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Grade 12 IEB Life Science Strand 2 COMPLETE summary: Endocrine system, Reproduction, Strategies CA$12.34   Add to cart
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Grade 12 IEB Life Science Strand 2 COMPLETE summary: Endocrine system, Reproduction, Strategies

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  • Life Sciences
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  • 12th Grade

I know how overwhelming it is to stare at a thick pile of notes and not know where to start. Well, start here. I condensed all of strand 2 into just a few pages (without leaving out any important information). These notes helped me achieve 95% in Life Science for matric and I hope they'll help you ...

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  • February 12, 2024
  • 11
  • 2023/2024
  • Summary

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  • life science

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  • 12th Grade
  • Life Sciences
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endocrine system pancreas
Homeostasis Co-ordination
=maintainence of a constant internal env despite ∆s in the external env Endocrine+Nervous: operate tog to ensure integrated control to mantain homeostasis condition: diabetes mellitus 4. pancreas
what is internal env: immediate surroundings of living cells called tissue [stimulus-> receptor->control centre-> effector(muscle/gland)->response] =chronic disease characterised by high lvls of glucose in the b due to *endocrine(ductless)+exocrine(ducted)
fluid in multicellular orgs undersecretion/problem with insulin [- In SA about 6 mil sudder, 90% adults] 1. exocrine: secretion of pancreatic juice
flows along pancreatic duct into duodenum- helps with chem digestion
how is tissue fluid formed: part of blood(plasma) that leaks out of arterial Hormone 2. endocrine: secretion of hormones by I.L
capillaries due to filtration under pressure into spaces btw cells Type 1: insulin dpndt
a chemical messenger secreted by one endocrine gland or cell into the bloodstream and bcs p not make insulin- glucose remians in b
targeted towards cells in another organ stream instead of moving into cells location Islets of Langerhans(endocrine cells in p)
importance
hormones - alpha cells secrete glucagon
1. mantain internal env of orgs esp higher vertebrates in steady+balc state 1.released from endocrine glands directly into blood
- beta cells secrete insulin
2. establish optimum condition of orgs[conc of water, oxygen...] 2. travel in blood to target organs[affect certain cells, do not last long- broken down
target organ liver(both)+muscles(only insulin)
enzymes]
Feedback mechanisms 3. causes a response ie metabolic reaction
[Response is slower but longer lasting than nervous system] glucose
-> negative
4. hyperactive:Too much of the hormone being secreted -> hypersecretion - simple form of sugar(monosac)
-control mechanism whereby a ∆ from set point of any factor is corrected by
hypoactive: Too little of the hormone being->hyposecretion -soluble- transport in b
bring about a change in the oppdirection back to the normal - fuel for c.r., only enters cells if insulin present
e.g. TSH+thyroxin, insulin+glucagon, pit gland +ovaries, testes
exocrine- secretions carried in ducts where needed e.g. salivary glands, liver, pancreas
endocrine glands do not have ducts+secretions are carried in bloodstream to target org poor management: serious life-threatening implication glycogen
->positive -insoluble polysac
Endocrine glands: vascular, ductless glands that secrete hormones directly into the - short term: large quant dilute urine, extreme thirst, nausea, vomiting, coma
A deviation from norm continues in the same direction - long-term goals: prolong life+prevent complication e.g. blindness, kidney failure, -storage from of glucose in a
bloodstream to reach their target organs.]
ie.continues to get more/ less[not mantain homeostasis instead amplifies amputation of limbs+incr risk of heart attack+stroke
- found abundantly in liver+muscle
responses+processes, moving system further away from starting cond. ] -future cures on horizon- pancreas transplants
e.g. *Contractions during labour, Breast feeding function
control lvl of b glucose in blood[normal btw 3.5 and 5.5 mmol/l of b]
1. receptor: detects c∆ from set point-> control centre, processes Type 2: non-insulin dpnt[insulin resistant]
info+activates corrective mechanism -> effector responds+corrects change
insulin:lowers lvl of glucose in b
- by stimulating glucose to be absorbed from b by cells(esp muscle) makes c.m. more
permeable
.location,hormone,target organ, function , abnormality+symptoms
-be converted into storage form as glycogen in liver+muscles[also to fat- store under skin]

