W10 Skeletal System Flashcards
Describe the functions of the skeletons and bone tissues?
The skeletal system has a number of important functions:
Support
Protection
Assistance in moving
Mineral homeostasis
Blood cell production
Triglyceride storage
Describe support in the skeletal system
Provides a structural framework for the soft tissues of the body
Describe protection in the skeletal system
The skeleton protects internal organs
Describe assistance in moving
Movement of the skeletal muscle attaches to bones, assist in contraction
Describe mineral homeostasis
Osseous tissue stores severval minerals (calcium & phosphorous, bones can release minerals to maintain homeostatic levels
Describe Blood cell production
Blood cells are produced by red bone marrow, which is found in certain bones
Describe Triglyceride storage
Yellow bone arrow consists mainly of adipocytes that store triglycerides
Describe the gross anatomy of a typical long bones
Epiphysis (bone end) ↓ Diaphysis (bone shaft) ↓ Epiphysis (bone end)
What are the 6 classifications of bones?
Long bone
Short bone
Flat bone
Irregular bone
Sesamoid bone
Sutural bones
Describe bone tissue
A unique form of hard connective tissue. Collagen fibres and mineral salt crystals (Ca & phosphate) = hydroxyapatite. Bones arr composed of two structures compact (cortical) & spongy (cancellous) bone (Spongy bones contain myeloid tissue)
Describe the gross anatomy of a typical long bone of the Epiphysis region
Articular cartilage - thin layer of cartilage that covers the surface of the epiphysis that articulates with other bones
Metaphysis- Between diaphysis & epiphysis.
Contains the epiphyseal growth plate in growing bones
Describe the gross anatomy of a typical long bone in the Diaphysis reigon
Endosteum - a thin connective tissue layer that lines the surface of the medullary cavity
Medullary cavity - A hallow clindrical space within the middle of the diaphysis. Contains yellow bone marrow in adults
Periosteum - a connective tissue layer attached to the outside of the bone
Describe the structure of a flat bone
Structure of a flat bone similar to a long bone but simpler
Describe the blood supply in bone
Bone is a living tissue so it contains an extensive network of blood vessels. These vessels overlap so if one becomes damaged the bone will not die because it receives blood from another vessel
Describe the chemical composition of the bone
Osseous tissue is a type of connective tissue, it contains cells that are surrounded and embedded within a extracellular matrix. Composed of 25% water 24% collagen fibers 50% crystallized mineral salts
What are the cells of osseous tissue?
Osteoprogenitor (osteogenic) Osteoblasts Osteocytes
Define Osteoprogenitor cells
They are unspecialized stem cells, they are the only bone cells that can divide. Important in fracture repair
Define Osteoblasts
Synthesis and secrete collagen fibres and other components of the extracellular matrix.
They initiate calcification - bone formation also know as ossification
Define Osteocytes
Mature bone cells and most numerous cells. Responsible for day to day function of metabolism of osseous tissue.
Exchange aided by cytoplasmic projections in canaliculi (little canals, caneloni) FORMED WHEN OSTEOBLASTS BECOME SURROUNDED WITH BONE MATRIX
Define Osteoclasts
Large multinucleate cells, release enzymes and acids that digest the extracellular matrix. Involved in resorption of osseous tissue (important for development, maintainance and repair)
Describe the histology of a compact &spongy bone
Compact bone: diaphysis of long bones, surface of short, flat and irregular bones
Spongy bone - epiphysis of long bone, most of short flat and irregular bone.
Describe the histology of a compact bone structure
Compact bones contains very few spaces. It provides protection and support and resists stress of weight and movement.
Its ↑ tensile strength is due to the type of materials and how its arranged
What are the components of bone structure?
Osteon - repeating structural unit of compact bone. Consist of a central canal containing blood vessels surrounded by concentric lamellae, osteocytes, lacuna and canaliculi.
Concentric lamellae (thin layer) - rings of hard, calcified extracellular matrix
Lacuna - small space located between the lamellae, these spaces contain osteocytes
Canaliculi - small channels filled with cellular projections & extracellular fluid that radiate from lacuna, provides routes for oxygen and nutrients to each osteocytes
What are the two types of canals in compact bone structure?
Central canals - run though the centre of osteons & connect with perforating canals, surrounded by concentric lamellae
Perforating canals - allow blood vessels, lymphatic vessels and nerves to enter compact bone
What are the differing lamellae (layers) of compact bone?
Interstitial lamellae - areas between osteons, also contain lacuna, canaliculi, & osteocytes. Contain fragments of old osteons that have been broken down during bone remodeling.
Circumferential lamellae - Lamellae that surround the rest of the bone
Describe the histology of spongy bone
Contains lamellae that are arranged into colums called trabeculae. These spaces make this tissue light
Define trabeculae
Contain osteocytes within lacuna, canaliculi connect lacuna. Trabeculae orientate towards lines of stress.
Describe bone formation
There are two methods of bone formatiom during embryonic development:
Intramembranous ossification- flat bones of the skull and mandible
Endochondral ossification: involves the replacement of cartilage with osseous tissue
Describe endochondral ossification
Mesenchymal (stem) cells of the embryo come together (condense) and differentitate into chondroblasts that produce a hyline cartilage model of the future bone.
