Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

HHD 2 > Calcium and Parathyroid > Flashcards

Calcium and Parathyroid Flashcards

1
Q

How many parathyroid glands are ususally present?

A

4
however this is variable

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

Where are parathyroid glands usually located?

A

posterior to the thyroid glands

can also be locate in the mediastinum?

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

Blood supply to the parathyroid glands mirror the thyroid glands. True or false

A

True

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

What pharyngeal pouch do the inferior parathyroid glands originate from?

A

pharyngeal pouch III

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

What pharyngeal pouch do the superior parathyroid glands originate from?

A

pharyngeal pouch IV

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

What are the main cell types in the parathyroid glands and their functions?

A
  • chief cells - produces PTH (parathyroid hormone)
  • Oxyphil cells- unknown function

Chief cells in stomach produce pepsinogen

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

What is the speculated function of the oxyphil cells?

A

may secrete excess PTH in cancer of the parathyroid gland

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

What is the main function of the parathyroid gland?

A

calcium homeostasis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Outline reasons why calcium homeostasis is important

A
  • coagulation- factors II, VII, IX, X are dependent on calcium as they are negatively charged
  • nerve depolarisation
  • skeletal/smooth/cardiac muscle contraction
  • enzyme co-factors
  • cardiac stability
  • bone and teeth
  • regulation of hormone secretion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why is calcium important for cardiac stability ?

A
  • myocyte action potential/cardiac repolarisation cycle
  • phase 2 involves a calcium influx which slows down the rate of repolarisation (mediation of repolarisation)
  • also allows contraction of the the myocytes to carry on occuring
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Calcium is the most abundant mineral in the body. True or false

A

True
body contains around 1kg of calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How is calcium homeostasis achieved?

A
  • bones
  • intestines
  • kidneys
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Bones store 99% of the bodies calcium. How are bones involved in calcium homeostasis?

A
  • bone remodelling under control of PTH/calcitonin
  • osteoclasts resorb bone (release calcium into blood)
  • osteoblasts synthesise bone

osteoblasts send signals to osteoclasts before bone resorption occurs

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

When is parathyroid hormone released?

A

released when plasma/serum calcium levels are too low

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

When is calcitonin released?

A

released when plasma/serum calcium levels are too high
released from parafollicular cells

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

How are the intestines involved in calcium homeostasis?

A

they are involved in the absorption of calcium ions from the diet

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

How are the kidneys involved in calcium homeostasis?

A

majority of filtered calcium is reabsorbed in the kidneys
kidneys also convert inactive vitamin D into active vitamin D (calcitrol)

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

What is the function of parathyroid hormone?

A
  • increase serum calcium levels
  • stimulate osteoclast activity (bone resorbtion)
  • increases calcium reabsorption at the kidneys
  • increases phosphate excretion at the kidneys (less reabsorption of phosphate)
  • promotes kidneys to convert inactive vitamin D into calcitrol
19
Q

What is the function of calcitonin?

A
  • decreases serum levels of calcium
  • inhibits osteoclast activity- reduced bone resorption
  • increased calcium secretion at kidneys (less reabsorption)
  • decreases phosphate excretion at kidneys- increased phosphate retention; more phosphate moved into bones and bone fluid
20
Q

What is the function of calcitrol?

A
  • increased serum calcium levels
  • increased intestinal absorption of calcium
  • stimulates bone resorption (calcium mobilisation in bone)
  • increases calcium reabsorption at kidneys

similar action to PTH except PTH does not affect intestine

21
Q

What is the active form of vitamin D?

A

calcitrol
1,25 dihydroxyvitamin D

22
Q

How is the active form of vitamin D produced?

A
  • 7-dehydrocholesterol on the skin converted into cholecalciferol (vitamin D3)
  • Vitamin D3 (fish, meat), vitamin D2 (supplements) are obtained via dietary intake
  • vitamin D3 (cholecalciferol)/D2 are then 25 hydroxylated in the liver to produce 25-hydroxycalciferol
  • additional hydroxylation then takes place in the kidney to produce 1,25 hydroxycholecalciferol
23
Q

Vitamin D deficiency causes ________ in children

A

rickets
soft bone which spreads under pressure
pelvic, femural, tibial abnormalities

24
Q

What is the main function of vitamin D (aside from its role in calcium homeostasis)?

