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

1-endocrine System Flashcards

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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
What are pituitary adenomas?
Benign tumors 10-15% of all brain tumors
26
What are the general symptoms of pituitary adenomas?
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
27
What are the symptoms of the prolactinoma
Nipple secretion, amenorrhea, sexual dysfunction
28
What are the symptoms of somatotropic adenoma-Growth hormone?
Acromegaly in adult, gigantism in adolescence
29
What are the symptoms of the Corticotropin adenoma?
Cushings disease
30
What are the symptoms of thyrotropic adenoma?
Hyperthyroidism
31
What are the adrenal glands?
The adrenals are paired glands located at the superior pole of the kidneys ― Capsule ― Parenchyma arranged : cortex and medulla
32
What are the embryological origins of the adrenal glands?
Embryonic Development : ― Cortex develops from mesoderm ― Medulla from neural crest cellssympathetic ganglion
33
Describe the capsule of the adrenal gland
Dense connective tissue supplied with many small arteries, which pierce it and empty into the enlarged fenestrated capillaries (cortical sinusoids) of the adrenal cortex.
34
Describe the cortex of the adrenal gland
Paler-staining region—>steroid- producing cells
35
Describe the medulla of the adrenal gland
Central | • Large blood vessels
36
How much of the weight of the adrenal gland is made up of Steroid secreting cells ?
90% of gland by weight
37
What is the functional significance of the zona glomerulosa?
``` Zona glomerulosa (~15%): ― aldosterone (mineralocorticoid) ― electrolyte and water balance ― Feedback control from Renin-angiotensin II- aldosterone system ```
38
Whaat is the function of the zona fasciculata?
Zona fasciculata (~80%) ― Mainly glucocorticoid(cortisol) ― some androgens
39
What is the impact of zona reticularis?
Zona reticularis (~5-7% ― mainly androgens ― some glucocorticoids
40
What zones of the adrenal glands have receptors for ACTH from pituitary?
Zona fasciculata and zona reticularis
41
What is released from the zona glomerulosa?
Mineralcorticoid | -aldosterone
42
What is released by the zona fasciculata?
Glucocorticoids - Cortisol - corticosterone Gonadocorticoids - DHEA - DHEAS - androstenedione
43
What is released by zona reticularis?
Gonadocorticoids - DHEA - DHEAS - androstenedione Glucocorticoids - Cortisol - corticosterone
44
What is released by the medulla of the adrenal glands?
Catecholamines - epinephrine - norepinephrine
45
Describe the structure of the glomerulosa
- 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
Describe the structure of the fasciculata
-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
What is the fasciculata stimulated by?
ACTH
48
What does the fasciculata once stimulated by ACTH?
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
Describe the structure of the zona reticularis
- Irregular cords of small cells - The cytoplasm MSY contain brown lip chrome pigment - Regulated by ACTH - Weak androgens and some Cortisol
50
What is the main clinical correlate to the zona reticularis ?
Addison’s disease( hypoadrenalism) - destruction of both adrenals (usually autoimmune) - Deficiency of all hormones - Weakness, weight loss, muscle pain, hypotension, electrolyte imbalances, hyperpigmentation
51
Describe the structure of the medulla of the adrenal gland
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
Explain what are chromaffin cells
``` 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
What are chromatin cells responsible for?
Secretions (catecholamines) - 85% Epinephrine | - Norepinephrine
54
How are chromaffin cells stimulated?
By preganglionic sympathetic neurons in fight or flight response
55
What is a “Ganglion” cell?
Axonal processes extend into cortex and modulate the secretion Innervate blood vessels of cortex
56
Explain in detail the blood supply of the adrenal glands
• 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
What are pheochromocytomas?
Excessive amounts of catecholamines due to tumor to chromaffin cells ― Most secrete norepinephrine ― Pg. 772: Effects associated with adrenergic receptor stimulation ― Hypertension, arrythmias
58
What do pheochromocytomas look like?
reddish brown with a prominent area of fibrosis | ― polyhedral tumor cells with a finely granular cytoplasm and enlarged hyperchromatic nuclei.
