Histology (connective tissue, cartilage and bone) Flashcards Preview

CM Week 2 > Histology (connective tissue, cartilage and bone) > Flashcards

Flashcards in Histology (connective tissue, cartilage and bone) Deck (88)
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1
Q

What is the primary function of connective tissue?

A

To provide the structural support and connecting framework for all the other tissues of the body

2
Q

What is the main constituent of connective tissues?

A

fibers and extracellular matrix (ECM)

3
Q

What is extracellular matrix?

A

sound substance- represents a combination of collagens, noncollagenous glycoproteins, and proteoglycans surrounding the cells of connective tissue

4
Q

What is the resident cell of connective tissue?

A

fibroblast

5
Q

What is the fibroblast responsible for?

A

production and maintenance of the ECM

6
Q

What are the immigrant cells of connective tissue?

A

macrophages, mast cells, and plasma cells

7
Q

What are the important roles of connective tissue?

A

immune and inflammatory responses and tissue repair after injury.

8
Q

What does loose connective tissue contain and where is it normally found?

A

contains more cells than collagen fibers.

generally found surrounding blood vessels, nerves, and muscles

9
Q

What does dense connective tissue contain?

A

more collagen fibers than cells

10
Q

What are the 2 subsets of dense connective tissue

A

regular and irregular

11
Q

What is dense regular connective tissue?

A

when collagen fibers are preferentially oriented as in tendons, ligaments, and the cornea

12
Q

What is dense irregular connective tissue?

A

collagen fibers are randomly oriented as in the dermis of the skin and wall of the intestine

13
Q

What has an impact of the healing time of regular dense connective tissue?

A

it is generally poorly vascularized

14
Q

What are the 4 main components of the ECM?

A

glycosaminoglycans, proteoglycans, adhesive glycoproteins, and collagen

15
Q

What are glycosaminoglycans (GAGs)

A

long unbranched polysaccharides consisting of repeating disaccharide units.

16
Q

What molecules are highly negatively charged and associate with large amounts of water to create hydrated gels with high viscosity and low compressibility?

A

Glycosaminoglycans (GAGs)

17
Q

What are the specific GAGs of physiological significance?

A

hyaluronic acid, dermatan sulfate, chondroitin sulfate, heparin, heparin sulfate, and keratin sulfate

18
Q

What are proteoglycans?

A

family of macromolecules composed of a protein core to which at least one glycosaminoglycan is covalently bound.

19
Q

What is the most simple proteoglycan?

A

Decorin consists of a core protein and a single glycosaminoglycan.

20
Q

What is a more complex proteoglycan?

A

aggrecan, found in articular cartilage and consist of a core protein with many bound glycosaminoglycans

21
Q

What highly negatively charged molecules range in size from 50,000 Da to 3,000,000 Da?

A

proteoglycan

22
Q

What molecules help to organize and stabilize the matrix by interaction with the molecules (i.e collagen)?

A

proteoglycan

23
Q

What are proteoglycans a component of?

A

component of the basal lamina of epithelial cells and because of their negative charge create a barrier to the passage of positively charged molecules from the epithelium into other cells or connective tissues.

24
Q

What are adhesive glycoproteins a component of?

A

ECM of some tissues

25
Q

What is the function fo adhesive glycoproteins?

A

they help to facilitate the attachment of cells to the ECM and are also involved in affecting the growth, survival, morphology differentiation and motility of cells.

26
Q

What are 2 well known examples of ECM glycoproteins ?

A

modular protein laminin and fibronectin

27
Q

What do adhesive glycoproteins consist of?

A

disulfide-bonded subunits with binding sites for cells and other components of the ECM

28
Q

What are the most abundant types of collagen?

A

Type I, Type II, Type III

29
Q

What do Type I, Type II, Type III collagen form?

A

They form fibril of similar structure that provide tensile strength to tissues

30
Q

How is the collagen molecule formed?

A

3 collagen Alph-chains associate in a characteristic right-handed helix

31
Q

What characteristic amino acid sequence does each Alph-chain of collagen have?

