Endocrine II Flashcards by Jassie McGovern

Describe the covering of the parathyroid glands.

Covered by a collagenous connective tissue capsule which send septa that carry blood vessels, lymphatic vessels, and nerve fibers into the glands

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What forms the supporting framework of the parathyroid glands.

Septa and reticular fibers form a supporting framework

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What type of capillary network is found in the parathyroid glands?

a fenestrated capillary network

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What percentage of the parathyroid gland is adipose tissue in the adult?

60-70%

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How are epithelial cells arranged in the parenchyma of the parathyroid gland?

as cords or clusters

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True or False: Chief cells are basophilic.

FALSE

eosinophilic

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What do the secretory granules of chief cells contain?

parathyroid hormone PTH

enclosed by secretory granules and liberated by exocytosis

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Describe the synthesis of PTH.

1) Ribosomes on the rER manufacture preproparathyroid hormone
2) Split as it is carried to rER lumen to form proparathyroid hormone and polypeptide
3) When it enters the golgi, it is split again to parathyroid hormone and polypeptide

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What is the function of oxyphil cells?

function unknown

may be dormant, inactive chief cells

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How do oxyphil cells stain?

intensely eosinophilic [due to mitochondria]

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Which is larger: chief cells or oxyphil cells?

oxyphil cells

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What is the function of intermediate cells?

function unknown

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What are the three cell types found in parathyroid glands?

chief cells, oxyphil cells and intermediate cells

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Is PTH essential for life?

Yes

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What does PTH regulate?

calcium and phosphate levels in the blood

[ * it increases blood calcium level, and simultaneously decreases serum phosphate]

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What do gland cells detect?

calcium

gland cells have calcium-sensing receptors

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How do low levels of serum calcium affect PTH? high levels of calcium?

low serum Ca 2+ –> stimulate release of PTH

high serum Ca 2+ –> inhibit release of PTH

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How does PTH influence bone?

PTH attaches to osteoblast receptors
casuses osteoblasts to release osteoclast simulating factor which triggers osteoclast activity
therefore, frees calcium from bone to enter the bloodstream

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How does PTH influence kidneys?

PTH prevents calcium loss in the urine

PTH promotes phosphate loss in the urine

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How does PTH influence the GI tract?

By regulating the formation of vitamin D in the kidneys

PTH controls the rate of calcium absorption from the GI. Vitamin D facilitates Ca 2+ absorption from the GI

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How do PTH and calcitionin work together?

PTH increases low calcium levels in the blood to normal

Calcitonin decreases elevated calcium levels in the blood to normal

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Why can’t surgeons completely remove the parathyroid glands?

Complete removal of the parathyroid glands will drop blood calcium level. This will cause tetanic contraction of muscles, including the laryngeal and respiratory muscles —> death

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Describe the connective tissue capsule of the pancreas.

The capsule gives rise to septa which 1) partition the gland into poorly defined lobules and 2) carry blood vessels, lymphatic vessels, and gland ducts

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What does the exocrine portion of the pancreas produce?

digestive enzymes

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What does the endocrine portion of the pancreas produce?

hormones

Where are islets of Langerhans found?

in the endocrine pancreas

What are the 5 cells found in the islets of Langerhans?

``` Alpha cells Beta cells Delta cells G cells PP cells (F cells) ```

How can the different cells int eh islets of Langerhans be differentiated?

immunocytochemical procedures

What hormone is associated with alpha cells?

Glucagon

What does glucagon affect?

Affects liver, skeletal muscle, and adipose tissue Increases blood glucose levels

What hormone is associated with beta cells?

Insulin

What is the function of insulin?

Decrease blood glucose levels

Somatostatin is associated with which cell in the islet of Langerhans?

Delta cells

What is the function of somatostatin?

Reduces smooth muscle contraction of digestive tract and gallbladder

G cells are associated with ....

Gastrin

Which hormone stimulates synthesis of HCl by parietal cells in the stomach mucosa?

Gastrin

What is associated with PP (F) Cells?

Pancreatic Polypeptide

What does pancreatic polypeptide do?

inhibits pancreatic exocrine secretions

What are the two potential causes of diabetes?

1) beta cells do not produce insulin | 2) defective insulin receptors on target cells

What may happen with uncontrolled diabetes?

