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Endo/Repro Exam 1 > 2. Histology of Endocrine Organs > Flashcards

2. Histology of Endocrine Organs Flashcards

1
Q

Both the endocrine and NS influence the physiology of organs. But, they differ in the ways they communicate and accomplish their task. How so?

A
  • NS communicates through depolarization and transmission of signal from synapses. Communication is fast but short-lived.
  • Endocrine system communicates through hormones that travel in the blood. They bind to specific receptors. Communication is slower, but longer-lived.
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2
Q

What are our three classes of hormones?

A
  1. Peptide/protein hormones
  2. Biogenic amines- small molecules made by changing the structure of an AA. Ex. Thyroid hormones or EPI.
  3. Steroid hormones.
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3
Q

What are three stimuli that control the release of hormones?

A
  1. Humoral stimuli: hormones are released d/t different levels of ions and nutrients in blood/body fluid.
  2. Neuronal stimuli: hormones are releasd d/t nerve signal
  3. Hormonal stimili: hormones are released d/t release of hormones into the blood.
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4
Q

Endocrine glands are ______________ and derived from ____________.

A
  • Endocrine glands are epitheloid cells (lack free surface) arranged as cords/follicles and some individual cells and derived from epithelia.
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5
Q

Are endocrine glands well-vascularized?

A

Yes. Vessels often have fenestrated endothelium.

Deliver material via blood.

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6
Q

_______ is the primary site where the CNS controls endocrine fx via the pituitary gland.

A

Hypothalamus.

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7
Q

Where is the hypothalamus located and what does it do?

A
  1. Located below thalamus, behind optic chaism and surrounds 3rd ventricle.
  2. Regulates metabolic processes and ANS.
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8
Q

Where is the pituitary gland (hypohysis) located?

A
  • Below hypothalamus.
  • It is a small gland that lives inside the hypopphyseal fossa of the sphenoid bone.
  • Divided into anterior (adenohypophysis) and posterior (neurohyposis) portion.
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9
Q

What connects the hypothalamus to the pituitary gland?

A

Thin stalk of tissue known as infundibulum

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10
Q

What are the direct targets of the hypothalamic hormones?

A
  1. Anterior pituitary via releasing hormones (RH) and inhibiting hormones (IH)
  2. Kidney and uterus via ADH and oxytocin.
  3. Adrenal medulla via sympathetic innervation.
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11
Q

What are the indirect targets of the hypothalamic hormones?

A
  • Hypothalamus can indirectly affect targets via tropic hormones, which stimulate or inhibit the release of hormones from the anterior pituitary onto:
    1. Thyroid gland
    2. Adrenal CTX
    3. Mammary glands
    4. Gonads
    5. Bones
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12
Q

80% of the pituitary gland is the anterior pituitary, made up of ________________ cells and controlled by neurohormones from the hypothalamus.

The posterior pituitary is made up of ________ from the hypothalamus and support cells.

A

glandular epithelial cells.

axons.

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13
Q

What are the parts of the anterior pituitary?

A
  1. Pars tuberalis- surrounds the infundibulum
  2. Pars intermedia
  3. Pars distalis
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14
Q

What are the parts of the posterior pituitary?

A
  1. Infundibular stalk
  2. Pars nervosa
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15
Q

What are the 5 major cell types of the anterior pituitary?

A
  1. Somatrotropic cells- secrete GH
  2. Thyrotropic cells- secrete TSH
  3. Corticotropic cells- secrete ACTH (act on adrenal gland to make cortisol) and MSH (act on melanocytes to make melanin)
  4. Gonadotropic cells- secrete FSH and LH
  5. Mammotropic cells- secrete prolactin
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16
Q

Describe the histology of the AP (pars distalis).

A
  1. Somatotrophs and mammotrophs are acidphils are and lightly stained.
  2. Corticotrophs, thyrtrophs and gonadotrophs are basophils and dark stained.
  3. Chromophobes- who knes what they. do.
  4. Sinusoidal capillaries.
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17
Q

Describe the histolgy. of the pars intermedia.

A
  • The pars intermedia is located in between the pars distalis and pars nervosa. In adults, it is rudimentary and we don’t know what the fuck it is.
  • Most cells are basophillic (basophils) and there are colloid filled follicles that. are surrounded by cuboidal epithelium.
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18
Q

The pars intermedia will often times have what located in it?

A

remnant of Rathke’s pouch can present as a large cleft or as small cysts

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19
Q

Describe the histolgy of the pars nervosa.

A
  • Pars nervosa is continous with the median eminence of the hypothalamus via the infundibular stalk. It does NOT make hormones. It stores and releases them.
  • Made up of:
    • hypothalamic unmyelinated axons called Herring bodies (axonal nerve terminals that store ADH and oxytocin)
    • pituicytes (glia-like) that support nerve fibers
    • fenestrated capillaries.
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20
Q

The infundibulum has 2 parts. What are they?

