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Flashcards in 1a1-chapter 5 Histology Deck (173):
1

four broad categories of tissues

–epithelial tissue
–connective tissue
–nervous tissue
–muscular tissue

2

organ

structure with discrete boundaries that is composed of two or more tissue types

3

histology

(microscopic anatomy) –the study of tissues and how they are arranged into organs

4

tissue

a group of similar cells and cell products that arise from the same region of the embryo and work together to perform a specific structural or physiological role in an organ.

5

four primary tissues differ from one another in the:

–types and functions of their cells
–the characteristics of the matrix (extracellular material)
–the relative amount of space occupied by cells versus matrix

6

matrix–(extracellular material) is composed of :

–fibrous proteins
–a clear gel known as ground substance , tissue fluid, extracellular fluid (ECF), interstitial fluid, or tissue gel

7

Embryonic Tissues

human development begins as single cell the fertilized egg
–divides to produce scores of identical, smaller cells
–first tissues appear when these cells start to organize themselves into layers
•first two, and then three strata

8

3 primary germ layers

–ectoderm
-endoderm
–mesoderm

9

–ectoderm

(outer)
•gives rise to epidermis and nervous system

10

endoderm

(inner)
•gives rise to mucous membrane lining digestive and respiratory tracts, digestive glands, and among other things

11

mesoderm

(middle) becomes gelatinous tissue -mesenchyme
•wispy collagen fibers and fibroblasts in gel matrix
•gives rise to muscle, bone, blood

12

preparation of histological specimens

fixative
histological sections
stains

13

fixative

prevents decay (formalin)

14

histological sections

tissue is sliced into thin sections one or two cells thick

15

stains

tissue is mounted on slides and artificially colored with histological stain
•stains bind to different cellular components

16

Sectioning

reduces three-dimensional structure to two-dimensional slice

17

Sectioning Solid Objects

•sectioning a cell with a centrally located nucleus
•some slices miss the cell nucleus
•in some the nucleus is smaller

18

Sectioning Hollow Structures

•cross section
•longitudinal section
oblique section

19

Types of Tissue Sections

longitudinal section
cross section or transverse section

20

longitudinal section

tissue cut along long direction of organ

21

cross section or transverse section

tissue cut perpendicular to length of organ

22

oblique section

tissue cut at angle between cross and longitudinal section

23

Nonsectioned Preparation

•Smear –tissue is rubbed or spread across the slide
–spinal cord or blood
•Spread –cobwebby tissue is laid out on a slide
–areolar tissue

24

Epithelial Tissue

•consists of a flat sheet of closely adhering cells
•one or more cells thick
•upper surface usually exposed to the environment or an internal space in the body
•covers body surface
•lines body cavities
•forms the external and internal linings of many organs
•constitutes most glands
•extracellular material is so thin it is not visible with a light microscope
•epithelia allows no room for blood vessels
•lie on a layer of loose connective tissue and depend on its blood vessels for nourishment and waste removal

25

Basement Membrane

layer between an epithelium and the underlying connective tissue
•anchors the epithelium to the connective tissue below it

26

basement membrane contains:

–collagen
–laminin and fibronectin adhesive glycoproteins
–heparin sulfate -large protein-carbohydrate complex

27

basal surface

surface of an epithelial cell that faces the basement membrane

28

apical surface

surface of an epithelial cell that faces away from the basement membrane

29

Simple epithelium

–contains one layer of cells
–named by shape of cells
–all cells touch the basement membrane

30

Stratified epithelium

–contains more than one layer
–named by shape of apical cells
–some cells rest on top of others and do not touch basement membrane

31

Simple Epithelia

4 types

–simple squamous (thin scaly cells)
–simple cuboidal (square or round cells)
–simple columnar (tall narrow cells)
–pseudostratified columnar

32

Simple Epithelia

three named for their cell shapes

–simple squamous (thin scaly cells)
–simple cuboidal (square or round cells)
–simple columnar (tall narrow cells)

