Download Revision: The Immune and Nervous Systems

Revision: The Immune and
Nervous Systems
Year 9 Biological Sciences
Mrs. Foxbridge
The Immune System
• The immune system has two parts:
• The specific Immune System
• The non-specific immune system
Non-Specific Immunity
• The non specific immune system is innate and
protects you from all pathogens
• It is made up of
1. Skin
2. Mucous lining our nasal passages and airways
3. An enzyme called lysozyme sound in tears
4. Urine – flushes germs from the bladder
5. Stomach – very acidic – also can include
vomiting and diarrhoea to flush out
Specific Immunity
• Specific Immunity is the bodies next line of
defence
• Involves the recognition of antigens and a
reaction to eliminate them
• There are two main types of cells involves in
specific immunity
B-Cells
• Found outside or between cells
• Covered in receptors which look for matching
antigens
• Produce antibodies to target to specific
antigen
• Antibodies bind to antigens and destroy them
then attract macrophages
Anti-bodies
• Protein Molecules in a “Y” shape
• Bind to antigens – hands attach to the antigen
and tail attaches to a phagocyte
T-Cells
• Begin life in the bone tissue and migrate to
the thymus gland
• Attack cells that have become infected
• They signal the cell to self destruct
• Stimulate the formation of B-cells
• Response is not immediate, the body will
suffer symptoms of the disease
T-helper cells
• Secrete cytokines which draw other immune
cells to the site of infection – causes swelling
and inflammation
Memory Cells
• Responsible for the bodies immunity
Phagocytosis
• When a cell engulfs a particle and absorbs it
• Macrophages are large immune cells that
patrol the body for antigens or dead cells to
consume
• Pus forms made of dead pathogens and white
blood cells
The Nervous system
• Allows us to respond to stimuli in a
coordinated way
• There are two main parts of the nervous
system
Central Nervous System
• Consists of the brain and spinal cord
Peripheral Nervous System
• Consists of nerves that connect the sense
organs with the central nervous system
Protection
• The brain and spinal cord are very well
protected by the skull and spinal column
• The peripheral nervous system has some
ability to regenerate
• The central nervous system cannot regenerate
• The cells are so specialised that they cannot
divide and create new cells
Neurons
• Neurons – special cells that carry nerve
impulses
• Impulses travel from the central nervous
system to the peripheral nervous system or
from the peripheral organs to the brain.
Three Types of Neurons
1. Sensory neurons
• Run from various stimuli receptors ie. Taste,
sounds, sight, touch and vision
2. Interneurons
• Found exclusively in the spinal cord and brain
• Stimulated by sensory neurons or other
interneurons
1. Motor Neurons
• Transport impulses from the central nervous
system to the muscles and glands
Synapses
• Where the axon terminal ends and stimulates
another structure
• Synapse may be with another neuron or with
a muscle fibre or gland
Reflex Arc
• Receptors (sensitive nerve endings) are
stimulated and send a nerve impulse along a
sensory neuron to the spinal cord
• Then a connector neuron is stimulated to
carry an impulse to a motor neuron
• Motor neuron stimulates a muscle or gland
Reflex Arc
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Response is rapid
Does not involve the brain
Protects us from injury
Examples: blinking, vomiting, sneezing,
startling