homeostasis and response Flashcards
(32 cards)
what is homeostasis?
the regulation of conditions inside the body to maintain a stable internal environment in response to both internal and external conditions.
what is negative feedback?
the response will reverse or cause the opposite effect of the original stimulus
what does homeostasis include the control of?
blood glucose conc, body temp, water and ion levels.
what do control systems include?
receptors, coordination centres and effectors
what does the receptor do?
they detect stimuli
what do coordination centres do?
they receive and process information from receptors.
what do effectors do?
they bring about responses that restore optimum levels of
what is the nervous system?
receptor cells convert a stimulus into an electrical impulse. this travels along cells called sensory neurons to the central nervous system. here, the information is processed and the appropriate response is coordinated resulting in an electrical impulse being sent along motor neurones to effectors. the effectors carry out the response.
what are examples of effectors carrying out responses?
muscles contracting or glands secreting hormones.
what are reflexes?
automatic responses that take place before you even have time to think
what is the pathway of a reflex arc?
the pain stimulus is detected by receptors. impulses from the receptor pass along a sensory neurone to the CNS. an impulse then passes through a relay neurone. a motor neurone carries an impulse to the effector. the effector then responds.
what’s a synapse?
gaps between 2 neurons
how does the synapse work?
when the impulse reaches the end of the first neurone a chemical is released into the synapse. this chemical diffuses across the synapse. when the chemical reaches the second neuron it triggers the impulse to begin again in the next neurone.
what is the cerebral cortex for?
controls consciousness, intelligence, memory and language and it is the outer part of the brain.
what is the cerebellum for?
controls fine movements of muscles; rounded structure towards bottom/ back of brain.
what is the medulla for?
controls unconscious actions such as breathing and heart rate, found in the brain stem in front of the cerebellum.
why is investigating brain function and treating brain damage and disease difficult?
it is complex and delicate, it is easily damaged, drugs given to treat disease cannot always reach the brain because of the membranes that surround it and it is not fully understood which part of the brain does what.
how can neuroscientists map out the regions of the brain?
studying patients with brain damage by observing changes in an individual following damage on a certain area of the brain and electrically stimulating different parts of the brain. they could also use an MRI scan to create pictures of the brain showing which part of the brain is affected by a tumour or which is active during a specific task.
what is the retina?
layer of light sensitive cells found at the back of the eye. when the light hits this, the cells are stimulated. impulses are sent to the brain, which interprets the information to create an image.
what is the optic nerve?
a nerve that leaves the eye and leads to the brain. it carries impulses from the retina to the brain to create an image.
what is the sclera?
white outer layer which supports the structure inside the eye. it is strong to prevent some damage to the eye.
what is the cornea?
the see-through layer at the front of the eye. it allows light through and the curved surface bends and focuses light onto the retina.
what is the iris?
muscles that surround the pupil. they contract to alter the size of the pupil.
how does the iris alter the size of the pupil?
i’m bright light, the circular muscles contract and the radial muscles relax to make the pupil smaller avoiding damage to the retina. in dim light the circular muscles relax and the radial muscles contract to make the pupil larger so more light can enter for a better image.
