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Endocrine And Reproductive System Class > 1-endocrine System > Flashcards

1-endocrine System Flashcards

1
Q

What is the relationship between pituitary and hypothalamus?

A

The pituitary gland or hypophysis is found in sella turcica of sphenoid bone

Attached to the hypothalamus

Functionally, the hypothalamus regulates secretion from the hypophysis

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2
Q

Describe The embryological divisions of the pituitary gland (Hypophysiss)

A
  1. Anterior lobe or Adenohypophysis

2. Posterior lobe or Neurohypophysis

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3
Q

What is the embryological origin of the posterior lobe/neurohypophysis of the pituitary?

A

-Neuroectoderm of the floor of the diencephalon
A. Pars nervosa
B. Infundibulum

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4
Q

Whaat is the embryological origin of the anterior lobe of adrenohypophysis of the pituitary?

A

-Ectoderm of the oropharynx (Rathke’s pouch)
A. Pars distalis
B. Pars intermedia
C. Pars tuberalis

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5
Q

What is the general appearance of the adenohypophysis?

A

Granular appearance due to clusters of endocrine tissue

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6
Q

What is the general appearance of the neurohypophysis?

A

Fibrous appearance—> mostly nerve fibers

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7
Q

What is the composition of chromophils and chromophobes in the anterior lobe?

A

50% for each

Chromophils
Acidophils
Basophils

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8
Q

What are the acidophils?

A
  • Somatotrophs

- Mammotropes/Lactotropes

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9
Q

What are the basophils?

A

Gonadotropes

Corticotropes

Thyrotropes

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10
Q

What do basophils do?

A

Secreted hormones that act on other endocrine organs—> tropic hormones

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11
Q

What do somatotropes do?

A

Stimulated by GHRH —> growth hormone (also called somatotropin)

Inhibited by somatostatin

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12
Q

What do Mammotropes/lactotropes do?

A
  • Secretes prolactin (PRL)
  • stimulated by prolactin-releasing hormone (PRH) (under certain conditions such as pregnancy)
  • Inhibited by dopamine produced by hypothalamus (dopamine is the main regulator of prolactin)
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13
Q

What do gonadotropes do?

A

FSH- follicle-stimulating hormone
LH- lutenizing hormone
Stimulated by gonadotropin releasing hormone

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14
Q

What does corticotropes do?

A

-Secrete ACTH-adrenocorticotropin

Stimulated by Corticotropin releasing hormone

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15
Q

What do thyrotropes do?

A

-TSH- thyroid stimulating hormone

Stimulated by thyrotropin releasing hormone

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16
Q

How do we identify chromophobes?

A

Cytoplasmic granules do not stain with routine stains

Cytoplasm appears pale

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17
Q

What is the function of chromophobes?

A

Stem cells
Supportive cells
Degranulated cells

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18
Q

Pars intermedia and tuberalis are remnants of …

A

Rathke’s pouch

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19
Q

What are the follicular structures of pars intermedia and tuberalis?

A

Cystic cavities, lined by basophilic cuboidal cells —> assumed to be corticotropes

Associated with Beta-lipotrophic hormones

Animal studies:
MSH (a-melanocyte stimulating hormone)
Endorphins —> morphine related

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20
Q

What does the pars tuberalis do?

A

Pars tuberalis forms a sheath around the infundibulum

Nests of squamous cells and small follicles

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21
Q

What 8s the function of pars nervosa for the posterior pituitary?

