endocrine system (3) Flashcards
how fast is the endocrine system
mins, hrs and days
way slower than the nervous system
what can be a gland and what is it made up of
organ or parts of an organ
many are made of endocrine tissue
what is in the endocrine system
endocrine glands and their respective hormones
how do hormones travel and what do they travel to
they diffuse directly into the blood (why glands are directly next to blood supply) until they reach their target cells
what are target and non target cells
target cells have receptors for a specific hormone who targets them (determined by genes)
non target cells dont have those receptors
what is the difference between a protein derived hormone and a steroid molecule
a protein derived hormone is water based while a steroid molecule is fat based
how do water based hormones interact with their target cells compared to fat based hormones
water based hormones will bind to receptors at the surface while fat based hormones will diffuse into the cell and bind to receptors inside
what are hormones
chemical messenger molecules
what are the five results of a hormones binding to a cell receptor
change in membrane permeability/potential by opening/closing ion channels
activate/inactivate enzymes
stimulate/inhibit mitosis and meiosis
promote/inhibit secretion of a product
turn on/off transcription of certain genes
how much hormone is required to create a change in target cells
pico amount
10^-12
what are the functions of hormones
reproduction
growth and development
mobilization of body defenses against stressors
homeostasis
regulation of metabolism
how do amino acid based hormones function compared to steroid hormones
protein based use second messenger system
steroid use direct gene activation
what is the water based hormone that uses direct gene activation
thyroid hormone (T3T4)
what are the steps of direct gene activation
steroid diffuses through the membrane and enters the nucleus
binds to a specific protein (receptor)
hormone-receptor complex binds to specific sites on dna
genes are activated to transcribe mRNA
new proteins are synthesized which either leave or stay in the cell
(can start or stop protein production)
what are the steps of the second messenger system
hormone (1st messenger) binds to membrane receptor
activated receptor triggers series of reactions that activate an enzyme
enzyme catalyzes a reaction which produces 2nd messenger molecule (cyclic AMP -> cAMP)
more reactions occur to promote a specific response in the cell
how are hormone levels maintained
by negative feedback
what are the types of stimuli that activate hormone glands and what are they
hormonal stimuli (other hormones)
humoral stimuli (change in levels of ions/nutrients)
neural stimuli (nerve fibers in sympathetic nervous system)
what are the 9 major endocrine organs
pineal gland
hypothalamus
pituitary gland
thyroid gland
parathyroid gland
thymus (not covered)
adrenal glands
pancreas
ovary/testes
what is the location and function of a pineal gland
middle of brain, dorsal
secretes melatonin (sleep/wake cycle)
location, characteristics and components of the pituitary gland
under hypothalamus, ventral in the brain (behind nose bridge), looks like balls, protected by sphenoid
made of anterior and posterior lobes
what is the function of the posterior lobe of the pituitary gland
storing hormones that are produced by the hypothalamus (oxytocin and ADH)
does not produce hormones
what is oxytocin and ADH
oxytocin: hormone released during childbirth and brestfeeding
ADH (antidiuretic hormone): stimulates kidneys to reabsorb water into blood (leads to dehydration)
how are hormones from the hypothalamus delivered to the posterior lobe of the pituitary
using neurosecretory cells
high concentrations of ADH leads to what
constriction of arterioles = high BP
what is diabetes insipidus and symptoms
disease caused by the hyposecretion of ADH, increased urination and dehydration
how is the activity of the anterior lobe of the pituitary controlled
by the hypothalamus producing releasing or inhibiting hormones which are then released in portal circulation
hormonal stimuli
what is portal circulation between the hypothalamus and the anterior lobe of the pituitary
network of blood vessels
what does the anterior pituitary release
peptide hormones:
growth hormones (GH)
prolactin (PRL)
follicle-stimulating hormone (FSH)
luteinizing hormone (LH)
thyrotropic hormone (TH/TSH)
adrenocorticotropic hormone (ACTH)
which of the hormones made by the anterior pituitary affect non endocrine targets
GH and PRL
what are the targets and functions of growth hormone (GH)
long bone and skeletal muscle growth
causes amino acid to be built into proteins and fat breakdown for fuel
what are the targets and functions of prolactin (PRL)
mammary glands (male function unknown)
stimulates and maintains milk production after childbirth
what hormones made by the anterior pituitary target endocrine tissues
and what are these hormones called
FSH, LH, TH/TSH, ACTH
tropic hormones
what are the targets and functions of follicle stimulating hormone (FSH)
ovaries and testes
stimulate follicle and sperm development
what are the targets and functions of luteinizing hormone (LH)
ovaries and testes
triggers ovulation of egg
stimulates testosterone production in males
what are FSH and LH also known as
gonadotropic hormones
what are the targets and functions of thyrotropic hormone (TH/TSH)
thyroid
stimulates growth and activity of thyroid gland
what are the targets and functions of adrenocorticotropic hormone (ACTH)
adrenal cortex
regulates the endocrine activity of the adrenal cortex
is the posterior lobe of the pituitary gland made of endocrine tissue
no because it doesnt produce hormones
what happens when there is a lot of GH in childhood, when there is not enough and when there is more in adulthood than usual
high levels in childhood: gigantism
low levels in childhood: pituitary dwarfism
high levels in adulthood: acromegaly
where is the location of the thyroid gland
in front of the trachea in the throat
bump/adams apple in neck
what are the components of the thyroid gland
left and right lobes
connected by an isthmus (bridge)
4 parathyroid glands at the back
