endocrine system Flashcards
what are hormones
chemicals released from one part of the body and carried through the bloodstream to affect another part of the body
hormones are released in — quantities and are very —.
small; specific
how do hormones know which cells to affect?
target cells have receptors for specific hormones. if the hormones contact cells without these target cells, they will have no effect.
two types of hormones
- water soluble (non-steroid/amino acid)
- lipid soluble (steroids)
water soluble (non-steroid/amino acid)
- bind to receptors on the outside of the target cell, which activates a 2nd messenger to mediate the response to the target cell
- not able to pass through membrane
lipid soluble (steroids)
- can pass directly through target cell membrane forming a hormone receptor-complex, which alters the actions of the cell
three ways to activate glands
hormonal stimuli, humoral stimuli, neural stimuli
hormonal stimuli
glands are encouraged by hormones secreted by other cells (hypothalamus stimulates pituitary gland)
humoral stimuli
levels of nutrients and ions in the blood can cause glands to secrete hormones (blood-calcium levels stimulate parathyroid glands)
neural stimuli
nerve impulses cause glands to secrete hormones (sympathetic NS during stress causes release of epinephrine from adrenal glands)
pituitary gland
- small bulb on the underside of the brain
- has two lobes: anterior and posterior pituitary glands
growth hormone
stimulates growth in bones and muscles
anterior pituitary gland
GMPLAFT
- Growth hormone
- Melanocyte-stimulating hormone
- Prolactin
- Luteinizing hormone
- Adrenocorticotropic hormone
- Follicle-stimulating hormone
- Thyroid-stimulating hormone
melanocyte-stimulating hormone
stimulates melanocytes to produce melanin
Prolactin
stimulates breast milk production
Luteinizing hormone
stimulates release of sex hormones
Adrenocorticotropic hormone
stimulates adrenal glands
Follicle-stimulating hormone
stimulates egg/sperm production
Thyroid-stimulating hormone
causes thyroid to produce thyroxin
why is the pituitary gland called the master gland?
it controls many other glands in the body
posterior pituitary gland
- Antidiuretic hormone
- Oxytocin
antidiuretic hormone
(ADH or vasopressin) increases water retention in kidneys, decreasing urine production
oxytocin
stimulates contraction of uterus during childbirth and promotes release of breast milk
hypothalamus
- located right above the pituitary gland and is about the size of an almond
- main function is to control the pituitary gland by hormonal and neural stimulation
–> CCCRRR
—> control of brain stem and spinal cord
—> controls thirst
—> center of emotional response
—> regulation of food intake
—> regulation of body temp
—> regulates sleep and wake cycles
pineal gland
- tiny, cone-shaped gland near the cerebellum
- main secretion of the pineal gland is melatonin, which regulates sleep and wake cycle
thyroid gland
- located at the base of the neck
- two distinctive halves resulting in a butterfly shape
- calcitonin, thyroxine, and triiodothyronine are released
–> calcitonin: reduce Ca+ levels in blood
–> thyroxine (T4) and triiodothyronine (T3): regulate metabolism and body heat production
parathyroid gland
- attached to the back of the thyroid
- produce PTH which brings Ca+ out of bones and into the bloodstream
adrenal glands
- sit atop of each kidney
- outer layer: adrenal cortex
–> secretes glucocorticoids: regulate ion levels for quick energy (cortisol and aldosterone) - inner layer: adrenal medulla
–> secretes epinephrine and norepinephrine: regulates the fight or flight to emergency situations (high heart rate, blood pressure, blood flow, etc)
pancreas
- the endocrine part of the pancreas is made of groups of cells called the islets of Langerhans that look like tiny islands, they produce insulin and glugagon
- pancreas –> beta cells –> insulin –> lower blood glucose levels
- pancreas –> alpha cells –> glucagon –> raise blood glucose levels
thymus
- small gland found near the sternum
- produces thymopoietin, thymic factor, and thymosin, which is involved in the development of the immune system
gonads
reproductive organs that produce sex cells and secrete sex hormones
–> females: ovaries
—> estrogen: maturation of reproductive organs and secondary sex characteristics
—> progesterone: breast development and control of menstrual cycle
–> males: testes
—> testosterone: same as estrogen, and produces sperm
