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BIOM3200 > 8. Endocrinology of calcium and phosphate homeostasis > Flashcards

8. Endocrinology of calcium and phosphate homeostasis Flashcards

1
Q

What is the significance of calcium phosphate for bones? - 2

A
  1. provides the structural integrity of the bone
  2. Ca phosphate is stored in bones and the bone is broken down when its needed for other biochemical processes
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2
Q

What are 5 biochemical processes that require Ca ions? - 5

A
  1. neuromusculat excitation
  2. blood coagulation (clotting of blood when injured)
  3. hormone secretion
  4. enzyme activity
  5. fertilization
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3
Q

T or F - Ca is tightly regulated w/in the body due to how essential it is for metabolism

A

T

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4
Q

a) in what form is Ca stored w/in the body
b) fill in the blanks = Ca__(PO4)__(OH)__

A

a) hydroxyapatite
b) 10, 6, 2

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5
Q

Within soft tissues where is Ca stored? Which one has the least Ca storage? Why? - 3

A
  1. intracellular
  2. extracellular - least b/c it is tightly regulated thus is easier to regulate it when its w/in the cell then we it is free floating in the matrix
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6
Q

What are the 3 forms that extracellular Ca takes? Assign the following percentages to each.
a) 40%? - 1
b) 50%? - 1
c) 10%? - 2

A

a) protein-bound
b) ionized (free)
c) combined w/ phosphate + citrate

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7
Q

What are the 3 types of membranes that cellular Ca are associated w/? - 3

A
  1. mitochondria
  2. plasma mem (mem of the whole cell)
  3. endoplasmic reticulum
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8
Q

T or F - Ca is essential for life thus in order to keep it properly regulated it is only stored intracellularly until its needed

A

F - extracellular Ca does exist but it is still tightly regulated

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9
Q

Total body Ca is maintained by the following. Explain each.
a) intake
b) output

A

a) diet = is absorbed via the small intestines which is regulated by hormones
b) kidneys = the Ca that is not used up is sent to the kidneys where it is urinated out

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10
Q

T or F - while the body is able to produce Ca it is not very efficient at it thus is it better to get it from ones diet

A

F - body cannot produce Ca

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11
Q

a) where is Ca mainly stored? - 1
b) how does it get there? - 2
c) how is Ca produced? - 2
d) Where does it go if its not being used? - 2

A

a) bones
b) using the ECF (extracellular fluid) or plasma
c) absorption through diet via small intestines
d) kidneys where its filtered out through urine

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12
Q

If you are deficient in Ca where are the 2 places that it will be pulled out? Which one is the main source? - 3

A

a) bones or kidney
b) bones

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13
Q

Why is there a constant movement of Ca w/in the body? - 2

A

is meant to distribute the proper ratios of Ca throughout the body in order to keep it stable

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14
Q

What are the 3 hormones that regulate the movement of Ca? Which ones are essential for adults? - 5

A
  1. PTH (parathyroid hormone) (sig for adults)
  2. vit D3 = calcitriol (sig for adutls)
  3. Calcitonin
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15
Q

the PTH is very essential for Ca so if you were to remove the thyroid gland what would occur? - 2

A

it will not necessarily lead to death as long as you keep the parathyroid gland which is the part of the thyroid gland that produces PTH.

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16
Q

Match the following parts of the larynx to the colours on this image
a) parathyroid glands
b) thyroid gland
c) trachea

A

a) green
b) blue
c) yellow

17
Q

What are the 2 cells in the parathyroid? Include their fxns - 4

A
  1. chief cells = produce PTH
  2. oxyphils = unkown
18
Q

Ans the following wrt the PTH
a) what tissue/organ produces it? - 1
b) what is its main fxn? - 1

A

a) the parathyroid gland
b) it raises Ca in the blood when plasma Ca levels are low

19
Q

a) What are the 3 mechanisms used to raise Ca in the blood?
b) which one is the primary mech?
c) what hormone raises Ca in blood?

A

a)
1. stimulate osteoclasts to resorb bone (break down)
2. stimulate kidneys to resorb Ca
3. activate Vit D (stim from kidney) which promotes the absorption of Ca by the intestines
b) 1
c) parathyroid hormone = PTH

20
Q

Describe the following terms wrt calcium phosphate homeostasis via the PTH
a) hypocalcemia - 2
b) hypercalcemia - 2

A

a) when Ca levels are too low resulting in INC secretion of PTH to bring it back up
b) when Ca levels are too high resulting in DEC secretion of PTH to bring it down

21
Q

What form does calcium take when stored in bone?