A

every third amino acid is glycine, that allows for the proper formation of the title helix.

32
Q

What are the higher-order structures that individual collagen molecules associated together to form?

A

collagen fibers

33
Q

What is cartilage?

A

a specialized type pot connective tissue that consists of cells (chondrocytes) embedded in ECM

34
Q

In most cases what is cartilage surrounded by?

A

fibrous connective tissue layer called the perichondrium

35
Q

What does the perichondrium consist of?

A

an outer fibrous layer and an inner chondrogenic layer that contains stem cells that differentiate into new chondroblasts and chondrocytes.

36
Q

Why does cartilage have a modest repair capacity after injury?

A

because it is avascular and cells receive nutrition by diffusion through the ECM limiting the size that cartilage can attain

37
Q

What are the 2 mechanism that cartilage grows?

A
  1. interstitial growth by division of existing chondrocytes within the cartilage
  2. appositional growth by the production fo new chrondroblasts and chondrocytes at the surface of the cartilage from the stem cells in the perichondrium
38
Q

What are the 3 types of cartilage?

A

hyaline, elastic, and fibrous

39
Q

Where is hyaline cartilage found?

A

skeleton of the embryo, articular cartilage in joints, and cartage of the respiratory tract.

40
Q

Where is elastic cartilage found?

A

external ear and epiglottis

41
Q

Where is fibrous cartilage found?

A

intervertebral disks, menisci of the knee, pubic symphysis

42
Q

What cartilage(s) is not surrounded by a perichondrium?

A

fibrous

43
Q

What cartilage(s) are surrounded by a matrix of Type II collagen?

A

hyaline and elastic

44
Q

What cartilage(s) are surrounded by a matrix of Type I collagen?

A

fibrous

45
Q

What is bone?

A

a rigid inflexible connective tissue in which the ECM has become impregnated with salts of calcium and phosphate by a process called mineralization. it is highly vascularized and metabolically very active.

46
Q

What are the primary functions of bone?

A

to provide attachment sites for muscles
protect the soft tissue organs in the body
serve as a reservoir for calcium and phosphate ions

47
Q

What does the bone do in response to physical stresses and mineral needs of the body?

A

remodel and reshape

48
Q

What are the organic components of the ECM of bone?

A

organic matrix (osteoid) composed primarily of Type 1 collagen and proteoglycans.

49
Q

What are the 3 main noncollegenous glycoproteins in the organic matrix of bone (osteoid)?

A

osteoclacin, osteopontin, and osteonectin

50
Q

What are the organic components of the ECM of bone?

A

organic matrix (osteoid) composed primarily of Type 1 collagen and proteoglycans.

51
Q

What are the inorganic components of the ECM of bone?

A

inorganic matrix is called bone mineral and consists of calcium and phosphate salt called hydroxyapatite

52
Q

Where is 99% of the body’s store of Ca++ found?

A

hydroxyapatite of bone

53
Q

What contributes to the strength and rigidity of bone?

A

inorganic matrix

54
Q

What are the 4 major cell types of bone?

A

osteoblasts, osteocytes, osteoclasts, and osteoprogenitor cells

55
Q

Where are the osteoblast derived from?

A

the osteoprogenitor cells

56
Q

What are the main bone-forming cells?

A

osteoblasts

57
Q

What is the shape of the osteoblast and where is it found?

A

cuboidal-shaped cells

generally found on the surface of bone that actively deposits osteoid along the osteoblast-bone interface.

58
Q

What initiates and controls the mineralization fo the osteoid?

A

osteoblasts

59
Q

What are the proteins that osteoblasts express?

A

parathyroid hormone receptor, alkaline phosphatase, vitamin D3, IGF-1, Type I collagen, osteocalcin, osteopontin, osteoprotegerin (OPG), RANKL

60
Q

What are the proteins that osteoblasts express?

A

parathyroid hormone receptor, alkaline phosphatase, vitamin D3, IGF-1 receptor, Type I collagen, osteocalcin, osteopontin, osteoprotegerin (OPG), RANKL

61
Q

What does the alkaline phosphatase do in relation to the osteoblast?

