How do cells form tissues

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How do cells form tissues?

• Tissues

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Using cell junctions
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Tissues

• Epithelial tissue
• Connective tissue
• Muscle tissue
• Nervous tissue

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Epithelial Tissue

• Closely packed cells in continuous sheets
  connected by many desmosomes tight junctions
• Apical and Basal surfaces
• Cells rest on Basement membrane
• No blood supply, depend on diffusion from
  capillaries for food and oxygen

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Apical vs. Basal

• APICAL SURFACE
• A free surface or edge exposed to the bodys
  exterior or to the cavity/lumen of an internal
  organ.

• BASAL SURFACE
• Basement membrane
• Lower surface of epithelium
• Structureless material secreted by the cells

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Types of Epithelial Tissue

• SIMPLE
• Squamous
• Cuboidal
• Columnar
• Pseudostratified

• STRATIFIED
• Squamous
• Cuboidal
• Columnar
• Transitional

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Simple vs. Stratified

• Simple epitheliaone layer of cells
• Concerned with absorption, secretion, and
  filtration
• Stratified epitheliatwo or more cell layers
• More durable
• Function primarily to protect

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Simple Squamous Epithelium

• Single layer of thin squamous cells resting on a
  basement membrane
• Substances move by rapid diffusion or filtration
• Ex. Walls of capillaries, air sacs of lungs

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Simple Cuboidal Epithelium

• One layer of cuboidal cells resting on a basement
  membrane
• Common in glands and ducts
• Ex. Salivary glands, covers surface of ovaries

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Simple Columnar Epithelium

• 1. Made up of a single row of elongated cells
  whose nuclei are all located near the basement
  membrane.
• 2. It lines the uterus, stomach, and intestines
  where it protects underlying tissues, secretes
  digestive fluids, and absorbs nutrients.
• 3. In the intestine, these cells possess
  microvilli that increase the surface area
  available for absorption.
• 4. Mucus-secreting goblet cells can be found
  among columnar cells.

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• 1. These cells appear layered due to the varying
  positions of their nuclei within the row of
  cells, but are not truly layered.
• 2. Cilia may be present, along with
  mucus-secreting globlet cells, that line and
  sweep debris from respiratory tubes.
• 3. In the female reproductive tract, cilia on
  these cells aid in moving eggs through the
  oviducts to the uterus.

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Stratified Squamous

• 1. This type of tissue is made up of layers of
  flattened cells that are designed to protect
  underlying layers.
• 2. It makes up the outer layer of skin, and lines
  the mouth, throat, vagina, and anal canal.
• 3. In the skin, outer layers of cells undergo
  keratinization however, this process does not
  occur where tissues remain moist in the throat,
  vagina, or anal canal.

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Stratified Cuboidal

• 1. This tissue consists of two to three layers of
  cuboidal cells lining a lumen of the mammary
  glands, sweat glands, salivary glands, and
  pancreas.
• 2. Several layers of cells provide greater
  protection than one single layer.

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Stratified Cuboidal
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Stratified Columnar

• 1. This tissue consists of several layers of
  cells and is found in the vas deferens, part of
  the male urethra, and parts of the pharynx.

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Stratified Columnar
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Transitional

• 1. Transitional epithelium is designed to distend
  and return to its normal size, as it does in the
  lining of the urinary bladder.
• 2. This design provides distensibility and keeps
  urine from diffusing back into the internal
  cavity.

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Glandular Epithelium

• Endocrine Glands
• Lose their connection to the surface (ductless
  glands)
• Secretions (all hormones) diffuse directly into
  blood vessels
• Ex. Thyroid, adrenals, pituitary

• Exocrine Glands
• Retain their ducts, secretions empty through
  ducts to epithelial surface
• Ex. Sweat and oil glands, liver, pancreas

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What are glands?

• Glands--Consist of one or more cells that make
  and secrete a particular product.
• Secretiontypically contain protein molecules in
  an aqueous (water-based) fluid
• Glandular cells obtain needed materials from the
  blood and use them to make their secretion, which
  then get discharge

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Connective Tissue
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Characteristics of Connective Tissue

• Function primarily in protecting, supporting, and
  binding together other body tissues
• Most are well vascularized except tendons,
  ligaments and cartilage.
• Extracellular matrixproduced by connective
  tissue cells and secreted to the exterior
• Liquid, semisolid (gel-like), or very hard
• Weight bearing, withstand stretching, and other
  abuses

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Characteristics Continued

• Fibersmade by CT cells and secreted
• Collagen fibers (white)
• Elastic fibers (yellow)
• Reticular fibers (fine collagen)

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Types of Connective Tissue

• From most rigid to softest
• Bone
• Cartilage
• Dense connective tissue
• Loose connective tissue
• Blood

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Bone

• Osseus tissue
• Most rigid connective tissue, with deposits of
  mineral salts and collagen within the matrix.
• Bone cells, called osteocytes, lie within lacunae
  and are arranged in concentric circles
• Good blood supply, enabling rapid recovery after
  an injury.
• Rocklike hardness allows protection and support
  of other body organs

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Cartilage

• Provides a supportive framework for various
  structures.
• Cartilage cells (chondrocytes) lie within lacunae
  in the gel-like fluid matrix.

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Types of Cartilage

• Hyaline cartilage is white with abundant fine
  collagen fibers, is found at the ends of bones,
  and supports respiratory passages.
• Elastic cartilage, with elastic fibers, provides
  a framework for the external ears and parts of
  the larynx.
• Fibrocartilage is a tough tissue that provides a
  shock-absorbing function in intervertebral disks
  and in the knees and pelvic girdle.

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Dense Connective Tissue

• This tissue consists of densely packed
  collagenous fibers and is very strong but lacks a
  good blood supply.
• Fibroblastscells that make fibers
• It is found as part of tendons and ligaments.

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Loose Connective Tissue

• This type of tissue forms delicate, thin
  membranes throughout the body that bind body
  parts together.
• Fibroblasts are separated by a gel-like ground
  substance that contains collagenous and elastic
  fibers.
• It binds the skin to underlying organs and fills
  spaces within muscle.

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Areolar Tissue

• Most widely distributed connective tissue in the
  body
• Cusions and protects body organs it wraps
• Glue that holds internal organs together

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Adipose Tissue

• Fat storing connective tissue
• Found beneath the skin (insulates the body),
  around joints, padding the kidneys and other
  internal organs, and in certain abdominal
  membranes.

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Reticular Connective Tissue

• Network of interwoven reticular fibers associated
  with reticular cells
• Internal supporting framework

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Blood

• Blood is composed of cells (red and white)
  suspended in a fluid matrix (plasma).
• It is formed in the blood-forming tissues inside
  red bone marrow and functions to transport
  substances throughout the body.