Houston Community College Lab 8 Animal Tissues Dr. Wendy Sera Houston Community College Biology 1407

Levels of biological organization are evident in animals Body contains trillions of cells Approximately 100 different types Tissue – group of similar cells performing a specific function Organ – multiple tissues forming a structure that performs a specific function or task Organ system – a team of organs working together to perform necessary functions for an organism

Levels of biological organization in the body of a mammal 1 cell kidneys 2 tissue ureters bladder 3 organ urethra 5 organism 4 organ system

Animals have four main categories of tissue epithelial tissue, connective tissue, muscle tissue, and nervous tissue.

Epithelial tissue covers organs and lines body cavities Epithelial tissue (epithelium) Forms external and internal linings of many organs and covers surface of body In order for substance to enter or exit body at digestive tract, lungs, or urinary tract, it must cross epithelial tissue Epithelial cells are connected to one another by tight junctions, adhesion junctions, and gap junctions Basement membrane – thin layers of proteins that anchor epithelium to underlying connective tissue

Types of epithelial tissue in vertebrates 1 Simple squamous tissue • lines lungs and blood vessels • protects. basement membrane

Types of epithelial tissue in vertebrates 2 Simple cuboidal tissue • lines kidney tubules, various glands • absorbs molecules. basement membrane

Types of epithelial tissue in vertebrates 3 Simple columnar tissue • lines small intestine, oviducts. • absorbs nutrients. goblet cell secretes mucus basement membrane

Types of epithelial tissue in vertebrates 4 Pseudostratified ciliated columnar tissue • lines trachea • sweeps impurities toward throat. cilia goblet cell secretes mucus basement membrane

Connective tissue connects and supports other tissues Most abundant and widely distributed tissue in vertebrates Binds organs together and provides support and protection Cells are widely separated by matrix Non-cellular material that varies from solid to semifluid to fluid Usually has fibers, notably collagen fibers

Connective tissue connects and supports other tissues Loose fibrous connective tissue – occurs beneath epithelium and connects it to other tissues in organ Fibroblasts produce matrix that contains fibers Adipose tissue – loose connective tissue in which fibroblasts enlarge and store fat Limited matrix Dense fibrous connective tissue – contains more, closely-packed, collagen fibers Found in tendons, which connect muscles to bones, and ligaments, which connect bones to other bones

Types of connective tissue in vertebrates 1 Loose fibrous connective tissue • has space between components. • occurs beneath skin and most epithelial layers. • functions in support and binds organs. fibroblast elastic 240X collagen

Types of connective tissue in vertebrates 2 Adipose tissue • cells are filled with fat. • occurs beneath skin, around heart and other organs. • functions in insulation, stores fat. 200X nucleus

Types of connective tissue in vertebrates 3 Dense fibrous connective tissue • has collagen fibers closely packed. • occurs in dermis of skin, tendons, ligaments. • functions in support. 400× collagen nuclei of fibroblasts

Connective tissue connects and supports other tissues Cartilage – cells lie in small chambers called lacunae, separated by solid, yet flexible matrix Hyaline cartilage – most common type of cartilage, contains only very fine collagen fibers Bone – most rigid connective tissue consisting of extremely hard matrix of inorganic salts, notably calcium salts, deposited around collagen fibers Compact bone – composed of osteons

Types of connective tissue in vertebrates 4 Hyaline cartilage • has cells in lacunae. • occurs in nose and walls of respiratory passages; at ends of bones, including ribs. • functions in support and protection. 250X chondrocytes within lacunae matrix

Types of connective tissue in vertebrates 5 Compact bone • has cells in concentric rings. • occurs in bones of skeleton. • functions in support and protection. central canal osteon 320x osteocyte within a lacuna canaliculi

Connective tissue connects and supports other tissues Blood – composed of several types of cells suspended in liquid matrix called plasma Matrix (i.e., plasma) is not made by cells Transports nutrients and oxygen to cells and removes their wastes Helps distribute heat and plays role in fluid, ion, and pH balance

Connective tissue connects and supports other tissues Blood contains two types of cells: Red blood cells – small, biconcave, disk-shaped cells without nuclei Hemoglobin combines with oxygen to transport oxygen White blood cells – usually larger than red blood cells, have nucleus Fight infection by phagocytosis or through antibodies Platelets – cell fragments involved in clotting Lymph – liquid connective tissue located in lymphatic vessels Derived from tissue fluid

Composition of blood, a liquid connective tissue plasma white blood cells red blood cells white blood cell Test tube platelets red blood cell plasma Microscopic slide

Muscular tissue is contractile and moves body parts Contractile tissue that contains contractile protein filaments actin and myosin Types: Skeletal muscle – voluntary muscle, striated appearance, found in muscles attached to skeleton Cardiac muscle – involuntary, striated, found only in walls of heart Smooth muscle – involuntary, lacks striations, found in walls of viscera and blood vessels Also called visceral muscle

Types of muscular tissue 1 Skeletal muscle • has striated cells with multiple nuclei. • occurs in muscles attached to skeleton. • functions in voluntary movement of body. 250X striation nucleus

Types of muscular tissue 2 Cardiac muscle • has branching, striated cells, each with a single nucleus. • occurs in the wall of the heart. • functions in the pumping of blood. • is involuntary. 250× intercalated disk nucleus

Types of muscular tissue 3 Smooth muscle • has spindle-shaped cells, each with a single nucleus. • cells have no striations. • functions in movement of substances in lumens of body. • is involuntary. • occurs in blood vessel walls and walls of the digestive tract. 400× smooth muscle cell nucleus

Nervous tissue communicates with and regulates the functions of the body’s organs Nervous tissue coordinates body parts and allows animal to respond to environment Neuron has three parts: Dendrite – extension that conducts signals toward cell body Cell body – contains nucleus and major concentration of cytoplasm Axon – extension that conducts nerve impulses Nerves contain only axons

Nervous tissue communicates with and regulates the functions of the body’s organs Neuroglia outnumber neurons as much as 50 to 1 Support and nourish neurons May directly contribute to brain function Evidence of communication Form plasma-like solution called cerebrospinal fluid Supports and nourishes brain and spinal cord

Parts of a neuron and types of neuroglia dendrite Neuron nucleus cell body Astrocyte Microglia Oligodendrocyte myelin sheath axon

Parts of a neuron dendrite nucleus cell body axon Micrograph of neuron