Copyright 2010, John Wiley & Sons, Inc. Chapter 4 Tissues.

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Chapter 4Tissues

Tissues 4 basic types:

Epithelial Connective Muscular Nervous

Epithelial Tissue Cells lie close together in continuous sheets

with little extracellular material Cover surfaces and line cavities; always a free

(apical) surface Forms glands

Basement membrane of connective tissue Has no blood vessels (avascular) Has a nerve supply Has a high capacity for cell division

Categories- Table 4.1

Arrangement of cells in layers Simple: 1 layer of cells Stratified: more than 1 layer of cells

Cell Shapes Squamous - flat Cuboidal - squares Columnar - rectangle Transitional - change shape

Simple Squamous Epithelium Single layer flat cells Important for filtration (kidneys) or diffusion

(lungs, capillaries) Called endothelium when lining heart, blood

and lymphatic vessels Called mesothelium when in serous

membranes

Simple Cuboidal Epithelium• Cube shaped cells • Rounded nuclei• function in secretion & absorption in kidneys• cover ovaries• function in secretion in glands

Simple Columnar Epithelium cilated or noncilated• all nuclei near basement membrane• intestine - microvilli

• increases surface area for absorption• often have goblet cells – secrete mucus• line uterus, stomach, etc. – protects underlying tissues,

secretes digestive fluids, & absorbs nutrients

Pseudostratified Columnar Appears stratified; nuclei at various levels• often have cilia & goblet cells – line & sweep debris

from respiratory tubes• female reproductive tract cilia aid in moving eggs

Stratified Squamous Epithelium Apical layer cells are flat Deep layers vary from cuboidal to columnar Cells in basal layer divide and move upward

toward apical surface Found in areas of surface wear and tear

Stratified Squamous Epithelium• protect underlying layers• can accumulate keratin in outer layer• outer layer of skin• line oral cavity (mouth), throat, vagina, and anal canal

Stratified Cuboidal Epithelium Rare 2-3 layers of cube-shaped cells line ducts of mammary glands, sweat glands, salivary glands, and the pancreas Several layers provide greater protection

Stratified Columnar Epithelium Rare top layer elongated cells cube-shaped cells in deeper layers line vas deferens, male urethra, and part of pharynx

Transitional Epithelium cells can stretch cube-shaped and elongated cells Designed to distend & return to normal size line urinary bladder, ureters, and part of urethra

Glandular Epitheliumcells that are specialized to produce and secrete substancesEndocrine glands are ductlessExocrine glands have ducts

Unicellular•composed of one cell (goblet cell)Multicellular• composed of many cells• sweat glands, salivary glands, etc.

Structural Types of Exocrine Glands

Types of Glandular SecretionsMerocrine glands

• fluid product - exocytosis• salivary glands• pancreas•sweat glands

Apocrine glands • cellular product• portions of cells• mammary glands• ceruminous glands

Holocrine glands• secretory products• whole cells• sebaceous glands

Connective Tissue Most abundant tissue type typically found between other tissues Small cells far apart with large amount of

extracellular material (matrix) Has good blood supply

exception: cartilage - avascular

Connective Tissue Cells Fibroblasts:

Secrete fibers Macrophages:

Engulf bacteria and cell debris - phagocytosis Plasma cells:

Make antibodies

Connective Tissue Cells Mast cells:

Part of an inflammatory reaction: produce histamine - dilates blood vessels

Adipocytes: fat cells energy provide protection

Extracellular Matrix Fluid, gel or solid + protein fibers found between cells and fibers Fibers: 3 types

Collagen fibers: very strong and flexible Elastic fibers: smaller stretch and return to

original length Reticular fibers: provide support and strength

Found in basement membranes

Loose Areolar Connective Tissue• mainly fibroblasts• fluid to gel-like matrix• collagenous fibers• elastic fibers• bind skin to structures•beneath most epithelia•between muscles

Adipose Tissue• cushions• insulates• store fats• beneath skin• behind eyes• around kidneys and heart

Reticular Connective Tissue composed of reticular fibers supports walls of liver, spleen, lymphatic organs

Dense Regular Connective Tissue• packed collagenous fibers• elastic fibers• few fibroblasts• bind body parts together• tendons, ligaments, dermis• poor blood supply

