Skeletal System Part 1

Long bone: examples

femur, tibia, fibula, humerus, radius, ulna, phalanges

Compact bone

- 80% of skeleton - few spaces - make up external layer of all bones - bulk of diaphysis - provides protection, support, resists stresses of weight and movement

Types of cells in Bone Tissue

- osteoblasts - osteocytes - osteoclasts

Diaphysis

- growing between - bone shaft or body - long cylindrical main portion

Epiphyses

- growing over - distal and proximal ends

Microscopic structure of bones

- abundant matrix, widely-spaced cells - 25% water, 25% collagen fibers, 50% mineralized salts - hardness depends on crystallized inorganic salts - flexibility depends on collagen fibers (rods in concrete)

Storage ex.

- bones contain a matrix that contains calcium phosphate - fat stored in yellow bone marrow

Effects of Aging

- cartilage/bone deteriorate - cartilage calcifies (hard/brittle) - articular cartilage may no longer function (osteoarthritis)

Irregular bone: definition

- complex shape (hard to fit into other categories) - varied shapes that permit connections with other bones

Projections for muscle attachment

- crest - spine - trochanter - tubercle - tuberosity

Depressons and Openings

- foamen - fossa - meatus - sinus

Flat bone: definition

- generally thin - 2 parallel surfaces - gives protection and surface area for muscle attachment

Long bone: definition

- longer in length than width - consists of a shaft and a variable number of ends - somewhat curved for strength

Support ex.

- lower limbs support entire body - pelvic girdle supports abdominal cavity

Medullary cavity

- marrow cavity - space within the diaphysis for marrow storage - primarily fatty yellow bone marrow in adults

Short bone: definition

- nearly equally in length and width - somewhat cube shaped

Remodeling...

- old bone replaced by new bone - thickness of bone changes over time - caused by physical use, stress, and strain

Compact bone elements

- osteons - lamellae - central canals - osteocytes - lacunae - canaliculi

In newborns, all marrow is...

- red bone marrow and involved in hemopoiesis - changes from red to yellow as age increases

Metaphyses

- regions on a mature bone where diaphysis joins the epiphyses - growing bones contain an epiphyseal plate - as growth stops, cartilage is replaced by bone (epiphyseal line/disc)

Protection ex.

- skull protects brain - ribs protect heart/lungs

Mineral homeostasis of the skeleton...

- stores minerals (calcium/phosphorus) - release minerals into blood stream on demand to maintain and distribute to certain organs

Endosteum

- thin membrane lining medullary cavity - contains a single layer of bone forming cells

Articular cartilage

- thin, hyaline cartilage covering epiphysis where bones fom joints with other bones - reduces friction/absorbs shock - no perichondium - damage repair limited

Periosteum

- tough sheath of dense irregular connective tissue surrounding bone surface - contains bone forming cells to enable bone to grow in diameter - protects bone, assists in fracture repair, nourishes bone tissue, attachment point for ligaments and tendons

Basic bone anatomy

1. diaphysis 2. epiphyses 3. metaphyses 4. articular cartilage 5. periosteum 6. medullary cavity 7. endosteum

Repair

1. hematoma 2. fibrocatilage callus 3. bony callus 4. remodeling

Types of bone

1. long 2. short 3. flat 4. irregular 5. round

Bone Growth/Development

1. middle of the bone 2. osteoblasts deposit bone 3. bone is reabosrbed by osteoclasts to form a medullary cavity 4. secondary ossification center form in the epiphyses 5. eventually disk ossifies

Functions of the skeleton

1. support for the body 2. protection of soft body parts 3. production of red blood cells 4. storage of minerals and fats 5. permission for flexible body movement

___ bones in the adult human body

206

What is bone length dependent on?

How long the epiphyseal disk remains in active division

Where is the primary ossification center?

