Chapter 5 - Oxytocin & ADH Flashcards
What are another names for antidiuretic hormone?
Vasopressin, argipressin, arginine vasopressin
Oxytocin and antidiuretic hormone are released from where?
Posterior pituitary gland
What is another term for the posterior pituitary gland?
Neurohypophysis
What is the function of the neurohypophysis?
Store and secrete neurohormones in response to nerve signals from the brain
The posterior pituitary gland is an extension of what brain feature?
Hypothalamus
Where is oxytocin produced?
Supraoptic nucleus
Paraventricular nuclei of the hypothalamus
Where is oxytocin stored?
Posterior pituitary gland
What is the target cell for vasopressin?
Kidney tubules
What is the target cell for oxytocin?
Mammary glands, uterine muscles
What are the primary functions of oxytocin?
Stimulate milk release, stimulate parturition, stimulate uterine shrinkage after birth
How does oxytocin directly stimulate milk release?
By stimulating the myoepithelial cells in mammary glands
What hormone functions in stimulating milk production in lobular and alveolar ducts?
Luteotropic hormone (prolactin)
What are the secondary functions of oxytocin?
Increase renal reabsorption of water Increase immune response Stimulate vasoconstriction (therefore increased blood pressure) Increase digestion Decrease memory
In what specific part of the uterus does oxytocin stimulate smooth muscle contraction?
Myometrium
What is the Ferguson reflex?
Reflex from uterus to higher brain centers back down to stimulate uterine contractions
What controls the secretion of oxytocin?
Neurological impulses
The “urge to push” is associated with what neurological impulse?
Baby pressing on the Ferguson Plexus of nerves
Current research is suggesting that oxytocin could play a therapeutic role in what common child disorder and in what way?
Autism (could lead to improved social functioning)
In what ways can oxytocin act as more than just a “love” hormone?
Improve workplace bonding, reduce stress and anxiety
What is the negative social aspect that some studies have revealed about oxytocin?
Could cause people to shun others leading to group favoritism and prejudice
Oxytocin appears to inhibit the appetite for what kinds of food?
Sugar and carbohydrates
What is the function of agouti-related protein neurons?
Stimulate food intake (enhance appetite)
What effect do agouti-related protein neurons have on oxytocin?
Inhibits the paraventricular-oxytocin neurons
In what condition do patients have a reduction in the oxytocin receptor gene?
Prader-Willi syndrome
What happened to animals in a study when they were engineered to have the oxytocin receptor knocked out?
They consumed large amounts of sweet foods
Oxytocin is implicated in the modulation of reward which can be associated with what disorder?
Bulimia nervosa
What are the functions of the amygdala?
Face perception and emotion processing
Oxytocin actively works with what part of the limbic system?
Amygdala
Oxytocin has a profound effect on what kind of behavior?
Social
Epigenetic modification of the oxytocin receptor gene can lead to what social effect?
Influence on the perception of anger and fear in the human brain
Through what ways can oxytocin promote social and affiliative behaviors?
Reduced threat reactivity
Increased sensitivity to social salience
Where is ADH synthesized?
Supraoptic nuclei of the hypothalamus
What is the primary function of vasopressin?
Regulate body’s retention of water
What are the secondary functions of ADH?
Increase blood pressure through vasoconstriction
Increase the immune system
Increase STH, ACTH, and prostaglandin secretions
Increase metabolism
How is antidiuretic hormone secretion regulated?
Neurological impulse down the hypothalamic hypophyseal tract (HHT)
What physiological aspects are maintained by antidiuretic hormone?
Blood pressure and blood volume
How does the body obtain water?
Absorbing it from the digestive tract
Maintenance of water balance by ADH is linked to the balance of what substances?
Sodium and potassium
What effect does increase in sodium in the bloodstream have on antidiuretic hormone?
Thirst will develop, ADH will increase and cause kidneys to decrease urine output
Recent research has shown that vasopressin antagonism may be a potential use for what neurological condition?
Patients after acute stroke to limit cerebral edema
What is central diabetes insipidus?
Decreased output of ADH —> excessive urine output (polyuria) —> excessive thirst
What can cause central diabetes insipidus?
Insufficient release of ADH by the hypothalamus or by the pituitary gland into the bloodstream (other: surgery, trauma, aneurism)
What hormone is increased as a result of compensation for decreased ADH during central diabetes insipidus?
Increased aldosterone
Why do we see increased aldosterone in central diabetes insipidus?
Blood pressure drops and body tries to restore it to normal
What kind of specific receptors in the hypothalamus trigger the release of ADH?
Osmoreceptors
What are the physical characteristics of central diabetes insipidus?
Polyuria, dilute urine, hypotension, increased plasma concentration
Why do we see dilute urine in patients with central diabetes insipidus?
Excess urine output means overall decreased urine concentration
Why do we see hypotension in patients with central diabetes insipidus?
Due to decreased plasma volume
What compensation for central diabetes insipidus can attempt to bring blood pressure back to normal?
Increased aldosterone
Increased renal reabsorption of sodium (conservation)
Excretion of hydrogen and potassium ions
Where is aldosterone produced?
Adrenal cortex
What is the function of aldosterone?
Act on the distal tubules and collecting ducts of the kidney to increase reabsorption of water and electrolytes and also increase blood volume and blood pressure
What causes nephrogenic diabetes insipidus?
Decreased sensitivity to ADH and increased secretion of ADH
What are the physical characteristics of nephrogenic diabetes insipidus?
Polyuria, dilute urine (decreased urine concentration), hypotension (decreased plasma volume), increased plasma concentration
What is the difference between central diabetes insipidus and nephrogenic diabetes insipidus?
Central diabetes insipidus = decreased output of ADH
Nephrogenic diabetes insipidus = increased output of ADH but kidneys fail to respond to it (insensitivity)
What is the result of the ADH insensitivity of the kidneys in nephrogenic diabetes insipidus?
Inability to concentrate urine
What can cause nephrogenic diabetes insipidus?
Drugs (lithium), hereditary (carried on the X chromosome)
High levels of what substance can block the action of ADH?
Calcium
Low levels of what substance can block the action of ADH?
Potassium
What other conditions are other factors to consider with nephrogenic diabetes insipidus?
Polycystic kidneys, spongy kidneys, sickle cell anemia
What condition is characterized by large amounts of ADH release leading to difficulty ridding the body of excess water?
Inappropriate antidiuretic hormone secretion (SIADH)
What is hyponatremia, and what condition is it seen with?
Abnormally low levels of sodium; inappropriate antidiuretic hormone secretion (SIADH)
What conditions can result in fluid overload in patients?
Strokes, head trauma, brain tumors (cerebral edema)
