Skeletal Flashcards by Cal Schiller

Functions of Cartilage

Comprises parts of the skeleton where flexibility is required

Articular surfaces (smooth/low friction)

Template for bone formation

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Consists of a dense network of collagen fibers and elastic fibers embedded in a jelly-like ground substance of chondroitin sulfate

Cartilage

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Capable of enduring more stress than either loose or dense connective tissue

Cartilage

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Strength is due to collagen fibers

Resilience (plasticity) is due to chondroitin sulfate

cartilage

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Cells of mature cartilage are ____, which are derived from ____

chondrocytes

chondroblasts

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Chondrocytes reside in ____

lacunae

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Most cartilage is covered by a dense, irregular connective tissue called ___

perichondrium

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Cartilage has no blood vessels, and, except in the ____, has no nerves. It is relatively inactive, grows slowly, and heals poorly due to the lack of intrinsic blood supply and confinement of chondrocytes to lacunae

perichondrium

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Types of cartilage

Hyaline
Fibrocartilage
Elastic

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____ cartilage is the most abundant type of cartilage; it covers the ends of long bones and parts of the ribs, nose, trachea, bronchi, and larynx.

Hyaline

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Hyaline covers

ends of long bones
parts of the ribs
nose
trachea
bronchi
larynx

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_____, with its thick bundles of collagen fibers, is a very strong, tough cartilage

Fibrocartilage

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_____ typically occurs as a disc-shaped segement of cartilage between bones

Fibrocartilage

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____ cartilage consists of chondrocytes located in a threadlike network of elastic fibers

Elastic

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____ makes up the malleable part of the external ear and th epiglottis

Elastic

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Bone stores ____ and _____ (minerals)

calcium

phosphorus

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Yellow bone marrow is adipose connective tissue and stores _____

triglyceride

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Shaft/bone

bone

Diaphysis

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Distal/proximal ends

bone

Epiphyses

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Where the diaphysis and epiphyses meet

bone

metaphyses

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At the metaphysis of a growing bone

epiphyseal plate

“growth” plate

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Articular cartilage is ____ cartilage covering the epiphyses

hyaline

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dense irregular connective tissue that covers the bone (except for the articular cartilage)

Periosteum

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Membrane lining the marrow cavity

Endosteum

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Space inside the diaphysis

marrow cavity

Bone Matrix components

Water - 1/4 Collagen - 1/4 Hydroxyapatite (CALCIUM)- 1/2

stem cells that can divide and differentiate into osteoblasts

Osteogenic cells | from mesenchyme

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 | not in the same cell lineage

Histology order of bone

mesenchyme Osteogenic cells osteoblast osteocytes

AKA cortical bone

compact

AKA cancellous bone, trabecular bone

spongy

Most of skeleton is ___

compact

Compact Bone contains units called ____ or Haversian systems formed from concentric lamellae (rings of calcified matrix)

osteons

between osteons are left over fragments of older osteons

Interstitial lamellae

encircle the bone beneath the periosteum

Outer circumferential lamellae

encircle the medullary cavity

inner circumferential lamellae

small spaces between the lamellae which house osteocytes

Lacunae

small channels filled with extracellular fluid connecting the lacunae

canaliculi

Blood and lymphatic vessels are found in the osteon

central canal

allow transit of these vessels to the outer cortex of the bone

perforating (volkmann's) canal

Spongy bone lacks osteons. Instead, lamellae are arranged in a lattice of thin columns called

trabeculae

Trabeculae of spongy bone support and protect the red bone marrow and are oriented along lines of _____ (helps bones resist stresses without breaking)

stress

(blood cell production) occurs in spongy bone

Hematopoiesis

As in compact bone, lacunae contain osteocytes that nourish the mature bone tissue from the blood circulating through the ___

trabeculae

The interior of long bones is made up primarily of ___. The use of spongy bone lessens overall bone weight

spongy bone

____ or osteogenesis is the process of forming new bone

ossification

Bone formation occurs in 4 situations:

formation of bone in an embryo growth of bones until adulthood remodeling of bone repair of fractures

