endocrine physiology Flashcards
describe the relationship between the endocrine and nervous system
both systems work together, but the nervous system can override the endocrine system at any time
what is a hormone
chemical substance produced by a ductless endocrine gland that has specific regulatory effects on a target cell or organ
why are nervous system responses faster than endocrine system responses
the nervous system is composed of action potentiald
what is an endocrine gland
ductless gland
secretes product directly into blood stream
what is an exocrine gland
duct
secretes product into the duct until its needed
list the endocrine glands
pituitary adrenal thyroid parathyroid pancreas testes ovaries
define autocrines
chemicals that exert effects on same cells that secrete them
define paracrines
locally acting chemicals that affect cells other than those that secrete them
what hormones are water-soluble
amino acid-based (catecholamines), but not thyroid hormones
what is the function of water soluble hormones
act on plasma membrane receptors as second messengers
what are the lipid soluble hormones
steroid and thyroid hormones
where are amine hormones (epinephrine) located on the cell
water or lipid-soluble
cell surface
water-soluble
where are amine (thyroid) hormones located on the cell
water or lipid-soluble
intracellular
lipid soluble
where are peptide/protein hormones located on the cell
water or lipid-soluble
cell surface
water soluble
where are steroids and vitamin D located in the cell
water or lipid-soluble
intracellular
lipid-soluble
what is another name for the posterior pituitary
neurohypophysis
what is another name for the anterior pituitary
adenohypophysis
what are the contents within the posterior pituitary/neurohypophysis
what is the function
neural tissue
maintains neural connection to the hypothalamus via hypothalamic-hypophyseal tract
stores ADH and oxytocin
what is the function of oxytocin
stimulates uterine contraction during childbirth stimulated milk let down sexual arousal in both sexes promotes nurturing behavior regulated by positive feed back
what is the artificial form of oxytocin
pitocin
what is the function of ADH
inhibits urination
what is the action of ADH to inhibit urination
targets renal tubules (collecting ducts) of the kidneys through cAMP 2nd messengers
causes collecting ducts to reabsorb more water during times of high blood solute levels
how is ADH regulated
negative feedback - keeps levels in normal ranges and stops release when hormones reach normal ranges
ADH deficiency can lead to what chronic disease
diabetes insipidus
what pathology can cause ADH hypersecretion
meningitis in children
neurosurgery, trauma, cancer cells,
after general anesthesia (can lead to SIADH)
how is the anterior pituitary controlled
controlled by the hypothalamic hormones via the hypophyseal portal system
describe the hypophyseal portal system
capillary system that begins at the hypothalamus and drains into capillaries at the adenohypophysis
pathway by which inhibiting or releasing hormones from hypothalamus controls the adenohypophysis
what are the 6 peptide hormones of the adenohypophysis
follicle-stimulating hormone (FSH) luteinizing hormone (LH) adrenocorticotropic hormone (ACTH) thyroid-stimulating hormone (TSH) growth hormone (GH) prolactin (PRL) melanocyte-stimulating hormone (MSH)
what are the hormones released by the anterior pituitary that are considered tropic hormones
what is the function of tropic hormones
FSH, LH, ACTH, TSH
regulate the secretory action of other endocrine glands
what anterior pituitary hormones are considered direct hormones
what is the function of a direct hormone
GH and PRL
go directly to the cells/tissues
what is the function of FSH
targets ovaries and testes to stimulate gamete production
what is the function of LH
women: triggers ovulation, promotes synthesis and release of estrogen and progesterone from ovaries
men: stimulates interstitial cells of the testes to produce testosterone
what triggers the release of adrenocorticotropic hormone (ACTH)
corticotropin releasing hormone
what is the function of adrenocorticotropic hormone (ACTH)
stimulates adrenal cortex to produce and secrete glucocorticoids
leads to increase in blood levels of nutrient molecules (glucose, glycerol, fatty acids, amino acids
what is the function of thyroid-stimulating hormone (TSH)
stimulates normal development and secretory activity of thyroid gland
stimulates the production of thyroid hormones via second messenger systems
how is TSH release regulated
TSH is released in response to thyrotropin-releasing hormone (TRH)
inhibited in response to rising blood levels of thyroid hormones to block to release of TSH
negative feedback
where is growth hormone (GH) produced
anterior lobe of the pituitary gland by the somatotropic cells
what hormone regulates the growth hormone
growth hormone-releasing hormone (GHRH)
growth hormone inhibiting hormone (GHIH)
what is the action of growth hormone
stimulates the liver, skeletal muscle, bone, and cartilage to produce insulin-like growth factors
increases breakdown of fats and glycogen stores for fuel
what pathology can occur with hypersecretion of growth hormone in children
gigantism
due to excessive GH secreted before epiphyseal plate closure
what pathology is common with hypersecretion of GH in adults
acromegaly
excessive GH secretion after epiphyseal plates close
can be seen in nose, jaw, internal organs, supraorbital ridge, hands, feet
