THE HUMAN BODY AN ORIENTATION

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THE HUMAN BODYAN ORIENTATION

• An Overview of Anatomy and Physiology

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Anatomy

• Study of the structure of body parts and their
  relationships to each other
• Anatomy Greek meaning to cut apart

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Physiology

• Study of the function of body parts
• How all the body parts work and carry out their
  life-sustaining activities

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Topics of Anatomy

• Gross (macroscopic) anatomy the study of
  structures large enough to be seen with the naked
  eye
• Regional anatomy all the body structures
  (muscles, bones, blood vessels, nerves, etc.) in
  a given body region , such as the abdomen or leg,
  are examined at the same time
• Systemic anatomy body is studied system by
  system
• Example when studying the cardiovascular system,
  you would examine the heart and the blood vessels
  of the entire body
• Surface anatomy internal body structures as they
  relate to the overlying skin
• Used when identifying the bulging muscles beneath
  a bodybuilders skin, and clinicians use it to
  locate appropriate blood vessels in which to feel
  pulses and draw blood

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Topics of Anatomy

• Microscopic anatomy the study of structures that
  are too small to be seen with the naked eye
• Cytology study of individual cells
• Histology study of tissues
• Developmental anatomy the study of the change in
  body structures over the course of a lifetime
• Embryology concerns developmental changes that
  occur before birth

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Topics of Anatomy

• Specialized Branches of Anatomy
• Pathological anatomy study of structural changes
  associated with disease
• Radiographic anatomy study of internal
  structures using specialized visualization
  techniques (X-rays or special scanning devices)
• Molecular biology study of biological molecules

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Topics of Physiology

• Considers the function of specific organ systems
• Examples
• Renal physiology concerns kidney function and
  urine production
• Neurophysiology explains the workings of the
  nervous system
• Cardiovascular physiology examines the operation
  of the heart and blood vessels
• While anatomy provides us with a static image of
  the bodys architecture, physiology reveals the
  bodys dynamic nature

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Topics of Physiology

• Focuses on cellular and molecular events
• Individual cells and the chemical reactions that
  go on within them
• Principles of physics which helps to explain
  electrical currents, blood pressure, and the way
  muscles use bones to cause body movements

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Complementarity of Structure and Function

• Function is dependent on structure, and the form
  of a structure relates to its function
• What a structure can do depends on its specific
  form
• Examples
• Bones can support body organs because they
  contain hard mineral deposits
• Blood flows in one direction through the heart
  because the heart has valves that prevent
  backflow
• Lungs can serve as a site for gas exchange
  because the walls of their air sacs are extremely
  thin

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Levels of Structural Organization

• (1)Chemical level is the simplest level of
  organization
• Atoms, tiny building blocks of matter, combine to
  form molecules such as water and proteins
• Molecules combine in specific ways to form
  organelles, which are the basic unit of living
  cells
• Cells are the smallest units of living things
• All cells have some common functions, but
  individual cells vary widely in size and shape,
  reflecting their unique functions in the body

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Levels of Structural Organization

• (2)Cellular level smallest unit of life, and
  varies widely in size and shape according to the
  cells function
• (3)Tissue level groups of similar cells having
  a common function
• Four basic tissue types each tissue type has a
  characteristic role in the body
• Epithelium covers the body surface and lines its
  cavities
• Muscle provides movement
• Connective supports and protects body organs
• Nervous provides a means of rapid internal
  communication by transmitting electrical impulses

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Levels of Structural Organization

• (4)Organ level made up of discrete structures
  that are composed of a least two groups of
  tissues that work together to perform a specific
  function in the body
• Stomach epithelium lining, muscles, blood
  vessels, connective tissues, nerve fibers, etc.
• (5)Organ system level a group of organs that
  work closely together to accomplish a specific
  purpose
• Respiratory and circulatory system, digestive and
  circulatory systems
• (6)Organismal level the total of all structures
  working together to promote life
• The living human being

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Levels of Structural Organization
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Maintaining Life Necessary Life Functions

