Connective Tissue Types

TISSUES

1 Introduction

• Similar cells with a common function are called tissues.

• The study of tissues is called histology. • There are four (4) primary or major tissue types: 1. Epithelial Tissue 2. Connective Tissue 3. Muscle Tissue 4. Nervous Tissue 2 Intercellular Junctions

Tight junctions Cell membrane • Close space between cells

• Located among cells that Tight junction form linings Cell membrane Desmosomes • Form “spot welds” between cells • Located among outer skin cells Desmosome Gap junctions Cell membrane • Tubular channels between cells • Located in cardiac muscle cells Gap junction

3 Epithelial Tissue

• General characteristics: • Cover organs and the body • Line body cavities • Line hollow organs • Have a free surface • Have a basement membrane • Are avascular • Cells readily divide • Cells tightly packed • Cells often have desmosomes • Function in protection, secretion, absorption, and excretion • Classified according to cell shape and number of cell layers 4 Epithelial Tissue

• Simple squamous: • Simple cuboidal: • Single layer of flat cells • Single layer of cube-shaped cells • Substances pass easily through • Line kidney tubules • Line air sacs • Cover ovaries • Line blood vessels • Line ducts of some glands

• Line lymphatic vessels

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Nucleus Simple squamous Basement epithelium membrane Basement Free surface of tissue

Nucleus Simple cuboidal epithelium Connective Connective tissue tissue (a) (b) (a) (b)

b,d: © Ed Reschke b: © The McGraw-Hill Companies, Inc./Al Telser, photographer

5 Epithelial Tissue

• Simple columnar: • Pseudostratified columnar: • Single layer of elongated cells • Single layer of elongated cells • Nuclei usually near the basement • Nuclei at two or more levels • Membrane at same level • Appear striated • Sometimes possess cilia • Often have cilia • Sometimes possess microvilli • Often have goblet cells • Often have goblet cells • Line respiratory passageways

Mucus Goblet cell Nucleus

Cytoplasm Nucleus

Basement Microvilli membrane (free surface of tissue) Connective tissue Goblet cell (a) (b)

Basement membrane

Connective b: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer tissue (a) (b)

6 b: © The McGraw-Hill Companies, Inc./Al Telser, photographer. Epithelial Tissue

• Stratified squamous: • Stratified cuboidal: • Many cell layers • 2-3 layers • Top cells are flat • Cube-shaped cells • Can accumulate keratin • Line ducts of mammary glands, • Outer layer of skin sweat glands, salivary glands, and • Line oral cavity, vagina, and the pancreas anal canal

Free surface of tissue Stratified cuboidal epithelium

Squamous Nucleus cells Lumen Free surface of tissue Basement membrane Connective tissue (a) (b)

Layer of dividing cells

Basement membrane b: © The McGraw-Hill Companies, Inc./Al Telser, photographer.

Connective tissue 7 (a) (b)

b: © The McGraw-Hill Companies, Inc./Al Telser, photographer Epithelial Tissue

• Stratified columnar: • Transitional: • Top layer of elongated cells • Many cell layers • Cube-shaped cells in deeper • Cube-shaped and elongated layers cells • Line part of male urethra and • Line urinary bladder, part of pharynx ureters, and part of urethra

Lumen Basement Free surface membrane of tissue Stratified Underlying columnar connective tissue epithelium (a) (b)

Basement membrane Free surface Connective of tissue tissue Stretched transitional epithelium (a) (b) Basement membrane Underlying connective tissue b: © The McGraw-Hill Companies, Inc./Al Telser, photographer

• Composed of cells that are specialized to produce and secrete substances

• There are two (2) types: • Endocrine glands are ductless (key word: hormone) • Exocrine glands have ducts • Unicellular exocrine gland: • Composed of one cell • Goblet cell • Multicellular exocrine gland: • Composed of many cells • Sweat glands, salivary glands, etc. • Simple and compound 9 Structural Types of Exocrine Glands

Tissue surface Duct

Secretory portion

Simple tubular Simple branched Simple coiled Simple branched tubular tubular alveolar

Compound tubular Compound alveolar 10 Types of Glandular Secretions

• Merocrine Glands • Apocrine Glands • Holocrine Glands • Fluid product • Cellular product • Secretory products • Salivary glands • Portions of cells • Whole cells • Pancreas gland (?) • Mammary glands • Sebaceous glands • Sweat glands • Ceruminous glands •Serous Fluid Pinched off Disintegrating cell •Mucus portion of cell and its contents Intact (secretion) (secretion) cell Secretion

New cell forming by mitosis and cytokinesis

(a) Merocrine gland (b) Apocrine gland (c) Holocrine gland 11 Connective Tissues

• General characteristics: • Most abundant tissue type • Many functions: • Bind structures • Provide support and protection • Serve as frameworks • Fill spaces • Store fat • Produce blood cells • Protect against infections • Help repair tissue damage • Have an extracellular matrix • Have varying degrees of vascularity

• Have cells that usually divide 12 Connective Tissue Major Cell Types Present

• Fibroblasts • Macrophages • Fixed cell • Wandering cell • Most common cell • Phagocytic • Large, star-shaped • Important in injury or • Produce fibers infection

