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AQA GCSE Biology > Homeostasis and Response > Flashcards

Homeostasis and Response Flashcards

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1
Q

Homeostasis

A

The regulation of the internal conditions of a cell or organism in response to internal or external changes

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2
Q

Why is Homeostasis important? [2]

A
  1. Constant condition for Enzyme Action

2. And Cell Function

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3
Q

What 3 things does Homeostasis control?

A
  1. Blood glucose Concentration
  2. Body Temperature
  3. Water and Ion levels
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4
Q

When Glucose levels are high… [4]

A
  1. Glucose level RISES
  2. Pancreas releases INSULIN
  3. Glucose converted into GLYCOGEN (stored- liver or muscle cells)
  4. Glucose level FALLS and returns to NORMAL
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5
Q

When Glucose Levels are low… [5]

A
  1. Glucose levels are LOW
  2. Pancreas releases GLUCAGON
  3. Glucagon stimulates glycogen to be converted into glucose
  4. Glucose released into the blood
  5. Glucose level RISES and returns to NORMAL
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6
Q

When body temperature is too high… [3]

A
  1. blood vessels supplying the skin capillaries dilate
  2. more blood flows through the skin
    = Vasodilation
  3. more heat is lost
  4. sweat glands release more sweat to cool the body => by evaporation
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7
Q

When body temperature is too low… [3]

A
  1. blood vessels supplying skin capillaries constrict
  2. Reduces blood flow through the skin
    =Vasoconstriction
  3. less energy (heat) is lost to the surroundings
  4. ‘shivering’ bymusclecontraction
    release heat energy
    from respiration, some of which is lost as heat
  5. Sweat glands produce less sweat
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8
Q

What is the optimum body temperature for humans?

A

37 Degrees Celsius

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9
Q

Describe how reflex actions take place [6]

A
  1. Stimulus / heat detected bytemperature receptors in skin
  2. Impulses travel along sensory neurone to spinal cord
  3. Chemical transmission across synapse
  4. Via relay neurone
  5. Impulses to the motor neurone
  6. Muscle / effector contracts, moving the hand away
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10
Q

How do synapses pass on impulses? [3]

A
  1. When impulse reaches the end of a neurone a chemical is released.
  2. Chemical diffuses across the gap
  3. Converted back into electrical impulses
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11
Q

Cerebral Cortex

A

Consciousness, intelligence, memory and language

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12
Q

Cerebellum

A

Coordinating muscular activity and balance

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13
Q

Medulla

A

Unconscious activity-controlling breathing, heart beat

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14
Q

Hypothalamus

A

Maintains homeostasis- controls body temperature

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15
Q

Pituitary gland

A

Produces hormones which coordinate and control body systems

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16
Q

How can we map areas of the brain? [3]

A
  1. Studying patients with brain damage (Phineas Gage)
    =Explosive accident blew an iron rod through Gages skull. after accident polite and hardworking => wild, unreliable and rude
    =Modern scans show that the accident removed part of cerebral cortex
  2. Electrically stimulating parts of the brain (behavioural changes)
    =Stimulate different parts of the brain and see effect.
    =NO sensory nerve endings, brains surgery done on conscious patients
    => People experience hunger, anger, fear and thirst because relevant areas of brain are stimulated
  3. Using MRI scan
    =Tumor or stroke will affect a persons behaviour
    => MRI shows which areas are affected
    => Scientist can link loss of function (loss of speech or movement) to damages in particular region of the brain
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17
Q

Why is it difficult to investigate and treat brain disorder? [3]

A
  1. Very complex and delicate
  2. Drugs do not always reach the brain
  3. Surgery is difficult because it is not fully understood what each area of the brain actually does
  4. Range of different chemicals released in the synapse
  5. involves many neurones in different areas
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18
Q

Sclera

A

White outer layer of Eye- strong and tough (not easily damaged)

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19
Q

What are the functions and adaptations of the Cornea? [3]

