Tissues

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Tissues

• Chapter 5

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4 Types of Tissues

• All tissues can be classified into four major
  categories based on structure and function
• Epithelial Covers and protect body surfaces,
  lines body cavities, moves substances in and out
  of blood (secretion, excretion absorption),
  form glands
• Connective support, connection, transport,
  protection
• Muscle moves the body its parts specialized
  for contractility
• Nervous provides communication between body
  parts and coordinates body functions

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Embryonic Development

• Zygote becomes a blastocyst through mitotic
  division
• Cells of the blastocyst regroup into primary germ
  layers
• Endoderm, mesoderm, ectoderm
• Gastrulation
• Histogenesis

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Epithelial Tissue

• Subdivided into 2 types
• Membranous
• Covers the body some of its parts
• Lines body cavities (pleural, pericardial,
  peritoneal), blood vessels, respiratory,
  digestive and genitourinary tracts
• Glandular
• Form the secretion units of the endocrine
  exocrine glands

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Epithelial Tissue

• Functions of epithelial tissues
• Protection
• Ex skin protects body from injury
  disease-causing micro-organisms
• Sensory
• Epithelial structures that specialize in sensory
  functions found in skin, nose, eye, ear
• Secretion
• Glandular epithelium secrete hormones, digestive
  juices sweat
• Absorption
• Ex gut absorbs nutrients exchange of
  respiratory gases
• Excretion
• Ex kidney tubules concentrate excrete urine
  and other waste products

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Epithelial Tissue

• Basement membrane
• Thin, noncellular layer of adhesive
• Connects epithelial tissue and underlying
  connective tissue
• Avascular
• without vascular
• Epithelial cells do not have blood vessels
• Oxygen nutrients diffuse from capillaries
  through connective tissue basement membrane to
  epithelial cells

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Classification of Membranous Epithelial Tissue

• Cell Shape
• Squamous flat, plate-like
• Cuboidal cube-shaped larger cytoplasm
• Columnar narrow and cylinder-shaped
• Pseudostratified single-layered all cells touch
  the basement membrane but may not extend to the
  top of the membrane
• Layers of Cells
• Simple single layer
• Stratified cells are layered on top of one
  another
• Transitional cell shape layers differ

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• Founds in areas where diffusion or filtration are
  necessary
• Examples of locations
• Alveoli (air sacs)
• Linings of blood lymphatic vessels
• Surfaces of pleura, pericardium peritoneum

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• Examples of locations
• Glands and their ducts

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• Examples of Locations
• Mucous membranes such as stomach, intestine,
  uterus
• Goblet cells (produce mucous) microvilli
  (increase surface area) are usually found on
  these cell types

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• Examples of locations
• Respiratory tract, male urethra
• Goblet cells cilia present

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• Examples of locations
• Skin
• Keratin (tough protein) provides (fig 5-8 not
  pictured)

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• Examples of locations
• Areas subject to stress and tension changes
  (Urinary bladder)

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Glandular Epithelium

• Specialized for secretory activity
• Unicellular glands
• Single celled
• Ex goblet cells
• Multicellular glands
• Function in clusters, solid cords or specialized
  follicles

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Endocrine vs Exocrine

• All glands are classified as endocrine or
  exocrine
• Exocrine glands
• Discharge/secrete into ducts
• Ex salivary glands
• Endocrine glands
• ductless glands
• Secrete hormones directly into blood or
  interstitial fluid
• Ex pituitary and thyroid glands

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Structural Classification of Exocrine Glands

• (Table 5-2, p. 133)
• Shape of gland
• Tubular
• Alveolar (sac-like)
• Complexity of gland
• Simple (one duct)
• Compound gt 2 ducts (branched)

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Functional Classification of Exocrine Glands

• Apocrine
• Collect secretory products at apex (tip)
• Apex of cell pinches off
• Cell repairs itself repeats process
• Ex milk-producing mammary glands
• Holocrine
• Collect secretory product inside the cell
• Rupture to release (self-destructs)
• Ex sebaceous glands (oil glands)
• Merocrine
• Discharge through plasma membrane
• This type applies to most exocrine glands
• Ex salivary glands

