Endocrine System 12/1

Insulin is released when blood glucose levels are (low/high).

high

How does insulin allow blood glucose levels to fall?

1) Accelerates the facilitated diffusion of glucose into cells by way of the glucose T4 transporter. 2) Increases the rate of glycogenesis (glycogen formation). 3) Increases uptake of amino acids and rate of protein synthesis. 4) Increases rate of lipogenesis (fatty acid synthesis). 5) Decreases rate of glycogenolysis. 6) Decreases rate of gluconeogenesis.

Explain the calcium-blood level regulation by the thyroid and parathyroid. Do not go into detail how the hormones work. Start with high concentration of calcium in blood.

1) High Ca2+ in blood stimulates the parafollicular cells of the thyroid gland to release more calcitonin. 2) Calcitonin inhibits osteoclasts, thus decreasing blood calcium levels. 3) Now that blood calcium level is low, the chief cells of the parathyroid are stimulated to release more PTH. 4) PTH increases osteoblast activity and number, decreases loss of calcium to the urine, and finally stimulates the kidney to release calcitriol. 5) Calcitriol can then increase calcium absorption in the gut. *** If the blood calcium level gets too high again, the process repeats.

Name the functions/actions of cortisol.

1) Stimulates protein breakdown so the amino acids can be used to make new proteins or ATP. 2) Stimulates gluconeogenesis. 3) Lipolysis to make fatty acids which can be made to form ATP. 4) Provides resistance to stress by increasing the body's glucose supply to make ATP. 5) Makes blood vessels more sensitive to other hormones that cause vasoconstriction. 6) Anti-inflammatory effect. 7) Makes you feel jittery at high doses. 8) Depresses the immune response by inhibiting T-cells

What is the normal blood glucose level.

70mg/100ml of blood

What is the normal blood level of Calcium?

9-11 mg/100ml of blood.

What does PTH do?

Acts to increase blood calcium levels in three ways: 1) Increases osteoclast number and activity. 2) Decreases the loss of calcium from the blood to the urine. 3) Stimulates the kidneys to release calcitriol.

What endocrine gland is vital to our survival because of its role in maintaining fluid and electrolyte balance?

Adrenal Gland

Is the pancreas an exocrine or endocrine gland?

Both!

Where does calcitriol come from?

Calcitriol is the active form of vitamin D3 which is created by the skin from cholesterol.

If the amount of calcium in the blood increases dramatically, how does this affect the neurons?

Can prevent repolarization.

What are three macroscopic layers of the adrenal glands?

Capsule (most superficial, yellow covering), Adrenal cortex, adrenal medulla.

What are the two main cells in the parathyroid? What do each do?

Chief cell (secretes PTH), Oxyphil cell (we don't know what it does).

What does the adrenal medulla secrete? By what cells?

Chromaffin cells secrete E and NE.

Why are drugs like cortisol necessary and important for organ transplants?

Cortisol decreases the immune response which will make the person less likely to reject the newly implanted organ.

How does cortisol cause an anti-inflammatory effect?

Cortisol inhibits those WBC's that participate in the inflammatory response.

In rheumatoid arthritis, the immune system attacks joints causing swelling and pain. How can this be treated?

Cortisol! It inhibits those WBC's that participate in the inflammation, decreasing swelling, decreasing pain.

How are blood pressure and blood volume related?

Directly!

Why do women get osteoporosis?

Estrogen binds to osteoclasts and inhibits their action. This prevents bone resorption. When women start producing less estrogen, osteoclast activity increases (because they are being inhibited less) and this causes rapid bone loss (osteoporosis).

What three drugs can be given to osteoporosis patients to decrease the rate of bone resorption? How do these drugs work?

Evista (acts like estrogen in that it binds to osteoclasts and keeps them in check), Fosamax and Actonel (decrease osteoclast activity by entering the osteoclasts and destroying them).

What kinds of activities are considered "stressful" enough to cause in increase in cortisol production?

Exercise, fasting, temperature extreme, trauma, etc.

What does calcitonin do?

Inhibits osteoclast activity so that they don't break down more bone and send it to the blood. In this way, calcitonin decreases the concentration of Ca2+ in the blood.

What happens when insulin is secreted into the blood?

Insulin binds to a tyrosine kinase. This causes a Glucose T4 transporter to be inserted into the plasma membrane. This allows glucose to be uptaken by the cell. As the glucose enters the cell it is immediately phosphorylated so that the glucose gradient does not become unfavorable to influx.

Describe the conformational structure of insulin.

It is a 51 aa protein consisting of 2 aa chains joined by a disulfide bond.

How does cortisol cause an increase in blood pressure?

It makes the blood vessels more sensitive to hormones that cause vasoconstriction. This increases blood pressure.

What does calcitriol do?

