Musculo I

Question 1

Osteoprogenitor cells

Answer 1

mesenchymal stem celsl that differentiate into osteoblasts

Question 2

osteoblasts

Answer 2

bone forming cells

secrete osteoid matrix (type I collagen)

differentiate into osteocytes when trapped by matrix

Question 3

osteoclasts

Answer 3

bone resorbing cells derived from monocyte/macrophage precursors

Question 4

compact bone

Answer 4

composed of osteons

• central canal (haversian): blood vesses and nerves
• concentric lamellae
• osteocytes: housed in lacunae and contain cytoplasmic projections in canaliculi

Question 5

bone marrow

Answer 5

red bone marrow: site of formation of all blood cells (hematopoiesis) in adult, rich in GF

yellow bone marrow: largely composed of adipose tissue

Question 6

Hyaline cartilage

Answer 6

lacunae house chondrocytes surrounded by an intracellular matrix of collagen fibers

no BV (heals slowly) or nerves

location: artic cartilage, costal cart, cart of respiratory tract, and epiphyseal plates

Question 7

Fibrocartilage

Answer 7

structure: more collagen fibers in that hyaline cart

resists compression, absorbs shock in some jts

location: IV discs, pubic symphysis, menisci of knee jts

Question 8

Hormone regulation of bone: role of PTH

Answer 8

role: PTH increase level of ionized (free) calcium in the blood
- inc calcium reabsorption from bone
- inc calcium reabsorption from kidney, decreases phosphate reabsorption
- indirectly inc calcium and phosphate from the intestine by activating vit D

Question 9

Hormone regulation of bone: production of PTH

Answer 9

produced by parathyroid glands attached to the thyroid gland

secreted in response to low blood calcium (hypocalcemia)-chronically elevated PTH leads to bone demineralization

Question 10

Hormonal regulation of bone: production of Vit D

Answer 10

vit D3 (cholecalciferol) is produced in the skin in response to UV light

Question 11

Hormone regulation of bone: actions of Vit D

Answer 11

actions: increases intestinal absorption of calcium and phosphate from the intestine (inc calc and phosphate availability for bone mineralization)

directly promotes bone reabsorption (activation of osteoclasts and inhibition of osteolasts)

inhibition of bone remodeling (mobilization of old bone and deposition of new bone)

vit D activation increased by PTH (PTH stimulates vit D3 in the kidney)

Question 12

Long bones structure: endosteum

Answer 12

endosteum- membrane lining spaces of the spongy bone, marrow cavities, and Haversian canals of compact bone

contains osteoprogenitor cells, osteoblasts, and osteoclasts for bone formation/remodeling

Question 13

Long bones structure: periosteum

Answer 13

covers bones except at articular ends

inner layer contains osteoprogenitor cells and osteoblasts for growth and repair