Bio 168 Nervous System Part 1

Functions of the nervous system include

sensory input, integration, motor output

Sensory input

Info gathered by sensory receptors about internal and external changes

Integration

Processes sensory input and decides on necessary actions

Motor output

Activates muscles and glands to produce a response

Central Nervous System (CNS)

Includes the brain and spinal cord, the integration and command center

Peripheral Nervous System (PNS)

Consists of spinal and cranial nerves transmitting messages to/from CNS

Divisions of Peripheral Nervous System

sensory and motor

Somatic afferent fibers

Convey impulses from skin, muscles, and joints to CNS

Visceral afferent fibers

Convey impulses from visceral organs to the CNS

Somatic nervous system

Allows conscious control of skeletal muscles

Autonomic nervous system (ANS)

Regulates smooth muscle, cardiac muscle, and glands involuntarily

Sympathetic division

Part of ANS that mobilizes body systems during stress

Parasympathetic division

Part of ANS that conserves energy and promotes rest

Neuroglia

cells that support and protect neurons

Astrocytes (CNS)

Provide structural and metabolic support for neurons.

Ependymal cells (CNS)

line cavities of the brain and spinal cord, circulate cerebrospinal fluid

Microglia (CNS)

Act as phagocytes, eating damaged cells and bacteria, act as the brains immune system

Oligodendrocytes (CNS)

Myelinate CNS axons; provide structural framework

Schwann cells (PNS)

Form myelin sheath in the peripheral nervous system

Satellite cells (PNS)

Surround neuron cell bodies in PNS

nuclei

clusters of cell bodies in the CNS

Ganglia

clusters of cell bodies in the PNS

tracts

bundles of axons in the CNS

Nerves

Bundles of neuron fibers (axons) in the peripheral nervous system.

Graded potentials are

Short-lived, incoming, localized changes in membrane potential

myelin sheath

covers the axon of some neurons and helps speed neural impulses

A node of Ranvier (myelin sheath gap)

A gap between successive segments of the myelin sheath where the axon membrane is exposed.

white matter

Whitish nervous tissue of the CNS consisting of neuron axons and their myelin sheaths.

gray matter

Brain and spinal cord tissue that appears gray with the naked eye; consists mainly of neuronal cell bodies (nuclei) and lacks myelinated axons.

structural classification of neurons

multipolar, bipolar, unipolar

functional classification of neurons

sensory (afferent), motor (efferent), interneurons