A&P Chap 6-7 Flashcards
What is skeletal cartilage made of?
Made of highly resilient, molded cartilage tissue that consists primarily of water; contains no blood vessels or nerves
What is perichondrium and its characteristics?
Layer of dense irregular connective tissue surrounding cartilage like a girdle
- Helps cartilage resist outward expansion when compressed
- Contains blood vessels to nourish the cartilage cells
What is the thickness of cartilage limited by?
The distance nutrients can diffuse through the matrix to reach the cells
What are the three types of cartilage?
- Hyaline
- Elastic
- Fibrocartilage
All three have chondrocyte cells, enclosed in lacunae within the extracellular matrix containing jellylike ground substance and fibers.
What are the characteristics of hyaline cartilage?
- Provides support, flexibility, and resilience
- Most abundant type; contains collagen fibers only
- Articular (joints), costal (ribs), respiratory (larynx), nasal cartilage (nose tip)
What are the four types of hyaline cartilage types?
- Articular (joints): cover the ends of most bones at movable joints
- Costal (ribs): connect the ribs to the sternum
- Respiratory (larynx): larynx and reinforce respiratory passages
- Nasal (nose tip): support the external nose
What are the characteristics of elastic cartilage?
- Similar to hyaline cartilage, but containing more elastic fibers
- External ear and epiglottis
What are the characteristics of fibrocartilage?
- Highly compressible
- Great tensile strength
- Roughly parallel rows of chondrocytes alternating with thick collagen fibers
- Menisci of the knee; vertebral discs
What are the two ways cartilage grows?
- Appositional
- Interstitial
What is the appositional growth of cartilage?
Cartilage-forming cells in perichondrium secrete new matrix against external face of existing cartilage
What is the interstitial growth of cartilage?
- Chondrocytes within lacunae divide and secrete new matrix, expanding cartilage from within
- Growth ends during adolescence when skeleton stops growing
What are the seven important functions of bones?
- Support; for body and soft organs
- Protection; protect brain, spinal cord, and vital organs
- Anchorage; levers for muscle action
- Mineral and growth factor storage; calcium and phosphorus, and growth factors reservoir
- Blood cell formation; hematopoiesis occurs in red marrow cavities of certain bones
- Triglyceride storage; fat, used for an energy source, is stored as yellow marrow in cavities of long bones.
- Hormone production; osteocalcin secreted by bones: regulates insulin secretion, glucose levels, and metabolism
Cartilage is surrounded by ____________.
Bone is surrounded by ____________.
Cartilage - perichondrium
Bone - periosteum
In cartilage, _______ is in lacunae.
In bone, ________ is in lacunae.
Cartilage - chondrocytes
Bone - osteocytes
In cartilage, _______ is in lacunae.
In bone, ________ is in lacunae.
Cartilage - chondrocytes
Bone - osteocytes
In cartilage, extracellular matrix is __________.
In bone, extracellular matrix is ________.
Cartilage - flexible
Bone - rigid (due to inorganic calcium salts)
In cartilage, extracellular matrix is made by ___________.
In bone, extracellular matrix is made by ___________.
Cartilage - chondroblasts
Bone - osteoblasts
Name the type(s) of growth cartilage and bone go through.
Cartilage - appositional and interstitial.
Bone- appositional only
What are two groups of skeletons based on location?
Axial skeleton
- Long axis of body
- Skull, vertebral column, rib cage
Appendicular skeleton
- Bones of upper and lower limbs
- Girdles attaching limbs to axial skeleton
Why are bones considered organs?
Because they contain different types of tissues
Bone (osseous) tissue predominates, but a bone also has nervous tissue, cartilage, fibrous connective tissue, muscle cells, and epithelial cells in its blood vessels
What are spongy bone also called?
Trabeculae
What are examples of long bones?
- Arms: humerus, ulna, radius
- Legs: femur, tibia, fibula
- Fingers: metacarpals, phalanges
- Toes: metatarsals, phalanges
What are examples and functional characteristics of short bones?
- Wrist and ankle
- Sesamoid bones: act to alter the direction of pull of a tendon.
