Animal Systems

SAMANTHA RUSSELL

ANIMAL ANATOMY

CHAPTER 1

Nervous System

NERVOUS SYSTEM

Function of the Nervous System

There are four main functions of the nervous system. It detects and processes information, formulates responses, coordinates all body functions, and sends and receives impulses. Impulses are electrical signals that travel through out the nervous system and provide information to the brain.

There are two parts of the nervous the central nervous system and the peripheral nervous system. The central nervous system is made up of the brain and the spinal cord. The spinal cord is the pathway for all impulses going to and from the brain, it connects to the medulla oblongata. The brain, the major organ on the nervous system, is made up of 8 parts: the meninges, cerebrum, cerebellum, brainstem, medulla oblongata, thalamus, hypothalamus, and the pituitary gland.

The peripheral nervous system has nerves that relay information to and from the spinal cord. There are 2 parts to the peripheral nervous system, the sympathetic and the parasympathetic. The sympathetic system is responsible for emergency actions and stress responses, also known as fight or flight. The parasympathetic system seeks to maintain homeostasis. Homeostasis means to maintain balance.

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NERVOUS SYSTEM

Types of Neurons

There are three types of neurons, sensory, connecting or inter, and motor neurons. Each neurons is responsible for some-thing different.

Sensory neurons carry impulses towards the brain and spinal cord. It is responsible for carrying impulses from the stimulus receptors; touch, smell, taste, sound, and vision.

Connecting neurons, also known as inter neurons, carry im-pulses from one neuron to another. It is only found in the spi-nal cord and the brain.

Motor neurons carry impulses away from the central nervous system to muscles and glands and then carries out the re-sponse. While most motor neurons are stimulated by connect-ing neurons some are connected straight to sensory neurons.

There are 7 parts of a neuron; the axons, cell body, dendrites, myelin sheath, schwann cell, node of ranvier, and the axon terminals.

The axon can be over a meter long and is a hairlike extension that conducts impulses.

The cell body houses the nucleus and other organelles, makes for everything in a cell, and it can take over two weeks for ma-terials to reach the axon terminals.

Dendrites are where nerve impulses are generated. They look like short branched fibers.

The myelin sheath and the schwann cell go together. The mye-lin sheath is a fatty sheath and the plasma membrane cover-ing the cell. The Schwann cell is an accessory cell.

The node of ranvier propagates the nerve impulse. When one Schwann cell meets another it is unpro-tected.

The axon termi-nals create syn-apses and is the connection be-tween 2 nerve cells, like a bridge.

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