Lecture 9 - Nervous System and Neural Tissue

Question 1

3 anatomical components of the nervous system

Answer 1

1. Central Nervous System
2. Peripheral Nervous System
3. Enteric Nervous System

Question 2

What does the CNS consist of and what is its function?

Answer 2

Brain and spinal cord (connections with the PNS)

It integrates and processes sensory data and motor commands

Question 3

What does the PNS consist of and what is its function?

Answer 3

Nerves (long neuronal processes interacting with non-neuronal cells/organs) and ganglia (groups of cell bodies outside the CNS)

It is directly connected to the CNS

Question 4

What does the ENS consist of and what is its function?

Answer 4

Digestive system

Indirectly connected to the CNS via PNS

Question 5

3 functional classes of the nervous system

Answer 5

1. Sensory neurons (receptors) - pass info from outside into the NS
2. Interneurons (Integrators) - pass info between other neurons
3. Motor neurons (Effectors) - pass info to non neuronal cells

Question 6

Chemical signals

Answer 6

Release of neurotransmitter into synapses (gaps) between neurons

Question 7

Electrical signal

Answer 7

Brief changes in the transmembrane potential of the plasma membrane

Question 8

2 classes of cells in nervous tissue

Answer 8

1. Neurons - transmit information
2. Neuroglia - play supporting roles

Question 9

Glial cells

Answer 9

Located in nervous tissue and protect and maintain neurons

Question 10

4 distinct compartments of a neuron

Answer 10

1. Dendrite - receive inputs from other cells
2. Cell body/soma - receive inputs & produces proteins
3. Axon - transmits action potentials to next cell
4. Axon terminals - converts APs to chemical signal

Question 11

True or False. Information flow within a neuron is unidirectional.

Answer 11

True XD
sensory neuron -> interneuron -> motor neuron

Question 12

4 ways to classify neuron types

Answer 12

1. Multipolar - many dendrites, 1 axon
2. Bipolar - 1 dendrite, 1 axon
3. Pseudo-unipolar - 1 axon connected to soma, dendrite connect to axon
4. Anaxonic - many neurites that act as both dendrite and axon terminal VERY RARE

Question 13

Somatic Nervous System

Answer 13

Motor neurons innervating skeletal muscle
-> sensory neurons innervating integument and skeletomuscular system

Responsible for voluntary (or involuntary, like reflexes) movement

Question 14

Visceral/Autonomic Nervous System

Answer 14

Motor (effector) neurons innervating tissues other than skeletal muscle
-> sensory neurons innervating visceral organs

Question 15

Ependymal cells

Answer 15

Found in the CNS

Line ventricles and secrete cerebrospinal fluid which bathes and cushions the CNS

Question 16

Microglia

Answer 16

Found in the CNS

white blood cells which perform immune functions for the CNS and also help modify connections between neurons

Question 17

Myelinating Glia and what are the 2 types?

Answer 17

Provide electrical insulation in both CNS and PNS

-> wrap cellular processes containing myelin (fats and protein) around the axons of neurons to allow electrical signals to travel rapidly and efficiently
-> 2 distinct types: Schwann cells (PNS) and Oligodendrocytes (CNS)

Question 18

Astrocytes/satellite cells

Answer 18

Astrocyte regulate the extra cellular environment around neurons and also maintain and modify synaptic connections

-> buffer ion concentrations in ECF
-> recycle/buffer neurotransmitters
-> regulate local blood flow (oxygen and nutrient supply)
-> regulate CSF flow

Question 19

If an axon in the PNS is damaged, can it be repaired?

Answer 19

Yes! It can repair and regrow with the help of the local glia.

1. Axon and myelin degenerate and fragment
2. Schwann cells proliferate along axon
3. Axon grows into injury site along Schwann cell path
4. Schwann cells wrap around elongating axon

Question 20

If an axon in the CNS is damaged, can it be repaired?

Answer 20

No :(. Without active axon terminals, the neuron dies through apoptosis

Question 21

True or False: New neurons cannot be born into adulthood

Answer 21

True - it a neuron dies, it will not be replaced

Question 22

What does grey matter consist of?

Answer 22

(Astro/micro)glia
Neuronal somata
Dendrites
Axon terminals

Question 23

What does white matter consist of?

Answer 23

Myelinated axons (connecting one region to another)

Question 24

Withdrawal reflex

Answer 24

It is the result of circuits in the spinal cord grey matter to provide spinal reflexes