• (a) Maintaining Boundaries allows an organism
  to maintain separate internal and external
  environments, or separate internal chemical
  environments
• Integumantary System or Skin
• (b) Movement allows the organism to travel
  through the environment, and allows transport of
  molecules within the organism
• Skeletal, Circulatory, Muscular Systems
• (c) Responsiveness or irritability, is the
  ability to detect changes in the internal or
  external environment and respond to them
• Muscular System

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ORGAN SYSTEMS
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Maintaining Life Necessary Life Functions

• (d) Nervous System
• Responsiveness to external and internal
  environments by activating muscles and glands
• (e) Endocrine System
• Regulating body functions such as growth,
  reproduction, and nutrition
• (f) Cardiovascular System
• Transportation of nutrients, waste, gases, and
  hormones throughout the body

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ORGAN SYSTEMS
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Maintaining Life Necessary Life Functions

• (g) Lymphatic System/Immunity
• Body defenses
• (h) Respiratory System
• External and internal gas exchanges
• (i) Digestive System
• Breakdown and absorption of nutrients

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ORGAN SYSTEMS
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Maintaining Life Necessary Life Functions

• (j) Urinary System
• Absorption of waste from the blood and
  elimination
• (k) Male Reproductive System
• Production of sperm
• (l) Female reproductive System
• Production of eggs

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ORGAN SYSTEMS
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Maintaining Life Necessary Life Functions

• Digestion is the process of breaking down food
  into molecules that are usable by the body
• Metabolism includes all chemical reactions that
  occur in the body
• Excretion is the process of removing wastes
• Reproduction is the process of producing more
  cells or organisms
• Growth is an increase in size in body parts or
  the whole organism

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Examples of selected interrelationships among
body organ systems

• Integumentary system protects the body as a whole
  from the external environment
• Digestive and respiratory systems, in contact
  with the external environment, take in nutrients
  and oxygen, respectively, which are then
  distributed by the blood to all body cells
• Elimination of metabolic wastes is accomplished
  by the urinary and respiratory systems

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ORGAN SYSTEMS
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Survival Needs

• The ultimate goal of all body systems is to
  maintain life
• Life is extraordinarily fragile and requires that
  several factors be present
• These factors are called survival needs and
  include
• Nutrients consumed chemical substances that are
  used for energy and cell building
• Oxygen required by the chemical reactions that
  release energy from foods
• Water most abundant chemical substance in the
  body, provides an environment for chemical
  reactions and a fluid for secretions and
  excretions
• Normal body temperature required for the
  chemical reactions of the body to occur at the
  proper rate
• Atmospheric pressure must be within an
  appropriate range so that proper gas exchange
  occurs in the lungs

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Homeostasis

• The ability of the body to maintain a relatively
  constant internal environment, regardless of
  environmental changes
• Body temperature
• Blood pH

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Homeostatic Control Mechanisms

• Communication within the body is essential for
  homeostasis
• Accomplished chiefly by the nervous and endocrine
  systems
• All homeostatic control mechanisms have at least
  three interdependent components
• 1. Receptor type of sensor that monitors the
  environment and responds to changes, called
  stimuli, by sending information (input) to the
  second component (control center)

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Homeostatic Control Mechanisms

• 2. Control Center
• Information flows from the receptor to the
  control center along the afferent pathway
• Structure that determines the set point (level or
  range at which a variable is to be maintained)
  for a variable, analyzes input, and coordinates
  an appropriate response
• Variable the regulated factor or event

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Homeostatic Control Mechanisms

• 3. Effector
• Provides the means for the control centers
  response (output) to the stimulus
• Structure that carries out the response directed
  by the control center
• Information flows from the control center to the
  effector along the efferent pathway
• The results of the response then feed back to
  influence the stimulus, either depressing it
  (negative feedback) so that the whole control
  mechanism is shut off or enhancing it (positive
  feedback) so that the reaction continues at an
  even faster rate

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CONTROL SYSTEM
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Negative Feedback Mechanisms

• Most homeostatic control mechanisms are negative
  feedback mechanisms
• In these systems, the output shuts off the
  original stimulus or reduces its intensity
• These mechanism cause the variable to change in a
  direction opposite to that of the initial change,
  returning it to its ideal value
• Both the nervous system and the endocrine system
  are important to the maintenance of homeostasis
• The goal of negative feedback mechanisms is to
  prevent sudden, severe changes in the body

