L6: The Parathyroid Gland

Question 1

Chief cells produce _

Answer 1

PTH

Question 2

Oxyphil cells

Answer 2

Absent in infants and children
Appear at puberty
Role unknown

Question 3

Where is calcitonin produced in thyroid glands

Answer 3

Parafollicular cells (C cells)

Question 4

Low Ca stimulates ..

Answer 4

PTH

Question 5

High Ca stimulates

Answer 5

calcitonin

Question 6

What are the physiological effects of PTH?

Answer 6

Bone, Kidney -> intestine

Question 7

We do not want Ca and ___ to be reabsorbed at the same time

Answer 7

PO4

Question 8

What are the 3 effect of PTH?

Answer 8

Bone: bone reabsorption and Ca efflux
Kindey: Increase in 1,25 Dihydroxycholecalciferol, increase in Calcium and decrease in PO4 reabsoription
Intestine: Increased Ca and PO4 absrobed at the same time

Question 9

How is PTH activated?

Answer 9

A decrease in calcium detected by the CaSR

Question 10

What is the half life of PTH?

Answer 10

4mins (short)

Question 11

PTH causes an increase in Ca reabsorption and PO4 _____

Answer 11

excretion

Question 12

Activates calcitriol to increased Ca and PO4 absorption in the

Answer 12

GI

Question 13

What are the target organs of PTH?

Answer 13

Bones and kidneys

Question 14

PTH _____ Ca from bones

Answer 14

releases

Question 15

Where is calcitonin released from?

Answer 15

Parafollicular cells (c cells) in thyroif

Question 16

What works antagonitsically to PTH?

Answer 16

Calcitonin

Question 17

Calcitonin _____ with an increase in Ca

Answer 17

increase

Question 18

What is a stronger regulator of Ca? PTH or calcitonin

Answer 18

PTH

Question 19

How does calcitonin protect against hypercalcemis

Answer 19

lowering serum Ca

Question 20

What activates calcitriol?

Answer 20

PTH

Question 21

THe active form, vitamin D3 requires

Answer 21

PTH

Question 22

Composition of bone __% inorganic _% organic

Answer 22

65% inorganic - hydroxyapatite
35% organic - osteoid

Question 23

Inorganic bone is for

Answer 23

compressional strength

Question 24

organic bone is for

Answer 24

tensile strength

Question 25

What are the 3 types of bone cells?

Answer 25

Osteoblasts (bone formation) Osteoclasts (resorption) Osteocytes (trapped osteoblasts mature bone cells)

Question 26

2 types of bone tissue

Answer 26

cortical - 80% of bone mass (outside layer) Trabecular - 20% (cont being replaced)

Question 27

4 disorders associated with the parathyroid gland?

Answer 27

Rickets - osteomalacia Osteoporosis Hyperparathyroidism Hypoparathyroidism

Question 28

Rickets - osteomalacia

Answer 28

Calcium or phosphate deficiency Normally related to a decrease in vitamin D Mainly seen in children If untreated, PTH secretion will increase bone osteoclast activity and lead to weak bones

Question 29

Treatment for rickets

Answer 29

Vitamin D plus calcium and phospate replacement Basis for vitamin D supplements in milk and bread (fortified)

Question 30

Osteoporosis

Answer 30

Most common bone disease in adults Decreased bone matrix due to decreased osteoblast activity Malnutrition, post-menopausal changes in estrogen, reduced GH and lack of bone matrix, Cushing's syndrome (too much cortisol decreases osteonblast activity)

Question 31

Treatment for osteoporosis

Answer 31

Biphosphonates Bind to bone surface and slow osteoclast resorption of bone Allows osteoblasts to work more effectively

Question 32

Hyperparathyroidism

Answer 32

Innapp secretion of PTH Incease in bone resorbtion Increase calcium/phosphate levels Kidney stones adenoma on parathyroid glands

Question 33

Treatment for hyperparathyroidism

Answer 33

removal of adenoma

Question 34

Hypoparathyroidism

Answer 34

Too little PTH Hypocalcemia Muscle twitches and spasms that can lead to tetany Damage to parathyroid gland (thyroidsectomy, autoimmune)

Question 35

Treatment for hypopara

Answer 35

Calcitriol and Ca supplements