hypothalamus and pituitary galnd Flashcards
hypothalamic bundaries
lamina terminalis
interpeduncular fossa
hypothalamic sulcus
tubercinereum
5 parts of the of hypothalamic nuclei
suparoptic nucleus
paraventricular nucleus
ventromedial nuclus
lateral hypothalamic nuclus
suprachiasmatic nucleus
hormone assoc with supraoptic nucleus
antidiuretic hormone (vasopressin)
hormone assoc with paraventricular nucleus
antidiuretic hormone
oxytocin
water conservation
fxn. associated with ventromedial nucleus
satiety
fxns. assoc with lateal hypothalamic nucleus
hunger
thirst
blood pressure
heart rate
fxn. assoc with suprachaismatic nucleus
circadian rhythms
fxn. of the autonomic nervous sytem regulated by hypotahalamus
temp reg.
heart rate
blood pressure
blood osmolarity
food and water intake
emotion
sex drives
cardiovasculature reg. is mediated by
Lateral hypothalamic nucleus = excitatory cardiovascular center
posterior lymphatic nucleus and pre-optic area= decreases arterial pressure, heart rate
respiration is regulated by
Medullary centers that receive info. from the receptors in the hypothalamus responding to changes in {} of CO2, O2, H
Urination and defecation is reg. by
cortex spinal reflexes
food intake is controlled by
ventromedial nucleus = satiety center
lateral hypothalamic area = hunger center
injury in the ventromedial hypothalamic nuclei produces
voracious appetite
rage
obesity
lesions in the lateral hypothalamic area causes
elimination of urge to eat
anorexia
loss of apetite
3 types of receptors in charge of temp. reg.
skin thermoreceptors
preoptic hypothalamic thermoreceptors
anterior hypothalamic
cold and warm receptors
skin thermoreceptors
VOLUNTARY response to blood temperature regulation is done by
cerebral cortex
prevents temperature rise (panting, sweating, vasodilation) –
site of vascular temperature receptors
UNCOSCIOUS RESPONSES
Anterior hypothalamus
prevents temperature loss
glucose oxidation, vasoconstriction, pilo-erection, shivering
Posterior hypothalamus
affected by aspirin, alcohol, interleukins
Hypothalamic thermostat
immune system can be supressed by
stress
ANS/SNS innervates immune tissues
spleen
lymph nodes
Intestinal Peyer’s patches
bone marrow
t/f CNS lesion can affect immune fxns.
true
3 mechanisms of immune system effects on neural function
cytokines = changes neuron firing
interleukin 1 = reset thermostat during fever
activation of lymphocytes = producing neurotransmitters
t/f immune cells don’t have receptors for neurotransmitters
false
3 divisions of the pituitary gland
anterior = adenohypophysis
posterior = neurohypophysis
pituitary stalk
fxns of the ant. pituitary gland
secretion of protein hormones
fxns. of neurohypophysis
extension of hypothalamus
secretion of
ADH
VASOPRESSIN
OXYTOCIN
SITS in the hypophyseal fossa, depression in sella turcica of sphenoid bone
pituitary
tropic hormones are in charge of
Regulating fxn. other hormones, fxn. of endocrine glands
signaling throughout the body
4 tropic hormones secreted by the adenohypophysis
TSH
ACTH
FSH
LH
4 non-tropic peptide hormones secreted by the adenohypophysis
GH growth h.
PRL prolactin
MSH melanocyte stimulating h.
B- endorphin
proteins secreted by neurohypophysis
ADH
OXYTOCIN
Cells of the pars anterior of adenohypophysis
chromophills and chromophobe
Chromophill cells are classified into
- Acidophil cells (somatotrophs, mammotrophs)
- Basophil cells (corticotrophs, thyrotrophs, gonadotrophs)
Chromophobe cells
Contain very few granules in the cytoplasm
Parts tuberalis of adenophypophysis consists of
Chromofill cells : acidophil and basophil cells
t/f Parts intermedia is poorly developed in mammals
true
what is the hypothalamo-hypophyseal portal system?
lies between two capillary beds
neurons form the hypothalamus release their hormones here into the anterior pituitary
Examples of hormones delivered via the hypothalamus-hypopheaseal portal system
CRH
TRH
GnRH
Somatostatin
t/f Pituitary function depends on the hypothalamus
true
What artery connects the adenohypophysis to the hypothalamus?
superior hypophyseal artery
The adenohypophysis is basically
hormone-producing glandular cells
The anterior pituitary is regulated by releasing hormones produced by
neurosecretory cells in the hypothalamus
Hormones synthesized and secreted by the adenohypophysis go into
blood
6 hormones sythesized and secreted by adenohypophysis that go into blood
prolactin
growth hormone (GH)
Melaonocyte stimulating hormone (MSH)
thyroid stimulating hormone (TSH)
adrenocorticotropic hormone (ACTH) follicle-stimulating hormone (FSH) luteinizing hormone (LH)
7 Characteristics of hypothalamic releasing hormones
Secretion in pulses
Act on specific membrane receptors
Transduce signals via second messengers
Stimulate release of stored pituitary hormones
Stimulate synthesis of pituitary hormones
Stimulates hyperplasia and hypertrophy of target cells
Regulates its own receptor
TSH tropic hormone stimulates synthesis and release from
thyroid gland
ACTH tropic hormone stimulates synthesis and release from
adrenal glands
FSH and LH tropic hormone stimulates synthesis and release from
gonads
The anterior pituitary produces six peptide hormones
Prolactin (PRL)
growth hormone (GH),
thyroid stimulating hormone (TSH),
adrenocorticotropic hormone (ACTH),
follicle-stimulating hormone (FSH),
luteinizing hormone (LH)
prolactin fxn.