what does the thyroid gland produce
thyroid hormone
calcitonin
thyroid hormone characteristics
almost all cells have receptors for it
controls metabolic rate of glucose oxidation (for energy and body heat)
maintains homeostasis (BP, HR, digestion, nerve and reproductive functions, etc)
needed for tissue growth and development
what are the two components of the thyroid hormone and what do they contain
T4 and T3
they contain iodine
what do T4 and T3 hormones do
T4 is secreted by the thyroid follicles (inactive form)
T3 is the active form of T4 which binds to receptors
T4 is converted into T3 at target tissues in the bloodstream
what endocrine organs coordinate metabolic regulation
hypothalamus
pituitary gland
thyroid gland
calcitonin hormone characteristics
decreases blood calcium by causing calcium deposition on bones (higher concentration when GH is high)
what is an antagonistic hormone and two examples
hormones that counter each other in raising/lowering levels of the same molecule
glucagon and insulin
calcitonin and parathyroid hormone
what are the four diseases of the thyroid gland, their causes and symptoms
simple goiter: lack of iodine in diet, no thyroid hormone is produced = swelling of the gland
hypothyroidism: not enough thyroid hormone = slow metabolism (weight gain, memory loss, lethargy, etc)
hyperthyroidism: too much TH = increased metabolism (high HR, sweating, weight loss, protruding eyes, etc)
cretinism: too little TH in fetal development/infancy = dwarfism, delayed mental and sexual development
what do the parathyroid glands produce and secrete
parathyroid hormone (PTH)
what are the functions of the parathyroid hormone (PTH)
increases blood calcium levels by stimulating osteoclasts to remove calcium from bone
stimulates the kidneys and intestines to absorb more calcium into blood vessels
antagonistic to calcitonin
the pancreas has functions in two organ systems, which ones
exocrine and endocrine
what part of the pancreas produces insulin and glucagon
pancreatic islets
glucagon and insulin are produced by which types of cells in the pancreas
glucagon is produced by alpha cells while insulin is produced by beta cells
insulin and glucagon functions
insulin is released when blood glucose levels are high, stimulates glucose uptake and metabolism by body cells
glucagon is released when blood glucose levels are low, stimulates liver to release glucose into the blood
how does diabetes work
after meals, blood glucose levels increase drastically
kidneys arent able to reabsorb glucose into the blood fast enough so glucose goes into the urine thats forming
by osmosis water follows the glucose
cells dont have energy so they break down fats and proteins = weight loss
fat breakdown causes blood to become acidic (acidosis/ketosis) which can lead to coma/death if blood pH gets lower than 7.3
what are the three signs of diabetes mellitus
polyuria (excess urination): used to flush out glucose and products of fat breakdown
polydipsia (excess thirst): to try to replace water loss from urination
polyphagia (hunger): to make up for loss of glucose, proteins and fats
characteristics of type one diabetes
insulin dependent diabetes mellitus (IDDM)
immune system destroys beta cells (no insulin is produced)
treatment: insulin injections for life
onset is sudden, before adulthood
characteristics of type two diabetes
non-insulin dependent diabetes mellitus (NIDDM)
target cells receptors have become less sensitive to insulin so theres high levels of blood glucose and insulin
treatment: change in diet, more exercise and potentially weight loss
where are the adrenal glands
on top of the kidneys
what are the components of the adrenal gland in order of most superior
adrenal cortex: mineralcorticoid secreting area, glucocorticoid secreting area, gonadocorticoid secreting area
adrenal medulla
adrenal gland hormones are water or fat based
fat based
cholesterol
what does the adrenal cortex produce
corticosteroid hormones
what is special about the adrenal medulla
its made of neural tissue
what is an example of mineralcorticoid
aldosterone
what is the target and function of aldosterone
kidney
regulates sodium and potassium blood content and as result regulates water and electrolyte balance
produced in outer adrenal cortex
examples of glucocorticoids
cortisone and cortisol
what is the function of glucocorticoid
promote normal cell metabolism
resist long term stressors by increasing blood glucose and providing energy
anti inflammatory properties
produced by middle layer of adrenal cortex
when are glucocorticoids released
when ACTH levels are high in the blood
what are examples of gonadocorticoids
androgens and estrogens
characteristics of gonadocorticoids
small amounts are made throughout life
most produced are male sex hormones (androgens) but some female is made
made in the lowest layer of the adrenal cortex
what parts of the adrenal gland respond to long term vs short term stress
short term is the adrenal medulla
long term is the adrenal cortex
what is the immune systems response to high cortisol levels
terminating the inflammatory response
when chronic stress (high levels of cortisol) occurs what happens to the body
high blood sugar
high BP
insomnia
hypothyroidism
poor digestion
poor immune system
constipation
what are the two hormones produced by the adrenal medulla and their category
epinephrine and norepinephrine (adrenaline and noradrenaline)
they’re called catecholamines
what stimulates catecholamines and what are their functions
stimulated by the nerve fibers of the sympathetic nervous system
prepare body for short term stress (fight or flight)
increase heart rate, blood pressure and blood glucose, dilating small passageways of lungs
what is the short term stress response
increased HR and BP
liver converts glycogen into glucose and release into the blood
dilation of bronchioles
changes in blow flow patterns (increased alertness and decreased digestive and kidney activity)
increased metabolic rate
what is the long term stress response and what does each
mineralocorticoids: retention of sodium and water by kidneys, increased blood volume and BP
glucocorticoids: proteins and fats are broken down for energy, increased blood sugar, suppressed immune system
