Human Anatomy & Physiology 5-6

What are the functions of the skeletal system?

Support
Storage of minerals and lipid

Blood cell production

Protection

Leverage

What is the function of support?

Provides structural support for the body

What is the function of storage of minerals and lipids?

Minerals contribute to osmotic concentration of body fluid, and enzymatic reaction

What is the function of Blood Cell production?

RBCs, WBCs and other blood are produced in the Red Blood Bone Marrow

What is the function of protection?

Ribs protect the heart and lungs, skull protects the brain, Vertebrae shields the spinal cord

What is the function of leverage?

Many bones function as levers that can change the direction of force generated by skeletal muscles

How many bones does the adult skeleton contains?

206

What are the 6 categories of bones?

Sutural

Flat
Irregular

Long

Short

Sesamoid

What are sutural bones?

Small and fill the gaps between bones of the skull

What are flat bones?

Thin parallel surfaces and protects underlying soft tissue

Roof of skull, sternum, ribs, and scapulae

What are irregular bones?

Complex shape with short, flat ridge, surfaces

What are short bones?

Carpal bones

Shape is boxlike and approximately equal dimensions

What are sesamoid bones?

Small, round and flat

The develop inside tendons and are most often encountered near joints at the knee

What are long bones?

Long and slender, consisting of shaft with two ends

Humerus in the arm

Femur in the leg

What are bone markings?

Surfaces of bone that have characteristic bone marking and surface features

What are the bone markings of the face?

Process

Ramus

Sinus

Foramen

Fissure

What is the process?

Projection or bump

What is the ramus?

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

What is the sinus?

Chamber within a bone, normally filled with air

What is the foramen?

Rounded passageway for blood vessels and/or nerves

What is the fissure?

Deep furrow, cleft, or slit

What is the epiphysis?

Forms the distal and proximal ends of a long bone

What is the metaphysis?

The areas where the epiphyses and diaphysis join

What is the diaphysis (shaft)?

Shaft or body of a long bone

What is the head of the long bones?

Expanded articular end

What is the neck of the long bones?

Narrow connection between epiphysis and diaphysis

What is the sulcus of long bones?

Narrow groove

What is the tubercle of long bones?

Small rounded projection

What is the tuberosity of long bones?

Small rough bump where a tendon attaches

What is the fossa of long bones?

Shallow depression

What is the trochlea of long bones?

Smooth, grooved bone

What is the condyle of long bones?

Smooth, rounded articular process

What is the trochanter of long bones?

Large rounded projection

What is the facet of long bones?

Small, flat articular surface

What does spongy bone contain?

Red Bone Marrow

What does medullary cavity contain?

Yellow Bone Marrow

What is the bone matrix?

Calcium phosphate CA3(PO4)2 makes up 2/3 weight of the bone

Ca3(PO4)2 + Ca(OH)2 → CA10(PO4)6(OH)2

What are bone cells?

Osteocytes

Osteoblasts
Osteogenic cells

Osteoclasts

What are osteogenic cells?

Bone stem cells

What are osteoblasts?

Derived from osteogenic cell and from bones

What are osteocyte (mature bone cells)?

Derived from osteoblasts, and prevents unwanted breakdown of bone

What are osteoclasts?

Come from the hematopoietic stem cell linage and break down bone

What is the role of osteogenic cells?

Stem cell whose division produce osteoblasts

What is the role of osteoblasts?

Produce new bone matrix (ossification or osteogenesis)

Secrete organic components of the bone matrix

Before Ca are deposited, organic matrix is called Osteoid

What are osteoids?

The developing or repairing of bone

What is the role of osteocytes?

Mature bones (making up most of the cell population)

Occupies space of matrix, which is called lacuna

Maintain protein and mineral content of matrix and take part in repair in damaged bone

What is the role of osteoclasts?

Absorb and remove bone matrix by secreting the digesting enzymes and acids that dissolve the matrix

Large cells have 50 or more nuclei

Derived from the same stem cells that produce monocytes and macrophages

What are canaliculi?

Narrow passageways that contain cytoplasmic extensions of osteocytes

What is the Osteon (Haversian system)?

Basic function unit of mature compact bone

Osteon contains blood vessels in central canal

What is the lacunae?

Pocket sandwiched between layers of matrix

What is the lamellae?

Layer of matrix, a thin plate

What is the perforating canal (Volkmann’s Canal)?

Channels the blood is distributed from surface of bone to deeper central cannals

What is the periosteum?

Layer of bone that is interwoven with tendons

Superficial layer of compact bone that covers all bones

What is the function of periosteum?

Isolates the bone surrounding tissues

Provides a route for the blood vessels and nerves

Takes part in bone growth and repair (Osteogenic cells)

What is the circumferential lamellae?

Layers of bone tissue immediately deep to the periosteum

What is the endosteum?

An incomplete cellular layer, lines the medullary cavity

What is the function of the endosteum?

Active during bone growth, repair, and remodeling

What is the function of trabeculae?

Tiny arches of bone tissue found in spongy bone

They form a meshwork of supporting bundles of fibers

What is the purpose of red bone marrow?

Hematopoiesis

What is the purpose of yellow bone marrow?

Fat storage

What is ossification / osteogenesis?

Process of forming new bone

What are the four situations of bone formation?

Formation of bone in an embryo (embryogenesis)

Growth of bones until adulthood (adolescent growth)

Remodeling of bone (continually)

Repair of fractures (injury)

What is endochondral ossification?

