University:
Davenport University
Course:
BIOL 115 | Anatomy and Physiology with Human Disease I
Academic year:

2022
Views:

368

Pages:

6
Author:

Alexa Livingston

12.1 Overview of the Nervous System 1 Expected Learning Outcomes: • Describe the overall function of the nervous system. • Describe its major anatomical and functional subdivisions. 2 Overview of the Nervous System 2 Endocrine system and nervous system maintain internal coordination • Endocrine system communicates by means of chemical messengers (hormones) secreted into to the blood • Nervous system utilizes neurons (nerve cells) to send messages from cell to cell by electrical and chemical means; occurs in three steps: • 1. It receives stimuli from external environment and transmits messages to central nervous system (CNS) • 2. The CNS processes the information and determines response • 3. CNS issues commands to muscle and gland cells to carry out response 3 Overview of the Nervous System 3 Nervous system has two major anatomical subdivisions: • Central nervous system (CNS)— brain and spinal cord • Peripheral nervous system (PNS)—nerves and ganglia • Nerve—a bundle of nerve fibers (axons) wrapped in fibrous connective tissue • Ganglion—a knot-like swelling in a nerve where neuron cell bodies of PNS are concentrated Figure 12.1 4 Overview of the Nervous System 4 Functional divisions of peripheral nervous system: • Peripheral nervous system is functionally divided into sensory and motor divisions, each with somatic and visceral subdivisions • Sensory (afferent) division—carries signals from receptors (sense organs) to CNS • Somatic sensory division—carries signals from receptors in the skin, muscles, bones, and joints • Visceral sensory division—carries signals from the viscera (heart, lungs, stomach, and urinary bladder) 5 Overview of the Nervous System 5 Functional divisions of peripheral nervous system (continued): • Motor (efferent) division—carries signals from CNS to effectors (glands and muscles that carry out the body’s response) • Somatic motor division—carries signals to skeletal muscles; causes voluntary muscle contraction and automatic reflexes • Visceral motor division (autonomic nervous system, ANS)— carries signals to glands, cardiac and smooth muscle; no voluntary control; responses called visceral reflexes • • • Sympathetic division of ANS stimulates and prepares the body for action Parasympathetic division of ANS has a calming effect on the body An enteric plexus within digestive tract wall enables coordination and communication within digestive tract 6 Divisions of the Nervous System Figure 12.2 7