B11: Homeostasis Flashcards
what is homeostasis?
- regulation of internal conditions of a cell/organism to maintain optimum conditions for function in response to external/internal changes
what does homeostasis control?
- blood glucose conc
- body temp
- water levels
important structures of endocrine system and function?
PITUITARY GLAND - hormones like FSH/LH
PANCREAS - produce insulin
THYROID - produce thyroxine
ADRENAL GLAND- andrenaline
OVARIES - oestrogen
TESTES - testosterone
what does the
pituitary gland do?
- act on other glands to stimulate other hormones to be released
negative feedback of controlling blood glucose ?
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
what is/treatment of
TYPE 1 DIABETES
- pancreas fails to produce sufficient insulin to control blood glucose levels
-TREATMENT: insulin injection
what is/treatment of
TYPE 2 DIABETES
cells of body become RESISTANT to insulin/insufficent insulin produced by pancreas
TREATMENT: - low carb diet
-regular excerise to reduce need for insulin
stages of menstrural cycle?
- MENSTRUATION (lining sheds)
- lining thickens
- OVULATION ( egg travels down oviduct into interus)
- lining is MAINTAINED to accept fertilised egg
interactions fo hormones in menstrural cycle?
- 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
chemical contraceptives examples , what does it contain , how does it work?
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
Examples of barrier contraceptives ?
condoms/diaphrams - prevent STIs
spermicidal agnets kill/disable sperm
what is natural contaception?
abstaining from inetrcourse when egg may be in oviduct
what is surgical contraception?
STERILISATION
- fallopian tubes cut/tied
- sperm ducts cut/tied in VASECTOMY
what is
negative feedback
- helps maintain cnditions of body within a optimal , narrow range
- involves detecting level of substance and triggers response to return to normal
what is importance of
thyroxine
- stimulates Basal metabolic rate (BMR)
- Stimulates protein synthesis for growth/development
what happens if throxine is too high or too low?
if too high - TSH is inhibited
if too low , TSH is released
what is hyperthyroidism and hyporthyroidism?
Hyperthyroidism : thyroid overactive (too much thyroxine released, increasing BMR)
Hypothyroidism: underactive thyroid
what IS GRAVITROPISM and what is a POSITIVE/NEGATIVE response?
growth towards/way from gravitaional pull
POSITIVE : growth towards gravity
NEGATIVE : growth away from gravity
what is PHOTOTROPISM and what is POSITIVE /NEGATIVE response?
growth towards/away from light
POSITIVE : growth towards light
NEGATIVE : growth away from light
what do auxins control amd what do they promote in the shoots/roots?
coordinate /control growth
SHOOTS : promote cell elongation
roots: INHIBIT cell elongation
how does light/gravity effect distrubution of auxin?
in shoots, auxin distrubution is effected by LIGHT/GRAVITY
in roots it only affected by GRAVITY
WHAT HAPPNES TO PLANT IF
placed on its side?
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
Uses of auxins, ethene, gibberellins ?
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
REQUIRED PRACTICAL : plant growth method
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
what is a hormone ?
3mks
- a chemical messenger
- made by endocrine system
- released in blood
causes of infertility?
- low levels/inssufficient reproductive hormones effecting development of sperm/egg cells
- issues with female’s reproductive system
what is the ‘fertility drug’ and the side effects?
giving FSH/LH to stimulate egg production
when is IVF used?
when male and female have issues with fertility
process of IVF?
- give mother FSH/LH to stimulate maturation of several eggs
- eggs collected by mother /fertilised by sperm in lab
- fertilised egg develops into embryo
- when embryo is tiny ball of cells, 1 or 2 embryos are implanted into woman’s uterus
what advancements help increase success rate of IVF?
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
issues with fertility treatments?
- 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)
