The Human Body

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The Human Body

• An Overview

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Anatomy

• From Latin tomy (to cut) and ana (apart)
• Its the study of structure and shape of the body
  and its parts
• Two types
• Gross anatomy large structures, easily
  observable
• Microscopic anatomy small structures only
  visible with microscope

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Gross Anatomy
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Microscopic anatomy
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Levels of Structural Organization
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• Structural complexity
• Six levels of complexity
• Chemical level
• Atoms smallest building blocks of matter
• Molecules combinations of atoms to make water,
  sugars, and proteins
• Atoms combine to form molecules

Nitrogen
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• Cellular level
• Molecules combine to form cells, which vary in
  size and shape, reflecting different functions of
  body

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• Tissue level
• Similar types of cells group to form tissues
• Four basic tissue types
• Epithelial tissue (skin, membranes)
• Connective tissue (tendons, cartilage, ligaments
  and bone)
• Muscular tissue (muscles)
• Neural tissue (spinal cord, brain matter)

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• Organ level
• Tissue or multiple tissues that form a structure
  that performs a specific function
• Ex small intestine is made out of all four
  tissue types

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• Organ system level
• Group of organs that cooperate to accomplish a
  common purpose
• Ex digestive system includes esophagus, stomach,
  small and large intestines, and more
• Total of 11 organ systems
• How they work physiology!

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• Organismal level
• Highest level of organization
• Human organisms have similar organ systems and
  chimpanzees, but very different organ systems
  than mosquitoes

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Physiology

• Studies functions (how it works) of human body
  and its parts
• Anatomists observe structures while physiologists
  employ experimentation

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Organ systems

• Integumentary system
• External covering of the body (skin)
• Protects deeper tissue from injury or infection
• Synthesizes vitamin D
• excretes salts and urea in perspiration
• helps regulate body temperature
• contains pain, temperature, and pressure
  receptors for environmental cues

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• Muscular system
• Muscles of body
• Contract or shorten to move skeleton
• Maintains posture
• Produces heat

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• Skeletal system
• All bones, cartilages, ligaments and joints make
  up skeletal system
• Protects and supports body organs
• Provides muscle attachment for movement
• Forms blood cells (hematopoiesis) in bone marrow
• Provides and stores minerals

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• Nervous system
• Brain, spinal cord, nerves, and sensory receptors
• Speedy control system that responds to external
  stimuli
• Light
• Sound
• Temperature changes
• Pain
• Pressure
• Central nervous system (brain and spinal cord)
  assesses information and responds by activating
  appropriate effector (muscles or glands)

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• Endocrine system
• A series of glands that slowly control body by
  producing and releasing hormones for growth,
  metabolism, and reproduction
• Pituitary gland
• Thyroid gland
• Parathyroid glands
• Adrenal glands
• Thymus
• Pancreas
• Pineal gland
• Ovaries (females)
• Testes (males)

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• Cardiovascular system
• Heart and blood vessels
• Work together to transport materials in blood
• Nutrients
• Hormones
• Oxygen
• Carbon dioxide
• Waste

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• Lymphatic system
• Lymphatic vessels, lymph nodes, spleen, and
  tonsils
• Returns fluid leaked from blood back to blood
  vessels
• Lymph nodes (and others) help cleanse blood and
  store cells involved in immunity

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• Respiratory system
• Lungs, nasal passages, pharynx, larynx, trachea,
  and bronchi
• Supplies oxygen
• Removes carbon dioxide

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• Digestive system
• Mouth, esophagus, stomach, small and large
  intestines, liver, pancreas, and rectum
• Breaks down food
• Deliver products to blood for dispersal to body
• Undigested food leaves body through anus as feces
• Reclaim water for bodily use

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• Urinary(excretory) system
• Kidneys, ureters, bladder, urethra
• Rids body of waste products
• Nitrogen-containing urea and uric acid from
  breakdown of proteins and nucleic acids
• Maintains bodys water and salt/electrolyte
  balance
• Regulates acid-base balance of blood

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• Reproductive system
• Males scrotum, penis, accessory glands, and
  ducts
• Females ovaries, uterine tubes, uterus, and
  vagina
• Sole purpose is to produce offspring

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Major Organs
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Life Functions

• Organ systems work together to promote health and
  well-being of entire body. Must be able to
  provide eight functions necessary for living. A
  healthy body must

HINT these are all VERBS!
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Maintain boundaries

• The inside remains distinct from the outside.
  
• Examples include
• a cells environment maintained by the cell
  membrane
• the integumentary system protecting organs from
  desiccating (drying out), from bacteria and
  viruses, from heat and sunlight, and from
  chemicals

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Move

• Muscle movement is necessary for
• Locomotion getting us from one place to another,
  or for moving muscle for safety (hot stove)
• Movement of substances getting blood, food, and
  urine through their proper organs

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Respond or be irritated

• Ability to sense changes (from stimuli) and react
  to them
• Ex is automatically removing hand from broken
  glass (painful stimulus) that cuts involuntary
  response
• Ex when decrease in oxygen levels detected
  (mountains), response is to increase breathing
  rate to obtain more oxygen

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Digest

• Breakdown of nutrients and absorption into blood
  for delivery to all body cells

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Metabolize

• Chemical reactions within body cells to
• Produce energy in form of ATP (adenosine
  triphosphate)
• Make body structures like bones and muscles
• Regulated mainly by hormones secreted by glands
  of endocrine system

testosterone
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Excrete

• Eliminate excreta (waste) from digestions and
  metabolic reactions

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Reproduce

• Produce future generations
• of identical cells in cell division (repair or
  growth)
• of entire organism

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Grow

• Increasing cell size and number
• Must make more cells faster than cells die

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Survival needs
HINT these are all NOUNS!

