Introduction to Animals
Animals are eukaryotic heterotrophs that are diploid, reproduce sexually, and develop from embryos. Animal cells are the typical eukaryotic cells with a nucleus and organelles. Cells are organized into tissues which are organized into organs which are organizd into organ systems. The four major animal tissues are epithelial, connective, muscle, and nervous tissue
Introduction to the Nervous System
The nervous system is made up of brains, spinal cord and nerves. The system carries electrical impulses, which is information. The nervous system coordinates activity of muscles, monitors the other organs of the body, and processes inputs from the senses.
Nervous System Cells: Neurons
Neurons are the main cell types of the nervous system. Neurons are specialized for receiving, transmitting, and sending electrical impulses throughout the body. The dendrites of the neuron receive, the axon transmits, and the terminal branches send signals.
The Action Potential
Most neurons are at a resting potential, caused by separation of ions in the cell. An action potential, an electrical impulse that can travel far distances, is sent whenever the neuron passes threshold potential. The synapse is the area between one neuron and another neuron, or one neuron and a muscle cell.
Organization
The nervous system is divided into the central and peripheral nervous system. The central nervous system sends commands which go from the brain to spinal cord to the peripheral nervous system to move the muscles. The peripheral nervous system receives sensory information from the environment, which can send it up the spinal cord to the central nervous system.
Central Nervous System
The central nervous system is made of the brain and spinal cord. The brain is made up of the cerebrum, for learning; the cerebellum, for muscle movement; the hypothalamus, for bodily needs; and the brain stem, for life support systems. The spinal cord is a major highway for transmitting the electrical impulses to and from all parts of the body.
Peripheral Nervous System
The peripheral nervous system is divided into the sensory and motor nervous systems. The sensory nervous system gathers information from the outside environment. The motor nervous system controls muscles. The motor system is divided into the somatic and autonomic system. The somatic system controls voluntary movements. The autonomic system controls involuntary movements, such as heartbeat.
