Homonal communication - 5.4 Flashcards
What is the endocrine system?
A communication system using hormones as signalling molecules.
What are hormones?
Molecules that are either proteins or steroids which are released by endocrine glands into the blood. They act as messengers, carrying a signal from the gland to the target organ/tissue.
What examples of non-steroid hormones (protein/peptide)
Adrenaline, insulin, glucagon, thyroxine, insulin
Name three examples of a steroid hormone
oestrogen, testosterone, aldosterone, cortisol
What are endocrine glands?
Glands which secrete hormones into the blood
What are exocrine glands?
Glands which secrete their products into a duct
Name three examples of endocrine glands
Pituitary, adrenal, pancreas, (thyroid, ovaries, testes)
Name 3 examples of exocrine glands.
Salivary, liver, pancreas, (stomach)
What is a target cell of a hormone?
A cell in which the hormone causes an effect.
What do target cells of non-steroid hormones need to accept the signal?
Complementary receptors on their cell surface membrane.
What is a first messenger?
A non-steroid hormone.
What is a second messenger?
A signalling molecule released by the first messenger that stimulates a change in a cell.
Name an example of a second messenger?
cAMP
What type of gland is the adrenal gland?
Endocrine
What are the two regions of the adrenal gland?
1) Adrenal Cortex
2) Adrenal Medulla
What are the three parts of the adrenal cortex?
1) Zona glomerulosa
2) Zona fasciculata
3) Zona Reticularis
What type of hormones does the zona glomerulosa secrete?
Mineralocorticoids
Name an example of a mineralocorticoid
Aldosterone
What is the function of mineralocorticoids?
They help control concentrations of sodium and potassium.
As a result they maintain blood pressure.
Aldosterone acts on the distal tubules and collecting ducts in the kidney to increase water retention.
What type of hormones does the zona fasciculata secrete?
Glucocorticoids
Name an example of a glucocorticoid
Cortisol
What is the function of glucocorticoids?
Help control metabolism of carbohydrates, fats and proteins in the liver.
Cortisol stimulates the production of glucose in the liver
What does the zona reticularis secrete?
Sex hormone precursors
What type of hormone is adrenaline?
Non-steroid
Why cant adrenalin enter a cell like a steroid hormone?
It is polar
What are the three target cells of adrenalin?
Smooth muscle, cardiac muscle, hepatocyte
Name 7 affects of adrenalin on the body
1) Increased tidal volume
2) increased stroke volume
3) increased heart rate
4) vasoconstriction
5) pupil dilation
6) piloerection
7) inhibition of digestion
Why is the adrenal cortex well supplied with blood?
To enable hormones to be efficiently transported into the blood stream
Where in the adrenal gland is adrenalin secreted from?
Adrenal medulla
What are the two different functions of the pancreas?
Exocrine
-Secrete digestive juices
Endocrine
-Secrete hormones to control blood sugar levels
What are acini? What is their function?
Cells in the pancreas which group together to secrete digestive juices.
The digestive juices
- aid intake of nutrients from the small intestine into the blood via specific enzymes
- neutralise the stomach acid that has entered the small intestine via sodium hydrogen carbonate
What enzymes are contained within the digestive juices secreted by the acini?
1) Pancreatic amylase
- a carbohydrase which digests amylose (long polysaccharide) to maltose (disaccharide)
2) Trypsinogen
- an inactive protease (break down proteins) which will be converted to the active form trypsin when it enters the upper small intestine
3) Lipase
- digests lipid molecules
Where does the endocrine and exocrine functions of the pancreas occur?
Endocrine
-Acini
Exocrine
-Islet of Langerhans (beta/alpha)
What is the function of the islet of Langerhans?
Alpha cells
- secrete glucagon
Beta cells
- Insulin
What does glucagon and insulin do?
Glucagon
-causes the release of glycogen into blood glucose
Insulin
-causes blood glucose to be sored as glycogen in the liver