A
  1. Neural portion- part of the neurohypophysis connecting the pars nervosa and median eminence of the hypothalamus; made up of unmyelinated axons.
  2. Adenohypophysis portion- the pars tuberalis that surrounds the infundibubular stalk. it can form a total or partial collar; made of of many cuboidal cells arranged in cords.
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21
Q

How does the hypothalamus send hormones to the anterior pituitary?

A

Via the hypothalamo-hypophyseal portal system, which is made up of the primary capillary plexus, hypophyseal portal veins and secondary capillary plexus.

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22
Q

How does the anterior pituitary release horomones into the general circulation after being TRIGGRD by the hypothalamus?

A
  • Secondary capillary plexus, part of the hypothalamic hypophyseal portal system.
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23
Q

what causes the release of hormones from terminal axons in the posterior pituitary?

A

nerve impulses that traveled down the axons of hypothalamic neurons.

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24
Q

Are oxytocin and ADH made in the posterior pituitary?

A

No. They. are just. stored in vesicles in the posterior pituitary until hypothalamic signals fire and cause them to be released.

25
Q

What are the purpose of ADH and oxytocin?

A
  • ADH- targets the kidneys to regulate Na+ and water retention.
  • Oxytocin–> targets uterine smooth muscle and causes lactation, induces birth. Also involved in sexual arousal and bonding.
26
Q

Name the disorder: excess production of GH due to a tumor that occurs before the growth plates close, causing individuals to grow up to 8 feet tall.

A

Gigantism

27
Q

Name the disorder: excess production of GH due to a tumor that occurs after the growth plates close, causing enlargement of extrememities and organs.

A

Acromegaly

28
Q

What pituitary dwarfs?

A
  • Hyposecretion of GH.
  • Dwards will have normal body proportions but they rarely get. taller than 4 feet. If they are. given GH, they can reach normal stature.
29
Q

What is the pineal gland structure/location?

A

The pineal gland is cone-shaped and an out-pocketing of the diencephalons roof of 3rd ventricle. It is covered in pia mater.

30
Q

What. is the role of the pineal gland?

A
  • Growth, development and circadian rhythm
  • Makes melatonin and 5HT.
31
Q

Histologically, what does the pineal gland consist of?

A
  1. Pinealocytes
  2. Neuroglia
  3. Calcified granular material made up of Ca2+ phosphate crystals located in intracellular. spaces. They show up in early. childlood. and an important. marker for the midline of the brain
32
Q

What is the. anatomy. and blood supply of the. thyroid?

A
  • Anatomy: butterfly shaped, bi-lobed located below larynx and in front of the trachea.
  • BS: superior thyroid vessels and inferior thyroid vessels.
33
Q

Describe the histology of the the thyroid.

A
  • Thryoid follicles surrounded by follicular cells (simple cuboidal -> simple columnar) that surround a fluid called colloid.
  • Colloid contains thryoglobulin, a storage form of T3 and T4.
34
Q

What is so special about the thyroid?

A

it is the only gland to store hormones outside of the cell.

35
Q

Thyroid hormone is made and stored EXTRACELLULAR as ___________ ,which is made in the ______, glycosylated in the ______ and secreted by _________ into _________________.

A

Thyroid hormone is made and stored EXTRACELLULAR as thyroglobulin ,which is made in the rER , glycosylated in the golgi and secreted by exocytosis into the lumen of the follicle (colloid).

36
Q

Thyroid hormone is iodinated where?

A

at the apical surface, forming T3 and T4, which remains bound to thyroglobulin.

37
Q

How can we free up T3 and T4?

A
  • TSH stimulates internalization of thryoglobulin via endocytosis, where it is degraded, freeing up T3 and T4.
  • T3 and T4. then leave the via the basal surface–> circulation.
38
Q

What are parafollicular C cells?

A

PFC cells lie outside the follicles and secrete calcitonin when Ca2+ levels are high. They will

  • stimulate calcitonin secretion from kidneys
  • Decreases activity of osteoclassts
  • increase osteogenesis by osteoblasts.
39
Q

How does the thyroid gland secrete hormones?

A

Via the hypothalamic-anterior pituitary-thyroid axis.

  1. Stimulus causes hypothalamus to secrete TRH, which acts on the AP
  2. Thyrotropic cells in the AP release TSH.
  3. TSH acts on the thyroid gland, causing follicular cells to release thyroid hormone (TH)
  4. TH targets cells to increase metabolic activities (increase in basal body temp)
40
Q

Negative feedback in thryoid secretion.

A
  1. High TH levels–> heat production in target cells. Hypothalamus: DETECTS; inhibits TRH secretion.
  2. inhibit the binding of thyroid releasing hormone in the anterior pituitary.
41
Q

What is graves dz?

?:

Sx:

Tx:

A
  • A dz that is more common in women. Antibodies stimulate the TSH receptors and cause the oversecretion of T3 and T4.
  • Sx: high metabolism, sweating, rapid HR, weight loss, eyeballs protrude
  • Tx: thryoidectomy of anti-thyroid drugs
42
Q

What is hypothyroidism?

?:

Tx:

A
  • Decrease production of T3 and T4 often caused by an autoimmune disease that causes follicle cell death/
  • Tx: synthetic T3 and T4
43
Q

What are goiters?

