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Phys: Endocrine > Pituitary Gland > Flashcards

Flashcards in Pituitary Gland Deck (38):

Where is the pituitary gland located?

1. Small oval gland that lies within sella turcica
2. Hangs down inferior to hypothalamus
3. Connected to hypothalamus by the infundibulum


How is the pituitary gland divided?

1. Divided into two lobes based on the function & developmental anatomy
A. Anterior lobe (Adenohypophysis)
B. Posterior lobe (Neurohypophysis)


What hormones does the anterior pituitary gland secrete? What organs/glands do these hormones affect?

1. TSH: thyroid
2. ACTH: adrenal cortex
3. FSH, LH: Testes, ovaries
4. Growth hormone: entire body
5. Prolactin: mammary glands
6. Endorphins: pain receptors in the brain


How is the anterior pituitary gland controlled?

Anterior pituitary gland is controlled by regulatory hormones secreted by the hypothalamus


How do the hormones that control the ant. pit get there?

1. Hormones reach the anterior pituitary via hypothalamo- hypophyseal portal system
A. Takes venous blood carrying regulatory hormones from hypothalamus directly to the anterior pituitary


What hormones are secreted by the posterior pit gland?

1. ADH
2. Oxytocin


Where are ADH and Oxytocin made?

Specialized Neurosecretory cells in the hypothalamus


What hormones control the secretion of ant pit hormones?

1. Thyrotropin Releasing Hormone (TRH)
2. Corticotropin Releasing Hormone (CRH)
A. Growth Hormone Releasing Hormone (GHRH) - Somatotropin
B. Growth Hormone Inhibitory Hormone (GHIH) - Somatastain
4. Gonadotropin Releasing Hormone (GnRH)
5. PIH & PRH
A. Prolactin Inhibitory Hormone (PIH)
B. Prolactin Releasing Hormone (PRH)


How many hormones are released by the ant pit?

6 peptide hormones


What is the function of TSH?

1. Thyrotropin Stimulating Hormone (TSH)
2. Stimulates thyroid gland to secrete thyroxine & triiodothyronine
A. As T4 & T3 increase, TRH & TSH decrease


What is the function of ACTH?

1. Adrenocorticotropic Hormone (ACTH)
2. Stimulates release steroid hormones from adrenal cortex
A. Glucocorticoids & mineralcorticoids
3. Affects metabolism of glucose, proteins, fats
4. Affects immune system & inflammation
5. As cortisol levels increase, CRH & ACTH decrease


What are the main functions of the growth hormones?

1. Stimulates cell growth & replication by accelerating rate of protein synthesis

2. Increases mobilization of fatty acids from adipose tissue & use for energy
3. Controlled by hypothalamus via releasing or inhibiting hormones


What are the direct effects of GH?

1. Salt retention
2. Decreased insulin sensitivity
3. Lipolysis
4. Protein synthesis
5. Epiphysial growth
6. Stimulates IGF-1: insulin like growth hormone 1


What are the indirect effects of GH (through IGF-1)?

1. Insulin-like activity
2. Antilipolytic activity
3. Protein synthesis
4. Epiphysial growth


What is the major controller of GH secretion?

1. Long term state of protein nutrition
A. If protein stores low, GHRH increases, leading to increase GH


What is the general function of LH?

1. Onset ovulation
2. Stimulates corpus luteum
3. Stimulates release of progesterone


What is the general function of FSH?

1. Regulates development of follicle
2. Stimulates release of estrogen


What are the general functions of prolactin?

1. Stimulates mammary gland development
2. Stimulates milk production in mammary glands during pregnancy & post partum


What is the general function of MSH?

1. Darkens skin
2. Endocrine functions unclear


What is the general function of oxytocin?

1. Influences activity of female reproductive system
2. Released at end of gestation
3. Causes uterine contractions
4. Milk ejection reflex during lactation


What are the functions of ADH?

1. Inhibits formation of urine
2. Reduces water excretion


What conditions are caused by growth hormone excess?

1. Acromegaly
2. Gigantism


What is the pathophys of acromegaly?

1. GH excess that begins after epiphyseal closure
2. Pituitary adenoma


What are the sxs of acromegaly?

1. Especially notable in hands, feet, face
2. Many soft tissue organs also become greatly enlarged
A. Tongue, liver, kidneys
3. Increased growth of bone, cartilage and other tissues
A. Increased bone density and width
B. Proliferation of connective and soft tissues
4. Increased CHO catabolism
5. Increased protein synthesis


What is the pathphys of gigantism?

1. GH excess that is present in childhood, before closure of epiphyseal plates of long bones
2. Genetic


What other effects may be present from a pituitary adenoma?

1. Large tumors cause destruction of the pituitary and deficiency of other pituitary hormones and may affect the optic chiasm and vision
A. Bilateral hemianopsia


What are the sxs of gigantism?

1. Increased growth of bone, cartilage and other tissues
A. Remarkable height increases up to 6 inches/yr
Causes enlargement of internal organs
2. Increased CHO catabolism
3. Increased protein synthesis


What is the pathophys of dwarfism?

1. GH deficiency during childhood
2. Features of body develop in appropriate proportion to each other, but rate of development is decreased
3. Genetic


What are the sxs of dwarfism?

1. Short stature
2. Delayed growth
3. Delayed puberty
4. May respond to exogenous GH


What is the general pathophys of diabetes insipidus?

1. Insufficiency ADH causes immediate excretion of large volumes of dilute urine
2. Plasma hyperosmolarity results


What is the neurogenic etiology of DI?

lesion of hypothalamus (thirst center), infundibulum or post pituitary blocks ADH synthesis, transport or release


What is the nephrogenic etiology of DI?

Generally related to disorders or drugs that damage renal tubules


What are the sxs of DI?

1. Intense thirst
2. Craving water
3. Large volume polyuria
A. 3-18 l/day
4. Dehydration


What are the dx studies for DI?

1. No single lab test can confirm DI
2. Gluc
3. BUN, Cr
4. Na, K
A. Hyponatremia
5. Ur Specific Gravity
A. < 1.006
6. 24 hr urine
A. Vol, Gluc, C


What is the treatment for central DI?

1. Desmopressin
A. Treatment of choice
B. Antidiuretic effect
C. Binds to V2 receptor
D. Increases water permeability and
reabsorption in collecting tubules
2. Hydration


What is the treatment for nephrogenic DI?

1. Indomethacin
A. MOA unknown


What are changes in GnRH and FSH controlled by?

circulating levels estrogen and inhibin


What are changes in GnRH and LH controlled by?

circulating estrogens, progestins, & testosterone