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Metabolism-Alaa > Calcium > Flashcards

Calcium Flashcards

1
Q

Anatomy of parathyroid gland.

A

it is suseptible to being damaged during thyroid surgery

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2
Q

Cells of the parathyroid gland?

A

Cheif and Oxyphil cells

Chief (its the boss!)>> produce PTH

Oxyphil> no one cares?

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3
Q

what is Calcium?

what is normal serum calcium?

what is biologicall active free Ca levels?

A

-most abundant metal in our body

Normal serum calcium levels are 2.2-2.6 M

– biologically active free ionized [Ca2+] closely regulated to 1.0-1.3 mM

– Remained bound to plasma proteins or complexed with citrate

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4
Q

functions of Calcium?

A
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5
Q

unlike calcium, the plasma phosphate concentration is not very strictly regulated, and its levels fluctuate throughout the day, particularly after meals

A
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6
Q

what forms the hydroxyapatite crystals?

importance of the crystal?

A

Calcium and phosphate!

it is a major portion of the mineral phase of the bone!

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7
Q

Ca+ and phosphate r regulated by 3 hormones.

Name them and what organs do they act on to control these ions? (in order) (3)

A
  • PTH
  • Cacitrol
  • Calcitonin
  1. GI tract
  2. Bone
  3. Kidenys
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8
Q

actions of these hormones on calcium and phosphate are opposed …how?actions of these hormones on

A

a particular hormone may elevate the level of one ion while lowering that of the other.

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9
Q

where is most Calcium located?

A

In the bone!

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10
Q

the calcium in our bones is constantly being recycled round

cuz bone is a dynamic tissue

A

ok

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11
Q

typical daily dietry intake of Ca+?

major source of it?

A

800-1200mg

Dairy products

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12
Q

Describe the distribution of Ca+ in our body!

A
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13
Q

In plasma, Calcium exists in 3 physiochemical forms:

which form is the physiologically active form?

A

1) 45% free
2) 45% Bound to serum proteins (especially albumin)
3) 10% Bound to small organic anions (e.g., citrate and oxalate).
* Freeeeee*

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14
Q
A
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15
Q

Alkaline phosphatase

A

ALP is an enzyme made mostly in the liver and in bone with some made in the intestines and kidneys . It also is made by the placenta of a pregnant woman.

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16
Q

what effect does hypercalcemia have on the CNS?

what symptoms can result?

A

Normally in the neuron, the resting state of Na channels is stabilized by Ca+>> this prevents spontaneous depolarisation!

but in hypooo….

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17
Q

sometimes total Ca levels in the blood can vary a bit, depenidng on the blood’s PH & protein levels!

explain

A

during acidosis (LOW PH) , means theres alot of H+ ions floating around , albumin’s “Coo-“ groups pick up the protons and become COOH,

this makes it more positively charges and therefore repels Ca+!

*Free ioniz**ed calcium increases in blood!*

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18
Q

What hormones r involved in regulation of serum Ca2+?

A

Short term>> PTH

Long term>> active form of V.D (calcitrol)

lol. .
* they both raise serum Ca+!*

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19
Q

active form of Vitamin D? half life?

A

(calcitrol)

0.25days

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20
Q

what is VD?

how is it activated?

A

a collective term for a group of prohormones:

the two major forms of which are:

vitamin D2 (ergocalciferol) & vitamin D3 (cholecalciferol)

must undergo 2 hydroxylation reactions to be activated in the body>>>>Calcitriol (1,25- dihydroxycholecalciferol)

activated by PTH

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21
Q

where do we get our Vitamen D from?

A

Vitamin D obtained from sun exposure, food, and supplements, is biologically inert.

So it MUST undergo 2 hydroxylation reactions to be activated in the body.

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22
Q

functions of VD

A

– Increases intestinal absorption of dietary Calcium and renal

reabsorption of Calcium

– Increases bone resorption (breakdown of bone tissue to release calcium)

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23
Q

what 3 target organs does PTH act upon?

A
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24
Q

what is PTH

roles?

A
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25
Q

fucntions of PTH and calcitonin on maintaining calcium levels

A
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26
Q

what happens if Ca levels r low in the body?…

(what mechanism does body do to proper this?

A
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27
Q

how is PTH different from insulin?

A

insulin is made and stored

PTH is NOT stored

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28
Q

how is PTH synthesis produced and released?

A

when Ca+ binds to recepter (Gq) > slows down realease of PTH and its production

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29
Q

which region in the kidney does PTH have an effect on to release Ca+ levels?

A

Distal Tubule!

30
Q

what happens when our hydroxyapeptite is broken down?

A

they’re freeing calcium and phosphate, these 2 in high concentrations can form crystals>> and that is a problem in the kidenys!

soooo..

The kidney needs to reguale this..

when we increase the amount of calcium reabsorption in the kidenys( via PTH)

We also Increase the amount of Phosphate the kidney looses!

31
Q

How is calcium reabsorbed in the thick ascending loop of henle?

A
32
Q

what is PTHrP

A
33
Q

PTH action on the gut?

A

absorption is increased in the presence of VD!

Remember……..PTH stimulates conversion of vitamin D to its active form which ↑uptake of Ca2+ from gut.

34
Q

how does PTH act on bone?

A
  • increases bone turnover by increasing the activity of Osteoclasts! (via cytokines)
  • it decreases osteoblast activity
35
Q

Calcitonin?

A

released and produced by C cells (parafollicular cells) of the thyroid gland.

