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Chapter 5-- Histology (microscopic anatomy)

Ch. 5 Study Guide 1. Read Chapter 5 up to page 170 right

before 5.4 Nervous and Muscular Tissue2. Comprehend Terminology (those in bold in

the textbook)3. Study-- Figure questions, Think About It

questions, and Before You Go On (section-ending) questions

4. Do end-of-chapter questions Testing Your Recall— 1-4, 6-10, 13, 17, 18, 20 True or False– 1, 2, 5, 6, 10 Testing Your Comprehension-- #4, #5

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5.1--The study of tissues

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§ The Study of Tissues1. Whole body contains only 200 different types

of cells2. Four tissue classes (Def. of tissue--?) See

Table 5.1.

3. Histology (microscopic anatomy)– study of tissues and how they form organs

4. Organ = structure with discrete boundaries– composed of 2 or more tissue types– Examples:

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§ Differences among 4 Tissue Classes

1. Types and functions of cells-- • For example: Epithelial, CT, Nervous,

Muscular2. Characteristics of the matrix

(extracellular material)• Rubbery, stony, or gelatinous

3. Relative amount of space occupied by cells versus matrix• CT vs. muscle and epithelium

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§ Embryonic Tissues1. Embryo begins as a single cell

– divides into many cells that form layers (strata)

2. Three primary germ layersA.ectoderm (outer) gives rise to: epidermis +

nervous system B.endoderm (inner): mucous membranes: GI

tract and respiratory linings; digestive glands. C.mesoderm (middle) forms mesenchyme

(gelatinuous tissue) and then give rise to muscle, bone, and blood

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§ Tissue Sectioning (1)

1. Preparation of histological specimens– fixation– sections– mounted on slides & stained

2. Sectioning (slicing) an organ or tissue reduces a 3-dimensional structure to a 2-dimensional slice (see the next 3 slides)

1 2 3 4 5

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4

5

•Slices 1 & 5 miss the yolk / cell nucleus

•Cell nucleus is smaller in sections 2 & 4

Tissue Sectioning (2)

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Tissue Sectioning (3)• Image A is a cross

section of elbow macaroni, resembling a blood vessel, piece of gut, or other tubular organ.

• Image B is a longitudinal section of a sweat gland. Notice what a single slice could look like

A B

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§ Types of Tissue Sections (1)• Longitudinal section

– tissue cut along the longest direction of an organ

• Cross section– tissue cut perpendicular

to the length of an organ

• Oblique section– tissue cut at an angle

between a cross & longitudinal section

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Types of Tissue Sections (2)

• Would you classify the egg sections as longitudinal, cross, or oblique sections?

• How would the egg look if sectioned in the other two planes? (Fig. 5.2 question)

Practice at home.

5.2--Epithelial tissue

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§ Epithelial Tissue Introduction (1)1. One or more layers of closely adhering cells

2. (Top) Forms a flat sheet with the upper (______) surface exposed to the environment or an internal body cavity

3. (Bottom) Sits on basement membrane (basal surface of cells); Fig. X– anchors epithelium to underlying connective tissue

4. (Nourishment) No room for blood vessels; . . .

CT

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What are the functions of the basement membrane?

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§ Epithelial Tissue Introduction (2)

Arrangement and Cell Shape—

1.Simple epithelium– contains one layer of cells– named by shape of cells

2.Stratified epithelium– contains more than one layer– named by shape of apical cells

Fig. 5.3

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§ 1.Simple Squamous Epithelium—

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1. (Structure) Single row of flat cells (scaly)

2. (Functions) Allows rapid diffusion of substances; secretes serous fluid

3. (Locations) in alveoli, glomerular capsule, endothelium (blood vessels and heart), and serosa (external surface) such as stomach & intestines

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§ 2. Simple Cuboidal Epithelium— 1. (Structure) Single row of cube-shaped cells,

often with microvilli

2. (Functions) Absorption & secretion; produces mucus

3. (Locations) Liver, thyroid, mammary, salivary and other glands, bronchioles, and most kidney tubules

Fig. 5.5

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§ 3.Simple Columnar Epithelium—

1. (Structure) Single row of tall, narrow cells

– vertically oriented, oval nuclei in basal half of cell

2. (Functions) Absorption & secretion; secretion of mucus

3. (Locations) Inner lining of GI tract from stomach to the anus; ducts of gallbladder; uterus, and uterine tubes; some kidney tubes; a few portions of upper respiratory tract

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§ 4. Pseudostratified Epithelium—

1. (Structure) Single row of cells not all of which reach the free surface; nuclei at different levels.