A

Stores hormones produced by hypothalamic nuclei
-Supraoptic nuclei—> Antidiuretic hormone (ADH)/vasopressin

  • Paraventricular nucleus —> oxytocin
    • Uterine smooth muscle
    • Myoepithelial cells of mammary gland

Carried along axons which form hypothalamo-hypophyseal tract

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22
Q

Describe the histology of the posterior pituitary/neurophysis

A

-unmyelinated axons

  • Herring bodies:
    • dilation of axons which contain hormones
    -Hormones bound by neurophysin

Most nuclei are of the pituicytes (glial-like cell)

  • +Glial fibrillary acidic protein —> intermediate filaments
  • Branched shape with oval nuclei
  • supportive
  • Nutritive

Some fibroblasts and mast cells

Fenestrated capillaries

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23
Q

Describe the blood supply and regulation hypophyseal function for the adenohypophysis

A

adenohypophysis:
―Releasing and inhibiting factors from hypothalamic nuclei released into primary capillary network
―Hypothalamo-hypophyseal portal veins carries factors to a secondary network at pars distalis
―Regulate secretion of pars distalis ―Pars distalis secrete into secondary
network—>systemic circulation

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24
Q

Describe the blood supply regulation of hypophyseal function for the neuro hypotphysis

A

For the neurohypophysis

Hormone transported by H-H tract from Nuclei and released into capillary plexus at pars nervosa

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25
Q

What are pituitary adenomas?

A

Benign tumors

10-15% of all brain tumors

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26
Q

What are the general symptoms of pituitary adenomas?

A

General symptoms due to tumor ― Headaches
― Vision problems (double vision, vision loss)
― Nausea or vomiting
― Changes in behavior, including hostility, depression and anxiety
― Nasal drainage

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27
Q

What are the symptoms of the prolactinoma

A

Nipple secretion, amenorrhea, sexual dysfunction

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28
Q

What are the symptoms of somatotropic adenoma-Growth hormone?

A

Acromegaly in adult, gigantism in adolescence

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29
Q

What are the symptoms of the Corticotropin adenoma?

A

Cushings disease

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30
Q

What are the symptoms of thyrotropic adenoma?

A

Hyperthyroidism

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31
Q

What are the adrenal glands?

A

The adrenals are paired glands located at the superior pole of the kidneys
― Capsule
― Parenchyma arranged : cortex and medulla

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32
Q

What are the embryological origins of the adrenal glands?

A

Embryonic Development :
― Cortex develops from mesoderm
― Medulla from neural crest cellssympathetic ganglion

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33
Q

Describe the capsule of the adrenal gland

A

Dense connective tissue supplied with many small arteries, which pierce it and empty into the enlarged fenestrated capillaries (cortical sinusoids) of the adrenal cortex.

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34
Q

Describe the cortex of the adrenal gland

A

Paler-staining region—>steroid- producing cells

35
Q

Describe the medulla of the adrenal gland

A

Central

• Large blood vessels

36
Q

How much of the weight of the adrenal gland is made up of Steroid secreting cells ?

A

90% of gland by weight

37
Q

What is the functional significance of the zona glomerulosa?

A 
Zona glomerulosa (~15%):
― aldosterone (mineralocorticoid)
― electrolyte and water balance
― Feedback control from Renin-angiotensin II-
aldosterone system
38
Q

Whaat is the function of the zona fasciculata?

A

Zona fasciculata (~80%)
― Mainly glucocorticoid(cortisol)
― some androgens

39
Q

What is the impact of zona reticularis?

A

Zona reticularis (~5-7%
― mainly androgens
― some glucocorticoids

40
Q

What zones of the adrenal glands have receptors for ACTH from pituitary?

A

Zona fasciculata and zona reticularis

41
Q

What is released from the zona glomerulosa?

A

Mineralcorticoid

-aldosterone

42
Q

What is released by the zona fasciculata?

A

Glucocorticoids

  • Cortisol
  • corticosterone

Gonadocorticoids

  • DHEA
  • DHEAS
  • androstenedione
43
Q

What is released by zona reticularis?

A

Gonadocorticoids

  • DHEA
  • DHEAS
  • androstenedione

Glucocorticoids

  • Cortisol
  • corticosterone
44
Q

What is released by the medulla of the adrenal glands?

