Nervous System
The Nervous System 1. Role of the Nervous system: Receives, processes and transmits information that comes from the various parts of the body and the external world
2. Neurons The nervous system functions with the help of neurons. Neurons are specialized cells that receives and transmits messages Parts of a neuron: Dendrites Cell Body Axon Axon terminals
2. Neurons A) Role of neurons: picks up stimuli, transforms them into nerve impulses and transmits these impulses
***A stimulus is anything that can be perceived by a living organism and that can trigger a reaction. Sound, light, heat, electrical shocks, odors and hormones are examples of stimuli. ***A nerve impulse: Electrical signal transmitted by a neuron Transmission of nerve impulses
2. Neurons B) Characteristics of neurons Neurons can be stimulated They are conductive Consumes a great deal of oxygen and glucose Can live more than 100 years Cannot reproduce itself
C) Parts of the Neuron
Nerve Impulses How it works? The dendrites receives the message or stimuli and transforms it into a nerve impulse The nerve impulse is transmitted along the axon Nerve impulses travel from one neuron to another via neurotransmitters (chemical substance) secreted by axon terminals A synapse is the transition zone between 2 neurons that allows a nerve impulse to be transmitted
D) How it works? Dendrites: receive and transform information into a nerve impulse Axon: Carries impulse to axon terminal Axon Terminal: Via neurotransmitters, passes on the impulse to another neuron or nerve A synapse is the transition zone between 2 neurons that allows a nerve impulse to be transmitted
3. Central and Peripheral Nervous system
A) Central Nervous System Made of the brain and the spinal cord The brain: Cerebrum: command central for voluntary motion, interpretation of sense and of intelligence Cerebellum: center of balance and movement coordination Brain stem: control center of internal stimuli and of involuntary movement Spinal cord: carries information from the various parts of the body to the brain. It is also the reflex center. A reflex is a rapid and involuntary reaction to a stimulus A reflex arc is the path taken by a nerve impulse during a reflex
A) Central Nervous system Parts Function Cerebrum Voluntary motion Thought Interpretation Cerebellum Movement coordination Center of balance Brain Stem Involuntary movement Control of internal stimuli Spinal Cord Reflexes
B) Peripheral Nervous system Connects different parts of the body to the central nervous system Nerves are structures that help transmit information between the central nervous system and various regions of the body There are two main types of nerves: Sensory Motor
4. Passing on a message Sensory receptors Sensory Nerves Picks up stimuli and transforms the stimuli into a nerve impulse Sensory Nerves Transmit information, in the form of a nerve impulse from sensory receptors to the central nervous system Also pick up information from vital organs Analysis from the Central Nervous system Motor Nerves Transmit impulses from the central nervous system to the muscles in order to produce voluntary and involuntary motion
For Example Kicking a soccer ball You see the ball (sight – sensory receptor) The eye transforms the information into a nervous impulse The sensory nerves transmit the impulse to the central nervous system The brain analyses the information The motor nerves send the “kick” impulse from the brain to the leg muscles