2. (Functions) secretes propels mucus

3. (Locations) most of the upper respiratory system from nasal cavity to bronchi; part of male urethra

Fig. 5.7

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§ Stratified Epithelia

• Composed of more than one layer of cells & named for shape of __________ cells

• Deepest cells sit on basement membrane

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§ 5A. Keratinized Stratified Squamous

• Layers of epithelium covered with compact, ______ squamous cells (no nuclei) packed with protein keratin

• Retards water loss, prevents entrance of organisms• Forms epidermal layer of skin (esp. soles and palms)

Fig. 5.8 S

kin

from

the sole of th

e foot

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§ 5B.Nonkeratinized Stratified Squamous

• Multilayered epithelium that lacks surface layer of dead cells forming moist, slippery layer

• Locations: tongue, oral mucosa, esophagus & vagina

Epithelial layer

Fig. 5.9 Mucosa of the vagina

Pap smear/test

• What? Examination of exfoliated cells

• Where? The cervix

• Why?

• How? Loose cells are examined microscopically for abnormal cells

• Who? Between 30-50 years old

Fig. 28.5

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Fig. 28.5—Pap smears

Which one is normal cells?

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§ 6. Stratified Cuboidal Epithelium

• (Structure) Two or more layers of cells; surface cells square or round

• (Functions) Secretion and production• (Locations) Sweat glands, mammary glands, salivary

glands, ovarian follicles, seminiferous tubules

Fig. 5.10—

Sw

eat glan

d d

ucts

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§ 7. Transitional Epithelium

1. (Structure) Multilayered epithelium with rounded (not flattened) surface cells

2. (Functions) Allow stretches and distension3. (Locations) Urinary tract--part of kidney,

ureter, urinary bladder, part of the urethra

Fig. X

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Qs from Before You Go On (p. 162)

Distinguish between simple and stratified epithelia. Explain why pseudostratified columnar epithelium belongs in the former category?Distinguish a stratified squamous epithelium from a transitional epithelium.How do the epithelia of the esophagus and stomach differ? Respective functions?

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5.3--Connective tissue

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§ Connective Tissue (CT) Overview

• Most abundant and variable tissue type

• 3 structural elements – – Consists mostly of (a) G________; (b) F_______ – (c) with widely spaced cells

• Functions of CT:– Binding of organs --Ex. a tendon connects

muscle to bone– Support, protection, movement -- Ex. bones– Storage – (energy, electrolytes) Ex. Fats/bones– Transport -- Ex. Blood

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§ 1. Ground Substance of C.T.

• Gelatinous or rubbery material found in between cells – Function?

• Consists of 3 classes of large molecules– Glycosaminoglycans (GAGs) –

• Polysacharides that attract sodium & hold water• Ex.--

– Proteoglycan is bottlebrush-shaped molecule • Forms thick gel that slows the spread of pathogens

– Cell adhesive glycoproteins• Allow themselves bind to matrix elements

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§ 2. Fibers of C.T.• Collagen fibers--called white fibers (Fig. 5.13)

– Most abundant protein of the body – Thick, tough, resist stretch yet flexible– Ex. tendons, ligaments & dermis

• Elastic fibers--called yellow fibers– made of E______; recoil like rubberband (elasticity)– Ex. skin, lungs & arteries; ability to recoil

• Reticular fibers– Thin collagen fibers coated with glycoprotein– Ex. form framework for spleen & lymph nodes

Figure 5.13

Tendons (collagen)

Collagen

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§ 3. Cells of C.T.• Fibroblasts -- produce fibers & ground substance• WBCs -- wander (mostly in CT) in search of

bacteria– Macrophages – large phagocytic cells-- arise from

monocytes (WBC); function? phagocytosis

– Plasma cells -- arise from lymphocytes; antibody-producing cells

• Mast cells – oval shaped; clustered along blood vessels; secrete heparin and histamine

• Adipocytes or fat cells --store triglycerides

5.3--Connective tissueA. Fibrous CT

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§ Five Types of Fibrous C.T.