A

Catecholamines

  • epinephrine
  • norepinephrine
45
Q

Describe the structure of the glomerulosa

A
  • Loops or arcades of small cells
  • 1-2 layers thick
  • Aldosterone production

Clinical correlate: Conn’s syndrome (primary aldosteronism) —> hypertension, potassium deficiency (cramps, muscle weakness and spasms)

46
Q

Describe the structure of the fasciculata

A

-Linear cords of polyhedral cells 1-2 layers

Fenestrated capillaries between columns

Cells are called spongiocytes

― Several lipid droplets —>foamy appearance
― Pale spherical nuclei
― Well-developed smooth ER
― Mitochondria with tubular cristae

47
Q

What is the fasciculata stimulated by?

48
Q

What does the fasciculata once stimulated by ACTH?

A

Secrete glucocorticoids (corticosterone, Cortisol)

  • carbohydrate and fat metabolism
  • inflammatory suppression

Clinical correlate: tumors or hyperplasia can cause increased glucocorticoid secretion—> Cushing’s syndrome

-Not to be confused with Cushings disease: pituitary origin—> increased ACTH —> increased glucocorticoids

49
Q

Describe the structure of the zona reticularis

A
  • Irregular cords of small cells
  • The cytoplasm MSY contain brown lip chrome pigment
  • Regulated by ACTH
  • Weak androgens and some Cortisol
50
Q

What is the main clinical correlate to the zona reticularis ?

A

Addison’s disease( hypoadrenalism)

  • destruction of both adrenals (usually autoimmune)
  • Deficiency of all hormones
  • Weakness, weight loss, muscle pain, hypotension, electrolyte imbalances, hyperpigmentation
51
Q

Describe the structure of the medulla of the adrenal gland

A

Large muscular-walled central vein.
• Cells arranged in cords surrounded by fenestrated capillaries (medullary sinusoids)
• Two cell types
• Chromaffin cells
• Ganglion cells
*Cells making norepinephrine stain darker than those making epinephrine

52
Q

Explain what are chromaffin cells

A 
Chromaffin cells or pheochromocytes
Modified post- ganglionic sympathetic
neurons
― no axons / dendrites!
― Brown granulation due to the chromaffin
reaction—>oxidation of the catecholamines with
dichromate salts
― chromogranin—>proteins that bind the
catecholamines within cytoplasm.
53
Q

What are chromatin cells responsible for?

A

Secretions (catecholamines) - 85% Epinephrine

- Norepinephrine

54
Q

How are chromaffin cells stimulated?

A

By preganglionic sympathetic neurons in fight or flight response

55
Q

What is a “Ganglion” cell?

A

Axonal processes extend into cortex and modulate the secretion

Innervate blood vessels of cortex

56
Q

Explain in detail the blood supply of the adrenal glands

A

• Suprarenal arteries
1. Capillaries of the capsule
2. Subcapsular plexus which branches into
A. Cortical capillaries
• Supplies cortexfenestrated cortical
sinusoidal capillaries
• Drains into medullary capillaries
B. Medullary arteriole ( long cortical arteries)medullary capillaries
• Central vein (suprarenal vein): received blood from medullary capillaries
• Medulla receives dual blood supply

57
Q

What are pheochromocytomas?

A

Excessive amounts of catecholamines due to
tumor to chromaffin cells
― Most secrete norepinephrine
― Pg. 772: Effects associated with
adrenergic receptor stimulation ― Hypertension, arrythmias

58
Q

What do pheochromocytomas look like?

A

reddish brown with a prominent area of fibrosis

― polyhedral tumor cells with a finely granular cytoplasm and enlarged hyperchromatic nuclei.

59
Q

How can we use immunological staining to identify pheochromocytomas?

A

Tumor cells show positive immunohistochemical staining for chromogranin A

60
Q

Where is the pineal gland/epiphysis cerebri located?

A

Posterior wall of 3rd ventricle

61
Q

What forms the pineal gland/ epiphysis cerebri?

A

Pia mater forms capsule and septae

Parenchyma
• Pinealocytes are arranged in cords
• Glial cells – astrocytes

62
Q

Where does nervous input for the pineal gland/epiphysis cerebri originate?

