Notice: To optimize your learning in this course, we advise that you complete the labs and

Intro to the Nervous System Notice: To optimize your learning in this course, we advise that you complete the labs and modules as indicated in the BIOD 152 Lab Schedule.The nervous system receives and processes information and sends out signals to the muscles and glands to elicit an appropriate response. In this way, the nervous system integrates and controls the other systems of the body.In the human nervous system, the central nervous system (Figure below) includes the brain and the spinal cord (dorsal nerve cord), which lie in the midline of the body.

The skull protects the brain and the vertebrae protect the spinal cord. The central nervous system can send signals or impulses to and receive impulses from the peripheral nervous system. The peripheral nervous system includes all nerves not in the brain or spinal cord which are the cranial nerves that connect directly to the brain and the spinal nerves which project from either side of the spinal cord. The peripheral nervous system connects all parts of the body to the central nervous system and can be divided into a sensory or afferent division and a motor or efferent division. The peripheral nervous system receives impulses from the sensory organs via the afferent division and then relays signals or impulses from the central nervous system to muscles and glands via the motor or efferent division. The efferent division can be further divided into the somatic system and the autonomic system. The somatic system nerves control skeletal muscles, skin, and joints. The autonomic system nerves control the glands and smooth muscles of the internal organs and are not generally under conscious control and can be divided into two systems: the sympathetic system which activates and prepares the body for vigorous muscular

activity, stress, and emergencies and the parasympathetic system which lowers activity, operates during normal situations, permits digestion, and conserves energy.

Problem Set 1:

• The function of the nervous system is to integrate and control the other body systems. Explain

how the nervous system does this.the nervous system is divided into the central and peripheral nervous system. Within the peripheral nervous system their is the autonomic system which communicated with smooth muscle and internal organs and glands. Also in the peripheral system is somatic system which communicates with sense organs and voluntary muscles.

• List the 2 parts of the central nervous system.

Brain and spinal cord

• How are the parts of the central nervous system protected?

brain and the vertebrae

• How do the central nervous system and the peripheral nervous system interact?

through signals and impulses

• What is included in the peripheral nervous system?

all the nerves not in the brain or spinal cord

• What are the 2 divisions of the peripheral nervous system?

sensory (afferent) and motor (efferent)

• Describe the movement of nerve impulses in the peripheral nervous system.

Within the peripheral nervous system their is the autonomic system which communicated with smooth muscle and internal organs and glands. Also in the peripheral system is somatic system which communicates with sense organs and voluntary muscles.

• What are the 2 divisions of the efferent division of the peripheral nervous system?

autonomic and somatic systems

• What is controlled by the somatic and autonomic nervous systems?

automatic communicates with smooth muscles, internal organs and glands.somatic communicates with skeletal muscles, skin and joints

• What are the 2 divisions of the autonomic nervous system?

sympathetic and parasympathetic

• What is the function of the sympathetic nervous system?

to arouse and activate muscles for activity, stress and emergency

• What is the function of the parasympathetic nervous system?

To calm and lower activity. Permits digestion and conserves energy Neurons Neurons (Figure below) are nerve cells that vary in size and shape. They do not undergo mitosis (cell division), require enormous amounts of fuel, are able to survive just minutes without oxygen, and can last an entire human lifetime. Neurons all have three parts: the dendrites, the cell body, and the axon.The neuron cell body, which synthesizes all nerve cell products, consists of a large nucleus with surrounding cytoplasm containing the normal organelles. The dendrites are numerous short extensions that emanate from the cell body which receive information from other neurons conducting those nerve impulses toward the cell body. The single axon, on the other hand, conducts nerve impulses away from the cell body to its axon terminals where it is emitted across a synapse to the dendrite of another neuron. Axons can vary in length being very short or as long as three feet, the length of the axon which extends from the bottom of the spine to the big toe.Axons are composed of cells like the cell body but lack rough endoplasmic reticulum, depending on the cell body for necessary proteins. The peripheral nerve axon is coated in short sections called Schwann cells which are mainly composed of a white fatty layer called the myelin sheath rolled around the axon which insulates the nerve fiber from others and increases the speed of nerve impulses. There are also unmyelinated fibers, which are common in the gray matter of the brain and spinal cord, in which the Schwann cells do not wrap around the axon but are just loosely associated with the axon. The Schwann cell insulating sections are not continuous, having gaps between them called Nodes of Ranvier. At these exposed nodes, the nerve impulse is