Ch. 3b tissues

There are four tissue types in the body Tissues There are four tissue types in the body Epithelial tissue Connective tissue Muscle tissue Nerve tissue

Characteristics of Epithelial Tissue Cells have: Polarity— apical (unattached/ free) and basal (attached) surfaces Apical surfaces: May bear microvilli /cilia Basal surface: Supported by a basement membrane

Characteristics of Epithelial Tissue Composed of closely packed cells Cells held together by tight junctions and desmosomes Avascular High rate of regeneration

Apical surface Basal surface Simple Apical surface Basal surface Stratified Figure 4.2a

Classification of Epithelia Ask two questions: How many layers? 1 = simple epithelium >1 = stratified epithelium

Classification of Epithelia What type of cell? Squamous Cuboidal Columnar (If stratified, name according to top layer of cells)

Disc- like nucleus Round, central nucleus Round to oval nucleus Squamous Round, central nucleus Cuboidal Round to oval nucleus Columnar (b) Classification based on cell shape.

Single layer of flat cells (a) Simple squamous epithelium Description: Single layer of flat cells Function: Diffusion/Filtration Location: Air sacs of lungs Lining of ventral body cavity Figure 4.3a

(b) Simple Cuboidal epithelium Description: Single layer of cubelike cells Function: Secretion/ absorption. Location: Glands and ducts

Description: Single layer of tall cells May have goblet cells (c) Simple Columnar epithelium Description: Single layer of tall cells May have goblet cells Function: Absorption and secretion Location: Lines most of digestive tract

(d) Pseudostratified Ciliated Columnar epithelium Description: Single layer of cells of differing heights on same basement membrane; May have goblet cells Function: Secretion, propulsion of mucus by ciliary action. Location: upper respiratory tract. Trachea

(e) Stratified squamous epithelium Description: Thick, surface cells squamous Two types: Non-Keratinized: alive Keratinized: surface cells dead & full of keratin Function: Protection in areas subjected to abrasion. Location: Non-keratinized: Lines cavities which open to exterior Keratinized: forms epidermis

(f) Transitional epithelium Description: Basal cells cuboidal/columnar Surface cells dome shaped or squamous (depends on degree of stretch) Function: Stretches readily Location: Lines hollow urinary organs Figure 4.3f

Glandular Epithelia Gland: consists of one/more cells that make and secrete a product (secretion) Two major types: Endocrine glands- ductless glands that secrete hormones into the blood stream Exocrine glands-have ducts that lead to a surface and secrete product onto surface/lumen leading to surface

Connective Tissue Most abundant and widely distributed tissue type Flow Chart:

Characteristics of Connective Tissue Connective tissues have: Varying degrees of vascularity Cells separated by nonliving extracellular matrix (ground substance and fibers)

Extracellular Matrix Ground substance Fibers Components: Interstitial fluid, Adhesion proteins (“glue”), Large polysaccharides Fibers Collagen Strongest, most abundant type; Provides tensile strength; form thick cables Elastic Long, thin, fibers; allow for stretch Reticular Short, fine, branched fibers that form an internal network (mesh) that is supportive to other cells

Cells of Connective Tissue “blasts” = Mitotically active and secretory cells “cytes” = Mature cells Fibroblasts in connective tissue proper Chondroblasts and chondrocytes in cartilage Osteoblasts and osteocytes in bone Hematopoietic stem cells in bone marrow

(j) Others: Osseous tissue Description: Hard, calcified matrix; osteocytes in lacunae; Central canal Function: Support, protection, attachment site for muscles. Lacunae Location: Bones Lamella Figure 4.8j

Connective Tissue: Cartilage Three types of cartilage: Hyaline cartilage Elastic cartilage Fibrocartilage

(g) Cartilage: Hyaline Description: most abundant of cartilage types;less hard and more flexible than bone; Chondrocytes in lacunae. Function: Supports,cushions, resists compressive stress. Location: Forms most of embryonic skeleton; articular cartilage; cartilages of nose, trachea, larynx. Chondrocyte in lacuna Matrix Costal cartilages

