CH 6 Bones and Tissues

What is cartilage?

supporting connective tissue

What are the characteristics of cartilage?

• no blood vessels

• flexible tissue

• consist of water (60-80%)

• formed by chondrocytes (from embryonic state)

What are the types of cartilage?

• hyaline

• elastic

• fibrocartilage

Where can you find hyaline cartilage?

ends of bones in joints, connecting the ribs to the sternum, and supporting the respiratory tract.

every part of articulation

Where can you find elastic cartilage?

cartilage in external ear, epiglottis, eustachian tube, larynx

Where can you find fibrocartilage?

in intervertebral discs, pubic symphysis, and menisci of the knee.

What three things make up bones?

• specialized cells

• protein fibers

• extracellular matrix (vascularized )

What are the functions of bone?

1. support

2. mineral storage

3. blood cell production

4. protection

5. movement

6. production of fat storage

Bone function: support

framework for attachment of tissues and organs

Bone function: mineral storage

calcium and phosphate

Bone function: protection

organ such as heart and brain are protected

Bone function: movement

bones are levers, bones change magnitude and direction of force generated by muscles

Bone function: production of fat storage

production of osteocalcin influences fat storage (reduction), insulin production (increasesand sensitivity, and glucose metabolism.

Low osteocalcin in bone →

reduced insulin sensitivity and increased fat mass.

High osteocalcin in bone →

increased insulin sensitivity and reduced fat mass.

Four specialized cell types of bones

1. osteocyte

2. osteoblast

3. osteoprogenitor

4. osteoclast

Origin of cells (bone)

mesenchym

Parts of bone: cells

Osteocyte

mature bone cell that maintain the bone matrix

main; round with extensions → pass chemical info

Osteoblast

immature bone cell that secretes osteoid, the organic bone matrix

Osteoprogenitor

stem cell that divides to produce osteoblasts

Osteoclast

multinucleate cell that secretes acids and enzymes to dissolve bone matrix

Osteogenesis

The process of bone formation, which involves the differentiation of osteoblasts and production of the bone matrix.

uses the bone cell type called osteoblasts to create new bone tissue.

Osteolysis

The process of bone resorption where osteoclasts break down bone tissue, releasing minerals and collagen into the bloodstream.

uses the bone cell type called osteoclasts to dissolve the bone matrix.

liberate mineral storage

What is the importance of fibers in bone?

tolerate stretching, twisting, and bending (spiral orientation)

provide an organic framework for the formation of mineral crystals

What is responsible for a majority of the bone weight?

collagen fibers represent 1/3 of bone weight

What is the matrix in bone?

calcium phosphate: hydroxyapatite

What combination of the matrix is found in the lamellae?

hydroxyapatite crystals + protein fibers = protein-crystal

Where are protein crystals?

Protein crystals are found in the bone's lamellae, where they contribute to its structural integrity.

Two types of bone

compact and spongy

Compact bone?

external wall

Spongy bone location

internal layer

Function of spongy bone

protects the medullary cavity (bone marrow)

Two types of bone marrow in spongy bone

yellow and red

What is yellow marrow?

dominated by adipocytes

Where can you find yellow bone marrow?

found in shaft and end of long bones

What is red bone marrow?

tissue dominated by blood cells

Where can you find red marrow?

found in flat bones and long bones

What is the functional unit of compact bone?

osteon or Haversian system

What lamellae make up compact bone?

• concentric

• circumferential

• interstitial

Concentric lamellae

of each osteon are parallel to the long axis of the bone (bull’s eye target)

Circumferential lamella

located at the internal and external surface of the bone

Interstitial lamellae

fill the space between osteons

Structure of spongy, trabecular, or cancellous bone

parallel, thick, branching plates or bars

Trabeculae

arrangement of spongy bone is into parallel thick branching plates or bars

Importance of trabeculae in spongy bone

reduce the weight of skeleton = easier movement of bones

How do trabeculae help with force?

force (ie body weight) is directed downward to large bones to distribute it

hip to the metaphysis

across the knee joint to the rest of the leg

Parts of a long bone (ie humerus and femur)

epiphysis, metaphysis, diaphysis (shaft), articular surface

Most superior portion/ tips of long bone

epiphysis

Metaphysis

the region between the epiphysis and diaphysis of a long bone, where growth occurs and the bone widens.

Diaphysis (shaft)

the long, tubular main section of a long bone that provides strength and support.

