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2012-01-21 13:37:06
human physiology

human organ system and physiology
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  1. Tissue

    –Group of cells of a common embryonic origin

    –Develops from three primary germ cells during embryonic development

    –Perform specialized function within the body

    –Histogenesis – formation of tissue

    –Histology- study of the microscopic anatomy of cells and tissues
  2. Four Major Categories of Tissue:

    •Connective tissue

    •Muscle tissue

    •Nervous tissue
  3. Cell Junctions
    •Cells are joined together into functional units

    •Cell Junctions are contact points between the plasma membranes of the tissue cells

    –Tight Junctions

    •Form a leak-proof seal

    •Prevent the passage of molecules and ions through the space between cells

    •Example: Found between epithelial cells of the digestive tract
  4. Adherens Junctions
    •Resemble a riveted joint

    •Provide strong mechanical attachment between adjacent cells

    • •Cadherins- transmembrane
    • proteins

    •Example: Cardiac muscle

    –Hold cells tightly together as the heart expands and contracts
  5. Gap Junctions
    •Intercellular channels (1.5-2 nm in diameter)


    •Allow free passage of ions between the cells

    •Examples: Cardiac cells, smooth muscle cells of the uterus
  6. Desmosomes and Hemidesmosomes

    •Hold two cells tightly together

    •Attached to intermediate filaments of keratin in the cytoplasm

    •Example: Skin


    •Similar to desmosomes

    •Attach epithelial cells to basal lamina (basement membrane)
  7. Epithelial Tissue
    • •Epithelial cell is composed of apical, lateral and basal
    • surfaces

    –Apical Surface

    •Faces body surfaces, body cavities, or external environment

    • •Microvilli: Small intestine -­ surface
    • area for absorption

    •Cilia: Respiratory tubes; move mucus into one direction

    Flagella: Spermatoza
  8. Lateral surface and Basal
    –Lateral Surface

    •Face the adjacent cells on either site


    •Opposite to the apical surface

    •Deepest layer of cells, adhere to extracellular materials

    •Composed of two layers:

    –Basal lamina

    »Secreted by epithelial cells

    »Contains collagen and glycoproteins

    –Reticular lamina

    »Contains fibrous proteins
  9. Epithelium tissue composition and function.
    •Epithelial tissues

    –Is composed of cells arranged in continuous layer

    •Single or multiple layers

    –Possess nerve supply, but no blood supply

    •Epithelium serves three major functions:

    –Covers the outer and inner surfaces of the body

    –Composes the glands

  10. Characteristics of epithelium cells and arrangement.
    •Epithelial cells classified into two characteristics:

    –Arrangement of cells into layers

    •One layer = simple epithelial tissue

    –Usually functions as a diffusion and absorption membrane

    –Example: Respiratory membranes of the lungs

    •Multiple layers = stratified epithelial tissue

    –Designed for protection

    –Example: outer layer of skin, ducts of salivary glands

    –Shape of the cells




  11. Simple Squamous Epithelium
    –A single layer of flat cells

    •Centrally located nucleus

    –Present where process of filtration, diffusion or secretion occur

    –Eg. Blood vessels, lymphatic vessels, air sacs of lungs
  12. Simple Cuboidal Epithelium
    –A single layer of cube-shaped cells

    •Centrally located nucleus

    –Present where process of secretion and absorption occur

    –Eg. Lining of kidneys, secreting portion of thyroid gland
  13. Simple Columnar Epithelium
    –Cells appear taller than they are wide

    –Nuclei near the base of cells


    •Line the GI tract (stomach-anus), and gallbladder

    •Function in secretion and absorption

    •Goblet cells

    –Modified columnar epithelium that secrete mucus


    •Line some portions of upper respiratory tract, fallopian tubes

    •Function in moving mucus and other substances
  14. Pseudostratified Columnar Epithelium
    –Not a true stratified epithelium

    • –All cells are attached to basement membrane,
    • but not all reach apical surface

    –Lines most of the upper respiratory tract

    –Secretion of mucus
  15. Stratified Squamous Epithelium
    –Varying shape of cells

    • –Apical layer more akin to simple squamous where
    • basal layers vary in shape from cuboidal to
    • columnar

    –Primary Function


    • –Located on surface of skin, lining mouth, esophagus and
    • vagina
  16. Transitional Epithelium
    • –Lines urinary bladder and parts of ureters and
    • urethra
  17. Epithelial Tissue Forms Glands
    •Exocrine Glands

    –Secrete its products into ducts

    –Salivary glands and sweat glands

    •Endocrine Glands

    –Have no glands

    –Secrete its products directly into the extracellular fluid surrounding the gland

    –Adrenal, thyroid and pituitary glands

    –Example: Hormones
  18. Epithelial Membranes
    •Mucous Membranes

    –Lines body cavities

    –Opens directly into the exterior

    •Serous Membranes

    –Lines body cavities

    –Does not open directly to the exterior

    •Perietal layer

    •Visceral layer

    •Cutaneous Membranes


    –Covers the surface of the body

    •Synovial Membranes
  19. Connective Tissue
    •One of the most abundant tissues in the body

    • •Composed of extracellular matrix (protein fibers and ground substance) and
    • cells

    •Highly vascular (with the exception of cartilage and tendons)

    •Connective tissue extracellular matrix

    –Ground substance

    •May be fluid, semi-fluid, gelatinous, or calcified

    •Polysaccharides or glycosaminoglycans (GAGs)
  20. Fibers
    •Strengthen and support connective tissue

