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Flashcards in MICROSCOPIC ANATOMY Deck (149)
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1
Q

tissue

A

groups of cells with varying amounts of ECM that perform certain functions

2
Q

4 types of tissue

A
  1. epithelial (aggregated)
  2. connective (fixed and wandering; lots of ECM)
  3. muscular (elongated, contractile)
  4. nervous (intertwining, elongated processes; no ECM)
3
Q

steps for preparing tissue for microscopy

A

fixation, sectioning, staining

4
Q

epithelium

A
  • lines lumens to cover, protect and secrete/absorb with the help from microvilli projections
  • attached to connective tissue by basal lamina
  • cells are held together by cadherins and interdigitations with tight junctions/zonula adherens between them
  • simple (squamous, cuboidal, columnar; vessles, thyroid, intestine), pseudostratified (cuboidal, columnar; trachea, bronchi, nasal cavity) and stratified (squamous keratinized, squamous nonkeratinized, cuboidal, transitional, columnar; epidermis, mouth, genitals, bladder, conjunctiva)
5
Q

thin vs. thick skin

A

distinguished by the thickness of the epidermal layer

6
Q

layers of the epidermis

A
stratum basale (layer of stem cells)
stratum spinosum (mitotically active)
stratum granulosum (non-proliferating)
stratum lucidum (clear layer seen only in thick skin)
stratum corneum (keratinized cell "ghosts")
7
Q

keratinocytes

A

forms the epidermal water barrier

8
Q

melanocytes

A

responsible for differences in skin color

9
Q

Langerhans cells

A

play a role in delayed-type hypersensitivity reactions

*antigen presenting cells from bone marrow

10
Q

Merkel cells

A

function as sensitive mechanoreceptors

  • found mainly in stratum basale of thick skin
  • carcinomas are rare but hard to treat
11
Q

brush border

A

slightly longer complex of microvilli found on proximal renal tubule

12
Q

classification of epithelia

A

cell layers (simple, stratified, pseudostratified)

shape of cell (squamous, cuboidal, columnar)

presence of cilia/keratin (ciliated, keratinized)

  • endothelium= simple squamous (lining blood and lymphatic vessels)
  • myoepithelium= contractile cells (mammary, sweat, salivary)
  • mesothelilum= simple squamous (lining body cavities)
13
Q

epithelial cell renewal

A

finite life span and renew every couple of days based on where they are located

14
Q

epithelial response to stress

A

undergo atrophy (death), hypertrophy (enlargement), hyperplasia (increase in number), dysplasia (change in organization) or metaplasia (transformation to another cell type)

15
Q

function of skin

A

serves as a mechanical and permeability barrier receiving sensory and immunologic input and regulates body temperature and water loss to maintain homeostasis as the heaviest organ of the body (16% of body weight)

16
Q

parenchyma and stroma

A

parenchyma- cells responsible for main organ function

stroma- supporting elements or matrix of the organ

17
Q

colors formed by H, E and H&E stains

A

H- blue
E- pink
H&E- purple

18
Q

eosin

A

Na+ (dye)- acidic dye which stains cytoplasm, cytoplasmic filaments, collagen fibers and basement membrane

19
Q

hematoxylin

A

(dye)+Cl- basic dye which stains heterochromatin, nucleolus, the RER and sulfated GAGs

20
Q

basement membrane

A

basal lamina and the reticular lamina

21
Q

connective tissue

A

develops from embryonic mesoderm/mesenchymal cells and forms a continuum with the other three major tissue types for structural purposes

*has ECM that is made up of ground substance, protein fibers and tissue fluid

22
Q

resident and immigrant connective tissue cells

A

resident/fixed= locally derived and are mesenchymal cells, fibroblasts, reticular cells and adipose cells

immigrant/wandering= migrate from blood or bone marrow and are macrophages, mast cells, plasma cells and blood derived CT cells

23
Q

mesenchymal cells

A

precursors of connective tissue cells which have large nuclei and prominent nucleoli

*undifferentiated stem cells are called pericytes or adventitial cells when found near blood vessels

24
Q

fibroblasts

A

numerous and found all over with an oval nucleus, basophilic cytoplasm and several prominent nucleoli with the capability to participate in tissue repair

25
Q

what is the difference between a fibroblast and a fibrocyte?

