Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chapter 6: Bones & Skeletal Tissues (The objective of this chapter is…
Chapter 6: Bones & Skeletal Tissues
The objective of this chapter is to gain understanding of the anatomy and physiology of bones and its individual structures
Cartilage
The human skeleton is initially made up of cartilages and fibrous membranes
By the time the body reaches maturity most of the cartilage in the body is replaced by bone
The cartilage that remains in the body is found where flexible skeletal tissue is needed
Cartilage is made mostly of water making it resilient to pressure and giving it the ability to spring back to its original shape
Cartilage is avascular meaning it has no nerves or blood vessels
Cartilage is surrounded by dense irregular connective tissue called the perichondrium
There are three types of cartilage
3 more items...
The perichondrium acts as reinforcement to resist outward expansion when the cartilage is compressed
1 more item...
Cartilage has a flexible matrix that can accomodate mitosis
1 more item...
Cartilage can become hardened and calcified under certain conditions. THIS IS NOT BONE
Bones
Function of bones
There are seven important functions that bones perform
Anchorage
Skeletal muscle attaches to bones by tendons
They are attached at certain points along bones so when the muscles contract, movement is caused
Mineral Storage
Bone acts as a storage of minerals such as calcium and phosphate
This stored minerals can be released whenever there is a need for them somewhere else in the body
Protection
EX. The skull protects the brain
EX. The vertebrae surround the spinal cord
Blood Cell formation
Blood cell formation also known as hematopoiesis occurs in the red bone marrow
Support
Bones provide framework that supports the body
EX. The rib cage supports the thoracic wall
EX. The bones of the lower limbs support the trunk of the body while standing
Fat Storage
Fat is stored in yellow bone marrow and used for energy
Hormone production
Bones produce osteocalcin
Osteocalcin is a hormone that helps regulate insulin secretion, glucose homeostasis, and energy expenditure
Classification of bones
Bones are classified by location and shape
Short bones
Short bones are roughly cube shaped EX. carpals and tarsals
A special type of short bone is a sesamoid bone
A sesamoid bone forms in a tendon EX. patella
Flat bones
Flat bones are thin, flattened and usually a bit curved
EX. Sternum, scapulae, rubs, and most cranial bones
Long bones
Long bones are longer than they are wide
The general structure of a long bone is a long shaft with two bulging ends
EX. Femur, phalanges, ulna, radius, etc
Irregular bones
Irregular bones have complicated shapes that don't fit they other classifications
EX. Hip bones and vertebrae
Bone anatomy
Bones are complex organs made of different types of tissues
The anatomy of bones can be broken down into three levels
Microscopic anatomy
General cells of bone tissue
There are five major cells in bone tissue
Osteocytes
1 more item...
Bone lining cells
1 more item...
Osteoblasts
1 more item...
Osteoclasts
1 more item...
Osteoprogenitor cells
1 more item...
Compact bone
The microscopic structure of compact bone reveals tree like rings
The structural unit of compact bone is called the osteon
1 more item...
Chemical level
Bone consists of organic and inorganic components
Organic components
The organic components of bone include its cells and osteoid which is the organic part of the matrix
1 more item...
Inorganic components
The inorganic component of bone is made of hydroxyapatites
1 more item...
Gross Anatomy
Short,irregular and flat bones
These three types of bones have a thin layer of spongy bone called diploe
The diploe is sandwiched by compact bone on both sides
1 more item...
These types of bones do not have a defined shaft, expanded ends, and are not cylindrical
These types of bones contain bone marrow between trabeculae
Long bones
Long bones all have the general structure of a shaft with two bulging ends
The tubular shaft of the long bone is called the diaphysis
1 more item...
The bulging ends of the long bone are called epiphyses
1 more item...
Between the diaphysis and the epiphyses lies the epiphyseal line (in adults) or the epiphyseal plate (in children)
1 more item...
General structure
Every bone has an outer and an inner layer
The dense outer layer of bone is called compact bone
The inner layer is called spongy bone
1 more item...
Membranes
Bone has an inner and an outer membrane covering
2 more items...
Bone markings
Bones are covered in distinct markings that can give information about how the bone works with surrounding muscles or ligaments
1 more item...
Bone marrow
There are two types of bone marrow
Red marrow
1 more item...
Yellow marrow
1 more item...
There are three states in which bones can change
Bone remodeling
Bone remodeling replaces about 5-10% of the skeleton each year
The entire skeleton is replaced about every 10 years
Bone remodeling is necessary because if bone remains in place for a long period of time the calcium salts crystallize and the bone becomes brittle
Bone remodeling is a balance of bone resorption and bone deposition
Bone resorption
1 more item...
Bone deposition
1 more item...
Bone remodeling is a continuous process that occurs
Bone remodeling is regulated by two control loops each with a specific purpose
2 more items...
Bone repair
Bone repair occurs only after a break or a fracture of a bone
Fractures are classified by
Completeness
Whether or not the bone is broken through
Complete
1 more item...
Incomplete
1 more item...
Whether the bone ends penetrate the skin
Simple (closed)
The bone does not penetrate the skin
Compound (open)
The bone penetrates the skin
Position
Where the bone ends after fracture
Displaced
1 more item...
Nondisplaced
1 more item...
There are four stages in the process of bone repair
Fibrocartilaginous callus forms
New blood vessels soon grow into the clot
Fibroblasts and chondroblasts from nearby periosteum and endosteum enter the fracture site
1 more item...
Bony callus forms
Within the mass of repair tissue osteoblasts begin to form spongy bone
Osteoblasts lay trabeculae inside of and around the fibrocartilaginous callus
1 more item...
A hematoma forms
The breaking of the bone causes blood vessels in the periosteum and the surrounding tissues to tear
The hemorrhaged blood clots and forms a hematoma
1 more item...
Bone remodeling occurs
This last stage begins during the formation of the bony callus
The excess material on the diaphysis and within the medullary cavity is removed
1 more item...
Common types of fractures are
Fissured
Bone has an incomplete longitudinal break
Spiral
Bone breaks as a result of excessive twisting forces
Greenstick
Bone breaks incompletely (one side breaks the other side bends)
Compression
The bone is crushed
Comminuted
Bone fragments into three or more pieces
Depressed
The broken portion is pressed inward
Epiphyseal
Eiphysis separates from the diaphysis along the epiphyseal plate
Bone development/growth
Development
During the embryonic stage of development the skeleton consists only of fibrous connective tissue membranes and hyaline cartilage
Around the 8th week bone tissue begins to develop and eventually will replace most fibrous or cartilage structures
There are two ways in which bones develop
Intramembranous ossification
1 more item...
Endochondral ossification
1 more item...
Growth
Bones can either grow lengthwise or in thickness
Lengthwise is referred to longitudinal bone growth
There are four zones in which longitudinal bone growth occur that somewhat mimic endochondral ossification
This type of growth is contingent on whether or not the epiphyseal plate has solidified into the epiphyseal line
4 more items...
Growth in thickness is referred to as appositional growth
The process of appositional bone growth involves osteoclasts and osteoblasts working in tandem
This allows bone to widen without becoming heavier
2 more items...
The rate of bone growth is dictated by hormone regulation
Thyroid hormones
Sex hormones
Growth hormone
KEY