The Nervous System

Control; Communication

The nervous system is the master ___ and ___ system of the body

Sensory Input, Integration, Motor Output

Three overlapping functions of the nervous system

Sensory Input

Sensory receptors monitor changes, called stimuli, occurring in and outside the body

Integration

Nervous system processes and interprets sensory input and decides whether action is needed

Red Light Example: Sensory Input

Eyes see the red light

Red Light Example: Integration

Brain interprets red light as needing to stop

Red Light Example: Motor Output

Initiates plantar flexion to press the brake and stop

Endocrine System

Second regulating system of the body, uses hormones

Sensory (Afferent) division

The division of functional nerves that have signals coming in

Motor (Efferent) division

The division of functional nerves that have signals going out

Somatic

Voluntary reactions controlled by nerves. Ex. Putting foot down on pedal

Autonomic

Involuntary reactions controlled by nerves. Ex. Mouth Watering

Three functions of Neuroglia

Support, Insulate, Protect Nuerons

Astrocyte

Braces and anchors neurons, most abundant. Looks like a star.

Microglia

Monitor health of nearby nuerons, dispose of debris, phagocyte. Looks like a spider.

Ependymal

Line cavities of brain and spinal cord, cilia assist with circulation. Look like Spongebob character Plankton

Oligodendrocytes

Wrap around nerve fibers and produce myelin sheaths. “Looks like a Tie Fighter”

Neuroglia differ from Neurons in these ways

Cannot conduct impulses, and can reproduce

Two Neuroglia of the Peripheral Nervous System

Schwann and Satelitte

Schwann

In PNS, forms myelin sheath around fibers

Satellite Cells

In PNS, protect and cushion neuron cell bodies

Cell Body

Nucleus and metabolic center of the cell

Processes

Fibers that extend from the cell body

Synaptic Cleft

Gap between axon terminals and next Nueron

Synapse

Functional junction between nerves where a nerve impulse is transmitted

Nuerolemma

Cell membrane of Neurons

Nueroteansmitter/Acetylcholine

Neurotransmitter used to jump a synapse

Myelin Sheaths

White, fatty material protecting and insulating fibers. Speed nerve impulse transmission. Deposited by Schwann cell in “Cinnamon Roll”

Nuclei

Clustered cell bodies in the CNS

Ganglia

Clustered cell bodies in the PNS

Tracts

Bundles of nerve fibers (neuron processes) in the CNS

Nerves

Bundles of nerve fibers (neuron processes) in the PNS

White Matter

Collections of Myelinated fibers (Insulated)

Gray Matter

Mostly unmyelinated fibers and cell body (Not Insulated)

Other Name for Sensory Neurons

Afferent Neurons

Other name for motor neurons

Efferent Neurons

Sensory (Afferent) Neurons Function

Carry impulses from the sensory receptors to the CNS. Receptors include cutaneous sense organs in the skin for pain, temperature, touch and pressure.

Proprioceptors

Sensory receptors in muscles that detect stretch

Motor (Efferent) Neurons Function

Carry impulses from CNS to viscera and/or muscles or glands

Interneurons or Associated Neurons

Cell bodies located in the CNS that connect sensory and motor neurons

Multipolar Neurons

Structural classification, many extensions from the cell body. All motor and interneurons are this classification. Most common structural classification.

Bipolar Neurons

One axon, one dendrite. Located in special sense organs such as eyes and nose. Rare in adults.

Unipolar Neurons

Having a short single process leaving the cell body. Sensory neurons found in PNS Ganglia. Conduct impulses both toward and away.

Reflex

Rapid, predictable, involuntary responses to a stimulus

Reflex Arc

Neural pathways that carry a stimulus from the PNS to the CNS and then back to the motor neuron again

Five essential components of a reflex arc

Receptor, Sensory/Afferent Neuron, Integration Center, Motor/Efferent Neuron, Effector