Human Physiology Module 4

What hormones are involved in formation of osteoclasts?

PTH and Vit. D

What do osteoblasts secrete when they are not increasing blood Ca levels?

OPG

When RANKL is present what occurs to Ca levels?

increase due to resorption by osteoclasts

What do osteoclasts use to perform bone resorption?

hydrochloric acid

What is released when bones undergo resorption by osteoclasts?

Ca and PO4

What does PTH do to PO4 levels?

releases through the urine

What does calcitonin do to osteoclasts?

inhibits resorption by osteoclasts

What does estrogen do for the whole system?

support osteoblasts by reactivation of OPG

What are osteocytes?

osteoblasts that became trapped in bony matrix during bone formations

What releases FGF-23?

osteocytes

What is the function of FGF-23?

decrease Vit D → more PO4 secretion

What is able to activate Vit D in the kidney?

1-α hydroxylase

What are other names for active Vit. D?

1,25-dihydroxycholecalciferol

calcitriol

How does growth hormone affect bone?

elongates through IGF-1

How does cortisol affect bone?

breaks bone down

PTH affect on kidney:

reabsorbs calcium and releases phosphate

PTH affect on gut:

little to not affec

PTH affect on bone:

bone resorption

What inhibits PTH when blood plasma level has increased to normal levels?

1,25-Dihydroxycholecalciferol

Vit D affect on bone:

bone resorption and formation

Vit D affect on gut:

Ca and PO4 increase

What percent of circulating calcium is ionized (free)?

50

What percent of circulating calcium is bound to albumin?

40

How will hypercalcemia affect action potentials?

increase threshold

Why are PO4 and Ca always found together?

form strong biochemical attraction due to opposite polarities

If PO4 reabsorption is decreased, what occurs to ionized calcium levels in blood?

increased levels

Where is a majority of calcium found?

bone

What is the function of OPG?

inhibit osteoclast formation

What is the first site where vitamin D begins to be activated?

Liver

What do the beta cells of the pancreatic islets secrete?

insulin

What do the alpha cells of the pancreatic islets secrete?

glucagon

What do the delta cells of the pancreatic islets secrete?

somatostatin

What do the polypeptide cells of the pancreatic islets secrete?

pancreatic polypeptide

Insulin is formed from two chains, A chain of 21aa and B chain of 30aa. T/F

True

What is cleaved out during packaging to form insulin?

C peptide

How does glucose enter the beta cells?

via GLUT2

What channels close when glucose enters?

K channels

What is the result of K channels closing when glucose enters?

depolarization of cell

Due to the depolarization from K channels closing, what other channel opens, producing insulin?

Ca channel

Which has a greater effect on insulin, injected glucose or ingested glucose?

Ingested glucose

Cortisol and glucagon are what type of factors for insulin secretion?

stimulatory

How can sympathetic nervous system regulation decrease insulin?

through release of α2-adrenergic R

What does α2-adrenergic R do?

decrease insulin to increase blood glucose

What do B-agonists do?

decrease/oppose insulin effects

What do B-blockers do?

increase insulin effects

What are some insulin effects on liver?

increase glycolysis

Increase lipogenesis

increase TAG storage and export(VLDLs)

Which autonomic innervation stimulates insulin secretion?

parasympathetic

Which autonomic innervation inhibits secretion of insulin?

sympathetic

What does GLP-1 do?

increase secretion of insulin via G-protein pathway

What does GLP-1 do to blood level?

decrease blood glucose

DPP inhibitor will do what?

enhance insulin secretion

What does insulin do in the muscle?

ALL of the above

On which of the following are the GLUT 2 insulin independent receptors?

liver

Where are the GLUT 4 insulin dependent receptors?

adipose and muscle

Where is LPL stimulated when insulin is high?

adipocytes

What is best described by autoimmune destruction of beta cells?

Type 1 diabetes mellitus

What is best described insulin resistance and is usually self inflicted?

Type 2 diabetes mellitus

Which diabetes is more prone to metabolic acidosis/ketoacidosis?

Type 1 diabetes mellitus

Hyperglycemia is a key characteristics of diabetes mellitus? T/F

True