Endocrine System Flashcards
what does the endocrine system do?
act with the nervous system to coordinate activity of body cells
influences metabolic activities via hormones
what are hormones?
chemical substance produced by ductless endocrine gland
what are the responses like for hormones vs nervous system?
slower but longer lasting
what are endocrine hormones like vs exocrine?
endocrine:
- ductless
- secretes directly into the blood stream
exocrine:
- ducts
- secretes into duct for storage until needed
what does the endocrine system control?
reproduction
growth and development
maintenance of electrolytes, water, nutrient balance of blood
regulation of cellular metabolism and energy balance
mobilization of body defenses
what structures are endocrine glands?
pituitary adrenal thyroid parathyroid pancreas testes and ovaries
what are the other tissues and organs that secrete hormones?
adipose cells hypothalamus cells in walls of small intestine stomach liver kidneys bone heart
what is the endocrine chemical signaling?
long distance
travels in blood
what is the autocrine chemical signaling?
chemicals that exert effects on the same cells that secrete them
(not always hormones)
what is the paracrine chemical signaling?
locally acting chemicals that affect cells other than those that secrete them
(not always hormones)
what are water soluble hormones?
all amino acid based hormones EXCEPT thyroid hormone
peptides/proteins, amines
what do water soluble hormones do?
act on plasma membrane receptors
act via G protein second messengers
cannot enter cell
what are lipid soluble hormones?
steroid and thyroid hormones
what do lipid soluble hormones do?
act on intracellular receptors that directly activate genes
can enter cell (act directly on plasma membrane)
which hormones are water soluble and located on the cell surface?
amine (epinephrine) and peptide/protein
which hormones are lipid soluble and found intracellular?
amine (thyroid hormone)
steroids and vitamin D
what is the connection for the hypothalamus?
hypothalamus is connected to pituitary gland (hypophysis) via stalk called infundibulum
what are the two major lobes of the pituitary?
posterior pituitary (neurohypophysis) anterior pituitary (adenohypophysis)
how does the posterior pituitary maintain neural connection to hypothalamus?
via hypothalamic-hypophyseal tract
–> arises from neurons in paraventricular and supraoptic nuclei in hypothalamus
what does the posterior pituitary do?
stores oxytocin and antidiuretic hormone (ADH)
–> released in response to nerve impulses
what does oxytocin do?
“cuddle hormone”
- stimulates uterine contractions during childbirth - pitocin is artificial form
- triggers milk ejection
- regulated by positive feedback
- stored in the posterior pituitary - made by paraventricular nuclei
what does the antidiuretic hormone do?
retain urine
vasopressin vasoconstricts blood vessels
targets renal tubules of the kidneys through cAMP 2nd messenger
- when solute levels return to normal osmoreceptors turn off production of ADH
^ this is negative feedback
diuretics inhibit ADH
what happens when there is an ADH deficiency?
diabetes insipidus:
- huge urine output, intense thirst
what inhibits ADH which makes you pee a lot?
alcohol
what is the anterior lobe an extension of? what does it consist of?
extension of oral mucosa called Rathke’s pouch
consists of glandular tissue
** no direct neural contact with the hypothalamus
what is the hypophyseal portal system?
capillary system that begins at the hypothalamus and drains into capillaries at the adenohypophysis
what are the 6 peptide hormones of the adenohypophysis (anterior pituitary)?
Follicle -stimulating hormone (FSH) Lutenizing hormone (LH) Adrenocorticotropic hormone (ACTH) Thyroid-stimulating hormone (TSH) Growth hormone (GH) Prolactin (PRL) Melanocyte-stimulating hormone (MSH)
“FLAT Gray Possum”
what are tropic hormones? what does that mean?
TSH, ACTH, LH, FSH
hormones that regulate secretory action of other endocrine glands
What are the direct hormones? what do they do?
GH and PRL
go directly to cells/tissues
which hormones from the hypothalmus turn into growth hormone?
growth hormone- releasing hormone
somatostatin
which hormones from the hypothalamus turn into prolactin?
prolactin-releasing factor
prolactin-release inhibiting hormone
which hormone from the hypothalamus turns into thyroid-stimulating hormone?
thyrotropin-releasing hormone
which hormone from the hypothalmus turn into adrenocorticotropic hormone?
corticotropin-releasing hormone
which hormone from the hypothalmus turns into luteinizing hormone and follicle-stimulating hormone?
gonadotropin-releasing hormone
where is growth hormone produced?
in the anterior lobe of the pituitary by the somatotropic cells
what does growth hormone do?
stimulates liver, muscle, bone and cartilage to produce insulin like growth factors
release increased breakdown of fats and glycogen stores for fuel
what if there is hypersecretion of GH?