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Figure 5-12, p. 132
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Connective Tissue

• Most widespread tissue in the body
• Functions
• Connection
• Support
• Transport
• Protection
• Insulation

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Characteristics of Connective Tissue

• Common origin mesoderm
• Matrix
• Intercellular material
• Few cells, fibers, fluid, ground substance
  (material between cells)
• Fibers
• Collagenous fibers
• Reticular fibers
• Elastic fibers

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Fibers

• Collagenous fibers
• white fibers
• Made of collagen (fibrous protein)
• Tough, strong
• Reticular fibers
• Delicate
• Reticulin protein
• Support small structures (ex capillaries)
• Elastic fibers
• Extensible elastic
• Elastin protein
• Found in stretchy tissue (ex cartilage of the
  external ear)

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Classification of Connective Tissue

• Fibrous
• Loose (areolar)
• Adipose
• Reticular
• dense
• Bone
• Cartilage
• Hyaline
• Fibrocartilage
• elastic
• Blood

Reference Table 5-3, pp. 134-135
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Fibrous Connective Tissue

• Loose connective (areolar) tissue (fig 5-13)
• Stretchable
• most abundant connective tissue in the body
• Connects adjacent structures
• Ex btwn other tissues and organs
• Ex superficial fascia

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Fibrous Connective Tissue

• 2. Adipose tissue (fig 5-14)
• Contains mainly fat cells
• Supportive/protection pads around kidneys other
  body structures
• Storage deposit for excess food
• Insulating material, conserves body heat

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Fibrous Connective Tissue

• 3. Reticular Tissue (Fig 5-16)
• 3D web of reticular fibers
• Forms the framework of the spleen, lymph nodes
  bone marrow
• Meshwork filters harmful substances out of the
  blood

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Fibrous Connective Tissue

• 4. Dense Fibrous Tissue (fig 5-17, 5-18, 5-19)
• Densely packed fibers
• Regular Dense CT
• Fibers arranged in regular, parallel rows
• Collagen fibers
• Flexible, strong
• Tendons (muscle to bone) ligaments (bone to
  bone)
• Irregular Dense CT
• Fibers intertwine
• Withstand stress from any direction
• Ex dermis (inner layer of skin) outer capsule
  of kidney spleen

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Bone Tissue

• We will cover this when we cover the skeletal
  system
• Just know that bone is a type of connective
  tissue ?

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Cartilage

• Only 1 cell type chondrocyte
• Located in lacuna
• Avascular receive nutrients via diffusion
• Injuries to cartilage heal slowly due to poor
  nutrient delivery

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Cartilage - Types

• Hyaline cartilage
• Most common
• Covers ends of long bones (where joints
  articulate)
• Found in supporting rings of respiratory tubes
• Fibrocartilage
• Strongest, most durable
• Intervertebral disks
• Menisci in knee joint
• Elastic cartilage
• Fine elastic fibers
• High degree of flexibility
• External ear

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Blood

• Unusual type of connective tissue
• No ground substance
• Matrix plasma (55)
• Formed elements blood cells (45)
• Erythrocytes RBCs
• Leukocytes WBCs
• Thrombocytes platelets
• Transport function
• Respiratory gases, nutrients, waste products

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Muscle Tissue

• 3 types
• Skeletal muscle tissue
• Smooth muscle tissue
• Cardiac muscle tissue

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Skeletal Muscle Tissue

• Muscles (attached to bone)
• striated voluntary muscle
• Structure striations, multi-nucleated, long,
  tread-like cells, bundles of microfilaments

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Smooth Muscle Tissue

• Aka visceral muscle tissue
• Lines walls of hollow internal organs (viscera)
• Stomach, intestines, blood vessels
• non-striated involuntary muscle
• Structure long, narrow cells, non-striated

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Smooth Muscle Tissue
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Cardiac Muscle Tissue

• Walls of the heart
• striated involuntary muscle
• Structure striations, dark band (intercalated
  disks (where plasma membranes meet up)

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Nervous Tissue

• Rapidly integrates activities of various parts of
  the body
• Rapid communication is made possible b/c of the
  excitability conductivity characteristics of
  the nervous tissue