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Negative Feedback Mechanisms

• Home heating system connected to a
  temperature-sensing thermostat
• Thermostat houses BOTH the receptor and the
  control center
• If thermostat is set at 20oC (68oF), the heating
  system (effector) is triggered ON when the house
  temperature drops below that setting
• As the furnace produces heat and warms the air,
  the temperature rises, and when it reaches 20oC
  or slightly higher, the thermostat triggers the
  furnace OFF
• This process results in a cycling of furnace-ON
  and furnace-OFF so that the temperature in the
  house stays very near the desired temperature of
  20oC
• Your body thermostat, located in a part of your
  brain called the hypothalamus, operates in a
  similar fashion

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Negative Feedback Mechanisms

• To carry out normal metabolism, body cells need a
  continuous supply of glucose, their major fuel
  for producing cellular energy, or ATP
• Blood sugar levels are normally maintained around
  90 milligrams (mg) of glucose per 100 millimeters
  (ml) of blood
• Rising glucose levels stimulate the
  insulin-producing cells of the pancreas, which
  respond by secreting insulin into the blood
• Insulin accelerates the uptake of glucose by most
  body cells
• It also encourages storage of excess glucose as
  glycogen in the liver and muscles
• Consequently, blood sugar levels ebb back toward
  the normal set point, and the stimulus for
  insulin release diminishes

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NEGATIVE FEEDBACK
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Negative Feedback Mechanisms

• Glucagon, another pancreatic hormone, has the
  opposite effect of insulin
• Its release is triggered as blood sugar levels
  decline below the set point
• Glucagon secretion is stimulated
• Glucagon targets the liver, causing it to release
  its glucose reserves from glycogen into the blood
• Consequently, blood sugar levels increase back
  into the homeostatic range
• There are hundreds of Negative Feedback
  Mechanisms (regulation of heart rate, blood
  pressure, rate and depth of breathing, and blood
  levels of oxygen, carbon dioxide, and minerals)

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NEGATIVE FEEDBACK
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Positive Feedback Mechanisms

• Result or response enhances the original stimulus
  so that the activity (output) is accelerated
• A positive feedback mechanism causes the variable
  to change in the same direction as the original
  change, resulting in a greater deviation from the
  set point
• Positive feedback mechanisms typically activate
  events that are self-perpetuating
• Once initiated, have an amplifying effect
• Most positive feedback mechanisms are not related
  to the maintenance of homeostasis
• Homeostatic imbalance often results in disease

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Positive Feedback Mechanisms

• Examples
• Enhancement of labor contractions during birth
• Oxytocin, a hypothalamic hormone, intensifies
  labor contractions during the birth of a baby
• Causes the contractions to become more frequent
  and more powerful until the baby is finally born,
  an event that ends the stimulus for oxytocin
  release and shuts off the positive feedback
  mechanism

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Positive Feedback Mechanisms

• Examples
• Blood clotting
• Blood clotting is a normal response to a break in
  the lining of a blood vessel
• 1. Once vessel damaged has occurred
• 2. Blood elements called platelets immediately
  begin to cling to the injured site
• 3. Platelets release chemical that attract more
  platelets
• 4. This rapidly growing pileup of platelets
  initiates the sequence of events that finally
  forms a clot

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POSITIVE FEEDBACK
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Homeostatic Imbalance

• Homeostasis is so important that most disease is
  regarded as a result of its disturbance, a
  condition called Homeostatic Imbalance
• Causes
• As we age, our bodys control systems become less
  efficient
• Negative feedback mechanisms become overwhelmed
  and destructive positive feedback mechanisms take
  over

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Language of Anatomy Anatomical Position and
Directional Terms

• To describe body parts and position accurately,
  we need an initial reference point and must
  indicate direction
• The anatomical reference point is a standard body
  position called the Anatomical Position
• Anatomical Position position in which the body
  is
• Erect with feet only slightly apart
• Palms face forward
• Thumbs point away from the body

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REGION TERMS
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REGION TERMS
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Language of Anatomy Anatomical Position and
Directional Terms

