Anatomy Unit 2: Skeletal System and Muscle Tissue
Osteons
Repeating structural units in compact bone, consist of lamellae, central canal, lacunae, and canaliculi
Bone remodeling
Replacement of old bone with new bone, bone resorption by osteoclasts and bone deposition by osteoblasts
Periosteal arteries
Small arteries that enter the bone through the periosteum, supply periosteum and outer part of compact bone
Lacunae
Spaces between lamellae in compact bone, contain osteocytes
ECM of bone
15% water, 30% collagen, 55% crystallized mineral salts
Electrical excitability
Ability of muscle and nerve cells to respond to certain stimuli by producing action potentials
Contractility
Ability of muscle to contract forcefully when stimulated
Elasticity
Ability of muscle to return to its original length and shape
Extensibility
Ability of muscle to stretch without being damaged
Epiphyseal arteries
Arteries that enter the epiphysis, supply red marrow and tissue of epiphysis
Metaphyseal arteries
Arteries that enter the metaphysis, supply red marrow and tissue of metaphysis
Medullary cavity
Cavity within the diaphysis, contains yellow marrow and blood vessels
Canaliculi
Channels filled with extracellular fluid in compact bone, connect osteocytes with one another
Lamellae
Concentric circles of mineralized ECM in compact bone
Attachment for tendons
Connective tissue that connects skeletal muscles to bones
Endomysium
Connective tissue that penetrates the interior of each fascicle and separates individual muscle fibers
Periosteum
Connective tissue that surrounds bone, helps with fracture repair, nourishes bone tissue, and serves as attachment for ligaments and tendons
Perimysium
Connective tissue that surrounds groups of muscle fibers and separates them into bundles called fasicles
Yellow marrow
Consists of mainly adipose cells, stores triglycerides
Central canal
Contains blood vessels, nerves, and lymphatics in compact bone
Fascia
Dense sheet or band of connective tissue that surrounds and supports muscles and organs
Structure of long bones
Diaphysis, epiphysis, metaphysis, articular cartilage, periosteum, medullary cavity, endosteum
Spongy bone
Does not have osteons, consists of trabeculae, filled with red marrow
Assistance in movement
Enables movement of body parts
Hypercalcemia
Excess calcium in the blood, can be caused by over-active parathyroid or certain cancers
Stress fractures
Fractures caused by repetitive forces on the bone
Skeletal system
Framework for the body, support, protection, movement
Appositional growth
Growth in bone thickness, periosteal cells differentiate into osteoblasts and secrete collagen fibers to form ECM
Parathyroid hormone (PTH)
Hormone that increases calcium in the blood, stimulates osteoclasts and decreases calcium loss through urine
Calcitonin
Hormone that inhibits osteoclasts and speeds up calcium uptake by the bone
Osteoclasts
Huge cells derived from fusion of monocytes, release enzymes and acids that digest ECM, called resorption
Nutrient artery
Large artery that enters the diaphysis through the nutrient foramen, supplies inner part of compact bone, spongy bone tissue, and marrow
Diaphysis
Long, main portion of the bone
Hypocalcemia
Low calcium in the blood, can be caused by hypoparathyroidism or kidney disease
Mineral homeostasis
Maintains balance of calcium and phosphate in the body
Calcium homeostasis
Maintenance of calcium balance in the body, bone is major calcium reservoir
Osteocytes
Mature bone cells, maintain daily metabolism
Skeletal muscle
Muscle attached to bones, striated, voluntary
Smooth muscle
Muscle in walls of internal structures, non-striated, involuntary
Cardiac muscle
Muscle that forms the heart, striated, involuntary, has its own pacemaker
Nerve and blood supply
Muscles are well supplied with blood and nerves, somatic motor neurons stimulate contraction, proprioceptors provide information about force generated at tendons
Nerve supply
Nerves accompany blood vessels, provide sensory and motor innervation to the bone
Epimysium
Outermost layer of connective tissue that encircles the muscle
Nociceptors
Pain receptors
Hematopoiesis
Process of blood cell production
Calcification
Process of depositing mineral salts in bone tissue, initiated by osteoblasts
Red marrow
Produces red blood cells, white blood cells, and platelets
Protection
Protects internal organs
Epiphysis
Proximal and distal ends of the bone
Blood cell production
Red marrow in bones produces red blood cells, white blood cells, and platelets
Metaphysis
Region between the epiphysis and diaphysis, contains the epiphyseal line
Bone resorption
Removal of minerals and collagen fibers from bone by osteoclasts
Perforating fibers
Thick bundles of collagen that extend from periosteum to the bone
Trabeculae
Thin columns of lamellae in spongy bone, filled with red marrow
Articular cartilage
Thin layer of cartilage covering the epiphysis where bone forms joints
Endosteum
Thin membrane that lines the medullary cavity, contains bone forming cells and connective tissue
Muscle tissue
Tissue responsible for producing body movements, stabilizing body positions, generating heat, and storing/moving substances
Connective tissue
Tissue that surrounds and protects muscle tissue, includes fascia, epimysium, perimysium, and endomysium
Epiphyseal veins
Veins that accompany the epiphyseal arteries, exit through the epiphysis
Nutrient veins
Veins that accompany the nutrient artery, exit through the diaphysis
Periosteal veins
Veins that accompany the periosteal artery, exit through the periosteum
Osteogenic cells
Bone stem cells, undergo cell division and become osteoblasts
Osteoblasts
Bone-building cells, secrete collagen fibers and other components to make the ECM, initiate calcification
Store calcium and phosphate
Skeletal system stores calcium and phosphate for use in the body
Bone fracture
Break in a bone, can be closed, open, or greenstick
Bone deposition
Addition of minerals and collagen fibers to bone by osteoblasts
Proprioceptors
Sensory receptors that provide information about force generated at tendons
Compact bone
Strongest form of bone tissue, made up of osteons
Support
Structural framework for the body
Structural framework
Support for the body
Functions of the skeletal system
Support, protection, movement, mineral homeostasis, blood cell production, triglyceride storage