Lab Activity 4 Classification of Tissues Martini Chapter

Lab Activity 4 Classification of Tissues Martini Chapter 4 Portland Community College BI 231

Tissues • Groups of cells similar in structure and function • • • Each tissue is then further subdivided into categories. All organs are made of a combination of different tissues. The four types of tissues • • Epithelial Connective Muscle Nerve 2

Epithelial Tissue Distinguishing Characteristics 1. 2. 3. 4. 5. Cellularity: Composed almost entirely of cells Polarity: apical and basal surfaces (top and a bottom) Attachment: Supported by connective tissue (basement membrane) Avascular: Contains no blood vessels: obtains nutrients by diffusion Regeneration: Rapidly replaces lost cells by cell division 3

Classification of Epithelia First name: 1. • • Simple: one layer Stratified: more than one layer Second name: 2. • Based on the shape of the top layer of cells • Squamous (flat) • Cuboidal (square) • Columnar (rectangle) Two additional categories 3. • • Transitional Pseudostratified 4

Classification of Epithelia 5

Classification of Epithelia • Squamous • Cuboidal • Columnar 6

Simple Squamous Epithelium • Single layer of flattened cells with discshaped nuclei and sparse cytoplasm 7

Simple Squamous Epithelium • Top View 8

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Simple Squamous Epithelium 10

Simple Squamous Epithelium • Functions: 1. Diffusion • Alveoli in the respiratory system allows for exchange of O 2 and CO 2 2. Filtration • Capillaries allow fluid and other substances out and holds blood cells and proteins in 3. Lubrication • Secretes lubricating substances in serosae 11

Simple Cuboidal Epithelium • Single layer of cube like cells with large, spherical central nuclei 12

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Simple Cuboidal Epithelium 14

Simple Cuboidal Epithelium • Functions: 1. Secretion • Glands such as the thyroid are composed of simple cuboidal epithelium and secrete hormones ect… 2. Absorption • In the kidney, the proximal convoluted tubule is composed of simple cuboidal epithelium and reabsorbs water and other nutrients from the filtered fluid 15

Simple Columnar Epithelium • Single layer of tall cells with oval nuclei toward the basal surface • Goblet cells are often found in this layer 16

Simple Columnar Epithelium 17

Simple Columnar Epithelium 18

Simple Columnar Epithelium • Functions 1. Secretion • Example: In the stomach, these cells secrete digestive enzymes 2. Absorption • Example: In the intestine, these cells absorb nutrients 19

Pseudostratified Columnar Epithelium • • • Single layer of cells with different heights; some do not reach the free surface Nuclei are seen at different levels May be ciliated (PCCE) or non-ciliated 20

Pseudostratified Columnar Epithelium 21

Pseudostratified Columnar Ciliated Epithelium (PCCE) 22

Pseudostratified Columnar Ciliated Epithelium (PCCE) • Functions 1. Protection • Example: Lines the upper respiratory tract. The cilia sweep debris toward the throat 2. Secretion • Example: May contain goblet cells (unicellular glands) that secrete mucus 23

Stratified Squamous Epithelium • Composed of several layers of cells • • • Top layer flat Bottom layers any shape Function in protection of underlying areas subjected to abrasion 24

Stratified Squamous Epithelium • Non-keratinized • Composed of several layers of cells • Top layer flat • Bottom layers any shape 25

Stratified Squamous Epithelium Non-Keratinized 26

Stratified Squamous Epithelium Non-Keratinized • Functions 1. Physical protection against abrasion and pathogens • Non-Keratinized is associated with “moist” areas • Mouth • Throat • Esophagus • Anus • Vagina 27

Stratified Squamous Epithelium Keratinized Looks “flakey” on the top 28

Stratified Squamous Epithelium Keratinized 29

Stratified Squamous Epithelium Keratinized • Functions 1. Physical Protection • Found only in the epidermis of the skin • Keratin is a protein that helps strengthen the cells against abrasion 30

Transitional Epithelium • • • Several cell layers, basal cells are cuboidal Apical cells are dome shaped when not stretched Apical cells are flat when stretched Only found in Urinary System Functions: 1. Allows expansion and recoil after stretching 31

Transitional Epithelium Distended bladder Empty bladder 32

Stratified Cuboidal and Columnar • Typically two cell layers thick Rare • Functions: • 1. Secretion • Found in some sweat and mammary glands 33

