Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PHSL 233 > L22 > Flashcards

L22 Flashcards

1
Q

what is rickets

A

Rickets – due to a deficiency or impaired
metabolism of vitamin D, calcium or phosphorus.

The predominant cause is vitamin D deficiency.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what activates metabilisum of vitamin D

A

The kidney activates metabilisum of vitamin D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

describe the difference between healthy bones and bones of those with rickets

A

Normal individual has a thick bone and quite ossified (little openings)

In rickets the bones are think an the bones are porous, they get bone softening and troubles with their teeth, they also have muscle weakness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is osteoporosis

A

Osteoporosis is when the bone mass and density is reduced. They have very weak bones and have a high incidence of hip replacement as they fall over and break the bones which then need to be replaced. They also have lots of knee replacement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what % of new zealanders are lactose intolerant

A

10%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Ca homeostasis is a balance between what organs

A

kidney, intestine and bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

daily intake of Ca = daily Ca excreted

what % of Ca is excreted in feces and urine

A

feces = 80% (800mg ish)

urine 20% (200mg ish)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the concentration of Ca in the body

bone/teeth, ICF and ECF

A

bone/teeth = 99% of the bosies Ca

  • ICF = generally < 0.1 µM (1%)
  • ECF = 2-3 mM (0.1%)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what Ca concentrations define hyper and hypocalcemia

A

–ECF > 3 mM = hypercalcemia (High Ca2+ blood)

–ECF < 2 mM = hypocalcemia (Low Ca2+ blood)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why is it important to maintain appropriate ICF and ECF concentrations of Ca2+?

theres 8

A
  • proper bone formation
  • neurotransmission (release of vesical)
  • mitosis, cell division and growth
  • muscle contraction
  • blood clotting
  • growth
  • enzymatic reactions
  • 2nd messenger function
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what does hypocalcemia (low ECF Ca) cause

A

• increase excitability of:
– nerve cells
– muscle cells

• pins and needles
• airway obstruction (increase in mucus)
• epileptic seizures
• cardiac arrhythmias
• hypocalcemia tetany
– muscle spasms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what does hypercalcemia (high ECF Ca) cause

A

• decrease excitability of:
– nerve cells
– muscle cells

  • disorientation
  • lethargy (lack of energy)
  • cardiac arrhythmias
  • death
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which of the following statements is TRUE?

A. The bulk of Ca 2+ in the body is located within the ICF.

B. Low ECF Ca2+ causes decreased excitability of nerve cells.

C. The ECF Ca2+ concentration is between 2-3 mM.

D. Osteoporosis causes and increase in bone mass

A

A. bulk in bone/teeth

B. causes increased excitability. decreased outside = increased inside as things are relative (I think)

D. decrease in bone mas

C is correct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how is Ca found in the plasma

3 ways

A

• 50% of the Ca2+ is ionized

• 40% of the Ca2+ is bound to protein
(normally albumin), thus not filtered

• 10% of the Ca2+ is complexed with anions (HCO3, citrate, phosphate, SO4=)

So, only 60% of the plasma Ca2+ can be filtered!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what % of Ca in the plasma can be filtered

A

60%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what % of Ca in the plasma can be filtered

A

60%

as the 40% bound to albumin is not filtered (proteins can’t get through the filtration barrier)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the equation for dailey filtered load of an ion

A

eg Ca

GFR x [Ca2+]plasma = Daily filtered load

180 L/day x 2.5 mmol/L = 450 mmoles/day
(filtered)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what % of Ca does the PT reabsorb

A

50-60% of the filtered load of Ca

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how does the PT reabsorb Ca

A

Ca transport is 100% via the paracellular pathway

occurs via solvent drag

20
Q

what % of Ca does the thick ascending limb reabsorb

A

15% of daily filtered load of Ca

21
Q

how does Ca get reabsorbed in the thick ascending limb

A

paracellular pathway

22
Q

what controls the permeability of the tight junctions of the thick ascending limb

A
  • Claudin-16 plays a role in maintaining the permeability of the tight junctions that favours transport and Ca2+, Mg2+ and Na +
23
Q

where is the Ca sensor receptor located

A

on the basolateral membrane of the thick ascending limb

24
Q

what is the role of the CaSR

A

it monitors the ECF concentration of Ca

If you are in hypERcalcenia it will be detected by the Ca sensor receptor which will alter the function (downregulate) NKCC and the K channel (ROMK)