A

fibroblast- mitotically active

fibrocyte- inactive

26
Q

reticular cells

A

form reticular fibers that form the netlike stroma of hematopoietic, lymphoid and adipose tissues

27
Q

adipocytes

A

specialized cells for lipid storage

28
Q

macrophages

A

derived from monocytes, are small with numerous vacuoles and participate in host defense as antigen-presenting cells secreting enzymes and cytokines

29
Q

mast cells

A

large, located near blood vessels and contain a small nucleus and basophilic granules containing contents that are released when surface receptors for IgE antibodies trigger degranulation by exocytosis for inflammation of allergic reactions

30
Q

plasma cells

A

primary producers of antibodies which are found in the medulla of lymph nodes and lamina propia of the stomach and intestines and differentiate from antigen-stimulated B lymphocytes

31
Q

ground substance

A

colorless and transparent mixture that binds cells to connective tissue fibers and is made up of GAGs (glycosaminoglycans) and structural glycoproteins

32
Q

3 types of connective tissue fibers

A

collagen
reticular
elastic

*long, slender protein polymers

33
Q

collagen fibers

A

the most abundant fiber type for shape and tensile strength that is greater than 50nm in diameter forming bundles and made up of type I collagen which appears white but stains pink with eosin

*3 groups: fibril forming collagens (visible by EM), linking/anchoring collagens (bind collagen fibers to each other and to ECM), sheet-forming collagen (meshwork for structural core of basement membrane)

34
Q

reticular fibers

A

less than 50nm with heavy glycosylation so the fibers stain black with silver salts and PAS-positive which are synthesized by fibroblasts, reticular cells, Schwann cells and smooth muscle cells

*reinforce smooth muscle layers

35
Q

elastic fibers

A

composed of elastin and range in diameter from 0.1 to 10 microns with cross-linking to create rubber band properties in areas where stretching is needed (ex. elastic ligaments and arteries)

  • pico-orcein and resorcin fuchsin stains it
  • Oxytalan- synthesized in first stage and comprised of fibrillin
  • Elaunin- formed as the amorphous protein elastin is deposited between oxytalan fibers
36
Q

Ehlers-Danlos type IV disease

A

faulty transcription or translation of type III collagen resulting in aortic and intestinal ruptures where reticular fibers normally reinforce smooth muscle layers

37
Q

Marfan’s syndrome

A

mutation in the fibrillin gene leading to a higher risk of aortic rupture and hypermobile joints

38
Q

connective tissue classification

A

connective tissue can be broken down into connective tissue proper, connective tissue with special properties and supporting connective tissue

connective tissue proper is split into loose/areolar and dense (dense is split into regular and irregular)

connective tissue with special properties can be broken down into adipose tissue, elastic tissue, hematopoietic/reticular tissue (lymphatic and myeloid) and mucous tissue

supporting connective tissue can be broken down into cartilage and bone

39
Q

loose connective tissue

A

a subset of connective tissue proper that has suspended fixed and wandering cells allowing regular movement of tissues and found in the mesentery, omentum, lamina propria of tubular organs and subcutic

*more cellular than dense CT

40
Q

dense connective tissue

A

a subset of connective tissue proper that can be classified as regular or irregular with fibroblasts as its predominant cell

regular- tendons, ligaments and cornea
irregular- organ capsules, periosteum and dermis of skin

41
Q

hematopoietic/reticular connective tissue

A

a subset of connective tissue with special properties and creates specialized microenvironments for cells in bone marrow, lymph nodes and the spleen

42
Q

adipose tissue

A

subset of connective tissue with special properties that can be broken down into unilocular (yellow/white) beneath skin and multilocular (brown due to capillaries and mitochondria) in human fetus

43
Q

mesenchymal cell to adipocytes

A

mesenchymal cell–> fibroblase and lipoblast

lipoblast–> multilocular adipocyte and unilocular adipocyte

44
Q

smooth muscle

A

not striated with a single spindle shaped nucleus arranged in bundles or sheets and innervated by the ANS that can regenerate after injury

45
Q

skeletal muscle

A

cross striated with many nuclei and innervated by cerebrospinal nerves which contract rapidly and are capable of regeneration

*made up of epimysium (dense irregular), perimysium (loose CT dividing muscle into fascicles) and endomysium (reticular fibers surrounding individual muscle fibers)

46
Q

what does cross-striation allow for?