A
  1. Transparent part of your eye=> allows light entry

2. Curved surface of cornea- => change the light rays coming into eye

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20
Q

Iris

A

Controls the size of pupil

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21
Q

Suspensory ligament and ciliary muscle

A

Change the shape of the lens=> fine focus light onto the retina

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22
Q

Retina

A

Light sensitive layers of cells

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23
Q

Optic Nerve

A

Carries impulses from the retina to the brain

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24
Q

Myopia

A

Short Sightedness

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25
Q

Hyperopia

A

Long Sightedness

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26
Q

What are the causes of Myopia? [2]

A
  1. Lens too curved/ long eyeball

2. => Light focuses in front of retina

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27
Q

What are the causes of Hyperopa? [2]

A
  1. Lens is too flat and thin/ short eyeball

2. => Light focuses behind retina

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28
Q

How can we treat Myopia? [2]

A
  1. Wear glasses with concave lens

2. => Spreads out light from distant objects (=> focuses light on retina)

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29
Q

How can we treat Hyperopia? [2]

A
  1. Wear glasses with convex lens

2. => brings light rays together more (=> focuses light on retina)

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30
Q

Hard contact lenses?[2]

A
  1. Last long time

2. Kept sterile to prevent infection

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31
Q

Soft contact lenses? [3]

A
  1. Made from flexible material => more comfortable
  2. Do not last as long
  3. Kept sterile to avoid infection
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32
Q

How can Laser Eye surgery treat Myopia? [2]

A
  1. Reduced thickness of Cornea

2. Refracts less light

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33
Q

How can Laser Eye surgery treat Hyperopia? [2]

A
  1. Change curve of Cornea

2. Effectively refracts light from close objects

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34
Q

When is Laser Eye Surgery to be used? [2]

A
  1. When eyes have stopped growing

2. When vision has become stable

35
Q

How can Replacement Lens solve vision issues? [2]

A
  1. Other lens added inside the eye

2. Corrects visual defect permanently

36
Q

What are the two techniques for Replacement Lens?

A
  1. Permanent lens are placed over natural lens

2. Faulty lens is replaced by an artificial lens

37
Q

What are the risks of Replacement Lens? [3]

A
  1. Damage retina
  2. Cataracts developing if natural lens remains in place
  3. Infections
38
Q

What is the endocrine system made up of?

A

Glands that secrete hormones directly into the bloodstream

39
Q

Hormones [3]

A
  1. Chemical Messengers
  2. Carried in the bloodstream
  3. To a target organ (cells) where an effect is produced
40
Q

What is the role of hormones from the pituitary gland? [4]

A
  1. Controls growth in children
  2. Stimulates thyroid gland to make thyroxine=> rate of metabolism
  3. Women: Stimulates ovaries to produce and release eggs, produce Oestrogen
  4. Men: Stimulates Ovaries to make sperm and testosterone
41
Q

What is the role of hormones from the thyroid? (Thyroxine) [3]

A
  1. Controls Metabolic Rate
  2. Controls growth and development in young animals
  3. Controlled by negative feedback
42
Q

What is the role of hormones from the pancreas? (Insulin)

A

Controls levels of glucose in blood

43
Q

What is the role/effect of hormones from the Adrenal? (Adrenaline) [3]

A
  1. Made due to fear/stress
    • Heart rate and breathing rate increases
      => Glycogen in liver is converted into glucose for respiration
      => Pupils of the eye dilate to let more light in
      => Mental awareness increases
      => Increase blood flow to muscles
      => Increase oxygen and glucose to muscle and brain
      => More energy is released
  3. “Flight or fight”
44
Q

What is type 1 diabetes?

A

When the pancreas fails to produce enough insulin

45
Q

What is the treatment of Type 1 Diabetes?

A

Regular insulin injections

46
Q

What is Type 2 Diabetes?