-glycagon raises lvl of glucose in b[ antagonistic effects- opposite]
- by stimulating glycogen stored in liver to break down into glucose
endocrine glands - glucose is released into b+incrs lvl[converts stored fat into glucose]

have other endocrine glands as target Insulin
Tropic hormones Chemical Co-ordination 1. after meal cont. carbs, glucose fm digested food is absorbed small intestine->into b
1. Thyroid stimulating(trophic) hormone[TSH/TTH] 1. hypothalamus 2. this will incr blood glucose lvls above normal set point
f: -stimulatea thyroid gland to secrete its hormone, thyroxin location: part of midbrain directly above the pituatary gland 3. b pass through pancreas, beta cells detect raised g lvls+respond- secreting insulin into b
2. Follicle stimulating hormone[FSH] 4. insulin goes to main target organs: liver+muscels where
hormones ADH (anti-diuretic hormone)+oxytocin
f: - in females: stimulates oogenesis in the ovary ie formation of eggs (ova) - makes cell. m more permeable to glucose which enables more g to leave b+enter cells
stored in posterior lobe of pituatary gland
-in males :stimulates spermatogenesis in testes ie sperm formation - incr rate at which glucose is converted into glycogen in the cells [g out of b- lvl lowered]
target organs ADH: targets kidney tubules+involved in conserving water in bd
3. Luteinizing hhormone [LH] 5. lower glucose lvl detected by insulin secreting cells -> stop releasing insulin into b
oxytocin: targets uterine muscles(contractions drg birth)
F: in females stimulates ovulation from ovary+formation of corpus luteum [receptro: pancreas, effector: liver+muscles]
mammary glands- breast feeding(let- down reflex)
4. Interstitial cell stimulating hormone[ICSH]
-in males stimulates testes to release testosterone a. ADH
function controls amt water absorbed back into b by kidneys ie Glucagon[exercise reduces]
helps conserve water. less secreted in urine(osmoregulation) -1.as b passes through pa, alpha cells detect low glucose lvls+respond s glucagon into b
3. thyroid gland abnormality undersecretion->Diabetes insipidus 2. -target cells: liver cells; glycogen ©s breakdown of stored glycogen into glucose
location:
2 lobes of butterfly- shaped gland found on either side of large amts of dilute urine released as less water reabsorbed into b - as result liver releases glucose into the b- incr b glucose lvl
trachea just below larynx in front of neck - incr lvl detected by glucagon secreting cells- then stop releasing glucagon into blood
lots of sweating-little water&lots of drinking lots of water- too much w in b-
hormones thyroxin [iodine is essential element- sea food, salt, iodised solute in b- need to conserve water need to excrete excess water
a goitre may develop if levels of iodine are low
Incr ADH: more water reabsrobed into b Decr ADH: less water reabsorbed into b- abnormalities:
target release of thryoxin from thyroid controlled by secretion of in kidneys(conc urine) more exreted in urine(dilute urine) high b glucose lvls=hyperclycaemia
organ TSH from pituatary gland into b that targets thyroid
function 1. incr basal metabolic rate- by controlling rate of c.r. b. Oxytoxin
2. promotes normal functioning of heart function(+ve feedback) stimulates uterus to contact during labour
3. promotes normal functioning of n.s.- sharpens stimulates milk release when baby suckles(let down reflex)
alertness+speed of reflexes
basal metabolic rate=amt energy body needs to keep functioning while at rest
2. Pituatary gland
Abnormalities •master gland -controls other glands
a. hypothyroidism[ too little t->low metabolic rate] •2 lobes- anterior(glandular- makes hormones), posterior (mainly neurons- store h)
treat: iodine supp/synthetic iodine location: attached to hypothalamus at base of brain by short stalk
- in adults: myxoedema hormones Growth hormone(GH?STH) Prolactin
-> decr metabolic rate, slow heart rate+low BP Tropic hormones: TSH, FSH, LH/ICSH, ACTH
-> mental+physical sluggishness,loss of mem, low bd temp- feels cold
1. Growth hormone /somatotrophic hormon [GH/STH]
2. -in children:cretinism f: promotes akeletal +muscular growth by stimulating synthesis of proteins
-child not grow physically, has immature sexual dvlp+stunted mental dvlp abnormality: ©tumour in PG- rare[prepubertal children
[once mental ab occ- not reversed] -> gigantism[oversecretion]
=when hypersecretion of GH results in overdvlp of skeleton (tall stature)
b. hyperthyroidism[too much t->high metabolic rate] -> pituatary dwarfism body prop normal, sexually immature[prep. children)
-> body temp is high+sweating incr hyposecretion of GH results in underdvlp of skeleton(short stature)
->heart +respiratory rate+bp incr - treat: injections of synthetic GH [STH] produced by gen engineered bacteria
->there are musclur tremors+nervousness -> acromegaly
-> sufferers often have a swollen thyroid gland=exophthalmic goitre = condition in adults where bones of face, hands+feet are enlarged due to oversecretion of
GH[leads to enlarged features+tongue due to thickn tissue]
Keeping thyroxin in blood constant[-ve feedback]
1. pituatary detects decr levl of thyroxin in b, so secretes more TSH 2. Prolactin
2. TSH stimulates thyroid to secrete more thyroxin returning its level to normal f: stimulates production of milk in female mammary glands as long as baby suckles(af birth)
3. higher lvl of thyroxin inhibits further secretion of TSH from pituatary responsible for maternal instinct
.˙. ensure lvl thyroxin in blood is kept at correct level at all times

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