Lecture 6 (2/5) Flashcards Preview

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Flashcards in Lecture 6 (2/5) Deck (21):
1

Cell Theory

Theodor Schwann, 1839
German zoologist

Proposed all tissues are composed of microscopic units he called cells

2

Cells

The basic functional units of the nervous system
They do the work of the nervous system

2 Distinct Classes
Neurons
Glial Cells

3

Neurons

The information processing agents in the nervous system

Approx 100 Billion in the human nervous system

Has 3 main parts:
Cell body/soma
Dendrite
Axon

4

Cell Body/Soma

One of 3 main parts of a neuron

Contains cyoplasm, which contains organelles

Diffferent types of organelles:
Nucleus
Endoplasmic Reticulum
Golgi Apparatus
Mitochondria
Nissl Body
Neurofibril

5

Nucleus

Type of organelle in the cell body/soma

Relatively large

Contains the machinery for the cell to remain alive and repaired

6

Mitochondria

Type of organelle in the cell body/soma

Contains enzymes involved in the metabolism of the cell

Sometimes referred to as the cell's "powerhouse"

The more the cell has the higher the metabolism of the cell

7

Neurofibril

Type of organelle found in the cell body/soma

Delicate fibers that serve as channels for intracellular communication between organelles

8

Dendrite

One of 3 main parts of a neuron

Has spines on it in a mature brain

Other cells may communicate through these spines

9

Axon (Overview)

One of 3 main parts of a neuron

Part of the cell that is specialized in the transfer of information to other cells/neurons

Extends up to about 1 meter in the human brain

Sends impulses AWAY from the soma only

10

Axon (Anatomy)

Main structures:
Myelin Sheaths
Nodes of Ranvier
Trigger Zone/Initial Segment

3 Main Parts:
Axon Hillock
Axon Proper
Axon Terminal

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Myelin Sheaths

A fatty substance that surrounds large axons at very regular intervals

Essential for high speed information relay

Some diseases target them:
Multiple sclerosis - demyelinates the neurons

12

Nodes of Ranvier

Spaces between the myelin sheaths on an axon

13

Trigger Zone/Initial Segment

An area of the axon that is typically not myelinated and near the soma

14

Golgi Type 1 neurons

"Long distance carriers"

Long axons that carry information from one distant region to another

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Golgi Type 2 neurons

Short axons that process information in a small, limited portion of the brain.

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Axon Hillock

Beginning portion of an axon

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Axon Proper

The middle portion of an axon

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Axon Terminal

The end portion of an axon

Looks like a swollen disc and carries tiny membranes called synaptic vesicles

This is the part of the axon that contacts other neurons and passes info to them

19

Synapse

When an axon terminal makes contact, but doesn't touch

2 Sides
Presynaptic Synapse
Postsynaptic Synapse

20

Synaptic Cleft

Space between the presynaptic synapse and the postsynaptic synapse

21

Synaptic Transmission

The transfer of information