- Reduce friction and modify pressure on tendons to reduce abrasion or tearing.
What are examples of flat bones?
- Thin, flattened, bit curved
- Sternum
- Scapulae
- Ribs
- Cranial bones of the skull
What are examples of irregular bones?
- Vertebrae
- hip bones
What is diaphysis
- Shaft of long bone
- Central medullary cavity (marrow cavity) contains no bone tissue, contains yellow marrow in adults
- Thin layer of spongy bone between marrow and the compact bone
What is epiphyses
- Bone ends
- Thin layer of articular (hyaline) cartilage covers the joint surface of each epiphysis
Where are periosteum and endosteum found?
- Periosteum: covers outside of compact bone
- Endosteum: covers inside portion of compact bone
What is periosteum
- Richly supplied with nerve fibers and blood vessels
- Provides anchoring points for tendons and ligaments
What is endosteum
A membrane that lines the center of bones that contain bone marrow
What is a hematopoietic tissue and how the locations differ between infants and adults?
Red marrow
Infants: the medullary cavity and all spongy bone contain red marrow.
Adults: Red marrow esp. in long bones have been replaced by yellow marrow, extends to epiphysis. Red marrows only found in the cavities b/w trabeculae of spongy bones in: flat bones of skull, sternum, ribs, clavicles, scapulae, hip bones and vertebrae, the heads of femur and humerus.
What are osteoprogenitor cells (osteogenic cells)
Mitotically active stem cells found in the periosteum and endosteum
- Flattened or squamous
- When stimulated, some become osteoblast
What are osteoblasts?
- Actively mitotic bone forming cells
- Secrete the bone matrix: collagen and calcium binding proteins
- Play a role in matrix calcification
- Becomes osteocytes when completely surrounded by the matrix
What are osteocytes?
- Monitor and maintain the bone matrix
- Act as stress sensors and respond to mechanical stimuli e.g. bone loading, deformation, weightlessness
- Communicate with osteoblasts and osteoblasts in matrix formation
- Can trigger bone remodeling to maintain calcium homeostasis
What is a chondrocyte?
- Maintain the extracellular matrix (ECM) and produce the cartilage matrix
- Surrounded by collagenous fibers, release substances to make cartilage strong yet flexible
- Found within intervertebral discs and in any form of articular cartilage
Where is bone lining cells found?
On bone surfaces where bone remodeling is not going on. Help maintain the matrix.
What is osteon?
- The structural unit of compact bone.
- Enlongated cylinder parallel to the long axis of the bone.
- Tiny weight-bearing pillars
- Like growth rings of a tree trunk
- Each matrix tube is a lamella; the collagen fibers run in alternating patterns to withstand torsional stresses
What occupies lacunae at the junctions of the lamellae?
Osteocytes
What are canaliculi?
- Hairlike canals radiating from the lacunae
- Filled with tissue fluid and contains the osteocyte extensions
- Tie all the osteocytes in a mature osteon together, allowing them to communicate and permitting nutrients and wastes to be relayed from one osteocyte to the next
- Allow bone cells to be well nourished.
What is interstitial lamellae?
Incomplete lamellae. Either fill the gaps b/w forming osteons or are remnants of osteons that have been cut through by bone remodeling
What is circumferential lamellae?
- Located deep to the periosteum, and superficial to the endosteum.
- Extend around the entire circumference of the diaphysis
- Effectively resist twisting of the long bone
What is osteoid?
- An organic part of the matrix of the bone.
- Makes up one third of the matrix, and includes ground substance and fibers, secreted by osteoblasts.
- Contribute to a bone’s structure and flexibility and tensile strength that allow stretching and twisting.
Bone’s resilience is thought to come from ______________ in or b/w collagen molecules.
sacrificial bonds
What are examples of inorganic compounds in bone?
- hydroxyapatites
- mineral salts; calcium phosphates
What are ossification and osteogenesis?
The process of bone tissue formation.
Ossification in adults serves mainly for bone remodeling and repair.
What happens to bone growth before week 8?
Embryonic skeleton consists only of fibrous connective tissue membranes and hyaline cartilage
- The benefit is that it can accommodate mitosis
What is endochondral bone?
