WK 6 100 - A&P/NC

Bone (Osseous Tissue)

A hard, dense connective tissue that forms most of the adult skeleton.

Cartilage

A semi-rigid connective tissue found in areas of the skeleton where bones move (e.g., ribcage, joints).

Functions of the Skeletal System

Supports the body, facilitates movement (in coordination with muscles), protects internal organs (e.g., ribs protect lungs and heart), produces blood cells (through haematopoiesis in bone marrow), and stores and releases minerals and fat (e.g., calcium, phosphorus, and fat stored in yellow marrow).

Support

Bones and cartilage act as a scaffold to support the weight of the body, similar to the steel beams of a building.

Facilitate Movement

Bones serve as points of attachment for muscles, transmit forces produced by muscle contractions, act as levers, and joints serve as fulcrums to enable movement.

Protection

Bones protect internal organs from injury, with specific structures like ribs protecting the lungs and heart, vertebral column protecting the spinal cord, and cranium protecting the brain.

Orthopaedist Overview

Doctors who diagnose and treat disorders and injuries related to the musculoskeletal system.

Treatment Methods

Medications, exercises, braces, and devices; some cases may require surgery.

Etymology of Orthopaedics

The word 'orthopaedics' comes from 'Ortho-' (meaning 'straight') and 'Paed-' (meaning 'child').

Prenatal Surgery

Orthopaedists have performed prenatal surgery to correct congenital defects, such as spina bifida.

Conditions Treated by Orthopaedists

Bone and joint injuries, spinal conditions such as scoliosis and kyphosis, and age-related conditions like osteoporosis.

Scoliosis

Lateral curvature of the spine, which can cause a hump under the shoulder blade.

Kyphosis

Excessive dorsoventral curvature, leading to a hunched back.

Sports Medicine Sub-specialty

Some orthopaedists sub-specialize in sports medicine, which includes treatment for simple injuries (e.g., sprained ankle) and complex injuries (e.g., torn rotator cuff).

Australian Orthopaedic Association (AOA)

A not-for-profit organization focused on specialist education and training, ensuring high standards of orthopaedic care, and supporting scientific research and humanitarian initiatives related to orthopaedics.

Reservoir for Minerals

Bone matrix acts as a storage site for important minerals, especially calcium and phosphorus, which can be released back into the bloodstream.

Calcium Ions

Crucial for muscle contractions and nerve impulse transmission.

Fat Storage

Bone tissue serves as a site for fat storage, particularly in yellow marrow.

Blood Cell Production

Bone marrow, the soft connective tissue inside most bones, is responsible for haematopoiesis (production of blood cells).

Red Marrow

The site of blood cell production (haematopoiesis).

Yellow Marrow

Contains adipose tissue (fat cells). Triglycerides in adipocytes serve as an energy source.

Body support

Bones provide the framework that supports the body's structure.

Facilitation of movement

Bones serve as attachment points for muscles, enabling movement.

Protection of internal organs

Bones protect vital organs (e.g., ribs protect the lungs and heart).

Storage of minerals and fat

Bones store essential minerals like calcium and phosphorus, as well as fat in yellow marrow.

Haematopoiesis

Bone marrow produces blood cells (red, white blood cells, and platelets).

Musculoskeletal System

The musculoskeletal system is composed of the muscular system and skeletal system, working together to support and facilitate movement in the body.

Long Bones

A long bone is cylindrical in shape, being longer than it is wide.

Examples of Long Bones

Arms: Humerus, ulna, radius; Legs: Femur, tibia, fibula; Fingers: Metacarpals, phalanges; Toes: Metatarsals, phalanges.

Function of Long Bones

Act as levers that move when muscles contract.

Short Bones

A short bone is cube-like in shape, with approximately equal length, width, and thickness.

Examples of Short Bones

Carpals (wrist bones); Tarsals (ankle bones).

Functions of Short Bones

Provide stability and support; Allow limited motion.

Flat Bones

A flat bone is typically thin but often curved.

Examples of Flat Bones

Cranial bones (skull); Scapulae (shoulder blades); Sternum (breastbone); Ribs.

Functions of Flat Bones

Serve as points of attachment for muscles; Protect internal organs.

Irregular Bones

An irregular bone does not have a clearly defined shape and does not fit into other bone classifications.

Characteristics of Irregular Bones

Typically have complex shapes.

Functions of Irregular Bones

Provide structural support; Protect vital organs, such as the spinal cord.

Examples of Irregular Bones

Vertebrae: Support the spinal cord and protect it from compressive forces; Facial bones: Many, especially those containing sinuses, are classified as irregular bones.

Sesamoid Bones

A sesamoid bone is small, round, and shaped like a sesame seed.

Formation of Sesamoid Bones

Develops within tendons, where high pressure is generated in a joint.

Function of Sesamoid Bones

Protects tendons by helping them overcome compressive forces.

Variation of Sesamoid Bones

Number and placement vary from person to person; Typically found in tendons of the feet, hands, and knees.

Example of Sesamoid Bones

The patellae (singular: patella) are the only sesamoid bones found in all people.

Skin

An organ made of tissues performing critical functions.

Integumentary System

Skin and accessory structures providing body protection.

Epidermis

Outer skin layer, avascular, made of epithelial cells.

Thin Skin

Has four layers, found on most body parts.

Thick Skin

Contains five layers, found on palms and soles.

Keratinocytes

Cells producing keratin, found in all layers except stratum basale.

Keratin

Intracellular protein providing hardness and water resistance.

Stratum Basale

Deepest epidermal layer, attaches epidermis to dermis.

Basal Cells

Cuboidal stem cells, precursors to keratinocytes.

Dermal Papillae

Finger-like projections enhancing epidermis-dermis connection.

Stratum Spinosum

Layer with spiny appearance due to desmosomes.

Desmosomes

Interlocking structures strengthening cell bonds.

Langerhans Cells

Dendritic cells acting as macrophages in skin.

Stratum Granulosum

Layer where keratinocytes begin to die and keratinize.

Stratum Corneum

Outer layer of dead keratinized cells.

Stratum Lucidum

Fifth layer in thick skin, between granulosum and corneum.

Merkel Cells

Sensory receptors for touch, abundant in hands and feet.

Melanocytes

Cells producing melanin, protecting against UV damage.

Fingerprints

Unique patterns formed by stratum basale and dermal papillae.

Avascular

Lacking blood vessels, characteristic of the epidermis.

Cell Life Cycle

Keratinocytes in stratum corneum are dead and slough away.

Basement Membrane

Thin layer separating epidermis from dermis, formed by collagen.

Keratinocyte

Cell type that synthesizes keratin in skin.

Stratum Spinosum

Layer where keratinocytes begin keratin synthesis.

Water-repelling Glycolipid

Prevents water loss, enhances skin waterproofing.

Stratum Granulosum

Layer with three to five flattened keratinocyte layers.

Keratohyalin

Protein contributing to grainy appearance in skin.

Cell Death

Nuclei disintegrate, leaving keratin and membranes.

Stratum Lucidum

Translucent layer found in thick skin areas.

Eleidin

Clear protein in stratum lucidum, aids transparency.

Stratum Corneum

Most superficial layer, protects against environment.

Keratinization

Process of increased keratin in skin cells.

Dermis

Core layer beneath epidermis, contains blood vessels.

Papillary Layer

Upper dermis layer with loose connective tissue.

Dermal Papillae

Finger-like projections into the epidermis.

Meissner Corpuscles

Touch receptors in the papillary layer.

Reticular Layer

Lower dermis layer with dense connective tissue.

Fibroblasts

Cells producing collagen and elastin fibers.

Lymphatic Capillaries

Part of immune system in the dermis.

Phagocytes

Defensive cells combating skin infections.

Keratin

Fibrous protein forming major part of skin.

Mechanical Protection

Stratum corneum prevents abrasion to deeper layers.

Cell Renewal

Stratum corneum cells shed and replaced every 4 weeks.

Microdermabrasion

Cosmetic procedure removing upper stratum corneum layers.

Reticular Layer

Dense connective tissue beneath the papillary layer.

Elasticity

Ability of skin to stretch and return.

Collagen Fibers

Provide structure and tensile strength to skin.

Hypodermis

Layer connecting skin to underlying tissues.

Adipose Tissue

Fat storage layer in the hypodermis.

Adipocytes

Cells responsible for fat storage.

Body Mass Index (BMI)

Measure of body fat based on weight and height.

Melanin

Primary pigment influencing skin color.

Eumelanin

Black and brown pigments of melanin.

Pheomelanin

Red pigment variant of melanin.

Melanocytes

Cells producing melanin in the epidermis.