What is periosteum made from?

connective tissue → dense irregular

Function of periosteum

isolate and protect the bone

provides a route and place to attachment for insertion points to tendons and ligaments

Importance of periosteum

important in bone growth and repair

rich in blood vessels and nerve

Diagram: periosteum

periosteum: fibrous layer (bone repair), osteogenic layer (produce new cells)

Endosteum locations

• lines the medullary cavity (marrow)

• lines inner surfaces of central canals and perforating canals

• covers the trabecular of spongy bone

Importance and diagram of endosteum

bone growth and repair

How is blood supplied to bones?

blood vessels and artery

What is the nutrient artery and nutrient vein?

enter through nutrient foramen

to supply blood to the bone's medullary cavity and trabecular bone.

Types of vessels for bone blood supply

• epiphyseal

• metaphyseal

• periosteal

Epiphyseal vessels

supply medullary cavities of the epiphyses (through foramina)

Metaphyseal vessels

supply to diaphyseal surface

bone is replacing cartilage

ossification of bones

Periosteal vessels

supply superficial osteons (compact bones)

Diagram of blood supply to bone

Nerve supply in the bones

periosteum

sensory nerves

Periosteum role in nerve supply (bone)

contains a network of lymphatic vessels and sensory nerves

What do sensory nerves in bone innervate?

1. endosteum

2. medullary cavity

3. epiphyses

Why are bone injuries painful?

Bone injuries are painful due to the stimulation of sensory nerves in the periosteum and surrounding tissues, which transmit pain signals to the brain.

lots of nerves!

What are the seven bone shapes for classification?

1. sutural (Wormian)

2. Pneumatized

3. short

4. irregular

5. flat

6. long

7. sesamoid

Some Pirates Sneak Some Interesting Flat Logs

Sutural bones

small, flat, oddly shaped bones found between the flat bones of the skull along the sutures

they develop from separate centers of ossification

Pneumatized bones

bones that are hollow or contain numerous air pockets, such as the ethmoid bone

Short bones

boxlike in appearance

external surfaces are covered by compact bone, but the interior contains spongy bone

carpal bones and tarsal bones

Irregular bones

have complex shapes with short, flat, notched, or ridged surfaces

internal structure is equally varied

vertebrae that form the spinal column and several bones in the skull

flat bones

thin, roughly parallel surfaces of compact bone

spongy bone sandwich

strong but relatively light

form the roof of the skull, sternum, ribs, and scapulae

protect underlying soft tissues and have an extensive SA for the attachment of skeletal muscles

aka parietal bones

thick layers of compact bone aka internal and external tables

diploe: spongy bone between tables

Long bones

long and slender

diaphysis, 2 metaphyses, 2 epiphyses, medullary cavity

upper and lower limbs

humerus, radius, ulna, femur, tibia, fibula

Sesamoid bone

small, round, flat

develop inside tendons and are most often encountered near joints at the knee, hands, and feet

kneecaps

Bone markings or surface features function: depression and openings

passageway of blood vessels and nerves

Bone markings or surface features TYPES: depression and openings

1. foramen

2. groove

3. fissure

4. notch

5. fossa

6. meatus

7. sinus

foramen

round or oval opening through a bone

groove

furrow

fissure

narrow, slitlike opening

notch

indentation at the edge of a structure

fossa

shallow basinlike depression in a bone, often serving as an articular surface

meatus

canal-like passageway

sinus

cavity within a bone, filled with air and lined with mucous membrane

Bone markings or surface features TYPES: surfaces that form joints

1. head

2. facet

3. condyle

head

bony expansion carried on a narrow neck

facet

smooth, nearly flat articular surface

condyle

rounded articular projection, often articulates with a corresponding fossa

Bone markings or surface features TYPES: projections that are sites of muscle or ligament attachment

1. tuberosity

2. crest

3. trochanter

4. line

5. tubercle

6. epicondyle

7. spine

tuberosity

large rounded projection; may be roughened

crest

narrow ridge of bone; usually prominent

trochanter

very large, blunt, irregularly shaped process (only examples are on the femur)

line

narrow ridge of bones; less prominent than a crest

tubercle

small rounded projection or process

epicondyle

raised area on or above a condyle

spine

sharp, slender, often pointed projection

Bone markings or surface features: process and ramus

Process

any projection or bump

Ramus

an extension of a bone that forms an angle with the rest of the structure

L shape