Chapter 6 A&P1

medullary cavity

children (red marrow); adults (yellow marrow in limb bones and skull) with the rest of the marrow being the red marrow type.

interstitial growth?

chondrocytes divide within tissue to matrix (cartilage growth)

chondrocytes

cells that maintain matrix and have lacunae

epiphyseal plate

growth plate (hyaline cartilage) until growth stops.

stem cells: mmesenchyme (osteochondral progenitor cells)

have ability to become chondroblasrts or osteoblasts

external cllus

osteoblasts and chondroblasts. bone/ cartilage collar stabilizes two pieces.

Chondroblasts

cells that form matrix

closure of epiphyseal plate

when epiphyseal plate is ossified -> epiphyseal line

32.What are the four steps of bone repair?

1) Hematoma Formation 2) Callus Formation 3) Callus ossification 4) Bone Remodeling

4 steps of bone repair?

1)hematoma formation: blood from blood vessels = clot 2) callus formation: tissue that forms at fracture site- connects broken ends 3) callus ossification- callus replaced by woven bone 4) bone remodeling- replacement of cancellous bone by compact bone

1.Name the four components of the skeletal system.

1. Bones 2. Cartilage 3. Tendons 4. Ligaments

3.What are the three types of cartilage? Which type is more closely associated with bone? ;

1. Hyaline cartilage 2. Fibrocartilage 3. Elastic cartilage Hyaline cartilage is mostly associated with bone.

effects of old age on skeletal system

1. bone matrix decreases 2. bone mass decreases 3. bone loss 10 fold after menopause: causes deformity, loss of height, pain, stiffness, stooped posture, & loss of teeth; increased fractures.

endochondral ossification

1. cartilage formation begins -fourth week 2. base of skull, part of mandible, epiphyses of the clavicles, most remaining bones 3. some ossification begins - week eight embryo; some does not begin until 18-20 years of age (medial epiphysis of clavicles)

compact bone characteristics

1. central (haversian) canals: parallel to long axis 2. lamellae: concentric; circumferential; interstitial 3. osteon or haversian system: central canal, contents, associated concentic lamellae and osteocytes 4. perforationg or volkmann's canal: perpendicular to long axis contains blood vessels 5.circulation in bone

woven bone 3 characteristics

1. during fetal development 2. during fracture repair 3. remodeling= removing old none/ adding new (woven bone remodeled into lamellar bone)

intramembranous ossification

1. forms in connective tissue membrane from embryonic mesenchyme (many skull bones, part of mandible, diaphyses of clavicles.) 2, centers of ossification- in C.T. membrane where ossification begins fontanels: large memrane- covered spaces between developing skull bones; unossified

classified on basis of direction of fracture

1. linear 2. transverse 3. spiral 4. olique 5. stellate - radiating out from a central point

bones shapes

1. long- upper and lower limbs 2. short- carpals and tarsals 3. flat- ribs, sterum, skullm scapulae 4. irregular- vertebrae, facial

lamellar bone characteristics

1. sheets= lamellae. fibers oriented in one direction in each layer) - layers 2. each layer has a different directions - > strength

factors that affect bone growth

1. size/ shape - genetically 2. nutrition- lack calcium, protein during growth ->bones small rickets = lack of vitamin D scurvy= dificiency of vitamin c 3. growth hormone- interstitial cartilage growth and appositional bone growth a. thyroid hormone- all tissue b. sex hormones- growth at puberty but closure of epiphyseal plates

23.Name and describe the events occurring in the four zones of the epiphyseal plate. Explain how the epiphyseal place remains the same thickness while the bone increases in length

1. zone of rest-cartilage attaches to the epiphysis. 2. zone of proliferation-new cartilage is produced on the epiphyseal side of the plate as the chondrocytes divide and form stacks of cells. 3. zone of hypertrophy-chondrocytes mature and enlarge. 4. zone of calcification-matrix is calcified and the chondrocytes die. The thickness of the epiphyseal plate does not increase because the rate of cartilage growth on the epiphyseal side of the plate is equal to the rate of cartilage replacement by bone on the diaphyseal side of the plate.

hairline

2 sections of bone do not separate(skull)

39.What stimulates calcitonin secretion? How does calcitonin affect osteoclast activity?

An increase in blood Ca2+ stimulates the thyroid gland to secrete calcitonin. It decreases osteoclast activity by binding receptors on the osteoclasts.

29.Why is it important for bone remodeling to occur?

Bone remodeling converts woven bone into lamellar bone and functions in bone growth, changes in bone shape, adjustment of the bone to stress, bone repair, and calcium ion regulation of bod

12.Describe the structure of compact bone. What is an osteon? Name three types of lamellae found in compact bone.

Compact bone- Is denser and has fewer spaces than spongy bone. Osteon- It consists of a single central canal and associated concentric lamellae and osteocytes. 1.Concentric lamellae 2. Circumferential lamellae 3. Interstitial lamellae

8.Describe the formation of new bone by appositional growth. Name the spaces that are occupied by osteocyte cell bodies and cell processes

During appositional growth, new bone cells are made by osteoblasts and replace the old ones on the bones surface. One the osteoblasts are surrounded by the bone matrix, they become osteocytes. The space occupied by the osteocytes is called lacunae and the space that surrounds the ostecyte cell processes is called the canaliculi.

10.How is the organization of collagen fibers different in woven and lamellar bone? What process produces woven bone?

