Hormonal communication Flashcards
What is the endocrine system?
Contains endocrine glands
~~>secrete hormones into blood plasma to target cells
—> have receptors to a hormone
What is a hormone?
Chemical messenger
Carry information from one part of body to another.
Steroids,
Proteins,
Glycoproteins,
Polypeptides,
Amines,
Tyrosine derivatives.
What is a peptide hormone?
E.g: adrenaline
Hydrophilic
Cannot pass cell surface membrane
Binds through receptor
First messenger = carries message
Turns ATP into cAMP
~~>cascade of reactions
What are steroid hormones?
E.g: oestrogen
Lipid based
Diffuse across membrane
Receptor inside the cell
Hormone-receptor complex formed acts as a transcription factor.
What is the thyroid gland responsible for?
Produce thyroxine
Controls rate of metabolism
Controls rate of glucose used up in respiration
Promotes growth
Role of pituitary gland?
Produces growth hormone
ADH –> increases reabsorption in kidneys
Role of thymus:
Produces thymosin
Promotes production + maturation of WBC
What are differences between hormonal communication and neuronal communication?
Chemicals vs Nerve impulses
Blood vs Neurones
Widespread vs Localised
Slow vs Rapid
Long-lasting vs Short-lived
All parts of body vs Specific parts of body
What is the adrenal cortex?
Outer later of adrenal gland
Releases steroid hormones when stimulated by pituitary gland.
Describe function of glucocorticoids?
Regulate metabolism
~~>control how fat/protein/carbs converted into energy
Regulates BP
Suppresses inflammatory response
Describe role of mineral corticoids:
Aldosterone
Maintains salt concentration to control BP
Describe roles of androgens:
Small amount of sex hormones
Important for women after menopause
What is the adrenal medulla?
Inner region
Produces non-essential hormones
Peptide hormones
Stimulated by sympathetic nervous system.
Describe role of adrenaline:
Increase heart rate
Increase blood glucose levels
~~>converts glycogen into glucose in liver
Describe role of noradrenaline:
Dilates pupils in eyes
Vasoconstriction of vessels to non-essential organs
What is a coordinated response?
Body-wide response, controlled by both nervous + endocrine system
What happens when body detects a threatening stimuli in neuronal response ?
Activates autonomic NS
Triggers hypothalamus
Activates sympathetic NS
Signals muscles = move
What happens when body detects threatening stimuli in hormonal response?
Sympathetic NS —> signals adrenal medulla
Release adrenaline + noradrenaline
Hypothalamus release CRF
Stimulates pituitary glands
Release ACTH = signals adrenal cortex
Releases 30 steroid hormones.
Released in bloodstream
How is adrenaline involved in cell signalling?
Adrenaline = 1st messenger
Binds to inactive adenyl cyclase
Causes conformational change
ATP —> cAMP (2nd messenger)
Bind to other enzyme –> protein kinase
(phosphorylation) = activate other enzymes
Converts glycogen into glucose
What does an ‘enzyme cascade effect’ mean?
One hormone cause multiple enzymes to be activated for various actions.
What are baroreceptors?
Detect changes in blood pressure.
Low BP = heart rate increase to prevent fainting.
Present in aorta, vena cava, and carotid arteries.
What are chemoreceptors?
Detect changes in the level of particular chemicals in the blood (CO2)
Detects pH of blood
Located in aorta, carotid artery (major artery in neck –> supplies the brain with blood), medulla
What do the nervous + endocrine system both do?
Signal SAN to increase/decrease heart rate
Depends on:
BP
pH of blood
Stress responses
How does the adrenal medulla cause increase in heart rate?
Release adrenaline/noradrenaline
Bind to SAN
~~>affect frequency of pulses being released
How is the medulla oblongata responsible for controlling HR?
Baro/chemoreceptors detect BP or pH change
Send impulse to medulla oblongata
What happens if there is a detected decrease in BP or pH?
Cardiostimulatory centre triggered
~~>sends impulse via accelerator nerve to SAN
~>increase HR
What happens if there is a detected increase in BP or pH?
Cardioinhibitory centre triggered
~~>sends impulse via vagus nerve to SAN
~>decreases HR