(h) Cartilage: Elastic Function: Also allows great flexibility. Chondrocyte in lacuna Location: Ear, epiglottis. Matrix

(i) Cartilage: Fibrocartilage Location: Intervertebral discs Chondrocytes in lacunae Intervertebral discs Collagen fiber

(d) Connective tissue proper: Dense regular connective tissue Description: Parallel collagen fibers Collagen fibers Function: Withstands tensile stress when pulling force is applied in one direction. Location: Tendons, most ligaments Nuclei of fibroblasts Shoulder joint Ligament Tendon

(e) Connective tissue proper: Dense irregular connective tissue Description: Irregularly arranged collagen fibers Nuclei of fibroblasts Function: Withstands tension exerted in many directions Location: Fibrous capsules of organs ,joints; dermis of skin Collagen fibers Fibrous joint capsule

(a) Connective tissue proper: Areolar connective tissue Description: Most widely distributed variety of CT Soft, pliable, like cobwebs Elastic fibers Function: Wraps and cushions organs Collagen fibers Location: Under epithelia of body, universal packaging material Fibroblast nuclei Epithelium Lamina propria

(b) Connective tissue proper: Adipose connective tissue Description: Closely packed adipocytes Function: Reserve fuel insulation; supports & protects organs. Nucleus of fat cell Location: Hypodermis; around kidneys and eyeballs; in abdomen; breasts. Adipose tissue Vacuole containing fat droplet Mammary glands

(c) Connective tissue proper: Reticular connective tissue Description: Network of reticular fibers Function: Fibers form a soft internal skeleton that supports other cells Location: Lymphoid organs (lymph nodes, bone marrow, and spleen). White blood cell (lymphocyte) Reticular fibers Spleen

(k) Others: blood Description: Red and white blood cells in a fluid matrix (plasma). Plasma Function: Transport of respiratory gases, nutrients, wastes, and other substances. Neutrophil Location: Contained within blood vessels. Red blood cells Lymphocyte

Muscle Tissue

(a) Skeletal muscle Description: Long, cylindrical, multinucleate cells; obvious striations. Striations Function: Voluntary movement Nuclei Location: Skeletal muscles attached to bones or occasionally to skin. Part of muscle fiber (cell) Photomicrograph: (approx. 460x).

(b) Cardiac muscle Description: Branching, striated, Have intercalated discs. Striations Intercalated discs Function: Propel blood into circulation; involuntary control. Location: Walls of the heart. Nucleus Photomicrograph: (500X);

(c) Smooth muscle Description: Spindle-shaped Cells; no striations; cells form sheets. Smooth muscle cell Function: Propels substances or objects; involuntary control. Location: Mostly in walls of hollow organs. Nuclei Photomicrograph: Sheet of smooth muscle (200x).

Nervous Tissue

Nervous tissue Description: Neurons w/ cell processes that extend from the cell body; Contains supporting cells Nuclei of supporting cells Neuron processes Cell body Axon Dendrites Cell body of a neuron Function: Transmit electrical signals from sensory receptors to effectors. Neuron processes Location: Brain, spinal cord, and nerves.

Steps in Wound Repair Inflammation Increased blood flow with healing components & clotting factors to damaged area (redness, swelling, pain, heat) due to the release of inflammatory chemicals Clot forms and exposed portion forms scab Organization and restored blood supply Granulation tissue forms=new capillaries and phagocytes and fibroblasts Regeneration and fibrosis Surface ET regenerates, scab detaches, underlying scar tissue

Scab Epidermis Blood clot in incised wound Migrating white blood cell Inflammatory chemicals Artery

Regenerating epithelium Area of granulation tissue ingrowth Fibroblast Macrophage

Regenerated epithelium Fibrosed area