    •Collagen fibers

    •Elastic fibers

    •Reticular fibers
  21. Loose and dense connective tissues
    •Loose and dense connective tissues differ in the ratio of cells to extracellular fibers.
  22. Areolar Connective Tissue
    –Most widely distributed connective tissue

    –Include fibroblast, macrophages, plasma cells and adipocytes
  23. Reticular Connective Tissue
    –Composed of reticular fibers and cells

    –Forms stroma of the spleen, liver and lymph nodes
  24. Adipose Tissue (fat)
    •Found below skin and throughout the body


    –Long term energy store


    –Protection of tissues from damage

    –Endocrine gland

    •Possess non-living extracellular matrix

    •Cellulite - “bumps on the skin”

    • –Indicate where the adipose matrix is connected to the
    • skin

    –Normal function of fat deposition and storage
  25. Dense Connective Tissue
    •Contains more fibers, but fewer cells

    •Dense regular connective tissue

    –Collagen fibers arranged in a parallel pattern

    –Forms tendons and most ligaments

    •Dense irregular connective tissue

    –Irregular arrangement of collagen fibers

    –Found in dermis of the skin, heart valves

    •Elastic connective tissue

    –Composed mostly of elastic fibers

    –Posses the ability to recoil

    –Found in lungs
  26. Cartilage
    •Cartilage is a dense connective tissue composed from collagenous fibers and/or elastic fibers and chondrocytes, all embedded in matrix –chondroitin sulfate

    –Tough, semi-transparent, elastic and flexible

    –No blood vessels- nutrients diffuse through the matrix

    –No nerves

    –Often found in the association with bone

    –Osteoarthritis-a serious diseaseof joints, targeting the cartilage found within them.
  27. Cartillage functions
    –Reduces friction at joints (hyaline cartilage)

    • –Supports the structures (hyaline cartilage in the
    • windpipes (trachea and bronchi) assist in keeping those
    • tubes open

    –Shock absorber (fibrocartilage between adjacent vertebrates)
  28. Elastic Cartilage
    –Composed of elastin (yellow) and collagen

    –Makes up the springy part of the outer ear

    • –Forms the epiglottis (the flap of tissue that prevents food from entering the
    • airways)
  29. Fibrocartilage
    –Large amounts of collagen

    –Provides strength and rigidity

    • –Found in bones of the spinal column (intervertebral discs),
    • hips and pelvis
  30. Hyaline cartilage
    –Contains fine collagen fibers

    –Forms the skeleton in the embryo

    –Remains as a thin layer on the ends of bones which form joints

    –Forms the end of the nose, and the stiff rings around the windpipe

    –Forms the ends of the ribs and supports the larynx
  31. Muscular Tissue
    •Consists of elongated cells called muscle fibers that use ATP to create a force

    • •These tissues produce/resist movement, maintain posture,
    • generate heat and provide protection

    •Three types of muscle

    –Cardiac Muscle

    –Smooth Muscle

    –Skeletal Muscle
  32. Cardiac Muscles
    –Heart muscles

    •Walls of the heart

    –Cardiac muscle has short, branched, striated cells

    •One nucleus

    –Involuntary (contractions are NOT consciously controlled)

    –Pumps blood through the body
  33. Smooth muscle
    –Lines hollow organs such as the blood vessels and the digestive tract

    –Smooth muscle cells are short and cylindrical; they have only one nucleus

    •When arranged in circles controls diameter of tube

    –Smooth muscle cells are NOT under voluntary control.
  34. Skeletal muscle
    –Attached to the skeletal system through tendon insertions

    –Striated appearance (dark and light sections)

    –Made up of individuals fibres of approximately 50um in diameter

    –Smallest functional unit of skeletal muscle is the sacromere

    –Motor Neuron

    •The alpha motor neuron and the muscle fibres that it innervates

    •Many motor units in a single muscle
  35. Supporting Connective Tissue - Bone
    –Specialized connective tissue that together with cartilage forms skeleton

    –Composed from calcium phosphate and other organic salts

    –Three types of cells

    •Osteoblast- bone forming cells

    •Osteoclast- bone resorbing cells

    •Osteocyte- cells which maintain the fully formed bone

    –Two types of bone

    •Spongy bone (cancellous, trabecular)

    •Compact bone (lamellar)


    –Muscle attachment site

    –Protects viscera

    –Marrow site

    –Ca2+ depot
  36. Blood and Lymph

    –Transport of the respiratory gases, nutrients and waste products

    –Composed of extracellular matrix (blood plasma) and formed elements (red blood cells, white blood cells and platelets)


    –It is derived from interstitial fluid that bathes the cells

    –Contained within lymphatic vessels
  37. Nervous tissue
    •Two types of cells:



    •Responsible for the transmitting information

    –Glia Cells

    •Supporting cells of the nervous system


    •Provide physical support, remove debris and provide electrical insulation
  38. Neuron Structure
    •Cell body

    –Control center of the cell


    –Processes that branch of the cell body

    –Receive input from other neurons


    –Transmit nerve impulses away from the cell body toward another cell
  39. Types of Neurons
    –Sensory neurons

    •Carry information from sensory receptors to the CNS

    •Afferent neurons

    –Motor neurons

    •Usually have along axons and short dendrites

    •Transmit the messages from the CNS to the muscles/glands

    •Efferent neurons


    •Found only in the CNS

    •Connect neurons