Chapter 5 Tissues Tissues Tissues - groups of cells that are similar in structure & function RBC, WBC, & platelets are a group of cells working together to form BLOOD tissue Histology Pathohistology study of diseased tissues 4 Types of Body Tissues Tissues are groups of cells with similar structure & function 4 primary types Epithelium Connective tissue Muscle Nervous tissue 1
Epithelial Tissues Found in different areas Body coverings Body linings Glandular tissue Functions Protection Absorption Filtration Secretion Epithelium Characteristics Cells fit closely together Always has 1 free surface Lower surface is bound by a basement membrane (non-living) Avascular no blood supply Diffusion Regenerate easily if well nourished Classification of Epithelium Based on # of layers & shape # of cell layers Simple 1 layer Stratified more than 1 layer 2
Classification of Epithelium Shape of cells Squamous flattened Cuboidal cube shaped Columnar tall, slender cells Simple Epithelium Simple squamous Single layer of flat cells Nucleus usually oblong Site of diffusion & filtration Usually forms membranes Lines body cavities - lungs & capillaries Simple Epithelium Simple cuboidal Single layer of cube cells Spherical nucleus Common in glands & ducts Forms walls of kidney ureters Covers ovaries 3
Simple Epithelium Simple columnar Single layer of tall cells Nucleus near basement membrane Sometimes ciliated (uterine tube) Lines digestive tract Often includes goblet cells, which produce mucus Simple Epithelium Pseudostratified Single layer, but some cells are shorter than others Looks like a double cell layer with nucleus is various layers Sometimes ciliated, (respiratory tract) May function in absorption or secretion Stratified Epithelium Stratified squamous Cells at the free edge are flattened; basement cuboidal or columnar Protective covering where friction is common Locations Skin Mouth Esophagus Accumulates as keratin 4
Stratified Epithelium Stratified cuboidal - 2 layers of cuboidal cells that forms a lumen Sweat, salivary & mammary glands Stratified columnar - surface cells are columnar, cells underneath vary in size & shape Line vas deferens, male urethra, & part of pharynx Stratified Epithelium Transitional epithelium Stratified; begins as cuboidal and flatens as cells fill Shape of cells depends upon the amount of stretching Lines Bladder & Uterus Glandular Epithelium Cells that secretes a particular product 2 major gland types Endocrine gland Ductless Secrete into blood or a tissue EX. hormones Exocrine gland Empty through ducts to the outside surface Ex. sweat & oil glands 5
Exocrine glandular secretions Classified by the way they secrete products Merocrine release fluids by exocytosis; EX. Saliva, sweat, pancreatic glands Apocrine secrete small portions of cell bodies EX. Mammary & cerumin Holocrine release entire cells EX. sebaceous Goblet Cells Cells present in epithelial tissues that secrete mucus Epithelial Tissue Summary Table 5.5 page 161 6
Connective Tissue The most abundant & widely distributed tissues Functions Binds tissues together Supports the body Provides protection Stores fat Produces blood Repairs tissues Connective Tissue Characteristics More loosely arranged than epithelial Vary in blood supply Some well vascularized & others are avascular Extracellular matrix between cells Non-living material that surrounds living cells; contains proteins & chemicals necessary for life Connective Tissue Cell Types Fixed cells reside in tissue a long time Fibroblast Most common Star shaped cells that produce protein fibers *next slide Mast cells Large cells near blood vessels Releases heparin prevents blood clotting Releases histamines promotes allergies, hay fever & inflammation Macrophages Phagocytosis WBC s that clean up foreign materials & debris 7
