Lab Unit 12 - Intro To Nervous System

Question 1

NEURON

Answer 1

One of two types of cells within nervous tissue. Neurons are large cells that transmit and generate messages in the form of nerve impulses.

Neurons vary widely in size and structure, but most have the following 3 components:

1. Cell body
2. Axon
3. Dendrites

Question 2

3 COMPONENTS OF A NEURON

Answer 2

1. Cell body
2. Axon
3. Dendrites

Question 3

CELL BODY

Answer 3

The cell body is the biosynthetic center of the neuron, containing the nucleus and many of the organelles.

The cell body contains neurofilaments (compartmentalize the rough ER into structures called Nissl bodies). Near the axon and dendrites, neurofilaments for larger neurofibrils.

Cell bodies are often found in clusters.

Question 4

AXON

Answer 4

A single axon exits the cell body at the axon hillock. An initial segment is distal to the axon hillock, with an area known as the trigger zone. The trigger zone generates signals in the form of action potentials that are transmitted to other neurons, muscle cells, and glands.

Question 5

AXON TERMINAL

Answer 5

Axon terminal aka a synaptic bulb. The axon terminal contains synaptic vesicles with transmitters that communicate with the axon’s target cell.

Question 6

DENDRITES

Answer 6

Branching processes found in most neurons. Dendrites receive signals from other neurons. Dendrites can transmit these signals to the neuron’s cell body, but they are NOT capable of generating action potentials.

Question 7

NERVOUS SYSTEM

Answer 7

Composed of the central nervous system (brain and spinal cord) and peripheral nervous system (cranial and spinal nerves)

Question 8

NEUROGLIAL CELLS

Answer 8

The second of two cell types found in nervous tissue. Neuroglial cells are the smaller cells that support neurons. Neuroglial cells outnumber neurons about 50 to 1

Question 9

MULTIPOLAR NEURON

Answer 9

Multipolar neurons are the most common type of neuron. Multipolar neurons have three or more processes- specifically, one axon and two or more dendrites. Most resemble highly branched trees and have hundreds to thousands of dendrites.

Question 10

BIPOLAR NEURONS

Answer 10

Bipolar neurons are rarer than multipolar neurons and are associated with the senses- can be found in the olfactory epithelium and the retina of the eye. Bipolar neurons have one axon and one dendrite.

Question 11

PSEUDOUNIPOLAR NEURONS

Answer 11

Pseudounipolar neurons have only one process. The process branches like a T, into a peripheral process and a central process. Both the peripheral and central process can generate action potentials and are therefore axons. Pseudounipolar neurons are sensory neurons that detect stimuli such as fine touch, pressure, and pain.

Question 12

ASTROCYTES

Answer 12

The most numerous neuroglial cell type in the CNS. Star-shaped cells with perivascular feet that anchor neurons and blood vessels in place, regulate the extracellular environment of the brain, and facilitate the formation of the blood brain barrier.

Question 13

OLIGODENDROCYTES

Answer 13

Oligodendrocytes wrap around the axons of certain neurons in the CNS to form myelin sheath. One oligodendrocyte can myelinated segments of SEVERAL actions in a counterclockwise direction.

Question 14

MICROGLIAL CELLS

Answer 14

Microglial cells are very active phagocytes in the CNS, that clean up debris surrounding neurons, and can degrade and ingest damaged or dead neurons.

Question 15

EPENDYMAL CELLS

Answer 15

Ependymal cells line the hollow spaces of the brain and spinal cord (CNS). They have cilia that beat, which help circulate cerebrospinal fluid.

Question 16

SCHWANN CELLS

Answer 16

Schwann cells form the myelin sheath in the PNS. One Schwann cell can only myelinate a segment of ONLY ONE axon, in a clockwise direction.

Question 17

SATELLITE CELLS

Answer 17

Satellite cells surround the cell bodies of neurons in the PNS. Satellite cells enclose and support the cell bodies, and regulate the extracellular environment around them.

Question 18

NEURILEMMA

Answer 18

The outer edge of the Schwann cell, and contains most of its cytoplasm and the nucleus.

Question 19

NODES OF RANVIER

Answer 19

Nodes of Ranvier are the gaps of unmyelinated segments down an axon.

Question 20

INTERNODE

Answer 20

Internodes are the myelin covered segments down an axon.

Question 21

SYNAPSE

Answer 21

The synapse is the junction where neurons communicate with one another and with their target cells.

Question 22

3 PARTS OF A SYNAPSE

Answer 22

1. Presynaptic neuron
2. Synaptic cleft
3. Postsynaptic neuron

Question 23

AXON TERMINALS

Answer 23

Axon terminals are located in the presynaptic neuron and contain synaptic vesicles with neurotransmitters

Question 24

SYNAPTIC CLEFT

Answer 24

The synaptic cleft is a narrow space that separates the presynaptic neuron and postsynaptic neuron. The synaptic cleft is filled with extracellular fluid, enzymes, and other proteins.

Question 25

POSTSYNAPTIC NEURON

Answer 25

The postsynaptic neuron is the neuron that receives the message. Its plasma membrane contains receptions for neurotransmitters.