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Clinical Chemistry 2 > 1. Hypothalamic and Pituitary Function > Flashcards

1. Hypothalamic and Pituitary Function Flashcards

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1
Q

The endocrine system uses chemical messengers called ________ for ________ distance communication between endocrine organs and their target cells

A

Uses chemical messengers called hormones for long distance communication

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2
Q

What are the two kinds of endocrine organs and what is the difference

A

Primary endocrine organs: primary function is the secretion of hormones

Secondary endocrine organs: have a non-endocrine function

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3
Q

What are the two primary endocrine organs?

A

Hypothalamus and pituitary gland

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4
Q

What are the 4 parts of the endocrine system?

A
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5
Q

What does the hypothalamus and the posterior pituitary do?

A

Hypothalamus synthesizes and secretes antidiuretic hormone (ADH) and oxytocin. Both sent and stored in posterior pituitary and released when needed

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6
Q

What does the hypothalamus and the anterior pituitary do?

A

Hypothalamus exerts control of anterior pituitary by secreting tropic hormones which regulate the secretion of other hormones by either stimulating or inhibiting their secretion

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7
Q

What is the difference between tropic and non-tropic hormones?

A

Tropic hormones function by stimulating the endocrine gland to facilitate the release of another hormone. For example, the thyroid-stimulating hormone stimulates the release of thyroxin from the thyroid gland.

On the other hand, non-tropic hormones (thyroxin) act straight on the target organ for the specified function

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8
Q

What organ is the head of the endocrine system?

A

The hypothalamus

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9
Q

What is the hypothalamus’ function?

A

To release hormones to control and stimulate the pituitary gland

And coordinates messages of the endocrine and nervous systems

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10
Q

The hypothalamus and pituitary gland are connected via ________

A

System of blood vessels called portal system

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11
Q

Hormones produced in _________ travel through the _________ and stimulate the __________

A

Hormones produced in the hypothalamus travel through the portal system and stimulate the pituitary gland

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12
Q

Which gland is considered the “master gland” because it can regulate other glands?

A

Pituitary gland

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13
Q

What is the difference between the posterior and anterior lobes of the pituitary gland?

A

Posterior lobe: extension of neurons from hypothalamus

Anterior lobe: non-neural tissues which unlike the posterior pituitary has no direct nervous connection with hypothalamus. Hypothalamus exerts control of anterior pituitary by secreting tropic hormones

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14
Q

Tropic hormones are released by?

A

Most tropic hormones are produced and secreted by the anterior pituitary. The hypothalamus secretes tropic hormones that target the anterior pituitary

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15
Q

What are the distinguishing features of pituitary function (4)?

A
  1. Feedback loops
  2. Pulsatile secretions (hormones secreted in burst-like or episodic manner rather than constantly)
  3. Circadian rhythm
  4. Environmental or external modification of its performance
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16
Q

How many hormones does the hypothalamus release? How many tropic hormones and how many are non-tropic hormones?

A

2 non-tropic hormones

7 tropic hormones

9 hormones

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17
Q

What are the 2 non tropic hormones that the hypothalamus secretes?

A
  1. Oxytocin

2. Anti-diuretic hormone (ADH/vasopressin)

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18
Q

What is another name for vasopressin?

A

Anti diuretic hormone (ADH)

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19
Q

What are the 7 tropic hormones released by the hypothalamus?

A
  1. Prolactin releasing hormone (PRH)
  2. Prolactin inhibiting hormone (Dopamine)
  3. Thyrotropon releasing hormone (TRH)
  4. Growth hormone releasing hormone (GHRH)
  5. Growth hormone inhibiting hormone (somatostatin)
  6. Corticotropin releasing hormone (CRH)
  7. Gonadaotropin releasing hormone (GNRH)
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20
Q

PRH stimulates anterior pituitary to secrete what hormone?

A

Prolactin

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21
Q

What is another name for dopamine?

A

Prolactin inhibiting hormone

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22
Q

TRH stimulates anterior pituitary to secrete what hormone?

A

Thyroid stimulating hormone (TSH)

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23
Q

GHRH stimulates anterior pituitary to secrete what hormone?

A

Growth hormone

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24
Q

What is another name for somatostatin?

A

Growth hormone inhibiting hormone (GHIH)

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25
Q

What does somatostatin inhibit?

A

Inhibits the anterior pituitary gland’s secretion of growth hormone (GH) and thyroid stimulating hormone (TSH)

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26
Q

CRH stimulates anterior pituitary to secrete what hormone?

A

Adrenocorticotropic hormone (ACTH)

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27
Q

GNRH stimulates anterior pituitary to secrete what hormones (2)v

A

Follicle stimulating hormone (FSH) and Luteinizing hormone (LH)

28
Q

Which hormones are released by the hypothalamus and stored in the posterior pituitary (posterior hormones)?

