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Biology > Homeostasis > Flashcards

Homeostasis Flashcards

1
Q

What two organs make up the CNS? (central nervous system)

A

Brain and spinal cord

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2
Q

Why are reflex actions important?

A

For fast reactions to ensure survival

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3
Q

Why are reflexes so fast?

A
  • Only 2 synapses (3 neurones)
  • Unconscious action
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4
Q

What is homeostasis?

A

Keeping the internal conditions of an organism constant

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5
Q

What are three main conditions controlled by the body?

A
  • Blood sugar
  • Body temperature
  • Water levels
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6
Q

Describe the general pathway of a control system

A

Stimulus –> Receptor –> CNS –> Effector –> Response

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7
Q

What is an effector?

A

Muscles or glands that bring about a response

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8
Q

What is a receptor?

A

Cells that detect stimuli

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9
Q

What is the coordination centre?

A

Areas that receive and process information (usually the CNS)

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10
Q

What is a synapse?

A

A gap between two neurones, allowing impulses to cross

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11
Q

What do neurones do?

A

Carry electrical impulses around the body

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12
Q

Describe the structure of a neurone

A
  • Dendrites (carry impulses towards the cell body)
  • Axon (carries impulses away from the cell body)
  • Myelin sheath (around axon to speed up impulses)
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13
Q

Describe the 3 types of neurone

A
  • Motor neurone
  • Sensory neurone
  • Relay neurone
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14
Q

Compare sensory and motor neurones

A
  • Sensory neurones have cell bodies on their sides, whereas motor neurones have cell bodies on the end
  • Sensory neurones connect to receptors, whereas motor neurones connect to effectors
  • They both have axon
  • They both have myelin sheaths, etc.
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15
Q

What are nodes of Ranvier?

A

Gaps along the myelin sheath, aid the transmission of impulses along the axon

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16
Q

What is the cornea?

A

A clear, tough coating on the front of the eye

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17
Q

What is the iris?

A

Circular muscle that controls the size of the pupil

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18
Q

What is the pupil?

A

Allows light into the eye - dilates and constricts

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19
Q

What is the lens?

A

Flexible structure that changes shape to focus light on the retina

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20
Q

What is the retina?

A

Contains millions of rods and cones that send electrical signals when light touches them

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21
Q

What is the optic nerve?

A

Carries signals from the retina to the brain

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22
Q

What is the suspensory ligament?

A

Holds the lens in place

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23
Q

What is the ciliary muscle?

A

Changes the thickness of the lens when focusing

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24
Q

What is the sclera?

A

White outer layer of the eye, tough to protect the eye

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25
Q

What does the iris (muscle) do?

A

Contracts and relaxes

26
Q

What does the pupil do?

A

Constricts and dilates

27
Q

What is the cerebellum?

A

Controls muscle activity

28
Q

What is the medulla?

A

Controls breathing + heart rate

29
Q

What is the cerebral cortex?

A

Controls conscience

30
Q

Where is the medulla?

A

Above the spinal cord

31
Q

Where is the cerebral cortex?

A

Front of brain

32
Q

Where is the cerebellum?

A

Back of brain

33
Q

How does the eye focus on a near object?

A
  • Ciliary muscles contract
  • Suspensory ligament has low tension
  • Lens becomes short + wide
34
Q

How does the eye focus on a distant object?

A
  • Ciliary muscles relax
  • Suspensory ligament has high tension
  • Lens becomes long + thin
35
Q

What happens to the eye in dim light?

A
  • Iris relaxes
  • Pupil dilates
36
Q

What happens to the eye in bright light?

A
  • Iris contracts
  • Pupil constricts
37
Q

Compare neuronal response and hormonal response

A
  • Neuronal is faster than hormonal
  • Neuronal uses electrical impulses, hormonal uses chemicals
  • Impulses carried along neurones, hormones carried in bloodstream
  • Both help to protect the body
  • Both use receptors
  • Both require stimuli
38
Q

Where is insulin produced and what is it’s function?

A

Produced in the pancreas, removes glucose from blood to be used for respiration or stored (fat + glycogen)

39
Q

Where is glucagon produced and what is it’s function?

A

Produced in the pancreas, breaks down glycogen and fat back into glucose

40
Q

What is type 1 diabetes?

A

Pancreas doesn’t produce insulin

41
Q

What is type 2 diabetes?

A

Body doesn’t respond to insulin

42
Q

Write a method for comparing reaction times of dominant vs non-dominant hand

A
  1. Have one person (Person A) hold out their dominant hand with a gap between their index finger and thumb
  2. Have another person (Person B) hold a ruler vertically with the zero just above the gap in Person A’s hand
  3. Person B will drop the ruler and Person A will have to catch it
  4. Record the measurement their thumb lands on
  5. Repeat this 10 times
  6. Repeat investigation using Person A’s non-dominant hand
43
Q

Why is thermoregulation important?

A

So enzymes inside body don’t denature

44
Q

How does the body deal with cold temperatures?

A
  • Hairs stand up
  • Arteries vasoconstrict (move further from skin’s surface to conserve heat)
  • Sweating reduced
  • Muscles contract and kinetic energy is converted to thermal energy (shivering)
45
Q

How does the body deal with hot temperatures?

A
  • Hairs lie flat
  • Arteries vasodilate (move closer to skin’s surface to lose heat faster)
  • Sweat released to increase evaporation
46
Q

Name three plant hormones

A

Auxins
Gibberellins
Ethene

47
Q

What do gibberellins do?

A

Initiates germination

48
Q

What do auxins do?

A

Increase or decrease growth (shoots vs roots)

49
Q

What does ethene do?

A

Ripens fruit
Controls cell division

50
Q

What does FSH do?

A

Stimulates eggs to mature
Stimulates release of oestrogen

51
Q

What does oestrogen do?

A

Stimulates the uterus lining to regrow after menstruation
Stops release of FSH
Stimulates release of LH

52
Q

What hormone stimulates the production of oestrogen?

A

FSH

53
Q

What does LH do?

A

Stimulates ovulation
(Once ovulation has taken place, LH levels fall again)

54
Q

Where does progesterone come from?

A

The empty egg follicle after ovulation

55
Q

What does progesterone do?

A

Stops production of LH and FSH
Maintains uterus lining

56
Q

What do contraceptive pills contain?

A

Oestrogen and progesterone

57
Q

How does the contraceptive pill work?

A

The oestrogen stops FSH production, meaning no eggs mature
The progesterone maintains a low uterus lining, preventing implantation

58
Q

What are auxins used for in farming?

A

Rooting powder
Weed killer
Tissue culture growth

59
Q

What are gibberellins used for in farming?

A

Promote flowering
Increase fruit size

60
Q

What is ethene used for in farming?

A

Controls ripening of fruit during transport

Biology (7 decks)

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