Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
71 Cards in this Set
- Front
- Back
|
Identify and describe the two mechanisms of cartilage growth.
|
Interstitial growth - mitosis and then secrete matrix, which pushes the cells apart
Appositional growth - perichondrium differentiates into chondrocytes at surface, which produce matrix; happens 2nd? |
|
|
What bones make up the axial skeleton?
|
Skull
Vertebrae Rib cage |
|
|
How many bones are included in the axial skeleton?
|
80 bones
|
|
|
What bones make up the appendicular skeleton?
|
Upper and lower limbs
Pelvic and shoulder girdle |
|
|
How many bones are included in the appendicular skeleton?
|
126 bones
- 64 superior portion - 62 inferior portion |
|
|
Identify and describe the four types of cells that form and maintain bone tissue.
|
Osteogenic cells - from mesenchym, stem/mitosis, inner layer of periosteum + endosteum
Osteoblasts - form matrix/colagen fibers, initiate calcification Osteocytes - mature bone cells, have gap jctns for communication, maintain matrix Osteoclasts - unrelated 2 other 3, bone resorption, hemopoesis in marrow, many nuclei from fusion of 50 cells, ruffled border, secretes lysosomes |
|
|
Name the organic portion of bone matrix.
|
Oteoid - secreted by osteoblasts
|
|
|
What materials make up the organic and inorganic parts of the bone matrix?
|
Organic - osteoid - ground substance and collagen fibers; resistance to mech. stresses
Inorganic - hydroxyapatite - mineral salts, hydroxyapatitie crystals, calcium phosphate; resist compression forces |
|
|
Is the organic or inorganic part of the bone matrix primarily responsible for the tensile strength/stretching forces b/w ends of bone?
|
Organic - the osteoid; b/c of collagen fibers
|
|
|
Is the organic or inorganic part of the bone matrix primarily responsible for the compression strengh of bone?
|
Inorganic - mineral salts: hydroxyapatite, calcium phosphate packed in tightly
|
|
|
Which of the parts of the bone matrix makes the bone hard and heavy?
|
Inorganic portion - the packed crystals, mostly calcium phosphate
|
|
|
What are the primary minerals stored in bones?
|
Primary: Calcium, phosphorous
|
|
|
Name, describe and give an example of each of the five categories of bone, classified by shape.
|
Long - elongated; all limbs, excepte patella, carpals and tarsals
Short - rounded, cube-like, spongy bone; sesamoid bones develop in a tendon Flat - 2 parallel surfaces of compact, enclosing spongy; cranium, mandible, illium etc Irregular - don't fit the others; wormian/sutural bones, vertebrae, sphenoid, ethmoid |
|
|
What is the general function of spongy bone? Of compact bone?
|
Spongy - filled with red/yellow marrow; shock absorber, lightens bone
Compact - strength and hardness |
|
|
Describe the general structure of a long bone.
|
Diaphysis - medullary cavity, thin layer of spongy bone around cavity, compact bone thickest in middle
Epiphysis - rounded/bulbshaped, shock absorption Articular cartilage - hyaline, covers articular surfaces Metaphysis/epiphyseal lines - in kids who are still growing, hyaline cartilage (epiphyseal plate) Endosteum - delicate, vascularized, around medullary Periosteum Sharpey's fibers |
|
|
Describe the medullary cavity (where is it located, what structures are found there)?
|
Hollow cylindar
Thickest in middle of shaft Red and yellow marrow Surrounded by spongy bone layer and endosteum |
|
|
Describe the structure and function(s) of the periosteum.
|
Double layered membrane, everywhere, but articulating surfaces
Outer layer - dense irregular ct/fibrous layer Inner layer - osteoblasts and osteoclasts/ bone growth Vascularized |
|
|
What is the function of Sharpey's fibers?
|
Collagen fibers from periosteum into bone matrix
Anchor fibers of ligaments and tendons into bone Distribute mechanical forces over greater bone surface |
|
|
What is the function of the nutrient foramen?
|
Blood vessels penetrate periosteum and pass through foramen into bone; perforating/volkmann's canals pass through, to the central canal (?)
|
|
|
What are the differences between red and yellow marrow?
|
Red - hemopoeisis, exists in younger kids
Yellow - adipose tissue, replaces most, but not all red marrow later on in life |
|
|
What type of bone makes up the epiphyses?
|
Compact bone externally
Spongy bone internally Shock absorption |
|
|
What is the function of the epiphyses?
|
Shock absorption
|
|
|
What is teh function of the articular cartilage
|
- Thin layer of hyaline covering articular surfaces
- Shock absorption and reducing friction |
|
|
What type of bone makes up the diaphysis?
|
Thin layer of spongy bone surrounding medullary cavity
Thick layer of compact bone |
|
|
Describe the microscopic structure of compact bone, paying attention to the location of the lamellae, lacunae, osteocytes and canaliculi.
