Chapter 6 Flashcards
The Skeletal system
-5 functions
- Support
- Storage of minerals
- Blood cell production
- Protection
- Movement
Classification of bones by shape
-6 shapes
- Long
- Short
- Flat
- Irregular
- Sesamoid
- Sutural
Long bone
- definition
- 6 examples
- Relatively long and
1. Arm
2. Forearm
3. Thigh
4. Leg
5. Fingers
6. Toes
Short bone
- definition
- 2 examples
- cube like; greater in width then length
1. wrist
2. ankle bones
Flat bone
- definition
- 3 examples
- thin and flat
1. sternum, skull bones, ribs
Irregular bone
- definition
- 3 examples
- complex shapes
1. vertebrae
2. sphenoid
3. os coxae
Sesamoid
- definition
- example
- “sesame seed” shape
- patella
Sutural
- definition
- location
- small, flat, and irregularly shaped
- located between flat bones of skull
Periosteum
- definition
- 3 functions
- fibrous and cellular layer
1. Protection
2. Growth and prepare
3. Provides route for blood vessel entry
Endosteum
-3 functions
- Lines marrow cavity
- connective tissue and cells
- Growth and repair
Nutrient artery
main blood supply to bone
Marrow cavity
- what is it also known as
- what does it contain
- “medullary”
- contains yellow marrow (fat)
Spongy bone
- what is it also known as
- definition
- “cancellous” or “trabecular”
- Porous and contains red bone marrow
Compact bone
- dense
- surrounds bone
- deep to periosteum
Epiphyseal line
starts as cartilage and ends as bone
Basic functional unit of mature contact bone
osteon
Osteon
- what type of system
- definition
- Haversian system
- arrangement of osteocytes in lacunae in concentric circles
Central Canal
- aka
- definition
- haversian canal
- contains blood vessels (artery and vein) and nerves
Osteocyte
- definition
- housed where
- function
- mature bone cell that maintains the bone matrix (most mature)
- in lacunae
- maintains protein and mineral content of bone
Canaliculi
- definition
- which way does it run
- small passageways that link lacunae to the central canal
- vertically
lamellae
matrix rings
Perforating canal
- aka
- which way does it run
- volkman’s canal
- runs horizontally
Spongy bone in haversian system
Forms struts and plates = trabeculae
Composition of bone
- cells
- matrix
- only makes up 2% of tissue and are far apart
- most abundant component (98%) and include organic and inorganic
Osteoblast
- definition
- 2 functions
- immature bone cell
1. secretes organic components of matrix
2. bone builders
Osteoprogenitor cell
-definition
Bone stem cells whose division produces osteoblasts (least mature)
Osteoclasts
- definition
- function
- multinucleate cell
- secretes enzymes to dissolve bone matrix (breaks down bone)
Inorganic bone matrix
- carbon?
- what is it made up of
- what does it form
- what does it provide
- no carbon
- calcium and phosphorus salts
- forms hydroapatites ~65%
- Provides strength to matrix
Organic bone matrix
- what elements does it include
- what is it made up of
- function
- carbon and hydrogen
- collagen fibers (~35%)
- Tough yet flexible = provides tolerance to distortion
when does ossification occur?
about 6 weeks after fertilization
2 types of ossification
- intramembranous ossification
2. Endochondral ossification
Intramembraneous ossification
- definition
- 2 examples
- key point
- 5 steps
- within a membrane (forms in dermis)
- most of skull, clavicle
- bone are built from a fibrous connective tissue membrane
1. ossification center formed in fibrous membrane
2. Osteocytes deposit minerals
3. Blood vessels
4. Formation of a plate of spongy bone
5. Periosteum surrounds the entire bone
Ossification center formed in fibrous membrane
-3 things happen
- mesenchymal cells cluster and develop into osteoblasts
- osteoblasts begin secreting organic component of bone matrix
- this group of osteoblasts forms an ossification center
Osteocytes deposit mineral salts
-3 things happen
- osteoblasts develop into osteocytes
- osteocytes deposit calcium salts in matrix (calcification)
- Developing bone growth outward in small struts called spicules
Blood vessels recruitment
-3 things happen
- blood vessels grown between spicules
- rate of bone growth accelerates
- blood vessels become trapped within the bone
Formation of a plate of spongy bone
-2 things happen
- continued deposition of bone by osteoblasts
- blood vessels are found weaving through
Periosteum surrounds the entire bone
-2 things happen
- spongy bone is formed initially and is remodeled to produce compact bone
- periosteum develops around the bone
Endochondral ossification
- definition
- key point
- 5 steps
- Cartilage model enlarges
- Blood vessels grow around edges
- Invasion of vessels and formation of marrow cavity. Primary ossification center formed in diaphysis
- Secondary ossification center formed in epiphyses. Marrow cavity is created as osteoclasts become active
- Remaining cartilage (articular cartilage and epipyseal plate)
The growth of bones
-2 ways
- Appositional growth
2. Epiphyseal growth
Appositional growth
-definition
- grow in width
- cells of the periosteum (osteoblasts add layers of bone)
Epiphyseal
- definition
- what does it include
- direction of cartilage growth
- grow in length
- epipyseal plate
- upwards
Age at which bone growth in length ends? why?
18-25 years old
-epiphyseal cartilage has closed and formed the epiphyseal line because bone production became greater than cartilage growth
Factors affecting bone growth
-3 things
- Nutrition
- Hormones
- Exercise
Nutrition
- calcium and phosphorus
- vitamin D = Necessary for absorption of Ca++ in the gut
- vitamins A, C, K, B12 = Stimulate osteoblasts and protein synthesis
Hormones
- definition
- 5 types
- chemical messengers
1. Growth hormones
2. Thyroid hormone
3. Sex hormone
4. Calcitonin
5. Parathyroid hormone
growth hormone
promotes growth of bones by stimulating osteoblasts
thyroid hormone
Promotes bone growth by stimulating osteoblasts
Sex hormone
Testosterone + estrogen stimulate bone growth
Calcitonin
works to decrease blood Ca++ levels by stimulating osteoblasts
-regulates Ca++ in blood
Parathyroid hormone
works to increase blood Ca++ levels by stimulating osteoclasts
-regulates Ca++ in blood