In Woven bones the organization of the collagen fibers are randomly oriented in many directions. In Lamellar bone the collagen fibers are organized into thin sheets or payers approximately 3-7 micrometers. The process that produces woven bone is bone remodeling.

Bone matrix

Is like reinforced concrete. Rebar = collagen fibers cement= hydroxyapetite 1. organic: collagen/ proteoglycans (35%) 2. inorganic: hydroxyapeptite. CaPO4 crystals (65%)

26.Explain how illness or malnutrition can affect bone growth. How do vitamins D and C affect bone growth?

It affects the rate of cell proliferation or the production of collagen and other matrix components. Without vitamin D children can get a disease called rickets, this is resulting from reduced mineralization of the bone matrix. Vitamin C deficiency results in bones and cartilage that are deficient in collagen because collagen synthesis is impaired.

37. Name the hormone that is the major regulator of Ca2+ levels in the body. What stimulates the secretion of this hormone?

Parathyroid hormone is the major regulator of CA 2+ levels in the body. When blood CA 2+ levels are too low, it stimulates an increase in the number of osteoclasts.

35.Why is remodeling of the ossified callus necessary?

Remodeling of the ossified callus is necessary because since woven bone is not as structurally strong as the original lamellar bone, then filling the gap between bone fragments with an internal callus of woven bone is not the end of the repair process. Repair cannot be complete until the woven bone of the internal callus and the dead bone adjacent to the fracture site are replaced my compact bone. As the internal callus is remodeled and becomes stronger, the external callus is reduced in size by osteoclast activity. The repaired zone usually remains slightly thicker than the adjacent bone, but the repair may be so complete that no evidence of the break remains.

List the four basic shapes of bones, and give an example of each.

The four basic shapes of bones are long (humerus), short (wrist bone), flat (ribs, skull), and irregular (facial

spongy (cancellous) bone characteristics

Trabeculae- interconnecting rods or plates of bone 1. spaces filled with marrow 2. covered with endosteum 3. oriented along stress lines

25.Describe how new osteons are produced as a bone increases in width.

When a bone grows in width slowly, the surface of the bone becomes smooth as osteoblasts from the periosteum lay down even layers of bone to form circumferential lamellae. The circumferential lamellae break down during remodeling to form osteons.

5 skeletal system functions?

a. Support: bone-hard & rigid; cartilage- flexible yet strong b. protection: skull; ribs; sternum; vertebrae (thoracic cavity) c. movement: tendons; ligaments d. storage: Ca2+; phosphorous and fat e. blood cell production: bone marrow

2 ways of growth?

a. appositional:: perichondrium adds new chondroblasrs at the periphery (outside) of the tissue b. interstitial: chondrocytes divide within the tissue ->matrix

short & irregular bone

a. compact bone surrounds spongy bone - similar to structure of epiphyses b. no diaphyses and not elongated (vertebrae, facial bones)

periosteum

a.outer- fibrous b. inner- single layer (osteoblatsts, osteoclasts and osteochondrial progenitor cells) c.tendon fibers continuous with periosteum d. sharpey's fibers: periosteal fibers penetrate through periosteum into bone- stengthen tendon attachment

internal callus

blood vessels grow into the clot, macrophages clean up debris, fibroblasts produce collagen and granulation tissue, chondroblasts to cartliage, then osteoblasts invade.

open(compound) fracture

bone break + open wound

epiphyseal line

bone stops growing in length

small communication channels extending through the bone matrix that connect osteocytes inside of lacunae are?

canaliculi

canacliculi

canals occupied by osteocyte cell processes

intersitial

cartilage growth

Matrix

collagen fibers (strength) + proteoglycans (resilency)

compact bone

dense

complete

does cross bone

articular cartliage

does not ossify- persists through life.

incomplete

doesn't extend across the bone

perichondrium

double layer C.T. sheath that covers cartilage

epiphysis

end of the bone (cancellous bone mostly)

Osteoblasts

form bone= ossification (osteogenesis) b. osteoblasts communicate through gap junctions. cells surround themselves by matrix. (lots of rough E.R. to make collagen fibers for bones)

greenstick

fracture on the convex side of the curve of a bone

33.How does breaking a bone result in hematoma formation?

hen a bone is fractured, the blood vessels in the bone and surrounding periosteum are damaged and a hematoma forms.

What do most bones develop from?

hyaline cartilage

centers of ossification

in C.T. membrane where ossification begins

trabeculae

interconnecting rods or plates of bone like scaffolding

bone development 2 methods of ossicfication

intramembranous ossification- in connective tissue membrane endochondral ossification - in cartilage - both methods of ossification produce woven bone that is then remodeled - cant tell the difference between the two

fontanels

large membrane-covered spaces between developing skull bones; unossified

lamellar bone

mature bone (sheets)

osteocytes

mature bone cells surrounded by matrix (maintin matrix) (nutrients diffuse through lacunae and canaliculi (gap junctions))

comminuted fractures

more than 2 pieces

appositional growth

new layers of bone on surface of old bone or cartilage (beneath periosteum)

closed

no break in skin

impacted fractures

one fragment is driven into the cancellous portion of the other fragment

lacunae

osteocyte spaces

woven bone

randomly oriented immature

osteoclasts

resorption of bone (getting rid of the old bones) a. ruffled border b. H+ ions and enzymes- digest bone c. multinucleated probably fusion of several cells

flat bones

sandwich of cancellous between compact bone

diaphysis

shaft( compact bone mostly)

endosteum

similar inner layer as periosteum (same type cells)

spongy (cancellous) bone

spaces with trabeculae