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A Level Biology - Unit5 > Hormones > Flashcards

Flashcards in Hormones Deck (18):

What is the endocrine system?

The system which uses hormones to respond to changes alongside the neuronal system.


What is an endocrine gland?

A group of cells which are specialised to secrete chemical hormones directly into the bloodstream.


What is the role of the pituitary gland?
(talk about the hormones it secretes and what they control)

Growth hormone- controls growth of bones and muscles
Anti-diuretic hormone- increases re-absorption of water in the kidneys
Gonadotrophins-control development of ovaries and testes


What is the role of the thyroid gland?

Produces thyroxine- controls rate of metabolism and rate that glucose is used up in respiration. Also promotes growth.


What is the role of the adrenal gland?

Produces adrenaline-increases heart and breathing rate and raises blood sugar levels.


What is the role of the testis?

Produces testosterone- controls sperm production and secondary sexual characteristics.


What is the role of the pineal gland?

Produces melatonin- affects reproductive development and daily cycles.


What is the role of the thymus?

Produces thymosin- promotes production and maturation of white blood cells.


What is the role of the pancreas?

Insulin- converts glucose into glycogen in the liver
Glucagon- converts glycogen back into glucose in the liver


What is the role of the ovaries?

Oestrogen- controls ovulation and secondary sexual characteristics
Progesterone- prepares the uterus lining for receiving an embryo
Progesterone, oestrogen- controls secondary sexual charateristics


Describe briefly step by step the mechanism of hormone action on target cells.

1) Change in conc. of a substance stimulates a gland.
2) The gland secretes a hormone directly into the bloodstream.
3) The hormone is transported in the blood plasma
4) The hormone diffuses out of the blood and bind to a specific receptor on the membrane of target cells.
5) This triggers the target cell to produce a response.


How do steroid hormones affect a target cell?

When they bind to steroid hormone receptors they form hormone-receptor complexes that act as transcription factors which help or inhibit the transcription of a particular gene.


How do non-steroid hormones affect target cells?

They bind to receptors on the cell surface which triggers a cascade of reactions inside the target cell controlled by second messenger chemicals.


hormonal communication VS neuronal communication.
transmitted by?
communicated by?
speed of transmission?
signals travel where?
response speed?
how long response lasts?
effects are?

blood stream / neurones
chemicals / nerve impulses
slow / very fast
all parts of the body / specific parts of the body
slow / rapid
long-lasting / short-lived
permanent and irreversible / temporary and reversible


What are the adrenal glands?

They are 2 small glands found on top of each kidney.


What are the 2 parts that make up the adrenal glands?

The adrenal cortex and the adrenal medulla.


What are the 3 main hormones produced by the adrenal cortex?

Glucocorticoids- controls blood pressure, metabolism, immune response. Release controlled by hypothalamus.
Mineralocorticoids- controls blood pressure. Release is triggered by kidney.
Androgens- small amount of sex hormones important for after menopause in women.


What 2 hormones are secreted by the adrenal medulla?

Adrenaline- increases heart rate, raises blood glucose levels
Noradrenaline- increase heart rate, widen pupils, widen air passages to lungs, narrowing blood vessels in non-essential organs.