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biology > homeostasis > Flashcards

homeostasis Flashcards

1
Q

what is a stimulus

A

change in an animals surroundings

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2
Q

what is a receptor

A

the organ which detects the change

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3
Q

what is an effector

A

muscles are the effectors and they contract

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4
Q

what is the CNS

A

the central nervous system- consists of the brain and the spinal cord and it coordinates all the nervous responses such as moving or reflexes

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5
Q

what are the three types of neurones

A

sensory, relay and motor

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6
Q

what is the order of events of an impulse sent from a receptor to the effector

A
  • impulses from the receptor are sent along the sensory neurone
  • sent to the CNS
    impulse is passed to relay neurones in the CNS
  • impulse is then passed along the effector via the motor neurone
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7
Q

what is the dendrite

A

tree like projections which connect to different neurones

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8
Q

what is the axon

A

long section, electrical impulses travel long distances through this axon

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9
Q

myelin sheath

A

insulates axon and speeds up the transmission of impulse

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10
Q

what is a reflex

A

automated actions which do not involve the brain, fast actions which involve the three neurones

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11
Q

what is a synapse

A

a gap between two neurones where the electrical impulse diffuses across

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12
Q

what is the cornea

A

a curved transparent disc at the front of the eye and does most of the focusing

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13
Q

what is the pupil

A

a circular opening whose size is controlled by the iris

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14
Q

what is the iris

A

a ring of muscle with a hole in the middle. The iris controls how much light enters the eye

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15
Q

what is the lens

A

soft flexible and transparent. shape can be changed to fine tune the focusing of light onto the retina

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16
Q

what are the ciliary muscles

A

a ring of muscle at the edge of the eye which circles the lens. when it contracts the lens gets fatter. when it relaxes the lens gets thinner

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17
Q

what are the suspensory ligaments

A

strong fibres which attach the lens to the ciliary muscles

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18
Q

what is the retina

A

contains light sensitive cells called rods and cones

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19
Q

what is the optic nerve

A

consists of many neurones which carry impulses from the retina to the brain

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20
Q

what is the fovea

A

the region of the retina with the greatest number of cones

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21
Q

what is the conjuntiva

A

a mucous membrane that covers the eye to prevent infection

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22
Q

describe what happens when you look into bright light

A
  • circular muscles contract
  • radial muscles relax
  • iris becomes wider
  • pupil constricts
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23
Q

describe what happens when you look into dim light

A
  • radial muscles contract
  • circular muscles relax
  • iris becomes wider
  • pupil dilates
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24
Q

describe what happens when you focus on a far away object

A
  • ciliary muscles relax
  • suspensory ligaments are pulled tight
  • lens is pulled thin and has a less convex shape
  • less refraction of light
25
Q

describe what happens when you focus on a nearby object

A
  • ciliary muscles contract
  • suspensory ligaments relax
  • lens is not stretched
  • more refraction of light
26
Q

how does hair standing on end help when you are cold

A

hair traps layer of air which provides insulation for conduction for heat

27
Q

how does less sweating help when you are cold

A

less sweat is released therefore less heat loss via evaporation

28
Q

how does constricting the capillaries help when you are cold

A

arterioles supplying the capillaries near the surface of the skin get narrower. Less blood will flow through capillaries near the surface of the skin therefore less heat will be lost by radiation

29
Q

how does hair lying flat help when you are too hot

A

hair lying flat makes sure an insulating layer of air is not formed

30
Q

how does sweating help when you are too hot ( vasoconstriction )

A

when sweat is evaporated heat energy is taken away from the skin as evaporation of water requires energy

31
Q

how does widening the arterioles help when you are too hot ( vasodilation)

A

arterioles supplying the capillaries near the surface of the skin get wider. More blood will through capillaries near the surface of skin therefore more heat will be lost by radiation

32
Q

what is osmoregulation

A

the regulation of water levels within the body to keep rising or falling too much

33
Q

what happens when your water levels are low

A
  • water levels are detected by the hypothalamus in the brain
  • more ADH is sent from the pituitary gland
  • ADH makes the collecting duct in the nephron more permeable
  • more water is reabsorbed back into the body
34
Q

what is positive phototropism

A

growth towards the light

35
Q

negative phototropism

A

growth away from the light

36
Q

positive geotropism

A

growth downwards with gravity

37
Q

negative geotropism

A

growth upwards against gravity

38
Q

what happens when light is shone on the plant from one side

A
  • auxins are produced in the tip of the plant
  • auxins diffuse to the shady side of the plant so they don’t get destroyed
  • the auxins cause the cells on the shady side of the plant to elongate more
  • this results in the plant to grow and bend towards the light
39
Q

what is a hormone

A

a chemical messanger that are made in the glands

40
Q

How are hormones transported

A

in the bloodstream in the plasma

41
Q

What is ADH

A

increases permeability of collecting duct in the nephron so more water reabsorption into the blood

42
Q

Where is ADH released from

A

pituitary gland

43
Q

what is the ADH target organ

A

Kidney

44
Q

What is Insulin

A

convert glucose to glycogen
lowers blood sugar levels

45
Q

Where is Insulin released from

A

the pancreas

46
Q

What is the target organ for insulin

A

Liver

47
Q

What is Adrenaline

A

triggers fight or flight response by making heart beat faster

48
Q

Where is Adrenaline released from

A

adrenal gland

49
Q

What is the target organ for adrenaline

A

heart / liver

50
Q

Descriptions of the endocrine ( hormone ) system
- speed
- length of response
- how it travels
- signal made of
- target

A
  • slow
  • long term response
  • in the blood plasma
  • chemical
  • all around the body
51
Q

descriptions of the nervous system
- speed
- length of response
- how it travels
- signal made of
- target

A
  • fast
  • short term response
  • diffusion, along neurones
  • electrical impulse
  • specific area
52
Q

What is an Auxin

A

plant growth substance

53
Q

How do auxins work

A
  • diffuse to other parts of roots or shoots
  • change the rate of elongation in plant cells
54
Q

How does the plant growth change when light is being shone on one side of it

A
  • sunlight destroys auxins so they diffuse away from the light
  • auxins cause elongation on the shady side of the plant causing shoot to bend towards the light
55
Q

what is positive phototropism

A

shoot grows towards light source

56
Q

what is negative phototropism

A

shoot grows away from light source

57
Q

what is positive geotropism

A

roots grow towards gravity

58
Q

what is negative geotropism

A

roots grow away from gravity

59
Q

how does geotropisms ( auxins in the roots ) work

A
  • auxins inhibit cell growth
  • auxins gather at the bottom of the root because of gravity
  • slows cell growth so root bends down

biology (19 decks)

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