it is secreting more than normal amounts
- in children: gigantism (really tall)
- in adults: acromegaly (enlarged features)
what if there is hyposecretion of GH?
secretes less than normal amounts
- in children: pituitary dwarfism
what does thyroid stimulating hormone do?
stimulates normal development and secretory activity of thyroid gland
regulation of TSH release
stimulates production of thyroid hormones via second messenger system
what does adrenocorticotropic hormone do?
stimulates adrenal cortex to release corticosteroids via 2nd messenger
inhibited by increased levels of glucocorticoids
- negative feedback (like a thermostat)
what is the function of follicle stimulating hormone FSH?
targets ovaries and testes to stimulate gamete production
“fish” - sperm swim, fish have eggs
what does LH do?
in women: triggers ovulation, promotes synthesis, release estrogen and progesterone from ovaries
in males: stimulates interstitial cells of testes to produce testosterone
FSH and LH in women work together for maturation of ovarian follicle
what does prolactin do?
stimulates milk production
what does thyroid hormone do?
major metabolic hormone
amino acid - direct gene activation
increases metabolic rate and body heat production by stimulating enzymes used in glucose metabolism
what two iodine containing compounds are in thyroid hormone?
T4- thyroxine
T3 - triiodothyronine
what is hypothyroidism?
low secretion of TH
adults: Myxedema (lack of iodine): low metabolic rate, chilled, lethargy
children: cretinism: mental retardation
what is hyperthyroidism?
Grave’s disease: autoimmune disease - over production of TSH-like antibodies (goiter)
elevated metabolic rate, sweating, nervousness
what is calcitonin?
produced by parafollicular cells in thyroid gland
released in response to high calcium levels
- targets skeleton (inhibits osteoclasts)
- stimulates calcium uptake and deposition into bone (lowers blood calcium levels)
inhibited by low blood calcium levels via negative feedback
what are parathyroid glands?
4-8 tiny glands embedded in posterior thyroid
what is parathyroid hormone?
most important hormone in calcium homeostasis
stimulates bone reabsorption - increases calcium levels, activates osteoclasts
what is hyperparathyroidism?
bones soften and deform (osteitis fibrosa cystica)
elevated blood calcium depresses nervous system - contributes to kidney stones
what is hypoparathyroidism?
increases excitability of muscles
–> results in tetany, respiratory paralysis and possibly death
what are adrenal glands and what do they do?
on top of kidney - adrenal hormones help body cope with stressful situations
what is the structure and function of the adrenal glands?
two glands in one:
1 - adrenal medulla (inner layer)
- nervous tissue
- part of sympathetic nervous system
2 - adrenal cortex (outer layer)
- three layers of glandular tissue that synthesize and secrete corticosteroids
- all hormones produced here work via direct gene activation
what are the three layers of the adrenal cortex and the corticosteroids primarily produced within?
1 - zona glomerulosa - minerALocorticoids --- main one: aldosterone 2 - zona fasciculata - glucoCORticoids --- main one: cortisol/hydrocortisone 3 - zona reticularis - gonadocorticoids (sex hormones) --- main ones: androgens (male sex hormones)
what is the most potent mineralcorticoid?
aldosterone
- stimulates Na+ reabsorption and water retention by kidneys
- considered an antidiuretic
- stimulates K+ excretion/elimination
what are glucocorticoids (cortisol)?
keep blood sugar levels constant
major group released in stress
negative feedback
what are gonadocorticoids? (sex hormones)
most are androgens (male sex hormones)
- converted into testosterone in tissue cells or estrogen in females
what do androgens contribute to?
onset of puberty
appearance of secondary sex characteristics
sex drive in females
what do acinar cells do (exocrine)?
they produce enzyme rich juice used for digestion
what organ has both exocrine and endocrine cells?
pancreas
what contains the endocrine cells in the pancreas?
what are their major cell types?
pancreatic islets
alpha cells - produce glucagon
beta cells - produce insulin
gamma cells - secrete somatostatin
what causes diabetes mellitus?
hyposecretion or hypoactivity of insulin
what are the 3 cardinal signs of DM?
- polyuria: huge urine output
- polydipsia: excessive thirst
- polyphagia: excessive hunger and food consumption
what is type I diabetes?
insulin dependent
early onset, total lack of insulin production
what is type II diabetes?
non-insulin dependent
late onset
inefficient insulin receptors
what do paired ovaries in the abdominopelvic cavity produce?
- estrogen: maturation of reproductive organs, appearance of secondary sex characteristics
- progesterone: breast development, menstrual cycle
for what does the testes produce testosterone?
- initiates maturation of male reproductive organs
- causes appearance of secondary sex characteristics
- necessary for sperm production
- maintain reproductive organs in their functional state
what is osteoporosis and what is it associated with?
loss of bone mass
usually in postmenopausal women - decline in estrogen