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Nervous System

• 3 Parts
• Brain
• Spinal cord
• Nerves

• Nervous Tissue
• Common origin ectoderm
• Two cell types
• Neurons (nerve cell)
• Neuroglia (supporting cells)

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Anatomy of Neurons

• Cell body soma
• Cell processes
• Axon ? transmits nerve impulses away from cell
  body
• Dendrites ? carry signals towards axon

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Tissue Repair

• After mechanical damage or tissue injury
• Phagocytic cells remove dead or injured cells
• Regeneration growth of functional new tissue
  (via mitotic division)
• Repair capacity based on tissue type

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Epithelial Connective Tissue Repair

• Greatest capacity to regenerate
• Epithelial Tissue
• Cut/injury ? cell division ? tissue regeneration
• Connective Tissue
• Cut/injury ? activation of cells that make
  collagen fibers ? injury site filled w/ dense
  fibrous CT
• Small injury dense fibrous CT replaced by
  normal tissue
• Deep/large injury dense fibrous CT forms scar

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Muscle Tissue Repair

• Limited repair capacity
• Damaged muscle tissue replaced with fibrous CT
• Results in loss of some or all ability to
  function normally

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Nervous Tissue Repair

• Limited ability to regenerate
• Some neurons outside the brain and spinal cord
  can regenerate (slow process)
• Majority of the time brain spinal injuries
  always result in permanent damage

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Body Membranes

• Membrane thin, sheet-like structure
• Two types
• Epithelial membranes
• Composed of epithelial tissue and underlying
  connective tissue
• Connective Tissues membranes
• Composed entirely of connective tissue

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Epithelial Membranes

• Cutaneous membrane
• Cover body surfaces exposed to external
  environment (skin)
• Serous membrane
• Single membrane covering two different surfaces
• Parietal membrane lines walls of body cavities
• Visceral membrane covers surface of organs
• Secrete thin, watery substance to prevent rubbing
• Mucous membrane
• Line body surfaces open to exterior
• Ex respiratory, digestive, urinary
  reproductive tracts

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Connective Tissue Membranes

• Synovial membranes
• Lines spaces between bones joints
• Secrete thick, colorless, lubricating fluid
  (synovial fluid)
• Fluid helps reduce friction btwn bone surfaces

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Mechanisms of Disease Tumors Cancer

• Neoplasm new matter (tumor)
• Abnormal growth of cells
• Benign Tumors
• Do no spread to other tissues
• Slow growth
• Encapsulated
• Usually not lethal unless interfere w/ organs

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Mechanisms of Disease Tumors Cancer

• Malignant tumors (cancer)
• Not encapsulated
• Spreads (metastasizes)
• Cancer cells spread via blood or lymphatic system
• Rapid growth/spread to nearby tissue

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(Known) Causes of Cancer

• Genetic Factors
• Inherited cancer genes oncogenes
• Tumor suppressor gene fails to operate
• Usually genetic predisposition coupled with
  cancer-causing mechanisms
• Ex breast cancer
• Carcinogens (cancer markers)
• Affect genetic activity ? abnormal cell
  reproduction
• Also called mutagens
• Ex chemicals, sun, viruses
• Age
• Some cancers arise based on age
• Ex leukemia (young) colon cancer (older adults)

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Detection of Cancer

• Self-examination
• Breast and testicular exams
• Medical Imagining
• X-ray
• Ex mammogram detection of breast cancer
• CT, MRI, ultrasound
• Produce cross-section of body images for tumor
  detection
• Blood tests
• Look for tumor markers (ex PSA)
• Biopsy
• Removal of tumor tissue

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Cancer Treatment Options

• Stage and grade cancer
• Helps determine outcomes
• Surgical removal (if possible)
• Could leave behind malignant cells
• Chemotherapy cytotoxic (cell-killing) drugs
• Destroys remaining malignant cells
• Radiation therapy
• Destructive x-ray or gamma radiation destroys
  cancer cells
• Immunotherapy
• Boosting immune system again viruses

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Anthonys Textbook of Anatomy and Physiology 17th
Edition. Thibodeau, Gary A. PhD and Patton, Kevin
T. PhD. Mosby, Inc.