bones 206 bones are said to be in the human skeleton. although the human skeleton is initially made...

BONES

206 Bones are said to be in the Human Skeleton.

Although the human skeleton is initially made up of cartilages and fibrous membranes this is soon replaced by bone.

BonesBasic Structure, Types, and

Locations When discussing the skeleton is it

essential to review over the types of cartilages found in the body.– Hyaline Cartilages– Elastic Cartilages– Fibrocartilages

Cartilage

Hyaline Cartilage- Provides support with flexibility and resilience. Makes up the following in the human skeleton– 1. articular cartilage- covers the ends of most

bones– 2. costal cartilage- connect ribs to sternum– 3. respiratory cartilage – found in make up

larynx – 4. nasal cartilage- which support the external

nose.

Elastic Cartilage- Very much like hyaline cartilage but ALSO contains more stretch elastic fibers and better able to stand repeated bending.– Makes up only 2 skeletal locations– 1. external ear-– 2. epiglottis- flap that covers the opening

to the larynx each time we swallow.

Cartilage

Fibrocartilages Cartilage- are highly compressible and have great tensile strength. It is in between hyaline and elastic cartilages– Found in sites that are subjected to both

heavy pressure and stretch. – 1. Menisci- padlike cartilages of the knee– 2. Disk between the vertebrae.

Cartilage

Cartilage

Always remember bone and cartilage are always distinct different tissues.

Bone has a hard matrix while cartilage has a flexible matrix that can accommodate mitosis.

Division of the Skeleton

Axial Skeleton- consists of the bony and cartilaginous parts that support and protect the organs of the head, neck and trunk.

Appendicular Skeleton- consists of the bones of the upper and lower limbs and bones that anchor the limbs to the axial skeleton.

Bone StructureBone Structure

Bones differ in size and shape but have similar structure, development, and functions.

Bone ClassificationBone Classification

Long Bones

Long longitudinal axes, and expanded end.

Ex: Forearm and thigh bones.

Short Bones

Cube like, with lengths and widths roughly equal .

Bones in the wrists and ankles.

Bone ClassificationBone Classification

Flat Bones

Plate like structure with broad surfaces

Ex: Ribs, scapulae, and some bones of the skull.

Bone ClassificationBone Classification

Irregular Bones

Variety of shapes and are usually connected to several other bones.

Ex: Vertebra, and some facial bones.

Bone ClassificationBone Classification

Bone ClassificationBone Classification

Bones shape, support, and protect body structures.

They also act as levers. House tissue that

produces bone/blood cells

Stores various inorganic salts.

Bone FunctionBone Function

Bone FunctionBone Function

Support- all the softer tissues of the body; they literally hang from the skeletal framework.

Protection- hard, bony “boxes” protect the delicate structures within them. Example: skull to brain

Movement- Muscles are anchored firmly to bones.

Bone FunctionBone Function

Mineral and Growth Factor Storage-

Bone is a reservoir for minerals like calcium and phosphate. It also stores important growth factors.

Blood Cell Formation- Most blood formation or hematopoiesis occurs in the marrow cavities of certain bones.

Bone StructureBone Structure

Because bones contain tissue they are considered an organ

They contain not only bone (osseous) tissue but nervous tissue, connective tissue, muscle tissue, and epithelial tissue.

Bone Marking

Throughout the next month as you work with this bones you will need to recognize these markings during lab

Bones are rarely smooth..they display projections, depressions, and openings that serve as sites of muscle, ligament, and tendon attachment as joint surfaces or conduits for blood vessels and nerves.

Bone Marking

Projections (bulges) that grow outward from the bone surface includes– Heads, trochanters,

spines, and others. – These are just a few

a complete list is on pg 179

Bone Marking

Bone depressions and opening include– Fossae, sinuses,

foramina, and grooves

– These are just a few a complete list is on pg 179

Bone Texture

When discussing bone texture the outward appearance has a smooth solid look to the naked eye and is referred to as Compact Bone

The internal layer is referred to as Spongy Bone and looks like a honeycomb.

We will discuss this in more detail later.

Diaphysis- Shaft of the bone, located between epiphysis. A hollow tube made of hard compact bone, hence a rigid and strong structure light enough in weight to permit easy movement.

