Organization of the Human Body Essay

Organization of the Human Body Anatomy · Study of the structure and shape of the body and its parts Physiology · Study of how the body and its parts work or function Anatomy: Levels of Study · Gross/Macroscopic Anatomy · Large structures · Easily observable · Regional anatomy · all the structure (muscles, bones, blood vessels, nerves, etc. ) in the particular region of the body, such as the abdomen or leg, are examined. · Systemic anatomy · body structure is studied system by system · Surface anatomy the study of internal structures as they relate to the overlying skin surface · ex: identifying bulging muscles beneath a bodybuilder’s skin · Microscopic Anatomy · Very small structures · Can only be viewed with a microscope · Cytology · considers the cells of the body · Histology · the study of tissues · Developmental Anatomy · traces structural changes that occur in the body throughout the life span · Embryology · concerns developmental changes that occur before birth · Essential tools for studying anatomy: · mastery of anatomical terminology · observation · manipulation palpation (feeling organs with your hands) · auscultation (listening to organ sounds with a stethoscope) Levels of Structural Organization · Chemical level · Simplest level of the structural hierarchy · Atoms (tiny building blocks of matter) combine to form molecules, such as water and proteins. Molecules, in turn, associate in specific ways to form organelles (basic components of the microscopic cells. · Cellular level · Cells have some common function, but individual cells vary widely in size shape because of their unique function · Tissue level Tissues are groups of similar cells that have a common function · The 4 most basic tissue types are epithelium (covers body’s surface and lines cavities), muscle (movement), connective tissue(support & protection for organs), and nervous tissue (rapid internal communication through electrical impulses). · Organ level · An organ is a discrete structure composed of at least 2 tissue types (4 is more common)that performs a specific function for the body.· Organ System level · Organs that work together to accomplish a common purpose · Integumentary System Forms the external body covering, protects deeper tissues from injury · Synthesizes Vitamin D, and houses cutaneous (pain, pressure, etc.

) receptors, sweat & oil glands · Skeletal System · Protects and supports body organs · Provides muscle attachment for movement · Site of blood cell formation · Stores minerals · Muscular System · Produces movement & facial expressions, maintains posture, produces heat · Nervous System · Fast-acting control system · Responds to internal & external change · Activates muscles and glands · Endocrine System Secretes regulatory hormones that regulate growth, metabolism, and reproduction · Cardiovascular System · Transports materials (oxygen, carbon dioxide, nutrients, & wastes) in the body via blood pumped by the heart · Lymphatic System/Immunity · Picks up fluid leaked from blood vessels and returns it to blood. · Disposes of debris in the lymphatic stream · Houses white blood cells (lymphocytes) involved in immunity · The immune response mounts the attack against foreign substances in the body · Respiratory System · Keeps blood supplies with oxygen and removes carbon dioxide The gaseous exchanges occur through the walls of the air sacs in the lungs · Digestive System · Breaks down food & eliminates indigestible material by feces · Allows for nutrient absorption into blood · Urinary System · Eliminates nitrogenous wastes, maintains acid-base balance, regulates water & electrolytes · Reproductive System · Produces offspring · Organismal level · Highest level · The sum total of all structural levels working together to keep us alive Maintaining Life Necessary Life Functions· Maintaining Boundaries · Internal boundaries must remain distinct from the external environment surrounding it · Movement Locomotion, movement of substances · Activities promoted by the muscular system · Substances such as blood or urine are propelled by internal organs · Contractility: the muscle cell’s ability to move by shortening · Responsiveness/Excitability · Ability to sense changes and react (nervous system) · Digestion · Break-down and absorption of nutrients by the blood · Cardiovascular system ; digestive system · Metabolism · Chemical reaction within the body cells · Produce energy ; makes body structures · Breaking down substances into simpler building blocks (catabolism), synthesizing more omplex cellular structures from simpler substances (anabolism), and using nutrients and oxygen to produce (via cellular respiration) ATP. · Depends on digestive and respiratory systems · Excretion · Process of removing wastes from metabolic reactions · Digestive, urinary, ; respiratory systems · Reproduction · Occurs at cellular ; organismal level · Cellular reproduction: one cell divides into two daughter cells for body growth/repair · Produces future generation when sperm unites with egg · Growth · Increase in size of a body part in an organism as a whole Usually accomplished by increasing number ; size of cells Survival Needs · Nutrients · Contain the chemical substances used for energy and cell building · Includes carbohydrates (major energy fuel), proteins, lipids, vitamins, and minerals · Oxygen · Required for chemical reactions · 20% of the air we breathe is oxygen · Water · Accounts for 60-80% of our body · Provides for metabolic reactions ; fluid base for body secretions ; excretions· Normal Body Temperature · 98. 6°F · Appropriate Atmospheric Pressure · The force that air exerts on the surface if the body Breathing and gas exchange in the lungs are dependent upon it Homeostasis · A maintenance of a stable interval environment even though the world is constantly changing · Necessary for normal body functioning and to sustain life · The body communicates through neural and hormonal control systems · Receptors responds to changes in the environment (stimuli) · Sends information to control center · Input flows from the receptor along the so-called afferent pathway · The control center determines the set point, which is the level or range at which a variable is to be maintained. Information then flows from the control center to the effector, along the efferent pathway · The effector provides the means for the control center’s response to the stimulus · The results of the response then feed back to influence the effect of the stimulus, either reducing it (in negative feedback) so that the whole control process is shut off or enhancing it (in positive feedback) so that the process continues more quickly · Negative feedback mechanisms · Includes most homeostatic control mechanisms · Shuts off the original stimulus, or reduces its intensity · Works like a household thermostat Withdrawal reflex · Example of hormonal negative feedback – control of blood sugar by insulin · As blood sugar rises, receptors sense this change and the pancreas (the control center) secretes insulin into the blood. This prompts body cells to absorb more glucose, removing it from the bloodstream · As blood sugar falls, the stimulus for insulin release ends · Positive feedback mechanisms · Increases the original stimulus to push the variable farther· In the body this only occurs in blood clotting and during the birth of the baby · Oxytocin intensifies labor contractions during the birth of a baby by causing hem to be more frequent & powerful · Increased contractions cause more Oxytocin to be released, and so on until the baby is born · The birth ends the stimulus and shits off the positive feedback mechanisms · Blood clotting is a normal response to a break in the wall of a blood vessel. Once a blood vessel has been damages, blood elements called platelets immediately begin to cling to the injured site and release chemicals that attract more platelets.

The growing platelets temporarily plug the tear and initiate the formation of the clot Homeostatic Imbalance · A disturbance in homeostasis results in disease Caused when usual negative feedback mechanisms are overwhelmed and destructive positive feedback mechanisms take over The Language of Anatomy Anatomical Position and Directional Terms · The anatomical reference point is a standard body position called the anatomical position (the body is erect with feel slightly apart). · Directional terms allow us to explain where one body structure is in relation to another. Example: the ears are located on each side of the head, to the right and left of the nose. The ears are lateral to the nose.

Regional Terms · The two fundamental divisions of out body are its axial and appendicular parts. The appendicular part consists of the appendages, or limbs, which are attached to the body’s axis · The axial part, which makes up the main axis of our body, includes the head, neck, and trunk. Body Planes and Sections · A sagittal plane is a vertical plane that divides the body into right and left parts. · A sagittal plane that lies exactly in the midline is called the median plane, or midsagittal plane. · All other sagittal planes, offset from the midline are called parasagittal planes (para=near). · Frontal planes, like sagittal planes, lie vertically. However, they divide the body into anterior and posterior parts.A frontal plane is also called coronal plane.

· A transverse, or horizontal, plane runs horizontally from right to left, dividing the body into superior and inferior parts. A transverse section is also called a cross section. · Oblique sections are cuts made diagonally between horizontal and vertical planes. Body Cavities and Membranes · Dorsal Body Cavity · protects the fragile nervous system organs · Two subdivisions: · Cranial cavity houses the brain · Vertebral, or spinal cavity, houses the spinal cord · The cranial and spinal cavity are continuous with one another · Ventral Body Cavity The more anterior and larger of the closed body cavities · Houses internal organs collectively called viscera, or visceral organs · Two subdivisions · Thoracic cavity · The superior subdivision; surrounded by the ribs and muscles of the chest · Two subdivisions: · Lateral pleural cavities · Each envelope a lung · Medial mediastinum · Contains the pericardial cavity · Encloses the heart and is surrounded by the remaining thoracic organs (esophagus, trachea,; others) · Abdominopelvic cavity · Separated from the Thoracic cavity by the diaphragm, a dome-shaped muscle important in breathing More inferior subdivision · Two parts not physically separated by muscular/membrane wall: · Abdominal cavity · Superior portion · Contains stomach, intestines, spleen, liver, ; other organs · Pelvic cavity · Inferior portion · Lies in the bony pelvis and contains the urinary bladder, some reproductive organs, and the rectum · 2 parts not aligned with each other, bowl-shaped pelvis tips away from the perpendicular · When body is in physical trauma, the Abdominopelvic cavity is most vulnerable because the walls of the abdominal cavity are formed only by trunk muscles and not reinforced by bone Membranes in the Ventral Body Cavity · The walls of the ventral cavity and the outer surface of the organs it contains are covered by thin, double membrane called serosa, or serous membrane· The part of the membrane lining the cavity walls is called the parietal serosa · It folds in half to form the visceral serosa, covering the organs in the cavity · Abdominopelvic Regions ; Quadrants · Right upper quadrant, left upper quadrant, right lower quadrant, right lower quadrant · Umbilical region is the centermost region deep to and surrounding the umbilicus (naval) The epigastric region is located superior to the umbilical region (epi=upon, above, gastric=belly) · The hypogastric (pubic) region is located inferior to the umbilical region (hypo=below). · The right and left iliac, or inguinal, regions are located lateral to the hypogastric region · The right and left lumbar regions lie lateral to the umbilical region · The right and left hypochondriac regions lie lateral to the epigastric region and deep to the ribs Other Body Cavities: Oral ; digestive cavities: commonly called the mouth, is part of and continuous with the cavity of the digestive organs, which opens to the body exterior of the anus.

· Nasal cavity: located within and posterior to the nose, part of the respiratory system passageways · Orbital cavities: in the skull house the eyes and present them in an anterior positions · Middle ear cavities: lie medial to the eardrums, contain tiny bones that transmit sound vibrations to the hearing receptors in the inner ears · Synovial cavities: enclosed within the fibrous capsules that surround freely moveable joints of the body.