A

When cells are less responsive to insulin

47
Q

What is the treatment for type 2 diabetes? [2]

A
  1. Reduce carbohydrate (glucose) intake

2. Regular exercise (glucose used in respiration for energy)

48
Q

What happens when Thyroxine levels drop? [5]

A
  1. Thyroxine levels in the blood FALL
  2. Detected by the brain
  3. More TSH released from pituitary gland
  4. TSH stimulates production of thyroxine by the thyroid gland
  5. Thyroxine levels rise
49
Q

Explain the effect of an overactive thyroid on the body? [4]

A
  1. Too much thyroxine is released into the blood
  2. Metabolic rate is raised
  3. Increased formation of glycogen/ lipids/ proteins
  4. Increase in breakdown of excess proteins
50
Q

Urea

A

A poisonous nitrogenous waste

51
Q

What is the process of Urea? [3]

A
  1. Digestion of protein in food=> excess amino acids
  2. Converted to ammonia via deamination
    3, Toxic ammonia converted to urea=> safe excretion
52
Q

How does the kidney create Urine? [6]

A
  1. Kidney FILTERS the blood
  2. Glucose, mineral ions, urea and water move from the blood into the kidneys
  3. Blood cells and large protein are TOO BIG to leave the blood in the filtering process
  4. Urea is a toxic product it is released in urine
  5. All of the glucose is REABSORBED back into the blood by diffusion or active transport
  6. Amount of water and ions that are reabsorbed varies. This is called selective reabsorption
53
Q

What happens when water levels in the body are too low? [5]

A
  1. Water content too low in the BLOOD
  2. More ADH released from pituitary gland
  3. Into the blood
  4. Kidney reabsorbs more water
  5. More concentrated and small volume of urine produced
54
Q

What happens when water levels in the blood are too high? [5]

A
  1. If water content too high in the BLOOD
  2. Less ADH released from pituitary gland
  3. Into the blood
  4. Causing kidney to reabsorb less water
  5. More dilute and larger volume of urine produced
55
Q

What is dialysis?

A

The function of the kidney is carried out artificially

56
Q

How does Dialysis work? [6]

A
  1. Blood leaves the person mixes with blood thinners to prevent clotting
  2. Dialysis machine uses a partially permeable membrane which separates blood and dialysis fluid
  3. This allows small molecules to pass through the membrane
  4. Dialysis fluid has the SAME concentration of GLUCOSE as blood.. NO NET MOVEMENT OF glucose OUT of the blood (this stops water passing into blood by osmosis)
  5. Dialysis fluid- contains normal levels of ions as blood… ANY EXCESS IONS are removed by diffusion (mention high and low con)
  6. Dialysis fluid- Contains NO UREA- urea moves from a high concentration in the blood to low concentration in the dialysis fluid
57
Q

What are the advantages of Dialysis? [2]

A

Suitable for short term
no long term drug treatment
no rejection chance
Acts as an artificial kidney keeping a person alive

58
Q

What are the disadvantages of Dialysis?

A
  1. controlled diet- limit salt and protein intake between sessions
  2. expensive for NHS
  3. Regular dialysis sessions = attached to machine for several hours
59
Q

How does Kidney rejection work?

A
  1. Difference in antigen of donor kidney cells and of patients receiving transplant
  2. WBC quickly produce antibodies against kidney antigens
  3. Destroys the kidney
  4. = Organ rejection
60
Q

Advantages of Transplant? [3]

A
  1. prevent high blood pressure
  2. don’t need restricted diet / restricted fluid intake
  3. blood clots may result from dialysis
  4. Kidney works all the time and dialysis works short term
  5. A good tissue match is needed for the donor kidney to reduce rejection
  6. no build-up of toxins / keeps blood concentration constant
61
Q

Disadvantages of Transplant? [3]

A
  1. rejection / problem finding tissue match
  2. use of immuno-suppressant drugssusceptible to other infections
  3. dangers during operation (high initial cost)
  4. no (suitable) kidneys available for transplant / long waiting list
  5. Operation risky for weakness/ old age
62
Q

What is the function of FSH (follicle stimulating hormone)? [2]

A
  1. Causes eggs to mature

2. Stimulates oestrogen production in ovaries

63
Q

What is the function of Oestrogen? [3]

A
  1. Inhibits FSH release
  2. Lining of uterus starts to thicken
  3. Stimulates LH release
64
Q

What is the function of LH (luteinising hormone)?

