What are the four tissues of the body? Our body is made from these 4 tissues

Epithelial Tissue Covers exposed surfaces Lines internal passageways Forms glands

Connective Tissue Fills internal spaces Supports other tissues Transports material - cells Stores energy

Muscle Tissue Specialized for contraction Skeletal muscle, heart muscle, and walls of hollow organs

Neural Tissue Carries electrical signals from 1 part of the body to another

KEY CONCEPT Tissues are collections of cells and cell products that perform specific, limited functions 4 tissue types form all the structures of the human body: epithelial, connective, muscle, and neural

What are the special structures and functions of epithelial tissues?

Characteristics of Epithelia 1.Cellularity (cell junctions) 2.Polarity (apical and basal surfaces) 3.Attachment (basal lamina) 4.Avascularity 5.Regeneration

Functions of Epithelial Tissue 1.Provide physical protection 2.Control permeability 3.Provide sensation 4.Produce specialized secretions (glandular epithelium)

Specializations of Epithelial Cells 1.Move fluids over the epithelium (protection) 2.Move fluids through the epithelium (permeability) 3.Produce secretions (protection and messengers)

Figure 4–1 Free Surface and Attached Surface Polarity: apical and basolateral surfaces

Increasing Surface Area Microvilli increase absorption or secretion Cilia (ciliated epithelium) move fluids

Effective Barriers Physical integrity is maintained by: intercellular connections attachment to basal lamina maintenance and repair

Cell Junctions Form bonds with other cells or extracellular material: tight junctions gap junctions desmosomes

Tight Junctions Between 2 cell membranes Figure 4–2b

Tight Junctions Adhesion belt attaches to terminal web Prevents passage of water and solutes Isolates wastes in the lumen

Gap Junctions Allow rapid communications Figure 4–2c

Gap Junctions Held together by channel proteins (junctional proteins, connexons) Allow ions to pass Coordinated contractions in heart muscle

Desmosomes CAMs, dense areas, and intercellular cement Figure 4–2d

Desmososmes Button desmosomes Ties cells together Allow bending and twisting

Attachment to Basal Lamina Hemidesmosomes Figure 4–2e

Basal Lamina Lamina lucida: thin layer secreted by epithelia barrier to proteins Lamina densa: thick fibers produced by connective tissue strength and filtration

Repairing and Replacing Epithelia Epithelia are replaced by division of germinative cells (stem cells) Near basal lamina

Classes of Epithelia Based on shape and layers Table 4–1

Layers Simple epithelium: single layer of cells Stratified epithelium: several layers of cells

Cell Shape Squamous epithelia: flat shaped Cuboidal epithelia: square shaped Columnar epithelia: tall shaped

Squamous Epithelia Simple squamous epithelium: absorption and diffusion Mesothelium: lines body cavities Endothelium: lines heart and blood vessels

Figure 4–3a Simple Squamous Epithelium

Figure 4–3b Stratified Squamous Epithelium

Protects against attacks Keratin proteins add strength and water resistance

Cuboidal Epithelia Simple cuboidal epithelium: secretion and absorption Stratified cuboidal epithelia: sweat and mammary ducts

Simple Cuboidal Epithelium Kidney tubules Figure 4–4a

Stratified Cuboidal Epithelium Sweat gland ducts Figure 4–4b

Transitional Epithelium Urinary bladder Figure 4–4c

Columnar Epithelia Simple columnar epithelium: absorption and secretion Pseudostratified columnar epithelium: cilia movement Stratified columnar epithelium: protection

Simple Columnar Epithelium Intestinal lining Figure 4–5a

Pseudostratified Columnar Epithelium Trachea Figure 4–5b

Stratified Columnar Epithelium Salivary gland duct Figure 4–5c

Mechanisms of Glandular Secretion PLAY Glandular Epithelia Endocrine and exocrine glands Figure 4–6

Endocrine Glands Release hormones: into interstitial fluid no ducts

Exocrine Glands Produce secretions: onto epithelial surfaces through ducts

Modes of Secretion Merocrine secretion (GA produces and secreted by vesicles) Figure 4–6a

Modes of Secretion Apocrine secretion (GA produces and released by shedding cytoplasm) Figure 4–6b

Modes of Secretion Holocrine secretion (released by bursting and killing the cell) Figure 4–6c

Types of Secretions Serous glands: watery secretions Mucous glands: secrete mucins Mixed exocrine glands: both serous and mucous

Gland Structure Exocrine glands can be classified as: unicellular glands multicellular glands

Structure of Multicellular Exocrine Glands Structural classes of exocrine glands Figure 4–7 (1 of 2)

Structure of Multicellular Exocrine Glands Figure 4–7 (2 of 2)

What are the structures and functions of different types of connective tissues?

Connective Tissues Connect epithelium to the rest of the body (basal lamina) Provide structure (bone) Store energy (fat) Transport materials (blood) Have no contact with environment

The Matrix The extracellular components of connective tissues (fibers and ground substance): majority of cell volume determines specialized function

Classification of Connective Tissues Connective tissue proper: connect and protect Fluid connective tissues: transport Supportive connective tissues: structural strength

Connective Tissue Proper Figure 4–8

Categories of Connective Tissue Proper Loose connective tissue: more ground substance, less fibers e.g., fat (adipose tissue) Dense connective tissue: more fibers, less ground substance e.g., tendons

8 Cell Types of Connective Tissue Proper Fibroblasts Macrophages Adipocytes Mesenchymal cells Melanocytes Mast cells Lymphocytes Microphages

Fibroblasts The most abundant cell type: found in all connective tissue proper secrete proteins and hyaluronan (cellular cement) Makes ground substance and structural fibers

Macrophages Large, amoeba-like cells of the immune system: eat pathogens and damaged cells fixed macrophages stay in tissue free macrophages migrate

Adipocytes Fat cells: each cell stores a single, large fat droplet

Mesenchymal Cells Stem cells that respond to injury or infection: differentiate into fibroblasts, macrophages, etc.

Melanocytes Synthesize and store the brown pigment melanin

Mast Cells Stimulate inflammation after injury or infection: release histamine and heparin Basophils are mast cells carried by blood

Lymphocytes Specialized immune cells in lymphatic system: e.g., plasma cells which produce antibodies

Microphages Phagocytic blood cells: respond to signals from macrophages and mast cells e.g., neutrophils and eosinophils

Fibers in Connective Tissue Proper Collagen fibers: most common fibers in CTP long, straight, and unbranched strong and flexible resists force in 1 direction e.g., tendons and ligaments

Fibers in Connective Tissue Proper Reticular fibers: network of interwoven fibers (stroma) strong and flexible resists force in many directions stabilizes functional cells (parenchyma) and structures e.g., sheaths around organs

Fibers in Connective Tissue Proper Elastic fibers: contain elastin branched and wavy return to original length after stretching e.g., elastic ligaments of vertebrae

Loose Connective Tissues The packing materials of the body 3 types in adults: areolar adipose reticular

Areolar Tissue Least specialized Open framework Viscous ground substance Elastic fibers Holds blood vessels and capillary beds: e.g., under skin (subcutaneous layer)

Adipose Tissue Contains many adipocytes (fat cells) Figure 4–10a

Adipose Cells Adipocytes in adults do not divide: expand to store fat shrink as fats are released Mesenchymal cells divide and differentiate: to produce more fat cells when more storage is needed