33

Simple Epithelia

4th type

–pseudostratified columnar
•not all cells reach the free surface
•shorter cells are covered over by taller ones
•looks stratified
•every cell reaches the basement membrane

34

goblet cells

wineglass-shaped mucus secreting cells in simple columnar and pseudostratified epithelia

35

Simple Squamous Epithelium

•single row of thin cells
•permits rapid diffusion or transport of substances
•secretes serous fluid
•alveoli, glomeruli, endothelium, and serosa

36

Simple Cuboidal Epithelium

•single layer of square or round cells
•absorption and secretion, mucus production and movement
•liver, thyroid, mammary and salivary glands, bronchioles, and kidney tubules

37

Simple Columnar Epithelium

•single row tall, narrow cells
–oval nuclei in basal half of cell
–brush border of microvilli, ciliated in some organs, may possess goblet cells
•absorption and secretion; mucus secretion
•lining of GI tract, uterus, kidney and uterine tubes

38

18Pseudostratified Epithelium

•looks multilayered; some not reaching free surface; all touch basement membrane
–nuclei at several layers
–with cilia and goblet cells
•secretes and propels mucus
•respiratory tract and portions of male urethra

39

Stratified Epithelia

•range from 2 to 20 or more layers of cells
•some cells resting directly on others
•only the deepest layer attaches to the basement membrane
•most widespread epithelium in the body

40

Stratified Epithelia

4 types

–stratified squamous
–stratified cuboidal
–stratified columnar (rare)
–transitional epithelium

41

three stratified epithelia are named for the shapes of their surface cells

–stratified squamous
–stratified cuboidal
–stratified columnar (rare)

42

Stratified Epithelia

fourth type

–transitional epithelium

43

Stratified Epithelia


deepest layers undergo continuous

mitosis
–their daughter cells push toward the surface and become flatter as they migrate farther upward
–finally die and flake off –exfoliation or desquamation

44

two kinds of stratified squamous epithelia

–keratinized–found on skin surface, abrasion resistant
–nonkeratinized –lacks surface layer of dead cells

45

Keratinized Stratified Squamous

•multiple cell layers with cells becoming flat and scaly toward surface
•epidermis; palms and soles heavily keratinized
•resists abrasion; retards water loss through skin; resists penetration by pathogenic organisms

46

Nonkeratinized Stratified Squamous

•same as keratinized epithelium without the surface layer of dead cells
•tongue, oral mucosa, esophagus and vagina
•resists abrasion and penetration of pathogens

47

Stratified Cuboidal Epithelium

•two or more cell layers; surface cells square or round
•secretes sweat; sperm production and produces ovarian hormones
•sweat gland ducts; ovarian follicles and seminiferoustubules

48

Transitional Epithelium

•multilayered epithelium surface cells that change from round to flat when stretched
•allows for filling of urinary tract
•ureter and bladder

49

connective tissue

a type of tissue in which cells usually occupy less space than the extracellular material
•most cells of connective tissue are not in direct contact with each other
•highly vascular –richly supplied with blood vessels
•most abundant, widely distributed, and histologically variable of the primary tissues

50

connective tissue

function

•binding of organs –tendons and ligaments
•support –bones and cartilage
•physical protection –cranium, ribs, sternum
•immune protection –white blood cells attack foreign invaders
•movement–bones provide lever system
•storage–fat, calcium, phosphorus
•heat production –metabolism of brown fat in infants
•transport-blood

51

Components of Fibrous Connective Tissue

-cells
-fibers
-ground substance

52

Components of Fibrous Connective Tissue

cells

6

–fibroblasts
–macrophages
–leukocytes
–plasma cells
–mast cells
–adipocytes

53

fibroblasts

produce fibers and ground substance

54

macrophages

phagocytose foreign material and activate immune system when sense foreign matter (antigen)
•arise from white blood cell -monocytes

