Section 6 - Coordination and Response P1 Flashcards
What changes do animals respond to?
And why?
-changes in their external environment
-changes in their internal environment(to make sure conditions are always right)
To increase their chance of survival
What changes do plants respond to?
They increase their chance of survival by responding to changes in their environment
What’s a stimulus?
Any change in the internal or external environment is called a stimulus.
What do receptors do?
Receptors detect stimuli.
Receptors in the sense organs are groups of cells that detect external stimulus.
What are the sense organs?
Eyes, ears, nose, tongue, skin
What do effectors do?
And what’re examples of effectors?
Effectors are cells that bring about a response to stimuli.
E.g.
Muscle cells contract
Glands secrete hormones
How do receptors communicate with effectors?
They communicate via the nervous system or the hormonal system or both
What’s the nervous system made up of?
Neurones (nerve cells)
What are the three main types of neurones?
- sensory neurone
- relay neurone
- motor neurone
What’s the CNS made up of?
And what’s its function?
CNS- Central Nervous System
-consists of the brain and spinal cord only
Function- to coordinate the response, coordinated responses always need a stimulus, receptor and an effector
What detects a stimulus, and what happens once a stimulus is detected?
receptors detect a stimulus
- they send electrical impulses along sensory neurones to the CNS
- the CNS then sends electrical impulses to an effector along a motor neurone, the effector then responds accordingly
Why is the nervous system able to bring about very rapid responses?
Because neurones transmit information using high speed electrical impulses
What’s a synapse?
The connection between two neurones is a synapse
How do synapses work?
- the nerve signal is transmitted by chemicals called neurotransmitters which diffuse across the gap
- these chemicals then set off a new electrical signal in the next neurone
What’re reflexes?
Reflexes are automatic responses to certain stimuli
-they can reduce the chances of being injured
What’s a reflex arc?
A reflex action follows this general sequence and does not involve the conscious part of the brain, which makes it much quicker.
What’s the sequence of a reflex arc?
Stimulus Receptor Sensory neurone Motor neurone / CNS Motor neurone Effector Response
What coordinates the response in a reflex?
The spinal cord or an unconscious part of the brain
What’s the process that goes on in a reflex action?
- a stimulus is detected by receptors and an impulse is sent along a sensory neurone to the CNS
- the CNS then passes on the message to a relay neurone
- the relay neurones relay the impulse to a motor neurone
- the impulse then travels along the motor neurone to the effector
- then the response happens
What is the conjunctiva in the eye?
The conjunctiva lubricates and protects the surface of the eye
What is the sclera in the eye?
The sclera is the tough outer layer that protects the eye
What is the cornea in the eye?
The cornea refracts light into the eye.
-it’s transparent and has no blood vessels to supply it with oxygen, so oxygen diffuses in from the outer surface
What is the iris in the eye?
The iris controls the diameter of the pupil and therefore how much light enters the eye
What is the lens in the eye?
The lens focuses the light onto the retina
What is the retina in the eye?
The light-sensitive part, it’s covered in light receptors called rods and cones
- cones are sensitive to colours, not dim light
- rods can’t sense colours, sensitive in dim light