A
  1. Egg released from ovaries = Ovulation
65
Q

What is the function of Progesterone? [2]

A
  1. Continues to thicken lining of the uterus

2. Inhibits FSH and LH release

66
Q

What is FSH secreted by?

A

Pituitary gland

67
Q

What Is LH secreted by?

A

Pituitary gland

68
Q

What is Progesterone secreted by?

A

Empty follicle in ovaries

69
Q

What is Oestrogen secreted by?

A

Ovaries

70
Q

Give examples of Hormonal methods of reducing fertility [2]

A
  1. Oral contraceptives, e.g. combined pill=> contain oestrogen and progesterone=> inhibits FSH production so no eggs are released
  2. Injection, implant or skin patch of slow release progesterone (months/ years)
71
Q

Give examples of Non Hormonal methods of reducing fertility [3]

A
  1. Barrier
  2. Intrauterine devices (prevent embryo implantation)
  3. Surgical serialisation
72
Q

What are two ways Doctors can help increase Fertility?

A
  1. Fertility drug (FSH and LH)=> stimulate egg growth

2. IVF treatment

73
Q

How does IVF treatment work? [6]

A
  1. Inject FSH and LH to stimulate the maturing and ovulation of the egg
  2. Collect several eggs and place in petri dish
  3. Fertilise with fathers sperm (outside of the body)
  4. keep in warm environment
  5. embryo produced
  6. several embryos implanted into the uterus => to increase the chance of being pregnant
74
Q

What are the disadvantages of IVF treatment? [3]

A
  1. Low success rate
  2. Multiple births=> premature/still births =risk to mother and baby
  3. Emotional and Physical stress
75
Q

Phototropism

A

Response to light

76
Q

How do plants respond to light? [4]

A
  1. Auxin found at the tip of the shoot or at root =unevenly distributed
  2. in shoots auxin triggers cell growth
  3. light causes auxin to concentrate on the darker side of the shoot = more auxin found in shaded area as auxin spreads down shoot
  4. cells on darker side grow faster than lighter side= bend towards light
  5. once light falls evenly on shoot auxin = evenly distributed = shoot grows straight again
77
Q

Gravitropism

A

Response to gravity

78
Q

Using Gibberellins [4]

A
  1. Speeds up germination
  2. Ends seed dormancy
  3. Promotes flowering throughout the year
  4. Increases size of fruit
79
Q

Using Ethene

A

Controls ripening of fruit

80
Q

Using Auxin [3]

A
  1. Weed Killers (Weeds grow rapidly and run out of food supply)
  2. Rooting powders (cuttings)
  3. Tissue Cultures
81
Q

Focusing Light [4]

A
  1. Light needs to be focused on the retina to see a clear image.
  2. If light is focused behind or in front of the retina- image = blurry.
  3. Light changes direction (refracts) as it passes through the cornea and the lens - focuses the light on the retina
  4. Image is formed upside down but the brain interprets image the right way up.
82
Q

why is it important to regulate blood sugar?

A
  1. Too much glucose in the blood would cause water to leave cells by osmosis.

= Too little and there would not be enough for respiration.

83
Q

advantages of IVF

A
  1. chance of having a baby
  2. mature egg can be stored until she wants to be pregnant
  3. stimulates and releases an egg
84
Q

reasons for infertility

A
  1. Lack of female hormones (FSH&LH)
  2. Damaged oviducts
  3. Lack of sperm in semen
  4. Obesity and eating disorders increases infertility
  5. Age

AQA GCSE Biology (7 decks)

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