55

leukocytes

white blood cells

56

plasma cells

synthesize disease fighting antibodies

57

mast cells

found along side of blood vessels

58

adipocytes

store triglycerides (fat molecules)

59

Components of Fibrous Connective Tissue

fibers
3

collagenous fibers
reticular fibers
elastic fibers

60

collagenous fibers

•most abundant of the body‟s proteins –25%
•tough, flexible, and resist stretching
•tendons, ligaments, and deep layer of the skin are mostly collagen
•less visible in matrix of cartilage and bone

61

reticular fibers

•thin collagen fibers coated with glycoprotein
•form framework of such organs as spleen and lymph nodes

62

elastic fibers

•thinner than collagenous fibers
•branch and rejoin each other
•made of protein called elastin
•allows stretch and recoil
•yellow fibers–fresh elastic fibers

63

Components of Fibrous Connective Tissue

ground substance
3

usually a gelatinous to rubbery consistency resulting from three classes of large molecules
-glycosaminoglycans (GAG)
- proteoglycan
-adhesive glycoproteins

64

glycosaminoglycans (GAG)

•long polysaccharide composed of unusual disaccharides called amino sugars and uronic acid
•play important role of regulating water and electrolyte balance in the tissues

65

glycosaminoglycans (GAG)

2 types

chondroitin sulfate
hyaluronic acid

66

chondroitin sulfate

most abundant GAG
–in blood vessels and bone
–responsible for stiffness of cartilage

67

hyaluronic acid

viscous, slippery substance that forms an effective lubricant in joints and constitutes much of the vitreous body of the eyebal

68

proteoglycan

•gigantic molecule shaped like a test-tube brush
•forms thick colloids that creates strong structural bond between cells and extracellular macromolecules –holds tissues together

69

adhesive glycoproteins

bind components of tissues together

70

Types of Fibrous Connective Tissue

loose connective tissue
dense connective tissue

71

loose connective tissue

–much gel-like ground substance between cells
–types
•areolar
•reticular

72

Areolar Tissue

•loosely organized fibers, abundant blood vessels, and a lot of seemingly empty space
•possess all six cell types
•fibers run in random directions
–mostly collagenous, but elastic and reticular also present
•found in tissue sections from almost every part of the body
•nearly every epithelium rests on a layer of areolar tissue

73

Reticular Tissue

•mesh of reticular fibers and fibroblasts
•forms supportive stroma (framework) for lymphatic organs
•found in lymph nodes, spleen, thymus and bone marrow

74

dense connective tissue

–fibers fill spaces between cells
–types vary in fiber orientation
•dense regular connective tissue
•dense irregular connective tissue

75

Dense Regular Connective Tissue

•densely, packed, parallel collagen fibers
–compressed fibroblast nuclei
•tendons attach muscles to bones and ligaments hold bones together

76

Dense Irregular Connective Tissue

densely packed, randomly arranged, collagen fibers and few visible cells
–withstands unpredictable stresses
–deeper layer of skin; capsules around organs

77

adipose tissue

(fat) –tissue in which adipocytesare the dominant cell type
•space between adipocytes is occupied by areolar tissue, reticular tissue, and blood capillaries
•fat is the body‟s primary energy reservoir
•the quantity of stored triglyceride and the number of adipocytes are quite stable in a person
–fat is recycled continuously to prevent stagnation
–new triglycerides are constantly synthesized and stored
–old triglycerides are hydrolyzed and released into circulation
•provides thermal insulation
•anchors and cushions organs such as eyeball, kidneys
•contributes to body contours –female breast and hips
•on average, women have more fat than men
•too little fat can reduce female fertility
•most adult fat is called white fat
•brown fat –in fetuses, infants, children –a heat generating tissue

78

Adipose Tissue

•empty-looking cells with thin margins; nucleus pressed against cell membrane
•energy storage, insulation, cushioning
–subcutaneous fat and organ packing
–brown fat (hibernating animals) produces heat

