Skeletal Tissue Flashcards
Frequently occurs as a disk-shaped segment of cartilage between bones and where is it located?
Fibrocartilage
- Intervertebral discs
- Pubic symphysis
- Menisci of the knee joint
- Distal radioulner joint
- Temporomandibular joint
Which is the strongest of the three types of cartilage
Fibrocartilage
Which cartilage has no perichondrium
Fibrocartilage
Has neurons bundles of branching elastic fibers within the cartilage matrix
Elastic cartilage
Where is elastic cartilage found?
- External ear
- External auditory canal
- Epiglottis
- Walls of the auditory tubes
What is bone matrix made out of?
- Water
- Collagen
- Hydroxyapatite (calcium phosphate, calcium carbonate)
Stem cells that can divide and differentiate into osteoblasts
Osteogenic cells
Secrete bone matrix; become osteocytes
Osteoblasts
Mature bone cells; regulate the composition of bone matrix
Osteocytes
Release enzymes that digest bone matrix for remodeling of bone
Osteoclasts
Two types of bone tissue
- Compact bone (cortical bone)
- Spongy bone (cancellous bone, trabecular bone)
Both types may be present within the same bone
Most of the skeleton is what type of bone tissue
Compact bone
Characteristics of compact bone
- Contains few spaces
- Forms the external layer of all bones
- Makes up the bulk of the diaphyses of long bones
- Provides protection and support, and resists stresses produced by weight and movement
The process of converting a fibrous connective tissue or cartilaginous model into bone
Ossification
Two methods of bone formation
Intramembranous
Endochondrial
Bone forms within a fibrous connective tissue membrane
Intramembranous
Bone forms within a hyaline cartilage model
Endochondral
Bone remodeling is the ongoing replacement of old bone tissue by new bone tissue, which involves
Bone resorption
Bone deposition
Removal of minerals and collagen fibers from bone by osteoclasts
Bone resorption
Addition of minerals and collagen fibers to bone by osteoblasts
Bone deposition
What is the renewal rate for spongy bone tissue
5 times the rate for compact bone
Growing bone requires large amounts of
Calcium and phosphorus
Collagen synthesis depends on vitamins
B12, C, and K
“B12ACK”
Vitamin A does what
Stimulates osteoblasts
Promotes intestinal absorption of calcium
Calcitriol (Vitamin D)
What does the parathyroid hormone do
- Promotes resorption of bone matrix
- Prevents loss of calcium in the urine
- Promotes vitamin D (calcitriol) formation
Produced by parafollicular cells of the thyroid gland, lowers blood calcium levels by inhibiting bone resorption
Calcitonin
Thin layer of fibrous connective tissue
Sutures
More space than a suture; more fibrous connective tissue
Syndemoses
Teeth in sockets of upper and lower jaw
Gomphoses
What are cartilaginous joints
Joints components connected by cartilage
- Fibrocartilage or hyaline cartilage
- No synovial cavity
- Little or no movement
Types of cartilaginous joints
Synchondroses
- Hyaline cartilage connecting bones; ossify with age
Symphyses
- Fibrocartilage connecting bones (thin layer of hyaline) typically midline
Most moveable joint
Synovial joints
Parts of synovial joints
- Articular capsule
- Synovial membrane
- Synovial fluid
- Articular cartilage
Dense irregular and regular connected tissue in the synovial joint
Articular capsule
Lines the capsule; secretes synovial fluid of synovial joints
Synovial membrane
Viscous, clear fluid; lubericates, allows diffusion of nutrient and wastes of synovial joints
Synovial fluid
Covers epiphyses of bones; not covered by synovial membrane in synovial joints
Articular cartilage
What is the most abundant type of cartilage in the body?
Hyaline cartilage
Where is Hyaline cartilage found?
- Nasal septum
- Larynx
- Tracheal rings
- Most articulation surfaces
- Sternal ends of ribs
Most cartilage is covered by?
Dense, irregular connective tissue call perichondrium
After becoming vascularized, the perichondrium?
Becomes periosteum
What helps put things into cartilage?
Force of compression
Cartilage has?
No blood vessels (except in perichondrium) and no nerves
What are the types of cartilage?
Hyaline cartilage
Fibrocartilage
Elastic cartilage
What are the functions of the bone tissue?
- Support of soft tissues
- Protection of internal organs
- Assistance in movement
- Mineral Homeostasis (storage of calcium and phosphorous)
- Blood cell production
- Triglyceride storage
Where is the site of blood cell formation?
