Endocrine System Flashcards
homeostasis
keep a constant internal environment in the body
endocrine glands
glands that release secretions directly into the bloodstream which transports it to the target organs so it can perform its function
exocrine gland
glands that release their secretions via ducts to a body cavity or the outside
eg.) saliva
hormones
- organic compounds which are chemical messengers
- some are proteins, some are steroids
which gland secretes hormones
endocrine gland
negative feedback
- regulates the secretion of hormone by stimulating or inhibiting
- caused by a deviation from normal levels
relationship between hypophysis and hypothalamus
- connected via neurons and posterior lobe
- thalamus produces hormones which are stored in physis
- thalamus controls physis by secreting releasing factors which stimulate physis to produce +/ release hormones
hypophysis location
- fits into small bony cavity in cranium
- attached to thalamus by a small stork
two lobes of hypophysis
anterior and posterior lobe
hormones in anterior lobe
TSH STH (growth hormone) FSH LH Prolactin
STH
growth hormone
promotes growth of the skeleton and muscles by stimulating protein synthesis
undersecretion = dwarfism
oversecretion = gigantism
hypo/hypersecretion
hyper = over hypo = under
FSH
stimulates follicle development in the female ovary / produces sperm cells
LH
- stimulates female ovulation
- stimulated cells to produce testosterone
prolactin
stimulates mammary glands to produce breast milk
hormones of posterior lobe
ADH
thyroxin
ADH
- produced by hypothalamus
- when water level DEC, ADH release INC
- osmoreceptors detect change
ADH function
controls the reabsorption of water by making renal tubule walls more permeable to water
thyroid consists of…
two lobes between the larynx and trachea
thyroxin function
increases basal metabolic rate
increases breathing/heart rate
essential for functioning of nervous system
thyroid disorders
oversecretion = increased metabolic rate, weight loss, increased heart rate
undersecretion = leads to cretinism in children
how is thyroxin levels in the blood controlled
kept constant by a negative feedback mechanism between hypophysis and thyroid
process of thyroxin negative feedback
as soon as levels drop, hypophysis secretes more TSH increasing the level of thyroxin being secreted. when levels rise above normal, TSH secretion is inhibited
TSH
stimulates the thyroid to secrete more thyroxin
cells the pancreas is made up of…
exocrine pancreatic
endocrine islets of Langerhans
pancreatic cells
secrete pancreatic juice into the pancreatic duct to aid chemical digestion
islets of Langerhans
secrete hormones directly into bloodstream
insulin
decreases the glucose level
produced by beta cells
glucagon
increases glucose level
produced by alpha cells
process of glucose levels changing
normal level level changes islets detect the change, hormone secreted stimulates conversion/absorption glucose is added/removed from blood normal
diabetes mellitus
- disease characterized by high glucose levels in blood
- no cure
symptoms of diabetes
frequent urination
++ hunger
++ thirst
weight loss
type 1 diabetes
the loss of beta cells in the pancreas, less insulin produced
- special diets, injections
type 2 diabetes
insulin is produced but the body cannot use it effectively
- obesity, age
- medication + exercise
adrenal glands structure
located at the top of each kidney; has an outer cortex and inner medulla
hormones of adrenal cortex
aldosterone = regulates amount of sodium in the body
= increases sodium absorption
hormones of adrenal medulla
adrenalin = secreted during stressful situations / fight or flight hormone
= prepares the body for action in emergencies
effects of adrenalin on body
- accelerates/strengthens heart rate
- inc blood pressure
- inc rate and depth of breathing
- dilates pupil
- inc sweat productionq
gonads
ovaries in women (in scrotum)
testes in men (on either side of uterus)
testosterone
- secreted by Leydig cells
- resp for 2ndary male characteristics
- helps w the development of sex organs
- helps w maturation + quality of sperm
oestrogen
- secreted by developing follicles
- resp for 2ndary female characteristics
- helps w development of sex organs
- inhibits secretion of FSH