79

Cartilage

•supportive connective tissue with flexible, rubbery matrix
•gives shape to ear, tip of nose, and larynx
•No blood vessels
–diffusion brings nutrients and removes wastes
–heals slowly
•matrix rich in chondroitin sulfate and contain collagen fibers

80

chondroblasts

produce matrix and surround themselves until they become trapped in little cavities (lacunae)

81

chondrocytes

cartilage cells in lacunae

82

perichondrium

sheath of dense irregular connective tissue that surrounds elastic and most hyaline cartilage (not articular cartilage)
–contains a reserve population of chondroblasts that contribute to cartilage growth throughout life

83

types of cartilage

3

vary with fiber types
–hyaline cartilage, fibrocartilage and elastic cartilage

84

Hyaline Cartilage

•clear, glassy microscopic appearance because of unusual fineness of the collagen fibers
•usually covered by perichondrium
•articular cartilage, costal cartilage, trachea, larynx, fetal skeleton
•eases joint movement, holds airway open, moves vocal cords during speech

85

Elastic Cartilage

• cartilage containing elastic fibers
• covered with perichondrium
• provides flexible, elastic support
– external ear and epiglottis

86

Fibrocartilage

• cartilage containing large, coarse bundles of collagen fibers
• never has perichondrium
• resists compression and absorbs shock
– pubic symphysis, menisci, and intervertebral discs

87

"bone‟ has two meanings:

–an organ of the body; femur, mandible; composed of multiple tissue types
–bone tissue –osseous tissue –makes up most of the mass of bone

88

two forms of osseous tissue

spongy bone
compact bone

89

spongy bone

spongy in appearance
•delicate struts of bone -trabeculae
•covered by compact bone
•found in heads of long bones and in middle of flat bones such as the sternum

90

compact bone

compact bone –denser calcified tissue with no visible spaces
•more complex arrangement
•cells and matrix surround vertically oriented blood vessels in long bones

91

Bone Tissue (compact bone)

most compact bone is arranged in cylinders that surround central (haversian or
osteonic) canals that run longitudinally through shafts of long bones
– blood vessels and nerves travel through central canal

92

bone matrix deposited in

concentric lamella
– onionlike layers around each central canal

93

osteon

central canal and its surrounding lamellae

94

osteocytes

mature bone cells that occupy the lacunae

95

canaliculi

delicate canals that radiate from each lacuna to its neighbors, and
allows osteocytes to contact each other

96

periosteum

tough fibrous connective tissue covering of the bone as a whole

97

Blood

fluid connective tissue
•transports cells and dissolved matter from place to place

98

plasma

blood‟s liquid ground substance

99

formed elements

cells and cell fragments
–erythrocytes
–leukocytes
–platelets

100

erythrocytes

red blood cells –transport O2 and CO2

101

leukocytes

white blood cells –defense against infection and other diseases

102

platelets

cell fragments involved in clotting and other mechanisms

103

Excitable Tissues

Muscular & Nervous Tissue

104

excitability

a characteristic of all living cells
–developed to highest degree in nervous and muscular tissues

105

membrane potential

electrical charge difference (voltage) that occurs across the plasma membranes is the basis for their excitation
–respond quickly to outside stimulus by means of changes in membrane potential
–nerves–changes result in rapid transmission of signals to other cells
–muscles–changes result in contraction, shortening of the cell

106

Nervous Tissue

specialized for communication by electrical and chemical signals

107

Nervous Tissue consists of

neurons (nerve cells)
neuroglia (glial)

108

neurons

–detect stimuli
–respond quickly
–transmit coded information rapidly to other cells

109

neuron parts

neurosoma (cell body)
dendrites
axon (nerve fiber)

110

neurosoma

(cell body)
•houses nucleus and other organelles
•cell‟s center of genetic control and protein synthesis

111

dendrites

•multiple short, branched processes
•receive signals from other cells
•transmit messages to neurosoma

112

axon

(nerve fiber)
•sends outgoing signals to other cells
•can be more than a meter long

