Lecture 12- Skeletal System Pt 1 Flashcards
How many bones are in the axial skeleton?
80
How many bones are in the appendicular skeleton?
126
What regions does the axial skeleton contain?
Skull, vertebral column, and thoracic cage
Which skeleton division contains the upper and lower limb bones and the bones of the pectoral and pelvic girdles?
Appendicular
What are the 6 shape classifications of bones?
Flat
Long
Sesamoid
Irregular
Short
Sultural
Is trabecular bone or compact bone more porous?
Trabecular bone
50-90% porous
Is the adult skeleton made up of more trabecular bone or compact bone?
Compact bone
80% of adult skeleton is compact bones
What is the main function of flat bone and how does it achieve this?
Protection
Compact bone, spongey bone, compact bone sandwich=protection from inner layer of bone
What are the ends of long bones called?
Epiphysis
______ is the tubular shaft of the long bone which runs between the proximal and distal epiphysis
Diaphysis
Where is red bone marrow located in the long bones?
Epiphysis
Where is yellow bone marrow found in the long bones?
Diaphysis
Where do RBC and WBC form?
Epiphysis where the red bone marrow is found
Where is adipose tissue located?
Diaphysis where the yellow bone marrow is found
_____ connects each epiphysis to the diaphysis
Metaphysis
Metaphysis contains epiphyseal plates in children. What are they called in adults?
Epiphyseal line
No longer cartilage, is now bone
The microscopic structural unit of compact bone is called an _____
Osteon
Each osteon contains concentric rings of calcified matrix called ______
Lamellae
Where are osteocytes located?
What are the spaces called?
Lacunae
What connects with lacunae to permit nutrient transport, waster removal, and communication between osteocytes?
Canaliculi
What is the periosteum?
The outer sheath that contains blood vessels, nerves, and lymphatic vessels
Does the periosteum or endosteum contain osteoblasts, fibroblasts, and skeletal stem cells?
Periosteum
Perry the platypus blasts Dr. Doofenshmirtz
Tendons and ligaments also attach to bones at the ________
Periosteum
What is the endosteum?
The membrane that lines the medullary cavity
Where are osteoclasts found?
The endosteum
True or false: Trabeculae in the spongy bones have a random arrangement
False!
Forms along lines of stress to provide strength to the bone
Where are lacunae and osteocytes found in SPONGY bone?
Lattice-like network of matrix spikes called trabeculae
Why is spongy bone important in regards to energy use?
Makes bones lighter so muscles can move easier with less energy consumption
What are bone stem cells called? What can they differentiate into?
Osteogenic cells
Osteoblasts
What is the role of osteoblasts?
Forms the bone matrix
What is the role of osteocytes?
Maintains bone tissue
How do osteoblasts become osteocytes?
Osteoblasts secrete collagen matrix/calcium salts. As the secreted matrix around the osteoblast calcifies, the osteoblast becomes trapped within it and becomes an osteocyte
_____ originate from monocytes and macrophages which are two types of white blood cells
Osteoclasts
______ break down old bone while _____ are continually building new bone
Osteoclasts- break
Osteoblasts- build
OsteoBlasts=Build
What bone shape is intramembranous ossification involved with?
Flat bone
What bone shape is endochondral ossification involved with?
Long bone
What do mesenchymal cells in the embryonic skeleton differentiate into?
Capillaries and osteogenic cells which become osteoblasts
Early osteoblasts appear in a cluster called an _____ _____
Ossification center
Osteoblasts secrete ____ which is unclassified but eventually calcifies trapping the osteoblasts within it
Osteoid
Why is bone formation/intramembranous ossification a repeating process?
Osteogenic cells surround CT differentiate into osteoblasts which eventually calcify and become osteocytes
What forms when blood capillaries interrupt bone formation from osteoid?
Trabecular matrix (spongy bone)
After the trabecular matrix forms, osteoblasts on the surface become the ________
Periosteum
What does the periosteum create superficial to the trabecular (spongy) bone
Protective layer of compact bone
Overall what are the steps in intramembranous ossification?
- Mesenchymal cells differentiate in capillaries and osteogenic cells which form osteoblasts
- Osteoblasts clusters are called an ossification center where osteoid are secreted
- Osteoid calcifies and entraps osteoblasts within it
- Osteoblasts become osteocytes
- Osteogenic cells surrounding CT differentiate into new osteoblasts
- Blood capillaries interrupt bone formation and create a trabecular matrix
- Osteoblasts on surface of spongy bone become the periosteum
- Periosteum creates protective layer of compact bone sandwich
- Trabecular bone marrow crowd nearby blood vessels which condense into red marrow
Trabecular bone crowds nearby blood vessels, eventually condensing into ____ ________
Red marrow
In endochondral ossification what do some of the mesenchymal cells differentiate into in long bone?
Chondrocytes (cartilage cells)
What is the membrane that covers the cartilage called?
Perichondrium
As more matrix is produced the chondrocytes _____ and ______
Grows and calcifies
Due to calcification of the matrix, nutrients can no longer reach the chondrocytes, resulting in ____ of surrounding _____
Death of surrounding cartilage
When blood vessels invade the spaces, what type of cells are carried with them which will eventually become osteoblasts?
Osteogenic cells
The enlarging spaces from blood vessel invasion combine to eventually become the ______ ______
Medullary cavity
What does the cartilaginous perichondrium transform into?
Periosteum (bone)
How do bones increase in length but not width?
Chondrocytes and cartilage continue to grow at the epiphysis ends which increases bone length
Bone replaces cartilage in the diaphysis middle which stops continuous growth
True or false: Secondary ossification is the same steps as endochondral ossification
True
Matrix mineralizes, chondrocytes die, blood vessels invade, osteogenic cells form osteoblasts
By the time the fetal skeleton is fully formed, where does cartilage remain?
Between the diaphysis and epiphysis as articular cartilage
Overall what are the steps of endochondral ossification?
- Mesenchymal cells become chondrocytes
- Chondrocytes form matrix in hyaline cartilage
- Calcification of matrix leads to cell death
- Blood vessels invade cavity and carry osteogenic cells
- Bone develops
Overall what are the steps of intermembranous ossification?
- Mesenchymal cells become osteoblasts
- Osteoblasts gather in ossification center
- Osteoblasts secrete osteoid and calcium
- Calcified matrix traps osteoblasts which turn into osteocytes
- The presence of blood capillaries causes bone to form as trabeculae (spongy) bone in the middle
- On the surface bone tissue forms compact bone