Stratified Cuboidal Epithelium 34

Stratified Cuboidal Epithelium 35

Stratified Columnar Epithelium • • • Limited distribution in the body To tell the difference between this and pseudostratified columnar, look at the nucleus. • The nuclei are lined up in a straight row Function 1. Protection • Found in the pharynx, male urethra, lining some glandular ducts, and anus 36

Stratified Columnar Epithelium 37

Stratified Columnar Epithelium 38

Connective Tissue • 4 Types 1. Connective Tissue Proper 2. Bone 3. Blood 4. Cartilage 39

Connective Tissue Features 1. 2. Specialized cells Matrix: Nonliving material between the cells that makes up most of the volume (ground substance + fibers) • Extracellular fibers • Ground substance: Composed chiefly of interstitial fluid, cell adhesion proteins, and proteoglycans • Specific composition varies between tissues (Blood=fluid, Cartilage=gel like, Bone=Solid) 40

Connective Tissue Fibers • Collagen Fibers: Fibrous protein molecules • • • Extremely tough High tensile strength Strongest type of fibers in connective tissue. 41

Connective Tissue Fibers • Elastic Fibers: Form branching networks • • Elastin: a rubber like protein that allow it to act like a rubber band snap back to its original shape after it is stretched Reticular Fibers: Forming delicate networks • Fine collagenous fibers (with a different chemical structure) branch extensively • Surround small blood vessels and support soft tissue organs 42

Cells of Connective Tissue Proper 1. Fibroblasts: Secrete the matrix 2. Macrophages: Scavenger cells that engulf pathogens or damaged cells 3. Adipocytes: Fat cells 4. Mesenchymal Cells: Stem cells 5. Mast cells: Stimulate local inflammation: contain histamine and heparin 6. Lymphocytes/microphages: WBC involved in immunity 43

Areolar Connective Tissue (Loose) • • • Gel like matrix Contains all 3 fiber types Functions: 1. 2. • Wraps and cushions organs Holds and conveys tissue fluid Locations: 1. 2. 3. Under epithelial tissues Packages organs Surrounds capillaries 44

Areolar Connective Tissue (Loose) Fibroblast Collagen fiber Macrophage Elastic fiber 45

Adipose Tissue (Loose) • Function: 1. 2. Storage of lipid molecules Insulation 46

Reticular Connective Tissue (Loose) • • Network of reticular fibers in a loose ground substance Functions 1. • Soft internal skeleton that supports other cell types Locations 1. 2. 3. Lymph nodes Bone marrow Spleen 47

Reticular Connective Tissue (Loose) 48

Dense Regular Connective Tissue • • • Primarily parallel collagen fibers Major cell type: fibroblast Functions: 1. • Withstands great tensile stress pulling in one direction Locations: 1. 2. 3. Tendons Ligaments Aponeuroses 49

Dense Regular Connective Tissue 50

Dense Irregular Connective Tissue • • Irregularly arranged collagen fibers Functions: 1. 2. • Withstands tension exerted in many directions Provides structural strength Locations: 1. 2. 3. Dermis of skin Submucosa of digestive tract Fibrous capsules of organs and joints 51

Dense Irregular Connective Tissue 52

Elastic Connective Tissue (Dense) • • • Dense regular CT dominated by elastic fibers Functions: 1. Stabilizes positions of vertebrae and penis 2. Cushions and permits expansion and contraction of organs Locations: 1. Between vertebrae 2. Ligaments supporting penis, transitional epithelia 3. Blood vessel walls 53

Elastic Connective Tissue (Dense) 54

Blood: Hematopoietic Tissue • Functions: 1. Transportation 2. Immunology 3. Hemostasis 55

Bone: Osseous Tissue • Functions: 1. Lever for muscles 2. Mineral storage 3. protection 56

Hyaline Cartilage • Functions: 1. Stiff but flexible support 2. Reduces friction between bony surfaces • Locations: 1. Articular surfaces 2. Larynx 3. Trachea 4. Nasal septum 57

Elastic Cartilage • Functions: 1. • Support, but flexible Locations: 1. 2. Ear Epiglottis 58

Fibrocartilage • Functions: 1. 2. • Resists compression Prevents bone-tobone contact Locations: 1. 2. 3. Meniscus of knee Pubic symphysis Intervertebral discs 59