Cartilage is mineralised and remodeled to produce bone
Describe how epiphyseal plates allow long bones to grow
Mesenchymal cells cluster together and condense form a modle of the future bone
→ These develop into chondroblasts that produce hyaline cartilage model of the bone
→ hyaline cartilage is mostly type II collagen and chondroitin → chondroblasts turn into chondrocytes
→ cartilage grows & chondrocytes undergo hypertrophy (larger) and burst which lead to calcification
→primary ossification centre a nutrient artery penetrates into the calcifying cartilage model &; stimulates production of osteoblasts = osseous tissue spreads
→ osteoclasts breakdown some of the newly fored bone @ the medullary cavity
→ development of secondary ossification centre (no medullary cavity forms in this reigon)
→ formation of articular cartilage and epiphyseal plate to cartilage articulation
How do long bones grow after birth?
Long bones continue to lengthen until adolescene, through additional bone tissue at the epiphyseal plate.
Also increase in wirth through appositional growth. On the epiphyseal side of the epiphseal plate, cartilage is formed.
On the disaphysis side cartilage is ossified and the diaphysis grows in length
Describe on a cellular level how bone grows and lengthens
Resting zone - nearest the epiphysis. Anchors epiphyseal plate to the epiphysis.
Proliferating zone: chondrocytes are dividing and producing cartilage
Hypertrophic zone - chondrocytes mature and expland
Calcification zone - matrix calcifies chondrocytes die Ossification zone - osteoblasts replace the calcified cartilage with ossesous tissue
What are the factors affecting bone growth?
Adequate diety intake of minerals and vitamins.
Calcium, phosphorous, fluoride, magnesium, iron,
Vita A, C, B12, D and K,
Weight bearing exercise,
insulin-like growth factor
Describe the process of bone remodelling
Refers to the ongoing replacement of old osseous tissue by new osseous tissue . Osteoclasts breakdown the extracellular matrix and then osteoblasts replace it with new extracellular matrix
What is the function of bone remodelling?
Renews old osseous tissue before deterioration sets in. Distrubutes bone extracellular matrix along the lines of mechanical stress
Name the two principal divisions of the adult skeleton
Axial skeleton - central core of the body including vertebrae, head and trunk
The appendicular skeleton - appendages and support structures including bones of the limbs, hips and shoulders
Describe the two major types of markings found on bone surfaces
Depressions & openings - allow the passage of soft tissue (blood vessels/nerves)
Processes - projections or outgrowth that help form joints or serve as attachment points for ligaments and tendons
Identify the component of the axial skeleton
Atlas & axis Cervical (7) Thorasic (12) Lumbar (5) Saccrum (5) Coccyx
Identify the components of the appendicular skeleton
- Frontal bone of skull
- Parietal bone of skull
- Temporal bone of the skul
- Occipital bone of the skull
- Vertebrae collum regions
- Vertebral cody - vertebral foramen, spinous process and transverse process C1 ( atlas) C2 (axis)
- Sacrum
- Sternum
- Clavicle
- Scapula
- Humerus
- Radius
- Ulna Carpals, metcarples, phalanges
- Hip bone
- Femur
- Patella
- Tibia
- Fibula
- Tarsals, metatarsals, phalanges of foot
What is an articulation ?
Points of contact between two bones, bone and teeth , bone and cartilage
How do you classify articulations based on movement?
Based on the degree of movement, into three categories: Synarthroses - immovable joints Amphiarthroses - slightly moveable Diarthroses - a freely moveable joint
Name and describe articulations based on their structure
Fibrous joints - bones held together by dense connective tissue Cartilaginous joints - bones are held together by cartilage Synovial joints - there is a synovial cavity and bones are held together by an articular capsule
Define fibrous joints and provide examples
Sutures - bone of the skull held together by a thin layer of connective tissue.
Syndesmoses - fibrous bands connect two bones (tibia and fibia) (amphiarthroses)
Gomphoses - PDL attaches tooth to socket (synarthroses)
Define Cartilaginous joints
Synchondroses where the connection between bones is formed by hyaline cartilage (epiphysis to diaphysis = Synarthroses
Symphyses - where a broad flat disc of fibrous cartilage connnects to bones
Define Synovial joint
Characterised by a synovial cavity between articulating bones, allows cavity to freely move. (Diarthroses) Includes:
Articular cartilage - lines the surface of the articulating surfaces of bone,
Synovial fluid - secreted by the synovial membrane, contains hyaluronic acid. Acts to reduce friction, absorb shocks, supply nutrients & remove wastes
What are the 6 types of synovial joints?
Pivot joint Gliding joint Condyloid Ball and socket Saddle joint Hinge joint
Define pivot joint
Only allows rotation around its own axis. (cc1,c2 - atlas axis)
Define hinge joint
Produce angular open and closing like a door hinge
Define saddle joint
Allows movement around 3 axis, side to side, up and down, and rotation
Define Planar/gliding joints
Flat or slightly curved. Side to side, back and forth gliding movement
Define Condyloid joint
Allows movement around 2 axes, up and down, side to side
Define Ball and socket joint
Allows movement around all three axes and in all directions
