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Biology Paper 2 > Homeostasis & Response > Flashcards

Homeostasis & Response Flashcards

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1
Q

What is the central nervous system?

A

It is made up of the brain and spinal cord. It allows information to be processed and acted upon. It is made up of the brain and spinal cord.

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2
Q

What is the role of a motor neurone?

A

It transmits signals to effectors to coordinate a response

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3
Q

What is the purpose of the cerebellum?

A

Controls balance and muscle coordination of movement

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4
Q

What is a Voluntary/involuntary response?

A

A VOLUNTARY response is when the brain has to decide on a response but an INVOLUNTARY response is automatic.

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5
Q

What is a synapse?

A

When two neurones meet, the tiny gap is called a synapse.

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6
Q

What is the function of the cerebral cortex?

A

It controls memory, personality, language and conscious thought

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7
Q

What are the difficulties of investigating brain function?

A

The complexity and delicacy of the brain makes it hard to investigate and treat brain disorders

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8
Q

What is the role of a sensory neurone?

A

It transmits signals from receptors to the CNS.

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9
Q

What is the purpose of the medulla?

A

It controls heart rate and breathing rate

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10
Q

How does the eye focus on a near object?

A

To focus on a near object:
• the ciliary muscles contract
• the suspensory ligaments loosen
•the lens is then thicker and refracts light rays strongly

For an object far away > opposite

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11
Q

How is the brain investigated?

A
  • MRI brain scans
  • Studying patients with brain damage
  • Electrical stimulation of parts of the brain
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12
Q

What is the role of a relay neurone?

A

It transmits signals between neurones

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13
Q

Why are reflex actions important?

A

Because they are automatic and rapid and they do not involve the conscious part of the brain.

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14
Q

How does the body detect a change in temperature?

A

Temperature receptors in the skin detect changes in the external temperature. They pass this information to the processing centre in the brain, called the hypothalamus.

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15
Q

What happens when the body temp is too hot?

A

The blood vessels supplying the skin capillaries dilate causing more blood to flow nearer the surface of the skin which increases heat loss (vasodilation)

The body sweats - which increases heat loss due to the large amount of heat energy required to evaporate the water.

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16
Q

What is a stimulus?

A

Something that is detected by receptors and causes impulses to be sent along the sensory neurone to the CNS. e.g been sting or burning hand

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17
Q

Which part of the brain is responsible for the control of body temp?

A

Sensory and relay neurones transmit this information as impulses to the thermoregulatory centre in the brain

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18
Q

What is a hormone?

A

Hormones are chemicals secreted by glands in the body. Different hormones affect different target organs.

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19
Q

How can vision defects be corrected?

A
  • contact lenses
  • laser eye surgery
  • replacement lens surgery
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20
Q

What is the role of the pituitary gland?

A

Produces many hormones that regulate body conditions

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21
Q

What happens when the body temp is too cold?

A

The blood vessels supplying the skin capillaries constrict, causing less blood to flow nearer the surface of the skin causing a reduce in heat loss (vasoconstriction)

The body shivers - the twitching of muscles generates additional heat as their contraction causes the muscles to respire thus releasing energy to warm the body.

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22
Q

What is the medical term for short and long sightedness?

A

Short- myopia

Long-hyperopia

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23
Q

What is the role of the thyroid?

A

Produces thyroxine which regulates the rate of metabolism, heart rate and temperature

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24
Q

What is the role of testes?

A

Produces testosterone which controls puberty and sperm production In males

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25
Q

What are the differences between nerves and hormones?

A

Nerves

  • very FAST action
  • act for a SHORT TIME
  • act on a PRECISE AREA

Hormones

  • SLOWER action
  • act for a LONG TIME
  • act in a GENERAL way
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26
Q

What is the role of the adrenal gland?

A

Produces adrenaline which prepares body for ‘flight or fight’ response

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27
Q

How can type 1 diabetes be treated?

A

By insulin therapy- several injections of insulin at meal times which makes sure glucose is removed from blood quickly to stop level getting too high

28
Q

What is the role of the pancreas?

A

Produces insulin which regulates blood glucose level

29
Q

What is the role of the ovaries?

A

Produces oestrogen which is involved in the menstrual cycle

30
Q

What is the function of kidneys?

A

Make urine by taking waste products out of your blood. The substances are filtered out of the blood as it passed through the kidneys (filtration). Useful substances like glucose, some ions and right amount of water are absorbed back into the blood (selective reabsorption)

31
Q

What is type 1 diabetes?

A

Where the pancreas produces little or no insulin. Blood glucose level can rise to a dangerously high level.

32
Q

What is oestrogen?

A
  • produced in ovaries
  • causes the lining of the uterus to grow
  • stimulates the release of LH and inhibits release of FSH
33
Q

How are kidney transplants used? + one disadvantage?

A

Healthy kidneys planted from people who have died recently or a match that is alive. Kidneys can be rejected by the immune system.

34
Q

What is type 2 diabetes?

A

Where a person becomes resistant to their own insulin. Can cause a persons blood sugar level to rise to a dangerous level.

35
Q

How can type 2 diabetes be treated?

A

Controlled by eating a carbohydrates controlled diet and regular exercise to avoid becoming over weight

36
Q

What is FSH?

A
  • produced in pituitary gland
  • causes an egg to mature in one of the ovaries
  • stimulates ovaries to produce oestrogen
37
Q

How is water content regulated?

