Endocrine Physiology - Part 3 Flashcards
What is the name of the endocrine tissue in the pancreas?
Islets of Langerhans
What are the 4 cell types within the Islets of Langerhans? What do they produce?
a-cells: produce glucagon
b-cells: produce insulin
D-cells: produce somatostatin
PP-cells: produce pancreatic polypeptide
What is the half life of insulin?
5-8 mins
What is the effect of insulin on carb, fat and protein metabolism?
- stimulates glucose entry and increases glycogen storage in muscles and fat tissue
- increases glycogen production and storage in the liver
- decreases gluconeogenesis by the liver
- promotes fat synthesis
- promotes protein synthesis
What is the general effect of insuli?
- decrease plasma conc. of glucose
- increase cell stores of glycogen
- decreased plasma conc. of FFA
- increased cell stores of triglycerides
- decreased plasma conc. of AAs
What is the most powerful stimulator of insulin production?
rising blood glucose level above normal
What are some stimulators of insulin production?
- rise in blood AA and FA levels
- vagus stimulation
- someGI hormones
- hyperkalemia
Where is glucagon secreted?
by alpha cells of the pancreas
What is the effect of glucagon?
- catabolism of nutrients, especially between meals.
- results in an increase in blood glucose levels
- opposite of insulin
How is glucagon regulated?
- increased secretion from decreased blood glucose levels as in exercise, starvation, sympathetic activation, etc.,
How do bird glucagon levels differ from mammals??
birds have nearly twice as much glucagon - presumably due to higher energy requirements
What happens if there is too much glucose in plasma?
- glucosuria (in urine)
- polyuria (frequent urination) due to osmotic diuresis
- polydipsia (thirst) due to osmotic diuresis
- swelling of eye lense
- chronic bladder infections
- oxidative damage to capillaries
- poor circulation in eye
- cataracts
- ketoacidosis
How does the body regulate glucose homeostasis
- insulin after feeding
- glucagon in starved state
What is the effect of catecholamines on blood glucose level?
- increases blood glucose level
- helpful to combat stress situation in particular during physical activity
What is the effect of glucocorticoids on blood glucose levels?
- increase blood glucose level
- necessary for long term starvation and during stress
What is the effect of GH and Thyroid hormones on blood glucose levels?
- increase blood glucose level
- GH promotes fat and protein metabolism
What is diabetes millitus?
lack of insulin function or glucagon excess
What is diabete insipidus?
lack of ADH function
What are the symptoms of diabetes mellitus?
- hyperglycemia
- glycosuria
- polyuria
- polyphagia
What is Type I DM?
- total lack of insulin
- requires exogenous insulin for survival
- results from autoimmune destroying beta cells
- most common type in dogs
What is Type II DM?
- non-insulin dependent DM
- insulin secretion normal or increased but target cells don’t respond
- most common type in cats
Where are the parathyroid glands?
beside or within the thyroid gland
What is secreted by the parathyroid glands?
parathyroid hormone (PTH)
What is the action of PTH?
increase plasma Ca++ and lower (PO4)3-
What is the target tissue of PTH?
bone, kidneys and intestine
How is PTH regulated?
- low plasma Ca++ level triggers secretion
- parathyroid cells have Ca sensing receptors on their surface
What is the action of Calcitonin?
- produced by C cells of thyroid gland
- decrease plasma Ca++ level (weak affect)
What is the most important hormone in regulating Ca in fish
stanniocalcin
What animals may require vitamin D suplementation
heavily furred animals, animals at high latitudes, animals kept indoors, etc.
What is the function of Vitamin D?
enhances:
- intestinal absorption of Ca++ and (PO4)3-
- increased bone mineralisation
What disease can be caused by Vitamin D deficiency in animals?
rickets in prepubertal animals
osteomalacia in adults
What disease is caused by lack of Ca++ in lactating cows?
parturient paresis (milk fever)
What other organs have secondary endocrine functions?
- intestines
- kidneys
- heart
- gonads
What hormone is produced by the heart?
atrial natriuretic peptide (ANP)
What stimulus releases ANP?
increased BP, increased blood volume, increased blood Na+
What is the target tissue of ANP?
renal tubules mainly
What is the effect of ANP?
increases Na+ secretion mainly
What hormones are released from the kidneys?
- Erythropoietin
2. Renin-angiotensin-aldosterone system (RAAS)
