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bio 223 > ch 6 > Flashcards

ch 6 Flashcards

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Biology 101 flashcards
1
Q

skeletal system functions

A
  1. support: bone supports muscle
  2. storage of minerals and lipids: calcium and yellow bone marrow
  3. blood cell production (red bone marrow): hematopoiesis/ hemopoiesis= process of blood cell production
  4. protection: i.e. organs, lungs, brain
  5. leverage (force of motion)
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2
Q

general shapes of bones

A

A) long bone: humerus
B) irregular bone: sphenoid bone, vertebral
C) flat bone: sternum, skull
D) short bone : talus, patella, scaphoid

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3
Q

long bone

A

Structure:

diaphysis: the shaft, heavy wall of compact bone, or dense bone; central space called medullary (marrow) cavity
epiphysis: wide part at each end, articulation with other bones, mostly spongy (cancellous or trabecular) bone, covered with compact bone (cortex): layer called cortical bone

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4
Q

matrix of bone

A

organic matrix: collagen fibers, organic matrix= osteoid
collagen fibers provide tensile strength and flexibility, but offer little resistance to compression forces. bone cells
inorganic matrix: gives rigidity to bone and provides compression strength, minerals
calcium salts: calcium phosphate, calcium hydroxide, calcium carbonate; minerals: sodium magnesium, flouride

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5
Q

structure of compact bone

A

osteon (Haversian system) is the basic unit
osteocytes are arranged in concentric lamellae
around a central canal (haversian canal) containing blood vessels.
perforating canals (volkmann’s canals)
-perpendicular to central canal
-carry blood vessels into bone marrow.
-nutrients in blood diffuse through canaliculi to reach osteocytes

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6
Q

types of lamellae

A 
concentric lamellae
-contains a central canal
-gives us osteon
circumferential lamellae
-lamellae wrapped around the long bone
-bind osteons together
-found at the outer and inner bone surfaces
-covered by periosteum or endosteum
-doesn't form osteon
interstitial lamellae
-fill in spaces between osteons in compact bone
-remnants of almost completely recycled osteons
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7
Q

structure of spongy bone

A

does not have osteons, no central canals, no concentric lamellae
boney matrix forms meshwork of supporting thin columns called trabeculae
trabeculae have no blood vessels
located whee bones are not heavily stressed, but where stresses arrived from many directions.
lighter than compact bone
spaces between trabeculae is filled with red bone marrow
-vascularized
-site of blood cell production (hemopoiesis)
-supplies nutrients to osteocytes.
yellow bone marrow
-in some bones, spongey bone holds yellow bone marrow
-stores fat, no blood cells being made.

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8
Q

periosteum

A

periosteum: external membrane
-covers all bones except parts enclosed in joint capsules and at articular surfaces
-made up of an outer, fiberous layer called dense irregular collagenous CT, and inner cellular layer (osteogenic layer)
-perforating fibers (sharpey’s fiber): thick bunkles of collagen fibers of the periosteum; connect with collaagen fibers in bones (secures the periosteum to underlying bone)
functions
1. isolates bone from surrounding tissues
2. provides a route for circulatory and nervous supply
3. participates in bone growth and fracture repair
4. serves as attachment point for ligaments and tendons

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9
Q

endosteum

A

internal membrane. strictly cellular no fibrous layer
a thin membrane composed of single layer of endosteal cells: osteoblast, osteoprogenitor, osteoclasts
lines the medullary (marrow) cavity
covers trabeculae of spongy bone
lines inner surface of the canals that passes through compact bone
active in bone growth, repair, and bone remodeling

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10
Q

red bone marrow vs yellow bone marrow

A

red bone marrow located in spaces between trabeculae
-vascularized
-site of blood cell production (hemopiesis)
-supplies nutrients to osteocytes
Yellow bone marrow
-spongy bone holds yellow bone marrow
-yellow because it stores fat

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11
Q

osteocytes

A

osteocytes: mature bone cells, accounts for most of the bone cell population, amitotic, confined within a lacuna
functions
1. maintain and monitor protein and mineral content of surrounding matrix
2. participate in the repair of damaged bone

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12
Q

osteoblasts found in periosteum and endosteum

A

turns to osteocyte
produce new bone (bone forming cells): process called osteogenesis= bone deposition
they make and release proteins and other organic components of the organic matrix of bone
promotes deposition of calcium salts in organic matrix
bone deposition: addition of minerals and collagen fibers to bone by osteoblast: making bone

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13
Q

osteoprogenitor (osteogenic cells) found in periosteum and endosteum

A

arise from mesenchymal cells: connective tissue stem cells
maintains the population of osteoblasts
important in repair of fractures and bone remodeling
found in the inner, cellular layer of the periosteum, endosteum and in the lining of passageways containing blood vessels that penetrate the matrix of compact bone

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14
Q

osteoclasts found in periosteum and endosteum

A

bone destroying
destroys or erodes bone: osteolysis or bone resorption
giant cells with 50+ nuclei
derived from stem cells that produce macrophages
secrete acids and digestive enzymes that dissolve bony matrix and releases the stored minerals into blood