-

36
Q

if we remove the thyroid gland from a patient.(thyroidectomy) do they loose the ability to regulate serum Ca2+ levels?

Explain?

A

NO, cuz Calcitonin doesnt play a major role in Ca + homeostasis

37
Q

what is EDTA?

A

its a calcium chelator

it binds all the calcium in the blood

when u take a full blood count, u’ll put it in this bottle which contains EDTA, to let the blood clot

38
Q

ROle of calcium in the clotting cascade and VK

A

Vk adds a carboxyl group on the Gla domain of the promthrombin, this makes the gla super negative charged>> attracts Ca+ and on the other end calcium adheres to the platelet membrane at site of wound!

(so Ca+ acts like a bridge btw prothrombin and the platelet memebrane))

39
Q

when we want to give blood transfusion we obviously dont want the blood to clott in the transfusion bag.

what is contained in the bag to prevent this clotting from occuring?

A

it contains Citrate, which chelates Ca+,

& Ca+ is whipped out of this bag by the citrate> bag doesnt clot yay!

40
Q

calcium is clotting factor number____

A

4

41
Q

after giving a blood transfusion of about 5ooml of blood to a patient, why should we give the IV Ca+

A

cuz remember the bag had citrate which removed the calcium, and so the patient will not have any calcium after tranfused

42
Q

Hyper & Hypo calcemia effects

A
43
Q

Symptoms of hyper and hypo Calcemia

A

Hypocalcaemia

hyper- excitability in the nervous system,

paraesthesia>> tetany>> paralysis and even convulsions.

hypercalcaemia

kidney stones (renal calculi),

constipation>> dehydration

kidney damage>>tiredness and depression.

44
Q

when looking at Ca+ levels in the body, what value should u make sure you’re looking at?

A

Adjusted Ca+

(its adjusted for the ALBUMIN level)

45
Q

what are the 2 most common cause of HYPERCALCEMIA in a hospital setting?

A
  • Malignant metastases that have gone to bone & r osteolytic
  • Multiple myeloma
46
Q

what is multiple myeloma?

A

Multiple myeloma affects the plasma cells inside the BM.

47
Q

what r common causes of cancers that metastasise to bone causing lytic lesions and hypercalcemia?

A
  • Breast
  • lung
  • Renal
  • thyroid
48
Q

what is the commonest cancer in men? does it cause hypercalcemia?

A

Prostate cancer

no, it causes osteoblastic metastases that do not cause hypercalcemia

49
Q

what r the common sites for metasteses?

A
  • vertebrae
  • pelvis
  • proximal femur
  • ribs
  • proximal humerus
  • skull
  • (these r the sites that r particulary active in formation of RBC’s, so if uve got metastases, they would want to lodge at thea reas that have got good blood supply)*
50
Q

what is this xray showing?

A

osteoblastic activity

Metastatic prostate cancer

51
Q

what causes primary hyperparathyroidsim?

what can this lead to?

A

the parathyroid gland develops an Adenoma and secretes excessive PTH> which will increase osteoclastic activity> serum calcium levels rise (hypercalcemia)

52
Q

what causes secondary hyperparathyroidism

A

All 4 parathyroid glands become hyperplastic.

due to Vitamin D deficiency > this means that their Ca+ absorption is low resulting in low serum Ca+ levels,

parathyroid gland go hang on? we need to make more Ca+! > PTH levels to rise.> activates osteoclasts> in an attempt to maintain normal serum calcium

53
Q

osteomalacia vs osteoporosis

A
54
Q

what is the stimulus for the release of VD?

A
55
Q

osteomalacia?

A

defective bone mineralization due to lack of VD (which is needed to absorb Ca from the gut)

The osteoid is produced, BUT, Ca+ salts r not adequetly deposited>> bones r soft and weak

osteoid is the ground matrix which consists of ground substance

56
Q
A
57
Q

rickets?

A

is osteomalacia but in children.

bc the epipheseal plate cannot caldify, long bone become abnormally long and widen

58
Q

risk factors for Osteoporosis?

A
59
Q

consequences of Osteoporosis

A
60
Q

The control of plasma Ca2+ differs from the regulation of Na+ and K+ in 2 important ways

A
61
Q

alkaline phosphatase?

if raised, what is it an indication of?

A
62
Q

what r the 2 main mechanisms by which malignancy can cause hypercalcaemia:

A
63
Q

structure of bone

A
64
Q
A
65
Q
A
66
Q

Name these findings

what r they sign of?

A

HYPOCALCEMIA

1) Chvostek’s sign

tap on facial nerve at angle of Jaw> mouth will twitch

is a clinical sign of existing nerve hyperexcitability (tetany) seen in hypocalcemia. When the facial nerve is tapped at the angle of the jaw (i.e. masseter muscle), the facial muscles on the same side of the face will contract momentarily (typically a twitch of the nose or lips) because of hypocalcemia

2) Carpopedal spasm

67
Q

Causes of Hypocalcemia

A
68
Q

Symtoms of HYpocalcemia

A
69
Q

symptoms of severe hypercalcemia occur whe clacium serum levels r higher than______

how do u treat it?

A

3.0mmol/L

High calcium levels the kidney tries to dump then in the urine> the polyurea can lead to dehydration> must REHYDRATE THEM

70
Q

Sensory symptoms of Hypocalcemia

A
71
Q

why can hypocalcemia kill?

A

Hypocalcemia can kill due to laryngeal muscle tetany, so needs treating quickly

Metabolism-Alaa (23 decks)

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