Lecture1 Flashcards
Four Types of Tissue
epithelial (skin), connective (bone and cartilage), muscle, nervous
Skeletal Function
support, protection, movement, hemopoiesis, mineral resevoir
How does bone act as an endocrine organ?
releases minerals (calcium, magnesium, phospohrus)
Reasons for Bone Remodeling
reaction to stress (negative and positive), age
Number of Bones in Adult vs. Child
born = 270, adult = 206 (bones fuse during maturation)
Types of Joints
fibrous, cartilaginous, synovial
Fibrous Joint
held together by fibrous tissue, no synovial cavity, no motion, ex. Bones of skull
Cartilaginous Joint
no synovial cavity, held together by cartilage, slight movement, ex. Intervertebral joints, ribs
Synovial Joint
synovial cavity and articular cartilage, secretes fluid, free movement within allowable limits based on the shape of the joint, ex. Shoulder, knee
Gliding Joint
one bone slides over another, gliding motion, ex. Sternum, clavicle, carpal, tarsal
Hinge Joint
spool-shaped process in a concave socket, flexion/extension, ex. Fingers, elbow, knee
Pivot Joint
arched process fitting around a peg-like process, rotation, ex. Atlas/axis
Condyloid Joint
oval condyle of one bone fitted into an elliptical cavity of another bone, motion in two planes at right angles, ex. Radiocarpal joints
Saddle Joint
one bone saddle shaped the other like a rider (yeehaw!), flexion/extension and abduction/adduction, ex. Carpometacarpal joints of thumb, SC, ankle
Ball and Socket Joint
ball-like surface of one bone fitted into cup-like surface of other, rotation, widest ROM, ex. Shoulder, hip
Cartilage
connective tissue composed of chondrocyte cells in an extracellular matrix aka ground substance
Ground Substance
chondroitin sulfate with collagen (water, spongy properties, shock absorption), and elastin
Types of Cartilage
hyaline, fibrocartilage, elastic
Hyaline Cartilage
relatively few collagen fibers, found at articular surfaces, tips of ribs, trachea (most long bones begin as hyaline cartilage model then convert over time into bone)
Fibrocartilage
contains many collagen fibers embedded in matrix, resists tensile forces well so difficult to injure, found in intervertebral discs, pubis symphysis, menisci of knee joint
Elastic Cartilage
contains many elastic fibers (few collagen), springy cartilage, found in external pinna of ear, epiglottis (tissue has memory)
Characteristics of Cartilage
avascular and anueral, blood vessels only extend to perichondrium, requires nutrients/oxygen that must diffuse through the matrix to the chondrocytes (water and movement assist diffusion)
Unit of Bone in Many Vertebrates
osteon or Haversian system
Bone Characteristics
much harder connective tissue than cartilage, direct vascular and nerve supply, extracellular matrix composed of calcium phosphate and other organic salts
Osteon (Haversian System)
concentric rings of osteocytes interconnected with blood vessels inside, gives bone its rigidity and resistance to pressure
Volkmann’s Canals
osteons are interconnected by this series of canals
How many pounds of thrust needed to break a human femur?
25,000..anyone want to test that?
Types of Bone Cells
osteoblasts, osteoclasts, osteocytes
Osteoblasts
immature bone cells secrete new bone, lay down new bone then become osteocyte
Osteocytes
maintain equilibrium in mature bone (mineral balance)
Osteoclasts
remove existing bone so that calcium can go into blood supply when needed, big boys, multinucleated
Bone Classification
based on appearance (compact vs. spongy/cancellous), based on position (cortical/outside vs. medullary/inside), based on method of formation (endochondral/cartilage model vs. intramembranous)
Endochondral Bone Development
three basic regions (diaphysis-shaft Sierra, epiphysis-ends, metaphysis-intermediate where growth occurs)
Endochondral Bone Growth
epiphyseal line - growth plate between epiphysis and metaphysis that closes at the end of puberty, logitudinal (length) and episitional (girth) growth
Steps in Endochondral Bone Development
- formation of hyaline cartilage model 2. formation of the periosteal bone collar (chondrocytes–>osteoblasts) 3. invasion of blood vessels at midpoint of diaphysis 4. ossification spreads to the ends, invasion of blood vessels at ends 5. secondary centers of ossification form in the epiphysis 6. growth stops when ossification fronts close the epiphyseal plates (18 for female, 20/21 for male)
Ossification and Growth Zones
zone of hyaline cartilage–>zone of proliferation–>zone of hypertrophy–>zone of calcification–>zone of ossification
Zone of Hyaline Cartilage
resting zone, no mitosis
Zone of Proliferation
chondrocytes become stimulated and go through mitosis, daughter cells line up in columns
Zone of Hypertrophy
do you even lift bro?
Zone of Calcification
cells secrete calcium into matrix
Zone of Ossification
calcium dense enough to have created bone, chondrocytes now are osteoblasts (on outside of bone matrix, if on the inside it is an osteocyte), osteoclasts are multinucleated and are breaking down bone
Lacunae
lines of cells in process of proliferation, little lakes
Intramembranous Bone Formation
all irregular bones (skull), osteoblasts appear in condensations of mesenchyme (immature mesoderm) without a cartilage precursor, bone spicules form
Germ Layers in Development
ectoderm (nerves and skin), mesoderm (bones and muscle), endoderm (visceral organs)
Canaliculi
one cell processes reaching out to another, canals connecting osteocytes
Axial Skeleton
protection for nervous system, stability, 80 bones
Appendicular Skeleton
extremities, mobility, 126 bones