B10 Homeostasis/nervous system

Question 1

what do enzymes need in order to work?

Answer 1

very stable conditions

Question 2

what is homeostasis?

Answer 2

the regulation of internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes

Question 3

what is homeostasis used for in humans?

Answer 3

to keep the blood glucose level, temperature and water levels constant

Question 4

what does homeostasis consist of?

Answer 4

automatic control systems that make sure the internal conditions of the body stay constant

Question 5

what do automatic control systems involve?

Answer 5

the nervous systems or hormones

Question 6

what do receptor cells do?

Answer 6

detect changes to the environment
this could be the internal or external environment

Question 7

what is a stimulus?

Answer 7

a change to the environment

Question 8

what is a coordination centre?

Answer 8

it receives and processes the information from the receptor cells

Question 9

what is the job of an effector?

Answer 9

carry out the response (restore the optimum level/condition)

Question 10

what is an effector?

Answer 10

a muscle or gland

Question 11

what is the central nervous system (CNS)?

Answer 11

the brain and spinal cord

Question 12

what is the peripheral nervous system?

Answer 12

the nerves running to and from the CNS

Question 13

what are the parts of a reflex arc?

Answer 13

receptor
sensory neurone
CNS
relay neurone (in the CNS)
motor neurone
effector
response

Question 14

what is a synapse?

Answer 14

a junction between two neurones

Question 15

how do synapses work?

Answer 15

when an electrical impulse reaches the synapse, a chemical is released
this diffuses over the gap (synapse) between the two neurones and triggers an electrical impulse to be sent down the next neurone

Question 16

what do reflexes do?

Answer 16

help protect from danger as they are very rapid

Question 17

what is a reflex action?

Answer 17

an automatic and rapid response to a stimulus

Question 18

what is the independent variable in the reaction time practical?

Answer 18

the person being tested

Question 19

what is the dependent variable in the reaction time investigation?

Answer 19

reaction time

Question 20

what are some control variables in the reaction time investigation?

Answer 20

starting distance between the thumb and the first finger should be kept constant
always measure from the top of the thumb
conditions in the room

Question 21

what are some other possible independent variables for the reaction time investigation?

Answer 21

the effect of practice (a person catches the ruler a large number of times and look to see if the reaction time changes depending on the number of tries)
the hand catching the ruler
if chemicals have an effect on reaction time

Question 22

what does the brain control?

Answer 22

complex behaviours

Question 23

what is the cerebral cortex?

Answer 23

the highly folded outer layer of the brain

Question 24

what is the function of the cerebral cortex?

Answer 24

language
memory
consciousness

Question 25

what is the function of the cerebellum?

Answer 25

it coordinates movement and controls balance

Question 26

what does the medulla control?

Answer 26

heart rate breathing rate

Question 27

what are three parts of the brain?

Answer 27

cerebral cortex medulla cerebellum

Question 28

why is it difficult to study or treat the brain?

Answer 28

it is protected by the skull so difficult to access the structure is complex so it is difficult to figure out which parts do what it is extremely delicate and easy to damage

Question 29

what are the ways to study the brain?

Answer 29

look at patients with brain damage electrical stimulation MRI

Question 30

what is the eye?

Answer 30

a sense organ sensitive to light intensity and the colour of light

Question 31

what is the function of the cornea?

Answer 31

start focusing the light rays

Question 32

what is the function of the lens?

Answer 32

focus the light rays onto the back of the eye

Question 33

what is the function of the retina?

Answer 33

it contains receptor cells that allow us to detect light intensity and colour

Question 34

what does the sclera do?

Answer 34

protects the eye

Question 35

what is the function of the ciliary muscles and suspensory ligaments?

Answer 35

they help change the shape of the lens, allowing us to see distant and near objects

Question 36

what is the pupil?

Answer 36

the space in the centre of the iris which lets light pass through

Question 37

what is the function of the iris?

Answer 37

it controls the size of the pupil

Question 38

what does the iris reflex action do?

Answer 38

it protects the retina from bright light and allows more light into the eye when it is dark

Question 39

how does the iris reflex action work?

Answer 39

if the conditions are dark, the light intensity receptors sense this and send a message to the brain. the brain then sends a signal to certain muscles in the iris to contract, making the pupil larger to let more light into the eye. the opposite happens if conditions are bright

Question 40

what is accomodation?

Answer 40

when the lens in the eye changes shape to focus on distant or near objects

Question 41

what happens when the ciliary muscle is contracted?

Answer 41

the suspensory ligaments loosen. this causes the lens to thicken and refract light more strongly

Question 42

what happens when the ciliary muscles loosen?

Answer 42

the suspensory ligaments are pulled tight this causes the lens to flatten and refract light less strongly

Question 43

what needs to happen to light from distant objects?

Answer 43

it needs to be refracted a relatively small amount

Question 44

what needs to happen to light from near objects?

Answer 44

it needs to be refracted a large amount

Question 45

what can cause hyperopia?

Answer 45

the eyeball is too short so the light is focused behind the retina or the lens becomes less elastic

Question 46

what can be used to treat hyperopia?

Answer 46

convex lenses they partially refract the light before it enters the eye

Question 47

what can cause myopia?

Answer 47

the eyeball can be too long so the light focuses in front of the retina or the lens is too thick

Question 48

what can be used to treat myopia?

Answer 48

concave lenses these partially unfocus the light rays before entering the eye

Question 49

what can also be used to treat vision problems?

Answer 49

hard or soft contact lenses laser surgery changes the shape of the cornea the lens inside the eye can be replaced

Question 50

what controls body temperature?

Answer 50

the thermoregulatory centre in the brain

Question 51

how does the body detect temperature?

Answer 51

the thermoregulatory centre in the brain has receptors sensitive to the temperature of the blood the skin also has temperature receptors which send signals down sensory neurones to the thermoregulatory centre in the brain

Question 52

what does sweat do?

Answer 52

it is released from sweat glands and pools on the surface of the skin when it is evaporated away, it takes energy away from the body and cools it down

Question 53

what is vasodilation? what does this do to the body's temperature and how?

Answer 53

the blood vessels supplying the capillaries dilate so more blood flows through the capillaries this means heat transfers out of the blood, cooling the body down

Question 54

what is vasoconstriciton? what does this do to the body's temperature and how?

Answer 54

the blood vessels supplying blood to the capillaries in the skin constrict less blood now flows through the capillaries so less heat is lost this causes the body to stay warm

Question 55

how does shivering increase the body's temperature?

Answer 55

the skeletal muscles contract to generate energy for this contraction, the cells increase the rate of respiration this releases heat to warm the body