Endocrine System Pt. 3 Flashcards
What does the thyroid gland consist of?
Two lopes that are located one either side of the larynx
What are the two lobes of the thyroid gland connected by
a narrow band called the isthmus - depend on the species
What is the appearance of the Thyroid gland
has thousands of tiny follicles
Each follicle contains a sphere which is made of what kind of cells
simple, cuboidal glandular cells
The sphere of the follicle surrounds what
a globule of the thyroid hormone precursor
the precursor in the globule is known as what
collide
The thyroid is the only gland that stores large amounts of _________
hormone precursor
What are the two products of the thyroid gland
thyroid hormone and calcitonin
what does the thyroid hormone regulate
regulates body’s metabolic rate
what does calcitonin regulate
regulates blood calcium levels
When the Thyroid-stimulating hormone from anterior pituitary stimulates the thyroid gland, two hormones are produced, what are they
T4 (tetraiodothyronine) thyroxine and T3 (triiodothyronine)
What is T4 considered
a prohomrone - inactive form
What is T3 considered
an active hormone
If T2 is the active form, what does T4 do?
Acts as a circulating reservoir
Converted to T3 in liver, kidney, and muscle when needed
What kind of effect does TSH have
Calorigenic effect
What does the calorigenic effect to
helps heat the body by regulating the metabolic rate of all cells (AKA how quickly they produce energy)
What do you think happens when a body is in a cold environment?
The body will increase thyroid production
Do you think there are any other environmental conditions that effect thyroid production?
Stress levels can decrease thyroid production
What is another function of TSH
Protein, carb, and lipid metabolism
What is the effect of TSH on protein, carb, lipid metabolism
Encourages anabolism
what is anabolism
protein synthesis
What would happen of a diet is insufficient in energy
Thyroid hormone would promote catabolism of energy stores
What does thyroid hormone prevent
hypoglycemia
What does the thyroid hormone promote
catabolism of lipids
Why do young animals need TH for normal growth and development
Influences development and maturation of CNS, Muscles, and Bones
What is calcitonin produced by
C cells found btwn thyroid follicles
Calcitonin is one of two hormones that regulate what
calcium levels
What does calcitonin prevent
hypercalcemia by promoting excess calcium to be deposited in bones
Where are the parathyroid glands found
they are several small, pale nodules found on, in, or near the thyroid glands
What does PT produce
PTH or parathyroid hormone
What is PTH’s function
Maintains calcium homeostasis - does the exact opposite of calcitonin
What happens if blood calcium levels get too low
PTH -> is released -> works on kidneys, intestines, bones -> increases circulating blood calcium levels
How does PTH wok on kidneys, intestines, and bones
Kidneys reabsorb CA
Intestines absorbs CA from food
Bones pulls out of the bank (osteoclasts)
Adrenal glands are located where
(Named for their location) near the kidneys at the cranial ends
The Adrenal glands looks like one single gland, but is actually two, why?
One wrapped around each other
What is the outer adrenal glland called
adrenal cortex
What is the inner adrenal gland called
Adrenal medulla
The adrenal coretx is responsive to what
ACTH
What 3 main hormone groups does the adrenal cortex make?
Glucocorticoids
Mineralocorticoids
Sex hormones
Glucocorticoids are named by effect on BG levels because they have what kind of effect
Have a general hyperglycemic effect
How do glucocorticoids cause hyperglycemic effect
several different mechanisms and catabolism of proteins and lipids -> get glucose from these from gluconeogenesis
What do mineralocorticoids regulate?
electrolytes in the body
The main mineralocorticoids hormone
aldosterone
what does aldosterone affect?
affects levels of sodium, potassium, and hydrogen ions
What do Mineralocorticoids target
kidneys
How do mineralocorticoids affect the kidney
cause sodium resorption in exchange for potassium
What does sodium resorption affect
water levels in the body because the water follows the sodium back
What sex hormones are produced by the Adrenal crotex
In males - androgens - and in females - estrogens - are produced in minute amounts so there is minimal effect
The adrenal medulla is derived from
nervous tissue - resembles it microscopically
The adrenal medulla has modified neurons that makes two similar hormones, wjich are
Epinephrine and noreponephrine
The adrenal medulla is under the control of
Sympathetic system
What is the two portions of the pancreae
endocrine and exocrine
endocrine portion is made of thousands of tiny clumps of cells scattered throughout the organ are called
Pancreatic Islets aka Islets of Langerhans
What are the three main cells of islets
Alpha, Beta, and Delta
What do alpha cells make
glucagon
What do Beta cells make
Insulin
What do Delta cells make
Somatostatin
Insulin and glucagon have important roles in what
metabolism and use of glucose, has opposite effect
Somatostatin inhibits what
the secretion of insulin and glucagon
Insulin is essential for life. What does it do
causes glucose, AA, and fatty acids in the bloodstream, to be absorbed through cell membranes
What is the overall effect insulin
Moves glucose out of the bloodstream into cells
acts to lower the level of glucose in the blood
Glucagon has what effect
hyperglycemic effect - opposite effect of insulin
What does glucagon stimulate to have the hyperglycemic effect
Stimulates the liver to convert glycogen to glucose
stimulates gluconeogenesis
Net effect is to raise the level of glucose in the blood ->B/c other hormones (GH and glucocorticoids) have similar effects so a deficiency in glucagon isn’t as severe as one in insulin
