Lecture 9: Nervous System and Neural Tissue

Question 1

What is the nervous system’s role?

Answer 1

Coordinates the rest of the body: it is specialized for rapid and specific information transfer

Question 2

What are the three anatomical components of the nervous system?

Answer 2

Central Nervous system, peripheral nervous system, enteric nervous system

Question 3

Central Nervous System (CNS)

Answer 3

Found within the vertebrae and cranial bones
- Houses vast majority of all neuronal cell bodies and their processes
- Brain has more neurons than the spinal cord
- Spinal cord has most connections with the PNS

Question 4

Peripheral Nervous System (PNS)

Answer 4

Located outside the skull and spine, but directly connected to the CNS
- Has nerves and ganglia

Question 5

Enteric Nervous System (ENS)

Answer 5

Neural cells within the digestive system, which only indirectly connect to the CNS (via PNS)

Question 6

What are the 3 functional classes based on information transfer?

Answer 6

sensors, integrators, effectors

Question 7

Sensory Neurons (Receptors)

Answer 7

Pass information from outside into the NS

Question 8

Interneurons (integrators)

Answer 8

Pass information between other neurons

Question 9

Motor Neurons (Effectors)

Answer 9

Pass information to non-neuronal cells
- Like myofibres

Question 10

Electrical signals

Answer 10

Information transfer and processing in the nervous system uses electrical signals within excitable cells
- Brief changes in the transmembrane potential of the plasma membrane

Question 11

Chemical Signals

Answer 11

Transfers information between cells (Ach)
- Release of neurotransmitters into synapses (gaps) between neurons

Question 12

Neurons

Answer 12

• Transmit information
• Principal cells of nervous tissue
• Highly POLARIZED CELLS

Question 13

Neuroglia (Glial cells)

Answer 13

• play supporting roles
• about half of all cells in nervous tissue are ‘glial cells’ which protect and maintain neurons

Question 14

Dendrites

Answer 14

Receives input from other cells

Question 15

Axons

Answer 15

Transmits action potentials to next cell
- Axon hillock and Axon initial segment: Starting point for action potentials

Question 16

Cell Body/Soma

Answer 16

Receives inputs and produces proteins

Question 17

What is the flow within a neuron

Answer 17

Unidirectional
- Dendrite to axon

Question 18

Neurite arrangement

Answer 18

Multipolar, bipolar, pseudo-unipolar, anaxonic

Question 19

Multipolar

Answer 19

Many dendrites, one axon

Question 20

Bipolar

Answer 20

One dendrite, one axon

Question 21

Pseudo-unipolar

Answer 21

one axon connected to soma, dendrite connected to axon

Question 22

Anaxonic

Answer 22

Many neurites that act as both dendrite and axon terminals
VERY RARE

Question 23

How to classify different neuron types?

Answer 23

By neurite arrangement or neurotransmitter type (each neuron typically releases a single neurotransmitter chemical from all its axon terminals)

Question 24

Somatic Nervous System

Answer 24

• Motor neurons innervating skeletal muscle
• Sensory neurons innervating integument and skeletomuscular system

Question 25

Visceral/ Autonomic Nervous System

Answer 25

• Motor (effector) neurons innervating tissue other than skeletal muscle
• Sensory neurons innervating visceral organs

Question 26

Types of Glial Cells

Answer 26

• Ependymal cells
• Microglial
• Myelinating cells
• Astrocytes/satellites cells

Question 27

Ependymal cells

Answer 27

• found in CNS ventricles
• Line ventricles and secrete cerebrospinal fluid which bathes and cushions the CNS

Question 28

Microglia

Answer 28

• found in CNS
• White blood cells which perform immune functions for the CNS
  and also help modify connections between neurons

Question 29

Myelinating cells

Answer 29

• Provide electrical insulation in both CNS and PNS
• 2 types: Schwann cells and oligodendrocytes

Question 30

Myellinating Glia

Answer 30

Wrap cellular processes containing myelin (fats+proteins) around the axon of neurons

Question 31

Astrocytes

Answer 31

• CNS
• Metabolic and physiological support
• regulate extracellular environment around neurons and maintain and modify synaptic connections
• Buffer ion conc in ECF, recycle neurotransmitters, regulate local blood flow, regulate CSF flow

Question 32

Satellite cells

Answer 32

• PNS
• Do the same thing as astrocytes CNS in PNS

Question 33

How do neurons die?

Answer 33

• Physical trauma to cell body
• Excitoxicity (excessive excitatory synaptic activity)
• Severing the axon (sometimes)
  -NEW NEURONS CANNOT BE BORN IN ADULTHOOD

Question 34

Damaged axon in the peripheral nervous system

Answer 34

• can repair and regrow with the help of local glia
• Schwann cells promote axon regrowth

Question 35

Damaged axon in the Central Nevous System

Answer 35

• typically cannot repair or regrow
• Without active axon terminals, the neuron dies through apoptosis
• Astrocytes inhibit axon sprouting
• Many parts of the CNS are able to reorganize their synapses and make new local connections between their remaining neurons in order to recover some functions even though tissue is not repaired

Question 36

Grey matter

Answer 36

(Astro/micro)glia, neuronal somata, dendrites, and axon terminals

Question 37

White matter

Answer 37

Myelinated axons (connecting one region to another)

Question 38

Dorsal gray matter

Answer 38

sensory processing

Question 40

Ventral gray matter

Answer 40

motar neuron somata

Question 41

Dorsal white matter

Answer 41

projections to brain, sensory awareness

Question 42

Lateral white matter

Answer 42

descending projections from brain; voluntary motor control

Question 43

Grey matter

Answer 43

simple spinal reflexes such as withdrawal reflex

Question 44

White matter

Answer 44

relays sensory and motor information to and from the brain