It surrounds a central medullary cavity…”Marrow cavity”

In adults the medullary cavity contains fat (yellow marrow) and is called yellow bone marrow cavity.

Structure of a Long Bone

Structure of a Long Bone

Epiphysis- The outer ends (joints) of a long bone. The exterior of epiphysis is compact bone

while the interior of epiphysis is spongy bone. Outer portion of the epiphysis is coated with a

layer of hyaline cartilage called Articular Cartilage. Functions like a small rubber cushion .

Red bone marrow fills in small spaces in the spongy bone composing the epiphyses.

Structure of a Long Bone

Epiphysis Between the epiphysis and diaphysis of

an adult long bone is an epiphyseal line and remnant of the epiphyseal plate.

The epiphyseal plate is a disc of hyaline cartilage that grows during childhood to lengthen the bone.

Structure of a Long Bone

Another structure in all long bones are membranes– Peristeum- a strong fibrous membrane

covering a long bone except at joint surfaces, where it is covered by articular cartilage.

– A thin membrane containing bone-forming cells called Endosteum lines the internal bone surfaces.

Structure of a Long Bone

Structure of a Long Bone

2 Types of Bone

Compact Bone- Wall of the diaphysis is mainly composed of this. Hard and dense; continues matrix with no gaps.

Spongy Bone- Found on the ends of the epiphysis…consists of many branching bony plates. Contains spaces that may be filled with marrow. The needle-like threads of spongy bone that surround a network of spaces are called trabeculae.

Microscopic- Anatomy of Bone

In Compact Bone the matrix is organized into numerous structural units called osteons or Haversian systems. Each circular and tube like osteon is composed of calcified matrix.

The rings are called a concentric lamella.

Parts of the Long Bond

Draw and label the long bone on pg. 180 in book.

http://www.mhhe.com/biosci/ap/holeessentials/student/olc/matching0160.html

http://kidshealth.org/kid/body/bones_SW.html

Bone Development

Ossification and Osteogenesis are synonyms meaning the process of bone formation.

In embryos this process leads to the formation of the bony skeleton

And continues on until early adulthood as the body continues to grow in size.

Bone Development

The first 8 weeks of development the human embryo is completely fibrous membranes and cartilage

Bones continue to grow and develop into adulthood.

Bones form by replacing existing connective tissue in one of two ways

Intramembranous Bones and Endochondral Bones

Bone Development

INTRAMEMBRANOUS BONES

When a bone develops from a fibrous membrane it is called intramembranous ossification and the bone is called a membrane bone.

Intramembranous ossification results in the formation of Flat Bones (Mostly of the skull and clavical).

During development membrane like layers of connective tissues appear at the area of future bones.

Layers supplied with blood vessels and tissue arranged around the vessels

Cells enlarge and change into bone-forming tissue called OSTEOBLAST.

ENDOCHONDRAL BONES

Ex: Most all bones They develop as hyaline cartilage that is later

replaced by bone tissue. This is more complex than intramembranous

ossification because the hyaline cartilage must be broken down as ossification proceeds

Primary ossification centers appears in the diaphysis, whereas secondary ossification centers appear in the epiphyses

An epiphyseal plate remains between the primary and secondary ossification centers. Development proceeds from masses

Osteo….The different types bone cells.

Osteoblasts - make new bone and help repair damage;

Osteocytes- mature bone cells.carry nutrients and waste products to and from blood vessels in the bone;

Osteoclasts- break down,reabsorb bone and help to sculpt and shape it. Osteoclasts are very active in kids and teens, working on bone as it is remodeled during growth. They also play an important role in the repair of fractures.

Bone Growth- Epiphyseal Plate

An epiphyseal plate consists of layers of cells: resting cells, young cells, older enlarging cells and dying cells.

The epiphyseal plates are responsible for lengthening.

Long bones continue to lengthen until the epiphyseal plates are ossified.

Bone Growth- Epiphyseal Plate

Growth in thickness is due to intramembranous ossification beneath the periosteum.

The action of osteoclasts forms the medullary cavity.

HOMEOSTASIS OF BONE TISSUE

Osteoclast and osteoblast continually remodel bone.