• Mast cells • Fixed cell • Release heparin • Release histamine

13 Connective Tissue Fiber Types Present • Collagenous fibers • Elastic fibers • Thick • Bundles of microfibrils • Composed of collagen embedded in elastin • Great tensile strength • Fibers branch • Abundant in dense CT • Elastic • Hold structures together • Vocal cords, air passages • Tendons, ligaments • Reticular fibers • Very thin collagenous fibers • Highly branched • Form supportive networks 14 Connective Tissues

• Connective Tissue Proper: • Specialized Connective Tissue: • Loose connective tissue • Cartilage • Adipose tissue • Bone • Reticular connective tissue • Blood • Dense connective tissue • Elastic connective tissue

15 Connective Tissue Types

• Loose Connective Tissue • Adipose Tissue • Mainly fibroblasts • Adipocytes • Fluid to gel-like matrix • Cushions • Collagenous fibers • Insulates • Elastic fibers • Store fats • Bind skin to structures • Beneath skin • Beneath most epithelia • Behind eyeballs • Blood vessels nourish • Around kidneys and heart nearby epithelial cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Between muscles Cytsol

Collagenous Cell fiber membrane

Fibroblast Nucleus

Ground (a) (b) substance

Elastic fiber b: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer (a) (b) 16

b: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer Connective Tissue Types

• Reticular Connective Tissue • Dense Connective Tissue • Composed of reticular fibers • Packed collagenous fibers • Supports internal organ walls • Elastic fibers • Walls of liver, spleen, • Few fibroblasts lymphatic organs • Bind body parts together • Tendons, ligaments, dermis • Poor blood supply

Fibroblasts Collagenous fibers Collagenous fibers

White blood (a) (b) cell

Fibroblast

(a) (b) b: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer

b: © The McGraw-Hill Companies, Inc./Al Telser, photographer 17 Connective Tissue Types

• Elastic Connective Tissue • Bone (Osseous Tissue) • Abundant in elastic fibers • Solid matrix • Some collagenous fibers • Supports • Fibroblasts • Protects • Attachments between bones • Forms blood cells • Walls of large arteries, airways, heart • Attachment for muscles • Skeleton • Osteocytes in lacunae Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display

Collagenous fibers Osteon

Lamella

Fibroblast

Central Elastic fibers canal

Osteocyte in lacuna

(a) (b) Canaliculi

(a) (b) b: © The McGraw-Hill Companies, Inc./Al Telser, photographer

Osteocyte

Nucleus Cell process in canaliculus 1821 b: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer Connective Tissue Types

• Hyaline cartilage • Most abundant • Ends of bones • Nose, respiratory passages • Cartilage • Embryonic skeleton • Rigid matrix • Chondrocytes in lacunae • Elastic cartilage • Poor blood supply • Flexible • Three (3) types: • External ear, larynx • Hyaline Cartilage • Elastic Cartilage • Fibrocartilage • Fibrocartilage • Very tough • Shock absorber • Intervertebral discs • Pads of knee and pelvic girdle 19 Connective Tissue Types

Three (3) types of cartilage:

Elastic fibers

Nucleus Nucleus Lacuna Lacuna

Chondrocyte Chondrocyte

Extracellular matrix Extracellular (a) (b) matrix (a) (b)

b: © The McGraw-Hill Companies, Inc./Al Telser, photographer b: © The McGraw-Hill Companies, Inc./Al Telser, photographer

Hyaline Cartilage Elastic Cartilage

Lacuna Chondrocyte

Nucleus

Collagenous fiber

Extracellular matrix

(a) (b)

• Blood • Fluid matrix called plasma • Red blood cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. White blood • White blood cells cell Red blood • Platelets cells Plasma (extracellular • Transports matrix of blood)

• Defends Platelets • Involved in clotting (a) (b) • Throughout body in blood b: © The McGraw-Hill Companies, Inc./Al Telser, photographer vessels • Heart

21 Types of Membranes • There are four (4) types of epithelial membranes: 1. Serous Membranes 2. Mucous Membranes • Line body cavities that • Line tubes and organs do not open to the that open to outside world outside • Lining of mouth, nose, • Reduce friction throat, etc. • Inner lining of thorax • Secrete mucus and abdomen 3. Cutaneous Membranes • Cover organs of thorax • Covers body and abdomen • Skin • Secrete serous fluid 4. Synovial Membranes • Composed entirely of connective tissue • Lines joints 22 Muscle Tissues

• Skeletal muscle • Attached to bones • Striated • General characteristics: • Voluntary • Muscle cells also called muscle fibers • Smooth muscle • Contractile • Walls of organs • Three (3) types: • Skin • Skeletal muscle • Walls of blood vessels • Smooth muscle • Involuntary • Cardiac muscle • Non-striated • Cardiac muscle • Heart wall • Involuntary • Striated • Intercalated discs 23 Muscle Tissue

Striations Cytoplasm

Nuclei Nucleus

Portion of a muscle fiber

(a) (b) (a) (b)

b: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer b: © The McGraw-Hill Companies, Inc./Al Telser, photographer

Skeletal Muscle Smooth Muscle

Striations

Nucleus

Intercalated disc

(a) (b)

• Found in brain, spinal cord, and peripheral nerves

• Functional cells are neurons Cellular process

Cytoplasm

• Neuroglial cells support and Nucleus

Cell bind nervous tissue components membrane

Neuroglial cells • Sensory reception (a) (b)