• In anatomical position, right and left refer to
  the right and left sides of the person viewedNOT
  those of the observer
• In anatomy, anatomical position is always
  assumed, regardless of the actual position of the
  body

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Language of Anatomy Anatomical Position and
Directional Terms

• Directional terms are used to explain exactly
  where one body part is in relation to another
• Example
• The ears are located on each side of the head to
  the right and left of the nose
• Using anatomical terminology, this condenses to,
• The ears are lateral to the nose
• Saves words and is less ambiguous
• Anatomical meanings are VERY PRECISE

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Orientation and Directional Terms
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Orientation and Directional Terms
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Orientation and Directional Terms
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Regional Terms

• There are two fundamental divisions of the body
• Axial region
• Makes up the main axis of our body
• Includes the head, neck, and trunk
• Appendicular region
• Consists of the appendages, or limbs
• Attached to the bodys axis
• Consists of the upper and lower limbs
• Regional terms are used to designate specific
  areas within the major body divisions
• The common term for each of these body regions is
  provided (in parentheses)

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REGION TERMS
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REGION TERMS
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Body Planes and Sections

• For anatomical studies, the body is often
  sectioned (cut) along a flat surface called a
  plane
• Body planes are flat surfaces that lie at right
  angles to each other
• Sagittal plane a vertical plane that separates
  the body into right and left parts
• Median, or midsagittal plane lies exactly along
  the bodys midline
• Parasagittal plane (paranear) lies offset from
  the midline
• Frontal plane a vertical plane that separates
  the body into anterior and posterior parts
• Transverse, or horizontal, plane a plane that
  runs horizontally from right to left, and divides
  the body into superior and inferior parts

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BODY PLANES
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Body Planes and Sections

• Transverse, or horizontal, plane a plane that
  runs horizontally from right to left, and divides
  the body into superior and inferior parts
• Many different transverse planes exist, at every
  possible level from head to foot
• Transverse section, or cross section, is a cut
  made along the transverse plane
• Oblique sections are cuts made at angles between
  the horizontal and vertical planes
• The ability to interpret sections made through
  the body, especially transverse sections, is
  important in the clinical sciences
• New medical imaging devices produce sectional
  images rather than three-dimensional images

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BODY PLANES
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Body Cavities and Membranes

• Within the axial portion of the body are two
  large cavities called the dorsal and ventral body
  cavities
• Body cavities are spaces within the body that are
  closed to the outside and contain the internal
  organs

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BODY CAVITIES
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BODY CAVITIES
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Dorsal Body Cavity

• The space that houses the central nervous system,
  and has two subdivisions the cranial cavity and
  the vertebral cavity
• Cranial cavity is within the skull, and encases
  the brain
• Vertebral, or spinal, cavity is within the
  vertebral column, and encloses the spinal cord

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BODY CAVITIES
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BODY CAVITIES
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Ventral Body Cavity

• Is anterior to and larger than the dorsal cavity
  and has two main subdivisions the thoracic
  cavity, and the abdominopelvic cavity
• Houses the body organs collectively called the
  viscera (viscusan organ in a body cavity), or
  visceral organs
• Thoracic cavity
• Is a superior division of the ventral cavity that
  is further subdivided into the lateral pleural
  cavities that surround the lungs
• Thoracic cavity also contains the medulla
  mediastinum, which includes the pericardial
  cavity surrounding the heart and the space
  surrounding the other thoracic structures
  (esophagus, trachea, and others)
• Diaphragm Muscle separates the Thoracic and
  Abdominopelvic Regions
• Abdominopelvic Regions and Quadrants
• Inferior to the Thoracic Cavity
• There are nine abdominopelvic regions used
  primarily by anatomists
• There are four quadrants used primarily by
  medical personnel

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BODY CAVITIES
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BODY CAVITIES
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Membranes in the Ventral Body Cavity