A

the transmission of force and signal transduction

47
Q

titin

A

maintains the regularity of sarcomere structure

48
Q

satellite cells

A

responsible for skeletal muscle regeneration after injury through activation, proliferation and restoration even though they lack many cellular elements

*decreases with age

49
Q

type I skeletal muscle fibers (RED)

A
  • small
  • high myoglobin
  • many mitochondria
  • fatigue resistant
  • energy derived from oxidative-phosphorylation
  • contracts slowly
50
Q

type IIA skeletal muscle fibers (INTERMEDIATE)

A
  • intermediate size, myoglobin content and number of mitochondria
  • resistant to fatigue
51
Q

type IIB skeletal muscle fibers (WHITE)

A
  • greater diameter
  • low myoglobin content
  • fewer mitochondria
  • fatiguable
  • energy from anaerobic glycolysis
  • sudden contraction
52
Q

cardiac muscle

A

less obvious cross-striations that make branching fibers and will contract rapidly since it makes up the heart with only one spindle-shaped nucleus while being innervated by the ANS

53
Q

intercalated discs

A

interface between adjacent cardiomyocytes occurring at Z lines allowing for mechanical attachment of cells (macula adherens) and transmission of electrical and chemical stimuli (gap junctions)

54
Q

atrial natriuretic factor (ANF)

A

released in response to wall stretch to regulate cardiovascular homeostasis by controlling water balance, electrolyte balance and blood pressure

55
Q

Purkinje fibers

A

responsible for the final distribution of the electrical stimulus to the myocardium and found in the interventriular septum of the heart

56
Q

Purkinje fibers vs. cardiac muscle fibers

A

Purkinje fibers are larger, unusually shaped and richer in glycogen with myofibrils located at the periphery and rarely observed intercalated discs

57
Q

muscular dystrophies

A

intrinsic defect leading to progressive muscular weakness and wasting

58
Q

polymyositis

A

progressive disease that appears in adult life causing muscular weakness and tenderness that can be fatal

59
Q

neurogenic atrophy

A

caused from a motor neuron disease like anterior poliomyelitis or ALS (amyotrophic lateral sclerosis)

60
Q

histological criteria for diagnosing muscular diseases

A

size and shape, fiber distribution and degeneration, inflammation, changes in CT and special architectural features

61
Q

atherosclerosis

A

a disease process affecting smooth muscle in which the arteries are affected by a thickening of the inner portion and accumulation of cells in tunica intima and intracellular lipid

62
Q

diseases affecting the cardiac muscle

A

ischemic heart disease (MI)
inflammatory lesions of the heart (rheumatic fever)
valvular lesions (bacterial endocarditis)

63
Q

disorders of the conducting system

A

injuries to the AV bundle which is already vulnerable, cause disorders of the conducting system

*injuries result from myocarditis, chronic myocardial ischemia, MI, trauma from surgery and metastatic tumors

64
Q

what is the most frequent cardiac arrhythmia?

A

atrial fibrillation

65
Q

nerve fibers

A

axons enveloped in Schwann cells and can be small meaning they are unmyelinated (simple fold of a Schwann cell can cover many small axons) or thick meaning they are myelinated (Schwann cells wrap around multiple times squeezing out their cytoplasm)

66
Q

Schmidt-Lanterman cleft

A

the remaining cytoplasm when Schwann cells wrap around thicker axons multiple time and squeeze it out

67
Q

node of Ranvier

A

adjacent Schwann cells that are covered by cytoplasmic processes

68
Q

mesaxon

A

folds inward to accommodate an axon thus becomes a protective sheath

69
Q

nerves

A

bundles to nerve fibers that contain unmyelinated and myelinated axons and both motor and sensory fibers surrounded by CT

