Chapter 6 Flashcards

The Skeletal System: Bone Tissue

1
Q

What are the six functions of the skeletal system

A

1) provides support
2) protects internal organs
3) assists in movement
4) stores & release Ca & P
5) participates in blood productions (hemopoiesis)
6) Stores triglycerides in adipose cells of yellow marrow. (used in energy release)

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2
Q

Structure of a long bone

The shaft of the bone is called

A

Diaphysis

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3
Q

Proximal and distal ends of the bone are called

A

Epiphyses

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4
Q

The epiphyseal growth plate is found in this part of the bone

A

metaphysis

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5
Q

List 4 structures of the bone

A
  • Diaphysis - shaft
  • Epiphyses - ends
  • Metaphysis - epiphyseal growth plate
  • Epiphyseal line
  • Articular cartilage - lines the joints and caps ends of bones
  • Periosteum - protects, repairs, nourishes and provides attachment site
  • Medullary cavity - marrow cavity
  • Endosteum - has bone forming cells
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6
Q

The epiphyseal line is formed when?

A

When a bone stops growing in length (age 14 - 24), the cartilage in the epiphyseal plate is replaced with bone

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7
Q

Osseous (bone) tissue is what type of tissue

A

Connective

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8
Q

What are some characteristics of osseous (bone) tissue

A
  • widely scattered cells
  • large amount of extracellular matrix
  • rich blood supply
  • nerve supply
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9
Q

There are 4 types of bone cells. Which of the following is able to differentiate into other bone cell types:
1) Osteoprogenitor cells
2) Osteoblasts
3) Osteocytes
4) Osteoclasts

A

1 - Osteoprogenitor = bone stem cells
it is the only bone cell able to undergo cell division

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10
Q

These are the bone building cells

A

OsteoBlasts

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11
Q

Mature bone cells are ________

A

Osteocytes

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12
Q

Osteoclasts serve what function:
a) build cells
b) bone resorption
c) undergo cell division

A

b) bone resorption

Or bone remodeling

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13
Q

This bone cell type remodels bones and releases Calcium

A

Osteoclasts

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14
Q

Osteocytes are found:
A) deep in layers of periosteum and the marrow
B) growing portions of bone (periosteum & endosteum)
C) entrapped in matrix
D) bone surfaces and at sites of old, injured, or unneeded bone.

A

C) entrapped in matrix.
They maintain mineral concentration of matrix and maintain bone tissue

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15
Q

you can find this bone cell in growing portions of the bone: periosteum and endosteum

A

Osteoblasts

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16
Q

What are the two types of bones and roughly what percentage do they make up in the body

A

1) Compact - 80%
2) Spongy - 20%

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17
Q

Compact bone forms the hard exterior of the bone or fills the interior cavity

A

hard exterior

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18
Q

Which of the following has a marrow cavity:
1) Compact Bone
2) Spongy bone

A

1) compact bone

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19
Q

Spongy bones form the major part of long bones
T/F

A

False
Spongy bones form a major part of the short bones (wrists and ankles)

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20
Q

Compact bones can withstand high weights up to:
a) 500 lbs
b) 1000 lbs
c) 5000 lbs
d) 8000 lbs

A

c) 5000 lbs

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21
Q

Spongy bones provide structural support
T/F

A

F - spongy bones act as a buffer for compact bones

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22
Q

which of the two types of bones is higher in Ca
compact or spongy?

A

compact

23
Q

Marrow is found in bone the bone tissue types. Which contains the yellow marrow and which contains red marrow

A

Compact - yellow marrow
Spongy - red marrow

24
Q

Osteogenesis or Ossification are alternative names for___________

A

Bone formation

25
Q

In what 4 situations does ossification occur?

A

1) Fetal development
2) bone growth (before adulthood)
3) bone remodel (when new bone replaces old)
4) fracture healing

26
Q

Bone formation takes place in 2 forms: Intramembranous and Endochondral.
What is the difference between these two?

