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Chapter1

Organization of the Human Body
or ...beginning the exploration of yourself

"The human body's organization, structures and inner workings are scientifically studied by the disciplines anatomy and physiology"

Objectives:

  •  Be able to define the terms anatomy and physiology
    - the sciences anatomy and physiology laid the foundation for a better under-
      standing of the complex structures and intricate functions of the fascinating
      human body;
    -
    Anatomy = the science of the structures and relationships among structures
      of the human body
        - historically, anatomy has its beginnings in the first studies of the Roman
           physician Galen
    -
    Physiology = the science of the body functions, that is, how the different
      parts of the body, e.g. organs, work
    - since body functions cannot be understood without a thorough under-
      standing of the structures which elicit the functions, anatomy and physiology
      are best studies together
     

  •  Know the different levels of organization of the human body
    - beginning with basic anatomy, the structures of the human body are
      organized on several
    hierarchical levels, which are (from largest to smallest):
        1.
    Organismal level
            - highest level of organization
            - all of the system of the
    body combine and work together to make a
              functional organisms = the human body
        2.
    System level
            - consists of related
    organs that have a common function, e.g.
               digesting food or assuring successful reproduction
            - sometimes an organ, e.g. the pancreas, is part of more than only one
              system
            - following
    11 principal systems are found operating within the human
              body:
                1.
    Integumentary System
                    - includes the skin, oil and seat glands, hair, finger- and toe-nails
                2.
    Skeletal System
                    - includes the bones, cartilage and the joints
                3.
    Muscular System
                    - includes: skeletal muscles and tendons
                4.
    Nervous System
                    - includes: brain, cerebrospinal fluid (CSF), spinal cord and
                      peripheral nerves
                5.
    Endocrine System
                    - includes: pineal gland, pituitary gland, thyroid gland, thymus,
                       pancreas, adrenal gland, ovaries/testis, fatty tissue,
                6.
    Cardiovascular System
                    - includes: 1 heart, blood, blood vessels (arteries, veins), capillaries
                7.
    Lymphatic and Immune System
                    - includes: lymphatic fluid and vessels, spleen, thymus, lymph nodes,
                       tonsils, immune cells, e.g. T- and B-lymphocytes, macrophages
                8.
    Respiratory System
                    - includes: larynx, pharynx, trachea (windpipe), bronchus, 2 lungs
                9.
    Reproductive System
                    - different in males and females:
                        Females: mammary gland, 2 uterine (fallopian) tubes, 2 ovaries,
                                         1 uterus, 1 vagina
                        Males: 2 ductus (vas) deferens, seminal vesicle, prostate gland,
                                     1 penis, 2 testis 
                10.
    Digestive System
                        - includes: mouth, salivary gland, esophagus, liver, gall bladder,
                           stomach, pancreas, small and large intestine, rectum, anus
                11.
    Urinary System
                        - includes: 2 kidneys, 2 ureters, urinary bladder, urethra,
        3.
    Organ level
            - have a recognizable shape and unique function(s)
            - composed of two or more different types of tissues
        4.
    Tissue level
            - groups of cells and their surrounding materials, e.g. ECM, that work
               together to perform a particular function;
            - 4 basic tissue types are classified within the human body:
                a. Epithelial tissue
                b. Connective tissue
                c. Muscle tissue
                d. Nervous tissue
            - a special "tissue" is blood
        5.
    Cellular level
            - cells are the smallest living units of life; they are the smallest structural
                and functional units of the human body;
            - contain specialized internal structures, called organelles
        6.
    Molecular level
            - are small structures that are made up from the joining of two or more
              chemical elements; the smallest molecule is hydrogen gas (H2)
            - large molecules are often referred to as "macro-molecules", e.g. DNA,
               glycogen in the liver, or ribosomes within cells;
            - important molecules of the human body are:
                proteins, DNA, RNA, glucose, ATP, 
        7.
    Chemical level
            - includes the atoms of the chemical elements important to life
               which are: C, O, H, N, Ca, Na, K, Mg, Fe,

