BONES Skeletal Physiology

DIFFERENT TYPE OF BONES

Long:

-Have a greater length than width

-Usually somewhat curved for strength purposes

-Examples: Femur, tibia, fibular, radius and ulna.

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SHORT BONES

Roughly cubed- shaped

Approximately equal width and length

Examples: Wrists and ankle bones (carpals &

tarsals)

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FLAT BONES

Made up of a layer of spongy bone between two

thin layers of compact bone.

Shape is flattened,

not rounded.

Examples:

Ribs & Skull

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IRREGULAR BONES

-Classified by not fitting into the categories of

the other types of bones

-Includes irregular shapes such as spine

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LONG BONE STRUCTURE

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-Articular cartilage: reduces friction and

absorbs shock at freely movable joints

-Spongy bone

-Compact Bone

-Medullary cavity: central cavity of bone

shafts where red bone marrow and/or

yellow bone marrow is stored

-Endosternum: membrane that lies

cavity of the bone

-Periosternum: tough fibrous membrane

that surrounds the outside of bones

wherever they are not covered by

articular cartilage

COMPACT VS. SPONGY

Compact bone: made up of concentric rings of matrix that surround central canals which contain blood vessels.

Embedded in this bone tissue are small cave-like spaces called lacunae, which are connected to each other through small tunnels called canalicula.

Spongy bone: Looks like an irregular latticework (or sponge) with lots of spaces throughout.

These spaces are filled with red bone marrow which is the site of hematopoiesis or formation of blood cells.

These are our two types of osseous tissue and both provide their own structural advantages that resist bending and breakage

Hyaline Cartilage: - Semitransparent, has a bluish opalescent cast, glassy appearance

- Most common type of cartilage

- Covers the articular surfaces of bone

- Forms costal cartilages that connect anterior ends of the ribs with the sternum

-Forms cartilage rings in the trachea, bronchi of the lungs and tip of the nose.

Elastic Cartilage: - Forms the shape of the external ear

- Forms the epiglottis that covers the respiratory tract when swallowing

- Forms auditory tubes that connect middle ear and nasal cavity

- Yellowish color

- Greater opacity than hyaline cartilage

Fibrocartilage: - Characterized by small quantities of matrix and abundant fibrous elements

- Associated with dense connective tissue

-In the symphysis pubis, intervertebral disks and near the points of some large

tendons to bones

Cartilage: - Interstitial growth: cartilage grows from within, tissue mass divides

then secretes additional matrix, most common in childhood and

early adolescence because of the softness of the cartilage

- Appositional growth: external growth, chondrocytes in

perichondrium divide and secrete additional matrix which is then

deposited on the surface of cartilage, once initiated continues

beyond adolescence and continues for the rest of one’s life.

Bone: - Infants are born with more cartilage than bone and slowly the

cartilage models are transformed in to actual bone.

- Calcification of organic bone matrix is needed for bones to develop.

This occurs when complex calcium salts are deposited in.

Functions of the Bone 1. Mechanical support of soft tissues

2. Levers for muscle action

3. Protection of the central nervous system

4. Release of calcium and other ions for the maintenance of a constant ionic

environment in the extra cellular fluid.

5. Housing and support of hemipoiesis The structure and amount of bone, both at the macroscopic and microscopic level,

are determined by the genetic blueprint and by regulatory factors that help carry out

bone functions

To accomplish its functions the bone undergoes continuous destruction,

called resorption, carried out by osteoclasts and formation by osteoblasts.

Intramembranous ossification is the transformation of the mesenchyme,

cells of an embryo into bone. Endochondral ossification is the gradual

replacement of cartilage by bone during development. This process is

responsible for formation of most of the skeleton of vertebrate animals. Most

bones arise from a combination of intramembranous and endochondral

ossification.

Questions: 1. Cancer treatment may generate a need for a bone marrow transplant.

Osteoporosis is a condition characterized by an excessive loss of calcium in

bone. These 2 conditions are disruptions or failures of 2 bone functions.

Identify these 2 functions and explain what their normal function should be.

-The two functions should be Mineral storage and blood cell manufacture. Calcium

and phosphorus, the two most abundant minerals in the body, are stored in bones

as well as red blood cells are manufactured by bone marrow.

2. Explain why a bone fracture along the epiphyseal plate may have serious

implications among children and young adults.

-Crooked or misshapen bones could result from an untreated epiphyseal fracture

in children and young adults because the epiphyseal plate is an area that

produces new bone tissue and determines the final length and shape of bones in

adulthood.

3. During the aging process, adults face the issue of a changing skeletal

framework. Describe these changes and explain how these skeletal framework

changes affect the health of older adults.

- As men and women age, the structure of bone changes and this results in loss

of bone tissue. Low bone mass means bones are weaker and as time goes on, it

becomes more risky to take a fall. If I child falls on his knees he can get right back

up however if an elderly man did, he possibly could shatter his patella.