Skeletal system

origin of adult bones

cartilage and fibrous membrane

Cartilage composition

most water abd lacks blood vessels and nerves

Types of cartikage

Hyaline, Elastic, Fibrocartilage

7 functions of bone

Support, Protection, movement, mineral/growth factor storage, triglyceride storage, hormone production,

Axial skeleton

Skull, Spinal column, Thoracic cage

functions of axial skeleton

Forms longitudinal axis of the body, Supports the head, neck and strunk, Protect brain, spinal cord, and organs in the thorax

appendicular skeleton

Upper limbs, Lower limbs, Pectoral girdle, Pelvic girdle

appendicular skeleton function

movement

4 classifications of Bone

long, short, flat, irregular

Long bones

Longer than wide

Shaft and two ends bones are often expanded

all limb bones except patella, wrist, and ankle

flat bones

Thin flattened and often slightly curved. Ex sternum

short bones

Approx. Cube shipped that vary in size and number. Bones of wrist and ankle

irregular bones

Complex shapes, e.g., vertebrae.

spongy bone (trabecular bone)

needle-like bone(trabeculae), lighter than compact bone, spaces between trabeculae are occupied by bone marrow

compact bone (cortical bone)

dense outer layer of every bone, many passage waves for nerves and blood

functional unit of compact bone

osteon (haversian system)

Lamellae

Composed of nested tubes of bone matrix that form osteons.

Collagen fibers and lamellae

All collagen fibers run in the same direction in one lamella.

Fibers in adjacent lamella run in different directions: resisting twists

Haversian Canal

runs down the center of each osteon containing blood vessels and nerves

interstitial lamellae

incomplete lamellae between intact osteons that fill in the gaps.

Lacuna

spaces in the bone that house osteocytes

Canaliculi

narrow canals that connect lacunae

Circumferential lamellae

run the entire circumference of the bone- belt around the osteons

Volkmann's canals

Connect nerve/blood supplies from periosteum to the Haversian canals & medullary cavity

structure of short, irregular, and flat bones

Plate of spongy bone covered by compact bone, lacks a shaft or bone ends, no well-defined marrow cavity

general structure of long bone

Diaphysis with marrow cavity, spongy bones in epiphyses(bone ends), membranes, and Projections, depressions, and openings along the length of the bones

Epiphysis

broader than the shaft and is a joint forming surface covered with hyaline cartilage

Epiphyseal line

Remnant of the epiphyseal plate (growth plate) where elongation happens

medullary cavity (marrow cavity)

located in the center of the diaphysis

marrow and aging

as we age red marrow is replaced by yellow marrow

Periosteum

White double layered membrane that covers external bone

Periosteum composition

outer layer= fibrous, irregular, connective tissue

Inner layer = osteogenic(stem) cells

function of periosteum

Rich supply of nerves and blood vessels

Anchoring points for tendons and ligaments

Sharpey fibers

hold periosteum on the bones

Endosteim

Membrane covering internal bone surfaces that contains osteogenic cells

Bone marking functions

Membrane covering internal bone surfaces, conduits for nerves and blood vessel

two types of bone marking

Projection and depression/ opening

function of depressions and opening

Nerve and blood vessel passages

Crest

narrow ridge of a bone

spine

sharp and pointy coming from a surface of a bone

process

any bone prominence

Ramus

handle/arm like a bone

Foramen

round oval opening through a bone

Meatus

canal like passageway

Sinus

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

Osteogenic cell

a stem cell located in the periosteum and endosteum capable of becoming an osteoblast or bone lining cell

Osteocytes

mature bone cells in a lacunae that monitors the bone matrix by communicating with Osteocytes

Bone lining cells

Help maintain bone matrix found on the surface of bones, not being remodeled

Osteoblast

Matrix synthesizing cells that help in matrix calcification

Osteoclast

A large, multinucleated cell that breaks down bone

Osteoid

organic part of bone matrix secreted by osteoblasts that makes the ground substance and collagen

hydroxyapatite

inorganic bone matrix, made of mineral salts, mainly calcium phosphates, that are packed crystals around the collagen fibers

Giving bone its hardness

Ossification(osteogenesis)

Process of bone formation. Cartilage and fibrous membrane to bone

intramembranous ossification

Bone develop from fibrous membranes forming membrane bone and forms the bones of the skull and the clavicle

Endochondrial ossfication

Replace cartilage with bone. Forms all other bones. More complex method

bone growth by length

Happens at epiphyseal cartilage pushing the epiphysis away from the diaphysis, pushing the top of the bone away by elongating the shaft

bone growth by width

Happens in response to environmental pressure = appositional growth

growth hormone for bone growth in length

Growth hormone is the most important stimulus of epiphyseal plate growth

sex hormone for bone growth in length

sex hormone: Promotes growth spurts in adolescence

Promotes masculinization or feminization of the skeleton

Stimulates epiphyseal closure: no more growth in length

bone remodeling

Controlled by calcium homeostasis and mechanical/gravitational force on the skeleton

timeline of bone remodeling

Every 3-4 years, spongy bone is replaced

Every 10 years, compact bone is replaced

osteoblast process

Osteoblasts make new matrix triggered by Levels of calcium and phosphate and calcium-binding matrix proteins

osteoclast process

Secretes lysosomal enzymes and H+ that digest bone

Acidity makes Ca salts soluble

phagocytose matrix material and dead osteocytes

role of calcium

Transmission of nerve impulses

Muscle contraction

Blood coagulation

Cell division

Cell signaling pathway in the mitosis pathway

Regulation of Calcium

Parathyroid hormone, released from the parathyroid in the thyroid gland stimulate release of calcium from bones when levels in the blood drop

presence of calcium

99% in the bones

1200-1400g

Need vitamin d for calcium uptake

wolff's law of bone remodeling

Curved bones thicken where they are likely to buckle

Trabeculae of curved bone organize into lines of compression

Large bony projections develop where large active bone is attached

how mechanical force remodels bone

Deforming a bone produces an electrical current

Hormonal controls determine whether and when remodeling happens

Mechanical stress determines where remodeling occurs

position of fractures

Non-displaced- bone in normal position

Displace- bones out of alignment

completeness of fractures

Complete- broken all the way through

Incomplete-broken fracture

penetration of skin of fractures

Open (compound)- through the skin

Closed (simple)- skin not broken

treatment of fractures

Reduction: realignment of broken bones by surgey(open) or manuel(closed) or immobilization

Comminuted fracture

bones in 3 or more pieces

spiral

curved around the perimeter of the bone

depression

pressed inward

compression

weakening of the bone is crushed

Greenstick

doesn't break all the way

repair of simple fracture steps

1. Hematoma forms(blood pools)

2. Fibrocartilaginous callus forms

3. Bony callus forms

4. Bone remodeling occurs

Paget's disease

Excessive and haphazard bone deposition and resorption. Reduced mineralization=spotty weakening

ostemalacia(rickets)

soft bone caused by insuffiecient calcium and vitamin D

Osteoporosis

common issue where resorption happens faster than deposition and bones become porous and light

Osteosarcoma

Bone cancer at the end of the bone that causes easy fracture, joint pain