Under hyPOclacemic conditions it will not down regulate

25
Q

what % of the dailey filtered load of Ca does the distal convoluted tubule reabsorb

A

10-15%

26
Q

what are the primary transporters of Ca in the distal convoluted tubule

A

TRPV5 and TRPV6

these are Ca channels in the apical membrane which move Ca down its concentration gradient

27
Q

once Ca enters the distal convoluted tubule cell how does it get from the apical to the basolateral membrane

A

calbindin

this is a Ca binding protein which helps shuttle Ca across the cell

28
Q

what are the Ca membrane proteins in the basolateral membrane (to get Ca out of the cell)

A

Ca ATPase (PMCa1b)

Na/Ca exchanger (NCX1)

29
Q

how many Na and Ca are transported via the Na/Ca exchanger (NCX1)

A

3Na into the cell and 1Ca out of the cell

30
Q

in the distal convoluted tubule Ca does NOT move through the paracellular pathway. why is this

A

Claudin 8 (CLND8) is a tight junctional protein which prevents the movement of Ca2+

this is located in DCT

31
Q

Which of the following statements is FALSE?

A. 50% of the Ca2+ in plasma is ionized.

B. 60% of the blood Ca2+ can be filtered at the glomerulus.

C. The proximal tubule reabsorbs 50-60% of the filtered Ca2+.

D. Ca2+-sensing receptors monitor the intracellular Ca2+
concentration.

A

D is false because it should say extracellular concentration of Ca

32
Q

what hormones are involved in Ca homeostasis

A
  • Parathyroid hormone

* Calcitriol

33
Q

when and where (which cells) is parathyroid hormone (PTH) secreted from in Ca homeostasis

A

• Parathyroid hormone is secreted from the parathyroid gland

– the calcium sensing receptor on the membrane of the chief cells monitors ECF Ca2+ levels and when it detects hypocalcemia PTH is released

34
Q

PTH causes 3 things to happen to try and increase extracellular Ca concentrations. what are these

A

PTH stimulates bone resorption (break down) which releases Ca2+ into the plasma

PTH also stimulates reabsorption of Ca2+ by the TAL and DT

PTH increases the release of calcitriol which results in increased Ca2+ absorption by the intestine

35
Q

what is PTH effect on the bones

A

PTH stimulates bone resorption (break down) which releases Ca2+ into the plasma

therefore increase in Pi and Ca release

36
Q

what is PTH effect on the nephron

A

PTH also stimulates reabsorption of Ca2+ by the TAL and DT

37
Q

how does PTH effect the intestine

A

PTH increases the release of calcitriol which results in increased Ca2+ absorption by the intestine

38
Q

PTH has 2 effectors what are these

A

bone and the kidneys

39
Q

what is PTH overall effect on the kidneys

3 things

A

increases Pi excretion

decreases Ca excretion

increases calcitriol production (which goes on to cause the intestines to increase Ca and Pi absorption)

40
Q

what is calcitriol

A

metabolite of vitamin D3

41
Q

what secretes calcitriol

A
  • activated in the kidney – proximal tubule (PT)

• Calcitriol is released by the influence of PTH due to low calcium

42
Q

what are the effects of calcitriol

theres 4

A
  • stimulates resorption (breakdown) of bone and releases Ca2+ into the plasma
  • stimulates reabsorption of Ca2+ by the DT
  • stimulates Ca2+ absorption by the intestine
  • negative feedback on the parathyroid gland to regulate the release of PTH
43
Q

what is calcitriols effect on the bone

A

• stimulates resorption (breakdown) of bone and releases Ca2+ into the plasma

44
Q

what is calcitriols effect on the nephron

A

• stimulates reabsorption of Ca2+ by the DT

45
Q

what is calcitriols effect on the intestine

A

• stimulates Ca2+ absorption by the intestine

46
Q

what role does calcitriol play in negative feedback on PTH

A

• negative feedback on the parathyroid gland to regulate the release of PTH

47
Q

Which of the following statements is FALSE?

A. The kidneys, bone and intestine all play roles in Ca2+ homeostasis.

B. The parathyroid hormone is released by high plasma Ca2+.

C. Calcitriol is activated vitamin D3.

D. Parathyroid hormone stimulates resorption of bone

A

B is false as PTH is released in low conc of Ca

PHSL 233 (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions