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Skeletal System/Joints/Skeletal Muscle (Skeletal System/Tissues (Major…
Skeletal System/Joints/Skeletal Muscle
Skeletal System/Tissues
Major functions
Protection
Cranium, rib cage, vertebrae.
Mineral storage
Calcium + Phosphate.
Movement
With help of muscle.
Blood cell formation
Red bone marrow
Support
Framework for connection of soft tissues.
Tendons - muscle to muscle - dense regular connective tissue.
Ligaments - bone to bone - dense regular connective tissue.
Energy storage
Yellow bone marrow - fat
Major structural components
35% organic
Cells + extracellular matrix - collagen --> strength + flexibility
65% inorganic
Mineral
Hardness
Resists compression
Compact bone
Location
Outer part of everybone
Structure
Composed of osteons packed together.
Articular cartilage
Periosteum (composed of dense irregular connective tissue)
Endosteum.
Spongy bone
Location
Ends of long bones.
Inside all other bones.
Structure
NO osteon
Trabeculae
Osteocytes
Extra cellular matrix
Location of red bone marrow
Types of bones based on shape
Long bone (humerus)
Short bone (talus)
Flat bone (Sternum)
Irregular bone (vertebra)
Long bone
Components
Proximal epiphysic
Diaphysis
Distal epiphysis
Articular cartilage
Periosteum - 2 layers - outer layer is dense irregular C.T - inner layer is osteogenic bone (creation or formation).
Sharpey's fibers hold periosteum tightly to bone.
Endosteum
Spongy bone
Red marrow (in spongy bone)
Epiphyseal line
Medullary cavity
Yellow marrow
Nutrient artery
Red marrow
Composition
Gelatinous material as embryo/fetus
Function
Contains blood-forming stem cells.
Location
Fills all spaces inside the bone
Yellow marrow
Composition
Fat
Location
Found about age 7 in vertebrae, coxal bones, sternum, ribs and skull.
Function
Energy storage
Contains mesenchymal stem cells producing fat, cartilage, bone.
Types of bone cells
Osteogenic cells (stem cells)
Location
Deep layers of periosteum and marrow.
Function
Develop into osteoblasts
Osteoclasts
Location
Bone surfaces and at sites of old, injured, unneeded bones.
Function
Bone resorption (microvilli perform phagocytosis to break down organic portion of bone tissue. Inorganic (mineral) back to blood).
Secretes enzymes.
Structure
Created from leukocytes that form one big cell - multinucleate.
Microvilli: break down bone tissue and secretes enzymes.
Osteoblasts
Location
Growing portions of bone, including periosteum and endosteum
Function
Bone formation
Making extracellular matrix
Osteocytes
Location
In lacuna
Function
Maintains bone tissue
Joints
Fibrous joints
Syndesmosis
Bundles of dense regular connective tissue.
Distal tibiofibular joint - carpals/tarsals.
Little movement.
Gomphosis
Between teeth and alveoli.
Periodontal ligaments.
Suture
Bones joined by very short interconnecting fibers.
Only skull.
No movement.
Cartilaginous joints
Synchondrosis
Epiphyseal plate, between first rib and manubrium (hyaline cartilage).
Immoveable.
Symphysis
Pubic symphysis.
Intervertebral joints.
Hyaline + fibrocartilage.
Slightly moveable.
Synovial joints
Major structural components
Presence of joint cavity surrounded by a joint capsule.
Joint capsule has 2 layers:
Outer layer: dense irregular connective tissue - attaches to periosteum.
Inner layer: synovial membrane - mostly areolar connective tissue - secretes synovial fluid.
Function:
Slippery and lubricating.
Shock absorption.
Nourishes the articular cartilage.
Bursa (e): sac filled with synovial fluid between:
Tendon + bone
Skin + bone
Ligament + bone
Muscle + bone
Type of bursa - tendon sheath
Six structural types
Plane joint
Nonaxial movement - gliding movement.
Eg: Intercarpal joints, intertarsal joints, joints between vertebral articular surfaces.
Hinge joint
Uniaxial movement - flexion and extension.
Eg: Elbow joints, interphalangeal joints.
Pivot joints
Uniaxial movement - Rotation
Eg: Proximal radioulnar joints, atlantoaxial joint
Condylar joint
Biaxial movement - flexion and extension; adduction and abduction.
Eg: Metacarpophalangeal joints, wrists joints.
Saddle joint
Biaxial movement - adduction and abduction; flexion and extension.
Eg: Carpometacarpal joints of the thumbs
Ball-and-socket joint
Multiaxial movement - flexion and extension; adduction and abduction; rotation.
Eg: Shoulder joints and hip joints.
Skeletal Muscle
Functions
Open/close body passageways - sphincter muscle.
Maintain posture + Stabilize joints.
Produce movement: moves bones, blood, contents of hollow organs.
Generate heat
Properties
Excitability - ability to respond to a stimulus and producing an electrical signal.
Extensibility - ability to stretch (within limits)
Contractility: generate tension or force when pulling on an attachment point.
Elasticity - ability to return to original shape after contraction/extension.
Connective tissue layers
Perimysium: covers each fascile - dense irregular C.T; covers blood vessel within.
Epimysium - dense irregular C.T - binds fascicles together.
Composed of mostly reticular fibers - create space allows space for very small blood vessel to run next to muscle fibers.
Deep fascia - binds whole muscles together - dense irregular C.T
Skeletal fiber
Sarcolemma
Transverse (T) tubules
Sarcoplasmic reticulum
Smooth endoplasmic reticulum - storage of calcium.
Myofibrils
Muscle fibers
Mitochondria
Terminal cisterns
Storage place of calcium
Neuromuscular junction
Presynaptic terminal
Synaptic cleft (gap)
End plate region
Postsynaptic membrane (neurotransmitter's receptors)
Motor neuron