Hormonal Communication Flashcards
(17 cards)
Hormonal system vs nervous system
Hormonal: Nervous system:
- Communications via hormones (chemicals). - Via nerve impulses.
- Transmission through blood. - Through neurones
- Transmission = slow. - fast
- Target organs respond. - Nerve impulses travel to specific parts of the body.
- Widespread response. - Localised response
- Slow response. - Fast response.
- Long-lasting response. - Short-lasting response.
- Irreversible/permanent efffect. - Reversible and temporary.
What is a hormone?
A steroid/ protein based molecule made by an endocrine gland into the blood = chemical messenger that binds to specific receptors on target cells.
What do endocrine and exocrine glands secrete?
Exocrine glands-
- Secretions other than hormones (enzymes /mucus).
- Passed into duct.
Endocrine glands-
- Secrete hormones DIRECTLY into blood.
- Triggered by NS/ hormones
What produces thyroxine and what does it do?
Produced by thyroid gland -> involved in thermoregulation.
What produces adrenaline and what does it do?
Adrenal glands and it triggers fight or flight.
What produces pituitary gland and what does it do?
ADH and it regulates water balance.
What produces glucagon and insulin and what does it do?
Produced by pancreas and involved in blood glucose regulation.
Advantages of steroid hormone.
- Faster response at target cell than protein based.
-Lipid soluble so easily pass through cell. - Surface membrane and nuclear membrane to have direct effect on genes (protein hormones cannot as they are hydrophilic).
How steroid hormones work (lipid soluble)?
1- In cell, hormone binds to internal receptors in cytoplasm/nucleus.
2- Forming “hormone-receptor complex”.
3- Which acts as a transcription factor -switching genes on/off.
4- Have direct effect on DNA of cell.
5- So certain proteins are made or inhibited.
E.g. sex hormones (testosterone, oestrogen, progesterone).
How non-steroid hormones work?
1- Hormones arriving at cell - 1st messenger.
2- Attaches to specific protein receptors on cell surface membrane as they have complimentary shapes.
3- CANNOT enter cell.
4- It activates other molecules inside the cell -> G protein is activated.
5- It activates enzyme (usually adenyl cyclase).
6- Which catalyses the conversion of ATP to cAMP.
7- cAMP = 2nd messenger that brings about response of cell.
8- By acting on protein channels in memb OR by causing a “cascade” of enzyme controlled reactions.
What are the 2 types of adrenal glands and where are they located?
- Cortex and medulla -> both involved in stress response.
- Located on top of each kidney.
What part of the glands is adrenal cortex and what type of response does it cause?
- Outer region of glands.
- short and long term responses to stress.
- Controlled by hormones from pituitary gland in brain (which is controlled by hypothalamus).
What do adrenal cortex release?
1- Glucocorticoids (e.g. cortisol)
- Regulates metabolic rate and energy release from respiration.
- Stimulates release of glucose from glycogen stores for respiration.
- Regulates blood pressure - Suppresses immune system.
2- Mineralcorticoids (e.g. aldosterone)
- Regulates salt and water balance to control blood pressure.
3- Androgens
- Small amounts of sex hormones, which have small impact . (E.g. female hormone balance after menopause)
What does adrenal medulla release and what type of response does it cause?
- Short term response to stress - fight or flight.
- Inner region.
- Produces non-essential hormone.
- Releases adrenaline and noradrenaline, which prepared body for action, and steroid hormones.
What can these hormone cause?
1- Released smooth muscle in bronchioles -> widens airways, so more O2 in blood for breath per sec.
2- Increases HR and store volume of heart -> increases cardiac volume output - more O2 to cells increases respiration and ATP.
3- Vasoconstriction to increase BP -> Increase O2 in blood for breath per sec.
4- Conversion of glycogen -> glucose -> increase respiration and ATP.
5- Pupils dilate -> more light in.
6- Inhibits action of gut.
7- body hair erects -> deter predators.
Similarities of hormonal communication and neuronal communication.
- Both involve a stimulus being detected for a target cell to respond to it.
- Both involve molecules binding to receptor to trigger response.
Differences in hormonal and neuronal communication.
- Neuronal communication involves action potentials being transmitted along neurones, whereas hormonal communication involves hormones being released into bloodstream.
- The hormonal response takes longer and lasts longer, whereas neuronal response is much faster and much shorter lived.
- In the neuronal system, the sympathetic nervous system triggers nervous impulses to activate glands and smoot muscle. This activates adrenal medulla to release noradrenaline and adrenaline into bloodstream.
- In hormonal system, CRH and TRH is released which activates adrenal cortical system.
