1. Anatomy - Tuesday 5/12/2015 General Announcements
Student Presentations
Overview PPT
Fetal Pig Brain dissection intro
Work Returned

2. Functions of the Nervous System
Sensory input—gathering information
To monitor changes occurring inside and outside the body
Changes = stimuli
Integration
To process and interpret sensory input and decide if action is needed
Motor output
A response to integrated stimuli
The response activates muscles or glands

4. Structural vs. Functional Classification of the Nervous System
Structural Classification
Describes everything in the entire Nervous system
Breakdown based on structures/components that make up the entire system
Functional Classification
Describes components of the Peripheral Nervous System (not CNS)
Breakdown based on what structures/components DO in the PNS

5. Structural Classification of the Nervous System

6. Structural Classification of the Nervous System
Central nervous system (CNS)
Organs
Brain
Spinal cord
Function
Integration; command center
Interpret incoming sensory information
Issues outgoing instructions

7. Structural Classification of the Nervous System
Peripheral nervous system (PNS)
Nerves extending from the brain and spinal cord
Spinal nerves—carry impulses to and from the spinal cord
Cranial nerves—carry impulses to and from the brain
Functions
Serve as communication lines among sensory organs, the brain and spinal cord, and glands or muscles

8. Functional Classification of the Peripheral Nervous System
Sensory (afferent) division
Nerve fibers that carry information to the central nervous system
Motor (efferent) division
Nerve fibers that carry impulses away from the central nervous system

10. Functional Classification of the Peripheral Nervous System
Motor (efferent) division (continued)
Two subdivisions
Somatic nervous system = voluntary
Consciously controls skeletal muscles
Autonomic nervous system = involuntary
Automatically controls smooth and cardiac muscles and glands
Further divided into the sympathetic and parasympathetic nervous systems

11. Nervous Tissue: Support Cells
Support cells in the nervous system are grouped together as “neuroglia” a.k.a. glial cells
General functions
Support
Insulate
Protect neurons
Schwann cells form myelin sheath in PNS

12. Nervous Tissue: Neurons
Dendrite
Neurons = nerve cells
Cells specialized to transmit messages
Major regions of neurons
Cell body—nucleus and metabolic center of the cell
Processes—fibers that extend from the cell body
Axon
Nucleus
One
Schwann cell
Schwann cells,
forming the myelin
sheath on axon
Axon
terminal

13. Neuron cell body
Dendrite

14. Nervous Tissue: Neurons
Processes outside the cell body
Dendrites—conduct impulses toward the cell body
Neurons may have hundreds of dendrites
Axons—conduct impulses away from the cell body
Neurons have only one axon arising from the cell body at the axon hillock

15. Nervous Tissue: Neurons
Axons
End in axon terminals
Axon terminals contain vesicles with neurotransmitters
Axon terminals are separated from the next neuron by a gap
Synaptic cleft—gap between adjacent neurons
Synapse—junction between nerves

16. Nervous Tissue: Neurons
Myelin sheath—whitish, fatty material covering axons
Schwann cells—produce myelin sheaths in jelly roll-like fashion around axons (PNS)
Nodes of Ranvier—gaps in myelin sheath along the axon

17. Schwann cell
cytoplasm
Schwann cell
plasma membrane
Axon
Schwann cell
nucleus
Myelin
sheath

18. Neuron Cell Body Location
Most neuron cell bodies are found in the central nervous system
Gray matter—cell bodies and unmyelinated fibers
Nuclei—clusters of cell bodies & myelinated axons within the white matter of the central nervous system
Ganglia—collections of cell bodies outside the central nervous system

19. Neuron Cell Body Location
Tracts—bundles of nerve fibers in the CNS
Nerves—bundles of nerve fibers in the PNS
White matter—collections of myelinated fibers (tracts)
Gray matter—collections of mostly unmyelinated fibers and cell bodies

20. Functional Classification of Neurons
Sensory (afferent) neurons
Carry impulses from the sensory receptors to the CNS
Cutaneous sense organs
Proprioceptors—detect stretch or tension
Motor (efferent) neurons
Carry impulses from the central nervous system to viscera, muscles, or glands
Interneurons (association neurons)
Found in neural pathways in the central nervous system
Connect sensory and motor neurons

21. Functional Properties of Neurons
Irritability
Ability to respond to stimuli
Conductivity
Ability to transmit an impulse

22. Action Potential
- the change in electrical-chemical potential (movement of ions) that occurs between the inside and outside of a nerve or muscle fiber when it is stimulated, serving to transmit nerve signals.
Axon of
transmitting
neuron
Receiving
neuron
Action
potential
arrives.
Dendrite
Axon terminal
Synaptic
cleft

23. The neurotransmitter molecules diffuse across the synapse and bind to receptors on the membrane of the next neuron
Transmitting neuron
Vesicle
fuses with
plasma
membrane.
Neurotrans-
mitter is
released into
synaptic cleft.
Synaptic
cleft
Ion
channels
Neurotransmitter
molecules

24. Regions of the Brain Cerebral hemispheres (cerebrum) Diencephalon
Brain stem
Cerebellum

25. Cerebral
hemisphere
Diencephalon
Cerebellum
Brain stem

26. Parietal lobe
Left cerebral
hemisphere
Frontal
lobe
Occipital
lobe
Temporal
lobe
Cerebellum
Brain
stem

27. Regions of the Brain: Cerebrum
Layers of the cerebrum
Gray matter—outer layer in the cerebral cortex composed mostly of neuron cell bodies
White matter—fiber tracts deep to the gray matter
Corpus callosum connects hemispheres
Basal nuclei—islands of gray matter buried within the white matter

28. For your final exam, you should know:
The terms that appear in this powerpoint
The be familiar with the terms in your ‘Overview of the Brain’ packet.

29. Fetal Pig Brain Dissection
HW: watch a video on YouTube that shows how to dissect the brain (see homework website for link)