14.1 Hormonal Coordination Flashcards
Endocrine gland
Group of cells specialised to secrete hormones into the bloodstream
Pituitary gland functions
- produces growth hormone (growth of bones and muscles)
- ADH (reabsorption of water)
- gonadotropins (development of ovaries and testes)
Pineal gland function
Produces melatonin - affects reproductive development and daily cycles
Thymus function
Produces thymosin - promotes production and maturation of WBCs
Pancreas function
- insulin (glucose to glycogen conversion) when glucose levels increase
- glucagon (glycogen to glucose) when glucose levels fall
Ovary functions
- produces oestrogen - ovulation and secondary sexual characteristics
- progesterone - prepares uterus lining to receive embryo
Thyroid gland function
Produces thyroxine which controls rate of metabolism and rate that glucose is used up in respiration - promotes growth
Adrenal gland function
Produces adrenaline which increases heart and breathing rate and raises blood glucose level
Testes function
Produces testosterone - controls sperm production and secondary sexual characteristics
What happens when hormones are secreted?
Transported in blood plasma around the body
Hormones diffuse out of blood and bind to specific receptors for that hormone
Receptors are found in membranes/in cytoplasm of target organs - target cells
Two types of hormone
Steroid hormones
Non steroid hormones
Steroid hormones
Lipid soluble
Can pass through cell membrane
How do steroid hormones work?
Pass through cell membrane
Bind to steroid hormone receptor to form hormone receptor complex
Receptors can be in cytoplasm or nucleus
Hormone receptor complex acts as a transcription factor - can facilitate or inhibit transcription of a particular gene
Complex attaches to DNA, which provides instructions for synthesis of a polypeptide
Polypeptide synthesised by ribosomes and mRNA
Non steroid hormones
Hydrophilic
Cannot pass through cell membrane
How do steroid hormones work?
Bind to specific receptors on cell surface membrane of target cell
Triggers cascade reaction by second messengers
Communication in hormonal vs nervous system
Hormonal - hormones
Nervous - nerve impulses
Transmission in hormonal vs nervous system
Hormonal - blood, slow
Nervous - neurones, fast
Location of response in hormonal vs nervous system
Hormonal - travel to all parts of the body but only target organs respond
Nervous - travel to specific parts of the body
Response in hormonal vs nervous system
Hormonal - widespread, slow, long lasting
Nervous - localised, rapid, short lived
Effect in hormonal vs nervous system
Hormonal - permanent and irreversible
Nervous - temporary and reversible
Where are the adrenal glands found?
On top of each kidney
Structure of adrenal gland
Medulla, cortex surrounded by capsule
Adrenal cortex
Outer region of glands
Produces vital hormones eg - cortisol and aldosterone
Adrenal medulla
Inner region of the glands
Produces non essential hormones eg adrenaline
Main types of hormones produced by adrenal cortex
Glucocorticoids
Mineralocorticoids
Androgens
Glucocorticoids
Eg - cortisol
Regulate metabolism by controlling how body converts fats, proteins and carbohydrates to energy
Regulate blood pressure and cardiovascular function in response to stress
Eg - corticosterone
Regulate immune response and suppress inflammatory reactions
What controls release of glucocorticoids?
Hypothalamus
Mineralocorticoids
Aldosterone
Control blood pressure by maintaining salt and water concentrations in blood and fluids
What controls release of aldosterone?
Signals released by the kidney
Androgens
Small amounts of male and female sex hormones released
Hormones released by the adrenal medulla
Adrenaline
Noradrenaline
When are hormones released from adrenal medulla?
When sympathetic nervous system is stimulated - during stress
Adrenaline
Increase heart rate, blood is sent quickly to muscles and brain
Raises blood glucose concentration
Noradrenaline
Works with adrenaline
Increased heart rate, widening pupils
Wider air passages in lungs and narrow blood vessels in non essential organs
