5.4 Hormonal communication Flashcards
define target cells
For non-steriod hormones cells that possess a specific receptor on their plasma membrane. The shape of the receptor is complementory to the shape of the hormone molecule many similar cells together from a target a tissue.
Define Endocrine system
a communication system using hormones as signalling molecules.
Define hormones
Molecules that are released by endocrine glands directly into the blood. they act as messenger carrying a signal from the endocrine gland to a specific target organ or tissue.
State how the endocrine system transports hormones.
Via the circulatory system.
Styate the different type of hormones and there differences
Protein -
they are not soluble in phospholipids and so are unable to enter the cell, and so they bind to cell surface receptors to create a second messenger (cAMP)
Steriod hormones, pass through phospholipids bilayer and have a direct effect on DNA.
State the role of an endocrine gland.
They release hormones directly into blood and known as ductless glands
Define adrenal cortext
the outer layer of the adrenal gland
define adrenal gland
one of a pair of glands lying above the kindeys, which release adrenaline and a number of other hormones known as corticoids such as aldosterone.
define adrenaline
A hormone relased from the adrenal glands, which stimulates the body for a fight or flight response.
Define adrenal medulla
inner layer of the adrenal glands
State the layers of tissue inside the adrenal gland.
capsule zona glomerulosa zona fasciculata zona reticularis medulla
Name three corticoid hormones released by the adrenal gland.
Mineralcorticoids (aldosterone)
Glucocorticoids
Cortisol
State the function of aldosterone
released from zona glomerulosa,
helps to control conc of Na+ and K+ in blood aswell as in kindeys as it increases absorption of Na+ and decrease for K+ in the distal tubules and collecting duct.
State the function of glucocorticoids
released from the Zona fasciculata,
controls the metabolism of carbohydrates, fats and proteins.
State the function of Cortisol
released from the zona reticularis,
if correct enzymes are not present then the precursor androgen, corisol converts sex hormones.
State the roles of adrenaline
- Relaxing smooth muscles in the bronchioles
- increasing stoke volume of the heart
- increase heart rate
- causing general vascostriction to raise blood pressure
- stimulating conversion of glycogen to glucose
- dialting pupils
- increase mental awaerness
- inhibiting the action of the gut.
- erect body hairs.
Define Beta cells
cells found in the islets of langerhans that secrete the hormones insulin.
Define glucagon
a hormone that causes an increase in blood glucose concentration
define insulin
the hormone, released from the pancreas that causes blood glucose levels to go down.
explain why the pancreas is a special organ
is has both a endocrine and exocrine function:
- pancreatic juices contains enzymes which is secrated into the small intensines through the duodenum.
- hormones which are secreted from the islets of langerhan into the blood.-
explain the role of the pancreas exocrine function
secretes substances into duct most cells synthesis and release digestive enzymes.
acini are groups of exocrine cells surrounding tiny tubules acinus plural
acini join to form intralobular ducts.
pancreatic duct carries fluid into the duodenum.
Fluid contains pancreatic amylase, typsinogen (deactivated trysin), lipase.
Explain the endocrine function of the pancrease
The islets of langerhan contains the Aplha cells and beta cells.
a - glucogon.
b - insulin.
State the effects of glucogon.
Glycogen is converted to glucose (glucogenolysis) by phosphorylase A, which is one of the zymes activated in the cascade.
more fatty acids are used in repiration
Amino acids and fats are converted into additional glucose, by gluconeogensis.
Describe how glucogon and insulin are an example of negative feedback
as insulin concentration increases, it decrease the concentration of glucose in blood, this will stimulate the production of glucogon by alpha cells in the pancreas.
the increase in glucogon will trigger cells to breakdown glycogen into glucose and releasing it into blood increase blood glucose conentration.
the increase in blood glucose conentration causes beta cells to synthesis insulin and is release increase its concentration. and so on.