Divided into 2 broad categories:

• Loose CT (3 slides followed)– contains MORE gel-like ground substance

between cells– 3 types: A--areolar, B--reticular, C--adipose tissue

• Dense CT (2 slides followed)– FIBERS fill the spaces between cells– 2 types varying in fiber orientation: D--dense

regular, E--dense irregular

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§ A-- Areolar Tissue

• Loose arrangement of collagenous and elastic fibers; scattered cell types; abundant ground substance

• Locations-- Underlying all epithelia; surrounding nerves, blood vessels, esophagus, trachea

Fig. Mesentery

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§ B-- Reticular Tissue• Loose network of

R_________ and cells

• Forms structural supportive stroma for lymphatic organs

• Locations-- lymph nodes, spleen, thymus & bone marrow Fig. Spleen

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§ C-- Adipose Tissue (Fat)• Large, empty-looking cells dominate with thin

margins; nucleus pressed against cell membrane; often very pale

• Functions-- Energy storage, insulation, space filled as cushioning

• Locations-- Subcutaneous fat beneath skin, breast, heart surface, surrounding organs

Fig. 5.18

Figure 5.16b

Fig. Adipose tissue

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§ D-- Dense Regular CT

• Structure-- Mainly densely, PACKED, PARALLEL C__________FIBERS; compressed fibroblast nuclei; scanty open space and blood vessels

• Locations-- Tendons & ligaments

Figure 5.16

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D-- Dense Regular CT

Fig. Tendon

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§ E-- Dense Irregular CT

• Densely packed collagen fibers running in ________ directions; scanty open space; few visible cells and blood vessels

• Function-- Withstands stresses applied in MANY DIFFERENT DIRECTIONS

• Locations-- Deeper portion of skin; capsules around organs (ex. Liver, kidney etc); sheaths around cartilages and bones

Figure 5.17

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E-- Dense Irregular CT

Fig. Dermis of the skin

5.3--Connective tissueB. Cartilage, Bone, Blood

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§ Cartilage• Supportive CT with rubbery matrix

• Chondroblasts produce matrix, surround themselves, and become Chondrocytes

• No blood vessels; so diffusion must bring in nutrients & remove wastes; healing . . .

• 3 types of cartilage depend upon FIBER TYPES

– A--hyaline, B--elastic, and C--fibrocartilage

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§ A-- Hyaline Cartilage• Clear, glassy matrix; invisible fine

dispersed collagen fibers; chondrocytes in small clusters enclosed in lacunae

• Supports airway, eases joint movements

• Locations-- Over ends of bones at movable joints; sternal ends of ribs; supportive material in larynx, trachea, bronchi and fetal skeleton

Fig. 5.19

Figure 5.19b

Fig. Fetal skeleton

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§ B-- Elastic Cartilage• Hyaline cartilage with weblike mesh of

elastic fibers amid the lacunae; always has perichondrium (a sheath of C.T.)

• Provides flexible, elastic support

• Locations— Ear + Epiglottis

• Fig. 5.20

Figure 5.20b

Fig. External ear

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§ C-- Fibrocartilage• Cartilage containing extensive parallel

Collagen fibers; never has perichondrium; row of chondrocytes in lacunae

• Resists compression and absorbs shock in some joints

• Locations-- Pubic symphysis, menisci (pads) in knee joint, & intervertebral discs

Fig. 5.21

Figure 5.21b

Fig. Intervertebral disc

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§ Bone (osseous tissue) • Spongy bone looks spongy in appearance

– fills heads of long bones

– delicate struts of bone

– ALWAYS COVERED BY COMPACT BONE

• Compact (dense) bone looks solid

– No space visible to the naked eye

– External surfaces of ALL bones

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§ Compact bone• Calcified matrix in concentric lamellae

around central (haversian) canal containing blood vessels

• osteocytes in lacunae between lamellae connected by canaliculi— delicate narrowing canals . . .

• Physical support; leverage for muscles; mineral storage

• Locations-- in skeleton (Fig. 5.22)

Fig. Compact bone60

Canaliculi ?

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§ Blood• Variety of cells and cell fragments;

some with nuclei & some without

• RBC, WBC, platelets

• Found in heart and blood vessels

Fig. 5.23

Fig. Blood smear62