Chapter 4

Cells- form tissues that have specialized structure and function. vary in size, shape, & arrangement between tissues very similar with in tissues divide to replace or repair dead cells

Stem cells Divide and specialize into needed cell type Can travel to areas of the body needing repair or replacement. Pluripotent- give rise to many types of cells Multipotent/progenerator- restricted potential Bone marrow & brain marrow

Tissues Made of cells associate and organize to form organs with specialized functions 4 types-  Epithelial  Connective  Muscle  Nervous Tissues

Epithelial Tissue- 1 side always exposed to outside or internal open space Classified by shape and number of layers of cells Function-  Protection, secretion, absorption, excretion Characteristics-  lack blood vessels  Tightly packed with little intercellular material  Readily divide- healing quickly  Connected to tissue via thin non-living basement membrane  Gains nutrients from underlying connective tissues

Types of epithelium- Simple= single layer Simple Squamous  Site of diffusion and filtration  Lines vessels/air sacs Simple Cuboidal  Glands- secretion  Kidneys- secretion & absorption Simple Columnar-  tissue is thick for protection  Secretes digestive fluids & absorbs nutrients from digested food

Types of epithelium- Stratified= many layers Stratified Squamous  protection from organism entering or substances leaving Stratified Cuboidal  lining of glandular ducts  Mammary, sweat, salivary, pancreatic and reproductive glands Psuedostratified columnar  cilia move mucous secreted by goblet cells  Protection, secretion

Types of epithelium- Transitional  changes shape of cells in response to tension- cube shaped to elongated  provided protection from contents of urinary bladder from reentering body  Provides an expandable lining

Summary

Connective tissue Most abundant tissue in the body Characteristics  intercellular matrix of fibers and ground substance  Fluid, semisolid, solid, flexible to rigid  Generally have good blood supplies Function  Bind structures  Provide support & protection  Frameworks, fill spaces, store fat  Produce blood cells  Protect against infections  Help repair tissue damage

Connective tissue composition Fixed cells  Fibroblasts- most common Large star shaped cell Secrete protein into matrix  Mast cells- located near blood vessels Release heparin( prevent blood clotting Release histamine (reaction to allergies) Wandering cells  Macrophages-white blood cells Defense against infection Connective tissue fibers Collagenous fibers  thick threads of protein collagen  Arranged in long parallel flexible bundles  Holds structures together ( ligaments & tendons) Elastin fibers  bundles of protein elastin  Weaker than collagen fibers but more elastic  Yellow color- yellow fibers Reticular fibers  thin delicate collagen fibers for support

Types of Connective tissues- Dense connective 1. Tissue abundant collagen fibers 2. Appears white – white fibers  Regular: Tendons & ligaments Poor blood supply= slow healing  Irregular: found in dermis of skin

Types of Connective tissues- Loose connective tissue (areolar)  sparse collagen fibers  binds skin to underlying organs  fills spaces between muscles  underneath most types of epithelium

Types of Connective tissues- Adipose tissue  Adipocytes store fat droplets that form adipose tissue  Beneath the skin, spaces between organs and joints  Cushions, insulates, stores energy

Cartilage rigid connective tissue Function  Provides support, framework, attachments, protection and structure  for forming bones Structure  collagenous fibers in gel like ground substance  Chondrocytes located in small chambers (lacunae)  Cartilage lacks direct blood supply but gets nourishment from perichondrium by diffusion  Heals slowly, slow cell division

Types of cartilage tissues- Hyaline  most common type  Ends of bones, soft parts of nose, support rings of respiratory system  Important in bone growth & repair Elastic  more flexible because of elastic fibers  External ear and larynx Fibrocartilage  very tough with many collagenous fibers  Shock absorbers-vertebral disks, knees, pelvis lacunae

Bone-(Osseous tissue) Characteristics  most rigid  collagen & mineral salts- calcium carbonate, calcium phosphate  good blood supply- heals rapidly structure  Osteocytes: make bone  haversian canals: concentric patterns around vessels-  Canniculi allow material to move through bone from vessles function  support body structures  protect vital organs  attachments for muscles  red marrow- forms red blood cells  stores and released inorganic salts

Types of Bone Compact bone  Forms dense part of bone Spongy bone  Filled with marrow

Blood cells suspended in a fluid ( blood plasma) structure  Red & white cells, platelets  form from hemopoietic tissues in bone marrow function  red cells- transport gasses white cells- fight infection, platelets- blood clotting

Muscle Tissue contractile tissue move body parts Types:  Skeletal muscle attach to bones, voluntary movement long cells up to 40 mm and narrow less than 0.1mm Striations & multi nucleated Nuclei cell striations

Types of muscle Smooth muscle  involuntary muscle  lack striations, short spindle shaped cells  Single nuclei centrally located  Walls of hallow organs: stomach, intestines, bladder, uterus, blood Vessels Cardiac Muscle  only found in the heart  Striated, branched interconnected cells  Single nucleus  Intercalated disc-intercellular junction  Involuntary contraction pumps blood through body

Nervous tissue  found in the brain, spinal cord, nerves  Neurons- highly specialized cell that detect changes and transmit Impulses  Neuroglial cells- support and bind the nervous tissue Carry out phagocytosis, supply nutrients from vessels, cell to cell communication

Membranes Simplest combination of tissues in the body to form a functional unit.  Epithelial membranes: linings of organs, cavities Cutaneous (skin) Serous: pericardium, pluerae (lung), peritoneum mucous: digestive, respiratory, reproductive  Synovial membranes: produce lubricating fluid for joints