Animal Tissues and Organ Systems Chapter 33 AP Biology Spring 2011

Epithelial Tissue Chapter 33.1

General Characteristics Epithelium: sheet like tissue of cells that are close together with little extracellular material between them One free surface is exposed to outside environment or to some body fluid Opposite side form basement membrane, incorporate adhesion proteins (integrins, cadherins). Anchor epithelium to other tissues.

Types of Epithelium Simple Squamous: Description: Friction-reducing slick, single layer of flattened cells Common Locations: lining of blood and lymph vessels, heart; air sacs of lungs; peritoneum Function: diffusion, filtration, secretion of lubricants

Types of Epithelium Simple Cuboidal: Description: single layer of squarish cells Common Locations: ducts, secretory part of small glands; retina; kidney tubules; ovaries, testes; bronchioles Function: secretion, absorption

Types of Epithelium Simple Columnar: Description: single layer of tall cells; free surface may have cilia, mucous secreting glandular cells, microvilli Common Locations: glands, ducts, gut, part of uterus, small bronchi Function: secretion, absorption, ciliated types move substances

Types of Epithelium Simple Epithelium: cells form a layer that is only one cell thick Stratified Epithelium: cells form two or more layers Outer layer of skin: stratified squamous

Glandular Epithelium Gland cells occur only in epithelia Cells secrete products, that are used elsewhere Glands: saclike, secretory organs that open to the free epithelial surface

Glandular Epithelium Exocrine Glands: secrete oils, mucous, saliva, tears, milk, digestive enzymes, earwax Ducts or tubes that open into free epithelial surface

Glandular Epithelium Endocrine Glands: have no ducts, secrete their products, hormones, directly into interstitial fluid Hormone molecules diffuse into neighboring blood capillaries, circulatory system transports them to target cells in needed tissues

Cell Junctions Cell junctions connect adjoining cells 3 types

Cell Junctions Adhering Junctions: like spot welds, lock adjoining cells together Profuse in skin and tissues subject to abrasion

Cell Junctions Tight Junctions: stop most substances from leaking across a tissue Rows of proteins fuse cells Dissolved substances pass through cells to get to opposite surface Selective about what enters

Cell Junctions Gap Junctions: permit ions and small molecules to pass freely from cytoplasm of one cell to another Open communication channels abundant in heart muscles and tissues where actions of cells must be swiftly coordinate

Connective Tissues Chapter 33.2

Connective Tissue Connective Tissue: consist of cells scattered within an extracellular matrix of their own secretions Fibroblasts are main type of cell (except in blood) Make and secrete structural fibers of collagen and elastin into matrix

Soft Connective Tissue Loose Connective Tissue: fibroblasts and fibers dispersed widely through the matrix Most common type in vertebrate body, helps hold organs and epithelia in place

Soft Connective Tissue Fibrous, Irregular Connective Tissue: matrix is packed with many fibroblasts and collagen fibers that are positioned every which way Dense irregular tissue is component of skin Supports internal muscles, forms protective capsules around organs that do not stretch much

Soft Connective Tissue Fibrous, Regular Connective Tissue: orderly rows of fibroblasts between parallel, tightly packed bundles of fibers Organization prevents tares Tendons and ligaments Tendons connect skeletal muscles to bones Ligaments attach bone to bone Elastic fibers in tissue matrix facilitate movement in joints

Specialized Connective Tissue Cartilage: tissue of fine collagen fibers packed in a rubbery, compression-resistant matrix – Specialized cells secrete rubbery chondrin, which imprisons them Human skeleton started out as cartilage, bone tissue replaced most No blood vessels, substances move by diffusion Cells do not divide often in adults

Specialized Connective Tissue Cartilage: What parts of our bodies are still made up of cartilage? Outer ear, nose, throat, protects and cushions joints between limb bones and between vertebral column bones What organisms has a cartilage skeleton? Sharks

Specialized Connective Tissue Bone Tissue: hardened connective tissue with living cells imprisoned in their mineralized secretions Main tissue of bones (organs that interact with muscles to move body and protect organs)

Specialized Connective Tissue Adipose Tissue: energy reservoir Cells get so swollen with stored fat that their nucleus and a few fibroblast nuclei are flattened and pushed to one side Little extracellular matrix but many fine blood vessels that move fats to and from cells Fat deposits form insulating layer under skin and cushion body parts; accumulate around some organs (kidneys, heart)

Specialized Connective Tissue Blood: a connective tissue because its cellular components arise from stem cells in bone (connective tissue) Blood cells suspended in plasma Plasma: fluid extracellular matrix that functions in transport and heat transfer Made of: water, gases, proteins, ions, sugars

Specialized Connective Tissue Blood: Plasma holds red blood cells (RBC), white blood cells (WBC) and platelets RBC: get oxygen to metabolically active tissues and get rid of carbon dioxide and wastes WBC: defend and repair tissues Platelets: function in blood clotting

Muscle Tissues Chapter 33.3

Muscle Tissues In muscle tissues, cells contract Forcefully shorten in response to stimulation, then relax and passively lengthen Coordinated contractions of layers or rings of muscles move the whole body or its component parts

Skeletal Muscle Tissues Skeletal Muscle Tissues: functional partner of bone or cartilage Help move and maintain the positions of the body and its parts Parallel arrays of long, cylindrical muscle fibers

Skeletal Muscle Tissues Fibers are not single cells Groups of cells fuse together and form each fiber Ends up with multiple nuclei Inside fiber are myofibrils: long strands with row after row of contractile units Gives striated or striped appearance

Skeletal Muscle Tissues Sarcomere: each unit; is contractile It has parallel interacting arrays of contractile proteins: actin and myosin Reflexes activate it, also can contract by thinking about it Called “voluntary muscles”

Cardiac Muscle Tissue Cardiac Muscle tissue: occurs only in heart wall Contains sarcomeres and looks striated Consists of single, branching cells that have a nucleus “Involuntary muscle”: usually cannot make its cells contract by thinking about it

Cardiac Muscle Tissue Cells abut at ends, where adhering junctions help keep them from being ripped apart during forceful contractions All cells contract as a unit Tissue has more mitochondria…why? Needs continuous supply of ATP from aerobic respiration to keep heart beating nonstop

Cardiac Muscle Tissue Heart Attack: Cardiac muscle does not store as much glycogen Glycolysis cannot do much when oxygen is scarce If something ends the flow of oxygen, cardiac cells will falter or die

Smooth Muscle Tissue Smooth Muscle Tissue: in the wall of many soft internal organs, including the stomach, bladder and uterus Single, unbranching cells, tapered at both ends, with one centrally positioned nucleus Not striated Contains actin and myosin, which are anchored to plasma membrane by intermediate filaments

Smooth Muscle Tissue Contracts more slowly than skeletal Contractions can be sustained longer Contractions drive many internal events Propel material through gut Shrink diameter of arteries Close sphincters