Chapter 6 Tissues

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Chapter 6Tissues
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Principal Types of Tissue

• Four types of tissues
• I. Epithelial tissue
• II. Connective tissue
• III. Muscle tissue
• IV. Nervous tissue

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Extracellular Matrix (ECM)

• Functions
• Helps bind tissues together structurally
• Allows local communication among ECM and various
  cellsthrough connection via integrins in plasma
  membranes

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Extracellular Matrix (ECM)

• Components
• Water
• Proteins
• Structural proteins
• Collagenstrong, flexible protein fiber
• Elastinelastic fibers
• Includes glycoproteinsproteins with a few
  carbohydrate attachments
• Glycoprotein attachments also allow local
  communication within a tissue

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I. Epithelial Tissue

• Functions
• Protection
• Sensory functions
• Secretion
• Absorption
• Excretion

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I. Epithelial Tissue

• Types and locations
• Epithelium is divided into two types
• Membranous epitheliumcovers the body and some of
  its parts lines the serous cavities, blood and
  lymphatic vessels, and respiratory, digestive,
  and genitourinary tracts
• Glandular epitheliumsecretory units of endocrine
  and exocrine glands

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I. Epithelial Tissue

• Classification of epithelial tissue
• Classification based on cell shape
• Squamous
• Cuboidal
• Columnar
• Pseudostratified columnar

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I. Simple epithelium

• 1. Simple squamous epithelium
• One-cell layer of flat cells
• Permeable to many substances
• Examples endotheliumlines blood vessels
  mesotheliumpleura

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I. Simple epithelium

• 2. Simple cuboidal epithelium
• One-cell layer of cuboidal cells
• Found in many glands and ducts

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I. Simple epithelium

• 3. Simple columnar epithelium
• Single layer of tall, column-shaped cells
• Cells often modified for specialized
  functionse.g., goblet cells (secretion), cilia
  (movement), microvilli (absorption)
• Often lines hollow visceral structures

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I. Simple epithelium

• 4. Pseudostratified columnar epithelium
• Columnar cells of differing heights
• All cells rest on basement membrane but may not
  reach the free surface above
• Cell nuclei at odd and irregular levels
• Found lining air passages and segments of male
  reproductive system
• Motile cilia and mucus are important
  modifications

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I. Stratified epithelium

• 5.
• A. Stratified squamous (keratinized) epithelium
• Multiple layers of flat, squamous cells
• Cells filled with keratin
• Covers outer skin on body surface

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I. Stratified epithelium

• 5.
• B. Stratified squamous (nonkeratinized)
  epithelium
• Lines vagina, mouth, and esophagus
• Free surface is moist
• Primary function is protection

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I. Stratified epithelium

• 6. Stratified cuboidal epithelium
• Two or more rows of cells are typical
• Basement membrane is indistinct
• Located in sweat gland ducts and pharynx

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I. Stratified epithelium

• 7. Stratified columnar epithelium
• Multiple layers of columnar cells
• Only most superficial cells are typical in shape
• Rare
• Located in segments of male urethra and near anus

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I. Stratified epithelium

• 8. Stratified transitional epithelium
• Located in lining of hollow viscera subjected to
  stress (e.g., urinary bladder)
• Often 10 or more layers thick
• Protects organ walls from tearing

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Can you identify these?
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II. Connective Tissue

• Functions, characteristics, and types
• General functionconnects, supports, transports,
  and protects
• General characteristicsextracellular matrix
  (ECM) predominates in most connective tissues and
  determines its physical characteristics consists
  of fluid, gel, or solid matrix, with or without
  extracellular fibers (collagenous, reticular, and
  elastic) and proteoglycans or other compounds
  that thicken and hold together the tissue

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II. Connective Tissue

• Four main types
• 1.Fibrous
• A. Loose, ordinary (areolar)
• B. Adipose
• C. Reticular
• D. Dense
• Irregular
• Regular (collagenous and elastic)