70
Q

layers of nerves

A

epinerium: outer coat of dense to loos CT
perineurium: forms a fascicle of axons and is made up of several layers of specialized fibroblastic cells (epithelioid myofibroblasts) that form tight junctions serving as a barrier to macromolecules protecting the microenvironment
endoneurium: delicate layer of reticular cells

71
Q

ganglia

A

clusters of neuron cell bodies that area surrounded by satellite cells (ex: sensory and autonomic ganglia)

72
Q

sensory ganglia

A

contain the cell bodies of pseudounipolar sensory neurons, have a centrally located nucleus and numerous myelinated nerve fibers but no synapses take place within the ganglion and satellite cells are evenly spaced and continuous providing a protective capsule

73
Q

autonomic ganglia

A

contain the cell bodies of multipolar neurons, have acentric nuclei, multiple dendrites and a single axon and synapses occur

*more disordered than sensory ganglia with multiple processes, smaller neuronal cell bodies and numerous unmyelinated nerve fibers

74
Q

termini

A

motor neurons have axons that project from the spinal cord to a motor end plate and the axon terminus has numerous synaptic vesicles

75
Q

what does the postsynaptic membrane of the skeletal muscle contain?

A

junctional folds and ACh reveptors

76
Q

receptors that initiate a nerve impulse in response to a stimulus

A

exteroreceptors, enteroreceptors and proprioreceptors

77
Q

free endings

A

bare axons important for the sensations from the skin of hot and cold, itching, touch and pain

78
Q

encapsulated endings

A

Meissner’s corpuscles- touch receptors that respond to low-frequency stimuli

Pacinian corpuscles- large endings made up of flattened Schwann cells which are mechanoreceptors that respond to pressure and vibration due to the displacement of capsule lamellae

Muscle spindles- proprioreceptors with thin specialized muscle fibers called intrafusal fibers in a fluid-filled space which send information to the spinal cord to play a role in reflexes involved in maintaining posture and coordinating walking

79
Q

primary function of blood vessels

A

to allow for the exchange of gases, maintain quality and quantity of tissue fluid and carry nutrients to waste, metabolic wastes away and hormones and signaling substances

80
Q

changes that occur in blood vessels with age

A

structural: largest arteries grow until age 25, media becomes stiffer after age 30 due to increase in elastic lamellae and deposition of collagen and proteoglycans

pathophysiological: ELASTIC ARTERIES–>there is a greater change in large elastic arteries than muscular arteries, elastic tissue in the media can develop irregular thickenings and elastic fibers can fragment, atherosclerotic plaques form in the intima due to lipid accumulation
MUSCULAR ARTERIES–> undergo calcification and develop atherosclerotic plaques in which the luminal diameter is greatly reduced

81
Q

lymphatic vascular system

A

parallels the blood capillaries but carries the lymph in one direction towards the large veins of the neck

*lymph= excess tissue fluid, cellular debris and lymphocytes

82
Q

conducting arteries

A

(large); rapid blood flow; pressure differences are smoothened out by elastic laminae

83
Q

distributing arteries

A

(medium); slow blood flow which is controlled by regulatory factors

84
Q

3 layers of blood vessels

A

there are 3 concentric layers or tunics surrounding their lumens: tunica intima, tunica media and tunica adventitia

85
Q

endocardium

A

intima that lines the atria and ventricles composed of an endothelium and subendothelium layer of CT

86
Q

myocardium

A

media that is the thickest layer of the heart and is composed of cardiac muscle that is thicker in the ventricles than in the atria

87
Q

epicardium

A

adventitia that forms the surface and defined as the visceral layer of the pericardium and is composed of a mesothelium and the subepicardial layer of the CT that contains nerves, adipose tissue and the coronary blood vessels

88
Q

what happens to vessels during systole and diastole

A

systole- distends elastic arteries

diastole- recoils and contracts

89
Q

large, elastic conducting arteries

A

elastic properties are seen in aorta, common carotid, brachicephalic, subclavian and pulmonary arteries

intima- contains Weibel-Palade bodies and elongated endothelial cells with long axes oriented with blood flow
media- elastic lamellae with smooth muscle cells with a thin external elastic lamina and penetrating vaso vasorum from the adventitia
adventitia- thin with nerve fibers, lymphatics and vasa vasorum in the loose CT