A

Oxytocin and ADH (vasopressin)

29
Q

What does oxytocin target, when is it secreted and what is its function?

A

Oxytocin targets Uterine smooth muscle and Mammary gland

Toward end of pregnancy, synthesis of oxytocin receptors in uterus increase, so the smooth muscles in uterus become more sensitive to its effects.

When fetal development is complete, the hormone stimulates uterine contractions and dilation of cervix. Continually released throughout childbirth through positive feedback mechanism

Breastfeeding - oxytocin makes the milk that is already in the breast flow for the current feed, and helps the baby to get the milk easily (stimulates let down of milk because of smooth muscle contraction).

30
Q

What does ADH target, when is it secreted and what is its function?

A

The target cells of ADH are located in the tubular cells of the kidneys. Released when there is high blood osmolarity, which can occur due to dehydration or following very salty meal.

Its effect is to increase epithelial permeability to water, allowing increased water reabsorption. The more water reabsorbed from the filtrate, the greater the amount of water that is returned to the blood and the less that is excreted in the urine (concentrate urine to conserve water)

31
Q

What are the anterior pituitary hormones (6)?

A
  1. Growth hormone (GH)
  2. Thyroid stimulating hormone (TSH)
  3. Adrenocortciotropic hormone (ACTH)
  4. Follicle stimulating hormone (FSH)
  5. Luteinizing hormone (LH)
  6. Prolactin
32
Q

What is the primary function of growth hormone (2)?

A

Protein synthesis and tissue building

33
Q

What are the 3 effects of growth hormone?

A
  1. Stimulate adipose tissue cells to break down stored fat, fueling growth effects
  2. Growth effects: increases uptake of amino acids from blood and enhances cell proliferation and reduces apoptosis. Targets: bone cells, muscle cells, nervous system cells, immune system cells
  3. GH stimulates liver to break down glycogen into glucose, fueling growth effects. Liver also releases insulin growth factor 1 (IGF-1) that further stimulates growth effects
34
Q

What is IGF-1?

A

Insulin growth factor 1, released by kidney after stimulation by GH, further stimulates growth effects

35
Q

What tests are done to measure growth hormone (2)?

A

The growth hormone suppression test and growth hormone stimulation test

36
Q

What is the methodology of the growth hormone suppression test?

A

Oral glucose tolerance test (OGTT) (also used to test for diabates): Overnight fast, drink 100g glucose load, and blood samples are usually collected for 1 to 2 hours after you finish drinking the glucose solution to measure GH. This is to measure if anterior pituitary gland releasing too much GH. The drink should normally cause blood glucose levels to rise which should make GH levels go lower.

37
Q

What is the methodology of the growth hormone stimulation test?

A

The growth hormone (GH) stimulation test measures the ability of the body to produce GH. Overnight fast (10-12 hrs), blood sample taken. Amino acid arginine administered in vein to raise GH levels. Additional blood samples are drawn over the next few hours.

38
Q

What is acromegaly? What does it cause?

A

Disorder that occurs when too much GH is produced. Most cases due to a pituitary tumor. In adults, too much of this hormone causes bones, cartilage, body organs, and other tissues to increase in size. Common changes in appearance include enlarged or swollen nose, ears, hands, and feet, mandible, skill.

39
Q

What is the similarity and difference between acromegaly and gigantism?

A

Both due to hypersecretion of GH.

Gigantism occurs when growth hormone hypersecretion occurs before the fusion of the long bone epiphysis (growth plate hasnt hardened or fused) and is characterized by tall stature (in children). Acromegaly occurs when GH hypersecretion occurs after the fusion of the epiphysis leading to large extremities and characteristic facies (in adults)

40
Q

Growth hormone deficiency is also called what?

A

Pituitary dwarfishm

41
Q

Growth hormone deficiency can occur in children only, adults only, or both?

A

Both

42
Q

If growth hormone deficiency occurs in children, its due to _________. If it occurs in adults, its due to _________

A

Children: genetic or tumors
Adults: result of structural/functional pituitary abnormalities (can be tumor)

43
Q

What are the various genetic defects associated with pituitary dwarfism (4)?

A
  1. Recessive mutation in GHRH gene, failure to secrete GH
  2. Loss of GH gene
  3. GH insensitivity
  4. Structural lesions (tumor) of pituitary or hypothalamus
44
Q

What is the function of TSH? When is it secreted and what does it target

A

Thyroid stimulating hormone (TSH) released by anterior pituitary in response to thyrotropin releasing hormone (TRH) from hypothalamus. TSH triggers release of thyroid hormones by thyroid gland

45
Q

What is another name for TSH?

A

Thyrotropin

46
Q

What is the function of ACTH? When is it secreted and what does it target?