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15
Q

intramembranous ossification (dermal ossification)

A 
dense collagenous ct starting tissue
bone forms directly within mesenchyme
simpler type of ossification
occurs in flat bones of the cranium, mandible, clavicle only.
not common
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16
Q

endochondral ossification

A

bone forms within hyaline cartilage starting tissue
process begins in the second month of development
occurs in essentially all bones of the skeleton below the base of the skull (except clavicles)
all the other bones

17
Q

bone remodeling

A

bone resorption: removal of minerals and collagen fibers by osteoclast
bone deposition: addition of minerals and collagen fibers by osteoblasts
bone continually remodels, recycles, and replaces
-bone building (osteoblasts) and bone recycling (osteoclasts) must balance
- goes on throughout life as part of normal bone maintenance
involves the continuous recycling and renewal of organic and inorganic components of the bony matrix
gives ability to adapt to environmental stress
involves the osteocytes, osteoblasts, and osteoclasts

18
Q

longitudinal growth

A

interstitial growth: vertical growth occurs at the epiphyseal growth plate of long bones
4 zones
1. zone of resting cartilage (resting zone): non-dividing chondrocytes
2. zone of proliferating cartilage : chondrocytes actively divide and produce new cartilage
3. Zone of hypertrophic cartilage (degenerating zone)
chondrocytes die and leave an open space to be filled in with osteoblasts
4. zone of calcified cartilage (ossification zone): osteoblast begin the process of osteogenesis

19
Q

appositional growth

A

increase in the diameter and thickness of bone
can happen throughout life
growth at surface

20
Q

epiphyseal growth

A

epiphyseal growth plate=cartilage.

epiphyseal line: bone

21
Q

exercise, hormones and nutrition

A

excercise: mineral recycling allows bones to adapt to stress; heavily stressed bones become thicker and stronger.
bone degeneration: bone degenerates quickly, up to one third of bone mass can be lost in a few weeks of inactivity.
nutritional and hormonal factors: dietary source of calcium and phosphate salts.
-calcitriol: hormone, active form of vitamin D3
-helps absorb calcium and phosphorus from digestive tract
-vitamin C required for collagen syntheses
- sex hormones: stimulate osteoblast activity and the synthesis of bone matrix; estrogens stimulate epiphyseal closure earlier than androgens
-parathyroid hormone: stimulates osteoclast activity; elevates calcium ion concentrations in body fluids
-calcitonin: inhibits osteoclast activity; promotes calcium loss by kidneys; reduces calcium loss by kidneys; reduces calcium ion concentrations in body fluids

22
Q

fracture

A

a crack or break in bone
4 steps
1. fracture hematoma (mass of clotted blood)
-6-8 hours, after a fracture blood escapes from ruptured blood vessel and forms a fracture hematoma
2. fibrocartilaginous callus: tissue repair begins; fibrocartilaginous callus fills space between the ends of the broken bone for about 3 weeks.
3. Bony callus: osteoblasts produce trabeculae of spongy bone and convert the fibrocartilaginous callus to bone calls joining the broken bones together. lasts 3-4 months
4. remodeling: osteoblasts build new compact bone reforming the bone collar; osteoclasts absorb the spongy bone creating new medullary cavity

23
Q

calcitonin and parathyroid hormone

A

homeostasis maintained by calcitonin and parathyroid hormone: control storage, absorption, and excretion

  • parathyroid hormone: produced by parathyroid glands. increases calcium ion levels by: stimulating osteoclasts, increasing intestinal absorption of Ca2+, decreasing calcium excretion at kindneys
  • calcitonin: secreted by C cells (parafollicular cells) in thyroid; decreases calcium ion levels by: inhibiting osteoclast activity, decreasing intestinal absorption of Ca2+, increasing calcium excretion at kidneys
24
Q

fracture types

A

open (compound): broken ends of the bone protrude through the skin. closed (simple) fracture does not break the skin

comminuted: bone is splintered, crushed, or broken into pieces at the site of impact, and smaller bone fragments lie between the two main fragments
greenstick: partial fracture in which one side of the bone is broken and the other side bends. occurs only in children
impacted: one end of fractured bone is forcefully driven into the interior of the other
pott: fracture of distal end of the lateral leg bone, with serious injury of distal tibial articulation
colles: fracture of the distal end of the lateral forearm bone in which distal fragment is displaced posteriorly

25
Q

bone mineral density

A

total amount of bone mass in a defined area
for specific bone: total amount of mineral content per unit area of bone
BMD measurement can help predict the risk of bone fracture (indicator of overall bone strength and health)
methods to measure BMD:
1. dual energy x-ray absorptiometry (DEXA): most common technique to determine the BMD. Focuses on the hip bone and spine
very small amount of x-ray energy that passes through bone is measured: total amount energy that penetrates the bone depends upon thickness of bone, using this information and define area of bone, amount of calcified tissue in grams per unit. used in osteoporosis and osteopenia patients

bio 223 (11 decks)

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