|
Osteons organized around central canal; perforating/volkmann's canals connect blood supply of periosteum, central canal and marrow
Lamellae - opposite concentric layers of matrix; lacunae sandwitched b/w Canaliculi connect lacunae and connect them to central canal |
|
|
Describe the location and function of the perforating (or Volkmann's) canals.
|
- Connect blood of periosteum, central canal and bone marrow
- through compact bone at right angles to central canal Lined with endosteum |
|
|
Describe the location and function of the central (or haversian) canals.
|
Osteons organized around central canal
Carries blood vessels, lymph, nerve, etc |
|
|
Describe the general structure of short, flat and irregular bones.
|
- Thin plates of compact bone covered wiith periosteum
- Inside: Spongy bone covered with endosteum (called diploe in flat bones) Good shock absorbers Marrow is important for rbc's since most disappears on long bones |
|
|
How do the trabeculae of spongy bone respond to changes in the patterns of stress to which the bone is exposed?
|
They orient in the direction of the greatest stress
|
|
|
In what part of bone does blood cell production occur?
|
In the red marrow of the spongy layer
|
|
|
Which bones are sites of rbc production in children? In adults?
|
Children - most bones, including long bones
Adult - long bone red marrow is now yellow; rbc production occurs primarily in short, flat and irregular bones; sternum, ribs, os coxa etc. |
|
|
Compare and contrast the mocroscopic structure of compact and spongy bone.
|
Spongy - no osteons; covered with endosteum; trabeculae; lamellae in irregular arrangments, only a few layers thick
Compact - regular concentric lamellae organization, thick |
|
|
What tissues make up the embryonic skeleton before the 6th week of development?
|
Fibrous CT and hyaline cartilage
Template = 2 membranes + hyaline cartilage Then bone tissue begins to form |
|
|
Describe the process of intramembranous ossification.
|
- Skull bones
- ossification centers made as mesenchymal cells cluster/differ.; in fibrous CT membrane Osteoid secreted - alkaline phosphotase attracts Ca phosphate salts to deposit Woven bone and periosteum form; random ca salt deposits Periostium dev. and woven bone replaced w/lamellar bone, red marrow trapped |
|
|
Describe the process of endochondral ossification.
|
- Bones below the skull
- cartilage model/bone template; mesenchymal cells diff into chondroblasts, which make Hyaline cart. Cartilage model grows - interstitial and apositional; chondrodytes burst = alkaline pH = calcification Primary ossification center forms; bone collar forms around diaphysis; cartilate discintegrating Periosteal bud invades cartilage model Secondary ossification center at epiphysis which forms no marrow Articular cartilage and epiphyseal plates formed |
|
|
Compare and contrast intramembranous and endochondral ossification.
|
Intramembranous - skull bones, ossification occurs in fibrous CT membrane, mesenchymal cells diff. into osteoblasts
Endochondral - Bones below skull, cartilage model, mesenchymal cells diff into chondroblasts 1st, then others in perichondrium diff into osteoblasts, has ossification centers(primary and secondary) |
|
|
What cells secrete osteoid?
|
Osteoblasts in fibrous membrane during intramembranous ossification
- causes calcification to begin as Ca phosphate salts start depositing |
|
|
Where are the primary centers of ossification typically located?
|
Diaphysis - mesenchymal cells in perichondrium diff. into osteoblasts
|
|
|
Where are the secondary centers of ossification typically located?
|
At one or both epiphysis
|
|
|
Identify and describe the location of the hyaline cartilage structures that remain when secondary ossificatoin is complete?
|
-.Articular bone cartilage
- Epiphyseal plate, b/w epiphysis and diaphysis, which allows for growth to continue occuring in the bone |
|
|
How do long bones grow in length?
|
- Epiphyseal plate
- Side closest to epiphysis = chondrocyte mitosis, pushed away, rupture and die, initiating calcification b/c of increased pH, new bone tissue is formed closest to diaphysis |
|
|
What is the function of the epiphysial plate?
|
To allow bone growth, lengthwise
Chondrocyte death is what initiates calcification so that ossification can occur as well Provides fluid matrix so that growth can occur |
|
|
Describe the zones into which chondrocutes are organized within hte epiphyseal plate.
|
Quiescent - closest to epiphysis, cartilage anchors growth plate, resting
Proliferation - chondrocytes enlarged, mitosis Hypertrophy - chondrocytes rupture and die, increasing pH Calcification - spicules of calcified cartilage, occuring b/c of pH Osteogenesis - new bone tissue forming |
|
|
In which zone of the epiphyseal plate does ossification occur?
|
Osteogenic zone
|
|
|
Which zone of the epiphyseal plate exhibits a high rate of chondrocyte cell division?
|
Proliferation zone/ zone of proliferating cartilage
|
|
|
What is the significance of epiphyseal plate closure?
|
- No further bone lengthening possible
- Marked by epiphyseal line - mitosis of chondrocytes overtaken by ossification - Closes faster on females and on distal epiphysis |
|
|
Name and describe the process by which long bones grow in thickness/diameter.