A
  • NEGATIVE FEEDBACK COUNTERACTS CHANGE
  • a receptor in the brain detects that the water content is too high
  • the coordination centre in the brain receives the information and coordinates a response
  • the pituitary gland releases less ADH so less water is reabsorbed from the kidney turbules

(If water content is too high)

38
Q

What is LH?

A
  • produced by the pituitary gland

- stimulates the release of an egg at day 14 (ovulation)

39
Q

What happens if the kidneys don’t work properly?

A

Waste substances build up in the blood and you lose your ability to control levels of ions and water in body which results in death.

40
Q

How can fertility be increased?

A
  • hormones FSH and LH can be given to a woman as a fertility drug to stimulate ovulation
  • IVF treatment
41
Q

How do dialysis machines work?

A

Keeps the concentrations of dissolved substances in the blood at normal levels and removes waste substances.

Persons blood will flow between partially permeable membranes surrounded by dialysis fluid. The membranes are permeable to ions and waste substances but not big molecules.

42
Q

What happens during the menstrual cycle?

A

Day 1- menstruation starts. Uterus lining breaks down.

Day 2-uterus lining builds back up again into a thick spongy layer full of blood vessels, ready to receive a fertilised egg.

Day 3-an egg develops and is released from the ovary at day 14- ovulation.

Day 4-the uterus wall is maintained. If no fertilised egg has landed, the sponge lining starts to break down and the cycle starts again

43
Q

How can fertility be controlled? +advantages & disadvantages?

A
  • the contraceptive pill- can’t be taken with other medications, people forget when to take it, doesn’t protect against STDs
  • implant-lasts for 3 years, doesn’t protect against STDs, can be painful
  • condom- protects against STDs, don’t always work
44
Q

What happens when a shoot tip is exposed to light?

A

More auxin accumulated on the side that’s in the shade than the side that’s in the light.
This makes cells elongate faster on the shaded side so the shoot bends towards the light

45
Q

Examples of plant hormones?

A
  • auxin is a plant growth hormone that controls growth near tips of shoots and roots
  • gibberellin stimulates seed germination, stem growth and flowering
  • ethene influences the growth of the plant by controlling cell division and causes fruit to ripen
46
Q

How does IVF work?

A
  • collect eggs from woman’s ovaries and fertilising them in a lab using mans sperm
  • fertilised eggs are grown into embryos in a laboratory incubator
  • once the embryos are tiny balls of cells, one or two of them are transferred to woman’s uterus
  • FSH and LH are given to stimulate eggs to mature before egg collection
47
Q

What is an auxin?

A

A plant hormone that controls growth near the tips of shoots and roots. Controls the growth of a plant in response to light (phototropism) and gravity (geotropism)

48
Q

What is meiosis?

A

Meiosis is the type of cell division by which gametes, are produced. Meiosis involves a reduction in the amount of genetic material and non identical cells are formed. (Sexual reproduction)

49
Q

What are some of the main organs in the endocrine system?

A
  • hypothalamus
  • pituitary gland
  • thyroid
  • adrenal glands
  • ovaries/testes
  • pancreas
50
Q

What is homeostasis?

A

Where the body needs to maintain a stable internal environment so that natural processes and enzymes can function properly

51
Q

What happens when the light receptors in the eye detect very bright light?

A
  • reflex is triggered that makes the pupil smaller
  • the circular muscles in the iris contract and the radial muscles relax
  • this reduces amount of light that can enter the eye so retina isn’t damaged
52
Q

What is mitosis?

A

It produces two new cells that are identical to each other, and to the parent cell (asexual reproduction)

53
Q

What happens to the eye in dim light?

A
  • the circular muscles relax and radial muscles contract

- this makes pupil wider (dilate)

54
Q

What happens if blood glucose levels are too high?

A

If too high:

  • insulin secreted into blood
  • liver converts glucose into glycogen
  • levels will go down
55
Q

How is information about light entering the eye passed on to the brain?

A

Information is sent using impulses via the optic nerve

56
Q

What happens if the blood glucose levels are too low?

A
  • pancreas releases the hormone glucagon
  • causes cells in liver to turn glycogen back into glucose which is then released into the blood
  • blood sugar levels will then rise
57
Q

How does the body maintain water and nitrogen balance?

A
  • the kidneys control water concentration of blood plasma

- also control salt levels and excretion of urea

58
Q

How is urine produced?

A
  • small molecules (water, salt, glucose, urea) filtered out of blood
  • kidneys reabsorb all of glucose and as much salt and water body needs, putting them back in blood
  • some waste substances are now left (all urea) passes to the bladder and is excreted
59
Q

What is a stimulus?

A

A change in the external environment

60
Q

What would happen if a bee stung your finger?

A
  • bee stings finger
  • pain receptors stimulated
  • impulses travel along sensory neurone
  • impulses passed along relay neurone via synapse
  • impulses travel along motor neurone via a synapse
  • when impulses reach muscle, it contracts
61
Q

What is the role of a receptor?

A

It detects a stimulus

62
Q

What is the function of the retina?

A

Contains receptor cells sensitive to light intensity and colour

62
Q

What is the function of the optic nerve?

A

Carries impulses from the receptors on the retina to the brain

63
Q

What is the function of the sclera?

A

Tough supporting wall of the eye

64
Q

What is the function of the iris?

A

Muscles that allow it to control how much light enters the eye

65
Q

What is the function of the ciliary muscles?

A

Controls the shape of the lens along with the suspensory ligaments

66
Q

What is the main function of the nervous system?

A

Means humans can react to their surroundings and coordinate their behaviour

Biology Paper 2 (3 decks)

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