Middle of the bone

Foramen

a rounded opening through a bone EX: foramen magnum

Spongy bone

aka cancellous bone - no osteons - have trabeculae (which support/protect bone marrow) - spaces filled with red bone marrow - form most of epiphyses of long bones and narrow rim around medullary cavity of diaphysis - most of bone tissue of short, flat, and irregular bones - lighter weight than compact, moves more easily when pulled by skeletal muscle

Short bone: examples

carpals, tarsals

During prenatal development, most skeleton is...

cartilage

Lacunae

cavities that contain osteocytes around in concentric circles called lamellae

Sinus

cavity or hollow space in the bone EX: frontal sinus

Osteopor. inceases in women due to the reduction of ________ levels in menopause

estrogen

Hematoma

blood escapes from vessels, forms clot; inflamation

Cartilage converts to _____ when mineral salts are added

bone

Comminuted

bone breaks into several fragments

Osteoblasts

bone builders - secrete matrix - don't undergo cell division - trap themselves in their own secretions and become osteocytes

Oblique

bone is broken at an angle

Transverse

bone is broken into two pieces on a tranverse plane

Linear

bone is broken logitudinally but NOT separated into two parts

Processes

bony prominence or knob; often forms a joint with a fossa EX: olecranon process of the ulna

Osteoclasts

break down bone - huge cells from fusion of monocytes - concentrated in the endosteum - release enzymes and acids to digest matrix - called resorption - part of normal development, growth, maturation, and repair of bone

Fracture

break in a bone

Greenstick

break on the outer arc of the bone is incomplete

Simple

broken bone doesn't pierce skin

Compound

broken bone end pierces skin

Impacted

broken ends of bone are wedged into each other

Round bone: definition

circular

Osteons/Haversian systems

circular/cylindrical shaped units of compact bone

Central canals

contain blood vessels and nerves which bring blood to osteocytes

Endochondal ossification

conversion from cartilage to bone

Flat bone: examples

cranial bones, sternum, ribs, scapula

Red bone marrow consists of...

developing blood cells, adipocytes, fibroblasts, and macrophages

Red bone marrow present in...

developing fetuses and some adult bones: pelvis, ribs, sternum, vertebrae, skull, ends of arm and thigh bones

2 main parts of a long bone

diaphysis and epiphysis

Spiral

due to twisting of bone, bone is ragged

Fossa

flattened or shallow surface EX: mandibular fossa

Trabeculae

irregular lattice work of thin columns of bone

Articulation

joining of bones together at a joint, allows movement

Tuberosity

large, roughened process EX: Radial tuberosity of radius

Condyle

large, rounded, articulating knob EX: mandibular condyle

Epiphyseal plate

layer of hyaline cartilage that allows the diaphysis to grow in length

Yellow bone marrow is...

mainly adipose cells with few blood cells

Osteocytes

maintain tissue - maintain daily bone metabolism (exchange of nutrients and waste) - don't undergo cell division

Trochanter

massive process found only on the femur EX: greater/lesser trochanter of femur

Crest

narrow, ridge-like projection EX: Iliac crest of coxal bone

Production of blood cells

occurs in red bone marrow (connective tissue)

Each bone is an ____

organ, composed of bone, cartilage, dense connective, epithelium, adipose, nervous, blood (forming tissue)

By 30, bone reabsorption by osteoclasts exceeds new bone synthesis by ___

osteoblasts

Remodeling

osteoblasts build new compact bone at the periphery; osteoclasts reabsorb the spongy bone and build a new medullary cavity

Bony callus

osteoblasts produce trabeculae of spony bone and convert the fibrocartilage to bone; joins the pieces together

Round bone: example

patella

Head

prominent, rounded, articulating proximal end of a bone EX: head of the femur

Red bone marrow produces...

red blood cells, white blood cells, and platelets through hemopoiesis or hematopoiesis

Production ex.

red bone marrow of fetal bones and certain adult bones produce blood cells

Spine

sharp, slender process EX: Spine of the scapula

Compact/Spongy bone is categorized upon...

size and distribution of spaces

Canaliculi

tiny canals between cells that allow nutrients from the blood to reach all of the cells

Tubercle

small, rounded process EX: Greater Tubercle of humerus

The skeletal system is...

the entire framework of bones and cartilage

Osteology

the study of bone structure and treatment of bone disorders

Lamellae

thin layers (concentric circles around central canals) that form the matrix of osteons

Fibrocartilage callus

tissue repair begins; fibrocartilage fills space between bones; collagen fibers tie the ends of bones together

Perichondrium

tissue that surrounds hyaline and elastic cartilage - has blood vessels in it

Meatus

tubelike passageway through a bone EX: external auditory meatus

Irregular bone: examples

vertebrae, some facial bones

Osteoporosis

weak, thin bone, cause pain and tends to fracture easily - bones more porous, but matrix is harder = brittle - take longer to heal when broken

Articulating surfaces

where bones meet (joints)