The total mass of bone remains nearly constant throughout life. While it may appear to be lifeless it is VERY active

Adult skeleton normally recycles 5-7% of our bone mass a week…spongy bone replaced every 3-4 years, compact bone every 10.

Factor Affecting Bone Development

Sunlight, hormonal secretions, and exercise all affect bone development

Deficiencies of vitamin A,C, or D result in abnormal development.

Physical stress Exercise thickens

and strengthens bone tissue

Lack of activity can cause waste and thin tissue.

BONE- Blood Cell Formation

Hemopoiesis- the process of blood formation.

Begins in the yolk, which lies outside the embryo. Later in development, blood cells are manufactured in the liver, spleen, and still later they form in the bone marrow.

BONE- Blood Cell Formation

Marrow- soft tissue within the medullary cavity of long bones, in spongy bone, and in canals of compact bone tissue.

MARROW

RED MARROW- Functions in the

formation of red blood cells, white b.c’s and blood platelets

Occupies most cavities of infant bones, later replaced by yellow marrow.

Yellow Marrow• Stores fat• Inactive in blood cell

production.• By adolescence, most

of our marrow is yellow

• Red blood cells only live about 120 days, they are replaced or recycled.

Blood cell production in ADULTS routinely occurs in the heads of the _femur_ and humerous_.

If you were to obtaining red marrow samples from the body. Some of the best places to go would be the Sternum and hip bones. Hematopoiesis are very active here

Inorganic Salt Storage

The intercellular matrix of bone tissue contains collagen and inorganic mineral salts.

The crystals that are formed are a type of CALCIUM phosphate.

The need for Calcium

Our body requires calcium for a number of vital metabolic processes;

Blood clot formation.Nerve impulse conduction.Muscles cell contractions.

The need for Calcium

When the blood is low in calcium, parathyroid hormone stimulates osteoclasts to break down bone tissue, releasing calcium salts from the intercellular matrix into the blood.

Osteomalacia

Osteomalacia- includes a number of disorders in which the bones are inadequately mineralized. Two examples of this included..

Rickets – is just osteomalcia that is seen in young children

Rickets

Rickets is a softening of bones in children due to deficiency or impaired metabolism of vitamin D, phosphorus, or calcium

Potentially leading to fractures and deformity. Rickets is among the most frequent childhood diseases in many

developing countries. The predominant cause is a Vitamin D deficiency, but lack of

adequate calcium in the diet may also lead to rickets (cases of severe diarrhea and vomiting may be the cause of the deficiency).

Although it can occur in adults, the majority of cases occur in children suffering from severe malnutrition, usually resulting from famine or starvation during the early stages of childhood.

Rickets

Osteoporosis

Osteoporosis- refers to a disease in which bone resorption outpaces bone deposits.

Bones become fragile and therefore easily fractured. a condition that results from loss of bone minerals.

Osteoporosis

BONES

206 Bones are said to be in the Human Skeleton.

This numbers varies between people.

Structural bones may develop in the area where the flat bones of the skull fuse.

Bone Repair

Despite remarkable strength, bones are susceptible to fractures or break!

Resulting from twists or smashing of bones. Excessive intake of vitamin A and elevated

blood levels of the protein homocysteine may increase the risk as well as thin and weaken bones that accompany age.

Bone Repair

Non-displaced fractures- the bone will retain their normal position

Displaced Fractures- the bones are out of their normal position

Bone Repair

Complete Fracture- the bone is broken in two; completely through

Incomplete Fracture -the bone is not.

Bone Repair

Linear Break- the break parallels the long axis

Transverse Break- the break is perpendicular to the bone’s long axis.

Bone Repair

Compound Fracture- the bone ends penetrate the skin

Simple Fracture- the bone does NOT penetrate the skin.

Axial Skeleton

Skull Hyoid bone Vertebral column (which includes

sacrum and coccyx) Thoracic cage (which includes ribs

and sternum)

Appendicular Skeleton

Pectoral girdle (scapula, clavicle) Upper limbs (humerus, radius, ulna,

carpals, metacarpals, phalanges) Pelvic girdle (as coxae, pelvis) Lower limbs (femur, tibia, fibula,

patella, tarsals, metatarsals, phalanges)