basics of endocrinology

A hormone derived from cholesterol is likely to be:

• Lipophilic

• A steroid

You suspect that an endocrine gland is secreting too much hormone and this hormone is physiologically suppressed by a "factor" produced by the target organ of this hormone. If you  administer this "factor" intravenously to test the endocrine organ and the hormone does not decrease - what is that telling you?

The endocrine gland seems refractory to negative feedback

If higher than normal levels of insulin are required to move glucose inside the cells in a 9-year-old Quarter Horse mare, this will be an example of: 

tissue resistance

what are the 4 types of hormone transport methods

• autocrine

• intracrine

• paracrine

• endocrine

What are the 3 types of hormones

• steroids

• proteins

• amines

you track the path of an unknown hormone and it stops right outside the cell membrane and is unable to pass through this means the hormone is what

hydrophillic

which one is faster acting lipophilic or hydrophilic hormones

hydrophilic

what types of hormones use a second messenger

hydrophilic hormones

are steroid soluable in plasma

no

lipophilic hormones must do what in order to travel through the plasma 

bind to a protein 

what is hormone clearance determined by

• rate of synthesis and secretion

• rate of removal from circulation

what form of the thyroid hormone is active

T3

almost 99% of thyroid in the blood is __________

bound to proteins

is thyroid hormone regulated by positive or negative feedback 

negative feedback 

What is the main function of thyroid hormone

it increases metabolic activity

what enzyme turns t4 into its active form

deiodinases

what mineral is essential for Thyroid hormone secretion

Iodine

where is the target of thyroid hormones on cells

nuclear receptors

who has more thyroid hormones older or younger animals

younger

in the cold do you have more or less thyroid hormones

more

what does the hypothalamus regulate

• thirst

• body temp

• posterior/anterior pituitary secretion

where are the cell bodies of the posterior pituitary located

in the hypothalamus

how doe the posterior and anterior pituitary glands communicate with the hypothalamus

anterior = vascular

posterior = neural

does the posterior pituitary synthesize hormones

no

what hormones does the posterior pituitary secrete

• oxytocin

• vasopressin

for the hypothalamus and anterior list the releasing hormone and the resulting pituitary hormone (releasing hormone → pituitary hormone)

GnRh → FSH, LH

TRH → TSH

CH → ACTH

PIH → prolactin

GHRH → GH

what are the secretory granules that travel down to the posterior pituitary gland

Herring bodies

where are hormones released from the anterior pituitary gland

the median eminence

what is hydroxyapatite made of

• calcium

• phosphorus

• magnesium

for calcium found in extracellular fluid what is the breakdown by type

• ½ are protein bound

• ½ are ionized calcium

what 3 hormones regulate calcium 

• PTH

• Calcitonin

• Vitamin D

what are the 3 primary body systems that interact with calcium

• kidney

• intestine

• bone

how many parathyroid glands do mammals have

4

what are the 3 cell types of parathyroid glands

• chief cells

• clear cells

• oxyphil cells

which of the 3 cell parathyroid gland cell types secretes the most PTH

chief cells

What are the general functions of PTH in the kidney

• increase ca reabsorption

• decrease P reabsorption

• increase active vitamin D synthesis

what are the general functions of PTH in the bone

• increase bone resorption 

• turn osteoblasts into osteoclasts

what are the general functions of calcitonin on the kidney- 

• decrease calcium reabsorption

what are the general functions of calcitonin on the bone

• decreases bone resorption

what are the general functions of vitamin D on the kidney and intestine

increase calcium and phosphorus absorption and reabsorption

If you were to see high PTH levels and you wanted to reduce them what would you administer to the animal

Vitamin D

You get tests back showing an animal is insufficient in active vitamin D what hormone would you supplement to increase active vitamin D

PTH

Hypocalcemia stimulates what hormone to be secreted

PTH

Hypercalcemia stimulates what hormone to be secreted

Calcitonin

Vitamin D is activated in the ________ by __________

• kidney

• 1 alpha hydroxylase

what cells secrete calcitonin

Thyroid parafollicular cells

PTH related protein (PTHrP) works through what _________

PTH receptors