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)