113

neuroglia

(glial)
–protect and assist neurons
–„housekeepers‟ of nervous system

114

Muscular Tissue

elongated cells that are specialized to contract in response to stimulation
•primary job is to exert physical force on other tissues and organs
•creates movements involved in body and limb movement, digestion, waste elimination, breathing, speech, and blood circulation
•important source of body heat

115

three types of muscle:

skeletal, cardiac, and smooth

116

Skeletal Muscle

long, threadlike cells –muscle fibers
•most attach to bone
•contains multiple nuclei adjacent to plasma membrane
•striations –alternating dark and light bands
•voluntary–conscious control over skeletal muscles

117

sphincter muscles

ringlike or cufflike muscles that open and close body passages

118

48Cardiac Muscle

•limited to the heart
•myocytesor cardiocytesare much shorter, branched, and notched at ends
•contain one centrally located nucleus surrounded by light staining glycogen
•intercalated discs join cardiocytes end to end
–provide electrical and mechanical connection
•striated, and involuntary (not under conscious control)

119

Smooth Muscle

•lacks striations and is involuntary
•relatively short, fusiform cells (thick in middle, tapered at ends)
•one centrally located nucleus
•visceral muscle
•propels contents through an organ, regulates diameter of blood vessels

120

visceral muscle

forms layers of digestive, respiratory, and urinary tract: blood vessels, uterus and other viscera

121

intercellular junctions

connections between one cell and another
•all cells (except blood and metastatic cancer cells) are anchored to each other or their matrix by intercellular junctions
•resist stress and communicate with each other

122

intercellular junctions

Tight Junctions
Desmosomes
Gap Junctions

123

51Tight Junctions

a region in which adjacent cells are bound together by fusion of the outer phospholipid layer of their plasma membranes.
–in epithelia, forms a zone that completely encircles each cell near its apical pole
–seals off intercellular space
–makes it impossible for something to pass between cells

124

Desmosomes

patch that holds cells together (like a clothing snap)
•serves to keep cells from pulling apart –resists mechanical stress
•hooklike J-shaped proteins arise from cytoskeleton
–approach cells surface
–penetrate into thick protein plaques linked to transmembrane proteins

125

hemidesmosomes

anchor the basal cells of epithelium to the underlying basement membrane
–epithelium can not easily peel away from underlying tissues

126

Gap Junctions

formed by a ringlike connexon
–consists of six transmembrane proteins arranged like segments of an orange
–surrounding a water-filled pores
–ions, glucose, amino acids and other solutes pass from one cell to the next

127

gland

cell or organ that secrete substances for use elsewhere in the body or releases them for elimination from the body
–composed of epithelial tissue in a connective tissue framework and capsule

128

exocrine glands

maintain their contact with the body surface by way of a duct(epithelial tube that conveys secretion to surface)
–sweat, mammary and tear glands

129

endocrine glands

lose their contact with the surface and have no ducts
–hormones–secretion of endocrine glands
–secrete (hormones) directly into blood
–thyroid, adrenal and pituitary glands

130

some organs have both endocrine and exocrine function

liver, gonads, pancreas

131

unicellular glands

found in epithelium that is predominantly nonsecretory
–can be endocrine or exocrine
–mucus-secreting goblet or endocrine cells of stomach and small intestine

132

Exocrine Gland Structure

capsule
stroma
parenchyma

133

capsule

connective covering of most glands
–septaor trabeculae –extensions of capsule that divide the interior of the gland into compartments (lobes)
–further divided into smaller lobules

134

stroma

connective tissue framework of the gland
–supports and organizes glandular tissue

135

parenchyma

the cells that perform the tasks of synthesis and secretion
–typically cuboidal or simple columnar epithelium

136

Types of Exocrine Glands

•simple-unbranched duct
•compound -branched duct
•shape of gland

137

shape of gland

–tubular –duct and secretory portion have uniform diameter
–acinar -secretory cells form dilated sac (acinus or alveolus)
–tubuloacinar -both tubular and acinar portions