|
- Appositional growth
- osteoblasts beneath periosteum form bone ridges around beriosteal blood vessel - Ridges surround vessel, form central canal of new osteon - Periosteum now endosteum, osteoblasts form new lamellae and grow inward - Simultaneous growth of medullary cavity |
|
|
What is/ are the function(s) of bone remodeling?
|
- Bone renewal and healing
- Calcium homeostasis - Realign matrix along mech. stress lines |
|
|
What complementary processes are involved in bone remodeling?
|
Bone deposit
Bone resorption |
|
|
Describe the structure of osteoclasts. What is the function of these cells?
|
- ruffled border adheres to bone tissue
- derived from hemopoesis in marrow - fusion of up to 50 monocyte like cells, so many nuclei - make and release lysosome; creates seal so enzymes only go on that part of the surface - breaks down bone |
|
|
How do osteoclasts break down bone matrix?
|
Make lysosomes
Attatch to bone with ruffled border and release lysosomes on that part of the bone Found in little depressoins on the inner surfaces of bone - endosteum |
|
|
Identify and describe the physiologic steps involved in the repair of bone fractures.
|
Hematoma/blood clot formation - 6-8 hrs after, blood from bone periostium, tissue
Fibrocartilaginous callus froms - firbroblasts secrete matrix, blood vessel growth stimulated. fibers across break, new chondroblasts make cart. Bony callus forms - osteoblasts make osteoid, fibrocartilaginous callus now bony callus, hard/spongy bone consisitancy Bone remodeling - new osteons, remove excess material etc |
|
|
What factors can affect bone growth, repair and remodeling?
|
Mechanical stress - more osteoblast activity
Nutrition - calcium, phosphorus (Ca phosphates), vit A (stimulates osteoblasts) K , B12 (matrix proteins), C (collagen formation), D ( Ca absorption) |
|
|
What happens to bones during prolonged periods of inactivity?
|
Osteoblast activity goes down
Osteoclast activity outweighs it Decrease in bone mass |
|
|
Why do athletes have stronger bones than sedentary people?
|
Mech. stress stimulates osteoblasts
More bone production |
|
|
How does vitamin D influence bone structure?
|
Essential for adequate Ca2+ absorption
Mineralization of bones Made by keratinocytes when exposed to UV; also from diet Active form - calcitriol - a hormone converted from inactive form in kidneys |
|
|
How does vitamin C influence bone structure?
|
Needed for collagen formation
|
|
|
Identify the primary hormones that regulate bone growth and development. What is the general function of each of the hormones identified?
|
Growth hormone (hGH) - made in anterior pituitary, causes production of IGF
Insulin-like growth factors (IGFs) - promotes bone growth for kids Thyroid hormones - stimulate osteoblast; promote metabolic rate Sex hormones - estrogens and androgens/testosterone; growth spurt, pelvic width, height diff, when osteocyte activity will over take chondrocyte @ epiphesial plates |
|
|
What is the impact on the skeleton of rising levels of sex hormones at puberty?
|
Estrogens vs. androgens/testosterone - width of pelvis, height, growth spurt, when osteocyte activity overtakes chondrocyte activity at epiphesial plates
|
|
|
What is the most important hormone regulating blood calcium levels and calcium storage in adults?
|
Parathyroid hormone (PTH)
|
|
|
What is the function of the parathyroid hormone?
|
Increases when blood Ca2+ is too low
- osteoclasts resorb bone - decreases rate of Ca excretion in kidneys - conversion of vit. D to active form (for Ca2+ absorption in small intestine) |
|
|
What are the target sites for the action of the parathyroid hormone?
|
- Osteoclasts in bone
- Kidneys (to affect Ca secretion and vit. D activation) |
|
|
What effect does parathyroid hormone have at its target sites?
|
- Osteoclasts resorb bone
- Kidneys excrete less Ca (resorbs more back into blood) - Kidneys activate vit. D, from cholecalciferol (which was made by keratinocytes) to calcitriol, which helps the absorption of Ca in small intestines |
|
|
What is the function of calcitonin?
|
- Secreted by thyroid
- Blood Ca2+ levels decrease - Important in children, who need it in their bones, and in pregnant/lactating women |
|
|
What are the target sites for the action of calcitonin?
|
- Osteoclasts
- Bone matrix - Kidneys |
|
|
What effect does calcitonin have at its target sites?
|
- Inhibits osteoclasts
- Enhances mineralization of bone matrix - Increases rate of Ca2+ excretion by kidneys |
|
|
How does aging affect the skeleton?
|
- Decreased rate of protein synthesis; less fiber and collagen content, so less tensile strength
- Demineralization - loss of Ca and other minerals from matrix |
|
|
Metaphysis
|
- The wider portion of a long bone adjacent to the epiphysial plate
- The part of the bone that grows during childhood |
|
|
Osteomalacia
|
Softening of bone in adults due to lack of vit. D
|
|
|
Diploe
|
The internal layer of a spongy bone in flat bones
|
|
|
Where is the metaphysis? What is the functional significance of this part of the bone?
|
- Wider portion of long bone adjacent to epiphysial plate
- Where the bone grows; epiphysial plates located here |