A

a cell surface enzyme that produces high levels of phosphate ion during bone matrix synthesis. An important metabolic marker of bone formation.

62
Q

What is an important metabolic marker of bone formation?

A

alkaline phosphatase

63
Q

What does the vitamin D3 do in relation to the osteoblast?

A

regulates expression of osteocalcin a protein with high binding affinity for hydroxyapatite

64
Q

What does the IGF-1 receptor do in relation to the osteoblast?

A

binds IGF-1 produced by the liver and stimulates the growth of the long bones. Stimulates osteoid production

65
Q

What does osteocalcin do in relation to the osteoblast?

A

a non-collagenous protein required for bone mineralization

66
Q

What does Type I collagen do in relation to the osteoblast?

A

the major component of the osteoid matrix

67
Q

What does osteopontin do in relation to the osteoblast?

A

a non-collagenous protein that mediates the interaction fo osteoclasts with the bone surface

68
Q

What does osteoprotegerin (OPG) do in relation to the osteoblast?

A

a non-collegenous protein that functions as a decoy receptor for the RANK ligand (RANKL) and inhibits osteoclastogenesis

69
Q

What does the RANKL do in relation to the osteoblast?

A

a ligand for the RANK receptor present on osteoclast precursors and a receptor for OPG

70
Q

What is the initial extracellular matrix produced by osteoblast referred as?

A

primary or woven bone

71
Q

What characterizes the primary/woven bone of the osteoblast?

A

it is a matrix containing loose randomly oriented collagen fibers and low amounts of hydroxyapatite.

72
Q

What is the primary/woven bone matrix of the osteoblast remodeled into?

A

secondary or lamellar bone

73
Q

What characterizes the secondary/lamellar bones of the osteoblasts?

A

organized sheets of collagen fibers (lamellae) and high amounts of hydroxyapatite.

74
Q

Where do osteocytes arise from?

A

osteoblasts that have become surrounded by bone matrix stop producing osteoid, flatten out and transform into osteocytes.

75
Q

What are osteocytes?

A

highly branched cells with their cell body occupying small spaces, or lacunae, within layers of bone matrix. small channels the canaliculi course through the bone matrix and interconnect neighboring lacunae. Cell process of adjacent osteocytes are found within canaliculi and form gap junctions with adjacent cells.

76
Q

Where in the osteocyte does extracellular fluid (continent nutrients, calcium and other substances diffuse through?

A

cancliculi into the lacunae to support the osteocytes.

77
Q

What is the life span for osteocytes?

A

provided that it has access to sufficient nutrients their life span can be many years.

78
Q

What do osteocytes respond to?

A

force on the bone and release factor that can stimulate bone remodeling or turnover.

79
Q

What are osteoclasts?

A

large mutinucleated cells found on the surfaces of bone whose primary function is to degrade the bone matrix.

80
Q

Where are osteoclasts derived from?

A

monocyte precursors originating in the bone marrow.

81
Q

What is the specific process regulated by osteoblasts that transforms the monocyte precursors to active osteoclast ?

A

osteoclastogenesis

82
Q

What inhibits the activity of the osteoclast and causes its release from the bone surface?

A

binding of the hormone calcitonin

83
Q

When bone cells and matrix form a highly organized striation it is classified as what?

A

cortical (compact) or trabecular (cancellous) bone

84
Q

What type of bone has no osteons?

A

trabecular/cancellous bone

85
Q

What is calcium homeostasis?

A

the mechanisms by which the body maintains adequate calcium levels in order to prevent high plasma calcium or low plasma calcium both o which can have important consequences for health.

86
Q

What physiological processes is calcium homeostasis important for?

A

glandular secretion, muscle contraction and neuronal function

87
Q

What gland and hormone are triggered during hypocalcemia?

A

parathyroid gland; parathyroid hormone (PTH)

88
Q

What gland and hormone is triggered during hypercalcemia?

A

thyroid gland; calcitonin