gcse biology homeostasis

Created by

Rachel

Cards (47)

What is homeostatis? 
The regulation of the conditions in our body maintaining stable internal environment
What does it do?
Responds to any change in internal or external conditions
What are the 3 main components in automatic control systems? 
Receptors, coordination centres and effectors
What is a stimulus? 
A change in your environment than requires a response
Give some examples of stimuli?
Light, sound, touch, pressure, pain, chemical or temperature
What do the receptors do? 
Detect the stimulus when either temp or water is high or low
What happens after the receptors?
Receptors send messages to the cns which organise a response to the effector
Give examples of the central nervous system?
The brain or spinal cord
How is the CNS connected to the rest of the body?
Through sensory and motor neurones
What is an effector?
Muscles or glands that bring about a response
What do the muscles and glands do in response?
Muscles contract and glands secrete chemical substances(hormones)
What is a sensory neurone?
Neurones that carry information from the receptors to the cns
What is a relay neurone?
Neurones that carry impulses from the sensory to the motor neurones
What is a motor neurone? 
Neurones that carry information from the cns to the effectors
What is the nervous system? 
It is what allows you to react to your surroundings
What is a synapse? 
It is the nerve signal being transferred by chemicals which move across the gap, sending a electrical signal to the next neurone
What is a reflex arc?
The passage of the information, that brings around a response
Responses that reduce body temp-
Hairs lie flat, sweat and blood vessels get wider(vasodilation)
Responses that increase body temp-
Hairs stand up, no sweat, shivering and blood vessels constrict(vasoconstriction)
What is the body's core temp?
37 degrees c
What is the sclera?
The tough supporting wall of the eye
What is the cornea?
Outer layer, bends light into the eye
What is the pupil?
The hole in the centre where light enters
What is the iris?
Controls the diameter of the pupil and how much light enters
What is the retina?
Contains receptor cells- one sensitive to light intensity and the other is colour
What is the lens?
Focuses the light into the retina
What is the ciliary muscles and suspensory ligaments?
Control shape of the lens
What is the optic nerve?
Carries impulses from the receptors on the retina to the brain
What happens when bright light enters?
The circular muscles contract and the radial muscles relax, reducing the amount of light that enters
What happens in dim light?
The radial muscles contact and the circular muscles relax
What is long sightedness?
lens or muscles not powerful enough to bring light to focus on retina. light vocal point is behind retina (convex lens)

bottom diagram is with corrective lenses
What is short sightedness?
naturally too powerful lens, unable to focus on distant objects, refracts light too much(concave lens)

bottom diagram is with corrective lenses
eye lenses when looking into distance
for distant objects the light does not have to be refracted by a big angle

correct diagram is first one
eye lenses for near objects
For near objects the light has to be refracted through a big angle. ciliary muscles contract making the lens thicker

looks like a diamond on its side
What is the brain made from?
Millions of interconnected neurones
What is the brain in charge of?
It is in charge of our complex behaviours, controls and coordinates everything we do
What is the cerebral cortex?
The outer wrinkly layer of the brain, controls consciousness, memory and language
What is the medulla?
The base, controls unconscious activities like breathing, movement in the intestines and heartbeat
What is the cerebellum?
At the back, responsible for muscle contraction & balance
what is the hypothalamas
controls homeostasis and pituitary gland