Pituitary and hypothalamus Flashcards
What houses the pituitary gland
Depression in the sphenoid bone called stella turcica
Why are ADH and other hormones by the posterior pituitary are called neurohormones
Cuz they’re produced from the hypothalamus but released by the posterior pituitary and are passed thru the hypothalamohypophyseal tract to the posterior pituitary
Oxytocin causes ejection of milk not production of milk true or false
True
Mention the 7 hypothalamus regulatory peptides in the hypothalamus pituitary system
●Thyrotropin-releasing hormone (TRH)
●Gonadotropin-releasing hormone (GnRH)
●Corticotropin-releasing hormone (CRH)
●Growth hormone releasing hormone (GHRH)
●Prolactin releasing hormone (PRH)
●Growth hormone release-inhibiting hormone (GHRIH, somatostatin)
●Prolactin release-inhibiting hormone (PIH, Dopamine)
●Melanophore-stimulating hormone releasing factor (MRF)
●Melanophore-stimulating hormone release-inhibiting factor (MIF)
What is the Anatomical and Functional Connection Between the Hypothalamus and Pituitary
hypothalamo- hypophyseal portal system and tract)
Name the parts of the pituitary gland and functions
Pituitary ( Hypophysis )
●Anterior Pituitary
( Adenohypophysis ) adenohypophysis; pars distalis )
●true endocrine tissue
●secretes classic hormones : GH, PRL, TSH, FSH/LH,ACTH
● Posterior pituitary
(neurohypophysis; pars nervosa)
●neural tissue
●sectetes neurohormones
●Posterior Pituitary
( Neurohypophysis )
Name five functions of the hypothalamus
Contains neural centers for hunger, thirst,
and body temperature.
➢Contributes to the regulation of sleep, wakefulness,
emotions, ect
➢Stimulates hormonal release from anterior pituitary.
➢Produces antidiuretic hormone (ADH) and oxytocin.
Coordinates sympathetic and parasympathetic reflexes
➢Secretes releasing and inhibiting hormones to regulate release of hormones from the anterior pituitary
➢Function as tropic＊ hormones to either stimulate or
inhibit release of anterior pituitary hormones
How many releasing and how many inhibits hormones does the hypo produce
7 releasing and 2 inhibiting
What are tropic hormones
Tropic: hormone that stimulates the secretion of another hormone and often the growth of hormone-secreting gland
What synthesized hormones in the posterior pituitary
Supraoptic nucleus
●Paraventricular nucleus
And then the hormones are released by the posterior pituitary
Name two functions of ADH or Vasopressin
water reabsorption by the kidney
●Vasoconstriction
●acts through V1 receptors on the smooth muscle of arteries and arterioles
A
How is ADH regulated
ntidiuretic hormone (ADH)
-Vasopressin(VP)
●Regulation
●Plasma Osmotic pressure
●Osmolality ↑ → secretion↑
●Blood volume
●Blood volume↓↓→ secretion↑
( Hemorrhage )Name two functions of oxytocin and what causes its secretion
+) milk ejection
●(+) uterine smooth muscle contraction at birth
Parturition and lactation
What controls oxytocin secretion
Physical stimulation of the nipples ●Milk ejection e.g. suckling ●Neuroendocrine reflex (positive feedback) ●Acute stress ●(-) OTX secretion ●Levels of sex steroids
Name five hormones produced by the anterior pituitary
●Growth hormone(GH) ●Prolactin (PRL) ●Thyroid-stimulating hormone (TSH) ●Adrenocoticotropic hormone (ACTH) ●Follicle-stimulating hormone (FSH) ●Luteinizing hormone (LH) ●Melanocyte-stimulating hormone (MSH)
What is short loop feedback and long loop feedback in the hypo-pituitary feedback system
Long loop feedback refers to the hormone that was relerased from the peripheral endocrine glands inhibiting pituitary and/or hypothalamic secretion of releasing hormones. inhibition of anterior pituitary and/or hypothalamus
by hormone secreted by third endocrine gland example is cortisol production
Short loop feedback generally refers to a pituitary hormone providing negative feedback to the hypothalamus, inhibiting secretion of the releasing hormone. Or influence of hypothalamus by the anterior pituitary hormone for example, growth hormone releasing hormone (GHRH) from the hypothalamus is inhibited by growth hormone (GH) that has been released from the pituitar
Growth hormone, in contrast to other hormones, does not function through a target gland but exerts its effects directly on all or almost all tissues of the body. True or false
True
State one Growth hormone and how many amino acids it has
Somatotropin
191 amino acids
Mention four effects of growth hormone
Growth hormone
●The primary physiological effects of GH are to simulate bone growth and protein anabolism
●Has little or no effect on fetal growth (embryo and fetus)
●Most important for postnatal growth
●Major growth promoting effect via stimulation of cell division in many target tissues
●e.g. promotes bone lengthening by stimulating maturation and cell division of the chondrocytes in epiphyseal plate
Metabolic effects-Promote Protein deposition
●protein anabolism (protein synthesis )
●Amino acids transport through the cell membranes
● RNA translation
● DNA transcription
● Catabolism of protein and Amino acids
●Enhance Fat Utilization for Energy: mobilization of fatty acids from adipose tissue
free fatty acids in the blood
● use of the fatty acids for energy
●Decrease Carbohydrate Utilization: Glucose uptake in tissues
●Glucose production by the liver
●Insulin secretion
In conclusion: functions of growth hormone are ●Metabolic Effects
●Promote Protein deposition
●Enhance Fat Utilization for Energy
●Decrease Carbohydrate Utilization
●Growth-promoting effects (bone, muscle,et al)
●Effects on Immunology system and Myocardium, ect
GH’s effects are called diabetogenic, and excess secretion of GH can produce metabolic disturbances ( diabetes ). True or false
True
Effect of decreased carbs utilization of these changes results from GH-induced “insulin resistance,” which attenuates insulin’s actions true or false
True
Explain how growth promoting effects occur
Indirect action (bone, muscle, et al)
●Somatomedin (direct)
●Insulin-like growth factor I
( IGF-I ) postnatal growth
●Insulin-like growth factor II
( IGF-II )
induce the fetal growthWhere is circulation iGfs produced and what regulates it secretion
41
➢Most circulating IGFs are produced in the liver.
➢Levels of IGF-1 feed back secretion of GH and GnRH
How is growth hormone regulated
Metabolic Factor p.391 Table11-4 ●Sleep-wake cycle dependent rhythm ●Hypothalamus ●GHRH ●GHIH ( somatostatin ) ●IGF-1 secretion in the hypothalamic-pituitary feedback system
Name two other factors of growth hormones secretion
Growth hormone and insulin are important anabolic hormones in humans, although growth hormone has many insulin-antagonistic effects.
●Normal Changes in the Growth Hormone Axis with Aging
●Growth hormone is released as hunger spikes during the day and during sleep.
Hypothyroid children (cretins) also become dwarfs. The thyroid hormones are necessary or permissive for normal growth and development. Cretins are mentally retarded, hypothyroid dwarfs. True or false
True
Name five stimuli and inhibitor growth hormone release
deep sleep, ➢hypoglycemia, ➢fasting, ➢exercise, ➢elevation of certain amino acids, especially arginine, ➢stress, ➢estrogens, ➢high levels of insulin. ●Inhibitors of GH release are: ➢hyperglycemia, ➢obesity, ➢increased glucocorticoids, ➢late pregnancy.
Name three abnormalities of growth hem secretion
Dwarfism ●GH ↓( in childhood ) ●Gigantism ●GH ↑ ( in childhood ) ●Acromegaly ●GH ↑ ( in adulthood )
GH excess before the long bone epiphyses have closed, results in gigantism. The arms and legs are long, and the patients are tall.
GH excess after the long bone epiphyses have closed, GH stimulates both soft-tissue and skeletal growth. In adults, only bones in the cranium, the face, and the hands and feet respond the GH excess
Explain acromegaly
53
Acromegaly
Epiphyseal
growth
plate
1.GH excess after the long bone epiphyses have closed (It means the epiphyseal growth plate is disappeared), results in Acromegaly.
2.In adults only bones in the cranium, the face, and the hands and feet respond the GH excess.
3.Acromegaly often develops around the age of 30 years in both females and males.
Diagnosis- IGF-1 measurement: After you’ve fasted overnight, your doctor will take a blood sample to measure the IGF-1 level in your blood. An elevated IGF-1 level suggests acromegaly.
Growth hormone suppression test:This is the best method for confirming an acromegaly diagnosis. During this test, your GH blood level is measured both before and after you drink a preparation of sugar (glucose). In people who don’t have acromegaly, it’ll reduce if they have, it’ll still be increased.
Imaging:Your doctor may recommend an imaging test, such as magnetic resonance imaging (MRI), to help pinpoint the location and size of a tumor on your pituitary gland. If no pituitary tumors are seen, your doctor may order other imaging tests to look for nonpituitary tumors.
Treatment: Doctors can remove most pituitary tumors using a method called transsphenoidal surgery. During this procedure, your surgeon works through your nose to remove the tumor from your pituitary gland. Or you can be treated with drugs such as Drugs that reduce growth hormone production (somatostatin analogues). In the body, a brain hormone called somatostatin works against (inhibits) GH production. The drugs octreotide (Sandostatin) and lanreotide (Somatuline Depot) are man-made (synthetic) versions of somatostatin. Taking one of these drugs signals the pituitary gland to produce less GH, and may even reduce the size of a pituitary tumor. Typically, these drugs are injected into the muscles of your buttocks (gluteal muscles) once a month by a health care professional.
Drugs to lower hormone levels (dopamine agonists). The oral medications cabergoline and bromocriptine (Parlodel) may help lower levels of GH and IGF-1 in some people. These drugs may also help decrease tumor size and drugs that block the action of the growth hormone
How is the hypothalamus hormone secretion controlled
Nervous regulation
●Hormonal regulation:
●Long-loop feedback
●Short-loop feedback
●Ultrashort-loop feedback
Example: Typical sequence of events leading from the thyrotropin hormone (hormone 1 which is produced by the hypothalamus)which controls the secretion of hormone 2 (thyroid stimulating hormone by anterior pituitary)when it’s plasma concentration is high which
in turn affects the secretion of a hormone (thyroid hormones)
by a third endocrine gland(thyroid gland) ( hormone 3) which also occurs when hormone 2 plasma levels increase
Or secretion of corticotropin releasing hormone by hypo causes secretion of adrenocorticotropic hormone by anterior pituitary which causes secretion of glucocorticoids from adrenal cortex
Or secretion of gonadotropin releasing hormone by hypo which causes secretion of FSH from the anterior pituitary which causes secretion of inhibin and estrogen from the testes(inhibin) and ovary(inhibin and estrogen)
