Topic 8 - Coordination in Humans Flashcards
Stimulus
Any change in the internal or external environment
e.g. touch, pain, pressure, temperature, sound, sight, smell, taste
Receptor
A specialised cell that can detect stimuli inside or outside the body
e.g. on the skin, ear, eyes, mouth, nose
Effector
Parts of the body, such as muscles and glands, that produce a response to a detected stimulus
The Nervous System
Allows us to detect stimuli and respond, keeping us alive and well
- Info is sent as nervous impulses - electrical signals that pass along neurons and synapses
- Impulses travel very fast (100m/s), allowing rapid responses to stimuli
- Effects are short term and fast
- Actions/responses are both voluntary and involuntary
- Localised response (specific)
The Endocrine System
Glands and organs that make hormones and release them into the blood so they can travel to tissues and organs all over the body.
- Info is sent through hormones (chemical impulses)
- Slow speed of info transfer
- Effects are long lasting and slow
- Actions/responses are involuntary
- Non-localised response
Hormones
Chemical messengers which are released from organs or glands and travel in the bloodstream to a target cell/organ
Central Nervous System (CNS)
Consists of the brain and spinal cord. Coordinates incoming information from receptors and allows conscious and unconscious muscle contractions.
Order of neutral pathway
stimulus -> receptor -> sensory neuron receives electrical impulse from receptor -> CNS (coordinator) -> motor neuron - carries impulse away from CNS -> effector organ
Reflex arc process
- Hot object (stimulus) is detected by heat receptor in the sensory neuron of the skin
- Sensory neurone sends electrical impulses to the spinal cord (coordinator)
- Impulse bypasses conscious areas of the brain
- Electrical impulse is passed to a relay neurone
- Relay neurone synapses with a motor neurone
- Motor neurone carries an impulse to a muscle in the arm (the effector)
- Muscles in the arm and hand contracts and pull the hand up and away from the hot object (response) to prevent damage
Reflex
a fast, involuntary response to a stimulus
Neurotransmitter
Chemical messengers that carry chemical signals from one neuron to the next target cell.
It gets released from the vesicle at the presynaptic neuron into the synapse and diffuses across, binding with a receptor molecule on the postsynaptic neuron.
electrical impulse -> chemical signal -> electrical impulse
Cornea
A transparent part of the sclera at the front of the eye that refracts (bends) light as it enters the eye
Iris
The coloured part of the eye which contains muscles to increase and decrease the size of the pupil. Controls how much light enters the pupil.
Lens
Transparent disc that can change shape to focus light onto the retina
Retina
A layer at the back of the eye that converts light into electrical signals for brain to process. Contains receptor cells. Rods detect light intensity and cones detect colour.