Pituitary and hypothalamus

Question 1

What houses the pituitary gland

Answer 1

Depression in the sphenoid bone called stella turcica

Question 2

Why are ADH and other hormones by the posterior pituitary are called neurohormones

Answer 2

Cuz they’re produced from the hypothalamus but released by the posterior pituitary and are passed thru the hypothalamohypophyseal tract to the posterior pituitary

Question 3

Oxytocin causes ejection of milk not production of milk true or false

Answer 3

True

Question 4

Mention the 7 hypothalamus regulatory peptides in the hypothalamus pituitary system

Answer 4

●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)

Question 5

What is the Anatomical and Functional Connection Between the Hypothalamus and Pituitary

Answer 5

hypothalamo- hypophyseal portal system and tract)

Question 6

Name the parts of the pituitary gland and functions

Answer 6

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 )

Question 7

Name five functions of the hypothalamus

Answer 7

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

Question 8

How many releasing and how many inhibits hormones does the hypo produce

Answer 8

7 releasing and 2 inhibiting

Question 9

What are tropic hormones

Answer 9

Tropic: hormone that stimulates the secretion of another hormone and often the growth of hormone-secreting gland

Question 10

What synthesized hormones in the posterior pituitary

Answer 10

Supraoptic nucleus
●Paraventricular nucleus

And then the hormones are released by the posterior pituitary

Question 11

Name two functions of ADH or Vasopressin

Answer 11

 water reabsorption by the kidney
●Vasoconstriction
●acts through V1 receptors on the smooth muscle of arteries and arterioles

A

Question 12

How is ADH regulated

Answer 12

ntidiuretic hormone (ADH)
-Vasopressin(VP)
●Regulation
●Plasma Osmotic pressure
●Osmolality ↑ → secretion↑
●Blood volume
●Blood volume↓↓→ secretion↑
    ( Hemorrhage )

Question 13

Name two functions of oxytocin and what causes its secretion

Answer 13

+) milk ejection
●(+)　uterine smooth muscle contraction at birth

Parturition and lactation

Question 14

What controls oxytocin secretion

Answer 14

Physical stimulation of the nipples
●Milk ejection    e.g. suckling
●Neuroendocrine reflex (positive feedback)
●Acute stress
●(-) OTX secretion
●Levels of sex steroids

Question 15

Name five hormones produced by the anterior pituitary

Answer 15

●Growth hormone(GH)
●Prolactin (PRL)
●Thyroid-stimulating hormone (TSH)
●Adrenocoticotropic hormone (ACTH)
●Follicle-stimulating hormone (FSH)
●Luteinizing hormone (LH)
●Melanocyte-stimulating hormone (MSH)

Question 16

What is short loop feedback and long loop feedback in the hypo-pituitary feedback system

Answer 16

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

Question 17

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

Answer 17

True

Question 18

State one Growth hormone and how many amino acids it has

Answer 18

Somatotropin

191 amino acids

Question 19

Mention four effects of growth hormone

Answer 19

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

Question 20

GH’s effects are called diabetogenic, and excess secretion of GH can produce metabolic disturbances ( diabetes ). True or false

Answer 20

True

Question 21

Effect of decreased carbs utilization of these changes results from GH-induced “insulin resistance,” which attenuates insulin’s actions true or false

Answer 21

True

Question 22

Explain how growth promoting effects occur

Answer 22

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 growth

Question 23

Where is circulation iGfs produced and what regulates it secretion

Answer 23

41

➢Most circulating IGFs are produced in the liver.

➢Levels of IGF-1 feed back secretion of GH and GnRH

Question 24

How is growth hormone regulated

Answer 24

Metabolic Factor    p.391  Table11-4
●Sleep-wake cycle dependent rhythm
●Hypothalamus
●GHRH
●GHIH   ( somatostatin )
●IGF-1 secretion in the hypothalamic-pituitary feedback system

Question 25

Name two other factors of growth hormones secretion

Answer 25

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.

Question 26

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

Answer 26

True

Question 27

Name five stimuli and inhibitor growth hormone release

Answer 27

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.

Question 28

Name three abnormalities of growth hem secretion

Answer 28

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

Question 29

Explain acromegaly

Answer 29

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

Question 30

How is the hypothalamus hormone secretion controlled

Answer 30

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)