A

augment immune function

25
What are the symptoms of a vitamin D deficiency?
* excessive sweating * high blood pressure * tiredness and fatigue * digestive problems * mood swings * impaire immunity * psoriasis * overweight/obese * pain
26
What patients are at risk of vitamin D deficiency?
* infants and children aged under 4 * pregnant and breastfeeding women, particularly teenages and young women * people over 65 * people who have low or no exposure to the sun e.g. those who cover the skin for cultural reasons, who are housebound or confined indoors for long periods * people with darker skin, for example people of african, afro-carribean or south asian family origin
27
What is hypercalcaemia?
this is when serum calcium levels >2.6mmol/L
28
What are the causes of hypercalcaemia?
primary hyperparathyroidism- overproduction of PTH (adenoma, adenocarcinoma, hyperplasia) cancer >90% of cases
29
What is the classic presentation of hypercalcaemia?
Stones Bones Groans Psychiatric moans * renal stones (calcium oxalate); submandibular stones, lower prevalence in parotid * bone pain due to osteoporosis * abdominal pain, constipation and myalgia- pancreatitis, stomach ulcers * poor sleep, fatigue, depression, psychosis Polydipsia and polyuria also observed in hypercalcaemia in a similar way to glycosuria; calcium and glucose drag water out when not reabsorbed; leads to dehydration of cells hence polydipsia and resulting polyuria
30
What is the cause of primary hyperparathyroidism?
* overproduction of PTH by parathyroid * male >female * >80% of cases due to a single adenoma * elevated calcium with normal or elevated PTH
31
What is the cause of secondary hyperparathyroidism?
* excessive PTH production in response to chronically low Ca2+ ions; usually as a result of chronic renal failure - kidney failing to reabsorb calcium ions * decreased calcium levels with elevated PTH
32
What is the cause of tertiary hyperparathyroidism?
* parathyroid gland is chronically overstimulated, continues to produce excessive PTH despite normalisation of calcium * elevated calcium and elevated PTH *[resolution of kidney problems by parathyroid gland now programmed to overproduce PTH]
33
What investigations can be carried out for a diagnosis of hyperparathyroidism ?
* serum calcium, PTH and vitamin D * DEXA scan- bone density scan for osteoporosis * CT neck for surgical plannin- adenomas/lumps
34
How can primary hyperparathyroidism be managed?
* parathyroidectomy (adenoma) * monitor calcium levels annually * avoid medication that increases calcium levels (thiazide diuretics, lithium) * +/- vitamin D supplementation * +/- bisphosphonates
35
What is hypocalcaemia ?
serum calcium levels of <2.1mmol/L
36
What are the causes of hypocalcaemia?
most commonly hypoparathyroidism (autoimmne or iatrogenic) * vitamin D deficiency * alcoholism * eating disorders * CRF- chronic renal failure- failure to reabsorb * osteoporosis treatment * vomiting
37
What are the clinical signs of hypocalcaemia?
[CATS go numb] * convulsions * arrhythmias (prolonged QT interval on ECG) * Tetany, chvosteks sign, trousseaus sign * parasthesia in hands, feet and mouth (go numb)
38
What is Chvostek sign?
facial nerve spasm/twicth tap cheek; a twitch of facial muscle is observed
39
Tetany Vs tetanus
Tetanus is an infection Tetany- hypocalcaemic hyper-reactive nerves
40
What investigations are required for hypoparathyroidism?
* ECG * vitamin D * thyroid function * renal ultrasound
41
80% of hypoparathyroidism have a ___________ cause.
post-surgical
42
What is the management of hypoparathyroidism?
* severe: IV calcium with ECG monitoring * mild/moderate: oral Ca2+, PTH, thiazide diuretic
43
What are the dental considerations for hyperparathyroidism?
* osteoporosis * in children- tooth development defect and alteration in dental eruption * in adults- drifting of teeth, complaint of jaw pain, sensitive teeth when chewing and soft tissue calcifications * malocclusion due to drifting teeth, spacing of teeth may be the first signs of the disease * prone to developing cystic lesions around the mandible * brown tumours- filled with giant osteoclastic cells driven to increase calcium levels; granulomatous tissue * no lamina dura lining the socket; due to mobilisation of calcium from bone
44
What are the dental considerations for hypoparathyroidism
* enamel hypoplasia-not enough crown * delayed eruption * poorly calcified dentin * pulp calcifications * malformed roots * parasthesia in mouth [CATs go NUMB] * Facial muscle abnormalities- hyperactive nerves- due to hypocalcaemia

HHD 2 (37 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions