Week 9 (exam 3) Flashcards
What are the 2 structures of the bone?
1) spongy or cancellous bone
2) compact bone
What is spongy or cancellous bone made with?
Made with trabeculae (sg trabeculum)
What is trabeculae?
Little struts that criss cross each other
If you take a strut and look under a microscope you will see lamella, lacunae, canaliculi in red bone marrow
What is compact bone?
Thick and solid
Has a central canal or Haversian canal
Has many osteons or haversian systems
Waste goes in cell to central canal and nutrients from canal go outward through the cell
Why do bones bleed?
Because of the central canal or Haversian canal
How are bones formed?
1) dermal membrane or membrane bone or intramembranous bone
2) endochondrial (cartilage replacement bone)
What is dermal bones or membrane bone or intramembranous bone?
CT membrane in fetus that is laid down
Osteoblasts in membrane starts to make bony matrix
Center of ossification or ossification system
What is the dermis?
Lower layer of skin where bone initially develops
What is the center of ossification or ossification center?
Where process of bone formation begins and where it spreads out
What does ossification mean?
Bone formation
What is endochondrial?
Begins as hyaline cartilage
Includes bones in limbs
Becomes bone over time
What is an epiphyseal plate?
The cartilage that is left in bone when you’re a teenager
What happens when epiphyseal plates go through closure?
The bone cannot grow anymore
Person is in their late teens
What are epiphyseal lines?
Where the epiphyseal plates were
Happens in late teens
What is the articular cartilage?
Only cartilage left in bone
Thin little layer at the joint
Late teens
How is the medullary cavity or marrow cavity formed?
When the process of creating bone through endochondrial is done or almost done osteoclasts kick in and remove matrix inside bone
What is a medullary cavity or marrow cavity and what is found in it?
Hollow space in bone where yellow marrow or white marrow is found (basically fat)
What is remodeling in bone?
The constant dance between osteoclasts (breaking down matrix) and osteoblasts (building up matrix)
Where can you take and store Ca if needed?
Skeleton
What are the 2 major regulators of Ca?
1) parathyroid gland (4 of them in the back of thyroid glands)
2) thyroid gland
What is secreted from the parathyroid gland and what does it do?
Parathyroid gland hormone
PTH increases osteoclasts activity
- breaks skeleton down and blood Ca levels rise
What is secreted from the thyroid gland and what does it do?
Calcitonin hormone
Inhibits activity of osteoclasts
-blood Ca levels drop
What kind of cells produce calcitonin?
Parafollicular cells or C cells
What happens to the osteoblasts when a person gets older?
Bone becomes brittle lack of collagen
Osteopenia
Osteoporosis
What is osteopenia?
Insufficient ossification (decrease in bone density and not strong enough)
What is osteoporosis?
Osteopenia to the extreme
Extreme danger of fracture and breaks
Pores appearance
What are Bisphosphonates?
Class of drugs to reduce osteoporosis
Slows down osteoclasts and balances out osteoclasts with how slow osteoblasts are going