Lesson 11: Nervous Tissue and Nervous System

Question 1

What is the basic function of the NS?

Answer 1

To send and receive electrical and chemical signals/ communicating system of the body(sensory input, integration, and motor output)

Question 2

Explain the structural and functional divisions of the nervous system

Answer 2

Central NS: Structural: Brain and Spinal Cord
Peripheral NS: Structural: Cranial and spinal nerves/ Functional- Sensory Division and Motor Division
Motor Division: Somatic and Autonomic
Autonomic: Sympathetic and Parasympathetic

Question 3

What are the components of the neuron and its functions?

Answer 3

Cell body(soma): Contains nucleus; biosynthetic center and receptive regions
Dendrites: Receptive regions
Axon: Impulse generating and conducting region

Question 4

What are the functional classifications of neurons?

Answer 4

1. Sensory: sends a message to ANS
2. Motor: away from ANS to effectors
3. Interneurons: interpretation by ANS

Question 5

What are the neuroglia cells of the CNS?

Answer 5

1. Astrocytes
2. Microglial cells
3. Ependymal cells
4. Oligodendrocytes

Question 6

What are the neuroglial cells of the PNS?

Answer 6

1. Satellite cells

2. Schwann cells

Question 7

What is the function of astrocytes?

Answer 7

Most abundant; functions include playing a role in exchanging b/w capillaries and neurons, supporting neurons, responding to nerve impulses, controlling the chemical environment around neurons, and interpretation

Question 8

What is the function of microglial cells?

Answer 8

Function as immune cells, phagocytosis, and trap debris

Question 9

What is the function of ependymal cells?

Answer 9

Produce and circulate cerebrospinal fluid, line the ventricles

Question 10

What is the function of oligodendrocytes?

Answer 10

Myelinate–>insulate and protect signals neurons are sending

Question 11

What is the function of satellite cells?

Answer 11

Function similar to astrocytes

Question 12

What is the function of Schwann cells?

Answer 12

Function similar to oligodendrocytes

Question 13

Define neuron

Answer 13

A nerve cell designed to transmit info to other nerve cells

Question 14

Define ganglion

Answer 14

A group of neuron cells in the periphery

Question 15

What is resting membrane potential?

Answer 15

Approximately -70 mv; caused by the cytoplasmic side of the membrane being negatively charged relative to the outside; the membrane is said to be polarized

Question 16

What is action potential?

Answer 16

A large transient depolarization event that is generated along the membrane of a muscle cell or an axon of a neuron

Question 17

What is saltatory conduction?

Answer 17

Transmission of an action potential along a myelinated fiber in which the action potentials appears to leap from gap to gap.

Question 18

What is the absolute refractory period?

Answer 18

Period following stimulation during which no additional action potential can be evoked; enforces one-way transmission of nerve impulses

Question 19

What is the purpose of the myelin sheath?

Answer 19

• Protect and electrically insulate axon

- Increase the speed of nerve impulse transmission

Question 20

How is the myelin sheath both formed in the CNS and PNS?

Answer 20

In the PNS: Wrapped by Schwann cells, one cell forms one segment of the axon
In the CNS: Wrapped by oligodendrocytes, each cell can wrap up to 60 axons

Question 21

What is the difference between gray and white matter?

Answer 21

White matter is a region in the brain or spinal cord with dense myelinated fibers, while gray matter contains non-myelinated fibers

Question 22

How are action potentials generated?

Answer 22

1. Resting state: All Na+ and K+ channels are closed, only leakage channels are open
2. Depolarization: Na+ channels open and Na+ goes into the cell, as a result, ICF becomes less negative. At threshold(-55 mv to -50 mv), positive feedback causes opening of all channels
3. Repolarization: Na+ channels are inactivating and K+ channels open. Membrane returns resting membrane potential.
4. Hyperpolarization is caused by K+ continuing to leave the cell

Question 23

What is a synapse?

Answer 23

Functional junction or point of close contact between two neurons or between a neuron and an effector cell.

Question 24

What are neurotransmitters?

Answer 24

Chemical messenger released by neurons that, upon binding to receptors of neurons or effector cells, stimulate or inhibit those neurons or effector cells

Question 25

How are neurotransmitters chemically classified?

Answer 25

Acetylcholine
Biogenic Amines: NE, Dopamine, Serotonin, Histamine
Amino Acids: GABA, Glutamate, Glycine
Peptides: Endorphins, Tachykinis, Somatostatin, CCK
Purines: ATP and Adenosine
Gases and Lipids: “Gasotransmitters”-Nitric Oxide, Carbon Monoxide, Endocannabinoids

Question 26

How are neurotransmitters functionally classified?

Answer 26

Effects: Excitatory(cause depolarization) vs Inhibitory(causes hyperpolarization)
Actions: Direct(bind to and open ion channels)-typically Ach and amino acids vs Indirect(promote long-lasting effects and use second-messenger molecules)-biogenic amines, neuropeptides, and dissolved gases