``` stroke blindness myocardial infarcts circulatory disorders renal failure gangrene ```

Describe Type I diabetes.

``` insulin-dependent juvenile onset (less than 20 yo) ```

What are three signs of diabetes type I?

polydipsia (excessive thirst) polyphagia (excessive eating) polyuria (excessive urination)

Describe Type II diabetes.

non-insulin-dependent most common type usually affects individuals over 40 yo

What are the two regions of the adrenal glands?

Cortex (outer) | Medulla (inner)

Which region of the adrenal glands is larger?

Cortex makes up about 90% of the organ

What does the cortex produce?

corticosteroids

What does the medulla produce?

catecholamines (epinephrine and norepinephrine)

Which region is functionally associated with the sympathetic nervous system?

Medulla

What are the three zones of the cortex?

Outer --> inner | Zona glomerulosa, Zona fasciculata, Zona reticularis

What type of cells are found in the zona glomerulosa?

columnar cells arranged in cords and clusters

Describe the cytoplasm in the zona glomerulosa?

ACIDOPHILIC cytoplasm abundant sER, mitochondria GA, rER, lipid droplets, and free ribosomes

What do the cells in the zona glomerulosa synthesize?

mineralcorticoid hormones

What is the main mineralcorticoid hormone synthesize in the zona glomerulosa?

Aldosterone

What is the target and function of aldosterone?

Target: distal convoluted tubule of the kidney Function: stimulate water balance, absorption of sodium and excretion of potassium

What is the largest layer of the cortex?

zona fasciculata

What type of capillaries are found in the zona fasciculata?

sinusoidal capillaries

What type of cells are found in the zona fasciculata and how are they arranged?

spongiocytes are arranged in radial columns with sinusoidal capillaries running in between them * referred to as spongiocytes because the lipid droplet impart a foamy appearance

What organelles are abundant in the zona fasciculata?

abundant sER, golgi, mitochondia, lipofuscin pigment

What do the cells of the zona fasciculata synthesize?

glucocorticoid hormones: hydrocortisol and corticosterone

What is the function of hydrocortisol and corticosterone?

fucntion in control of carbohydrate, fat, and protein metabolism

What causes Cushing's syndrome (hyperadrenocorticism)?

small tumors of the basophils in the anterior pituitary gland producing excess ACTH with over stimulates the suprarenal cortex leading to excess cortisol production

What are the symptoms of Cushing's syndrome?

obese, mainly in the face, neck and trunk Impotency in males Amenorrhea in females

How does the zona reticularis look histologically?

intensely acidophilic | cells contain lipfuscin pigment

How are cells arranged in the zona reticularis?

cells form anastomosing cords

What do the cells of the zona reticularis synthesize?

weak androgens: dehydroepiandrosterone and androstenedione

What is the suprarenal medulla derived from?

neural crest

True or False: the suprarenal medulla is described as a modified sympathetic ganglion.

True

What two types of cells are found in the suprarenal medulla?

chromaffin cells and sympathetic ganglion cells

What are chromaffin cells?

modified neurons which form cords or clusters

What do chromaffin cells synthesize?

catecholamines: epinephrine and norepinephrine

True or false: catecholamines are responsible for the parasympathetic response.

FALSE | catecholamines are responsible for the sympathetic "fight or flight" response

Which cells in the medulla receive axon terminals of preganglionic sympathetic neurons of splanchnic nerves?

chromaffin cells - the neurons release Ach - chromaffin cells are equivalent to postganglion sympathetic cells but have no dendrites or axons

Where are sympathetic ganglion cells located?

In connective tissue of the medulla

Where do sympathetic ganglion cells send their axons?

Send their axons to the cortex where they modulate cortical activity and innervate blood vessels