Chapter 2 - Cells And Control Flashcards
What is a stimulus/ are stimuli ?
Any change to the internal (chemical reactions inside body) or external (outside the body) environment
What do receptors do?
Detect stimuli, they are located in the sense organs (eyes, ears, nose, tongue and skin) and are groups of cells.
Give an example of receptors: eg in the eye…
Rod and cone cells are used in the eye to detect changes in light, rods for dimmer black light, cones for colour
What are effectors?
Cells that bring about a response to to stimuli which can be on many different ways, these include muscle cells which contract and glands which secrete hormones
How do receptors communicate with effectors?
Via the nervous system, the hormonal system or sometimes both
What is the CNS? What parts of the body make up this?
The central nervous system, the brain and the spinal cord
What is the nervous system? Hat is it made up of
The system that receptors and effectors mostly use to communicate, it is made up of neurones
What receptors detect a stimuli what do they do?
Send electrical impulses along sensory neurones to the CNS
Where does the CNS send the electrical impulses from a receptor? Then what happens?
To an effector along a motor neurone, the motor neurone responds accordingly
What are the 3 types of neurone?
Motor, relay and sensory
What neurone responds to the electrical impulses from receptors accordingly?
Motor neurones
What is the job of the CNS?
To coordinate a response, a stimulus, receptor and effector is needed for this to happen
What enables the nervous system to bring about very rapid responses?
The high speed of electrical impulses
What is a synapse?
The connection between 2 neurones
How is the electrical impulse passed between 2 neurones over the synapse? Why is this?
Because there is a gap between neurones the nerve signal is transferred by chemicals called neurotransmitters which diffuse across the gap, this chemicals set of a new electrical signal in the next neurone
What are the chemicals transferred across a synapse called?
Neurotransmitters
What is a reflex? What do we have this?
An automatic response to a certain stimuli, they reduce your chance of being injured as it takes less time than waiting for your brain to respond
Give an example of a reflex
When a bright light is shone in your eyes your pupils automatically contact/ get smaller so less light is let in therefore less damage of the eyes occur
What is a reflex arc?
The route the electrical impulse (receptor to effector) takes in a reflex
What is the natural reflex if you get a shock?
Your body releases hormone adrenaline automatically