90
Q

mixed, musculo-elastic arteries

A

transitional segments between large and medium arteries seen in terminal abdominal aorta, iliac arteries, external carotids, axillary arteries

  • media and adventitia are about the same thickness
  • media has fewer elastic lamellae
91
Q

arterioles

A

functions to reduce BP especially in capillaries, is invisible to the naked eye

intima- thin subendothelial layer of reticular fibers
media- 1-5 layers of smooth muscle
adventitia- moderate

92
Q

medium, muscular, distributing arteries

A

distribute blood to tissues and organs regulated by the ANS including coronary, renal, mesenteric, brachial femoral etc.

intima- thin with internal elastic lamina
media- thick and has many layers of smooth muscle bounded by external elastic lamina
adventitia- thick with poorly developed vasa vasorum and lymphatics

93
Q

capillaries

A

smallest vascular channels with a diameter of approximately 5-10 microns and is made up of endothelial cells and surrounded by pericytes

94
Q

endothelial cells

A

cytoplasm has Golgi complex, mitochondria, RER and free ribosomes, is supported by intermediate filaments (desmin and vimentin) and joined by tight and gap junctions

*life span of 150-180 days and synthesizes bioactive substances such as types I, III, IV and V collagens, fibronectin, laminin, coagulants and anticoagulants

95
Q

pericytes

A

stellate cells that surround capillaries with extensive branching processes, large nuclei, heterochromatin, small Golgi mitochondria, RER and filaments sharing the basal lamina with endothelial cells and serve as stem cells for endothelial and smooth muscle cells after injury

96
Q

3 types of capillaries

A

continuous

fenestrated

sinusoids

97
Q

continuous capillaries

A

most common; found in muscle, nervous and CT and the exocrine pancreas with complete basal lamina permitting passage of small molecules due to tight junctions and its cytoplasm has many vesicles that aid in transportation of large molecules

98
Q

fenestrated capillaries

A

found in the pancreas, intestines and endocrine glands with a continuous (but thin) endothelium and basal lamina with small pores/fenestrae specialized for rapid interchange of substances between blood and tissue

99
Q

sinusoid capillaries

A

irregular blood channels that conform to shapes and are available in three types (sinusoidal- endocrine glands; discontinuous- liver and bone marrow; venous- spleen) with discontinuous sinusoids having discontinuous or absent basal lamina with gaps that permit enhanced exchange between blood and tissue

100
Q

methods of transport across capillary endothelial cells

A

pinocytotic vesicles
trans-Golgi network vesicles
transient fenestrations

101
Q

capillary permeability systems

A

two distinct pore systems

  1. small: gaps between cell junctions allowing water and small hydrophilic molecules to pass
  2. large: transcytosis by pinocytotic or trans-Golgi derived vesicles
102
Q

what is different about veins compared to arteries

A
  • greater variation in size and structure
  • larger caliber
  • more numerous
  • extensive vasa vasorum and lymphatics
  • more collagen
  • less elastic substance and smooth muscle
  • thick due to adventitia
  • small and medium veins have valves that are formed from an infolding of the intima with an elastic CT core
103
Q

large veins intima, media and adventitia

A

intima: continuous endothelium and basal lamina, no internal elastic lamina
media: incomplete/absent
adventitia: largest, thick bundles of longitudinally oriented smooth muscle and collagen and elastic fibers, well developed vasa vasorum and lymphatics

104
Q

small and medium veins intima, media and adventitia

A

intima: continuous endothelium and basal lamina; complete internal elastic laminae and some valves
media: poorly developed except in limbs
adventitia: thick and has no smooth muscle but contains collagen, elastic fibers, fibroblasts, lymphatics and vasa vasorum

105
Q

two classes of venules and their functions

A

*continue material exchange and preferred location of leukocyte emigration becoming leaky in response to histamine and serotonin

pericytic venules: 10-50 microns in diameter resembling large capillaries
muscular venules: receive blood from pericytic venules and arterioles; the media has 1-2 circular layers of smooth muscle cells with a thin adventitia of loose CT