Structural Organization of the Human Body

  •  Be able to define the important life processes operating within the human body
    - all living forms of life on planet Earth have characteristics that clearly set
       them apart from non-living (abiotic) matter; these characteristics are:
        1.
    Metabolism
            - metabolism = the sum of all chemical reactions/processes occuring
              within a body
            - metabolism is comprised of anabolism (= build-up metabolism)
                and catabolism (= degradative metabolism)
            - food molecules and other ingested molecules, e.g. drugs, are broken
               down into smaller pieces with the help of evolutionary highly
               conserved metabolic pathways, e.g. glycolysis, Krebs cycle
        2.
    Responsiveness
            - ability to detect and to respond to changes of its internal and/or external
              environment
            - involves the existence of receptors and/or nerve cells
        3.
    Movement
            - ability to move the whole body, individual organs, single cells, cell
               structures, e.g. cilia, or even organelles within cells;
        4.
    Growth
            - ability to increase the body size, or parts of the body due to
              regulated rounds of cell division (mitosis);
            - uncontrolled/unregulated growth leads to cancers/tumors within the
               body and eventual death;
        5.
    Differentiation
            - unspecialized (usually stem) cells become more specialized so-called
               differentiated cells with unique functions within the body
        6.
    Repair & Reproduction
         
     

  •   Be able to define the important physiological concept of homeostasis and to explains its importance for living organisms
    -
    Homeostasis is the ability of life forms to maintain relatively stable conditions
    - it assures that the body's internal environment and its critical parameters,
       such as temperature, pH, salinity, ion concentrations, remain steady despite
       changes inside and outside the body;
    - each of the body's systems contribute to some extent to hemostasis
    - the
    homeostatic mechanisms operating within the human body are mainly
      under the control of 2 major system:
            1. Nervous system
                - via nerves and propagated nerve impulses
            2. Endocrine system
                - with the help of produced hormones
    - homeostasis is maintained by means of many
    feedback systems or feedback
       loops;
        -
    3 basic components make up a feedback system:
            1. Receptor
            2. Control center
            3. Effector
    - feedback systems can produce either a negative or a positive feedback

Components of a typical feedback system

Homeostasis of the critical body parameter blood pressure
by a negative feedback system

  •   Be able to form out the connection between long-term disturbance of homeostasis and the development of disease
    - as long as the body is able to maintain homeostasis and to maintain its
      controlled conditions, e.g. blood pressure, glucose levels, pH, within certain
      narrow limits, the body stays in a healthy condition;
    - if one or more components of the body lose their ability to contribute to
      homeostasis the normal balance of the body's processes may become
      disturbed;
    - moderate imbalance of homeostasis can lead to a
    disorder or disease
        - Disorder = any disturbance of structure and/or function within the body
        - Disease = term for an illness characterized by a by a recognizable set
                              of signs and symptoms
                            -
    signs (in clinical terms) are objective changes that a clinician
                               can observe and measure, e.g. bleeding, swelling, vomiting,
                                diarrhea, fever, or a rash
                            - symptoms are subjective changes in body functions that are
                               NOT apparent to an observer, e.g. headache or nausea
     

  •  Be able to describe some of the effects of aging
    - aging is a normal, irreversible biological process which is characterized by
      by a progressive decline in the body's ability to maintain and restore homeo-
      stasis
    - aging produces a series of observable changes in structure and function of
      several body parts, examples are:
            weakened bones and loss of bone mass, wrinkled skin, grey hair,
             decreased muscle mass, diminished reflexes, increased incidence of
             heart disease, increased susceptibility to infections and cancer,
    - it increases the vulnerability to stress, infections and disease
     

  •  Be able to identify the major regions of the human body and to relate the common names to the corresponding correct anatomical terms
    - the language of anatomy and physiology is and has to be very precise in
      order to avoid confusion and mistakes in professional environments, such
      as hospitals and health-related fields; to describe body parts and its exact
      locations, anatomists use
    anatomical terms;
    - in the study of anatomy, descriptions of any part of the human body assume
      that the body is in the correct
    "anatomical position";
        - the person stands erect facing the observer, with the head level, and the
           eyes facing forward; the feet are flat on the floor and directed forward,
           and the arms are at the sides with the palms turned forward;
           (see
    Figure below)

