Chapter 5 Tissues

Introduction Cells are arranged in tissues that provide specific functions for the body. Cells of different tissues are structured differently, which leads to their differences in function. The tissues of the human body include four major types. Epithelial Connective Muscle Nervous

Epithelial Function Location Characteristics Protection, secretion, absorption, excretion Sensory reception Location Covers your body surfaces, covers and lines internal organs, compose glands Characteristics Lack blood vessels, readily divide, cells are tightly packed Anchored to a basement membrane Replaced frequently

Epithelial Epithelium- tissue that constitutes the outermost layer of the skin. Carcinoma is a cancer originating from epithelium tissue. About 90% of all cancers originate from epithelium tissue.

Types of Epithelium 1) Simple Squamous 2) Simple Cuboidal 3) Simple Columnar 4) Pseudostratified Columnar 5) Stratified Squamous 6) Stratified Cuboidal 7) Stratified Columnar 8) Transitional 9) Glandular

Simple Squamous Epithelium Made up of a single layer of thin, flattened cells. Suited for diffusion Exchanges gases in the lungs Lines: Blood and lymph vessels Body cavities A basement membrane forms between epithelial and connective tissues

Simple Squamous Epithelium

Simple Cuboidal Epithelium Consists of a single layer of cube-shaped cells with a centrally located nuclei. It functions in secretion and absorption in the kidneys, and in secretion in glands.

Simple Columnar Epithelium Cells are longer than they are wide Single layer of cells nuclei are located near the basement membrane May be ciliated It lines: The uterus, stomach, and intestines It also protects underlying tissues, secretes digestive fluids, absorbs nutrients

Simple Columnar Epithelium Inner lining organs of the digestive system contain this type. Goblet Cells: Secrete Mucus Embedded within the tissues Unicellular gland. Have microvilli Increases the surface area for available for absorption.

Pseudostratified Columnar Epithelium Appear Layered (but are not truly layered) Varying positions of the nuclei Cilia may be present Also, Goblet Cells Function to line and sweep debris from respiratory tubes. Commonly found forming the inner lining of the respiratory passages.

Stratified Squamous Epithelium Made up of layers of flattened cells Designed to protect underlying layers. Where is it found? It makes up the outer layer of skin. It lines the mouth, throat Outer layers of cells undergo keratinization Does not occur where tissues remain moist throat

Stratified Cuboidal Epithelium 2-3 layers of Cuboidal Cells Several layers of cells provides more protection than one single layer. Lines: Sweat glands Salivary glands Pancreas Mammary glands

Stratified Columnar Epithelium Several layers of cells- stratified Where is it found? Vas deferens Parts of the male urethra Parts of the pharynx

Transitional Epithelium Designed to distend and return to its normal size Lining of the urinary bladder Provides distensibility Keeps urine from diffusing back into the internal cavity

Glandular Epithelium Produces and secretes substances into ducts or into body fluids Exocrine- glands that secret products into ducts Endocrine (ductless) - glands that secret products into body fluids and blood

Glandular Epithelium Gland classification = way product is secreted Merocrine Glands Release fluid products – exocytosis Apocrine Glands Lose portions of their cell bodies during secretion Ex. Mammary glands Holocrine Glands Release entire cells Ex. Sebaceous glands

Connective Function Location Characteristics Bind, support, protect, fill spaces, store fat, produce blood cells, serves as framework, protect against infection, repairs tissue damage. Has an abundant matrix (unlike epithelial) Intercellular material Has good blood supply (except cartilage) Location Widely distributed throughout the body Characteristics Mostly have good blood supply; cells are farther apart then epithelial cells with extracellular matrix between

2 Major Types 1. Liquid or Vascular Connective Tissue 2. Solid Connective Tissue

Vascular Tissue Blood: Red blood cells (carry oxygen) White blood cells (fight infection) Platelets (cell fragments used for agglutination) Plasma (fluid intracellular matrix)

Major Cell Types Fibroblast Cell Macrophages (wandering) Most common Fixed, star-shaped cell Large Secretes Fibers Macrophages (wandering) Function Scavenger cells Defend against infection