A

Enlargement of thyroid d/t iodine deficiency. Follicles keep making thryoblobulin but cannot iodinate it to make TH.

44
Q

What are parathryoid glands?

A
  • Small glands that lie on the back of the thyroid gland that make parathyroid hormone (PTH).
    • ​PTH regulates Ca2+ and phosphate levels.
  • Has similar BS to the thyroid.
45
Q

What cells are located in the parathyroid gland? (2)

A
    1. Chief (principle) cells that secrete PTH when levels of Ca2+ fall below normal.
      * Stain more basophilic
    1. Oxyphil cells- unknown fx. Related to aging and appear l8r in lyfe
      * Larger and stain more acidophillic.
46
Q

Describe the actions of PTH.

A

When our blood Ca2+ levels drop below 9.5 mg/dL, PTH is is released into blood.

  1. Stimulates osteoclast activity
  2. Increase Ca2+ retention by the kidkneez
  3. Causes kidkneez to convert inactive vitamin D–> calcitrol (active), which increases Ca2+ aborption by intestines.

When our Ca2+ levels increase, inhibits PTH release.

47
Q

The adrenal gland has a adrenal medulla** and a **adrenal CTX.

What are the zones of the adrenal gland.

A

From outside to inside:

Adrenal CTX:

  • zona glomerulosa
  • zona fasciculata
  • zona reticularis

Adrenal medulla

  • adrenal medulla
48
Q

The adrenal cortex is a distinct yellow color. Why?

A

Bc it stores lipids.

49
Q

Why is the adrenal CTX NEEDED to survive.

A

it secretes more than 25 different corticosteroid hormones

50
Q

Adrenal CTX is divided into 3 structurally and functionally different zones.

What are they?

A

“Salt, sugar, sex. The deeper you go the sweeter it gets.”

  1. Zona glomerulosa (mineralcorticoids) influences Na+, K+ and salt secretion.
    1. Releases aldosterone in response to low BP or BV
  2. Zona fasiculata (glucocorticoids) influences glucose metabolism and the immune metabolism
    1. Secretes cortisol under the control of ACTH from the AP.
  3. Zona reticularis (androgens) affects secondary sex characteristics.
51
Q

What is located within the adrenal medulla?

A

Our adrenal medulla is made up of large spherical cells called chromaffin cells. When sympathetically stimulated, they release NE and EPI.

52
Q

Chromaffin cells in the adrenal medulla secrete NE and EPI. How can we distinguish between the cells that release NE and EPI?

A
  • EPI cells are smaller and less electron dense.
  • NE cells are larger and more electron dense.
53
Q

What is Addison’s Disease?

Results in:

D/t:

A

Hyposecretion glucocorticoids and mineralcorticoids from the adrenal CTX.

Results in: low blood glucose levels and low blood Na+ levels.

D/t: autoimmune dz or inherited metabolic dz

54
Q

What is Cushing’s syndrome?

A

Hypersecretion of glucocorticoids d/t ACTH secreting tumor in AP or adrenal CTX tumor.

Results in: High blood glucose levels, protein loss in muscles, muscle weakness and fatigue.

55
Q

Sx of Cushings syndrome

A

swollen face, fat redistribution (buffalo hump and moon face), high glucose levels, weight gain, thinning skin

56
Q

The pancreas is made of a endocrine and exocrine portion. The exocrine portion makes up most of the gland and helps with digestion. Cells are located in pancreatic acini.

What about endocrine cells?

A

Endocrine cells in the pancreas are organized into:

  • 1. Pancreatic islets
  • 2. Islets of langerhans

which are scattered amongst the exocrine cells.

57
Q

Describe the

Alpha cells

Beta cells

Delta cells

F-cells

of the endocrine pancreas.

A
  • Alpha cells- secrete glucagon when glucose levels drop; causes release of glucose from liver glycogen stores.
  • Beta cells- secrete insulin when glucose levels are high.
  • Delta cells- secrete somatostatin and slows the release of insulin and glucagon to control rate of nutrient entry into the blood and cells. Released by high levels of nutrients in blood.
  • F cells- secrete pancreatic polypeptide that inhibit release of somatostatin.
58
Q

The pancreas has TWO blood supplies. What are they?

A
  1. The islets of Langerhans have a blood supply directly, called the insuloacinar portal system. This insuloacinar portal system, after leaving the islets of Langerhans, supplies the pancreatic acinar cells surrounding the islets and can carry endocrine hormones to the acinar cells and affect them there.
  2. The pancreatic acinar have their own vascular system as well, called the acinar vascular system.
59
Q

List some organs having endocrine functions but are not usually thought of as being endocrine organs.

A
  1. Gonads- estrogen, testosterone, progesterone
  2. Heart- ANP
  3. GI- peptides that regulate digestion
  4. Placenta- estrogen, progesterone, HCG
  5. Kidney- renin, erythropoietin
  6. Skin- precursor to vit D

Endo/Repro Exam 1 (14 decks)

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