It stimulates the absorption of calcium in the digestive system. For calcium to be absorbed, calcium binding proteins must be present. Calcitriol promotes the formation of these calcium binding proteins which in turn increases calcium uptake and finally increases calcium levels of the blood.

Where is the pancreas?

Located near the C shape of the duodenum

Where are the adrenal glands?

On top of the kidneys.

Explain the obesity crisis.

People got scared of fats, turned to high carb diets. These increase blood glucose levels which cause insulin to be pretty high. Insulin promotes the storage of fat. This is how people got fat

If the doctor notices swelling and can't figure out where it is coming from, what might the doctor prescribe to take care of the swelling?

Prednisone (four tiems as potent as cortisol and decreases swelling by inhibiting the WBC's responsible for inflammatory response).

Draw an islet of Langerhans.

See p 27 of handout. Include exocrine acini with beta and alpha cells, and blood capillaries.

Where is the parathyroid gland?

Should actually read parathyroid glands (plural). These are little kidney bean shaped things in the back of the thyroid gland. (see p 22 of print outs)

Why do we have increased BP when we are stressed?

Stress causes cortisol production which increases blood pressure.

Name the layers of the adrenal cortex from superficial to deep. Name also what is secreted in each layer.

Superficial. Zona glomerulosa (secretes mineralcorticoids), Zona fasciculata (glucocorticoids), Zona reticularis (androgens).

The thyroid and parathyroid both work together to regulate the blood calcium levels. How do they do this and which does most of the work?

The chief cells of the parathyroid release PTH (parathyroid hormone) which is the main regulator of blood calcium levels. In addition, the parafollicular cells of the thyroid release calcitonin which also regulate calcium levels in the blood.

Not all organs are regulated by insulin via the glucose T4 transporter. Which organs are these and why do they behave differently?

The liver, Kidney, and Brain. They don't have a glucose T4 transporter, they have a Glucose T2 receptor which is always in the PM and always uptaking glucose whenever possible.

Some people work with radioactive iodine (iodine 125). What do these people do to prevent their thyroid from blowing up?

They take Iodine pills to saturate the blood with regular iodine so that the thyroid is less likely to take radioactive iodine up and self-destruct.

If your blood glucose level is 100mg/100ml of blood, name the hormone release by the pancreas and give its pathway of effect. (don't include specifically what insulin does to complete its objective, but state its objective and how the hormone's release is regulated).

This is a hyperglycemic state in which beta cells of the pancreas will release insulin. Insulin then does a whole bunch of stuff to make blood glucose levels fall. If they fall too much, hypoglycemia inhibits the release of insulin.

Describe the ratio of alpha cells to beta cells in the islets of Langerhans.

This is a small ratio as there are many more beta cells than alpha cells. (see p 27 of pic)

If you blood glucose level is 30mg/100ml of blood, name the hormone released by the pancreas and give its pathway of effect.

This is below normal blood glucose level so glucagon will be released by the alpha cells of the pancreas. Glucagon acts on the hepatocytes (liver cells), causing them to do glycogenolysis (break down glycogen into glucose) and gluconeogenesis (form glucose from lactic acid and certain amino acids). In this way, excess glucose is made in the hepatocytes which then shoot it into the blood, raising the blood glucose level. If the blood glucose level continues to rise, hyperglycemia inhibits the release of glucagon. (see p 28 of pics)

In what kinds of body situations doe the body produce cortisol?

When the body is under stress or trauma.

What is bone resorption?

When the osteoclasts breakdown bone matrix, releasing Calcium into the blood.

What cells secrete insulin in the pancreas? What cells secrete glucagon?

alpha cell (glucagon), beta cell (insulin)

The administrable form of cortisol is called (blank). But, there is a more potent form that can be given called (blank) which is (#) times as potent as cortisol.

cortisone, prednisone, 4

If the adrenal gland is not functioning properly we can die of...

dehydration and electrolyte imbalance.

The islets of Langerhans are 99% (exocrine/endocrine).

exocrine! 99% is the acini clusters which release digestive enzymes by exocrine.

The zona (glomerulosa/fasciculata) mainly secretes the mineralcorticoids (blank) while the zona (glomerulosa/fasciculata) mainly secretes the glucocorticoid (blank).

glomerulosa, aldosterone, fasciculata, cortisol

(glucagon/insulin) works mainly on the liver while (glucagon/insulin) has a widespread effect on almost the entire body.

glucagon, insulin

What endocrine hormones does the pancreas produce?

insulin, glucagon

What are the fundamental units of the pancreas.

islets of Langerhans

The (mineralcorticoid/glucocorticoid) aldosterone is important in maintaing the (blank) balance. Specifically if calcium levels of the blood (increase/decrease), the zona glomerulosa is stimulated to secrete aldosterone. By affecting this balance, aldosterone has an effect on both blood (blank) and (blank).

mineralcorticoid, Na/K, increase, pressure, volume.