Chapter 16 - Endocrine Control Of Calcium Metabolism

Front 1

Majority of Calcium is in __________ form within __________ and ___________

Back 1

crystaline form in skeleton and teeth

Front 2

Functions of ECf Calcium (5)

Back 2

1. neuromuscular excitability

2. contraction-excitation coupling in smooth and cardiac muscle

3. stimulus-secretion coupling

4. maintenance of tight junctions b/w cells

5. blood clotting

Front 3

Neuromuscular excitability

1. minor fluctuation in free ECF Ca2+ has _____________________

2. fall in free Ca 2+ results in

3. rise in free Ca2+ ____________

4. decreases in free Ca2+ _____________

Back 3

1. has immediate impact on tissue excitability

2. overexcitability of nerves and muscles

3. decreases neuromuscular exciability

4. increases Na+ permeability - influx of Ca brings membrane to threshold

Front 4

Hypecalcemia causes skeletal muscle ______________

Back 4

to contract spontaneously

Front 5

Hypercalcemia can cause

Back 5

cardiac arrhythmia and depression of neuromuscular activity

Front 6

Excitation-contraction coupling in smooth and cardiac muscle

1. entrance of Ca2+ into smooth and cardiac muscle causes ...

2. increase in cystolic Ca2+ within a muscle cell causes

Back 6

1. action potential and triggers the contractile mechanism

2. neuromuscular excitability

Front 7

Stimulus secretion coupling

1. entry of ECF Ca2+ in secretary cells (ex. endocrine and nerve cells)

Back 7

causes release of neurotransmitter catecholamines

Front 8

Maintenance of tight junction between cells

1. Ca2+ forms a part of the

Back 8

intercellular cement that holds particular cells tightly together

Front 9

Blood clotting

1. Ca2+ serves as

Back 9

clotting factor

Front 10

What is hypocalcemia?

Back 10

Low plasma Ca2+ levels

Front 11

PTH (parathyroid hormone)

1. effect on Ca

2. why does it do what it does to Ca

3. absence of PTH

4. PTH effect on PO4

Back 11

1. maintain Ca homeostasis and balance

2. increase Ca plasm conc. to prevent hypocalcemia (by acting on bone, kidneys and intestines)

3. absence of PTH causes spasm of respiratory muscles due to asphyxiation

4. PTH lowers plasma PO4 conc

Front 12

Action of PTH on the BONE

1. PTH uses bone as ________ to ___________

2. induces _______

3. stimulates

Back 12

1. uses bone as bank to withdraw Ca as need to maintain plasms Ca level

2. induces fast Ca efflux into plasma from calcium pool in bone fluid

3. stimulates bone dissolution - thus releasing Ca, Po4 and bone minerals to plasma from bone itself

Front 13

How does PTH mobilize Ca from labile and stable pool in bone (3)

Back 13

1. PTH activate membrane bound Ca pump located in membrane of osteaocytic-osteoblastic bone membrane

2. this pump promotes movement of Ca from bone fluid to plasma

3. PTH draws Ca out of bone bank and increases Ca level without breaking done mineralizeed bone itself

Front 14

1. Fast exchange of Ca from bone to plasma

2. Slow exchange of Ca from bone to plasm

Back 14

1. through PTH-activated Ca channels on osteocytic-osteoblastic membrane

2. osteoclast dissolution of bone

Front 15

PTH causes bone dissolution by

Back 15

1. stimulating osteoclast

2. inhibiting bone forming activity of osteoclast

3. promotes dissolution of Ca - phosphate crystals in bone

Front 16

Prolonged excess PTH over month/years can cause formation of

Back 16

cavities in skeleton

Front 17

Action of PTH on kidneys

1. stimulate Ca2+

2. promotes PO4

Back 17

1. Ca conservation during urination 0 cuases kidneys to reabsorb Ca to prevent loss of Ca in urine (increases plasma Ca)

2. promotes PO4 elimination during urinaiton by decreasing reabsorption of PO4 by renal tube (decreases plasma PO4)

Front 18

Action of PTH on the intestine

1. indirectly ____________ Ca

Back 18

indirectly increases Ca and PO4 absorption from the small intestine by (PTH) activating Vitamin D (vitamin D directly increases intestinal absorption of Ca and PO4)

Front 19

Calcitonin serves as ... and is prouced by...

Back 19

- calcitonin serves as back up during rare times of extreme hypercalcemia

- is produced by C cells from the thryoid gland

Front 20

Calcitonin effects on bone

1. SHORT TERM:

2. LONG TERM:

Back 20

1. decreases Ca movement from bone fluid to plasma

2. decreases bone absorption by inhibiting osteoclasts

Front 21

What stimulates the release of calcitonin?

Back 21

gastrointestinal hormones secreted during digestion

Front 22

Calcitonin VS PTH

Back 22

Calcitonin: works during times of hypERcalcemia and decreases plasma Ca2+

PTH: works durings times of hypOcalcemia and increases plasma Ca

Front 23

Effects of vitamin D (2)

Back 23

1. increase Ca absorption in intestine - more Ca absorbed into plasma

3. increases responsiveness of bone to PTH