2. Bone A. Compact bone B. Cancellous bone 3.
Cartilage A. Hyaline B. Fibrocartilage C.
Elastic 4. Blood
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1. Fibrous connective tissue

• A. Loose, ordinary (areolar) connective tissue
• One of the most widely distributed of all tissues
• Intercellular substance is prominent and consists
  of collagenous and elastic fibers loosely
  interwoven and embedded in soft, viscous ground
  substance
• Functionstretchy, flexible connection

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1. Fibrous connective tissue

• B. Adipose tissue
• Similar to loose connective tissue but contains
  mainly fat cells
• Functionsprotection, insulation, support, and
  food reserve

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1. Fibrous connective tissue

• C. Reticular tissue
• Forms framework of spleen, lymph nodes, and bone
  marrow
• Consists of network of branching reticular fibers
  with reticular cells overlying them
• Functionsdefense against microorganisms and
  other injurious substances reticular meshwork
  filters out injurious particles, and reticular
  cells phagocytose them

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1. Fibrous connective tissue D. Dense fibrous
tissue

• Matrix consists mainly of fibers packed densely
  and relatively few fibroblast cells
• Irregularfibers intertwine irregularly to form a
  thick mat (Figure 5-20)
• Regularbundles of fibers are arranged in
  regular, parallel rows
• Collagenousmostly collagenous fibers in ECM
  (Figure 5-21 and 5-22)
• Elasticmostly elastic fibers in ECM (Figure
  5-23)
• Locationscomposes structures that need great
  tensile strength, such as tendons and ligaments
  also dermis and outer capsule of kidney and
  spleen
• Functionfurnishes flexible connections that are
  strong or stretchy

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2. Bone tissue

• Highly specialized connective tissue type
• Cellsosteocytesembedded in a calcified matrix
• Inorganic component of matrix accounts for 65
  of total bone tissue
• Functions
• Support
• Protection
• Point of attachment for muscles
• Reservoir for minerals
• Supports blood-forming tissue

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A. Compact bone

• Osteon (Haversian system)
• Structural unity of bone
• Spaces for osteocytes called lacunae
• Matrix present in concentric rings called
  lamellae
• Canaliculi are canals that join lacunae with the
  central Haversian canal
• Cell types
• Osteocytemature, inactive bone cell
• Osteoblastactive, bone-forming cell
• Osteoclastbone-destroying cell
• Formation (ossification)
• In membranese.g., flat bones of skull
• From cartilage (endochondral)e.g., long bones,
  such as the humerus

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B. Cancellous bone

• Trabeculaethin beams of bone
• Supports red bone marrow
• Myeloid tissuea type of reticular tissue
• Produces blood cells
• Called spongy bone because of its spongelike
  appearance

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3. Cartilage

• Chondrocyte is only cell type present
• Lacunae house cells, as in bone
• Avasculartherefore, nutrition of cells depends
  on diffusion of nutrients through matrix
• Heals slowly after injury because of slow
  nutrient transfer to the cells
• Perichondrium is membrane that surrounds
  cartilage

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3. Types of Cartilage

• A. Hyaline
• Appearance is shiny and translucent
• Most prevalent type of cartilage
• Located on the ends of articulating bones
• B. Fibrocartilage
• Strongest and most durable type of cartilage
• Matrix is semirigid and filled with strong, white
  fibers
• Found in intervertebral disks and pubic symphysis
• Serves as shock-absorbing material between bones
  at the knee (menisci)
• C. Elastic
• Contains many fine, elastic fibers
• Provides strength and flexibility
• Located in external ear and larynx

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4. Blood

• A liquid tissue
• Contains neither ground substance nor fibers
• Composition of whole blood
• Liquid fraction (plasma) is the matrix55 of
  total blood volume
• Formed elements contribute 45 of total blood
  volume
• Red blood cells, erythrocytes
• White blood cells, leukocytes
• Platelets, thrombocytes

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4. Blood (cont.)