• The walls of the ventral body cavity and the
  outer surfaces of the organs it contains are
  covered by a thin, double-layered membrane, the
  serosa, or serous membrane
• Serous membranes, or serosae, cover the inner
  walls of the ventral cavity and the outer
  surfaces of organs
• Serous membranes secrete and are separated by a
  thin layer of lubrication fluid called serous
  fluid, which allows organs to slide without
  friction along cavity walls and between each
  other
• Parietal serosa lines the body cavity walls, and
  is named for the specific cavities it is
  associated with
• Visceral serosa covers the outer surfaces of
  organs, and is named for the specific organs it
  is associated with
• Parietal pericardium lines the pericardial cavity
• Visceral pericardium covers the heart within that
  cavity
• Parietal pleura lines the walls of the thoracic
  cavity
• Visceral pleura covers the lungs
• Parietal peritoneum is associated with the walls
  of the abdominalpelvic cavity
• Visceral peritoneum covers most of the organs
  within that cavity

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SEROUS MEMBRANE

• Parietal pericardium lines the pericardial cavity
• Visceral pericardium covers the heart within that
  cavity

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SEROUS MEMBRANE
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Membranes in the Ventral Body Cavity

• You can visualize the relationship between the
  serosal layers by pushing your fist into a limp
  balloon
• The part of the balloon that clings to your fist
  can be compared to the visceral serosa clinging
  to the organs external surface
• The outer wall of the balloon then represents the
  parietal serosa that lines the walls of the
  cavity

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SEROUS MEMBRANE
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Homeostatic Imbalance

• When serous membranes are inflamed, they
  typically produce less lubricating serous fluid
• This leads to excruciating pain as the organs
  stick together and drag across one another, as
  anyone who has experienced pleurisy (inflammation
  of the pleurae thoracic cavity) or peritonitis
  (inflammation of the peritoneal abdominal
  cavity)

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Abdominopelvic Regions

• Because the abdominopelvic cavity is large and
  contains several organs, it helps to divide it
  into smaller areas for study
• Cavity divided into 9 regions
• Umbilical region centermost region deep to and
  surrounding the umbilicus (navel)
• Epigastric region located superior to the
  umbilical region (epiupon, above gastribelly)
• Hypogastric (pubic) region located inferior to
  the umbilical region (hypobelow)

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ABDOMINAL REGION
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ABDOMINAL REGIONS
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Abdominopelvic Regions

• Right and left iliac, or inguinal regions
  located lateral to the hypogastric region
  (iliacsuperior part of the hip
  bone)(inguinalgroin between thigh and trunk)
• Right and left lumbar regions lie lateral to the
  umbilical region (lumbusloin between ribs and
  pelvis)
• Right and left hypochondriac regions flank the
  epigastric region laterally (chondrocartilage)

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ABDOMINAL REGION
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ABDOMINAL REGIONS
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Quadrants

• Medical personnel usually use a simpler scheme to
  localize the abdominopelvic cavity organs
• In this scheme, one transverse and one median
  sagittal plane pass through the umbilicus at
  right angles
• The resulting quadrants are named according to
  their positions from the subjects point of view
• Right upper quadrant (RUQ)
• Left upper quadrant (LUQ)
• Right lower quadrant (RLQ)
• Left lower quadrant (LLQ)

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ABDOMINAL REGION
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Other Body Cavities

• Oral and digestive cavities are continuous
  cavities that extend from the mouth through the
  digestive system to the anus
• Nasal cavity is within and posterior to the nose
• Part of the respiratory system
• Orbital cavities (orbits) in the skull house the
  eyes
• Middle ear cavities are within the skull just
  medial to the eardrums, and house the bones that
  transmit sound vibrations to the inner ears
• Synovial cavities are joint cavities
• Enclosed within fibrous capsules that surround
  movable joints (elbow and knee)
• Lined with a lubricating fluid-secreting
  membranes
• Secrete a lubricating fluid that reduces friction
  as the bones move across one another

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OTHER CAVITIES
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Medical Imaging

• X-ray (radiograph)
• CAT Ccomputerized axial tomography
• Xenon CT
• DSR Dynamic spatial reconstruction
• DSA Digital subtraction angiography
• PET Positron emission tomography
• Sonography (ultrasound imaging)
• MRI Magnetic resonance imaging
• MRS Magnetic resonance spectroscopy

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IMAGING