Osteogenesis occurs by two different methods

Intra-membranous ossification Endochondral ossification

the simpler of the two methods

Intra-membranous ossification

It is used in forming the flat bones of the skull, mandible, and clavicle Bone forms from mesenchymal cells that develop within a membrane – without going through a cartilage stage (recall that mesenchyme is the tissue from which almost all other C.T. develop.) MANY OSSIFICATION CENTERS

Intra-membranous ossification

produces spongy bone

Intra-membranous ossification (no cartilage stage)

is a process whereby cartilage is replaced by bone

Endochondral ossification compact and spongy bone

the method used in the formation of most bones, especially long bones

Endochondral ossification

There are one primary and two secondary centers of growth

Endochondral ossification

Look at slides 28-33 for endochondral ossification process

word

removal of minerals and collagen fibers from bone by osteoclasts

bone resorption

addition of minerals and collagen fibers to bone by osteoblasts

bone deposition

If too much new tissue is formed, the bones become abnormally thick and heavy (acromegaly)

(acromegaly)

They may also become too “soft”, as seen in the bone diseases rickets and ___

osteomalacia

Excessive loss of calcium weakens the bones, as occurs

osteoporosis

new bone is more resistant to fracture than is old bone

word

First step in bone repair

Formation of a fx hematoma (as a result of blood vessels breaking in periosteum and osteon)

Second/third steps in bone repair

Formation of callus (a few weeks) Phagocytes removes cellular debris Fibroblasts deposit collagen to form a fibrocartilaginous callus which is followed by osteoblasts forming a bony callus of spongy bone

Final step of bone repair

("remodeling" several months) spongy bone replaced by compact bone.

stimulates activity of osteoblasts

vitamin A

needed for synthesis of collagen

Vitamin C

essential to healthy bones because it promotes the absorption of calcium from foods in the gastrointestinal tract into the blood

Vitamin D

needed for synthesis of bone proteins

Vitamins K and B12

required for many important activities; for example, synaptic transmission, muscle contraction, and blood clotting

Calcium

Promotes resorption of bone matrix Prevents loss of calcium in the urine Promotes vitamin D (calcitriol) formation

Parathyroid hormone

promotes intestinal absorption of calcium

Calcitriol (vitamin D)

produced by parafollicular cells of the thyroid gland, lowers blood calcium levels by inhibiting bone resorption

calcitonin

Slide 45 for calcium feedback loop

word

point of contact between two bones, between bone and cartilage, or between bone and a tooth

Joints

thin layer of fibrous connective tissue

sutures | Fibrous joint

more space than a suture; more fibrous connective tissue

Syndesmoses | Fibrous joint

teeth in sockets of upper and lower jaw

Gomphoses | Fibrous joint

Bones attached by fibrous connective tissue with little movement

Fibrous joint | NOT fibrocartilage

Interosseous membrane

syndesmoses

Joint components connected by cartilage -Fibrocartilage or hyaline cartilage -No synovial cavity Little or no movement

cartilaginous joint

AKA primary cartilaginous joints: hyaline cartilage connecting bones; cartilage may ossify with age

synchondrases epiphyseal plate

AKA secondary cartilaginous joints: fibrocartilage connecting bones

Symphyses | pubic symphysis, intervertebral discs, manubriosternal joint

Most movable with articular capsule (dense irregular/regular) and synovial membrane, which lines the capsule and secretes synovial fluid

synovial joint

viscous, clear fluid; lubricates, allows diffusion of nutrient and wastes

Synovial fluid

covers epiphyses of bone; not covered by synovial membrane

Articular cartilage

Synovial joints MAY contain articular discs

aka menisci

Adult rickets

osteomalacia

disease (in children) growing bone becomes soft and easily deforms. Bone fails to ossify at epiphyseal plate reuslting in bowed lgs,deformities of skuill, ribs, pelvies

rickets

occurs when new bone fails to clacify during remodeling

osteomalacia