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What type of glands are ductless: endocrine or exocrine?
What are the three types of endocrine glands?
- Primary purpose endocrine glands e.g. pituitary, thyroid, parathyroid, pineal, adrenal
- Endocrine combined with other functions e.g. pancreas, testis, ovary, placenta
- Serve a secondary endocrine function eg kidney, liver, thymus, heart, GI tract, fat
Give examples of the following types of hormones a) proteins b) peptide c) amines d) steroids
- a) GH, ACTH, insulin
- b) oxytocin, vasopressin
- c) dopamine, melatonin, adrenaline
- d) oestradiol, cortisol, aldosterone
What are the three ways hormone release is regulated?
Hormonal, neural and humoral
What can affect the effectiveness of steroid and thyroid hormones?
Binding proteins - these hormones must be free to have an action
What type of hormone is GH?
Where is GH produced and released from?
The pituitary gland
What is the target are for GH?
It targets all areas of the body
How does GH promote the growth of tissues?
It increases cell size, promotes mitosis and differentiation of certain cell types
How does GH promote growth of the skeleton?
- Increased protein deposition by chondrocytic and osteogenic cells
- Increased reproduction of these cells
- Conversion of chondrocytes to osteogenic cells
- Stimulation of osteoblasts
What other metabolic effects does GH have?
- Increased protein synthesis
- Increased metabolism of fatty acids
- Decrease rate of glucose utilisation 'insulin resistance'
True or false: the pancreas has both endocrine and exocrine functions?
What are the endocrine areas of the pancreas called?
Islets of Langerhans
What type of cells produce a) insulin b) glucagon?
- a) beta cells
- b) alpha cells
What is the action of a) insulin b) glucagon?
- a) lowers blood glucose
- b) raises blood glucose
What stimulates insulin secretion?
Hyperglycaemia (high blood glucose)
What effects does the a) ANS b) parasympathetic NS have on insulin release?
What other factors a) increase b) decrease insulin release?
- a) Amino acids, fatty acids, GH, glucagon and certain gastrointestinal hormones
- b) somatostatin
What stimulates glucagon secretion?
Hypoglycaemia (low blood glucose)
What other factors a) increase b) decrease glucagon release?
- a) Amino acids and exercise
- b) Somatostatin
The body regulates energy stores at the level of the ...?
What are the two areas of the hypothalamus involved in energy storage regulation?
Appetite centre and satiety centre
What type of tissue secretes leptin?
Describe what happens to animals that are unable to secrete leptin
- They become obese within weeks of birth
- Have a low BMR and body temperature
- Are physically inactive
True or false: treatment with exogenous leptin can correct all the abnormalities in a leptin deficient animal?
What type of hormone is ghrelin?
What are the two major actions of ghrelin?
- Regulation of energy balance
- Stimulation of GH secretion
How does ghrelin regulate energy balance?
Stimulates hunger, suppresses fat utilisation in adipose tissue, stimulates gastric emptying and has positive effects on CV function
When are concentrations of ghrelin a) lowest b) highest?
- a) after a meal
- b) in the fasting just prior to the next meal
What a) suppresses b) augments ghrelin release?
- a) Feeding, hyperglycaemia, oxyntomodulin and obesity
- b) Fasting, hypoglycaemia and low leptin
What is PYY 3-36?
When is PYY released from the GI tract?
After a meal
When would PYY be released the most, after eating a) fats b) carbohydrates c) proteins?
a) fats - the higher the calorie content the more PYY is released
What are the local actions of PYY?
Inhibits gastric acid production, exocrine secretions from the pancreas, GI secretions and GI motility
What are the central actions of PYY?
It crosses the BBB, inhibits food intake and ultimately weight gain via the hypothalamus