ap 3rd exam

Functions of the skeleton system? (5)

Support: structural support for body

Protection: provide protection for soft tissues and organs from injury and trauma

Movement

Hemopoiesis: production of platelets, erythrocytes, and leukocytes

Storage: stores lipids, calcium, and phosphate

Main components of the skeletal system?

Bones, hyaline cartilage, cells, ligaments, tendons, and fibrocartilage

What can bones either be?

Compact or cancellous (spongy)

Hyaline cartilage is composed of?

Collage fibers with GAGS

Places that have hyaline cartilage (4)

Articulate cartilage, costal cartilage, fetal skeleton, and epiphyseal plates

Fibrocartilage is composed of?

Collagen Fibers with proteoglycans

Where is fibrocartilage found? (3)

Pubic symphysis, intervertebral discs, and meniscus of the knee

Ligament definition and composed of what

Connects bone to bone and composed of dense regular CT

Tendon def and composition

Muscle to bone. Dense regular CT

Aponeurosis

Tendon for flat muscles

Explain the first cell path

Mesenchymal cell > osteoprogenitor cells (where bones originate) > osteoblasts > osteocyte

Why do osteoblasts turn into osteocytes?

They get stuck in the cell matrix

Second cell path

Mesemchymal cells > bone marrow cells (multiple nuclei fuse) > osteoclasts

third cell path

Mesenchymal > chondroblasts > chondrocytes

Mesenchymal

Stem cells of all CT

Osteoprogenitor

A bone stem cell

Osteocyte

A osteoblast stuck in the bone matrix that develops a mature cell that can detect mechanical stress

Osteoclast

A phagocytic cell that consumes and breaks down bone

Chrondocyte

A chondrocyte that gets stuck in the cartilage matrix and develops into a mature cell that maintains the cartilage matrix

Osteoid

AKA pre-bone

What is osteoid composed of?

Collagen fibers along with GAGS + NO WATER= more solid

What is bone composed of?

Osteoid plus hydroxyapatite

When hydroxyapatite is being laid down, it is called what?

Calcification

Articular cartilage

Piece of hyaline cartilage that covers articulating ends of bone (joints and synovial membranes)

epiphysis

Located on Both proximal and distal ends that have both compact and spongy bone

Which part of the bone contains the epiphyseal plate or line?

Metaphysis

Metaphysis

Middle area between diaphysis and epiphysis. On both ends. Has epiphyseal plate

Diaphysis is aka?

Shaft

Which part of bone has the medullary cavity?

Diaphysis

which part of bone has red or yellow bone marrow?

Medullary cavity

Perforating fibers

DICT fibers perpendicular to the periosteum to stick it to the bone

Periosteum

Outer layer of bone

Periosteum is composed of

DICT, osteoblasts, fibrous layer

Endosteum

Internal layer of medullary cavity

Endosteum is composed of?

CT, osteoclasts and osteocytes

Nutrient Foramen

Small hole where blood vessels and nerves enter into the bone - highly vascularized

Interstitial growth happens where?

The epiphyseal plate

Epiphyseal line

Fully ossified epiphyseal plates

red bone marrow is found where

Found in epiphysis of long bones and middle of flat bones

Site of hematopoiesis

Red bone marrow

Yellow bone marrow

Found in medullary cavity and used for energy storage. Can be converted to red in anemic patients and present in children

Flat bones don’t have what?

Medullary cavity or bone marrow

Diploe

Spongy bone between compact bone

External circumferential lamallae

Layer on the outside of bone - parallel to the periosteum

internal circumferential lamallae

Rings Inside of bone parallel to periosteum

Osteon

Functional unit of compact bone

Central canal

A hole in the center of an osteon where blood vessels and nerves run through

Concentric lamallae

Rings of bone that make up the osteon that house osteocytes in the lacunae

Lacunae connected together are called

Canaliculi

Canaliculi

Where osteocyte arms are house - sense pressure

Interstitial lamallae

Rings of bone between the osteons

Perforating canals

Perpendicular to central canal w blood vessels and nerves

Trabeculae

Functional unit of spongy bone that have parallel lamallae

Parallel lamallae

Rings of bone parallel w each other and have lacuna

Ossification

Bone formation

Intramembranous ossification

Type of ossification within mesenchyme membrane

Intramembranous ossification steps and acronym? (4)