Mammary gland development & milk production
growth hormone acts on
Liver & Many tissues and organs of the body
is prolactin a trphic or non-trophic hormone?
non-trophic
regulates
fat metabolism and reproduction in birds
delays metamorphosis in amphibians
regulates salt and water balance in freshwater fishes
prolactin h.
Regulates the activity of pigment-containing cells in the skin of some fishes, amphibians, and reptiles.
in mammals acts on neurons in the brain, inhibiting hunger
Melanocyte-stimulating hormone (MSH)
Bind to receptors in the brain and dull the perception of pain.
b-endorphin
magnocellular neurons paraventricular and supraoptic nuclei secrete
oxytocin and vasopressin directly into capillaries in the posterior lobe
induces contraction of the smooth muscle of the uterus during childbirth and causes mammary glands to eject milk during nursing.
exhibits positive feedback in both cases
oxytocin
promotes retention of water by the kidneys, decreasing urine volume
regulate osmolarity of the blood via negative feedback.
Secretion is regulated by water/salt balance.
Antidiuretic hormone (ADH) or Vasopressin
9 amino acid peptide that is synthesized in hypothalamic neurons (PVN and SON) and transported down axons directly into the posterior pituitary for secretion into blood
oxytocin
t/f oxytocin is also secreted in the ovaries and testes
true
t/f oxytocin acting within the brain plays a major role in establishing maternal behavior.
true
t/f oxytocin is involved in facilitating sperm transport within the male reproductive system and perhaps also in the female, due to its presence in seminal fluid and sexual behavior
true
The most important stimulus for release of hypothalamic oxytocin is initiated by
stimulation of the nipples or teats via spinal refelex arc
acute stress or catecholamines inhibit
oxytocin release
Both the production of oxytocin and response to oxytocin are modulated by circulating levels of
sex steroids
most important physiological effect of ADH
conserve fluid in the body by reducing urine output.
In the absence of ADH
the kidney tubules are virtually impermeable to water, and it flows out as urine.
ADH release is increased by following stimuli:
Pain, trauma(impulses from the periphery to CNS) Loud noise, unpleasant sight, emotional stress, fear, anxiety.
ADH release is inhibited by
Cold exposure, conditioned reflex diuresis, suggestion of water drinking under hypnosis.
Drugs that increases ADH
Anesthetic and tranquilizers like barbiturates, morphine, ether
Nicotine, Angiotensin II, Beta adrenergic drugs
Acetyl choline & cholinergic drug (carbachol, methacholine)
Drugs that decrease ADH
Alcohol
Phenytoin
Anticholinergic drugs
Adrenergic drugs
what specifically ADH stimulates in kideney tubules for H2O reabsorption?
insertion of “water channels” or aquaporins into the membranes of kidney tubules.
aquaporins transoprt
solute-free water through tubular cells and back into blood, decreasing plasma osmolarity increasing osmolarity of urine
ADH Promotes
REABSORPTION OF WATER BACK INTO CIRCULATION
high concentrations of ADH cause widespread constriction of arterioles which leadING TO
increased arterial pressure
WHAT CONTROLS ADH?
Plasma osmolarity, or the concentration of solutes in blood
osmoreceptors
Neurons in the hypothalamus that sense osmolarity stimulating secretion of ADH
When osmolarity increases above the threshold, osmoreceptors are activated and
secrete ADH
2 factors that regulate ADH release
changes in blood pressure and blood volume, through stretch receptors located in the heart and large blood vessels
Osmolarity increase above the threshold
diabetes insipidus can be caused by 2 mechanisms
hypothalamic
nephrogenic
Explain the hypothalamic cause of diabates insipidus
from a deficiency in secretion of ADH from the posterior pituitary. Causes of this disease include head trauma, and infections or tumors involving the hypothalamus.
Explain the nephrogenic cause of diabates insipidus
kidney is unable to respond to ADH. Most commonly, this results from some type of renal disease, but mutations in the ADH receptor gene or in the gene encoding aquaporin-2 have also been demonstrated in affected humans.
Effects of alcohol on ADH release
enters the blood-causes the pituitary gland to block the synthesis of ADH. kidneys send water directly to the bladder instead of reabsorbing it into the body.
decreases as the alcohol in the bloodstream decreases, but the after effect, help to create a hangover
diuretic effect
characteristics of the pineal gland
Attached to the thalamus
Innervation comes from postganglionic sympathetic fibers
Secretes melatonin
May help control circadian rhythms
Inhibits gonadotropin secretion (FSH, LH) in children
regulates the onset of puberty and allows children to sleep more
pineal gland
