bones and cartilage

How much of body weight do bones make up?

18%

How much of body weight comes from muscles?

36-40%

What percentage of our bones is compact bone/ivory bone/cortical bone?

80%

What percentage of our bones are spongy/cancellated/trabecular bone?

20%

Cartilage does NOT

Have blood (avascular) or nerve (non-innervated) supply

Tendons are made up of

Collagen

What kind of tissue are ligaments and tendons made up of?

Dense regular connective tissue

Function of tendons

Connect muscles to the bones by insertion, can be tight or loose

What are some features of collagen

Strong, flexible, not elastic

Muscle tendons can not

Change in length

Ligaments are made up of

Collagenous tissue

Function of ligaments

Connect bone to bone, soft tissue to bone

Ex: uterus is connected to its bone through ligaments

Functions of bones

Support, protect, movement, mineral storage, hemopoiesis

What are the weight-bearing bones?

Pelvis, femur, tibia, tarsals

What organs does the pelvic bone protect?

Uterus, urinary bladder, prostate, sigmoid colon

What organs does the rib cage protect?

Heart and lungs

What minerals do bones store?

Ca2+ and phosphate

Erythropoiesis occurs when?

There is hypoxia (low oxygen supply)

Erythropoiesis process:

Hypoxia ➡stimulate kidneys ➡ kidneys secrete erythropoietin (hemopoietin) ➡ go to bone marrow and make red blood cells

Where does erythropoiesis take place?

Bone marrow

What percent of cartilage is water and what does it mean?

80%, means cartilage is compressible

Weeping lubrication

Cartilage is compressed and fluid goes to the surface and spreads

What cells make cartilage?

Chondroblasts

What do Chondroblasts do?

Deposit new cartilage, secrete the cartilage matrix

What is the cartilage matrix made out of?

Glucosaminoglycans (GAGs) - chondroitin sulfate, hyaluronic acid

What is the backbone of cartilage matrix?

Hyaluronic acid

Chondrocytes are

Trapped in matrix, living cells, and maintain the cartilage

Layer that surrounds cartilage is

Perichondrium

Chondrocytes are surrounded by

Lacuna

What type of fibers do chondroblasts make?

Collagen fibers, elastic fibers

Elastic fibers are made up of

Elastin

Elastic cartilage features

Has a lot of Chondrocytes and elastic fibers

Where can we find elastic cartilage?

External ear (ear pinna), epiglottis, and larynx

fibrocartilage features

Tough, highly collagenous, can resist pressure

Where can we find fibrocartilage?

Intervertebral discs and pubic symphysis

Pubic symphysis expands at

Parturition

Vertebrae is oriented with

Spinous process, facing backwards and downwards

When intervertebral discs are herniated

The spinal nerve is compressed and the person has pain in the lumbar region

Where is hyaline cartilage found?

Joints, costal cartilages (in rib cage), trachea and bronchial rings, thyroid and arytenoid cartilages (in larynx), nasal cartilage, ends of long bones (epiphyseal plate)

What is the most abundant cartilage in the body?

Hyaline cartilage

Where does bone elongation take place?

Epiphyseal plate

What happens to epiphyseal plate when growth stops?

It turns into epiphyseal line

What type of cartilage is this?

Fibrocartilage

What type of cartilage is this?

Elastic cartilage

What type of cartilage is this?

Hyaline cartilage

What are the types of growth of cartilage?

Appositional growth and interstitial growth

What is appositional growth?

Cartilage grows from outside ➡ in

What is interstitial growth?

Expansion is from inside ➡out

Compact or ivory bone features

Hard, weight bearing, strong

Spongy or cancellated bone features

Made up of small pieces called trabeculae, easy to remodel (absorption and formation) because the pieces are small

The smallest bone in the body is

In the ear called stapes it is also the innermost in the ear

What are the bones in the middle ear?

Malleus, incus, and stapes

Examples of small bones

Pisiform, stapes

Long bones features and examples

Longer than broad

Ex: Femur, humerus, tibia, phalanges, metacarpals, metatarsals

The largest bone in the body is

In the pelvis, ileum

Flat bones examples

Ribs, sternum, skull bones, scapula

Short bones examples

Carpals and tarsals

Irregular bones examples

Vertebrae

Wormian bones examples

Small sutural bones usually in lamboidal suture

Sesamoid bone features and examples

Muscle tendon becomes ossified (hard and bony)

Ex: quadriceps tendon forms patella, carpi ulnaris forms pisiform

Diploe bones features and example

Contains spongy bone in the middle of compact bone, compact bone gives strength and spongy makes it weigh lighter

Ex: Skull bones

What is the Inca bone

A Wormian bone found in Inca population in lamboidal suture

The two ends of bones are covered with

Joint/articular cartilage

The middle part of the bone is

Compact bone

The bone is covered by the membrane

Periosteum

Spongy bone surrounds the

Epiphyseal plate

Epiphyseal plate is made of

hyaline cartilage

The ends of bones are called

Epiphysis

The middle part of the bone is called

Diaphysis

In between epiphysis and diaphysis is

Metaphysis

Inside the bone it is called

Medullary cavity

Where is the bone marrow

In the medullary cavity

The inside of the bone is lined by

Endosteum

Layers of periosteum

Outer layer: fibrous layer

Inner layer: osteogenic layer

Where are osteoblast and osteoclast found?

Osteogenic layer of periosteum and in endosteum

Sharpey’s fibers

Connect the periosteum with the surface of the bone

Muscle tendon is inserted in

Periosteum

Osteoprogenitor cells

Stem cells that give rise to blood origin hemopoietic cells and mesodermal origin mesenchymal cells

Mesenchymal cells give rise to

Osteoblasts

Function of osteoblasts

Bone formation (mineralization) or bone deposition which makes alkaline conditions

Make bone matrix and trap cells that are now called osteocytes

Osteocytes are

Trapped in matrix, living, communicate with each other via canaliculi, maintain bone health

Canaliculi are

Cytoplasmic connections between osteocytes

Hemopoietic cells give rise to

Osteoclasts

Function of osteoclasts

Large, multinucleated cells with ruffled border

Bone resorption (demineralization) or bone remodeling, secrete acid

Clastogenesis or osteoclastogenesis means

Bone resorption

Osteocytes are formed by

Trapped osteoblasts

Osteoclasts secrete

Hyaluronic acid that dissolves bone

Haversian canal

Vertical canal in compact bone that houses blood vessels and nerves

Lamella

One ring layer of the osteocyte, canaliculi and bone matrix

Osteon is

A collection of lamella

Interstitial lamella

Incomplete lamella in between the osteons

Circumferential lamella

Not formed in rings, on outer surface of bone

Perforating canals or volkmann’s canals

Transverse canals that carry blood vessels

The spongy bone does not have

Haversian system

Spongy bone is made of

Trabeculae

What is osteoid part of bone formation

Organic part where we have proteins

Proteins in osteoid

Osteocalcin, osteopontin, collagen type I (most common)

Collagen type I provides

Pliable-Tensile strength (bone can bend slightly without breaking)

When collagen gene is mutated

COL1A1 (gene) mutation causes osteogenesis imperfecta (brittle bone disease)

What is osteogenesis imperfecta

Inherited condition where there are frequent fractures in bones because they break easily