Tissues, Glands and Membranes

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Tissues, Glands and Membranes

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• A tissue is a group of cells that have a
  similar structure and function
• The microscopic study of tissues is called
  histology

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Four Types of Tissue

• Epithelial
• Connective
• Muscle
• Nervous

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Epithelial Tissue
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• Epitihelial Covering Lining
• Covers internal and external surfaces
  throughout the body
• Three parts free surface
• basement membrane
• very little extracellular
  space

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• Functions of the epithelial cell
• Protects the underlying structures- for example
  the skin
• Acts as a barrier to certain substance- for
  example water, toxic molecules, and
  microorganisms
• Also allows the passage of certain substances
  for example oxygen and carbon dioxide
• Secretes substance for example secretions from
  sweat glands
• Absorbs substances for example vitamins,
  minerals

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• Classified according to the number of layers and
  the cell shape
• of layers Cell shape
• Simple (one layer) Squamous
• 
  Cuboidal
• 
  Columnar
• Pseudo stratified Columnar
• Stratified Squamous
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  Keratinized
• Non
  Keratinized
• Transitional Roughly cuboidal to
  columnar
• when not
  stretched,squamous
• when
  stretched

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• The structure relates to the function
• Simple epithelium- found in movement epithelium
• - gasses across wall of alveoli
• - filtration of fluid across kidneys
• - secretion of glands
• - nutrient absorption

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• Sratified epithelium
• well adapted for its protective function
• as outer layers are damaged , they are replaced
  by deeper cell layers
• Found where abrasions may occur, such as skin,
  anal canal and vaginal canal

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• Differences also reflected in the cell shape
• Flat and thin cells for diffusion in lungs and
  filtration in kidneys
• Cuboidal or columnar cells are cells with major
  functions of secretion or absorption. They are
  larger because they contain more organelles for
  all the functions they must perform e.g. columnar
  cells of the stomach lining have secretory
  vesicles that secrete mucus.

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Free Surface of the cell
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Cell Connections
Cell Connections Tight Junctions
Desmosoes Hemidesmosomes Gap junctions
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Glands

• Glands- A gland is a multicellular structure
  that secretes substances on to a surface, into a
  cavity or into the blood
• Most are made of epithelial cells

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Types of Glands

• Exocrine- glands that have ducts
• - simple- no branches
• -compound- branches
• ends- 1-tubular
• straight tubular
• coiled tubular
• 2- acinar/ alvoelar or
  saclike
• 3- both tubuloacinar

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Types of Exocrine Glands
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Endocrine Glands

• Endocrine-have no ducts and empty their
  secretions directly into the blood
• Secretions are called hormones and these hormones
  are carried to other parts of the body by the
  blood

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Connective Tissue
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Connective Tissue

• Connective Tissue structure large amounts of
  extracellular materials that separate cells from
  one another
• This extracellular matrix is divided into three
  parts
• -protein fibers
• - ground substance consisting of non
  fibrous protein and other molecules
• - fluid

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Connective Tissue Matrix
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Protein Fibers

• - Collagen Fibers- resemble
  microscopic ropes, flexible but resist bending
• - Reticular Fibers- very fine short
  collagen fibers that branch to form the
  supporting network
• - Elastic Fibers- structure similar to
  coiled metal bed springs
• but after being stretched , elastic fibers
  recoil to their original shape

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Connective Tissue Matrix
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Ground Substance

• Ground Substance is the shapeless background
  against which cells and collagen fibers are seen
  in the light microscope
• Made up of highly structured molecules
• Consists of Proteoglycans (proteins and
  carbohydrates that trap water)

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Connective Tissue Matrix
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Cells of the matrix
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How Do We Name Connective Tissue ?

