B3.2 -Endocrine System Flashcards
state three endocrine glands
- Thyroid gland
- Pituitary Gland
- Pancreas
Where is the thyroid gland and what does it do?
- in the neck, releases thyroxine (increases resting metabolic rate)
- thyroxine plays a vital role in regulating the body’s metabolic rate - the speed at which the body transfers energy from its chemical stores in order to perform its functions
what is the pituitary gland known as?
where is the pituitary gland?
what does the pituitary gland realse (and when)?
what is key about the pituitary gland?
- known as ‘master gland’
- found in brain, linked to hypothalamus
- releases hormones in when changes are detected by hypothalamus
- many hormones trigger other glands to release more hormones
where is the pancreas and what does it do?
- found below rib cage
- produces insulin and glucagon
- regulates blood glucose level
where are the adrenal glands?
what do they do? (and when do they do so)
- two glands, situated above each kidney
- produce adrenaline (when an organism is presented with a dangerous situation)
where are the testes and what do they do?
- producest testosterone (controls puberty and sperm production)
what do ovaries do?
- produce oestrogen
- regulates menstrual system
how do hormones travel around the body?
being secreted in the blood and transported
what is homeostasis?
keeping the conditions in your body constant
The maintenance of a constant internal environment in the body.
state the function of a hormone
a chemical messenger which regulates the function of many cells and organs
how do hormones produce a response in target cells from the blood?
diffuse out of bloodstream and bind to specific receptors for that hormone (on cytoplasm of cells for target organ)
what is the endocrine system?
name given to all the endocrine glands and the hormones that they produce
state the function of all the endocrine glands
controls and co-ordinates body processes with the nervous system
compare the speed of communication between CNS and endocrine gland?
- endocrine system triggers a slow response
- CNS triggers a fast response
compare the method of transportation between CNS and endocrine gland?
- CNS electrical impulses along axon of a neurone
- ES secreted in bloodstream
compare the duration of response between CNS and endocrine gland?
- CNS short acting
- ES longer acting (except hormones like adrenaline)
compare the area targeted between CNS and endocrine gland?
- CNS very precise area
- ES larger area (target organs)
similarities between CNS and endocrine system?
- both follow basic response oder
receptor cell, coordination centre, effector
what it the function of the thyroid gland?
- release thyroxine
- take iodine (from food) and convert it to thyroxine by combining it with the animo acid tyrosine
what does adrenaline prepare the body for?
intensive action
what is an important control in homeostasis?
negative feedback loop
how does adrenaline affect the lungs?
- enlarges air passages (alters metabolism)
- boosts delivery of oxygen and glucose to brain and muscles
how how does adrenaline affect the body?
Adrenaline causes the body to respond by:
- respiring more quickly, to increase rate of ATP production
- increasing rate of breathing, to the cope with extra demand of oxygen
- increasing heart rate
- diverting blood away from areas such as the digestive system towards the muscles
describe stages of a negative feedback loop
- conditions in the body change from a set point
- change detected by a receptor
- corrective mechanisms activated by an effector
- conditions returned to set point
- corrective mechanisms switched off
describe stages of a negative feedback loop (in terms of thyroxine)
- hypothalamus detects cells need more energy
- pituitary gland releases TSH
- thyroid produces thyroxine
- hypothalamus detects cells have enough energy
- pituitary gland stops producing TSH
- thyroid stops producing thyroxine
Low thyroxine levels in the bloodstream stimulate the hypothalamus to release TRH (Thyrotropin releasing hormone) and this causes the pituitary to release TSH so the thyroid releases more thyroxine. So blood levels return to normal.
what happens when the stress is removed (adrenaline)?
When stress is removed, the brains signals to the adrenal glands stop —> the glands stop producing adrenaline —> the affected body systems return to their previous state
what are the four key hormones of the menstrual cycle?
- FSH (follicle stimulating hormone)
- Oestrogen
- Luteinising Hormone (LH)
- Progesterone
what is FSH, and what does it do?
- Follicle stimulating hormone
- secreted by the pituitary gland
- travels to the ovaries where it causes an egg to mature
- also stimulates production of oestrogen
what is Oestrogen?
- made and secreted by ovaries
- causes lining of the uterus to build up
- as oestrogen levels rise, they inhibit the production of FSH — usually prevents more than one egg maturing
- also stimulates the pituitary gland to release luteinising hormone
What is LH?
- Luteinising Hormone
- when LH levels reach a peak in the middle of the cycle, ovulation is triggered (egg released, approx 14 days after it starts to mature in one of the ovaries)
what is progesterone?
- produced in ovaries after ovulation
- maintains lining of the uterus during days 14-28
- levels remain high throughout pregnancy
- inhibits the release of LH and FSH.
what happens when progesterone levels drop?
- triggers the breakdown of the lining
- marks day 1 of the next menstrual cycle.
what is stage 1 of the menstrual cycle?
- uterus lining breaks down, resulting in period
Stage 2 of menstrual cycle?
-uterus lining starts to build up again into a thick, spongy layer full of blood vessels.
stage 3 of menstrual cycle?
- Ovulation
- an egg is released from one of the ovaries
stage 4 of menstrual cycle?
- uterus lining is maintained, ready for the arrival of a fertilised egg
- if egg not fertilised, uterus lining breaks down, cycle restarts
what does the progesterone only pill do?
+ consideration
- thickens mucus in cervix, stopping sperm from reaching an ovum
- also thins lining of uterus, preventing implantation
- and can prevent ovulation
- taken around same time every day
Allegedly:
- fewer side effects than combined pill (but as effective)