106
Q

portal systems

A

carry blood from one capillary bed to another

107
Q

arteriovenous anastomoses

A

direct cross connections between arterioles and venules in which smooth muscle cells form a sphinchter that regulates blood flow and allows a bypass of a capillary bed

108
Q

lymphatic vessels

A

have large lumens, thin walls, irregular shapes, extensive branching that runs parallel to blood capillaries and veins and function to collect lymph from extracellular spaces and return it to the blood vascular system and aid in the circulation of lymphocytes

  • similar to veins but more irregular in shape
  • have a discontinuous or absent basal lamina and are held open by elastic anchoring filaments
109
Q

3 types of cartilage

A

hyaline
elastic
fibrocartilage

110
Q

what is the function of cartilage and what is it made of?

A

provides support of soft tissues and forms articular surfaces of bone helping it to grow in length

made up of chondrocyte cells located in lacunae and extracellular matrix

111
Q

chondrocytes

A

made up of proteoglycan aggregates (which resist deformation) and type II collagen (which aids in shape and strength forming a fibrillar scaffold) with a chromatin filled nucleus, prominent nucleolus, cytoplasm with RER, developed Golgi apparatus and mitochondria

*proteoglycans are made up of glycosaminoglycans (chondroitin sulfate 4 and 6 and keratin sulfate) bound to hyaluronic acid

112
Q

peridchondrium

A

made up of two layers: outer fibrous (type I collagen and fibroblasts) and inner chondrogenic (cellular with chrondroblasts)

113
Q

describe the growth of cartilage

A

chrondroblasts undergo mitosis and differentiate into chondrocytes which produce extracellular matrix and clusters of cells called isogenous groups that end up in lacunae

114
Q

hyaline cartilage

A

most common appearing in the ventral ends of ribs, tracheal rings, larynx, bronchi, joints and nose with an extracellular matrix that is basophilic with a capsular matrix, interterritorial matrix and type II collagen

*subject to degeneration

115
Q

elastic cartilage

A

located where flexible support is needed such as the external ear, epiglottis and Eustachian tube and contains an extracellular matrix that is flexible and less homogeneous than hyaline cartilage

  • stains with orcein dyes
  • less susceptible to degeneration
116
Q

fibrocartilage

A

located in tendons, joints and have chondrocytes that are similar to hyaline and elastic cartilage with a extracellular matrix that is reduced in ground substance

  • increased amount of type I collagen that causes matrix to be eosinophilic
  • it is the transition between hyaline and dense regular CT
117
Q

calcification of matrix

A

process that occurs as you age in which the hyaline cartilage is the most susceptible

118
Q

osteoarthritis

A

loss or change in articular cartilage that occurs as a result of the aging process

119
Q

chondroma

A

benign tumors of cartilage

120
Q

chondrosarcoma

A

malignant tumors of cartilage that are slow growing

121
Q

spongy bone

A

cancellous (mesh)–> 3D lattice of branching trabeculae filled with bone marrow and lined by endosteum

  • intercellular substance is lammelar with no lamellar patterns like in compact bone
  • osteocytes are identical to those of compact bone and seen in H&E sections
122
Q

compact bone

A

cortical–> more solid with spaces only seen under a microscope

*composed mainly of extracellular matrix and has lamella collagen fibers that are parallel to each other and perpendicular to those in adjacent lamellae

123
Q

bone

A

vascularized modified CT made up of osteocytes in lacunae and covered in periosteum that provides support and protects organs while housing bone marrow, nerves and specific minerals

  • extracellular matrix normally becomes calcified
  • can grow by appositional growth but NOT interstitial growth
  • calcification of the ECM is a normal process
124
Q

endosteum

A

specialized CT with osteogenic potential that lines the inner surfaces of bone

125
Q

canaliculi

A

tubular channels that radiate from lacunae with gap junctions in between (for ions and small molecules to pass) and contain filopodial processes from osteocytes