A

hydroxyapatite

22
Q

Describe the following cells wrt storage of Ca in bones
a) osteoblasts
b) osteoclasts

A

a) builds up Ca in the bones so it can be stored
b) breaks down bone in order to resorb Ca

23
Q

Match the following
a) osteoblasts
b) osteoclasts
1. Hydroxyapatite -> calcium phosphate
2. calcium phosphate -> hydroxyapatite

A

a) 2
b) 1

24
Q

Describe the 2 ways that stimulating the kidneys results in Ca resorption in the blood - 5

A
  1. the kidney itself contains Ca that would normally be disposed of through urine but can be resorbed b/f that occurs
  2. the kidneys produce enzymes that activate vit D3. Vit D promotes absorption in the intestines allowing more absorption of Ca from food/drink
25
Q

Put the following molecules in order wrt how the kidneys promote intestine absorption - 6
a) INC Ca
b) 1,25-dihydroxyvitamin D3
c) 25-hydroxyvitamin D3
d) intestinal absorption
e) INC 1alph-hydroxylase activity
f) DEC ca

A

f -> e -> c -> b -> d -> a

26
Q

Where is the inactivated form of Vit D3 found in the body? - 1

A

the liver

27
Q

Put the following in order wrt the production/intake of Vit D3. Describe the 5 steps
a) kidney
b) fish/meat
c) 7-Dehydrocholesterol
d) cholecalciferol
e) 1,25-dihydroxyvitamin D3
f) 25-hydroxvitamin D3
g) sunlight
h) liver

A
  1. our skin absorbs the g converting c -> d also known as vit D3
  2. h takes both d + vit D3 from the ingestion of b
  3. h convert d -> f
  4. the a converts f -> e
  5. e maintains the Ca homeostasis
28
Q

T or F - most production of Vit D comes from the ingestion of fish and meat

A

F - most comes from sunlight hitting the skin

29
Q

Which of the following is the active from of Vit D3
a) 25-hydroxyvitamin D3
b) Cholecalciferol
c) 1,25-dihydroxyvitamin D3
d) 7-Dehydrocholesterol

A

c

30
Q

What are the 2 fxns of Vit D3 - 3

A
  1. promoting intestinal absoption for Ca
  2. promoting formation of osteoclasts which resorbs bone (break down)
31
Q

ANS the following wrt calcitonin
a) where is it produced?
b) what type of Ca levels does it respond to (high/low)
c) What is it?
d) What is its fxn?
e) it appears to play a minor role in humans. How do we know this?

A

a) parafollicular cells of thyroid gland
b) high
c) a hormone
d) reduces Ca levels
e) if the thyroid gland is removed patient does not become hypercalcemic (high Ca in the blood) thus proving it not to be essential

32
Q

Draw a flow chart of how Calcitonin maintains Ca homeostasis. Include the following terms; bone, DEC Ca, INC Ca, neg feedback, Kidneys, inhibition of breaking down, calcitonin, stimulation of excretion, parafollicular cells, urine

A
33
Q

T or F - phosphate metabolism is controlled in an exact way as Ca due to them always remaining together

A

F - similar control but not as tightly monitored

34
Q

Describe the following wrt the parathyroid. Include what it causes
a) hyperparathyroidism - 5
b) hypoparathyroidism - 4

A

a) when the parathyroid is too active
- hypercalcemia (INC plasma Ca levels)
- INC bone resorption (break down too much)
- mineralization of soft tissues (resorption)
- INC thirst due to INC urination
b) when the parathyroid is under active
- hypocalcemia (DEC plasma Ca levels)
- ataxia = muscular weakness
- cardiac arrhythmias

35
Q

describe the 2 following disorders of Vit D
a) rickets - 3
b) osteomalacia - 3

A

a) low vit D in children causing bone pain, stunted growth, and deformities
b) low vit D in adults causing reduction of bone quality due to excess reabsorption (break down)

36
Q

What are the 3 risk factors for osteomalacia (bone brittleness)

A
  1. low Ca diet
  2. lack of exercise
  3. females a/f menopause
37
Q

Match the following w/ the image. How do you know
a) osteoporosis
b) normal

A

a) right
b) left
- much more bone loss in the right than the left

38
Q

What are the 3 treatments for osteoporosis (bone brittleness). Which one is the best

A
  1. INC Ca intake
  2. hormone therapy = PTH or calcitonin
  3. prevents = exercise, vit D + calcium intake (best)

BIOM3200 (18 decks)

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