pack Flashcards

1
Q

Where is the piuitary gland located?

A

At the base of the sphenoid bone in the sella turicia (turkish saddle)

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2
Q

What attaches the hypophysis to the hypothalamus?

A

The infundibulum

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3
Q

What are the two functional componets of the hypophysis?

A

The hypophysis has two functional components
Adenohypophysis (anterior pituitary)
Neurohypophysis (posterior pituitary)

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4
Q

Label

A
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5
Q

What are the two nuclei that pass from the hypothalamus to the posterior pituitary gland?

A

Paraventricular hypothalmic nucleus

Supraoptic hypothalmic nucleus

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6
Q

Label

A
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7
Q

LAbel

A
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8
Q

What is the area above the hypophysis covered by?

A

It is covered by a diaphragm

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9
Q

Label the covered

A
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10
Q

What is a common symptom of a tumor in the pituitary gland?

A

Loss of bitemporal vision (Bitemporal hemianopsia) bc of the fact that the tumor will compress the optic chaism

The tumor can also compress the cranial nerves

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11
Q

Label

A
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12
Q

What artery forms the primary capillary plexus and where is it located?

A

Artery: Superior hypophyseal artery

Located: In the hypothalamus

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13
Q

What veins form the secondary capillary plexus and where is it located?

A

Long portal veins

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14
Q

What does the inferior hypophseal artery supply?

A

The posterior pituitary

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15
Q

What is the reason for the two plexuses?

A

The reason for these plexuses is that the hormones from the hypothalamus enter the primary plexus then travel through the secondary plexus to the anterior pituitary to stimulate the release of its hormones.

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16
Q

What are the hormones of the hypothalamus?

A

Gonadotropin-releasing hormone
Thyrotropin-releasing hormone
Corticotropin-releasing hormone
Prolactin-releasing hormone
Prolactin-inhibiting hormone
Growth hormone-releasing hormone
Somatostatin

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17
Q

What are the hormones released by the secondary plexus (anterior pit)?

A

Follicle-stimulating hormone
Luteinizing hormone
Thyroid-stimulating hormone (thyrotropin)
Adrenocorticotropic hormone
Prolactin
Growth hormone

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18
Q

What two embryological structures form the pituitary gland?

A

The rathke’s pouch (anterior pituitary) and the diverticulum (infundiblum) forms the posterior pituitary gland

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19
Q

What are the 4 trophic and 2 non trophic hormones of the anterior pituitary gland?

A

4 Trophic Hormones (from the anterior pituitary):
Adrenocorticotropic Hormone (ACTH):

Thyroid-Stimulating Hormone (TSH):

Follicle-Stimulating Hormone (FSH):

Luteinizing Hormone (LH):

======

Non-Trophic Hormones (from the anterior pituitary):
Growth Hormone (GH, or Somatotropin):

Prolactin (PRL):

Acts directly on the mammary glands to stimulate milk production.

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20
Q

What are the three cell types found in the tissues of the adenohypophysis that are characterized based on appearance?

A

Basophils (blue and large)

Acidophils (pink and large)

Chromophobes (Purple and small very round)

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21
Q

Label

22
Q

What are somatotropes and what is their function?

A

They are: Acidophils

Function: Release GH and effect the liver and cause it to release IGF1

23
Q

What are lactotropes and what is their function?

A

They are: Acidophils

Function: Release prolactin

24
Q

What do lactotropes appear as when there is no prolactin?

A

They appear as chromophobes

25
Q

What does an increase in PRL cause in both men and women?

A

High levels of prolactin can cause FSH and LH to decrease which can decrease spermatogensis in males and inhibt the menstrual cycle in women

26
Q

What are cortictropes and what is their function?

A

They are: Basophils

Function: Release POMC which is then cleaved into ACTH and B-LPH

27
Q

What are gonadotropes and what is their function?

A

They are: Basophils

Function: Release FSH and LH

28
Q

What are thyrotropes and what is their function?

A

They are: Basophils

Function: TSH

30
Q

What are the causes of growth hormone deficiency?

A
  1. Hypothalamic dysfunction: Decreased secretion of GHRH.
  2. Anterior pituitary dysfunction: Primary deficiencies in growth hormone secretion.
  3. Liver dysfunction: Failure to generate somatomedins (IGFs).
  4. Target tissue dysfunction: Deficiency of growth hormone or somatomedin receptors (growth hormone resistance).
31
Q

What is Laron dwarfism, and why is treatment with growth hormone ineffective?

A
  1. A variant of dwarfism characterized by elevated growth hormone levels but ineffective treatment with growth hormone.
  2. Caused by defective growth hormone receptors, preventing growth hormone from stimulating IGF production in target tissues.
32
Q

What condition is caused by growth hormone excess, and what is its most common cause?

