endocrine system Flashcards
Pituitary gland
produces hormones that act on other endocrine glands and controls their hormone production
Thyroid gland
only gland that stores hormones until they are needed
Adrenal medulla
prepares body for physical activity
Pancreas
- exocrine gland
- endocrine gland
- alpha cells
- beta cells
exocrine gland
consists of pancreatic digestive juices
endocrine gland
consists of pancreatic islets
alpha cells
secrete glucagon
beta cells
secrete insulin
glucose levels after a meal vs when you are hungry
After a meal you have high blood glucose levels, so the pancreas makes insulin decreasing the blood glucose level
Hungry / fasting you have low blood glucose levels so the pancreas creates glucagon and the liver releases stored glucagon to increase blood glucose levels
structure of the pituitary gland.
2 parts
Posterier pituitary (neurohypophysis)
extension of hypothalamus
Axons from hypothalamohypophysial tract
2. Anterior pituitary (adenohypophysis)
secretes hormones
Blood vessels make up Hypothalamohypophysial portal system
hormone
Hormones are chemical messengers produced in one part of the body that affects cells in another part of the body
Endocrine
can affect distant organs with the correct response
Paracrine
regionally active
Autocrine
within a cell, from cell to neighbouring cell
negative feedback and give an example
inhibition or reduction by the hormone itself
Eg hypothermia
hypothermia cause TRH to be released from neurons in the hypothalamus passing through the Hypothalamohypophysial portal system into the anterior pituitary
TRH causes the anterior pituitary to secrete TSH
TSH causes increase synthesis and release of T3 and T4
T3 and T4 act on the target tissue
This then has an inhibitory effect on the secretion of TRH as the body temp is back to normal and it no longer is hypothermic
positive feedback and give an example.
stimulating / producing
Cycle continues until a big change occurs
Eg oxytocin during labour
the stretch of the uterus increases action potentials in axons
Action potentials are sent up to the hypothalamus
Hypothalamus responds by producing oxytocin which travels through axons in the hypothalamohypophysial tract
Oxytocin then enters circulation increasing contractions, and milk ejection
Continues until the baby is born
hormones released from the anterior pituitary
- TSH
- ACTH
- FSH
- LH
- GH
- prolactin
MSH
TSH meaning
thyroid stimulating hormone
TSH
tropic
stimulates thyroid to secrete T3 and T4
increases metabolism
Increases body temp
Increase normal growth and development
ACTH meaning
Adrenocorticotropic hormone
ACTH
tropic
stimulates adrenal cortex to secrete cortisol and aldosterone
androgens
cortisol
- anti stress
- regulates glucose
- regulates blood pressure
aldosterone
water and sodium balance and blood pressure
androgens
estrogen and testosterone development and maintenance of some sex characteristics
LH meaning
Luteinising hormone
FSH meaning
follicle stimulating hormone
LH and FSH
tropic
stimulate testes and ovaries to produce testosterone and oestrogen
- stimulate the development of sperm / oocyte and secondary sex characteristics
GH meaning
growth hormone
GH
tropic and non tropic
stimulates protein synthesis in liver
Promotes bone and cartilage growth
Peak levels during deep sleep
Prolactin
non tropic
- breast cells
- role in milk production
Supply and demand: the more the baby sucks the more is produced
MSH meaning
melanocyte-stimulating hormone
MSH
non tropic
skin cells
causes melanocytes to produce more melanin
hormones released from the posterior pituitary
ADH
Oxytocin
ADH meaning
Antidiuretic hormone
ADH
stimulates increased absorption of sodium and water from nephrons so less urine is produce
if BP decreases then the ADH secretion is stimulated
Keeps water in the body
Increases blood volume and therefore blood pressure
oxytocin
uterine contractions during birth, ejection of milk from lactating breast
positive feedback
nervous vs endocrine system
Nervous
instant
Milliseconds / seconds
Neurotransmitters
Nerve impulses (axons) Muscles and glands
endocrine
delayed
minutes / days
hormones
blood
cells
types of hormone secretion
Acute - sudden release due to stimulation eg adrenaline response to stress
Chronic - small variations over long period of time eg thyroid hormones
Episodic - oestrogen and progesterone during menstrual cycle
Tropic vs non-tropic
Tropic hormones - stimulates the secretion of other hormones from target tissues
Eg LH is released which talks to the gonads to produce testosterone
Non - tropic - initiate an effect
