Chapter 13 provides knowledge of nervous system. The following will be discussed in this chapter: Nervous tissue, the central nervous system, the limbic system and higher mental functions, the peripheral nervous system, drug abuse, homeostasis. | Chapter 13 Biology 25: Human Biology Prof. Gonsalves Los Angeles City College Loosely Based on Mader’s Human Biology,7th edition Functions of Nervous Tissue 1. Sensory Input: Conduction of signals from sensory organs (eyes, ears, nose, skin, etc.) to information processing centers (brain and spinal cord). 2. Integration: Interpretation of sensory signals and development of a response. Occurs in brain and spinal cord. 3. Motor Output: Conduction of signals from brain or spinal cord to effector organs (muscles or glands). Controls the activity of muscles and glands, and allows the animal to respond to its environment. Nervous System Processes and Responds to Sensory Input Cells of Nervous Tissue 1. Neuron: Nerve cell. Structural and functional unit of nervous tissue. Carry signals from one part of the body to another. 2. Supporting cells: Nourish, protect, and insulate neurons. There are roughly 50 supporting cells for every neuron. In humans, Schwann cells wrap around the axons of neurons, forming a myelin sheath that is essential for transmission of nerve impulses. Neuron Structure Cell body : Contains nucleus and most organelles. Dendrites: Extensions that convey signals towards the cell body. Short, numerous, and highly branched Axon: Extension that transmits signals away from the cell body to another neuron or effector cell. Usually a long single fiber. Axon is covered by a myelin sheath made up of many Schwann cells that are separated by small spaces (Nodes of Ranvier). Structure of the Neuron Neuron Structure Myelin sheath and nodes of Ranvier greatly speed up nerve impulses, which jump down axon from node to node. Speed of signal Myelinated axon 100 meters/second Unmyelinated axon 5 meters/second Multiple sclerosis: A disease in which a person’s immune system destroys the myelin sheaths on their neurons. Loss of muscle control Impaired brain function Death Central vs. Peripheral Nervous System Central Nervous System (CNS): Brain & spinal cord. Processing . | Chapter 13 Biology 25: Human Biology Prof. Gonsalves Los Angeles City College Loosely Based on Mader’s Human Biology,7th edition Functions of Nervous Tissue 1. Sensory Input: Conduction of signals from sensory organs (eyes, ears, nose, skin, etc.) to information processing centers (brain and spinal cord). 2. Integration: Interpretation of sensory signals and development of a response. Occurs in brain and spinal cord. 3. Motor Output: Conduction of signals from brain or spinal cord to effector organs (muscles or glands). Controls the activity of muscles and glands, and allows the animal to respond to its environment. Nervous System Processes and Responds to Sensory Input Cells of Nervous Tissue 1. Neuron: Nerve cell. Structural and functional unit of nervous tissue. Carry signals from one part of the body to another. 2. Supporting cells: Nourish, protect, and insulate neurons. There are roughly 50 supporting cells for every neuron. In humans, Schwann cells wrap around the axons of .
