Ch. 4 Tissues
Cells are the basic unit of life Organism Organ System Organs Tissues Cells
Living thing A group of organ systems working together
Group of organs working together Each system has a specific job Ex: Digestive system Break down food Depends on other systems too
Two or more tissues working together Ex: Heart Stomach Leaf Root
Similar cells that work together to perform a specific function Organized into groups and layers Four basic types: 1) Epithelial 2) Connective 3) Muscle 4) Nervous
Epi= upon Widespread Cover and line internal organs Cover body surfaces Compose glands
Protection Skin Lining of respiratory tract Absorption Lining of digestive tract Secretion Glands Excretion Sensory reception
Always one free surface = Apical Exposed to outside or to open internal space Other surface = Basal = Basement membrane Lower surface Anchored to connective tissue Nonliving layer Thin
Avascular No blood supply Nutrients diffuse from underlying connective tissue (vascular) Can regenerate Readily divide Heal rapidly Ex: skin, stomach, intestines
Tightly packed Little intercellular material Good protective barriers Ex: Outer layer of skin Lining of stomach Lining of mouth
9 Types Most have two names: First name Number of layers Simple Stratified Second name Shape of cells Squamous Cuboidal Columnar
Usually very thin Single layer of cells
A) Simple squamous epithelium Single layer Thin, flat cells Easily damaged Broad, thin nuclei Squamous =flat
Cells fit together tightly Like floor tiles Fried egg shape Usually form membranes Filtration Diffusion Ex: Capillaries Alveoli Body cavity linings
B) Simple cuboidal epithelium Single layer Cube shaped Central, spherical nucleus Covers ovaries Common in glands and ducts Salivary glands Pancreas Liver Thyroid Kidneys
C) Simple columnar epithelium Single layer Elongated like columns thick Nuclei located at about the same level near basement membrane May have cilia on free surface
Nonciliated Lines uterus and most digestive organs Ciliated Secretion and absorption microvilli tiny extentions that increase surface area Fallopian tubes Moves egg
Goblet cells Secrete mucus (protective fluid) onto free surface Mucous membranes Line body cavities that open to outside
D) Pseudostratified Columnar Epethelium Pseudo = false Appears layered, but is not Nuclei at different levels Many have cilia and goblet cells Mainly absorption and secretion Line respiratory tract
Stratified Two or more layers Thicker More durable Function in protection
E) Stratified squamous epithelium Several layers thick Cells divide in deeper layers New ones push old ones up
Cells at free edge are squamous Cuboidal at basement membrane Sometimes cells alive on free surface: Stays soft and moist Ex: Mouth Esophagus Vagina Anal canal
Forms Epidermis outer layer of skin Dead cells on free surface Keratin protein that forms in old cells Keratinization produces dry, tough, protective covering Effective barrier Good stuff in, bad stuff out
F) Stratified cuboidal epithelium Two or three layers Line lumen space within tubular structure Ducts of: Sweat glands Salivary glands Mammary glands Pancreas Parts of reproductive system
G) Stratified columnar epithelium Several layers Top cells = columnar (elongated) Bottom cells = cube shaped Rare Male urethra and vas deferens Pharynx
H) Transistional Epithelium Specialized Stretches as tension increases Forms linings Urinary system Cells change shape Cuboidal then flatten as stretched
I) Glandular Epithelium Consists of cells (glands) that make and secrete substances into ducts or body fluids Usually found within columnar or cuboidal epithelia
Two major types 1) Exocrine Secrete products into ducts that open onto internal or external surface Ex: Sweat glands Oil glands Liver Pancreas
A) Merocrine Most common release water, protein rich fluids by exocytosis Ex: Salivary glands Pancreatic glands Sweat glands
i) Serous cells watery secretion, many enzymes (serous fluid) Common in linings of body cavities ii) Mucous cells secretion is thicker (mucus) Rich in mucin (glycoprotein) Common in digestive and respiratory systems
Exocrine Glands B) Apocrine lose small portions of cell body during secretion Ex: mammary glands and external ear canal
C) Holocrine entire cell lyses during secretion Ex: Sebaceous glands of skin
Two major types: 2) Endocrine Ductless Products secreted into tissue fluid or blood Ex: Thyroid Adrenal Pituitary
