cortex- learning
Norepinephrine-increases vigilance, enhances readiness
Serotonin- supresses species-typical behavior; reduces impulsivity
Dopamine- activates voluntary movement in some areas, reinforces ongoing behavior in other areas

Question 26

What drugs affect Ach?

Answer 26

Affect rel,ase of Ach: botulinum toxin, black widow spider venom (leads to muscle spasms)
Affect Ach receptors: atropine, curare

Question 27

Monoamines

Answer 27

Catecholamines: Dopamine, norepinephrine, epinephrine (synthesized from tyrosine)
Indolamine: serotonin (synthesized from tryptophan)
Ethylamine: histamine (derived from histidine)

Question 28

What 2 neurotransmitters are affected by addictive substances?

Answer 28

Dopamine and Norepinephrine synapses (example- rats kept pressing lever 2,000x/hour to stimulate DA release)

Question 29

What disease is Dopamine implicated in?

Answer 29

Parkinsons

Question 30

Serotonin synthesis?

Answer 30

Serotonin can’t pass BBB
CNS creates it with tryptophan
enters through diet-serotonergic cells collect it- enzyme transforms it into 5HTP-5HTP enzyme transforms it to serotonin

Question 31

What are the major amino acids?

Answer 31

Glutamate-principle excitatory neurotransmitter in CNS (NMDA receptor important for learning/memory)
GABA- inhibitory (epilepsy may be caused by abnormal GABA system; benzos bind to 2nd site on GABA receptor)
Glycine- inhibitory; in spinal cord and lower brain stem; tetanus bacteria releases chemical that prevents release of glycine- removing this inhibitory effect causes muscles to contract continuously. Strychnine-causes convulsions/death

Question 32

Which cranial nerves are responsible for sensory? Which are motor only? Which are mixed?

Answer 32

Sensory only: Olfactory, Optic
Motor only: Oculomotor
Both: Trochlear, Abducens, Vestibulocochlear, Hypoglossal, Accessory, Trigeminal, Facial, Glossopharyngeal, Vagus

Question 33

Describe vagus nerve

Answer 33

10th cranial nerve- the largest

has parasympathetic efferent (outgoing) fibers to organs of thorax and abdomen