126
Q

3 lamellar patterns of compact bone

A
  • concentrically arranged around vascular channels
  • outer and inner circumferential lamellae
  • interstitial (intermediate) systems)
127
Q

Haversian canals -(compact bone)

A

cylindrical units called osteons which contain vessels, loose CT and nerves that run parallel to bone which are connected by Volkman’s canals that run at oblique angles and aren’t completely surrounded by concentric lamellae

128
Q

outer and inner circumferential lamellae -(compact bone)

A

consists of few lamellae that extends around circumference of shaft and is located beneath periosteum and below endosteum

129
Q

interstitial (intermediate) systems -(compact bone)

A

angular fragments of lamellar bone located between Haversian systems

130
Q

what is the ECM of compact bone made of?

A

organic osteoid (with a ground substance made of proteoglycans with a lesser degree of sulfation than cartilage and a matrix that is acidophilic with noncollagenous proteins responsible for the toughness and resilience of bone) and inorganic salts (thin plates of Ca2+P/hydroxyapatite associated with collagen fibers and responsible for the hardness of bone)

131
Q

endosteum

A

delicate, single layer, lines vascular channels and covers the trabeculae of spongy bone

132
Q

periosteum

A

outer fibrous layer (dense irregular tissue with few fibroblasts and blood vessles that enter Volkman’s canals with collagn fibers that anchor periosteum to bone) and deep cellular layer (with osteogenic potential whose appearance depends on functional state containing osteoblasts during growth and osteoprogenitor cells in adulthood)

133
Q

osteoprogenitor cells

A

it not actively making bone and is composed of compact chromatin with less basophilic cytoplasm than osteoblast that can be reactivated

134
Q

Sharpey’s fibers

A

collagen fibers of the outer fibrous layer of the periosteum of compact bone that anchor periosteum to bone

135
Q

remodeling of bone

A

begins immediately involving activity of osteoblasts and osteoclasts (mechanotransducers of local strain located on Howship’s lacunae or resorption bays) to provide maximal strength with minimum bone mass

  • spongy is more responsive to changes
  • compact- Haversian systems are formed/resorbed/replaces constantly
136
Q

cathepsins

A

lysosomal hydrolytic enzymes used by osteocytes to break down organic matrix creating an acid environment (sealing zone) through a proton pump for dissolution of bone mineral

137
Q

fate of degraded bone proteins and inorganic matrix components

A

taken up by osteoclasts through endocytosis and transcytosed in vesicles through the cytoplasm then released through the free surface of the osteoclast

138
Q

osteoporosis and treatment

A

more resorption compared to formation due to enhanced osteoclast activity from falling estrogen levels at menopause

  • treatment- bisphosphonates which reduces osteoclast formation/function/survival but prolonged use can lead to osteonecrosis (reduced blood flow to joints especially the jaw)
  • common in men >50 and females in menopause
139
Q

osteopetrosis

A

defective osteoclasts will cause bone formation to exceed absorption leading to dense/heavy bones

140
Q

osteogenesis imperfecta

A

osteoblasts do not produce enough type I collagen leading to bone fragility

141
Q

rickets

A

failure to produce vitamin D prevents calcification of bone matrix leading to softening bones

142
Q

purpose of cartilage and bone

A

to support CT

143
Q

increase of hyaline cartilage mass

A

external addition and internal addition of mass

144
Q

diaphysis and epiphysis of bone

A

diaphysis- cylindrical part that has a thick outer layer of compact bone with a thin marrow cavity containing spongy bone

epiphysis- bulbous ends made of spongy bone covered by a thin layer of compact bone

145
Q

lamellae

A

defined layers of the ECM of bone containing collagen fibers

146
Q

lacunae

A

small cavities that are spaced uniformly throughout the ECM containing osteocytes and radiating canaliculi channels

147
Q

functional adaptation

A

providing maximal strength with minimum bone mass while removing microdamage to replace with new bone

148
Q

how are trabeculae distributed in spongy bone?

A

aligned following lines of stress to which the bone was subjected

149
Q

morphology of osteoclasts

A

large multinucleated cells with eosinophilic cytoplasm, mitochondria and lysosomes and a ruffled border

*attached to bone by podosomes that form a tight seal