Elastic Connective Tissue• abundant in elastic fibers• some collagenous fibers• fibroblasts• attachments between vertebrae• walls of large arteries, airways, heart

Cartilage Dense network of collagen and elastic fibers Stronger than dense fibrous connective tissue Cells: chondrocytes

Very few; occur singularly or in groups Found in spaces called lacunae

Has no blood vessels or nerves rigid matrix

Classification: Cartilage Types

Hyaline: Fibrocartilage: Elastic:

Hyaline Cartilageappears clear because fibers are not easily visible

• most abundant• ends of bones• nose, respiratory passages• embryonic skeleton

Fibrocartilage fibers visible

Strongest typeshock absorber

• intervertebral discs• pads of knee and pelvic girdle

Elastic Cartilage chondrocytes in threadlike elastic network

• flexible• external ear, larynx

Bone: Osseous Tissue Forms most of the skeleton Supports, protects, and allows movements site of blood formation and storage of

minerals Solid matrix made rigid by calcium and

phosphorus salts osteocytes (mature bone cell) in lacunae

(hollow space)

Liquid Connective Tissue Blood: found within blood vessels

Matrix is plasma (fluid) Cells: red blood cells, white blood cells, platelets

transports defends clotting

Liquid Connective Tissue Lymph: found within lymph vessels

Matrix is lymph: similar to plasma but with much less protein

Some white blood cells

Body Membranes: Four Types1. Mucous membranes: line body cavities

and passageways open to the exterior Secrete mucus

2. Serous membranes: line closed cavities and surrounds organs located there

Serous fluid reduces friction Parietal and visceral layers Pleura, pericardium, peritoneum

3. Synovial membranes: line cavities of most joints

Made of connective tissues (no epithelium) Secrete synovial fluid that reduces friction

and lubricates and nourishes cartilage

4. Cutaneous membranes: skin (chapter 5)

Body Membranes: Four Types

Muscular Tissue Functions

Produce movements, release heat Cells

Elongated, contractile (called muscle fibers) ThreeTypes

Skeletal muscle: Cardiac muscle: Smooth muscle:

Skeletal Muscle attached to bones

striated voluntary

Smooth Muscle walls of organs skin walls of blood

vessels involuntary not striated

Cardiac Muscle

Intercalated disks Striated Not voluntary

Nervous Tissue Functions: conduct nerve impulses Types of cells

Neurons: convert stimuli into nerve impulses and conduct them

Neuroglia: do not generate nerve impulses, but serve supportive functions

• found in brain, spinal cord, and peripheral nerves

• sensory reception

Tissue Repair Epithelial cells originate from stem cells in

defined areas of tissue layer Bone regenerates readily, cartilage poorly Muscular tissue can replace cells but slowly Nerve tissue is poorest at replacement

although some stem cells seem to be available

Replacement scar tissue with functional loss.

Tissue and Organ Sourcing

Histocompatability: ABO/Rh; HLA (Human Leukocyte Antigens)

1. Autograft (Autologous) – Auto = self• Use your own tissue• No rejection

2. Isograft (Isologous) – Iso = equal• Use tissue from an identical twin• First Kidney Transplant – Dec 23, 1954

3. Allograft (Allogenic) – Allo = Different Use tissue from a different person Rejection – may need immunosuppression

4. Xenograft (Xenologous) – Xeno = Foreign

• Use tissue from a different species

5. Biocompatible/Biodegradable material – inert = not rejected (no immune response)

• Plastic, titanium, aluminum, gortex• Used as scaffold in tissue engineering• 1938 – Growing organs in laboratory

What causes rejection? Immune Response: Host v. Graft – most rejections

Host rejects the transplanted tissue Graft v. Host – some rejections

Transplanted tissue rejects the host GVHD (Graft Versus Host Disease)

Bone marrow transplants/Face transplants

Donor Cell or Tissue Sources: Donation Stem Cells –

Embryonic Stems/Adult Stems iPS (induced Pluripotent Stem – made from skin)

Clinical ApplicationCollagen Disorders

Chondrodysplasia• collagen chains too wide• stunted growth• deformed joints

Dystrophic epidermolysis bullosa• breakdown of collagen that attaches skin layers• stretchy skin• lax joints

Hereditary osteoarthritis• change in amino acid in collagen• painful joints

Copyright 2010, John Wiley & Sons, Inc. Chapter 4 Tissues.

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