Bone developed through replacing hyaline cartilage
What is membranous bone?
Bone developed from a fibrous membrane
What is endochondral ossification?
- Begins late in the second month of development
- More complex than intramembranous ossification
- Hyaline cartilage is broken down
What is primary ossification center?
The first area of a bone to start ossifying. Occur in the diaphysis and in irregular bones usually in the body of the bone
What is secondary ossification centers?
Develop in one or both epiphyses. Spongey bone is retained and no medullary cavity forms.
Hyaline cartilage remains only: 1. on the epiphyseal surfaces, as articular cartilage. 2. At the junction of the diaphysis and epiphysis, as epiphyseal plates
What is intramembranous ossification?
Forms the cranial bones of the skull (frontal, parietal, occipital, and temporal bones) and the clavicles.
Mostly flat bones
- At about week 8 of development
- Begins within fibrous connective tissue membranes formed by mesenchymal cells.
What does osteoclast do?
- Aka bone resorption cells
- Giant multinucleate cells
- Degrade bone to initiate normal bone remodeling and mediate bone loss.
Bone remodeling involves both __________ and ____________.
New bone formation and bone resorption
What is bone resorption?
Involves the removal of hard bone tissue by osteoclasts followed by the laying down of new bone cells by osteoblasts.
What is epiphyseal plate closure?
The epiphyseal plates become thinner until they are entirely replaced by bone tissue. Longitudinal bone growth ends when epiphysis and diaphysis fuse. Happens around 18 for female and 21 for males, promoted by growth hormone (testosterone and estrogen)
What stimulates epiphyseal plate activity in infancy and childhood?
Growth hormone released by the anterior pituitary gland. Thyroid hormones modulate the activity of growth hormones, ensuring proper skeletal proportions
What does PTH parathyroid hormone do?
- Produced by parathyroid glands.
- Released when blood levels of calcium ion decline.
- Stimulates osteoclasts to resort bone, releasing calcium ions into the blood.
What determines where bone remodeling occurs?
Mechanical stress
Functions of the facial bones.
- Form the framework of the face
- Contain cavities for the special sense organs of sight, taste and smell
- Provide opening for air and food passage
- Secure teeth
- Anchor facial muscles of expressions
The major skull sutures are:
- coronal: parietal bones meet the frontal bone anteriorly
- lambdoid: parietal bones meet the occipital bone posteriorly
- sagittal: parietal bones meet superiorly at the cranial midline
- squamous: parietal and temporal bone meet on the lateral aspect of the skill
Sphenoid bone is the keystone bone of the cranium because…
it is in contact with all of the other cranial bones.
Ethmoid bone:
contributes to the formation of the orbit, nasal cavity, nasal septum and the floor of the anterior cranial fossa.
Where is sella turcica found and what does it do?
The sphenoid bone has a superior depression called the sella turcica. Surrounds and protects your pituitary gland.
Characteristics of hyoid bone
- Not a bone of skull
- Lies in anterior neck inferior to mandible
- Only bone in the body that does not articulate directly with another bone
- Anchored by ligaments.
What are paranasal sinuses formed from?
From five skull bones:
- Frontal
- Sphenoid
- Ethmoid
- Paired maxillary bones
How many irregular bones are in the vertebral column?
26
How many regions are in the vertebral column?
Five
- Cervical (7) concave
- Thoracic (12) convex
- Lumbar (5) concave
- Sacral (5) convex
- Coccyx (4)
Name the major supporting ligaments of the vertebral column
Anterior and posterior longitudinal ligaments
- Support and prevent hyperextension or hyperflexion bending
What is the function of the ligamentum flavum?
- Maintain upright posture
- Helps to preserve the normal curvature of the spine
- Straighten the column after it has been flexed
What is intervertebral discs
Cushionlike pad sandwiched b/w vertebrae that act as shock absorbers
- Nucleus pulposus and anulus fibrosus
What is perichondrium and its characteristics?
Layer of dense irregular connective tissue surrounding cartilage like a girdle
- Helps cartilage resist outward expansion when compressed
- Contains blood vessels to nourish the cartilage cells
