Hormonal Communication Flashcards
what are endocrine glands
group of chemicals that secrete hormones into the bloodstream
what are the main endocrine glands
Pituitary
- growth hormone and ADH
Thyroid
- thyroxine and metabolism
Adrenal
- adrenaline
Pineal
- melatonin
Thymus
- matures white blood cells
Pancreas
- blood glucose
what are hormones
- chemical messengers
- secreted directly into the blood when a gland is stimulated
- bind to target cells and hormones stimulate the cells to produce a response
- first messenger - hormone that binds to the receptor
- second messenger - causes the effect inside the cell
what are the aspects of hormonal communication
- communication by hormones
- transmission in the blood
- slow transmission but wide response
- effect may be permanent and irreversible
what is the adrenal cortex
- outer region of the gland
- produces cortisol (stress hormone)
- produces aldosterone (regulate salts)
Glucocorticoids - regulates metabolism by how the body converts fats, proteins and carbohydrates to energy
Mineralocorticoids - control blood pressure , maintain balance between salt and water concentrations
what is the adrenal medulla
- inner region of the gland
- produce non-essential hormones
Adrenaline - increase heart rate, send blood quickly to muscles and brain, raise blood glucose
Noradrenaline - increases heart rate, widens pupils, high blood pressure
how is a pancreas a exocrine gland
- produces enzymes and release them via a duct into the duodenum
- produce pancreatic juice, amylase, protease, lipase
how is the pancreas an endocrine gland
- produces hormones and release them into the blood
what are the islet of Langerhans
- alpha cells - produce and secrete glucagon
- beta cells - produce and secrete insulin
what is the histology of the islet of Langerhans
- lightly stained
- large spherical clusters
how can blood glucose concentration be increased
Diet - carbohydrate rich foods
Glycogenolysis - glycogen is broken down into glucose which is released in the bloodstream and then reabsorbed
how can blood glucose concentration be decreased
Glycogenesis - production of glycogen, excess glucose is stored as glycogen
Respiration - glucose used by cells to release energy
what is the role of insulin
- if blood glucose concentration is high beta cells detect this and secrete insulin
How does insulin lower blood glucose concentration
- increasing rate of absorption of glucose by a cell
- increase respiratory rate of cells
- increase rate of glycogenesis
- inhibit the release of glucagon by alpha cells
what is the mechanism of insulin secretion
- at normal blood glucose concentration K+ channels in beta cells membrane opens and ions diffuse out of the cell
- when blood glucose rises glucose enters the cell by glucose transporters
- glucose metabolised inside mitochondria and produces ATP
- ATP binds to K+ channels closing them and depolarising them
- voltage gated calcium channels open
- calcium ions enter causing vesicles to release insulin by exocytosis
what is the role of glucagon
if blood concentration is too low alpha cells secrete glucagon into the bloodstream
how does glucagon raise blood glucose concentration
- glycogenolysis - liver breaks down glucagon back to glucose
- reducing the amount of glucose absorbed by liver cells
what is type 1 diabetes
- cannot produce insulin
- beta cells don’t work
what is type 2 diabetes
- cannot use insulin and control blood sugar levels
- beta cells don’t produce insulin/ body doesn’t respond to insulin
how do you treat type 1 diabetes
- regularly testing blood glucose - work out the dose of insulin needed
- injecting too much insulin can cause hypoglycaemia (low blood glucose)
- injecting too little insulin can cause hyperglycaemia (high blood glucose)
how do you treat type 2 diabetes
- lifestyle changes
- regulate carbohydrate intake
- match diet to exercise
- drugs to stimulate insulin production
how is medically produces insulin beneficial
- human insulin produced in a pure form so less likely to cause an allergic reaction
- insulin produced in large quantities
- cheap production costs
- no religious and ethical objections
what is the potential use of stem cells in the treatment of diabetes
- could be grown into beta cells
- beta cells implanted into pancreas
- person could make insulin
what is the fight or flight process
- threat detected by autonomic nervous system
- hypothalamus communicates with the sympathetic system (neurones) and adrenal-corticol system (hormones in blood)
- sympathetic system sends impulse to glands and smooth muscles for adrenal medulla to release noradrenaline and adrenaline into the bloodstream
- hypothalamus stimulates pituitary gland to release ACTH
- travels in bloodstream to the adrenal cortex to release hormones
what are the physical responses of fight or flight
- increased heart rate - pump more oxygenated blood
- blood glucose rises - increase respiration to provide energy
how does adrenaline serve as a 2nd messenger model
- adrenaline binds to its receptor adenylyl cyclase is activated
- adenylyl cyclase triggers conversion of ATP into CAMP
- increase in CAMP levels activate protein kinases which phosphorylase other enzymes
- triggers conversion of glycogen into glucose
how is heart rate controlled
- medulla oblongata controls heart rate and has 2 centres linked to the SAN
- increases heart rate by sending impulses through the sympathetic system along the accelerator nerve
- decreases heart rate by sending impulses through the parasympathetic system along to vagus nerve
