The Nervous

System

In-tact nervous system in 1925

Do Now:

If you missed class I need you to attend student support to submit the do now.

Objectives:

Evaluate schemata and revise understanding.

Review components of the nervous system

Associate events and responses to coordinating systems.

General divisions of the nervous system are anatomical and physiological.

A. Most of the peripheral nervous system lies outside the brain and spinal cord, carrying sensory information to and motor information away from the central nervous system via spinal and cranial nerves.

1. One subdivision is the somatic nervous system (SNS) whose motor neurons innervate (supply an organ or other body part with nerves) skeletal muscle.

2. The other subdivision is the autonomic nervous system, whose motor neurons innervate glands or smooth or cardiac muscle.

a. The autonomic nervous system is subdivided into the sympathetic and parasympathetic nervous systems, whose functions are antagonistic in many cases.

b. Autonomic fibers emerge from the central nervous system and typically synapse with a second neuron. All synapses and cell bodies in the sympathetic nervous system are at about the same location causing a bulge in the nerve called a sympathetic ganglion. Nerves of the parasympathetic system project to ganglia very close to the organs they control.

i. Sympathetic stimulation results in responses that help the body deal with stressful events.

• dilation of pupils

• dilation of bronchi

• acceleration of heart rate

• acceleration of breathing rate

• release of glucose from liver

• inhibition of digestive functions

• secretion of adrenalin from adrenal glands

• inhibition of secretion of tear glands

ii. Parasympathetic stimulation results in maintenance of homeostasis, digestive processes, and calming following sympathetic stimulation.

• constriction of pupil size

• normal bladder contractions

• return to normal breathing rate

• stimulation of tear glands

• return to normal heart rate

• stimulation of digestive functions (salivation, peristalsis, enzyme secretion)