the endocrine system Flashcards
definition of the endocrine system
a system comprising feedback loops of hormones released by internal organs
endocrine glands
are glands that manufacture hormones
target cells
hormones try to bind to those cells to activate them
pineal gland
it produces melotonin when light levels are low to make you sleepy
it controls your sleep/awake schedule
thymus gland
only active until puberty, is then slowly replaced by fat
produces thymosin; stimulates the thymus to turn lymphocytes into T-cells
homeostesis
is the ability to maintain a relatively stable internal state
what are the three parts of the homeostesis?
receptor; change is sensed by a receptor
control or coordinating centre; gets the info and redirects it to the effector
the effector; responds and feeds back causing a stimulus to change and to return to the homeostesis
negative feedback
when levels of a hormone become too high, a message is sent to the producing gland to stop the release of that hormone
Hypothalamus
produces ADH and oxytocin and sends them to the pituitary for storage
pituitary gland
master gland, composed of gland tissues not neurons
is devided into posterior and anterior halves
anterior half of the pituitary
that’s where the pituitary glands come from
posterior half of the pituitary
that’s where the extension of the hypothalamus is (store ADH and oxytocin)
hGH
aka human growth hormone
stimulates bone and muscle growth throughout the body
hGH negative feedback loop
stimulus: need for growth
hypothalamus releases a releasing hormone
pituitary releases hGH
effect: muscle and bone growth
disorders connected to the hGH
gigantism: hypersecretion during development ( bone plates have not been fused yet)
Acromegaly after the development, bone plates have been fused, hypersecretion of hGH results in muscle growth( especially the heart)
thyroid gland
located in front of the trachea
produces thyroxin and calcitonin
thyroxine
increases metabolism ( burn of sugar to make ATP)
it contains iodine
it speeds up the metabolism and strength and rate of the heart beat
thyroxin is also released when theperson is cold
thyroxin feedback loop
stimulus: cells need enery
hypothalamus releases thyroid releasing hormone
pituitary releases thyroid stimulating hormone (TSH)
thyroid releases thyroxine
result: metabolsim increase and more ATP
what happens when thyroxin increases?
metabolsim increases
weight loss
feels warm
what happens when thyroxin levels are low?
low metabolism, less sugar oxidized
weight gain
feel cold