The anatomical position

  •   Be able to use directional anatomical terms to correctly describe different parts
    of the human body
    - anatomists use specific
    directional terms to locate various body structures and
      to correctly describe the position of one body part relative to another;
    - important directional terms and their meaning are:
        1.
    Superior                towards the head/upper part
        2.
    Inferior                  away from the head/lower part of a structure
        3.
    Anterior                 nearer to or at the front of the body
        4.
    Posterior                nearer to or at the back of the body
        5.
    Medial                    nearer to the midline of the body
        6.
    Lateral                    farther from the midline
        7.
    Proximal                nearer to the attachment of a limb to the trunk;
                                             nearer to the point of origin
        8.
    Distal                      farther from the attachment of a limb to the trunk;
                                             farther from the point of origin
        9.
    Superficial              toward or on the surface of the body
        10.
    Deep                      away from the body's surface

Directional terms and the human body

  •  Be familiar with the four major planes of the human body
    - modern analysis and diagnosis of the human body, e.g. with the help of
      tomography and MRI, requires a good understanding of the terminology
      connected to the different
    planes of the human body;
    - planes are imaginary flat surfaces that pass through the body parts
    - four major body planes are defined which are:
            1.
    Sagittal plane
                1a.
    Midsagittal plane
                        - vertical plane through the midline
                1b.
    Parasagittal plane
                        - vertical plane left or right of the midline
            2.
    Frontal (or coronal) plane
                - divides body into anterior and posterior portions
            3.
    Transverse (or horizontal) plane
                - divides body (or organs) into superior and inferior portions
            4.
    Oblique plane
                - plane that passes through the body (or an organ) at an angle
                   between the transverse plane and a sagittal (or frontal) plan

Planes of the human body

  •  Be able to describe the principal body cavities of the human body and the organs
    they contain

    -
    body cavities are spaces within the human body that contain, protect, separate and support
      internal organs
    - the two principal body cavities are the:
        1.
    Dorsal body cavity
            - includes the
    cranial cavity and the vertebral (spinal) canal
            and
        2.
    Ventral body cavity
            - includes the thoracic and abdominopelvic cavities

Body cavities of the human body

  •   Be able to locate the nine regions of the abdominopelvic cavity and to assign
     important organs to each of the sections

    - the "tick-tack-toe"-like grid partitioning of the abdominopelvic cavity into
       nine smaller compartments is used for anatomical studies and allows precise
       naming of locations of certain symptoms
    - the nine-region division is more widely used for general anatomical studies

The nine regions of the abdominopelvic cavity
of the human body


  •  Be able to name and locate the quadrants of the abdominopelvic cavity of the human body.
    - this type of dividing the abdominopelvic cavity into virtual four quadrants by drawing one
       horizontal and one vertical line passing through the umbilicus (or navel) of the human body is
       shown below.
    - quadrants are more widely used by clinicians to describe the site of an abdominopelvic pain,
       mass, or other abnormality

                                               
    The quadrants of the human abdominopelvic cavity

  •  


       Medicine & Pathology:

    •  Make yourself familiar with the meaning of the following medical terminology & conditions:

                                                                  Key term

      Epidemiology                                  The science dealing with why, when, and where diseases
                                                                  occur and how they are transmitted within a defined and studied
                                                                  population, an ethnic group, country, community

      Geriatrics                                           The science that deals with the medical problems and care of elderly
                                                                   persons

      Pathology                                          The science that deals with the nature, causes, and development of
                                                                   abnormal conditions and the structural and functional changes that
                                                                   come with the diseased status;

      Pharmacology                                   The science that deals with the effects and use of drugs in the treatment
                                                                   of disease

      Toxicology                                         The science dealing with the effects of - natural or environmental -
                                                                    toxins and poisons on the human body and the diseases caused by
                                                                    them;