5.1.4 Hormonal communication Flashcards
What is Thermoregulation?
The control and maintenance of body temperature
What is Osmoregulation?
The control of water potential of bodily fluids
What are the 3 homeostatic mechanisms that are used to keep the conditions within the body near to constant?
- Thermoregulation
- Osmoregulation
- Control of blood glucose concentration
What is the endocrine system?
A chemical messenger system, where chemicals are secreted from glands into ducts or the bloodstream
What is a hormone?
A hormone is a chemical messenger produced by an endocrine gland and carried by the blood
What are the differences between Exocrine and Endocrine glands?
Endocrine Exocrine
- secretes into bloodstream -secretes into ducts
- has no ducts -has ducts
- releases hormones -releases saliva/enzymes/sweat
What are some key features of hormones
-They are small molecules that can either be polypeptide/proteins/amino-acid
derivatives OR steroid based hormones
-released from ductless exocrine glands straight into the blood plasma
-affect only target cells with the receptor for that specific hormone
-they have a short lifespan (hydrolised by enzymes or excreted via urine) to turn off
the effects quickly
how does a protein based hormone act on a cell?
It attaches to a receptor on the outside of the cell, releasing a second messenger on the inside
How does a steroid based hormone act on a target cell?
A steroid based hormone can pass through the plasma membrane and will attach to an intracellular receptor and make direct changes to the DNA
Give some examples of important protein based hormones and how the act on a cell
- Adrenaline
- Insulin
- Glucagon
These attach to receptors on the outside of a cell and cause a secondary messenger molecule to be released on the inside of a cell
Give some examples of steroid hormones and how they act on a cell
- Testosterone
- Oestrogen
Passes straight through plasma membrane and binds to an intracellular receptor, having an effect on the DNA in the nucleus
where are the Adrenal glands situated and what is their structure?
The adrenal glands are situated above the kidneys, they are separated into the cortex (outer) and medulla (inner)
releases adrenaline
what hormones are secreted by the Cortex of the Medulla of the Adrenal glands?
- GLUCOCORTICOIDS
- Cortisol: regulates glucose and protein metabolism as well as blood pressure
- Corticosterone: supresses inflammatory response
MINERALOCORTICOIDS
-Aldosterone: maintains salt conc to regulate blood pressure
ANDROGENS
-sex hormones with little effect
what hormones are released by the medulla of the adrenal glands
PROTEIN HORMONES (controlled by stress/fight or flight)
-Adrenaline: increases heart rate and blood glucose concentration
-noradrenaline: dilates pupils and allows vasoconstriction of blood vessels to non
essential organs
what are the 3 layers of the cortex of the Adrenal glands?
- Zona glomerulosa
- Zona Fasciculata
- Zona Reticularis
what is the Zona Glomerulosa?
- the outer layer of the cortex of the kidney. secretes mineralocorticoids
e. g aldosterone
What is the function of the Zona fasciculata?
Secretes glucocorticoids and is the middle layer of the cortex of the adrenal glands
What is the function of the Zona Reticularis?
It is the inner layer of the cortex of the adrenal glands and secretes cortisol and precursor molecules for sex hormones (androgens)
How does Adrenaline work on on the liver specifically?
Adrenaline in the bloodstream binds to a receptor on the target tissue, this will causes a secondary messenger to be produced (via the activation of adenyl cyclase with ATP) which is [cyclic AMP] which causes glycogenolysis in the liver converting glycogen to glucose
what are the effects of adrenaline on the Sino atrial node?
increased heart rate
what are the effects of adrenaline on ventricular cardiac muscle tissue
increased stroke volume
what are the effects of adrenaline on the muscles in the iris?
Dilates the pupils, the radial muscles contract and the circular muscles relax
what are the effects of adrenaline on the cerebrum of the brain
elevates mental awareness
what are the effects of adrenaline on the erector pili muscles of the skin
erects body hair (may scare predators/be more intimidating)
what are the effects of adrenaline on the smooth muscle on the gut wall?
inhibits peristalsis (the constriction of the intestines to move food along the gut)
what are the effects of adrenaline on the smooth muscle of arterioles
Means that less blood goes to the capillaries in the skin and gut and so it vasoconstricts
what is the histology (labelling parts of pancreas) of a pancreas under the microscope?
https://docs.google.com/document/d/1EQ2MKbjG-CcL6_XuwW4lnk8J4cHRp4GcVVxxBR_MvR4/edit?usp=sharing
try labelling this diagram ^^^^^^^^
answers to diagram:
https://docs.google.com/document/d/1ciPKV5ahjH8xf31HpQaPuVNnLPxOR-Cni2v6KKN9h5I/edit?usp=sharing
what is the function of the pancreas?
An organ just below the stomach that has both endocrine and exocrine glands which mostly secretes pancreatic juice containing enzymes AND has special cells that produce hormones Glucagon and Insulin
what are the islets of Langerhan?
these are areas of cells in the pancreas that contains both alpha and beta cells
a-cells produce Glucagon
b-cells produce insulin
what are the exocrine function of the pancreas?
-contains pancreatic juice filed with enzymes
-juice contains sodium hydrogen carbonate, making it alkaline and able to
neutralise stomach acid
-
what are the endocrine functions of the pancreas?
-α-cells produce and secrete glucagon, a hormone that raises blood glucose levels
via stimulating glycogenolysis and lipolysis
-β-cells produce insulin, a hormone that lowers blood glucose levels via stimulating glycogenesis
Insulin and glucagon are antagonistic to each-other as they both have opposite effects on the body
what happens if blood glucose levels go too high (hyperglycaemia)?
β-cells will detect the change in blood glucose levels and decrease the levels of glucagon being produced while increasing insulin levels, this inhibits glycogenolysis and gluconeogenesis and promotes glycogenesis and lipogenesis in tissues with insulin receptors e.g. the liver or skeletal muscle cells
how does insulin affect cells?
- increases permeability of cell plasma membranes to glucose via increasing the no of glucose channels
- increases aerobic respiration so more glucose is used and promotes glycogenesis and lipogenesis
what happens if blood glucose levels fall (Hypoglycaemia)?
α-cells detect change in blood glucose levels in blood and secrete glucagon. Main target cells like hepatocytes in the liver have the specific glucagon receptor, resulting in gluconeogenesis and glycogenolysis to happen releasing glucose into the blood
what are the effects of glucagon on the body?
causes glycogen to be converted into glucose via glycogenolysis, usually at the hepatocytes in the liver as they have glucagon receptors
also promotes the use of fatty acids in respiration
what are the 2 main types of hormones?
steroid hormones
peptide hormones
where in the adrenal gland is adrenaline produced?
adrenal medulla
How does adrenaline act on a target tissue?
- Adrenaline is released form the adrenal medulla into the bloodstream
- it binds to a complementary receptor on the outside of the target tissue, being the primary messenger
- this activates the enzyme adenyl cyclase, tht converts ATP into cyclic-AMP (cAMP), which is the secondary messenger
- cAMP starts a cascade of enzyme reactions within the cell
what is the structure of the adrenal gland
https://docs.google.com/document/d/1dIu7uRJXOVJy92lyX94EOUha6nME9_2be5sBSPCnEFY/edit?usp=sharing
