Endocrine Flashcards
describe the difference between the exocrine and endocrine systems
exocrine - ducts
endocrine - ductless
Hormones are chemical messengers that regulate body processes like (5)
o Growth and development – physical and mental o Metabolism o Sexual function o Reproduction o Mood stability
pineal gland is responsible for
receive and modulate information about the day vs. night cycle
o secretes melatonin
what does Growth hormone (GH) stimulate
stimulates growth of bone and muscles, determined by genes but maximized by the growth hormones
what does prolactin (PRL) do
part of the anterior pituitary gland, prepares females for breast feeding, level is elevated during pregnancy and breast feeding
what does adrenocorticotropic hormone (ACTH) do
stimulates the synthesis and secretion of adrenocortical hormone
what does thyroid-stimulating hormone (TSH) do
stimulate the synthesis of thyroid hormone
what does follicle-stimulating hormone (FSH) do
affects both males/females. In the females it stimulates the growth of ovarian follicles and ovulation. In males, it stimulates sperm production = spermatogenosis
what does luteinizing hormone (LH) do
for females, it stimulates the development of corpus luteum, the release of oocytes, and production of estrogen and progesterone but mainly progesterone. In males, stimulates the production of testosterone.
anterior pituitary gland secretes what hormones? (6)
- Growth hormone (GH)
- prolactin (PRL)
- adrenocorticotropic hormone (ACTH)
- thyroid-stimulating hormone (TSH)
- follicle-stimulating hormone (FSH)
- luteinizing hormone (LH).
posterior pituitary gland secretes what hormones? (2)
- oxytocin
2. antidiuretic hormone (ADH) or vasopressin
what does oxytocin do?
stimulates the contraction of the pregnant uterus, and milk ejection for breast feeding after childbirth; as opposed to prolactin, it is responsive to the action of breast feeding only
what does ADH/vasopressin do?
increase water reabsorption
what does the hypothalamus do?
regulates the pituitary gland particularly the anterior pituitary gland; the posterior pituitary gland is controlled by brain.
o The master of the master (pituitary gland)
what does the pancreas do?
o Has both exocrine and endocrine function – we focus on endocrine fxn
o Endocrine function- carried out by islets of Langerhans – about 1 million islets of Langerhans
name and describe the 2 main Langerhans cells
o Alpha cells- secrete glucagon, increases BG level
o Beta cells- secrete insulin, decreases BG level
where is the thyroid gland located
Located at the base of the neck below the larynx
- contains several functional units called follicles
what 3 hormones are produced from the thyroid gland follicles
- thyroxine (T4)
- triiodothyronine (T3)
- thyrocalcitonin or calcitonin – lowers the blood calcium level
when TSH stimulates the thyroid gland to secrete T3 and T4, what happens in the body?
- increase the metabolic rate, necessary for fetal growth and development
- increases the body’s responsiveness to catecholamines
where is the parathyroid gland located?
Usually 4 in number; located in the posterior surface of the thyroid gland
what does the parathyroid gland do?
Secretes parathyroid hormone (PTH)- increases serum calcium level
what is within the adrenal glands?
Located in each kidney; each gland has inner (medulla) and outer portion (cortex)
what does the medulla produce and when?
produces epinephrine and norepinephrine during times of stress
describe the outermost region of the cortex
produces mineralocorticoids-
• Principal mineralocorticoid: Aldosterone
describe the middle region of the cortex
produces glucocorticoids-
• Principal glucocorticoid: cortisol – affects metabolism, regulates BG level, affects growth, anti-inflammatory functions, decreases the effect of stress
• If the cortisol level is very low, even a mild stress could be life-threatening
describe the innermost region of the cortex
produces gonadocorticoids (sex hormone)
• Male hormone- Androgen
• Female hormone- Estrogen
• Note: secreted only in minimal amount; hormones from the testes and ovaries mask their effects
when does SIADH occur
happens when there is excessive secretion of ADH from the posterior pituitary gland or other areas outside the mentioned gland
what are the causes of SIADH
most common: carcinoma; these include carcinoma of the tongue, lung, duodenum, pancreas, connective tissues, as swell as leukemia, lymphoma, and Hodgkin’s disease.
o Post-surgery monitor their urinary output for SIADH
when can transient SIADH be seen?
pituitary surgery, use of certain drugs (barbiturates, general anesthetics, vincristine, nicotine, morphine)
what is the normal process for increased extracellular fluid volume (decreased urine output) to balance when the body is dehydrated?
- Elevated serum concentration and/or decrease in extracellular fluid volume/dehydration
- stimulates post pituitary gland to secrete ADH
- ADH increases kidney’s permeability to water = increased water reabsorption (to the plasma)
- decreased urine formation (end result goal: increased extracellular fluid volume).
In SIADH, ADH is secreted unrelated to the main stimuli (even if you’re not dehydrated)?
- Increased ADH = increased water reabsorption in the kidney
- extracellular fluid increases in the blood vessels
- dilution of serum Na (low serum Na = hyponatremia); highly concentrated urine
S/S- related to low Na level- fatigue, weakness, confusion.
what are normal Na levels vs SIADH Na levels
Normal 135-145 mEg/L
!!! Na serum level below 115 mEq/L produces confusion, lethargy, muscle twitching, seizure, coma, and possibly irreversible neurologic damage
Take Home point: key feature of SIADH: water retention, low serum sodium and concentrated urine!
management for SIADH
Treat the underlying cause (hyponatremia in SIADH) = so increasing urine volume and the serum Na level
o Demeclocycline (Declomycin)
o Hypertonic IV
o Diuretic
what is diabetes insipidus (DI)
result in a deficiency of ADH
- 2 types: neurogenic DI; and Nephrogenic DI
describe neurogenic DI
ADH is missing or low secondary to malfunction of the post pituitary gland.
o For example, brain tumor and radiation atrophies the pit gland = neurogenic DI
describe nephrogenic DI
ADH is produced normally but distal tubules and collecting ducts (nephrons) cannot respond to hormone’s signal to reabsorb water.
o Kidneys are insensitive!
why is ADH released into the bloodstream
ADH is released into the bloodstream when needed to cause kidney to reabsorb water.
In DI, water cannot be reabsorbed which leads to what?
In DI, water cannot be reabsorbed - > passed out as urine - > large volume of urine
clinical manifestations of DI
o Change in mentation; insomnia;
o Polydipsia (increased thirst); weight loss from the loss of fluids
o Nocturia (peeing at night); urinary frequency;
o Increased urine output- as much as 4 to 18 liters per day!
treatment of DI
o Treat the underlying cause
o Desmopressin (DDAVP)- IV, subcutaneous, intranasal
• ONLY for neurogenic DI
o Pitressin- intramuscular
• Synthetic antidireutic hormone
o Nephrogenic: thiazide diuretic, prostaglandin inhibitors (NSAIDs)
• If the person is already peeing gallons, why give diuretics, the etiology must be nephrogenic, the pee will lessen