Connective Tissue Fibers Fibroblast fixed cells that secrete protein fibers 3 types Collagen fibers thick strands with some flexibility; bind structures together Dense connective tissues EX. Ligaments & tendons Elastic fibers weaker than collagen but more flexible; easily stretched & return to original shape Ex. vocal cords, aorta, blood vessels Reticular fibers thin, delicate branching fibers EX. Spleen, lymph nodes Connective Tissue Categories Loose connective tissues Areolar Adipose Reticular Dense connective tissues Dense regular Dense irregular Elastic Specialized Cartilage Bone Blood Types of Connective Tissue Areolar connective tissue Most widely distributed connective tissue Soft, pliable tissue that cushions organs & binds them to skin Has fibroblast, elastic and collagen fibers 8
Connective Tissue Types Adipose tissue (fat) Nucleus pushed to side Functions Insulates the body Protects, cushions organs Reserve fuel storage Connective Tissue Types Reticular connective tissue Delicate network of reticular fibers Forms lymphoid organs Lymph nodes Spleen Bone marrow Types of Connective Tissue Dense Regular Connective tissue Mostly collagen fibers Fibroblast cells Tightly packed waves Poor blood supply Ex. Tendon Ligaments 9
Types of Connective Tissue Elastic Connective Many elastic fibers Some collagen & fibroblast Locations: attachment between vertebrae, wall of large arteries, airways Collagenous fibers Elastic fibers Cartilage Cartilage rigid connective tissues Poor blood supply Chondrocytes 3 types of cartilage Hyaline cartilage Elastic cartilage Fibrocartilage Types of Connective Tissue Hyaline cartilage Most common cartilage Composed of: Chondrocytes lie in lacunae (cavity) Fine collagen fibers Rubbery matrix End of long bones, fetal skeleton, nose, trachea, ribs 10
Types of Connective Tissue Elastic cartilage Chondrocytes lie in lacunae More elastic fibers present; more flexible Provides elasticity EX. External ear Elastic fibers Nucleus Lacuna Chondrocyte Extracellular matrix (b) Types of Connective Tissue Fibrocartilage Highly compressible; shock absorber Thick collagen fibers Ex: discs between vertebrae, meniscus of knee Chondrocyte Collagenous fiber (b) Types of Connective Tissue Bone (Osseous) Protect & support the body Hematopoiesis Composed of: Bone cells (osteocytes) in lacunae Hard matrix of Ca salts 11
Bone Cell Structures Osteon bone unit Lamella Central canal nerve and blood flow in center of osteon Osteocyte Canaliculi connects cells to each other See Fig. 5.26 page 170 Osteon Lamella Central canal Osteocyte in lacuna Canaliculi Osteocyte Nucleus Canaliculus (c) Connective Tissue Types Blood RBC & WBC Blood cells surrounded by fluid matrix (plasma) Fibers visible during clotting (platelets) Functions Transport materials Fights infections Clotting 12
Connective Tissue Summary Table 5.7 page 171 Types of Membranes There are 4 types of epithelial membranes: 1. Serous Membranes Line body cavities that do not open to the outside Reduce friction Inner lining of thorax and abdomen Cover organs of thorax and abdomen Secrete serous fluid lubricates 3. Cutaneous Membranes Covers body Skin 2. Mucous Membranes Line tubes and organs that open to outside world Lining of mouth, nose, throat, etc. Secrete mucus 4. Synovial Membranes Composed entirely of connective tissue Lines joints Muscle Tissue Function in movement Contractile tissues 3 types Skeletal muscle Cardiac muscle Smooth muscle 13
Muscle Tissue Types Skeletal muscle Voluntarily controlled Cells usually attached to bone Striations Multinucleated Long, cylindrical Stimulated by nerve cells Muscle Tissue Types Cardiac muscle Only in the heart Involuntary Cells attached to other cardiac muscle cells at intercalated disks Striated cells 1 nucleus/cell Branches Muscle Tissue Types Smooth muscle Involuntary Surrounds hollow organs No striations 1 nucleus per cell Spindle shape 14
Nervous Tissue Neurons - nerve cells Sends impulses to all areas of the body Axon - Dendrite Neuroglia support neurons 15