Major Cell Types Mast Cells Large Located near blood vessels Release Heparin (anticoagulant) Histamine (promotes inflammation)

Connective Tissue Fibers Collagenous Fibers (white fibers) Made of: Collagen Add Strength (for holding body parts together) Elastic Fibers (yellow fibers) Elastin Stretchy Add Flexibility to certain types of connective tissues

Connective Tissue Fibers Reticular Thin collagenous Form supportive networks Osteocytes (bone cells) Arranged in concentric circles around the osteonic or Haversian Canals

Loose Connective (areolar) Tissue Forms: Delicate, thin membranes Binds body parts together Skin and underlying organs The majority of the cells are fibroblasts that are separated by a gel-like intracellular material that contains collagenous and elastic fibers.

Adipose Tissue Loose connective tissue Where is it found? Stores fat Beneath the skin Around joints Padding the kidneys, and internal organs Abdominal membranes

Adipose Tissue

Dense Connective Tissue (Fibrous Connective Tissue) Densly packed collagenous fibers Very Strong! Lacks a good blood supply Where is it found? Tendons and Ligaments

Cartilage Rigid connective tissue Enclosed within Perichondrium Provides a supportive framework Enclosed within Perichondrium Lacks a vascular system Healing takes longer Chondrocytes- cartilage cells Lie within the lacunae Small chamber within a gel-like fluid matrix

Cartilage Hyaline Cartilage Where is it found? Function? Most common White Abundant fine collagen fibers Where is it found? Ends of bones Function? Supports respiratory passages Trachea is composed of Hyaline Cartilage

Cartilage Elastic Cartilage Fibrocartilage Elastic Fibers Forms Framework Ex. External Ears & Parts of Larynx Fibrocartilage Collagenous Fibers Tough- Tissue Shock- absorbing Ex. Intervertebral Disks of Backbone Disks separate individual parts of backbone Ex. Knees, Pelvic Girdle

Bone Most Rigid Connective Tissue Matrix Contains: Functions: Deposits of Mineral Salts Collagen Functions: Internally Supports the Body Forms Muscle Attachments Site for Blood Cell Formation Osteocytes- Bone Cells Found in Lacunae Arranged in Osteons (concentric circles) Around osteonic canals interconnected by canaliculi

Bone Bone has a good blood supply, enabling rapid recovery after an injury.

Bone

Blood Composed of red and white cells Function: Suspended in plasma Liquid matrix Function: Transport substances throughout body

Muscle Function Location Characteristics Movement Attached to bones, in the walls of hollow internal organs, heart Characteristics Able to contract in response to specific stimuli

3 Major Types of Muscle Tissue 1) Skeletal 2) Smooth 3) Cardiac

Skeletal Muscle Tissue Attached to bone Controlled voluntarily Muscle Fibers Long, striated, cylindrical, many nuclei Major Characteristic Ability to contract from nervous impulse Least likely cell type to reprodue

Smooth Muscle Tissue Lacks Striations Uninucleate Spindle-shaped cells Involuntary Muscle Found in the walls of internal organs Ex. Stomach, Digestive Tract, blood vessels, urinary bladder

Cardiac Muscle Tissue 1. Cardiac muscle tissue is found only in the heart and consists of branching fibers that are connected to each other with intercalated disks. This is the band that occurs where two cardiac muscle cells join. 2. This involuntary muscle has a single nucleus in each cell but appears striated. 3. When cardiac muscle cells are damaged by a heart attack, they are usually replaced by “connective tissue cells”

Nervous Tissues: A. Nervous tissues are found in the brain, spinal cord, and nerves. B. Neurons, or nerve cells, conduct nervous impulses while helper cells, or neuroglia, support and nourish the neurons. C. Generally nervous tissue conducts nerve impulses from one neuron to another and it coordinates body activities.

Nervous Function Location Characteristics Transmit impulses for coordination, regulation, integration, and sensory reception Location Brain, spinal cord, nerves Characteristics Cells connect to each other and to other body parts