Homeostasis and response Flashcards
What is homeostasis?
The regulation of the conditions inside you body to maintain a stable internal environment, in response to changes in both internal and external conditions
What are the three main components that work together to maintain a steady condition?
Cells called receptors, coordination centers and effectors
What is stimuli?
A change in the environment which the body may need to respond to. his could be light, sound, touch, pressure, pain, chemical or temperature
What happens in the body when the levels of a stimulus are too high or low?
It is detected by the receptors, which then send the information to the coordination centre which organises a response. The effectors respond to counteract the change.
What is the mechanism that restores the optimum level called?
A negative feedback mechanism
What is the problem with the effectors and how is this solved?
They will keep on producing responses which can mean that they can change the level of stimuli too much, but this is detected by the receptors etc.
What does the nervous system do?
What allows you to react to your surroundings and coordinates your behaviour
How does the central nervous system send messages?
It is connected to the body by sensory and motor neurones, which electrical impulses can be transmitted on
How do muscles and glands respond to nervous impulses?
Muscles contract and glands secrete chemical substances called hormones
What are the three types of neurones?
Sensory, motor and relay
What are sensory neurones?
The neurones that carry information in electrical impulses from receptors to the central nervous system
What are relay neurones?
The neurones that send electrical impulses from sensory neurones to motor neurones. These are found in the central nervous system
What are motor neurones?
The neurones that carry electrical impulses from the central nervous system to the effectors
What is a synapse?
The connection between two neurones
How are nerve signals transferred across a synapse?
Chemicals which diffuse across the gap and then set off a new electrical impulse in the next neurone
What are reflexes?
Fast, automatic responses to certain stimuli; bypassed by the conscious brain when a quick response is necessary
What is the brain?
A part of the central nervous system, responsible for complex behaviours such as breathing and is made up of billions of interconnected neurones
What is the cerebral cortex responsible for?
Things like consciousness, intelligence, memory, and language; it is the outer, wrinkly bit
What is the medulla responsible for?
Controls unconscious activities such as breathing
What is cerebellum responsible for?
Muscle co-ordination (looks like a flower)
What are the three methods scientists use to study the brain and how?
Studying patients with brain damage to see the effect of the damaged part, electrically stimulating the brain by using electrodes to see how different parts react and MRI scans that can give a detailed picture of the brain
What is the sclera?
The tough, supporting wall of the eye
What is the cornea?
The transparent outer layer at the front of the eye which refracts light into the eye
What is the iris?
Contains muscles that controls pupil and how much light gets in
What is the lens?
Focuses the light onto the retina
What are the ciliary muscles and suspensory ligaments?
Control shape of lens
What is the optic nerve?
Carries impulses from the receptors of the retina to the brain
What is the iris reflex?
Light receptors detect bright light, so the circular muscles in the iris contract whilst the radial muscles relax, so less can get into the eye
How does the eye look at near objects?
Ciliary muscles contract, which slackens the suspensory ligaments, making the lens more curved and increases the amount of refracted light
How does the eye look at distant objects?
Ciliary muscles relax, which allows the suspensory ligaments to pull tight, making the lens thinner and refracting light less