Principles of Anatomy and Physiology: Chapter 6: Bone Tissue Flashcards


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1

Bone (osseus) tissue

Forms most of the skeleton, the framework that supports and protects out organs and allows us to move

2

The fuctions of bone tissue and the skeletal system

  • Provide support of soft tissues & attachment sites for muscles, creating a framework for the body
  • Protection from injury is afforded to internal organs by bones which overlie and/or surround them
  • Movement is facilitated since bone provide leverage for muscle contraction
  • Mineral homeostasis (calcium & phosphorus) occurs as minerals are stored in bones and can be mobilized when needed elsewhere in the body
  • Blood cell production occurs in the red bone marrow formed in certain bones
  • Storage of energy occurs in the lipids found in yellow bone marrow
3

Four types of connective tissue

  • Cartilage
  • Bone
  • Bone marrow
  • Periosteum
4

Parts of a typical long bone

  • Diaphysis (shaft)
  • Epiphyses (ends)
  • Metaphysis
  • Articular cartilage
  • Periosteum
  • Medullary (marrow) cavity
  • Endosteum
5

Bone (osseus) tissue consists

Widely separated cells surrounded by large amounts of matrix

6

The four principal types of cells in bone tissue

  • Osteoprogenitor cells
  • Osteoblasts
  • Osteocytes
  • Osteoclasts
7

The matrix of bone contains

  • Abundant mineral salts (hydroxyapatite)
  • Calcium carbonates
  • Calcification/mineralization
  • Mineral salts confer hardness on bone while collagen fibers give bone its great tensile strength
8

Depending on the size and distribution of the spaces between the hard components of bone, the regions of a bone may be categorized as

Compact or spongy bone

9

Compact (dense) bone tissue consists

  • Osteons (Haversian systems) with little spaces between them
  • Lies over spongy bone & composes most of the bone tissue of the diaphysis
  • Functionally, protects, supports, and resists stress
10

Spongy (calcellous) bone

  • Does not contain osteons
  • Contains trabeculae surrounding many red marrow-filled spaces
  • Forms most of the structure of short, flat, and irregular bones, and epiphyses of long bones
  • Functionally, stores red marrow and provides some support
11

Vessels

Needed to supply the various bone tissues with bone nutrients and wast disposal through a number of interconnective canals in the bone matrix

12

Vessels supply bone tissue by

  • The nutrient artery passing through the nutrient canal and sends branches into the central Haversian canals to provide for osteocytes
  • Artery continues into the medullae to supply blood for the marrow and osteocells via the epiphyseal artery
  • The periosteal arteries pass through Volkman's canals to a multitude of vessels that supply the outer compact bone region
13

Nerve follow vessels into bone tissue and the periosteum to

Sense damage and transmits pain messages

14

Bone forms by a process that begins when mesenchymal cells become transformed into osteoprogenitor cells

Ossification (osteogenesis)

15

Osteoprogenitor cells

  • Undergo cell division
  • Give rise to cells that differentiate into osteoblasts and osteoclasts
16

The process of ossification begins

During the sixth or seventh weeks of embryonic life and continues throughout adulthood

17

The two types of ossification

  • Intramembranous ossification
  • Endochondral (intracartilaginous) ossification
18

Intramembranous ossification occurs

  • Within fibrous membranes of the embryo and the adult
  • Ossification centers forms frommesenchymal cells as they convert to osteoblasts and lay down osteoid matrix
  • Matrix surrounds the cell and then calcifies as the osteoblast becomes an osteocyte
  • The calcifying matrix centers join to form bridges of trabeculae that constitute spongy bone with red marrow between
  • The periosteum first forms a collar of spongy bone that is then replaced by compact bone
19

Endochondral (intracartilaginous) ossification refers to

  • The formation of bone with a hyaline cartilage model
  • The primary ossification center of a long bone is in the diaphysis
  • Cartilage degenerates, leaving cavities that merge to form the medullary cavity
  • Osteoblasts lay down bone
  • Sedondary ossication centers develop in the epiphyses, where bone replaces cartilage, except for the epiphyseal plate
20

The epiphyseal plates consists of four zones

  • The zone of resting cartilage
  • The zone of proliferating cartilage
  • The zone of hypertrophic cartilage
  • The zone of calcified cartilage
21

Because of the activity of the epiphyseal plate

The diaphysis of a bone increases in length by intersitial growth

22

Bone grows in diameter as a result of

Intersitial and appositional addition of new bone tissue by osteoblasts around the outer surface of the bone and to a lesser extent internal bone dissolution by osteoclasts in the bone cavity

23

Human growth hormone (hGH) and insulin-like growth factor (IGF) stimulate

Bone deposition and changes during growth, in addition to thyroid hormone, parathyroid hormone, and calcitonin

24

Variation from normal levels of hGH and IGF can lead to

Either gigantism or dwarfism

25

At puberty the sex hormones, estrogen and testosterone stimulate

Sudden growth and modifications of the skeleton to create the male and female forms

26

Remodeling

Ongoing replacement of old bone tissue by new bone tissue

27

Old bone is constantly destroyed by

Osteoclasts

28

New bone is constructed by

Osteoblasts

29

Fracture

Any break in bone

30

Fracture repair involves

  • Fracture hematoma
  • Procallus
  • Conversion of the fibricartilaginous callus into the spongy bone of a bony (hard) callus
  • Remodeling of the callus to nearly original form
31

Fracture hematoma

Formation of a clot

32

Procallus

Organization of the fracture hematoma into granulation tissue

33

The types of fractures include

  • Partial
  • Complete
  • Closed (simple)
  • Open (compound)
  • Comminuted
  • Greenstick
  • Spiral
  • Transverse
  • Impacted
  • Displaced
  • Non-displaced
  • Stress
  • Pathologic
  • Pott's
  • Colles'
34

Bone is the major reservoir for

Calcium

35

The blood level of calcium ions is very closely regulated due to

Calcium's importance in cardiac, nerve, enzyme, and blood physiology

36

An important hormone regulating calcium exchange between bone and blood , secreted by the parathyroid glands, and increases blood calcium levels

Parathyroid hormone (PTH)

37

Another hormone that contributes to the homeostasis of blood calcium, secreted by the thyroid gland, and decreases blood calcium levels

Calcitonin (CT)

38

Within limits, bone has the ability to alter its strength in response to mechanical stress by

Increasing deposition of mineral salts and production of collagen fibers

39

Removal of mechanical stress weakens bone through

Demineralizing (loss of bone minerals) and collagen reduction

40

Weight-bearing activities, such as walking or moderate weight-lifting

Help build and retain bone mass

41

The fist principal effect of aging on bone

Loss of calcium and other minerals from bone matrix (demineralization), which may result in osteoporosis

42

The second principal effect of aging on the skeletal system

Decreased rate of protein synthesis, resulting in decreased production of matrix components (mostly collagen) and making bone more susceptible to fracture

43

Around the fifth weeks of embryonic life, extremities develop, which consts of mesoderm and ectoderm

Limb buds

44

By the sixth week, a constriction around the middle portion of the limb buds produce

Hand and foot plates, which will become hands and feet

45

Notochord

Flexible rod of tissue that lies in a position where the future vertebral column will develop

46

Osteoporosis

Decreased in the amount & strength of bone tissue owing to decrease in hormone output and bone resorption outpaces bone formation

47

Paget's disease

Characterized by massive osteoclastic resorption and extensive bone formation