1 10.1: introduction cell types in neural tissue: neurons neuroglial cells (also known as neuroglia,...

15
1 10.1: Introduction Cell types in neural tissue: • Neurons • Neuroglial cells (also known as neuroglia, glia, and glial) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Dendrites Cell body Axon Nuclei of neuroglia © Ed Reschke

Upload: amelia-gillian-caldwell

Post on 31-Dec-2015

222 views

Category:

Documents


2 download

TRANSCRIPT

1

10.1: Introduction

• Cell types in neural tissue:• Neurons• Neuroglial cells (also known as neuroglia, glia, and glial)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Dendrites

Cell body

Axon

Nuclei ofneuroglia

© Ed Reschke

2

Divisions of the Nervous System

• Central Nervous System (CNS)• Brain• Spinal cord

• Peripheral Nervous System (PNS)• Cranial nerves• Spinal nerves

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Brain

(a)

Spinalcord Spinal

nerves

Cranialnerves

3

Divisions of Peripheral Nervous System

• Sensory Division• Picks up sensory information and delivers it to the CNS

• Motor Division• Carries information to muscles and glands

• Divisions of the Motor Division:• Somatic – carries information to skeletal muscle• Autonomic – carries information to smooth muscle, cardiac muscle, and glands

4

Divisions Nervous SystemCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Sensory division Sensory receptors

Motor division

Skeletal muscle

Brain

(a) (b)

Spinalcord Spinal

nerves

Cranialnerves

Central Nervous System(brain and spinal cord)

Peripheral Nervous System(cranial and spinal nerves)

Smooth muscleCardiac muscleGlands

AutonomicNervousSystem

SomaticNervousSystem

5

Functions of Nervous System

• Sensory Function (receiving information)

• Sensory receptors gather information• Information is carried to the CNS

• Integrative Function (deciding what to do about information)

• Sensory information used to create:

• Sensations• Memory• Thoughts• Decisions• Motor Function (acting

on information)• Decisions are acted upon • Impulses are carried to effectors

6

10.3: Description of Cells of the Nervous System

• Neurons vary in size and shape

• They may differ in length and size of their axons and dendrites

• Neurons share certain features:

• Dendrites

• A cell body

• An axon

7

Neuron StructureCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Cell body

Neurofibrils

Nucleus

Nucleolus

Dendrites

Impulse

Nodes of Ranvier

Myelin (cut)

Axon

Axon

Chromatophilicsubstance(Nissl bodies)

Axonalhillock

Portion of acollateral

Schwanncell

Nucleus ofSchwann cell

Synaptic knob ofaxon terminal

8

10.4: Classification of Neurons and Neuroglia

• Neurons vary in function

• They can be sensory, motor, or integrative neurons

• Neurons vary in size and shape, and in the number of axons and dendrites that they may have

• Due to structural differences, neurons can be classified into three (3) major groups:

• Bipolar neurons

• Unipolar neurons

• Multipolar neurons

9

Classification of Neurons: Structural Differences

• Bipolar neurons• Two processes• Eyes, ears, nose

• Unipolar neurons• One process• Ganglia of PNS• Sensory

• Multipolar neurons• 99% of neurons• Many processes• Most neurons of CNS

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Dendrites

Axon Axon

AxonDirectionof impulse

(a) Multipolar

Centralprocess

Peripheralprocess

(c) Unipolar(b) Bipolar

10

Classification of Neurons: Functional Differences

• Sensory Neurons• Afferent (approach)• Carry impulse to CNS• Most are unipolar• Some are bipolar

• Interneurons• Link neurons in CNS• Aka association neurons• Multipolar

• Motor Neurons• Efferent (exit)• Carry impulses away from CNS to effectors• Multipolar

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Central nervous system Peripheral nervous system

Cell body

Interneurons

Dendrites

Axon

Axon

Sensory (afferent) neuron

Motor (efferent) neuron

Cell body

Axon(central process)

Axon(peripheral process)

Sensoryreceptor

Effector(muscle or gland)

Axonterminal

11

Types of Neuroglial Cellsin the PNS

1) Schwann Cells• Produce myelin found on peripheral myelinated neurons• Speed up neurotransmission

2) Satellite Cells• Support clusters of neuron cell bodies (ganglia)

12

Types of Neuroglial Cellsin the CNS

2) Astrocytes• CNS• Scar tissue• Mop up excess ions, etc.• Induce synapse formation• Connect neurons to blood vessels

3) Oligodendrocytes• CNS• Myelinating cell

4) Ependyma or ependymal• CNS• Ciliated• Line central canal of spinal cord• Line ventricles of brain• Keep CSF moving

1) Microglia• CNS• Phagocytic cell

13

Types of Neuroglial CellsCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Microglial cell

Axon

Oligodendrocyte

Astrocyte

Capillary

Neuron

Myelinsheath (cut)

Node ofRanvier

Ependymalcell

Fluid-filled cavityof the brain orspinal cord

14

10.5: The Synapse

• Nerve impulses pass from neuron to neuron at synapses, moving from a pre-synaptic neuron to a post-synaptic neuron.

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Dendrites

Impulse

Impulse

Impulse

Synapticcleft

Axon ofpresynapticneuron

Cell body of postsynaptic neuron

Axon of postsynaptic neuron

Axon ofpresynapticneuron

15

Synaptic Transmission

• Neurotransmitters are released when impulse reaches synaptic knob

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Mitochondrion

Synaptic knob

(a)

Synaptic cleft

Neurotransmitter

Axon

Ca+2

Presynaptic neuron

Direction ofnerve impulse

Synapticvesicles

Cell body or dendriteof postsynaptic neuron

Synapticvesicle

Vesicle releasingneurotransmitter

Axonmembrane

Polarizedmembrane

Depolarizedmembrane

Ca+2Ca+2