Biology 351 Comparative Anatomy Dr. Tony Serino Tissues Biology 351 Comparative Anatomy Dr. Tony Serino

Tissues: Are a group of cells and their associated extracellular substances which perform a specific task Four basic types: Epithelium –cover a surface Muscular –able to contract Nervous –initiate and conduct electrical signals Connective –protect, support and bind all other tissues together

Epithelium Cover a surface –this allows them to control absorption, secretion, act as barrier to external environment, and control surface properties, such as friction. Named for surface cell shape: Squamous = flat cell (tile like) Cuboidal = cube (square in XS) Columnar = tall rectangular Named for cell thickness Simple = single cell thick Stratified = >1 cell thick

Epithelium anchored by Basement Membrane Made of collagen fibers

Simple Squamous Epithelium Flattened cells Found in lining of blood vessels, wall of lung alveoli

Found in epidermis, lining of mouth, esophagus, vagina

-found in kidney tubules, ducts, ovary surface

Stratified Cuboidal Epithelium -found in the lumen of large ducts of the salivary glands and some sweat glands

Simple Columnar Epithelium -found in lining of GI tract, oviducts and small glands

-secretes mucous

Stratified Columnar Epithelium -found in male urethra

Pseudostratified Columnar Epithelium -appears stratified -found in respiratory tract and male’s ducts

Pseudostratified Columnar Epithelium; Trachea

Transitional Epithelium Able to change its stratification look Thereby, thinning the organ’s wall Found in urinary tract

Class Quiz on Epithelium

Muscular Tissue Ability to contract Functions in body movements and movement of structures within the body Three types: Skeletal muscle Cardiac muscle Smooth muscle

Skeletal Muscle Voluntary –consciously controlled normally Long, cylindrical, multi-nucleated cells Has striations –due to arrangement of contractile proteins Each cell directly connected to nervous system

Cardiac Muscle Involuntary –not under conscious control Short, branched, single nucleated cells Striated, spontaneous contraction Cells act as syncytium –cells connected by gap junctions; therefore, one contracts, they all contract

Smooth Muscle -no striations -small spindle shape -single nucleus -spontaneous contractions

Nervous Tissue Initiates and conducts electrical signals (action potentials) Coordinates all bodily functions Forms mind, emotions: all higher functions Responds to stimuli quickly Consists of neurons and neuroglia cells

Neuron Structures (Cell Body) Initial Segment of Axon (Nerve Endings)

Connective Tissue Protects, supports and binds all other tissues Made of cells and extracellular matrix (which consists of ground substances (water, minerals, cell adhesion molecules, proteoglycans (with GAGs), etc.) and fibers (collagen and elastin)

Connective Tissues CT proper Loose Dense includes areolar, reticular, and adipose (considered specialized by some) Connects tissues but allows space for cells to reside or pass through Dense includes dense regular (fibrous or elastic) and dense irregular CT Matrix dominated by fibers (little empty space) Dense regular CT is avascular

Loose Areolar CT Most abundant CT in body Found in most tissues Fibroblast cells create and maintain the extracelluar matrix Allows for the passage of nerves, blood vessels, etc. Has mixture of collagen and elastin fibers

Reticular CT Contains reticular fibers which are a thin form of collagen Acts as the framework of organs Created and maintained by fibroblasts

Adipose Scattered throughout body but densely packed in certain regions such as subcutaneous layer of skin and on external surface of many organs Little extracellular matrix Functions as energy reserve and cushioning of internal components

Note how cytoplasm is moved to one side of large fat inclusion bodies.

Dense regular: Elastic CT of an Artery Elastin fibers dominate matrix and maintained by fibroblasts Allows for great flexibility and elasticity Spaces between fibers filled with other tissues Found in large arteries, dermis, lungs, bladder and elastic ligaments of spine

Dense Regular CT Fibroblasts secrete massive amount of collagen arranged in parallel bundles, little space in between Avascular Found in tendons, ligaments, organ capsules, sclera

Dense Irregular CT Collagen fibers arranged in random fashion, leaving spaces for BV, nerves, etc. Found in dermis of skin

Connective Tissue CT proper Cartilage Consists of Chondrocytes in lacunae Develop from Chondroblasts that are maintained at edge of tissue in a perichondrium layer Both appositional (edge) and interstitial growth possible Cartilage is dependent on surrounding tissue for nutrients through diffusion; it is avascular Three types: Hyaline Cartilage –more ground substance present Elastic Cartilage –more elastin fibers present Fibrocartilage –more collagen fibers present

Hyaline Cartilage Most abundant form of cartilage, found in articular cartilages, ribs, tip of nose, tracheal rings, etc. Ground substances dominate matrix with collagen outnumbering elastin fibers

Elastic Cartilage Seen where structure needs to snap back to original shape Located in pinna and epiglottis Matrix dominated by elastin fibers

Fibrocartilage Occurs where great strength is needed, collagen fibers dominate matrix Located in slightly moveable joints; such as, vertebral discs and pubic symphysis

Connective Tissue CT proper Cartilage Bone Consists of osteocytes in lacunae Develop from osteoblasts maintained in surrounding layer called periosteum Formed into osteons (Haversian systems) Highly vascular CT Only appositional growth allowed

Bone

Connective Tissue CT proper Cartilage Bone Blood Liquid CT (no fiber content, all proteins soluble in water) Consists of RBCs, WBCs, and platelets (thrombocytes) Developed from hematocytoblast

Blood RBC WBC Platelet

Connective Tissue CT proper: Loose and Dense Cartilage Bone Blood Embryonic CT –found mostly in embryonic stages Mesenchyme –archetype cell for all CT (some persist as stem cells in the adult Mucous CT –temporary CT found in umbilical cord

Identify this CT.

Identify this CT, it is the most abundant CT in the body.

Identify each type of muscle.

Identify the epithelium.

Identify the epithelium.

Identify the epithelium.

Identify the epithelium.