HumanA&P 5: Tissues

5 Types of Tissues

1. Epithelial

2. Connective

3. Membranes

4. Muscular

5. Nervous

Tissue Preparation

• Fixed: preserved with solvent

• Sectioned: cut into slices thin enough to transmit light or electrons

• Stained: to enhance contrast, artifacts can interfere with image

Epithelial Tissue

• Covers inside/outside body surfaces

  • Surface epithelium

  • Glandular epithelium

• Roles around body:

  • Protection: barrier

  • Immune defence:

  • Secretion: glands

  • Transport: substance between tissues

  • Sensation: nerves within tissue

Connective Tissue

• Protects & supports body & organs

• Binds organs

• Stores energy reserves

• Provides immunity

Muscular Tissue

• Generates physical force needed to make body structures move

Nervous Tissue

• Detects changes in/out of body

• Transmits nerve impulses

• Coordinate body activities to maintain homeostasis

Surface Epithelium

• Outer covering of skin, some internal organs

• Lines body cavities

• Interiors of respiratory, digestive, urinary, reproductive systems

Glandular Epithelium

• Produce, store, secrete substances

  • Hormones

  • Proteins

  • Water

6 Locations of Epithelial Tissue

1. Esophagus

2. Trachea

3. Stomach

4. Small Intestines

5. Urinary Bladder

6. Palm

5 Epithelial Tissue Characteristics

1. Polarity

2. Specialized Contacts

3. Supported by Connective Tissues

4. Avascular, but Innervated

5. Regeneration

Epithelial Tissue: Polarity

• Apical surface: exposed to surface

• Basal surfaces: faces inward

  • Basal lamina

• Differences in structure & function

Epithelial Tissue: Specialized Contacts

• Tissues need to closely fit together

• Tight junctions: prevent molecules from passing through intercellular space

• Desmosomes: anchoring junctions, internal tension-reducing fibers

• Gap Junctions: intercellular communication, protein channels

Epithelial Tissue: Supported by Connective Tissues

• Basement membrane: resists stretching & tearing, reinforces sheet

• Basal lamina: specialized ECM secreted by epithelium, collagen fibers

• Reticular lamina: deep to basal lamina, thicker fibers

Epithelial Tissue: Avascular, Innervated

• No blood vessels

• Supplied by nerve fibers

Epithelial Tissues: Regeneration

• High regenerative capacities

• Stimulated by loss of apical-basal polarity and broken lateral contacts

Simple Epithelia

• Single layer of cells

• Absorption, secretion, filtration

Stratified Epithelia

• 2 or more layers thick

• Protection

• Named based on apical layer

3 Shapes of Epithelial Cells

• Squamous

• Cuboidal

• Columnar

Exocrine Gland

• Gland that secretes substances into a duct that is lined with epithelial cells

• Local effects

Endocrine Gland

• Secrete substances into bloodstream without use of ducts

• Distant effects

Simple Squamous Epithelium

• Cells flattened laterally

• Rapid diffusion

• 2 special cells based on locations:

  • Endothelium

  • Mesothelium

Simple Cuboidal Epithelium

• Single layer of cells, large nucleus

• Secretion & absorption

• Located:

  • Walls of smallest ducts of glands & kidney tubules

Simple Columnar Epithelium

• Single layer, tall cells

• Absorption & secretion of mucus, enzymes

• Located:

  • Digestive tract, gallbladder, ducts of some glands, bronchi, uterine tubes

Pseudostratified Columnar Epithelium

• Cells vary in height, single layered

• Secretion & movement of mucus

• Located:

  • upper respiratory tract

  • ducts of large glands

  • tubules in testes

Endothelium

• Special simple squamous epithelia

• Located:

  • Lining of lymphatic vessels

  • Blood vessels

  • Heart

Mesothelium

• Inner lining simple squamous cells produce & secrete serous fluid

• protective membrane that covers the lungs, abdomen, heart and testes

Stratified Squamous Epithelium

• Common stratified epithelia

• Surface is squamous, layers of cuboidal & columnar cells

• Located:

  • Keratinized: skin

  • Nonkeratinized: mouth, throat, esophagus, vagina, anus

Stratified Cuboidal Epithelium

• Rare

• 2 layers thick

• Located:

  • Sweat

  • Mammary glands

Stratified Columnar Epithelium

• Limited

• Transitional

• Located:

  • Male urethra

  • Glandular ducts

  • Transition areas

  • Apical columnar, basal cuboidal

Transitional Epithelium

• Basal cuboidal/columnar

• Cells can stretch to allow increase in urine

• Located:

  • Hollow urinary organs

  • Bladder, ureters, urethra

Endocrine Glands

• Secretions called hormones

• Enter interstitial fluid, diffuse into bloodstream without duct

Exocrine Glands

• Products enter ducts that empty from surface epithelium

• Secretions:

  • mucus

  • perspiration

  • oil

  • earwax

  • milk

  • saliva

  • digestive enzymes

Endocrine vs Exocrine Glands

3 Common Features of Connective Tissue

1. Specialized Cells

2. Extracellular Protein Fibers

3. Ground Substance Fluid

6 Connective Tissue Functions

1. Establishing framework for body

2. Transporting fluids & dissolved materials

3. Protecting delicate organs

4. Supporting, surrounding & interconnecting other types of tissues

5. Storing energy reserves

6. Defending the body from microorganisms

Connective Tissue: Structural Elements

• Arose from mesenchyme tissue

Composed of:

• Fibers

• Ground Substance

• Cells

Connective Tissue: Ground Substance

• Unstructured gel-like material; fills space between cells

• Components:

  • interstitial fluid

  • cell adhesion molecules

  • Proteoglycans

  • Water

Connective Tissue: Fibers

• Collagen

  • Strongest, abundant

• Elastic Fibers

  • elastin fibers allow for stretch

• Reticular Fibers

  • Short, fine, branched

Connective Tissue: Cells

• Blast cells

  • Fibroblasts: tissue proper, flat cells

  • Chondroblasts: cartilage

  • Osteoblasts: bone

• Cyte cells: maintain matrix

  • Less active form of blast cell

• Fat cells: adipocytes

• Leukocytes

  • Neutrophils

  • eosinophils

  • lymphocytes

• Mast Cells

  • initiate local inflammatory response

• Macrophages

Connective Tissue Proper

• Widely distributed in body

• Components of internal architecture of some organs

4 Basic Types:

1. Loose Connective Tissue (Areolar)

2. Dense Tissue

   • Dense Irregular Tissue

   • Dense Regular Tissue

3. Reticular Tissue

4. Adipose Tissue

3 Types of Dense Connective Tissues

• Dense Irregular

  • Collagen bundles

  • Resists tension

• Dense Regular (fibrous)

  • Organized collagen bundles

  • Tendons, ligaments

• Dense Regular (elastic)

  • Parallel elastic fibers

  • Large blood vessels & ligaments

Reticular Connective Tissue

• Type of connective tissue

• Forms fine networks of tissue that support small structures

Adipose Connective Tissue

• Fat cells

• Fat storage, insulation, shock absorption

Cartilage

• Matrix secreted from chondroblasts & chondrocytes

• Avascular, receives nutrients from perichondrium

• 80% water

• Lacks nerves

• 3 Types

3 Types of Cartilage

1. Hyaline Cartilage

2. Elastic Cartilage

3. Fibrocartilage

Hyaline Cartilage

• Most abundant

• Bluish glass

• long bones, nose, trachea, larynx, ribs

Elastic Cartilage

• More elastic

• Ears & epiglottis

Fibrocartilage

• Properties in between other cartilage

• Strong

• Knees, intervertebral discs & knee

Bone Cells

• Osteoblasts: build/break down bone

• Osteocytes: mature cells surrounded in ECM, maintenance

• Red Marrow: produces blood cells

• Yellow Marrow: triglyceride storage

• Functions:

  • Supports soft tissue

  • protects delicate structures

  • generates movement

Blood Composition

• Composition

  • Plasma

  • Plasma Proteins

  • Erythrocytes

  • Leukocytes

  • Platelets

4 General Membrane Types

1. Serous Membranes

2. Synovial Membranes

3. Mucous Membranes

4. Cutaneous Membranes

Serous Membranes

• Line pleural, pericardial, peritoneal cavities

• Mesothelium

• Outer lining is areolar tissue

• Continuous sheet

  • Visceral & parietal layers

Synovial Membranes

• Line cavities of freely moveable joints

  • hip, knee, elbow, shoulder

• Composed of connective tissue layers

  • Inner: synoviocytes secretes fluid

  • Outer: loose + dense irregular connective tissue

Mucous Membranes

• Line walls of hollow organs

• Inner epithelial layer faces organ lumen

  • Contains goblet cells

• Outer layer of areolar tissue

• Sometimes contains 3rd layer of smooth muscle tissue

Cutaneous Membranes

• Outer layer of keratinized stratified squamous epithelium

• Dermis: layer of loose connective tissue beneath epidermis + deeper layer of dense irregular tissue

3 Types of Muscular Tissue

1. Skeletal Muscle Tissue

2. Cardiac Muscle Tissue

3. Smooth Muscle Tissue

Skeletal Muscle Tissue

• Made of myofibril cells

  • Striated & multinucleated

• Contraction produces body movement

• Voluntary contractions

Cardiac Muscle Tissue

• Contraction pumps heart

• Involuntary contractions

• Cardiac myocytes striated, 1 nucleus

Smooth Muscle Tissue

• Slow wave contractions found in walls of many organs

• Involuntary contractions

• Flattened cells with 1 nucleus

Nervous Cells

• Makes up majority of brain, spinal cord, and nerves

1. Neurons

   • Capable of sending & receiving messages

   • Convert stimuli into nerve impulses

2. Glial Cells

   • Various functions

   • Do not generate nerve impulses