Hormones, homeostasis, and reproduction

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Where is insulin secreted from?
Pancreas beta cells
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What does insulin do?
Stimulates liver and muscle cells to absorb glucose and convert it to glycogen, which is stored in these cells. Other cells absorb glucose and use it in cell respiration instead of fat.
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Where is glucagon secreted from?
Pancreas alpha cells
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What does glucagon do?
Stimulates liver cells to break down glycogen into glucose and release into blood.
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What causes type 1 diabetes?
An auto immune disease which destroys beta cells in the pancreas, so the amount of insulin produced is insufficient
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What is the treatment for type 1 diabetes?
Insulin injections
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What causes type 2 diabetes?
Target cells insensitive to insulin, so insulin injections normally ineffective
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Type 2 diabetes risk factors
fatty/low fibre diets, obesity caused by over eating, lack of exercise, genetic factors
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What is the function of thyroxin?
Regulates metabolic rate -> higher metabolic rate causes an increase in growth, body temp, and protein synthesis
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What happens when the hypothalamus detects an increased temperature?
The thyroid gland secretes less thyroxin, so normal body temp is restored.
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What happens when less thyroxin is secreted?
Reduced metabolic rate, vasodilation of skin arterioles, reduced respiration in brown adipose tissue, all causing a reduced body temp
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What happens when more thyroxin is secreted?
Increased metabolic rate, vasoconstriction of skin arterioles, shivering, increased brown adipose tissue respiration, all causing an increase in body temp
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What is leptin?
Appetite inhibiting hormone, secreted by adipose tissue -> targets hypothalamus
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How is leptin related to genetic obesity?
A person with double recessive allele 'ob' secretes less leptin -> appetite is therefore less inhibited
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Why were leptin injections not developed as an obesity treatment?
Only works for those few whose obesity is caused by the ob gene, others tend to be insensitive to it, so extra leptin does not help. Common side effects: skin irritation and swelling
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What causes the secretion of melatonin?
Ganglion cells in the retina detect light/dark, sending impulses to the Suprachiasmatic nuclei (SCN) in the hypothalamus, which controls secretion from the pineal gland
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What causes jet lag?
SCN and pineal gland continue to set the circadian rhythm, based upon a set time zone, despite being in a different one
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What determines the sex of a foetus?
SRY gene (on Y chromosome) codes for testis determining factor (TDF), a gene regulation protein, which stimulates teh expression of genes for testis development
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What is the function of testosterone?
causes pre-natal development of male genitalia (penis, sperm duct, prostate gland) and (when production increases during puberty) stimulates growth of secondary sexual characteristics
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What is the function of Oestrogen?
Causes pre-natal development of female reproductive organs (oviduct, uterus, vagina) and (when production increases during puberty) secondary sexual characteristics
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What is the function of progesterone?
Supports pregnancy, prepares uterus during menstrual cycle for the implantation of an embryo
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What was Aristotle's 'seed and soil' theory of reproduction?
The male produces a seed, which forms an egg when mixed with menstrual blood
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What limited William Harvey's reproduction research?
Lack of effective microscopes, use of deer (embryos remain microscopic for an unusually long period
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Card 2

Front

What does insulin do?

Back

Stimulates liver and muscle cells to absorb glucose and convert it to glycogen, which is stored in these cells. Other cells absorb glucose and use it in cell respiration instead of fat.

Card 3

Front

Where is glucagon secreted from?

Back

Preview of the front of card 3

Card 4

Front

What does glucagon do?

Back

Preview of the front of card 4

Card 5

Front

What causes type 1 diabetes?

Back

Preview of the front of card 5
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