This is a summary of the grade 11 topic on the human nervous system. It includes the functions and locations of the brain, the different systems explained easily, nervous tissue and a simple reflex arc.
Co-ordinating systems
Systems that allow communication between the receptors and the effectors of the body so that
correct reactions to any change in the environment can be brought about.
Nervous coordinating system
Responds the fastest and is brought about by impulses travelling along nerves.
Endocrine coordinating systems
Slower and is brought about by chemicals called hormones which are carried in the blood.
** The two systems work together to respond to changes in the environment and control conditions in the
body.
NERVOUS SYSTEM
Body’s control and communication center.
Provides a continuous flow of information between the environment, brain, and body.
Enables the body to function.
How does the NS function:
1. Sensory function: sensory receptors detect changes in the external environment and in the
environment within the organism.
2. Integrative function: CNS receives this information and ‘decides’ which effectors need to react to
the stimuli.
3. Motor function: effectors (muscles and glands) bring about appropriate responses.
Stimuli:
Physical or chemical changes in the environment (internal and external) capable of causing a response in
an organism.
Outside body:
Light
Temperature
Sounds
Atmospheric pressure
Inside body:
Blood pressure
Blood pH
Tension in muscles etc.
HUMAN NERVOUS SYSTEM
, A) Central Nervous System (CNS)
B) Peripheral Nervous System (PNS)
Central Nervous System
Made up of a concentrated mass of interconnected neurons (nerve cells), grouped together to
form:
1. Brain
2. Spinal cord
Responsible for processing all the information coming from our senses, keeping our organs and
reflexes functioning and directing our movements, thoughts, and feelings.
CNS protected
3 connective tissue membranes = meninges
Cerebro-spinal fluid = formed from blood plasma in special areas in the walls of the ventricles.
Bony case:
1. Cranium
2. Vertebral column
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