A

Nerve input from from postganglionic sympathet8c fibers der8ved from superior cervical ganglion

63
Q

What is the thyroid gland?

A

Butterfly-shaped: 2 lobes and central isthmus

64
Q

What is the capsule of the thyroid made of?

A

Capsule: entire gland covered by capsule of

connective tissue

65
Q

Summarize the hormonal activity of the thyroid

A

Stimulating hormone- TSH
• Secretion – T3 and T4
• regulates metabolic activity

66
Q

Describe the parenchyma of the thyroid gland

A

Colloid-filled follicle lined by follicular cells

67
Q

Describe the stroma of the thyroid

A

― Connective tissue
― Fenestrated capillaries
― Parafollicular or “C” cells

68
Q

Thyroid follicles are lined by…

A

Thyroid epithelium

― follicular cells- typically simple
cuboidal
― Polarity of cells – apex faces the
colloid

69
Q

What inactive hormone resides in the thyroid colloid?

A

Thyroglobulin

70
Q

What are the thyroid parafolliculsr cells ?

A

C cells /clear cells

― Cluster of cells within follicular basal
lamina
― Secrete calcitoninlowers blood
calcium levels by directly suppressing osteoclast activity

71
Q

What is hyperthyroidism ?

A

Excessive amounts of thyroid hormones

• Toxic goiter or Grave’s disease: autoimmune—>anti-TSH receptor antibodies—>stimulate follicular cells

72
Q

Whaat are the clinical features of hyperthyroidism?

A

• Clinical: ―Low TSH
―Increased metabolic rate and sympathetic activity
―Weight loss, sweating, heat intolerance tachycardia, exophthalmos

73
Q

Whaat is the histopathology of hyperthyroidism?

A

―Decreased colloid

―Columnar follicular epithelium

74
Q

What are the types of cells in the parathyroid gland? What is the function of each?

A 
Cell types
1. Principal or Chief cells
• Small densely packed
• Parathyroid hormone (PTH)
• Increases blood calcium levels
• Decreases blood phosphate levels
  1. Oxyphil cells
    • Large, acidophilic cells
75
Q

What is the anatomical location of the pancreas?

A

Abdomen

Retroperitoneal

76
Q

Where are the endocrine units of the pancreas?

A

Islets of langerhans

About 1 million islets

More towards the tail

77
Q

What is the function of alpha cells of the pancreas?

A

Alphacells
• ~20% of gland
• Secrete glucagon increase blood glucose
• Peripheral location

78
Q

What is the function of the beta cells of the pancreas?

A 
• ~70% of gland
• Central core of the islets
• Secrete insulindecreases blood
glucose
• Clinical correlate diabetes mellitus
79
Q

Whaat is the impact of the delta cells in the pancreas?

A

Delta cells
• ~5% of gland
• scattered between a and b cells
• Somatostatin

80
Q

What is the impact of the F-cells in the pancreas?

A
  • ~5% of gland

* Pancreatic polypeptide

81
Q

What is diabetes insipidus ?

A

• Inability concentrate their urine
Chronic water diuresis (polyuria) hypotonic urine
Thirst and polydipsia(excessive drinking) Hypernatremia

82
Q

What are the types of diabetes insipidus?

A
  • Hypothalamic:
  • lack enough ADH (vasopressin).
  • Causes: tumor, head injury

Nephrogenic
• Congenital mutation of aquaporins

83
Q

What is diabetes mellitus?

A 
Defective Glucose metabolism
• Elevated blood glucose
• Glucosuria
• Frequent urination
• Increased hunger and thirst
84
Q

What are the types of diabetes mellitus?

A
  • Type 1
  • Childhood/adolescence
  • Loss of islet cellsDeficiency in insulin secretion
  • ?Autoimmune
  • Type II
  • Adult
  • Insulin resistance of target cells

Endocrine And Reproductive System Class (36 decks)

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