OWCL. ossification, calcification, woven, and lamellar

O: ossification centers form in the thickened region of mesenchyme. Osteoblasts produce osteoids

C: osteoblasts mature into osteocytes which allow osteoid to fully ossify

W: woven (primary bone) forms as osteoblasts make trabeculae. Mesenchyme condense to form periosteum

L: lamellar (secondary) replaces woven bone as spongy and compact. Periosteum fully forms

Hydroxyapatite composed of

The concrete. Calcium + phosphate + hydroxide

Collagen

Rebar

Endochrondral ossification

Most bones. Cartilage model gradually replaced w bone

Endochrondral ossification steps

8-12 weeks: hyaline cartilage forms in fetus

Fetal period: perisoteal bone collar forms on exterior of the diaphysis

Fetal period: primary ossification center forms within diaphysis (no medullary cavity)

Newborn to child: secondary ossification center forms within the epiphysis and Metaphysis forms (very little spongy bone w small medullary cavity)

Child: bone replaces all cartilage but articles and epiphyseal plates

Teen and adult: epiphyseal plate ossifies

What makes hyaline cartilage clear

Collagen fibers w GAGS that attract water

Growth acronym?

ILAW.

Interstitial longitude apposition width

How does bone grow wider?

Osteoblasts of the periosteum produce bone while osteoclasts cut it up from the medullary cavity. Bone being made on outside

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Zones and stages of growth

Stages of growth

zone of resting cartilage: mature hyaline cartilage

Zone of proliferating cartilage: chondroblasts undergo mitotic cell division. Cells align

Zone of hypertonic cartilage: chondrocytes cease cell divison and increase in size by reabsorbing cartilage, making walls on lacuna thinner

Zone of calcified cartilage: hydroxyapatite is deposited which kills the chrondrocytes

Zone of ossification: living chondrocytes have died and osteoblasts move in to produce bone

Unions

Open: no union between epiphysis and bone (baby)

Partial: partial union between epiphysis and bone (Child)

Complete: bone is fused (adult)

W out the hydroxyapatite, bones..

Bend

W out collagen, bones..

Shatter

Bone deposition

Addition of new bone by osteoblasts

Bone resorption

Removal of old bone by osteoclasts

Mechanical stress

Osteocytes detect load or stress and communicates to osteoblasts to produce more bone

Bone most affected by stress..

Develops more mass due to mechanical stress

Growth hormone

Stimulate bone growth by epiphyseal plate (positive)

Thyroid hormone

Stimulates bone growth by increasing metabolic activity

Estrogen and testosterone

Stimulates growth w epiphyseal plate

Inhibits bone growth because of stress

Glucocorticoids

Inhibits growth by decreasing osteoblast activity or being too happy

Serotonin

Calcitonin

Decreases blood calcium lvls by promoting calcium deposition by osteoblasts

Increases blood calcium lvls by promoting calcium resorption by osteoclasts

Parathyroid hormone (negative)

Calcitrol hormone (negative)

Vitamin d. Helps absorb calcium by small intestine

A disease where insufficient vitamin D leads to decreased calcium. Bone becomes weaker and causes bow legged look

Ricketts

How the parathyroid hormone works??

Stimulus: low blood calcium lvls

Receptor: parathyroid glands detect low lvls

Control center: glands release hormone

PTH goes to kidneys to increase the production of calcitriol. Tells kidneys not to get rid of calcium in blood.

Effector: calcitriol goes to small intestine to absorb more calcium.

Calcitriol and PTH go to bones to increase osteoclast activity

Returns back to homeostasis

Osteoporosis

Disease that decreases bone mass. Includes

Post menopausal women

Smoking

Family history

Sedentary lifestyle

White woman

Cancer treatment

Losing more bone than you make

Osteopenia

A break in bone caused by disease

Pathologic fracture

Steps for bone repair

Blood vessels form from clotted blood

Fibrocartilage callus forms from chrondroblasts

Hard (bony) callus forms by osteoblasts producing trabeculae and callus

Remodel

Mnemonic for articulation function

SAD

SAD stands for

Synarthrosis: no movement

Amphiarthrosis: slight movement

Diarthrosis: freely move able

Fibrous joints composition

Dense regular and irregular CT, no cavity

Bursitis

Inflammation of bursa

Osteoarthritis

Degenerative arthritis

Rheumatoid arthritis

Autoimmune disease of joints