A

Intramembranous: bone form directly within the mesenchyme (arranged in sheet like layers that resembles membrane)

Endochondral - bone forms within hyaline cartilage that develop from mesenchyme

27
Q

What are the 4 steps of intramembranous ossification

A

1) Development of ossification center - cluster of cells form

2) Calcification - Ca and other minerals deposited and ECM hardens

3) Formation of trabeculae: ECM develops into trabeculae that fuse to form spongy bone around BV

4) Development of periosteum: mesenchyme at the periphery of bone develops in periosteum

28
Q

Endochondral Ossification is the replacement of cartilage by bone. What are the 6 steps of endochondral

A

1) development of cartilage model - cells form into the general shape of the future bone

2) growth of cartilage model - cell division of chondrocytes

3) development of primary ossification center - bone tissue replaces cartilage in diaphysis

4) development of medullary (marrow) cavity - osteoclasts breakdown bone to form cavity

5) development of secondary ossification centers - occurs in the epiphyses of the bone

6) formation of articular cartilage and epiphyseal plate - bone structures consist of hyaline cartilage

29
Q

Interstitial (endogenous) growth results in ___________ increase

A

length

30
Q

Appositional (exogenous) growth results in increase in ___________

A

thickness

31
Q

What are the two major events in bone growth in length

A

1) Interstitial growth of cartilage on the epiphyseal side of the epiphyseal plate and
2) Replacement of cartilage on the diaphyseal side of the epiphyseal plate with bone by endochondral ossification.

32
Q

What are the four stages of Endochondral Ossification (bone replacement)
Both osteoblasts and osteoclasts are needed to thicken

A

1) Ridges in periosteum create groove for periosteal BV

2) Periosteal ridges fuse and form endosteum-lined tunnel. (former periosteum becomes endosteum)

3) Osteoblasts in endosteum build concentric lamellae inward toward tunnel center forming a new osteon

4) bone thickens as osteoblasts continue to build lamellae. Osteon formation repeats.

33
Q

What are 3 factors that affect bone growth and remodeling

A

1) minerals - CA, P, Mg, Mn, F
2) Vitamins - A, C ,D, K
3) Hormones

34
Q

Osteoblast activity requires what vitamin?

A

vitamin A

35
Q

Collagen need which vitamin

A

Vitamin C

36
Q

Calcium absorption from gut to blood requires this vitamin

A

Vitamin D

37
Q

bone protein synthesis need which vitamins

A

Vitamin K and B12

38
Q

List 3 hormones and how they affect bone growth and remodelling

A
  • Insulin growth factor (IGF): during childhood
  • T3, T4 : Osteoblasts
  • Insulin: Bone proteins
  • Sex hormones (estrogen & testosterone) - osteoblasts @ puberty
  • Calcitonin - inhibits osteoclast resorption
39
Q

What are the 3 phases of repair (that take place in 4 steps)

A

1) Reactive
2) Reparative
3) Remodeling

40
Q

Define a stress fracture

A
  • Fracture without visible break.
  • Series of microscopic fissures.
  • result from repeated stressors like: running, jumping, and dancing, can also be caused by disease (ex. osteoporsis)
41
Q

at what phase of the bone repair does a blood clot form?

A

reactive phase
usually within 6 - 8 hours
this phase can last several weeks

42
Q

hard and soft calluses form during what stage of bone repair

A

reparative phase
- fibrocartilaginous callus (soft) forms in approx 3 weeks and new BV form.
- In 3 - 4 months the callus hardens and becomes bony

43
Q

what is the final phase of bone repair

A

remodeling
other portions of the repair are reabsorbed by osteoclasts

44
Q

A PTH (parathyroid hormone) negative feedback lower is used when____

A

blood Ca levels are low.

45
Q

Which are the effectors in a PTH feedback and how to they increase blood calcium levels

A

Osteoclasts (bones) - release Ca
Kidneys - Ca is reabsorbed from urine by the kidneys

46
Q

What hormone does the parathyroid release

A

PTH

47
Q

What hormone does the thyroid gland release when it detects an increased level of Ca (+10mg)

A

Calcitonin

48
Q

What does calcitonin do?

A

inhibits osteoclast activity

49
Q

at homeostasis what level of Ca should there be

A

10mg/dL

50
Q

How does exercise contribute to bone health?

A

Mechanical stress increases absorption of mineral salts and production of collagen fibers by osteoblasts

51
Q

When bone resorption outpaces deposition (osteoclasts outpace osteoblasts), what occurs?

A

a decrease in bone mass
prevalent in older people especially post- menopause

52
Q

two main effects of aging on bone tissue are:

A
  • Loss of mass (demineralization): starts around age 35 and continues until 30% of Ca in bones is lost.
  • Brittleness: due to decreased rate of protein synthesis and loss of collagen fibers and tensile strength.
53
Q

osteoporosis is

A

porous bones.

mainly affects women (they have less bone mass than men and decreased estrogen after menopause)