Cartilage is replaced by bone (CARTILAGE FORMED FIRST)

Forms both compact and spongy bone

What is intra-membranous ossification?

Products spongy bone directly (SPONGY BONE FORMED FIRST)

Bone may subsequently be remodeled to form compact bone

What do most bones originate from endochondral ossification?

Hyaline cartilage

What is step 1 of endochondral ossification?

Mesenchymal stem cells (associated with embryonic development) develop into condrocyte which form cartilage

What are the functions of chondrocytes?

They enlarge and the surrounding matrix beings to calcify

Enlarged chondrocytes die and disintegrate, leaving cavities within the cartilage

What is step 2 of endochondral ossification?

Blood vessels grow around the edges of the cartilage

Cell of perichondorium covert to periosteum

What is step 3 of endochondral ossification?

Early calcification leads to early development of spongy bone at the PRIMARY SITE of OSSIFICATION (Along the diaphysis)

First region of bone replacing cartilage

Blood vessels penetrate the cartilage and invade the central region

What is step 4 of endochondral ossification?

After ENTIRE diaphysis region is converted to bone (epiphysis region still cartilage)

Medullary cavity within the diaphysis is formed

Length and diameter are increased

What is step 5 of endochondral ossification?

Osteoblasts (a special class of bone tissue cells) migrate into the epiphysis

The two secondary ossification centers (the distal and proximal epiphyses ) become activated, and the cartilage in this region is converted to bone by calcification

What is step 6 of endochondral ossification?

The epiphysis becomes filled with spongy bone

Osteoblasts break the spongy bone along most of the diaphysis to form the medullary cavity

What is step 7 of endochondral ossification?

Articular cartilage is formed along the surface of the epiphyses

The epiphyseal plate is generated and will be responsible for LONGITUDINAL BONE GROWTH

What is another name of intra-membranous ossification?

Also called dermal ossification because it normally takes place in the deeper layers of dermis

The roof of the skull and clavicle are formed by this ossification

What is step 1 of intra-membranous ossification?

Mesenchymal cells (stem cells) cluster together, differentiate into osteoblasts and start to secrete organic components of the matrix

What is step 2 of intra-membranous ossificaiton?

Some osteoblasts are trapped inside bony pockets where they differentiate into osteocytes

The developing bone grows outward from the ossification center in small struts (spicules)

What is step 3 of intra-membranous ossification?

Blood vessels begin to branch

The rate of bone growth accelerates with oxygen and supply of nutrients

What is step 4 of intra-membranous ossification?

Continued deposition of bone by osteoblasts located closed to blood vessels results in a plate of spongy bone

What is step 5 of intra-membranous ossification?

Subsequent remodeling around blood vessels produces osteons, typical bone of compact bone

Osteoblasts on the bone surface, along with connective tissue around the bone, become the periosteum

What is the purpose of blood and nerve supply to the bone?

Blood supply is necessary for bone growth

What is the nutrient artery and vein?

The blood vessels that supply the diaphysis from

Most bone have only one nutrient artery and nutrient vein (femur have more)

What is the metaphyseal vessels?

Supply the blood to inner surface of each epiphyseal cartilage

What is the periosteal vessels?

Supply the blood to secondary ossification centers

What does bone growth and development depend on?

The balance between bone formation and bone resorption

What is remodeling?

The ongoing process of tearing down and rebuilding bone matrix

The process of remodeling continuously recycles and renews the organic and mineral components of the bone matrix

What is the turnover rate of remodeling?

Young adults, 1/5 of skeleton is recycled and replaced each year

What factors have the most important effects on the process of the bone remodeling?

Exercise

Nutrition

Hormones

What is exercise involved in with the bone remodeling process?

Lack of exercise could result in porous and weak bones

Which types of nutrition is involved in the bone remodeling process?

Minerals and vitamins

What types of hormones are involved with the bone remodeling process?

Calcitriol

Growth hormone

Thyroxine

Sex hormones

Parathyroid hormones

Calcitonin

Why are minerals essential components of the bone remodeling process?

Large amounts of calcium and Phosphorus
Smaller amounts of magnesium, fluoride and manganese

Required for bone growth and remodeling

What are the types of vitamins that are essential to the bone remodeling process?

Vitamin A , C , D, K, B12

What is vitamin A used for in the bone remodeling process?

Stimulates activity of osteoblasts

What is vitamin C used for in the bone remodeling process?

Synthesis of collagen

What is vitamin D used for in the bone remodeling process?

Essential to healthy bones because it promotes the absorption of calcium from foods in the gastrointestinal tract into the blood

What is vitamin K and B12 used for in the bone remodeling process?

Synthesis of bone proteins

What is calcitriol hormone used for in the bone remodeling process?

Kidneys

Increases calcium and phosphate ion absorption by the intestines of the digestive tract

What is the growth hormone used for in the bone remodeling process?

Stimulates osteoblasts activity and the synthesis of bone matrix

What is the thyroxine hormone used for in the bone remodeling process?

Thyroid gland (follicle cells)
Growth hormone stimulates osteoblast activity and the synthesis of bone matrix

What is sex hormones used for in the bone remodeling process?

Ovaries (estrogen) / Testes (testosterone)

Stimulate osteoblast activity and the synthesis of bone matrix; estrogen stimulates epiphyseal closure earlier than testosterone