• According to Their Functions
• examples
• Blast- produces the matrix
• Cyte maintains the matrix
• Clast-break down the matrix for
• remodeling
• Macrophage
• Mast Cell

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Functions of the Connective Tissue

• Encloses and Separates
• Connecting tissue to one another
• Supporting and Moving
• Storing
• Cushioning and insulating
• Transporting
• Protecting

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Classification of Connective Tissue

• Loose (areolar)
• Adipose
• Dense Connective Tissue
• - Dense collagenous connective
• A) Collagen arranged in same
  direction
• B) Collagen arranged in many
  directions
• Dense elastic connective tissue
• A)Elastic arranged in many directions
• b) Elastic fibers arranged in same
  direction
• Cartilage
• Hyaline
• FIbrocartilage
• Elastic Cartilage
• Bone
• Blood

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Loose Areolar Tissue -mostly collagen, few
elastic and widely separated from each
otherProduced by the fibroblastThis is the
tissue that fills in the spaces
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Loose Connective TISSUE
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Adipose Tissue

• Has very little collagen and elastic fibers
• Large cells filled with lipids
• Pads of protection and thermal insulation

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Dense Connective Tissue

• Densely packed fibers that produced by the
  fibroblast
• Dense Collagenous- mostly collagen
• tendons, ligaments, capsules around
  organs
• same direction in tendons,
  different in organs
• Dense Elastic Tissue- abundant elastic fibers
  among collagen fibers
• vocal cords, walls of large
  arteries

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Dense Elastic
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Cartilage

• Composed of cartilage cells or
  Chondrocytes
• Located in the matrix along with collagen
• Amongst the extracellular matrix
• It gives the matrix resilience
• Hyaline
• Fibro
• Elastic

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Hyaline Cartilage

• The most abundant type of cartilage
• Ends of bones where they come together to form
  joints. It is the smooth and resilient
• Surfaces that withstand repeated compression
• Costal , respiratory, and nasal cartilges

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Fibrocartilage

• Has more fibrous tissue than does hyaline
  cartilage
• , bundles of collagen
• Resists pulling or tearing
• Found in the disks between vertebrae and in some
  joints

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Elastic Cartilage

• Has elastic fibers, collagen proteoglycans
• Coiled fibers amongst bundles of collagen fibers
• Can recoil to its original shape when bent
• External ear, epiglottis, auditory tube

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Bone

• Is hard connective tissue that consists of cells
  and a mineralized matrix
• Osteoblasts secrete the matrix called lamellae
• osteocytes are located in lacune
• The Osteon ( Haversion system) consist of
  central canal with blood vessels, osteocytes and
  lamellae

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Haversion System/Osteon
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Blood

• Here the matrix is a liquid which enables the
  blood to move through the vessels to carry
  nutrients and other materials

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Muscle Tissue

• Main Characteristic is its ability to contract ,
  making movement possible
• Contractile proteins in the muscle cells
  themselves, called actin and myosin
• Muscle cells are called muscle fibers because
  they resemble tiny threads

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Three Types of Muscle Tissue

• Skeletal Muscle
• Cardiac Muscle
• Smooth Muscle

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Skeletal Muscle

• Normally thought of as muscle
• Meat of animals, 40 of persons body weight
• Attaches to the skeletal system and enables body
  movement
• Long and cylindrical cells with several nuclei
  per cell Some cells are the entire length of the
  muscle
• Striated,
• Vountary

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Smooth Muscle

• Forms the hollow walls of the organs and is also
  in the skin and eyes
• Movement of food and emptying of the Urinary
  Bladder
• Involuntary
• Tapered at each end , have a single nucleus and
  are not striated

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Cardiac Muscle

• Muscle of the heart and is responsible for
• Involuntary control
• Cylinder in shape and shorter than skeletal
• Striated and one nucleus
• Connected by intercalated disks

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Classification of Muscles

• Skeletal Smooth Cardiac
• Voluntary involuntary involuntary
• Striated not striated striated
• gt1nuclei 1 nuclei 1 nuclei

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Nervous Tissues

• Forms the brain, spinal cord and nerves
• Coordinates and controls many body activities
• Conscious and unconscious
• Awareness, emotion, reasoning
• Communicate through action potentials
• Cell neuron or nerve cell responsible for
  conduction of action potentials
• Neuron cell body , dendrites and axons
• Neuroglia surrounding support cells

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Neurons and Glial cells
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Membranes

• Serous Membranes
• simple squamous epithelium resting on
  delicate layers of loose connective tissue
• cavities and cover the organs inside
  these cavities
• secretes serous fluid which lines the
  cavitites
• prevents trauma and damage

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Membranes

• Pleural- lungs - Pleuritis
• Pericardium- heart - Pericarditis
• Peritoneal other - Peritonitis

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Other Membranes

• Cutaneous
• Synovial
• Periosteal