B1.2 Nerves and hormones Flashcards
The nervous system enables humans to
React to their surroundings and coordinate their behaviour
Stimulus
Change in environment
Receptors detect
Stimuli
Receptors in the eyes are sensitive to
Light
Receptors in the ears are sensitive to
Sounds and changes in position, enable us to keep our balance
Receptors on the tongue are sensitive to
Chemicals which enable us to taste
Receptors in the nose are sensitive to
Chemicals which enable us to smell
Receptors in the skin are sensitive to
Touch, pressure, pain and temperature changes
Light receptor cells have a
Nucleus, cytoplasm and cell membrane
A stimulus can be
Light, sound, touch, pressure, pain, chemical or a change in position or temperature
The central nervous system consists of
The brain and the spinal cord
Neurones transmit information as
Electrical Impulses
Sensory neurones
Nerve cells that carry signals as electrical impulses from the receptors to the central nervous system
Relay neurones
Nerve cells that carry signals from sensory neurones to motor neurones
Motor neurones
Nerve cells that carry signals from the central nervous system to the effector muscles or glands
Effectors - muscles
Contract in response to a nervous impulse
Effectors - glands
Secrete hormones as a response to a nervous impulse
Reflex actions are
Automatic and rapid
First stage of a simple reflex action
A receptor detects a stimuli. Impulses are sent from the receptor along a sensory neurone to the central nervous system
Second stage of a simple reflex action
At a synapse between a sensory neurone and a relay neurone in the central nervous system, a chemical is released that causes an impulse to be sent along a relay neurone
Third stage of a simple reflex action
A chemical is then released at the synapse between a relay neurone and motor neurone in the central nervous system, causing impulses to be sent along a motor neurone to the effector that brings about the response
Fourth stage of a simple reflex action
The effector (either a muscle or a gland) responds by contracting or by secreting chemical substances
Synapse
The connection between two neurones. The nerve signal is transferred by chemicals which diffuse across the gap
What is the name of the passage of information in a reflex (receptor to effector)?
The reflex arc
What conditions in your body need to be controlled?
Ion content, sugar content, water content and temperature
What is ion content regulated by?
The kidneys
How is ion content regulated?
It is removed via the skin when we sweat and through the kidneys in the urine
How is water content regulated?
Leaves the body via the lungs when we breathe out, via the sweat and via the kidneys in the urine
Why is temperature controlled?
To maintain the temperature at which enzymes work best