what common pathology can result from excessive growth hormone release in all ages
hyperglycemia, can lead to diabetes
what pathology is common with hyposecretion of growth hormone
pituitary dwarfism
can be treated with GH injections
what is the function of prolactin
stimulates milk production
suckling stimulates PRH release
how is prolactin (PRL) regulated
prolactin-inhibiting hormone (PIH)
what is the precursor of thyroid hormone (TH) and is found within the follicles of the thyroid
colloid
what is the function of the parafollicular cells on the outer edges of the follicles of the thyroid
calcitonin
what are the 2 iodine-containing compounds found in the thyroid
T4 - thyroxine
T3 - triiodothyronine
what is the function of the thyroid hormone
increases metabolic rate and body heat
plays a role in BP maintenance, tissue growth, development of skeletal/muscle systems, reproduction
what is the pathology that occurs with hyposecretion of TH (hypothyroidism) in adults
myxedema (lack of iodine)
results in low metabolic rate, chilled, constipation, dry skin, puffy eyes, edema, lethargy, brain fog
what is the pathology that occurs with hyposecretion (hypothyroidism) in children
cretinism
mental retardation, short, disproportionate body, thick tongue/neck
what occurs with hypersecretion of thyroid hormone (hyperthyroidism)
grave’s disease
elevated metabolic rate, sweating, rapid heartbeat, nervousness, weight loss, exophthalomos
where is calcitonin produced
parafollicular cells in the thyroid
when is calcitonin released and inhibited
released in response to high calcium levels
inhibited by low blood calcium levels
negative feedback
what is the function of calcitonin
targets skeleton to inhibit osteoclasts
stimulated calcium uptake and deposition to bone
what hormone is the most important hormone in calcium homeostasis
parathyroid hormone (PTH)
what is the function of PTH
stimulated bone reabsorption
activates osteoclasts
increases calcium and phosphate levels in the blood
where are the parathyroid glands located, what do they secrete
4-8 tiny glands on the posterior thyroid
secrete parathyroid hormone (PTH)
what occurs during hyperparathyroidism
bones soften and deform
elevated blood calcium levels depress the nervous system, leads to kidney stones
what symptoms occur during hypoparathyroidism
increased excitability of muscles due to element imbalances
can lead to tetany (muscle spasms), respiratory imbalances, and possible death
define ricketts
childhood bone deformation due to demineralization
due to calcium, phosphate, and vitamin D deficiency
what is the function of adrenal glands
help body cope with stressful situations
describe the adrenal cortex
outer layer of adrenal gland
glandular tissue that synthesizes and secretes corticosteroids
describe the adrenal medulla
inner portion of adrenal gland
nervous tissue, part of sympathetic nervous system
what layer of the adrenal cortex produces aldosterone
zona glomerulosa
what layer of the adrenal cortex produces cortisol/hydrocortisone
zona fasciculata
what layer of the adrenal cortex produces androgens
zona reticularis
what hormone is the most potent mineralcorticoid
aldosterone
what is the function of mineralcorticoids
regulate electrolytes (sodium, potassium) in the extracellular fluid
what is the function of aldosterone
stimulates sodium reabsoprtion and water retention by kidneys
what is the function of glucocorticoids
maintains constant blood sugar levels
maintains BP by controlling vasoconstrictors
major group released in stress (trauma, infection, illness, temp change, mental stress)
what is the most significant glucocorticoid
cortisol
when is cortisol released
released in response to ACTH
patterns of eating, activity, stress
what is the function of cortisol
promotes gluconeogenesis
promotes rises in blood glucose, fatty acids, amino acids
what is the main gonadocorticoids
androgens
what do androgens contribute to
onset of puberty
appearance of secondary sex characteristics
sex drive in females
describe acinar cells in the pancreas
exocrine cells
produce juice for digestion
describe pancreatic islets/islets of langerhans
contain endovrine cells
contain alpha, beta, gamma cells
what is the function of alpha cells
produce glucagon
what is the function of beta cells
produce insulin
what is the function of gamma cells
secrete somatostatin
when is glucagon released
when blood glucose level is low stimulates glycogenolysis (breakdown of glycogen to glucose)
when is insulin released
blood sugar is too high
stimulates the transfer of glucose from the blood stream into the cells
what is the function of estrogens
maturation of the reproductive organs
apperance of secondary sexual characteristics
thickening of uterus in preparation for pregnancy
wht is the function of progesterone
breast development
menstrual cycle
what is the fucntion of testosterone
initiates maturation of male reproductive organs
appearance of secondary sexual characteristics and sex drive
necessary for sperm production
maintains reproductive organs in their functional state
describe the thymus
located deep to the sternum
large in children, but shrinks with age
essential for T cell development
part of the immune response
what hormones are produced in the kidneys, what are their functions
erythropoetin: stimulates RBC production
renin: returns blood presssure to normal
what is the function of leptin, where is it released
suppressses appetite
released from adipose tissue