138

serous glands

produce thin, watery secretions
•perspiration, milk, tears and digestive juices

139

mucous glands

–produce glycoprotein, mucin,that absorbs water to form a sticky secretion called mucus
–goblet cells –unicellular mucous glands

140

mixed glands

contain both cell types and produce a mixture of the two types of secretions

141

cytogenic glands

release whole cells, sperm and egg cells

142

Merocrine Gland

(eccrine glands) –have vesicles that release their secretion by exocytosis
–tear glands, pancreas, gastric glands, and others

143

apocrine glands

primarily merocrine mode of secretion
–axillary sweat glands, mammary glands

144

holocrine glands

cells accumulate a product and then the entire cell disintegrates
–secretion a mixture of cell fragments and synthesized substance
–oil glands of scalp, glands of eyelids

145

membranes

line body cavities and cover their viscera

146

cutaneous membrane

the skin –largest membrane in the body
–stratified squamous epithelium (epidermis) over connective tissue (dermis)
–relatively dry layer serves protective function

147

mucous membrane (mucosa)

lines passageways open to the external environment

148

serous membrane (serosa)

internal membrane
–simple squamous epithelium over areolar tissue
–produces serous fluid that arises from blood
–covers organs and lines walls of body cavities

149

serous membrane

endothelium

endothelium lines blood vessels and heart

150

serous membrane

mesothelium

mesothelium line body cavities (pericardium, peritoneum and pleura)

151

synovial membrane

lines joint cavities
–connective tissue layer only, secretes synovial fluid

152

Mucous Membranes (Mucosa)

•lines passages that open to the external environment
–digestive, respiratory, urinary, and reproductive tracts
•absorptive, secretory, and protective functions
•covered with mucus

153

Mucous Membranes (Mucosa)

layers

•consists of two to three layers:
–epithelium
–lamina propria –areolar connective tissue
–muscularis mucosae –smooth muscle layer

154

tissue growth

increasing the number of cells or the existing cells grow larger

155

hyperplasia

tissue growth through cell multiplication

156

hypertrophy

enlargement of preexisting cells
–muscle grows through exercise
–accumulation of body fat

157

neoplasia

development of a tumor (neoplasm)
–benign or malignant
–composed of abnormal, nonfunctional tissue

158

Differentiation

unspecialized tissues of embryo become specialized mature types
•mesenchyme to muscle

159

Metaplasia

changing from one type of mature tissue to another

160

stem cells

undifferentiated cells that are not yet performing any specialized function
–have potential to differentiate into one or more types of mature functional cells

161

developmental plasticity

diversity of mature cell types to which stem cells can give rise

162

embryonic stem cells

totipotent
pluripotent

163

totipotent

have potential to develop into any type of fully differentiated human cell

164

pluripotent

can develop into any type of cell in the embryo
•source -cells of inner cell mass of embryo

165

adult stem cells

undifferentiated cells in tissues of adults
–multipotent -bone marrow producing several blood cell types
–unipotent–most limited plasticity -only epidermal cells produced

166

regeneration

replacement of dead or damaged cells by the same type of cell as before
–restores normal function
–skin injuries and liver regenerate

167

fibrosis

replacement of damaged cells with scar tissue
–holds organs together
–does not restore normal function

168

Wound Healing

-Bleeding into wound
-scab formation and macrophage activity
-formation of granulation tissue -fiboblast repair
-Epithelial regeneration and connective tissue fibrosis (remodeling phase of repair)

169

atrophy

shrinkage of a tissue through a loss in cell size or number
–senile atrophy through normal aging
–disuse atrophy from lack of use (astronauts)

170

necrosis

premature, pathological death of tissue due to trauma, toxins, or infections

171

apoptosis

programmed cell death

172

tissue engineering

artificial production of tissues and organs in the lab for implantation in the human body

173

skin grafts

already available