comprehensive notes for F214 hormones unit

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  • Created on: 20-12-12 12:21
Preview of comprehensive notes for F214 hormones unit

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Hormones
Hormones are signalling molecules that travel
long distances in the blood. They are secreted
by endocrine (ductless) glands. The adrenal
gland is an example.
Hormones have a unique function (doesn't
affect other cells). They have a specific
complimentary shape to the receptors in the
plasma membrane of cells in the target tissue.
Endocrine gland ­ it is a ductless gland that secretes hormones straight into the blood
Exocrine gland ­ it is a gland that secretes molecules into a duct where they are carried to where
they are needed.
An adrenal gland is composed of an outer adrenal cortex that surrounds an inner adrenal medulla.
The hormones from the adrenal cortex are steroids. Adrenaline and noradrenaline secreted by the
adrenal medulla are catecholamines which are made from amino acids. Adrenal medulla is found in
the centre of the adrenal gland and its cells manufacture adrenaline in response to stress.

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Region of the adrenal Hormones secreted Target organs Functions of
gland hormones
Adrenal cortex Mineralcorticoid; Kindey, gut Stimulates increase in
aldosterone absorption of sodium
ions leading to an
increase in blood
pressure
Glucocorticoids; Liver Stimulate increase in
cortisol and blood glucose
corticosterone concentration by
gluconerogenesis
Adrenal Medulla Catecholamines; Liver Examples: stimulate
adrenaline breakdown of
glycogen and increase
blood glucose
Noradrenaline Heart concentration
Increase heart rate
Adrenaline
Adrenaline has numerous effects on the body.…read more

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Adrenaline, noradrenaline 160-190 seconds
Antidiuretic hormone (ADH) 10-30 minutes
Insulin 5 minutes
Glucagon 5-10 minutes
Anabolic steroids Between 30 minutes and 16 hours.
First and second messengers.
Adrenaline as it is derived from amino acids, like insulin and glucagon, cannot cross cell membranes,
whereas lipid soluble steroid hormones such as testosterone, 17 oestradiol and progesterone can.
These steroid hormones interact with receptors inside the cytoplasm or nucleus.
Cells in target tissues for adrenaline have specific adrenergic receptors on their cell surface
membranes.…read more

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Pancreas
The exocrine function is the manufacture and secretion of pancreatic fluids which contain digestive
enzymes such as lipase, amylase and trypsin and alkaline sodium hydrogen carbonate. Small groups
of cells called acini (1x acinus) surround tiny tubules, in which they synthesise and secrete the
pancreatic fluids into. The tubules join up to form a pancreatic duct which carries the fluid into the
duodenum.…read more

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Pancreas is an organ has both endocrine and
exocrine functions which include:
Secretion of enzyme by the exocrine gland
by:
Pancreatic cell are distributed in to small
groups surrounded by tiny tubules
The cells secrete digestive enzymes into the
tubules
The tubules join the pancreatic duct
Which carries fluid into the beginning of the
small intestine containing enzymes
produced by acinar cells:
o Amylase
o Trypsin
o Lipase
Endocrine function Secretion of hormones takes place in
the islets of Langerhans.…read more

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As a meal is absorbed into the blood stream the concentration of glucose may increase by 50%. The
following events occur when the blood glucose concentration rises above the set point:
(1) The increasing concentration of glucose acts as a stimulus that is detected by cells in the islets
of Langerhans, which release insulin in response. (Insulin has a paracrine effect on cells, stopping
them from releasing glucagon so that glucose is not released into the blood by liver cells).…read more

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After a meal has been absorbed completely and also during exercise the blood glucose
concentration may decrease below the set point. The following events then occur
(1) cells stop releasing insulin. This means that cells take up less glucose.
(2) cells in the islets of Langerhans respond to decreasing concentrations of glucose by
releasing glucagon (glucagon has a paracrine effect on cells, stimulating them to make insulin
so they can release is when the glucose concentration increases).…read more

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Blood concentration too low:
cells detects change
secretes glucagon hormone
glucagon travels to target cells (hepatocytes)
cause conversion of glycogen to glucose, respiration of fatty acids and conversion of
amino acids to glucose…read more

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The regulation of insulin
(1) In the normal range of blood glucose concentration:
a. Membrane potential is at 70mV ATPpotassium ion channel proteins are open and
some potassium ions diffuse out of the cell
b. Voltage gated calcium channels are shut, the membrane is impermeable to calcium
ions.
(2) Blood glucose concentration rises as molecules form a meal are absorbed, glucose
diffuses into the cell through specific channel proteins (GLUT2).…read more

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Less glucose diffuses into the cell when the glucose concentration falls below the set point. Less
respiration occurs and the decrease in ATP concentration causes the ATPgated potassium ion
channel proteins to open.
Glucose is transported in solution in the plasma. There is not much glucose in the bloor or in cells at
any one time ­ as soon as it enters cells it is converted to glucose phosphate. This ensures a steep
concentration gradient for glucose.…read more

Comments

Izzy Mason

Thanks really useful :)

Swallowtail

This excellent set of notes include detailed information, flow diagrams and clear annotated diagrams outlining hormone action, first and second messengers, the regulation of glucose levels, the function of adrenaline and control of heart rate. The clear images will aid memory of the key factual information. Although designed with the OCR A2  specification in mind, they could be useful to any student needing to study these topics.  

Nimra

can you make some more notes on all topics for a2 level ocr?

goldner1

this really helped me find my center THANKS :)

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