Nervous Tissue

Question 1

Nervous Tissue

Answer 1

Communication, information gathering, integration, control = rapid response!

Question 2

How is nervous tissue excitable?

Answer 2

Membrane potentials

Question 3

Where does nervous tissue originate?

Answer 3

Neuroectodermal origin

Question 4

How is nervous tissue similar to muscle tissue?

Answer 4

• Can be both a tissue and a cell
• Neuron = cell (axons = nerve fibers)
• Tissue = neurons + supportive tissue

Question 5

Components of nervous tissue

Answer 5

• Endoneurium
• Perineurium
• Epineurium

Question 6

Central Nervous System

Answer 6

• Brain: Cerebrum, Cerebellum, Brain Stem

- Spinal cord

Question 7

Peripheral Nervous System

Answer 7

• Cranial and spinal nerves

- Ganglion (-a)

Question 8

Neurons

Answer 8

• Sensory (afferent)
• Motor (efferent)
• Interneurons (most)

Question 9

Neuron composition

Answer 9

• Cell body (afferent)
• Dendrites (afferent)
• Axon (efferent)
• Synaptic junction (efferent)

Question 10

Supporting cells

Answer 10

• Schwann cells
• Satellite cells
• Glial cells

Question 11

Types of Neurons

Answer 11

• Multipolar
• Bipolar
• Unipolar (aka psudounipolar)

Question 12

Can you see nerve cells histologically?

Answer 12

No

Question 13

Somatic

Answer 13

• Sensory

- Motor

Question 14

Autonomic

Answer 14

Visceral, sympathetic, parasympathetic

• Smooth muscle (hormonal too)
• Cardiac stimulation (+/-)
• Glandular epithelium

Question 15

How do you tell somatic cells from autonomic?

Answer 15

You cannot tell them apart histologically, but can determine which is which based on the location

Question 16

Nerve cell body components

Answer 16

Typical of protein-producing cells

• Nucleus/nucleolus
• RER
• Nissl bodies (substance)
• Mitochondria
• Golgi

Question 17

Axonal hillock

Answer 17

Widened trunk leading out to a neuron

• where nerve impulses originate
• where depolarization occurs

Question 18

Can you see nerve cell bodies histologically?

Answer 18

Yes

Question 19

Processes

Answer 19

Dendrites –> receptors

• Environment
• Other neurons

Axons –> effectors

• Other neurons
• Effector structures

Question 20

Axonal transport

Answer 20

Neurotransmitters

- Slow vs. rapid transport

Question 21

Neurotransmitters

Answer 21

• Formed in nerve cell body
• Kinesin: anterograde microtubules
• Dynein: retrograde mictotubules

Question 22

Synapse

Answer 22

• Junction neuron and effector
• Chemical or electrical gap junctions
• Degradation or re-uptake

Question 23

Types of neurotransmitters

Answer 23

• Acetyl choline
• Norepinephrine
• Epinephrine
• Dopamine
• Serotonin
• GABA

Question 24

Nerves are ____

Answer 24

Collections of hundreds of thousands of neurons

Question 25

Fascicles

Answer 25

- Epineurium: upon the nerves (outer layer) --> can see grossly - Perineurium - Endoneurium: layer right around the axon

Question 26

Neuroglia

Answer 26

Connective tissue cells that support the nerves in the CNS | - Astrocytes, Oligodendrolgia, Microglia, Ependyma

Question 27

Astrocytes

Answer 27

Support, modulate activity, form scar tissue in brain after damage *principle cell type in the CNS

Question 28

Oligodendroglia

Answer 28

Myelin

Question 29

Microglia

Answer 29

Local phagocytes

Question 30

Ependyma

Answer 30

Line the central canal in the brain and spinal cord

Question 31

Connective cells in the PNS

Answer 31

- Schwann cells (make myelin) | - Satellite cells

Question 32

Myelination

Answer 32

Provide insulation --> high lipid content, very little cytoplasm Allows multiple axons to run in the same fascicle and not cross signals - Schwann cells (completely wrap around the axon) and oligodendroglia

Question 33

Unmyelinated fibers

Answer 33

- Slower conduction | - Still "invested" in Schwann cells --> Schwann cells still wrap around axons, but not in multiple layers

Question 34

______ is necessary for the creation of myelin

Answer 34

Multiple layers of Schwann cells

Question 35

Action potential

Answer 35

- Electrochemical depolarization - Axonal hillock toward synapse - Nodes of Ranvier: where a Schwann cell meets the next Schwann cell

Question 36

Organization of CNS

Answer 36

- Gray matter vs. white matter - Brain - Spinal cord

Question 37

Gray and white matter in the CNS

Answer 37

Gray: nerve cell bodies White: axons

Question 38

What are the 3 components of the brain?

Answer 38

- Cerebrum - Cerebellum - Brain stem/ medulla oblongata

Question 39

Meninges

Answer 39

- Dura mater: just underneath the skull, tightly adhered - Arachnoid mater: loose, web like space - Pia mater: innermost layer, really loose connective tissue that distributes blood vessels across the brain/spinal cord

Question 40

Blood brain barrier

Answer 40

Keeps blood off of neurons - endothelium - pericyte: invest connective tissue around the vessels - astrocyte: helps to form BBB

Question 41

Can you see the BBB histologically?

Answer 41

Hard to distinguish capillaries at a histological/ultrastructure level

Question 42

Cerebrum

Answer 42

Higher centers - Gray matter: outer/cortical surfaces - White matter: central area/medulla

Question 43

Gyrus

Answer 43

Multiple outer folds of the brain | --> gyri: one fold on the outside of the brain

Question 44

Sulcus

Answer 44

Grooves separates right from left side of the brain | --> sulci: multiple grooves

Question 45

What animals have no gyri or sulci

Answer 45

Avians

Question 46

Cerebellum

Answer 46

- Coordination - Folia - Gray --> cortex - White --> medulla

Question 47

Molecular layer vs granular layer

Answer 47

Molecular: outermost layer of the cerebellum Granular: inner layer of gray matter in the cerebellum

Question 48

Purkinje fibers

Answer 48

Proms that extend from the molecular layer into the granular layer --> interneurons that communicate between layers

Question 49

Brain stem (medulla oblongata)

Answer 49

Subconscious control - -> reptilian brain - -> nuclei *collections of nerve cell bodies*

Question 50

Spinal cord

Answer 50

Named by vertebrae - Cortex: white matter - Medulla: gray matter - -> switch occurs in lower portion of the brain stem