Chapter 11 Flashcards Preview

Anatomy and Physiology > Chapter 11 > Flashcards

Flashcards in Chapter 11 Deck (109)
Loading flashcards...
1

The Nervous System

Controlling and communication system of body
Cells communicate via electrical and chemical signals
-Rapid
-Specific
-Usually cause almost immediate responses

2

Functions of Nervous System

Sensory Input
-Information
Integration
-Processing
Motor Output
-Activation

3

Divisions of Nervous System

Central Nervous System (CNS)
Peripheral Nervous System (PNS)

4

Central Nervous System (CNS)

Contents
-Brain
-Spinal Cord
Location
-Dorsal Body Cavity
Function
-Integration and control center
--Interprets sensory input and dictates motor output

5

Peripheral Nervous System (PNS)

Contents
-Spinal nerves to and from spinal cord
-Cranial nerves to and from brain
Location
-Outside brain and spinal cord

6

2 Functional Divisions Peripheral Nervous System (PNS)

Sensory (afferent) division
Motor (efferent) division

7

Sensory (Afferent) Division of PNS

-Somatic sensory fibers- convey impulses from skin, skeletal muscles, and joints to CNS
-Visceral sensory fibers- convey impulses from visceral organs to CNS

8

Motor (Efferent) Division of PNS

Transmits impulses from CNS to effector organs
-Muscles and Glands

9

2 Divisions of Motor (Efferent) Division

Somatic Nervous System
Autonomic Nervous System

10

Motor Division of PNS: Somatic Nervous System of PNS

Somatic motor nerve fibers
-Conducts impulses from CNS to skeletal muscle
-Voluntary nervous system
--Conscious control of skeletal muscles

11

Motor Division of PNS: Autonomic Nervous System

Visceral motor nerve fibers
Smooth muscle, cardiac muscle, and glands
Involuntary nervous systems
Two functional Subdivisions
-Sympathetic
-Parasympathetic

12

Histology of Nervous Tissue

Higher cellular: little extracellular space
-tightly packed
Two principle cell types
-Neuroglia- Small cell that wraps delicate neurons
-Neurons (nerve cells)- Nerve cells, functional unit

13

Histology of Nervous Tissue: Neuroglia

Astrocytes (CNS)
Microglial Cells (CNS)
Satellite Cells (PNS)
Schwann Cells (PNS)

14

Astrocytes

Most abundant, versatile, and highly branched glial cells
Cling to neurons, synaptic endings, and capillaries

15

Astrocytes Function

-Support and brace neurons
-Play role in exchanges
-Guide migration of young neurons
-Control chemical environment around neurons
-Respond to nerve impulses and neurotransmitters
-Influence neuronal functioning

16

Microglial Cells

-Small, ovoid cells with thorny processes that touch and monitor neurons
-Migrates toward injured neurons
-Can transform to phagocytize microorganisms and neuronal debris

17

Satellite Cells

Surround neuron cell bodies in PNS
Function to similar to astrocytes

18

Schwann Cells

Surround all peripheral nerve fibers and form myelin sheaths in thicker nerve fibers
Regeneration

19

Neurons

Definition
-Structural unit of nervous system
Function
-Conduct impulses
Extreme longevity
-100 years or more
Amitotic- with few exceptions
High metabolic rate
All have cell body and one or more processes

20

Neuron Cell Body (Soma)

Center of neuron
-Synthesizes proteins, membranes, and other chemicals
Spherical nucleus with nucleolus
Most neuron cell bodies in CNS
-Nuclei- clusters of neuron cell bodies in CNS
Ganglia- lie along nerves in PNS
-Most common in Spinal Cord

21

Neuron Processes

Armlike processes extend from body
Tracts
-Bundles of neuron processes in CNS
Nerves
-Bundles of neuron processes in PNS
Two types of Processes
-Dendrites
-Axons

22

Dendrites

In motor neurons
-Hundreds of short, tapering, diffusely branched processes
Receptive (input) region of neuron
-Convey incoming messages toward cell body as graded potentials (short distance signals)

23

Axon: Structure

One axon per cell
-In some axon short or absent
-In other most of length of cell
-Some 1 meter long
Long axons called nerve fibers
Branches profusely at end (terminus)
Distal endings call axon terminals

24

Axon: Functional Characteristics

Conducting region of neuron
Generates nerve impulses
Transmits the Axon Terminal
-Secretory region
-Neurotransmitters released into extracellular space
Carries on many conversations with different neurons at same time
Lacks rough ER and Golgi Apparatus
-Relies on cell body to renew proteins and membrane
-Efficient transport mechanisms
-Quickly decay if cut or damaged

25

Transport Along the Axon

Molecules and organelles are moved along axons
-Anterograde
-Retrograde

26

Anterograde

Away from cell body
Examples
-Mitochondria
-Cytoskeleton elements
-Membrane components
-Enzymes

27

Retrograde

Toward body cell
Examples
-Organelles to be degraded
-Signal molecules
-Viruses
- Bacterial toxins

28

Myelin Sheath

Composed of myelin
-Whitish, protein-lipoid substance
Segmented sheath around most long or large-diameter axons
-Myelinated Fibers
Nonnyelinated fibers conduct impulses more slowly

29

2 Functions of Myelin

Protects and electrically insulates axon
Increases speed of nerve impulses transmission

30

Myelin in PNS

Formed by Schwann Cells
-Jelly roll
-One cell forms one segment of myelin sheath
Myelin Sheath
-Concentric layers of Schwann Cells around axon