Characteristics: Cells farther apart than epithelial Abundance of matrix Intercellular material Nonliving Cells can usually divide Most vascular Except tendons, ligaments, cartilage
Functions: Bind structures Support and protection Framework Fill spaces Store fat Produce RBCs Prevent infections Repair tissue damage
Cell types: A) Fixed cells stable # s i) Fibroblasts most common Large, star-shaped Produce fibers ii) Mast cells large Release heparin and histamine
Cell Types: B) Wandering cells temporary, usually in response to infection i) Macrophages (histocytes) Originate from WBCs Phagocytosis Scavengers Defenders
Macrophages and Fibroblasts
3 Types of fibers: All produced by fibroblasts 1) Collagenous ( white ) thick threads of protein collagen High tensile strength ability to resist pulling Flexible, but only slightly elastic Compose ligaments (connect bone to bone) and tendons (bone to muscle) Dense connective tissue
2) Elastic ( yellow ) made of protein elastin Complex, branching Weaker Stretchy Ex: vocal cords
3) Reticular Very thin Collagenous Highly branched Delicate support networks
Two categories: 1) Connective tissue proper A) loose B) adipose C) dense 2) Specialized Connective tissues A) cartilage B) bone C) blood
1) Loose connective tissue = Areolar tissue Most widely distributed Soft and pliable Spiderwebby appearance
Mainly fibroblasts Connective tissue glue Binds skin to organs Fills spaces b/w muscles Vascular Nourishes epithelial cells
Tissue soaks up excess water Inflammation Edema - An area swells and becomes puffy
2) Adipose tissue = fat Adipocytes Store fat in droplets in cytoplasm Nucleus near edge Signet ring cells
Locations: Beneath skin Behind eyeballs Around kidneys and certain joints Heart s surface Abdominal membranes Functions: Insulate, cushions, store energy
3) Dense connective tissue Closely packed collagen fibers and network of elastic fibers Short rows of fibroblasts separated by collagen fibers Very strong Tendons Ligaments Sclera of eye Poor blood supply Slow healing
1) Cartilage Rigid, but flexible Chondrocytes cartilage cells Infrequent division Occupy lacunae small chambers No direct blood supply Perichondrium encloses cartilaginous structure Provides blood supply
1) Hyaline cartilage Most abundant Fine collagen fibers Matrix with white, glassy appeance Found: Ends of bones Nose Rings in resp. system
2) Elastic Elastic fibers More flexible Found: External ears Larynx 3) Fibrocartilage Tough Many collagenous fibers Found: Intervertebral disks Knees Pelvic girdle
2) Bone Most rigid Layers of hard matrix Made of collagen fibers and calcium salts Protects and supports Active Heals well
Lamellae concentric layers of bone matrix that form around: Central canals (Haversian canals) longitudinal tubes Contain blood vessel Lacunae hollow cavity Contain osteocytes bone cells
Osteon cylindershaped unit of osteocytes and intercellular material
3) Blood Vascular Exchanges materials Helps maintain homeostasis Formed elements = RBCs,WBCs,platelets Plasma = fluid matrix
Specialized to contract Moves body parts Elongated cells are called muscle fibers
C) Cardiac A) Skeletal B) Smooth
Voluntary conscious control flesh Gross body motions Connected to bones or skin
Cells: Long Cylindrical Multinucleated Nuclei near edge Striated
Involuntary Visceral muscle Found in walls of hollow organs Stomach Blood vessels Uterus Cells: No striations Spindle-shaped One nucleus Central
C) Cardiac muscle Involuntary Found in heart only! Contracts Heart pumps Propels blood Cardiac muscle cells Striations Branching One nucleus Intercalated disks Where one cell touches another
4) In brain, spinal cord, and nerves Neurons = nerve cells Receive and conduct impulses Coordinate, regulate, and integrate many body functions Neuroglial Cells = supporting cells Support and bind Help supply nutrients Connect cells to blood vessels Carry out phagocytosis
Neuron Neuroglial cells
Zygote Fertilized egg Embryonic cells begin to specialize By birth organs are well developed and functioning Body continues to grow
Cell division Most cells undergo mitosis until end of puberty Adult body size reached Then only certain cells routinely divide Ex: Skin Intestinal cells
Cell division Liver cells stop dividing at adult size Still have ability if some cells need to be replaced Amitotic tissue Lose ability to divide Ex: Heart muscle Nerve tissue
Aging Begins once maturity is reached Debate over aging: Result of chemical insults? Alcohol Pollutions Shortages of key substances Cumulative effect