Psl 535: Scribe #10 Adrenal Medulla

Front 1

The adrenal medulla is regulated by what system?

What hormones are secreted?

Back 1

Nervous system-innervated by sympathetic preganglionic fibers

Epinephrine and Norephinephrine

Front 2

What is the control of the adrenal medulla?

Back 2

A normal medullary (chromaffin) cell is activated by acetylcholine from a preganglionic sympathetic neuron. These medullary cells secrete catecholamines (epinephrine) into the blood.

Front 3

Conditions that stimulate adrenal medulla

Back 3

1. Stress
2. Hypoglycemia
3. Trauma
4. Cirulatory failure (hemorrhage)
5. Exercise
6. Illness
7. Hypoxia
8. cold exposure

Front 4

How is epinephrine synthesized?

Back 4

All catecholamines are formed from tyrosine.

Important step is conversion of NE to epi via enzyme PNMT which is activated by cortisol!!!

Front 5

What does epinephrine do during hypoglycemia?

Back 5

Epinephrine acts to restore glucose back to normal thru anti-insulin actions.

Front 6

Why are plasma NE concentrations higher than plasma EPI concentratio?

Back 6

This high NE is not from the adrenal medulla. This NE has been leaked into circulation by noradrenergic synapses.

So, EPI is a hormone while NE is a neurotransmitter bc its levels are not high enough to have biological actions.

Front 7

Metabolic actions of EPI

Back 7

Promote glucose outup by the liver:
1. gluconeogenesis
2. glycogenolysis
3. Lipolysis
4. Stimulation of glucagon secretion from pancreas
5. Inhibition of insulin secretion

Front 8

What are the counter-regulatory hormones (which respond to stress)

Back 8

1. cortisol

2. GH

3. EPI

4. glucagon

Front 9

Overall, during stress what ultimately happens?

Back 9

Causes insulin causing blood glucose to rise and provide free FA via glycogenolysis, gluconeogenesis, lipolysis

Front 10

Stress causes what to be released by the hypothalamus?

Back 10

CRH which leads to release of ACTH which causes an increase in cortisol

GHRH released by hypothalamus increases GH

Front 11

Stress causes what to be released by the nervous system?

Back 11

Increase in EPI, glucagon, and suppression of insulin

Front 12

What is the job of the parathyroid hormone (PTH)?

Back 12

To increase calcium during hypocalcemia.

Front 13

How does PTH inc. calcium into the blood?

Back 13

1. Bone: inc. bone resorption by release of calcium & phosphate

2. Kidney: Inc. calcium resorption from tubules, activation of vitamin D (require PTH)

3. Dec. phosphate reabsorption and more is excreted in urine.

Front 14

Ingested calcium can deposit where?

Back 14

1. Bone to mineralize it

2. Calcium is also filtered by the kidneys and the majority is reabsorbed back into the body.

Front 15

Positive calcium balance

Back 15

Occurs in young growing individuals who need a lot of calcium for their bones.

Front 16

Negative calcium balance

Back 16

Occurs in older individuals who may have osteoporosis and are losing a lot of bone mass

Front 17

Phosphate excretion is enhanced by what hormone?

Back 17

Parathyroid hormone (PTH)

Front 18

Vitamin D

How made?

Back 18

Steroid hormone

Made in skin from 7-dehydrocholesterol (cholesterol is a precursor)

In the liver it is modified (25 hydroxy group added)

Front 19

How is vitamin D activated?

Back 19

In kidneys, 1-hydroxylase adds hydroxy groups at 1 position forming 1,25 dihydroxy vitamin D.

Front 20

When is 1-hydroxylase stimualted?

Back 20

1-hydroxylase is the enzyme that puts OH group at 1 position forming 1,25 dihydroxy vitamin D.

Itis stimulated by an increase in PTH or a decrease in phosphate.

Front 21

The active formof vitamin D acts on tissues such as?

Back 21

Intestines
Bones
Kidneys (lesser extent)

Front 22

What does Vitamin D do to intestinal cells?

Back 22

Enhances calcium absorption from the gut by entering intestinal cells, binding to nuclear receptors, causing biological effects that get calcium and phosphate into cell.

Front 23

What does vitamin D do in the bone?

Back 23

Increases bone resorption (raising blood calcium)

Front 24

Function of osteoblasts

Back 24

Make new bone, and the matrix they make needs to be mineralized by calcium and phosphate.

Front 25

Function of osteoclasts

Back 25

Break down bone

PTH and vitamin D stimulate bone resorption

So release of calcium into ECF which can go into the blood.

Front 26

Disease caused by not enough vitamin D to allow mineralization of bone to make them strong.

Legs become bowed

Back 26

Rickets

Front 27

Parathyroid cells sense a decrease in calcium and release more PTH which does what?

Back 27

1. Mobilization of calcium from bone

2. Stimulate kidneys to make more 1-hydroxylase enzyme to activate vitamin D

3. Acts on kidney to reduce calcium excretion

4. Normalize calcium levels in plasma

Front 28

Job of calcitonin?

Back 28

Reduces calcium when calcium increases above normal

Inhibits bone resorption

Front 29

During high calcium levels there will be high calcitonin levels

Back 29

Hypercalcemia

Front 30

There is a balance between PTH and calcitonin

Back 30

Normal calcium range

Front 31

PTH levels will be high, and calcitonin goes down towards zero

Back 31

Hypocalcemia

Front 32

Clinical administration of calcitonin

Back 32

If calcium is high, administer calcitonin, eventually calcium returns to normal.

To maintain its effects, calcitonin should be administered chronically

Front 33

What are the symptoms of hypercalcemia for the kidney?

Back 33

1. Kidney stones (nephrolithiasis)
2. Polyurea
3. Polydypsia
4. Nocturia (urinating at night)
5. Renal failure

Front 34

What are the symptoms of hypercalcemia for the skeletal?

Back 34

1. Osteitis fibrosa cystica
2. Subperiosteal bone resorption
3. fractures

Front 35

What are the symptoms of hypercalcemia for the neuromuscular?

Back 35

Hyperpolarization of nerves
Hyporeflexia
Coma

Front 36

What are the symptoms of hypercalcemia for the gastrointestinal?

Back 36

Constipation

Front 37

Effect of chronic magnesium deficiency

Back 37

Can suppress PTH secretion which causes hypocalemia

Front 38

Mneumonic for hypercalcemia

Back 38

"Bones, stones, and groans"

Weak bones, kidney stones, and constipation

Front 39

High calcium (hypercalcemia) AND too much PTH causes?

Back 39

Hyperparathyroidism

Front 40

low calcium and low PTH causes?

Back 40

Hypoparathyroidism

Front 41

Muscle spasms due to excessive muscle contraction

Back 41

Hypocalcemic tetancy

Front 42

Tap on facial nerve, which if there is hypocalcemia will be more sensitive and facial muscle will go into spasm

Back 42

Chvostek's sign

Front 43

Blow up pressure cuff on arm, and the hypocalcemic hand will go into spasm

Back 43

Trousseau's sign

Front 44

Symptoms of hypocalcemia

Back 44

1. Hypocalcemic tetany: Chvostek's sign and Trousseau's sign

2. Brisk reflexes

3. Seizures

4. Paresthesia

Front 45

What is the treatment for hypocalcemia

Back 45

1. Calcium supplements
2. Vitamin D
3. PTH analog

Front 46

Vitamin D stimulates?

Back 46

Bone resorption

Front 47

Vitamin D excess is due to?

Back 47

High calcium & low PTH (compensating)

Front 48

Vitamin D deficiency is due to?

Back 48

Low calcium and high PTH (compensating)