A

Adrenocorticotropic hormone (ACTH) released by anterior pituitary in response to corticotropin releasing hormone (CRH) by the hypothalamus. Targets the adrenal cortex to secrete corticosteriod hormones (cortisol)

47
Q

What is another word for ACTH?

A

Corticotropin

48
Q

What is the function of FSH and LH? When is it secreted and what does it target?

A 
Targets gonads (testes, ovaries)
Released from anterior pituitary in response to gonadotrophin releasing hormone (GNRH) from hypothalamus

Luthenizing hormone (LH) stimulates secretion of sex steroids from the gonads. Women: estrogens and progesterone. Men: testosterone

Follicle stimulating hormone (FSH) stimulates the maturation of ovarian follicles. FSH is also critical for sperm production. It supports the function of Sertoli cells, which in turn support many aspects of sperm cell maturation.

49
Q

What is the function of prolactin? When is it secreted and what does it target?

A

Prolactin (PRL) secreted by anterior pituitary in response to PRH from the hypothalamus.

Targets breasts. During pregnancy, it contributes to development of mammary glands, and after birth, it stimulates mammary glands to produce breast milk (milk production).

(However, effects of prolactin depend heavily on effects of estrogens, progesterone, and oxytocin).

50
Q

What is the difference between oxytocin and prolactin?

A

Oxytocin- stored and released from the posterior pituitary gland, triggers uterine contractions during childbirth (positive feedback) and also stimulates let down of milk after birth

Prolactin- released by anterior pituitary in response to PRH from hypothalamus, promotes lactation (milk production) and not let down

51
Q

What is prolactinoma?

A

A pituitary tumor that directly secretes prolactin, Overproduction of prolactin

52
Q

What is the clinical presentation of prolactinoma in premenopausal women and men?

A

Premenopausal women: menstrual irregularity/amenorrhea (no periods), infertility, galactorrhea (milky breast discharge unrelated to breast feeding)

Men: high prolactin levels can cause galactorrhea, impotence (inability to have an erection during sex), reduced desire for sex, and infertility

53
Q

What are other causes of hyperprolactinemia (5)?

A
  1. Pituitary stalk interruption (damage)
  2. Dopamergic antagonist medications
  3. Thyroidal failure
  4. Renal failure
  5. Polycystic ovary syndrome
54
Q

Clinical evaluation of hyperprolactinemia requires what (3)?

A
55
Q

What are the therapeutic options for prolactinoma (4)?

A
  1. Simple observation
  2. Surgery
  3. Radiotherapy
  4. Medical management with dopamine (prolactin inhibitory hormone)
56
Q

What are the therapeutic goals for patients with prolactinoma (4)?

A
  1. Reduce tumor mass
  2. Restore normal gonadal function and fertility
  3. Prevent osteoporosis (Too much prolactin can reduce production of the hormones estrogen and testosterone, resulting in decreased bone density and an increased risk of osteoporosis)
  4. Preserve normal pituitary function
57
Q

What is idiopathic galactorrhea?

A

Lactation in women with normal prolactin levels, unknown cause

58
Q

Most pituitary gland tumors are ________ (benign/malignant), called pituitary adenomas, and develop in the _________ (anterior/posterior) of the gland

A

Benign, develop in anterior part of gland

59
Q

What is hypopituitarism?

A

Hypopituitarism is a rare disorder in which your pituitary gland fails to produce one or more hormones, or doesn’t produce enough hormones

60
Q

What is panhypopituitarism?

A

Complete loss of function. All hormones reduced or absent (can be due to head trauma)

61
Q

What is monotropic hormone deficiency?

A

Loss of production only a single hormone

62
Q

What should be measured when there is any suspicion of pituitary failure?

A

Measure tropic and target hormones

63
Q

What are causes of hypopituitarism (6)?

A
  1. Tumors
  2. Necrosis of pituitary gland
  3. Infiltrative diseases (which affect multiple parts of the body): sarcoidosis, an inflammatory disease occurring in various organs; Langerhans cell histiocytosis, in which abnormal cells cause scarring in numerous parts of the body; and hemochromatosis, which causes excess iron deposits in the liver and other tissues
  4. Infections of the brain, such as meningitis, or infections that can spread to the brain, such as tuberculosis or syphilis
  5. Lymphocytic hypophysitis - lymphocytes attacking pituitary gland, abnormal response, inflammation of pituitary
  6. Head trauma, surgery, radiotherapy (side effect to decrease tumor)
64
Q

What is the treatment for hypopituitarism?

A

Supplement with hormone therapy

65
Q

What is Sheehan’s syndrome?

A

Damage to the pituitary gland due to necrosis. Due to blood loss, oxygen depravation, and hypovolemic shock during and after childbirth.

Clinical Chemistry 2 (2 decks)

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