Hormonal Communication Flashcards
What is the endocrine system?
The glands and organs that make hormones and release them directly into the blood so they can travel to tissues and organ all over the body.
What are hormones? What is their role in the body?
Hormones are chemical substances that act like messengers molecules in the body- carry information from one part of the body to another.
-Are secreted directly into the blood when a gland is stimulated (change in conc of a substance e.g blood glucose)
-Once secreted, the hormones are transported to all over the body
-diffuse out of the blood and bind to specific receptors on the membrane/ cytoplasm for that hormone
-Once bound to their receptors hormones stimulate the target cell to produce a response.
What are the types of hormones?
The type of hormone determines the way it cause it’s effects on a target cell.
Steroid hormones:-
-lipid soluble
-pass through the lipid component of the cell membrane
- bind to steroid hormone receptors to form a hormone-receptor complex (receptors are in cytoplasm and nucleus)
- hormone-receptor complex formed acts as a transcription factor and inhibits the transcription of a specific gene.
E.g. Oestrogen
Non- steroid hormone:-
-hydrophilic so cannot pass through the cell membrane
-bind to specific receptors on the cell surface membrane of the target cell.
-triggers a cascade reaction mediated by chemicals called second messengers.
E.g. Adrenaline
Hormonal vs neuronal communication? 7 each
Hormonal System:-
- communication by hormones
- transmitted by the blood
- travel through the whole body but target organs only respond
- response is widespread
- transmission + response is slow
- response is long lasting
- may be permanent + irreversible
Nervous system:-
- communication by nerve impulses
- transmitted by neurones
- nerve impulses travel to specific parts of the body
- response is localised
- transmission + response is rapid
- response is short lived
- effect is temporary and reversible.
What is the structure of the adrenal gland?
Made of endocrine tissue:-
- adrenal cortex- the outer region of the glands, produces hormones such as cortisol and aldosterone.
- adrenal medulla- inner/ centre region of the gland, produces non essential hormones such as adrenaline.
What hormones are produces by the adrenal cortex? What is the function of the hormone?
Glucocorticoids: includes-
Cortisol:-
-helps regulate metabolism by controlling the conversion of fats, proteins and carbohydrates to energy.
-helps regulate blood pressure and cardiovascular function in response to stress.
Corticosterone:-
-works with cortisol to regulate immune response and suppress inflammatory reactions.
Release of these hormones is controlled by hypothalamus.
Mineralocorticoids: includes-
Aldosterone:-
-helps control blood pressure by maintaining the balance between salt and water in the blood and body fluids.
-release is mediated by signals triggered by the kidney.
Androgens: includes-
- small amounts of male and female sex hormones are released- relatively small impact compared to testosterone and oestrogen but still important, especially for menopause in women.
What hormones are released by the adrenal medulla?
Hormones from adrenal medulla are released when the sympathetic nervous system is stimulated.
- Adrenaline - increases the heart rate sending blood quickly to muscles + brain. Rapidly raises blood glucose levels, by converting glycogen to glucose in the liver.
- Noradrenaline- works with adrenaline in response to stress, produces effects such as increased heart rate, widened pupils, widening air passages in lungs, narrowing of blood vessels.
What is the two main functions of pancreas?
exocrine glad:- produces enzymes and released via a duct into the duodenum.
Endocrine gland:- produces hormones and secretes them into the bloodstream.
What is the role of the pancreas as a exocrine gland?
Most of the pancreas is made of exocrine tissue which produces digestive enzymes and alkaline fluid known as pancreatic juice.
Enzymes and pancreatic juice are secreted into ducts and to the pancreatic duct and then released into duodenum (top part of small intestine)
What enzyme do the exocrine glands produce?
Amylases- break down starch into simple sugars. E.g. Pancreatic amylase
Proteases- break down proteins to amino acids. E.g. trypsin
Lipases- break down lipids into fatty acids and glycerol. E..g. Pancreatic lipase
What is the role of the pancreas as an endocrine gland?
Pancreas produces insulin and glucagon- which control blood glucose concentration.
Within the endocrine tissues are the islets of langerhans.
What are the islets of langerhans? what are the two types?
Are islands of endocrine cells scattered throughout the pancreas that produce hormones that are secreted into the bloodstream.
a- alpha cells- produce and secrete glucagon
B- beta cells- produce and secrete insulin
Glucagon
Glucagon is a hormone released from a-cells in the pancreas in response to low glucose concentration in order to increase the concentration back to its optimum- it does this by activating enzymes which break down glycogen into glucose (glycogenesis), producing glucose from other molecules.
Glycogen
Glycogen is a multi-branched polysaccharide of glucose that serves as a form of energy storage in animals and fungi.
Glycogenolysis
Is the breakdown of glycogen to produce glucose molecules.
- glucagon triggers this process after it detects a decreased blood glucose concentration-it activates enzymes within that breakdown glycogen molecules into glucose