59
How can we use immunological staining to identify pheochromocytomas?
Tumor cells show positive immunohistochemical staining for chromogranin A
60
Where is the pineal gland/epiphysis cerebri located?
Posterior wall of 3rd ventricle
61
What forms the pineal gland/ epiphysis cerebri?
Pia mater forms capsule and septae Parenchyma • Pinealocytes are arranged in cords • Glial cells – astrocytes
62
Where does nervous input for the pineal gland/epiphysis cerebri originate?
Nerve input from from postganglionic sympathet8c fibers der8ved from superior cervical ganglion
63
What is the thyroid gland?
Butterfly-shaped: 2 lobes and central isthmus
64
What is the capsule of the thyroid made of?
Capsule: entire gland covered by capsule of | connective tissue
65
Summarize the hormonal activity of the thyroid
Stimulating hormone- TSH • Secretion – T3 and T4 • regulates metabolic activity
66
Describe the parenchyma of the thyroid gland
Colloid-filled follicle lined by follicular cells
67
Describe the stroma of the thyroid
― Connective tissue ― Fenestrated capillaries ― Parafollicular or “C” cells
68
Thyroid follicles are lined by…
Thyroid epithelium ― follicular cells- typically simple cuboidal ― Polarity of cells – apex faces the colloid
69
What inactive hormone resides in the thyroid colloid?
Thyroglobulin
70
What are the thyroid parafolliculsr cells ?
C cells /clear cells ― Cluster of cells within follicular basal lamina ― Secrete calcitoninlowers blood calcium levels by directly suppressing osteoclast activity
71
What is hyperthyroidism ?
Excessive amounts of thyroid hormones | • Toxic goiter or Grave’s disease: autoimmune—>anti-TSH receptor antibodies—>stimulate follicular cells
72
Whaat are the clinical features of hyperthyroidism?
• Clinical: ―Low TSH ―Increased metabolic rate and sympathetic activity ―Weight loss, sweating, heat intolerance tachycardia, exophthalmos
73
Whaat is the histopathology of hyperthyroidism?
―Decreased colloid | ―Columnar follicular epithelium
74
What are the types of cells in the parathyroid gland? What is the function of each?
``` Cell types 1. Principal or Chief cells • Small densely packed • Parathyroid hormone (PTH) • Increases blood calcium levels • Decreases blood phosphate levels ``` 2. Oxyphil cells • Large, acidophilic cells
75
What is the anatomical location of the pancreas?
Abdomen Retroperitoneal
76
Where are the endocrine units of the pancreas?
Islets of langerhans About 1 million islets More towards the tail
77
What is the function of alpha cells of the pancreas?
Alphacells • ~20% of gland • Secrete glucagon increase blood glucose • Peripheral location
78
What is the function of the beta cells of the pancreas?
``` • ~70% of gland • Central core of the islets • Secrete insulindecreases blood glucose • Clinical correlate diabetes mellitus ```
79
Whaat is the impact of the delta cells in the pancreas?
Delta cells • ~5% of gland • scattered between a and b cells • Somatostatin
80
What is the impact of the F-cells in the pancreas?
* ~5% of gland | * Pancreatic polypeptide
81
What is diabetes insipidus ?
• Inability concentrate their urine Chronic water diuresis (polyuria) hypotonic urine Thirst and polydipsia(excessive drinking) Hypernatremia
82
What are the types of diabetes insipidus?
* Hypothalamic: * lack enough ADH (vasopressin). * Causes: tumor, head injury Nephrogenic • Congenital mutation of aquaporins
83
What is diabetes mellitus?
``` Defective Glucose metabolism • Elevated blood glucose • Glucosuria • Frequent urination • Increased hunger and thirst ```
84
What are the types of diabetes mellitus?
* 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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