hypothalamus and pituitary galnd Flashcards by Veronica Arbona

hypothalamic bundaries

lamina terminalis
interpeduncular fossa
hypothalamic sulcus
tubercinereum

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5 parts of the of hypothalamic nuclei

suparoptic nucleus
paraventricular nucleus
ventromedial nuclus
lateral hypothalamic nuclus
suprachiasmatic nucleus

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hormone assoc with supraoptic nucleus

antidiuretic hormone (vasopressin)

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hormone assoc with paraventricular nucleus

antidiuretic hormone
oxytocin
water conservation

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fxn. associated with ventromedial nucleus

satiety

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fxns. assoc with lateal hypothalamic nucleus

hunger
thirst
blood pressure
heart rate

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fxn. assoc with suprachaismatic nucleus

circadian rhythms

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fxn. of the autonomic nervous sytem regulated by hypotahalamus

temp reg.
heart rate
blood pressure
blood osmolarity
food and water intake
emotion
sex drives

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cardiovasculature reg. is mediated by

Lateral hypothalamic nucleus = excitatory cardiovascular center
posterior lymphatic nucleus and pre-optic area= decreases arterial pressure, heart rate

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respiration is regulated by

Medullary centers that receive info. from the receptors in the hypothalamus responding to changes in {} of CO2, O2, H

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Urination and defecation is reg. by

cortex spinal reflexes

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food intake is controlled by

ventromedial nucleus = satiety center
lateral hypothalamic area = hunger center

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injury in the ventromedial hypothalamic nuclei produces

voracious appetite
rage
obesity

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lesions in the lateral hypothalamic area causes

elimination of urge to eat
anorexia
loss of apetite

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3 types of receptors in charge of temp. reg.

skin thermoreceptors
preoptic hypothalamic thermoreceptors
anterior hypothalamic

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cold and warm receptors

skin thermoreceptors

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VOLUNTARY response to blood temperature regulation is done by

cerebral cortex

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prevents temperature rise (panting, sweating, vasodilation) –
site of vascular temperature receptors
UNCOSCIOUS RESPONSES

Anterior hypothalamus

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prevents temperature loss
glucose oxidation, vasoconstriction, pilo-erection, shivering

Posterior hypothalamus

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affected by aspirin, alcohol, interleukins

Hypothalamic thermostat

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immune system can be supressed by

stress

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ANS/SNS innervates immune tissues

spleen
lymph nodes
Intestinal Peyer’s patches
bone marrow

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t/f CNS lesion can affect immune fxns.

true

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3 mechanisms of immune system effects on neural function

cytokines = changes neuron firing
interleukin 1 = reset thermostat during fever
activation of lymphocytes = producing neurotransmitters

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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

hypothalamus and pituitary galnd Flashcards

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