• In order to maintain the eight functions for
  living, the human body must have the following
  items
• Nutrients
• Chemicals for energy and cell building
• Carbohydrates
• Proteins
• Lipids
• Vitamins
• Minerals

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• Oxygen
• Required for chemical reactions
• Cellular respiration

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• Water
• 60-80 of body weight
• Necessary for metabolic reactions

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• Basal body temperature
• 98.6F or 37C
• Atmospheric pressure
• Standard atmospheric pressure (on earth at sea
  level is 760 mmHg or 29.92 inHg)

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Homeostasis

• Maintenance of a stable internal environment a
  dynamic state of equilibrium
• Homeostasis must be maintained for normal body
  functioning and to sustain life
• When needs are being adequately met, body is
  functioning smoothly, body demonstrates
  homeostasis
• All organ systems partake in maintaining
  homeostasis

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• Homeostatic imbalance a disturbance in
  homeostasis sets off chain reaction of events
• Stimulus
• Produces change in variable
• Detection
• Change is detected by receptor
• Input
• Information is sent from receptor to control
  center
• Output
• Control center decides what action or response
  should be taken
• Response
• Action or response feeds back to influence
  magnitude of stimulus and returns variable to
  homeostasis

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Overview of Homeostasis
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• The body communicates chiefly through nervous and
  endocrine systems
• Nervous uses electrical signals delivered by
  nerves
• Endocrine system uses blood borne hormones
• Factor being regulated is called the variable

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• All homeostatic control mechanisms have at least
  three components
• Receptor
• Responds to changes in the environment (stimuli)
• Sends information to control center via afferent
  pathway
• Afferent approaches control center
• Control center
• Determines set point at which variable should be
  maintained
• Analyzes information
• Determines appropriate response
• Effector
• Provides a means for response to the stimulus
• Desired response flows along efferent pathway
• Efferent exits control center

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• Most homeostatic control mechanisms are negative
  feedback mechanisms
• Negative feedback
• Includes most homeostatic control mechanisms
• Shuts off the original stimulus, or reduces its
  intensity
• Works like a household heating system with set
  point of 72F
• If its too cold, will heat it up by turning on
  heater
• If its too warm, will shut off heater until it
  levels off

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• Hypothalamus, located in brain, regulates body
  temperature

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• If stimulus produces desired effect, and body
  needs it to increase in action, a positive
  feedback results
• Positive feedback
• Increases the original stimulus to push the
  variable even farther away from set point
• In the body this only occurs in blood clotting,
  birth of a baby, and protein digestion
• Cut on hand stimulus (wasnt there prior and is
  not part of body set-point)
• Factor in blood starts to form blood clots
• Body wants MORE blood clots so positive feedback
  mechanism takes over
• MORE blood clotting factors are in play until
  wound heals

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• Homeostasis is SO important that most disease is
  a result of homeostatic imbalance
• As we age, body organs become less efficient, and
  internal conditions less stable
• Events put us at increased risk for illness and
  produce changes associated with aging
• Ex elastin in connective tissue of skin makes it
  able to resume shape after stretching, like a
  rubber band
• As we age, elastin production decreases and/or
  breaks down, so skin loses ability to resume
  shape

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Anatomical Language

• Cant always describe body as left and right or
  top and bottom because so many protrusions and
  bends. Have specific terminology to describe
  locations of the body.
• Exact terms are used for
• Positions
• Directions
• Regions
• Structures

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• Positions
• Initial point of reference is always the standard
  position called anatomical position regardless of
  position body happens to be in (like sitting)
• Body standing erect
• Feet parallel
• Arms hanging at sides, palms facing forward
• Two major positions
• Anterior front of body in anatomical position
• Posterior back of body in anatomical position

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• Regions
• Anterior body landmarks
• See page 13 of book (dont need to know for test)

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• Posterior body landmarks
• See page 13 of book (dont need to know for test)

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• Directions
• Used to describe body structure is in relation to
  another.
• Superior toward head
• Inferior away from head below
• Anterior toward or at front in front of
• Posterior toward or at back behind
• Medial toward or at midline
• Lateral away from midline
• Intermediate between a more medial and more
  lateral structure

opposites
opposites
opposites
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• Proximal close to origin of body part or point
  of attachment of a limb to the body trunk
• Distal farther from origin of a body part or
  point of attachment of a limb to the body trunk
• Superficial toward or at body surface
• Deep away from body surface more internal
• Supine lying face upwards
• Prone lying face down

opposites
opposites
opposites
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• Structures
• Planes and sections
• Midsagittal
• Frontal
• Transverse

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• Body cavities