Endocrine System
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The Endocrine System An overview of hormonal control and revision of reproductive hormones
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Transcript of Endocrine System
The Endocrine System
An overview of hormonal control and revision of reproductive hormones
The Endocrine System
Endocrine glands Release hormones directly into the
bloodstream They lack ducts so are often called ductless
glands. Many endocrine glands have other functions
e.g. pancreas, ovaries and testes
endocrine cell
endocrine cell
endocrine cell
bloodstream
endocrine cell
bloodstream
target cell
endocrine cell
bloodstream
target cell
endocrine cell
bloodstream
target cell
endocrine cell
bloodstream
target cell
endocrine cell
bloodstream
target cell
pathway of chemical coordinator in endocrine system
The Endocrine System
Hormones are released as a result of the following: Direct nervous stimulation of the appropriate gland,
e.g. secretion of adrenaline from the adrenal medulla occurs following stimulation by the sympathetic nervous system
The presence of particular compounds in the blood, such as:
1. metabolites, e.g. release of insulin in response to glucose
2. other hormones secreted by anterior lobe of the pituitary gland
The Endocrine System
Negative feedback loops characterise the latter two methods of controlling endocrine secretions.
presence of metabolite or
pituitary hormone in blood
presence of metabolite or
pituitary hormone in blood
endocrine
gland
stimulation
presence of metabolite or
pituitary hormone in blood
endocrine
gland
stimulation
hormone
release
presence of metabolite or
pituitary hormone in blood
endocrine
gland
stimulation
hormone
release
hormone release
presence of metabolite or
pituitary hormone in blood
endocrine
gland
stimulation
hormone
release
hormone release
removal of metabolite
or inhibition of
pituitary hormone release
leads to
presence of metabolite or
pituitary hormone in blood
endocrine
gland
stimulation
hormone
release
hormone release
removal of metabolite
or inhibition of
pituitary hormone release
leads to
endocrine
gland
inhibition
presence of metabolite or
pituitary hormone in blood
endocrine
gland
stimulation
hormone
release
hormone release
removal of metabolite
or inhibition of
pituitary hormone release
leads to
endocrine
gland
inhibition
no hormone
released leads to
presence of metabolite or
pituitary hormone in blood
endocrine
gland
stimulation
hormone
release
hormone release
removal of metabolite
or inhibition of
pituitary hormone release
leads to
endocrine
gland
inhibition
no hormone
released leads to
leads to
The Endocrine System
Compounds are classed as hormones if they:• are released into the blood by a ductless gland• are carried by the bloodstream to a target organ• stimulate a change in the activity of the target
organ
Reproductive hormones
Female Follicle stimulating hormone, simulate the small
follicles in the ovary which contain the developing egg
Oestrogen, secreted by the developing egg, a mixture of hormones that promote secondary sexual characteristics and the uterine lining
Luteinising hormone stimulates the follicle to produce progesterone to maintain pregnancy after the release of the egg
Reproductive hormones
Male Luteinising hormone stimulates groups of
cells in the testes to produce androgens Testosterone the major androgen which
initiates and maintains secondary sexual characteristics in the male and stimulates sperm production
