Homeostasis-PAPER2 Flashcards
What is homeostasis?
Scientists describe it as maintaining a stable internal environment.
Why is homeostasis important?
Homeostasis is how the body keeps conditions inside it the same. Things it keeps the same are
body temperature at 37°C
the amount of water inside our body
and blood glucose levels
Describe common features of all control systems
Negative feedback ensures that, in any control system, changes are reversed and returned back to the set level.
What is the role of negative feedback?
When something becomes too high or too low, negative feedback brings it back to normal.
What does negative feedback do if we are too hot?
blood vessels in our skin vasodilate (become larger) and we lose heat and cool down.
sweat is produced and evaporates from the skin. This transfers energy into the environment.
what does negative feedback do if we are too cold?
blood vessels in our skin vasoconstrict (become smaller), we lose less heat and our body warms up.
Hairs stand up to trap an insulating layer of air.
You shiver meaning your muscles automatically contract which needs respiration which transfers some energy to warm up the body.
why do internal conditions in our body need to be regulated?
So cells are in the correct conditions to function properly and for enzyme reactions.
All automatic control systems are made up of one of these 3.
Receptors, coordination centres and effectors.
What does a receptor do?
Detects the stimulus
What does the coordination centre do?
receives and processes the information then organises a response.
What does an effector do?
Produces the response which counteracts the change and restores the optimum level
What is a stimulus?
A change in environment
What is a reflex action?
A rapid automatic response that doesn’t involve the conscious brain
What does a relay neurone do?
Connects sensory neurones to motor neurones.
What is the cerebellum responsible for?
muscle coordination
What part of the brain controls consciousness memory, and intelligence?
Cerebral cortex
What does the medulla do?
Controls unconscious activities e.g. breathing and heartbeat.
What makes up the central nervous system?
spinal cord and the brain
What 3 methods do scientists use to study the brain?
MRI Scans, Electrically stimulating the brain or studying people which brain damage.
How do MRI scans work?
By showing a detailed picture of the brain’s structures so you can see which areas of the brain are active whilst doing certain activities.
How does electrically stimulating the brain work?
Pushing a tiny electrode into the tissue and zapping it with electricity. By observing what stimulating different areas of the brain does you can see what their function is.
What consequences are there from messing with the brain?
Electric stimulation has resulted in a treatment for nervous system disorders e.g. muscle tremors caused by parkinsons disease.
However it risks physical damage to the brain or brain function e.g. difficulties with speech.
Name all treatments for vision defects
Glasses
Contact lenses
Laser eye surgery
replacement lens surgery
What does being long sighted mean about you eye?
The eyeball is too short or the lens doesn’t refract the light enough
What does being short sighted mean about your eye?
The eyeball is too long or the lens refracts too much light.
Medical term for long sightedness?
Hyperopia
Medical term for short sightedness?
Myopia
What is the Cornea?
The transparent outer layer at the front of your eye. This refracts light into the eye.
What is the sclera?
A tough supporting wall for the eye.
What is the Lens?
The lens focuses the light onto the RETINA
What does the retina contain?
Receptor cells sensitive to light intensity and colour
What is the iris?
The iris contains muscles that control the diameter of the pupil, and therefore how much light enters.
How is the shape of the lens controlled?
By the ciliary muscles and suspensory ligaments
What does the optic nerve do?
Carries impulses from the receptors on the retina to the brain.
Why do you have an iris reflex?
As very bright light can damage the retina to the reflex protects it
What happens to your eye when you look at something near?
The ciliary muscles contract which slackens he suspensory ligaments and this makes the lens fat which increases the amount by which it refracts light
What happens to your eye when you look at something distant?
The ciliary muscles relax, which allows the suspensory ligaments to tighten which makes the lens thin and means that less light is refracted by a smaller amount.
How does vasodilation cool you down?
As it allows more energy to transfer from the skin to the environment.
How does shivering keep you warm?
As it requires respiration which transfers some energy to warm the body.
Some effectors work antagonistically- what does this mean?
They work together to achieve a very precise response. an example is one effector does heats one cools to get a very accurate temperature
How do hairs standing on end keep us warm?
They stand up and trap an insulating layer of air
How do humans cool down except vasodilation
Sweat evaporates from the skin which transfers energy to the environment.
What does insulin do?
Triggers body cells to take up glucose and triggers muscle cells and the liver to STORE excess glucose. (glycogen)