Red bone marrow
Yellow bone marrow is
Adipose connective tissue
Shaft or body of the long bone
Diaphysis
Distal and promise ends of long bone
Epiphyses
Where the diaphysis and epiphyses meet
Metaphyses
At the metahysis of a growing bone
Epiphyseal plate
Hyaline cartilage covering the epiphyses
Articulate cartilage
Dense irregular connective tissue that covers the bone (except for the articulate cartilage)
Periosteum
Space inside the diaphysis
Marrow cavity
Membrane lining the marrow cavity
Endosteum
How is the periosteum attached to the underlying bone?
Perforating fibers (AKA sharpey’s fibers)
What are perforating fibers?
Thick bundles of collagen fibers that extend from the periosteum into bone matrix
Osteogenic cells are derived from?
Mesenchyme
Large cells formed by fusion of numerous monocytes
Osteoclasts
Non-mitotic cells that synthesize and secrete collagen fibers
Osteoblasts
Non-mitotic cells having processes interconnected by gap junctions
Osteocytes
What are the tree rings of bone matrix around the Haversian canals?
Concentric lamellae
What do the Haversian’s (central) canals do?
- Intersect Volkman’s canals
- Run longitudinally
- Carry vessels and nerves
Cavities between lamellae; each contains one osteocytes
Lacunae
Tiny canals that project from the lacunae; contain ECF and projections of osteocytes; osteocytes connect via gap junctions
Canaliculi
Fill spaces between Haversian Systems; fragments of old systems that have been remodeled
Interstitial lamellae
Encircle the marrow cavity just superficial to the endosteum
Inner circumferential lamellae
Convey vessels and nerves from the periosteum to the Haversian systems
Volkman’s canals (AKA perforating canals)
Red marrow is the site of what in adults?
Hemopoiesis
Where does spongy bone tissue receive nutrients?
Marrow cavity
Nutrient artery enters the diaphysis via
Nutrient foramen and associated nutrient groove
Separate arteries supply metaphysis and epiphysis
The periosteum is rich in what?
Sensory nerves, especially those that are sensible to tearing or tension
What bones form in intramembranous ossification?
Clavicle
Bones of skull
Mandible
What happens during intramembranous ossification?
- Fibrous CT membrane forms where the future bone will be
- Center of ossification forms
- mesenchymal stem cells differentiate into osteogenic cells, then into osteoblasts
- osteoblasts secrete matrix until surrounded
What is the most common way bones form?
Endochondral ossification
What happens during endochondral ossification?
Development of hyaline cartilage model
- mesenchymal stem cells differentiate into condroblasts that secrete cartilage matrix, producing a cartilage model
Perichondrium develops around cartilage model
Fibrous connective tissue membrane on the outer surface of cartilage, containing condroblasts and in the case of cartilage model, osteogenic cells
Perichondrium
Where does bone length growth occur?
Epiphyseal plate
Bone thickness growth
- Occurs in the periosteum
- Osteoblasts deposit bone matrix along sides of a periosteum artery, forming ridges
- Osteoblasts become osteocytes when they are surrounded by matrix
- Ridges fuse, surrounding periosteum artery forming new Haversian system
- Osteocytes in endosteum form new concentric lamellae
Effects of bone remodeling
- Removes injured bone and replaces it with new bone tissue
- Strengthens bone tissue to meet load
- Altering bone shape for better suppliers
- More resistant to fracture
- Supports calcium homeostasis
What happens in a fracture hematoma?
- Blood vessels at site of fracture rupture; bleed and clot forms (6-8 hours after injury)
- Bone cells die due to loss of blood supply
- Capillaries grow to hematoma and phagocytic cells migrate remove debris
- Osteoclasts digest the dead and damaged bone for several weeks
Fibrocartilage callus formation
- Capillaries invade the hematoma transform into procallus
- Fibroblasts migrate in and secrete collagen
- Osteogenic cells differentiate into condroblasts that secrete cartilage matrix
- Procallus is transformed into fibrocartilage that bridges fracture
(Takes about 3 weeks)
Bony callus formation
- osteogenic cells in fibrocartilaginous callus differentiate into osteoblasts
- osteoblasts start to form trabeculae converting the callus into spongy bone
(Lasts 3-4 month; cast off)
Bone remodeling
- Dead fragments of bone are digested by osteoclasts
- Spongy bone on periphery is remodeled into compact bone
What are the steps to bone fracture and repair?
- Fracture hematoma
- Fibrocartilaginous callus formation
- Bony callus formation
- Bone remodeling
Calcium reservoir is what?
Bone stores 99% of body’s calcium to help regulate the calcium in the blood
What is calcium important for?
- Synaptic transmission
- Muscle contraction
- Blood clotting