IEB life sciences human & plant reproduction, endocrine system and reproductive strategies summary for grade 11 and 12
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Course
Life Sciences
Institution
12th Grade
Book
Life Sciences
Summary of Human & Plant Reproduction, Endocrine system and Reproductive Strategies based directly off the IEB SAGS as well as the Answer Series Life Sciences book. This summary contains hand drawn images on various structures to make the learning more visual as well as containing information that ...
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1 By T.Dimitriu
Endocrine system (as per SAGS)
Hormone Secreted by Function
TSH Anterior lobe of pituitary gland Stimulates thyroid to secrete thyroxin
STH Anterior lobe of pituitary gland Promotes growth of skeleton and muscles by stimulating
protein synthesis
FSH Anterior lobe of pituitary gland Females: Stimulates the development of a primary
follicle to graafian follicle
Males: activates germinal epithelium that produces
sperm in testes
LH Anterior lobe of pituitary gland Females: Stimulates ovulation and development of
corpus luteum
Males: Stimulates cells of Leydig to produce testosterone
Prolactin Anterior lobe of pituitary gland Stimulates mammary glands to produce milk after birth
ADH Produced by hypothalamus, Controls reabsorption of water by making walls of renal
secreted by posterior lobe of tubules and collecting ducts more permeable to water
pituitary (more water reabsorbed). Conserves water
Oxytocin Produced by hypothalamus, Stimulates contractions of the Uterus which stimulates
secreted by posterior lobe of release of more oxytocin
pituitary
Thyroxine Thyroid gland Increase basal metabolic rate
Increase breathing & heart rate
Essential for normal growth
Essential for normal functioning of nervous system
Insulin Beta cells in pancreas Secreted when glucose levels rise above normal and
decreases glucose levels
Glucagon Alpha cells in pancreas Secreted when glucose levels drop below normal and
increases glucose levels
Aldosterone Adrenal cortex in adrenal gland Regulates ionic balance of tissue fluid
Adrenaline Adrenal medulla in adrenal gland Fight or flight hormone
Accelerates heart rate (more blood & oxygen transported
to muscles)
Increase blood pressure
Accelerates conversion of glycogen to glucose
, 2 By T.Dimitriu
Increase rate and depth of breathing
Increase muscle tone
Dilates pupil
Increases sweat production
Testosterone Testes Responsible for secondary sexual characteristics
Plays a role in development of sex organs
Maturation of sperm and improves quality of sperm
Oestrogen Developing graafian follicle in Responsible for secondary sexual characteristics
ovaries Plays a role in development of female sex organs
Inhibits release of FSH
Stimulates release of LH
Thickens endometrium
Progesterone Corpus luteum (placenta) Responsible for thickening of endometrium and
maintaining pregnancy
Inhibits release of FSH and LH
Diseases
➔ Under-secretition of STH: dwarfism
➔ Over secretition of STH: children→ gigantism; adults → acromegaly
➔ Shortage of iodine: simple goitre
➔ Over secretion of thyroxine: hyperthyroidism
➔ Under secretition: children → cretinism ; adults → myxoedema
➔ High glucose levels (insulin absent): hyperglycemia (diabetes)
Negative feedback
➔ change occurs in the normal levels
➔ change detected by receptors
➔ receptors transmit information by hormones/nerve impulses to effectors
➔ effectors respond & correct deviation
➔ return to normal detected by receptors & corrective action switched off
Homeostasis: maintenance of a constant internal environment in the body
Endocrine glands: ductless glands that release hormones into bloodstream
Exocrine glands: release secretions via ducts to a body cavity or the outside
Other information as per SAGS: debate current uses of hormones
, 3 By T.Dimitriu
Human Reproduction (as per SAGS)
Functions of human reproductive parts
Testes
➔ Produce and release sperm
➔ Produce testosterone
Epididymis
➔ Stores sperm until mature
➔ Mucous membrane along with peristaltic movement facilitates movement of
sperm
Vas deferens
➔ Transports sperm from epididymis to urethra by peristaltic movement
Seminal vesicle
➔ Secretion of mucous membrane provides sperm with fructose (source of food)
➔ Semen: seminal fluid & sperm
Prostate gland
➔ Secretes prostate fluid which ensures maximum motility of sperm and protects
sperm from low pH of vagina and urethra
Cowper’s gland
➔ Sectritions add to greater motility of sperm
➔ Lubricates the head of the penis
➔ Clears urethra of urine residue
Penis
➔ Inserted into the vagina to pass sperm into vagina
➔ Erection: Erectile tissue become blood filled due to increase blood pressure
➔ Ejaculation: Ejection of semen from penis
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