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Biology > B11: Homeostasis > Flashcards

B11: Homeostasis Flashcards

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1
Q

what is homeostasis?

A
  • regulation of internal conditions of a cell/organism to maintain optimum conditions for function in response to external/internal changes
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2
Q

what does homeostasis control?

A
  • blood glucose conc
  • body temp
  • water levels
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3
Q

important structures of endocrine system and function?

A

PITUITARY GLAND - hormones like FSH/LH
PANCREAS - produce insulin
THYROID - produce thyroxine
ADRENAL GLAND- andrenaline
OVARIES - oestrogen
TESTES - testosterone

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4
Q

what does the

pituitary gland do?

A
  • act on other glands to stimulate other hormones to be released
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5
Q

negative feedback of controlling blood glucose ?

A

1) blood glucose level RISES
2) pancreas released INSULIN
3) insulin stimuates muscle/liver cells to take up excess GLUCOSE from blood = blood glucose DECREASES

1) Blood glcuose FALLS
2) pancreas releases GLUCAGON
3) GLUCAGON stimulates LIVER CELLS to break down GLYCOGEN–> GLUCOSE = blood glucose rises

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6
Q

what is/treatment of

TYPE 1 DIABETES

A
  • pancreas fails to produce sufficient insulin to control blood glucose levels
    -TREATMENT: insulin injection
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7
Q

what is/treatment of

TYPE 2 DIABETES

A

cells of body become RESISTANT to insulin/insufficent insulin produced by pancreas
TREATMENT: - low carb diet
-regular excerise to reduce need for insulin

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8
Q

stages of menstrural cycle?

A
  1. MENSTRUATION (lining sheds)
  2. lining thickens
  3. OVULATION ( egg travels down oviduct into interus)
  4. lining is MAINTAINED to accept fertilised egg
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9
Q

interactions fo hormones in menstrural cycle?

A
  • Pituitarty gland produces FSH (stimulates maturation of egg in ovary) –> produces OESTROGEN
  • Oestrogen causes GROWTH/REPAIR of lining of uterus wall = inhibits FSH/stimulates pituitary to release LH (OVULATION)
  • Foliicle becomes a CORPUS LUTEUM/produces PROGESTERONE - maintain uertus lining
  • – if egg not fertilised- lining shed/progesterone drops- MENTSTRUATION
  • if fertilised, Progesterone produced , mainaining lining
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10
Q

chemical contraceptives examples , what does it contain , how does it work?

A

PILL : - oestrogen/progesterone
- high levels of oestrigen inhibit FSH (egg cant mature)
- progesterone inhibits LH (egg cant be released)/stimulates production of THICK MUCUS so sperm cant reach egg

INJECTION,IMPLANT,SKIN PATCH:
- progesterone
- inhibits FSH/LH
- reduced chance of forgetting to take pill

Intrauterine devices (IUD) -
- plastic IUD produce PROGESTERONE (thick mucus so sperm cant reach egg)
- copper IUD release of copper ions disabling SPERM CELLS

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11
Q

Examples of barrier contraceptives ?

A

condoms/diaphrams - prevent STIs
spermicidal agnets kill/disable sperm

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12
Q

what is natural contaception?

A

abstaining from inetrcourse when egg may be in oviduct

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13
Q

what is surgical contraception?

A

STERILISATION
- fallopian tubes cut/tied
- sperm ducts cut/tied in VASECTOMY

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14
Q

what is

negative feedback

A
  • helps maintain cnditions of body within a optimal , narrow range
  • involves detecting level of substance and triggers response to return to normal
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15
Q

what is importance of

thyroxine

A
  • stimulates Basal metabolic rate (BMR)
  • Stimulates protein synthesis for growth/development
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16
Q

what happens if throxine is too high or too low?

A

if too high - TSH is inhibited
if too low , TSH is released

17
Q

what is hyperthyroidism and hyporthyroidism?

A

Hyperthyroidism : thyroid overactive (too much thyroxine released, increasing BMR)
Hypothyroidism: underactive thyroid

18
Q

what IS GRAVITROPISM and what is a POSITIVE/NEGATIVE response?

A

growth towards/way from gravitaional pull
POSITIVE : growth towards gravity
NEGATIVE : growth away from gravity

19
Q

what is PHOTOTROPISM and what is POSITIVE /NEGATIVE response?

A

growth towards/away from light
POSITIVE : growth towards light
NEGATIVE : growth away from light

20
Q

what do auxins control amd what do they promote in the shoots/roots?

A

coordinate /control growth
SHOOTS : promote cell elongation
roots: INHIBIT cell elongation

21
Q

how does light/gravity effect distrubution of auxin?

A

in shoots, auxin distrubution is effected by LIGHT/GRAVITY
in roots it only affected by GRAVITY

22
Q

WHAT HAPPNES TO PLANT IF

placed on its side?

A

AUXINS accumilate on lower side , so upper side has LESS CONC of auxin.

SHOOTS: lower side grows faster , so grows upwards
ROOTS : lower side grows slower , so grows DOWNWARDS

23
Q

Uses of auxins, ethene, gibberellins ?

A

AUXINS - used as selective WEED KILLERS (disrupts growth of weeds/can effect other plants badly)
- PROMOTES GROWTH OF TISSUE CULTURE

ETHENE: - control ripening of fruit (inhibited to delay ripening in storage)

GIBBERELLINS: - end seed dormancy
- promote flowering
- increase fruit size

24
Q

REQUIRED PRACTICAL : plant growth method

A

1) set up petri dishes with cotton wool and equal volumes of water
2) put ten mustard seeds in each
3) put in warm place/allow to germinate (grow quicker in warm)
4) add more water if cotton gets dry
5) move dishes : one in light, partila light, darkness
6) measure height of each seedling, every day, for a week
7) record heights in tbale/take a mean

25
Q

what is a hormone ?

3mks

A
  • a chemical messenger
  • made by endocrine system
  • released in blood
26
Q

causes of infertility?

A
  • low levels/inssufficient reproductive hormones effecting development of sperm/egg cells
  • issues with female’s reproductive system
27
Q

what is the ‘fertility drug’ and the side effects?

A

giving FSH/LH to stimulate egg production

28
Q

when is IVF used?

A

when male and female have issues with fertility

29
Q

process of IVF?

A
  1. give mother FSH/LH to stimulate maturation of several eggs
  2. eggs collected by mother /fertilised by sperm in lab
  3. fertilised egg develops into embryo
  4. when embryo is tiny ball of cells, 1 or 2 embryos are implanted into woman’s uterus
30
Q

what advancements help increase success rate of IVF?

A

Improvements in microscope techniques / micro-tools that enable single cells to be remved from embryo for genetic testing
- to identify if embryo is healthy/has genetic faults that couple may want to consider

31
Q

issues with fertility treatments?

A
  • several eggs can be released at once leading to multiple births (fertility drug)
  • expensive
  • low success rate - emotionally upsetting
  • some with IVF will be pregnant late
  • ethical issues with IVF (of who owns embryos/ if they can be used in research before destroyed)
  • use of genetic testing can be misused (choose genes of baby)

Biology (20 decks)

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