• Functions
• Transportation
• Regulation of body temperature
• Regulation of body pH
• White blood cells destroy bacteria
• Circulating blood tissue is formed in the red
  bone marrow by a process called hematopoiesis
  the blood-forming tissue is sometimes called
  hematopoietic tissue

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III. Muscle Tissue

• Types (Table 5-7)
• 1. Skeletal, or striated voluntary (Figure 5-32)
• 2. Smooth, or nonstriated involuntary, or
  visceral (Figures 5-33 and 5-34)
• 3.Cardiac, or striated involuntary (Figure 5-35)

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III. Muscle Tissue

• Microscopic characteristics
• 1. Skeletal musclethreadlike cells with many
  cross striations and many nuclei per cell
• 2. Smooth muscleelongated, narrow cells, no
  cross striations, one nucleus per cell
• 3. Cardiac musclebranching cells with
  intercalated disks (formed by abutment of plasma
  membranes of two cells)

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IV. Nervous Tissue

• Functionsrapid regulation and integration of
  body activities
• Specialized characteristics
• Excitability
• Conductivity
• Organs
• Brain
• Spinal cord
• Nerves

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IV. Nervous Tissue

• Cell types
• Neuronconducting unit of system
• Cell body, or soma
• Processes
• Axon (single process)transmits nerve impulse
  away from the cell body
• Dendrites (one or more)transmit nerve impulse
  toward the cell body and axon
• Neurogliaspecial connecting, supporting,
  coordinating cells that surround the neurons

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IV. Tissue Repair

• Tissues have a varying capacity to repair
  themselves damaged tissue regenerates or is
  replaced by scar tissue
• Regenerationgrowth of new tissue
• Scardense fibrous mass unusually thick scar is
  a keloid
• Epithelial and connective tissues have the
  greatest ability to regenerate
• Muscle and nervous tissues have a limited
  capacity to regenerate

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Body Membranes

• Thin tissue layers that cover surfaces, line
  cavities, and divide spaces or organs (Figure
  6-39, Table 6-8)
• Epithelial membranes are most common type (Figure
  6-40)
• Cutaneous membrane (skin)
• Primary organ of integumentary system
• One of the most important organs
• Composes approximately 16 of body weight

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Body Membranes

• Epithelial membranes (cont)
• Serous membrane (serosa)
• Parietal membranesline closed body cavities
• Visceral membranescover visceral organs
• Pleurasurrounds a lung and lines the thoracic
  cavity
• Peritoneumcovers the abdominal viscera and lines
  the abdominal cavity

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Body Membranes

• Epithelial membranes (cont)
• Mucous membrane (mucosa)
• Lines and protects organs that open to the
  exterior of the body
• Found lining ducts and passageways of the
  respiratory, digestive, and other tracts
• Lamina propriafibrous connective tissue
  underlying mucous epithelium
• Mucus is made up mostly of water and
  mucinsproteoglycans that form a double-layer of
  protection against environmental microbes (Figure
  6-41)

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The Big Picture Tissues, Membranes, and the
Whole Body

• Tissues and membranes maintain homeostasis
• Epithelial tissues
• Form membranes that contain and protect the
  internal fluid environment
• Absorb nutrients
• Secrete products that regulate functions involved
  in homeostasis
• Connective tissues
• Hold organs and systems together
• Form structures that support the body and permit
  movement

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The Big Picture Tissues, Membranes, and the
Whole Body

• Tissues and membranes maintain homeostasis
• Epithelial tissues
• Form membranes that contain and protect the
  internal fluid environment
• Absorb nutrients
• Secrete products that regulate functions involved
  in homeostasis
• Connective tissues
• Hold organs and systems together
• Form structures that support the body and permit
  movement

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The Big Picture Tissues, Membranes, and the
Whole Body

• Tissues and membranes maintain homeostasis (cont)
• Muscle tissues
• Work with connective tissues to permit movement
• Nervous tissues
• Work with glandular epithelial tissues to
  regulate body function

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