homeostasis and response

Question 1

what is homeostasis?

Answer 1

the regulation of conditions inside the body to maintain a stable internal environment in response to both internal and external conditions.

Question 2

what is negative feedback?

Answer 2

the response will reverse or cause the opposite effect of the original stimulus

Question 3

what does homeostasis include the control of?

Answer 3

blood glucose conc, body temp, water and ion levels.

Question 4

what do control systems include?

Answer 4

receptors, coordination centres and effectors

Question 5

what does the receptor do?

Answer 5

they detect stimuli

Question 6

what do coordination centres do?

Answer 6

they receive and process information from receptors.

Question 7

what do effectors do?

Answer 7

they bring about responses that restore optimum levels of

Question 8

what is the nervous system?

Answer 8

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.

Question 9

what are examples of effectors carrying out responses?

Answer 9

muscles contracting or glands secreting hormones.

Question 10

what are reflexes?

Answer 10

automatic responses that take place before you even have time to think

Question 11

what is the pathway of a reflex arc?

Answer 11

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.

Question 12

what’s a synapse?

Answer 12

gaps between 2 neurons

Question 13

how does the synapse work?

Answer 13

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.

Question 14

what is the cerebral cortex for?

Answer 14

controls consciousness, intelligence, memory and language and it is the outer part of the brain.

Question 15

what is the cerebellum for?

Answer 15

controls fine movements of muscles; rounded structure towards bottom/ back of brain.

Question 16

what is the medulla for?

Answer 16

controls unconscious actions such as breathing and heart rate, found in the brain stem in front of the cerebellum.

Question 17

why is investigating brain function and treating brain damage and disease difficult?

Answer 17

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.

Question 18

how can neuroscientists map out the regions of the brain?

Answer 18

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.

Question 19

what is the retina?

Answer 19

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.

Question 20

what is the optic nerve?

Answer 20

a nerve that leaves the eye and leads to the brain. it carries impulses from the retina to the brain to create an image.

Question 21

what is the sclera?

Answer 21

white outer layer which supports the structure inside the eye. it is strong to prevent some damage to the eye.

Question 22

what is the cornea?

Answer 22

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.

Question 23

what is the iris?

Answer 23

muscles that surround the pupil. they contract to alter the size of the pupil.

Question 24

how does the iris alter the size of the pupil?

Answer 24

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.

Question 25

what are ciliary muscles and suspensory ligaments?

Answer 25

hold the lens in place and control its shape.

Question 26

how does the eye focus on a near object?

Answer 26

the ciliary muscles contract, the suspensory ligaments loosen, so the lens is thicker and more curved refracting the light more

Question 27

how does the eye focus on a distant object?

Answer 27

the ciliary muscles relax and the suspensory ligaments tighten, so the lens then becomes thinner so light it refracted less

Question 28

what is short sightedness called?

Answer 28

myopia

Question 29

when does myopia occur?

Answer 29

when the lens is too curved, so distant objects appear blurry.

Question 30

what is long sightedness called?

Answer 30

hyperopia

Question 31

when does hyperopia occur?

Answer 31

when the lens is too flat, so if cannot refract light enough.

Question 32

what are the methods for treating myopia and hyperopia?

Answer 32

spectacle lenses, contact lenses, laser eye surgery, replacement lens.