1. Fundamentals of the Nervous System and Nervous Tissue11

2. The master controlling and communicating system of the body Functions
Nervous System
The master controlling and communicating system of the body
Functions
Sensory input – monitoring stimuli occurring inside and outside the body
Integration – interpretation of sensory input
Motor output – response to stimuli by activating effector organs

3. Organization of the Nervous System
Central nervous system (CNS)
Brain and spinal cord
Integration and command center
Peripheral nervous system (PNS)
Paired spinal and cranial nerves
Carries messages to and from the spinal cord and brain
Notes from 12/4
Start here

4. Peripheral Nervous System (PNS): Two Functional Divisions
Sensory (afferent) division
Sensory afferent fibers – carry impulses from skin, skeletal muscles, and joints to the brain
Visceral afferent fibers – transmit impulses from visceral organs to the brain
Motor (efferent) division
Transmits impulses from the CNS to effector organs

5. PNS Motor Division: Two Main Parts
Somatic nervous system
Conscious control of skeletal muscles
Autonomic nervous system (ANS)
No conscious control
Regulates smooth muscle, cardiac muscle, and glands
Has two divisions – sympathetic and parasympathetic
12/5 notes end here

6. The two principal cell types of the nervous system are:
Nerve Tissue
The two principal cell types of the nervous system are:
Neurons – excitable cells that transmit electrical signals
neuroglia or glial cells (Supporting cells) – cells that surround and wrap neurons
Provide support & insulation
Promote health and growth
Classwork for 12/6 and 12/7 starts here

7. Structural units of the nervous system
Neurons (Nerve Cells)
Structural units of the nervous system
Composed of a body, axon, and dendrites
Their plasma membrane functions in Electrical signaling

8. Whitish, fatty, segmented sheath around most long axons
Myelin Sheath
Whitish, fatty, segmented sheath around most long axons
It functions to:
Protect the axon
Electrically insulate fibers from one another
Increase the speed of nerve impulse transmission

9. Formed by Schwann cells in the PNS A Schwann cell:
Myelin Sheath
Formed by Schwann cells in the PNS
A Schwann cell:
Envelopes and encloses the axon with its plasma membrane

10. Neuron Functional Classification
Neurons are classified based on structure and function (we will only cover function)
Functional:
Sensory (afferent) — transmit impulses toward the CNS
Motor (efferent) — carry impulses away from the CNS
Interneurons (association neurons) — shuttle signals through CNS pathways
Classwork for 12/6 & 12/7 ends here

11. The Moving Impulse
Notes for 12/8 start
The minimum level of a stimulus that is required to activate a neuron is called a threshold.
A stimulus must be equal to or greater than the threshold to cause a neuron to produce an impulse.

12. The Nerve Impulse
The way the nerve impulse travels through neurons is like how electricity travels through wires.
Nerves generate tiny amounts of electrical charges, based on amounts of sodium ions (Na+) and potassium ions (K+).

13. This temporarily changes the charge of the neuron…
The Moving Impulse
A nerve impulse begins when a neuron is stimulated by another neuron or by its environment.
At the leading edge of an impulse, the sodium gates open and sodium flows into the neuron.
This temporarily changes the charge of the neuron…
Potassium gates then open and allow potassium out of a neuron.
This continues to reverses the charges further, forming an action potential …

14. Restoring the Resting Potential
The sodium-potassium pump then moves sodium out of the cell and potassium into the cell
This restores the original charge across the membrane
12/8 notes stop

16. The movement of Na and K changes the charge across the cell membrane
Quick review
When a stimulus overcomes the threshold a neuron starts an action potential
The action potential is created by moving ions of sodium (Na) and potassium (K)
The movement of Na and K changes the charge across the cell membrane
When the Na and K levels are restored, the charge is reversed and the cell is at rest (resting potential)
12/9 notes

17. Neurons do not touch other neurons.
The Synapse
Neurons do not touch other neurons.
The tiny space between two neurons is called a synapse.
Neurotransmitters are chemicals released by one neuron to transmit an impulse across a synapse and stimulate the next neuron.
12/9 notes