A

Acromegaly is caused by growth hormone excess.

Most often due to a growth hormone–secreting pituitary adenoma.

33
Q

What is gigantism, and when does it occur?

A

Gigantism is caused by excess growth hormone before puberty.

Results in increased linear growth due to stimulation at the epiphyseal plates.

34
Q

What are the consequences of growth hormone excess after puberty?

A

Increased periosteal bone growth, increased organ size, increased hand and foot size, enlargement of the tongue, coarsening of facial features, insulin resistance and glucose intolerance.

35
Q

How is growth hormone excess treated?

A

Treated with somatostatin analogues (e.g., octreotide).

These drugs inhibit growth hormone secretion by the anterior pituitary, similar to endogenous somatostatin.

36
Q

What are the causes of undersecretion of pituitary hormones?

A
  1. Nonsecreting pituitary adenoma or craniopharyngioma.
  2. Sheehan syndrome: Ischemic infarct of the pituitary following postpartum bleeding.
  3. Empty sella syndrome: Atrophy or compression of the pituitary, often idiopathic.
  4. Pituitary apoplexy: Sudden hemorrhage of the pituitary gland, often with an existing adenoma.
  5. Brain injury or radiation.
37
Q

What is Sheehan syndrome, and how does it present?

A
  1. Ischemic infarct of the pituitary following postpartum bleeding.
  2. Pregnancy-induced pituitary growth increases susceptibility to hypoperfusion.
  3. Presents with:
    • Failure to lactate.
    • Absent menstruation.
    • Cold intolerance.
38
Q

What is empty sella syndrome, and who is most commonly affected?

A
  1. Atrophy or compression of the pituitary gland (located in the sella turcica).
  2. Often idiopathic and common in obese females.
  3. Associated with idiopathic intracranial hypertension.
39
Q

What is pituitary apoplexy, and how does it present?

A
  1. Sudden hemorrhage of the pituitary gland, often in the presence of an existing pituitary adenoma.
  2. Presents with:
    • Sudden onset severe headache.
    • Visual impairment (e.g., bitemporal hemianopia, diplopia due to CN III palsy).
    • Features of hypopituitarism.
40
Q

How is pituitary hormone undersecretion treated?

A
  1. Hormone replacement therapy, including:
    • Corticosteroids.
    • Thyroxine.
    • Sex steroids.
    • Human growth hormone.
41
Q

Where is prolactin mainly secreted from?

A

Prolactin is mainly secreted by the anterior pituitary.

42
Q

What are the functions of prolactin?

A
  1. Stimulates milk production in the breast.
  2. Inhibits ovulation in females and spermatogenesis in males by inhibiting GnRH synthesis and release.
43
Q

How is prolactin secretion regulated?

A
  1. Tonic inhibition by dopamine from the tuberoinfundibular pathway of the hypothalamus.
  2. Prolactin inhibits its own secretion by increasing dopamine synthesis and secretion from the hypothalamus.
  3. TRH increases prolactin secretion (e.g., in primary or secondary hypothyroidism).
44
Q

How is prolactin structurally related to growth hormone?

A

Prolactin is structurally homologous to growth hormone.

45
Q

What is diabetes insipidus, and what are its key symptoms?

A

A condition caused by absence or reduced ADH production or lack of renal response to ADH.

Symptoms: Polyuria (up to 20 L/day of diluted urine), hypotonic urine, and extreme thirst.

46
Q

What causes hypothalamic diabetes insipidus, and how is it treated?

A

Caused by head injuries, tumors, or lesions affecting the hypothalamus or posterior pituitary.

Treated with synthetic ADH analogs (desmopressin).

47
Q

What causes nephrogenic diabetes insipidus, and how is it treated?

A

Caused by mutations in AQP-2 water channels or ADH V2 receptors in kidney tubules.

Treated by reducing urine output.

48
Q

What is SIADH, and what are its key features?

A

A condition caused by abnormally high ADH levels, leading to:

Hyponatremia (low sodium).
Decreased serum osmolality.
Concentrated urine.

49
Q

What are the common causes of SIADH?

A

CNS disorders (tumors, injuries, infections).
Pulmonary diseases (pneumonia, COPD).
ADH-secreting tumors (e.g., small-cell lung carcinoma).
Certain drugs (anti-inflammatories, nicotine, diuretics).

50
Q

How is SIADH treated?

A

Fluid restriction.
ADH V2-receptor antagonists (e.g., Conivaptan) to improve hyponatremia and promote free water diuresis.