Hormones Flashcards
What are target cells?
Body cells with specific receptors for specific hormones.
What are endocrine glands?
Ductless, made up of cell groups and secrete hormones into capillaries.
Into blood.
What are exocrine glands?
Secrete juices into a duct.
What are the components of the adrenal glands?
Medulla (inner) secretes adrenaline and steroid hormones.
Cortex (outer) makes protein hormones - increase hr, glycogen to glucose, more blood to the brain and muscles.
What are steroid hormones?
Formed from lipids - can enter through cell membrane as soluble. Bind to receptors in cytoplasm. Complex enters nucleus and bind to receptors on chromatin.
eg. sex hormones
What are peptide hormones?
Made of amino acids. Not enter cells - bind to receptors on cell surface. Release molecules inside cells = second messengers.
Turn gene transcription on/off –> effect.
eg. adrenaline
What is a second messenger?
Signalling molecule in cell - stimulates change in cell activity.
How do peptide hormones carry out effects and change cell activity?
They are first messengers, so bind to and activate G-proteins in membrane. Effector molecule activated and can start cascade of enzyme-controlled reactions.
What is the function of the pancreas?
Forms and secreted digestive juices into duodenum of small intestine. Endo and exocrine gland.
What is ATP converted to by adenyl cyclase?
cAMP.
What are the small groups of exocrine cells in the pancreas?
Acini synthesise digestive enzymes to juices to tubule. Grouped into lobules around tubule.
Tubules join to form interlobular ducts –> pancreatic duct.
What are islets of Langerhans?
Groups of cells with alpha and beta cells. Synthesise and secrete into blood vessels.
What are exocrine functions of the pancreas?
Of acini secrete pancreatic juices through duct series to SI. Fluid contains:
- digestive enzymes - pancreatic amylase, trypsinogen, lipase.
- sodium hydrogen carbonate
What are endocrine functions of the pancreas?
Alpha cells secrete glucagon, Beta cells secrete insulin. Single group of cells = islet of Langerhans.
What happens when blood glucose conc increases?
Insulin decreases. Beta cells detect.
No blood glucose, B cells have neg. resting potential.
Glucose diffuses into B cells.
In cell, glucokinase attaches phosphate group.
Respiration - glucose to ATP - k+ channels close.
Membrane potential is less negative so Ca2+ channels open.
Ca2+ enters the cell and binds to vesicles with insulin.
Insulin released by exocytosis.
What is high and low blood glucose called?
Low = hypoglycaemia. (tired, decreased brain function, coma.)
High = hyperglycaemia (long term - organ damage.)
What happens when insulin binds to membrane?
Intracellular changes to decrease blood glucose.
What happens when there is a low glucose conc?
Vesicles of glucose transporter in cytoplasm.
When insulin binds, vesicles fuse with membrane + insert glucose transporters (more glucose into cells).
Insulin causes them to change shape - more glucose in by facilitated diffusion.
Insulin - more glucose used in respiration instead of fats/aa.
What is the function of glucagon?
In blood, to hepatocytes with specific receptors. Bind and stimulate G-protein in membrane to activate adenyl cyclase in cell. Converts ATP to cAMP.
What is the role of the liver?
Glycogenesis, glycogenolysis, gluconeogenesis.
Take in blood glucose and bind to form glycogen - stored in liver.
Liver has lots of glycogen stores for low blood conc.
Liver run out of glycogen, can use glycerol and aa bc of glucagon.
What is diabetes mellitus?
Concentration of glucose in blood is not controlled effectively.
Peaks higher and for longer as removed slowly.
What is Type 1 diabetes?
Insulin dependent - not make insulin.
Autoimmune against B cells - not respond to increasing blood glucose.
Hyper and hypoglycaemia.
What is Type 2 diabetes?
Insulin independent. Not make enough insulin - cells not respond bc receptors less sensitive.
Hyperglycaemia - damage of organs + circulation.
What are risk factors for T2?
Obesity, high sugar diet, not exercising.
What are ways to treat T1?
Insulin injections - monitor. Insulin pump therapy, islet cell transplant.
What are ways to treat T2?
Lifestyle changes, severe cases - insulin injections.
What are sources of insulin?
Used to be from pigs, now from GM bacteria. Genetically identical so low rejection, ethical.
Stem cells = permanent and can cure but very experimental.
