Unit 1 – The Human Body: An orientation

Overview of Anatomy and physiology

  • Anatomy--study of body structure; the names of the body parts
  • gross anatomy--general body structures that can be seen with the naked eye
  • microscopic anatomy--cannot be seen with the naked eye
  • cytology--study of cells
  • histology--study of tissues
  • Physiology--study of the functions of the body parts
  • Relationship between anatomy and physiology
  • The structures (anatomy) determine what functions (physiology) take place.

Levels of Structural Organization

  • Atoms  molecules organelles
  • Cells--the basic unit of life
  • Tissues--groups of similar cells working together
  • epithelial tissue--covers the surface of the body and lines the cavities
  • nervous tissue--forms the brain, spinal cord, and nerves
  • connective tissue--used for support (bones and and cartilage), for the attachment of other tissues (tendons, ligaments, and fascia), or for other specialized functions (blood)
  • muscle tissue--moves parts attached to it; skeletal, smooth, cardiac
  • Organs--groups of similar tissues working together
  • Systems--organs working together to perform a specific body function
  • integumentary--protects internal body structures against injury and foreign substances; prevents fluid loss; important in temperature regulation
  • skeletal--supports and protects soft tissues and organs; provides framework; attachments for muscles; produces blood cells
  • muscular--moves body and its parts; maintenance of posture; production of body heat
  • nervous--controls and integrates body activities; responsible for "higher functions" such as thought and reasoning
  • endocrine--regulates body metabolism
  • cardiovascular--transports materials between different cells and tissues
  • immune--protects the body against infection and invasion
  • respiratory--provides for the intake and output of air, as well as the exchange of gases
  • digestive--supplies body with substance (food) from which energy is derived; transports wastes from the body
  • urinary--filters wastes from the blood; helps maintain water and electrolyte balance
  • reproductive--produces gametes; continues the species

Necessary Life Functions

  • Maintaining boundaries
  • “inside” remains distinct from “outside”; cells have cell membrane, body has skin
  • Movement
  • muscular system and movement of substances through internal organs
  • Responsiveness
  • sense and respond to changes in the environment; nervous system
  • Digestion
  • breakdown and delivery of nutrients to the body
  • Metabolism- all chemical reactions within the body
  • Breaking down and building (synthesis) of new molecules
  • depends on the digestive and respiratory systems
  • Excretion
  • elimination of waste from metabolic reactions
  • Involves digestive, urinary, and respiratory system.
  • Reproduction
  • production of offspring (requires sperm and egg)
  • cellular reproduction (mitosis) - produces identical cells for growth or repair
  • Growth
  • increasing of cell size and number

Survival Needs

  • Nutrients (food)- chemicals used for energy and cell building
  • Oxygen required for chemical reactions (cellular respiration) that release energy from food
  • Water
  • makes up 60-80% of our body weight, fluid base for secretions and excretions watery environment necessary for metabolic reactions
  • Body Temperature - around 98°F
  • if body temperature is too high, proteins break down and chemical reactions do not take place
  • Atmospheric Pressure
  • Needed for exchange of gases (carbon dioxide and oxygen) in lungs
  • At high altitudes the atmospheric pressure is lower and the air is thinner making gas exchange more difficult.

Homeostasis

  • Maintenance of a stable internal environment = a dynamic state of equilibrium
  • maintained for normal body functioning
  • involves nervous and endocrine systems
  • Imbalance of homeostasis results in disease
  • A stimulus (stress) that disrupts homeostasis creates a feedback response.
  • Three components of a feedback system:
  • Receptor- responds to changes
  • Control Center- (usually spinal cord, brain or endocrine organ)
  • Assesses changes and produces a response
  • determines set point (normal levels)
  • Effector- body structure which receives the message from control center and produces a change or response
  • Feedback Mechanisms
  • Negative feedback- reduce or stop the original stimulus
  • includes most homeostatic control systems
  • works like a household thermostat
  • example: blood sugar levels
  • Positive Feedback- increase the original stimulus
  • Examples: blood clotting, childbirth

The Language of Anatomy

  • Special terminology used to prevent misunderstanding where exact terms are used for; position, direction, regions and structures
  • Examples:
  • Directional terms- superior means toward the head end
  • Regional Terms- brachial refers to the arm
  • Anatomical position- body is erect with feet parallel and arms hanging at the sides with the palms facing forward.

Body Planes and Sections

  • Sagittal - lengthwise cut dividing the body into right and left parts
  • Frontal – lengthwise cut that divides the body into anterior and posterior parts
  • Transverse- horizontal cut that divides the body or organ into superior and inferior parts, also called a cross-section

Body Cavities

  • Dorsal Body Cavity includes:
  • Cranial cavity- space encased by the skull
  • Spinal cavity- runs within the vertebral column
  • Ventral Body Cavity includes:
  • Thoracic Cavity- includes lungs, heart, and is protected by the rib cage (ends at diaphragm)
  • Abdominopelvic Cavity- stomach, liver, intestines. This cavity can be broken into six distinctive regions:
  • Pelvic Cavity- includes reproductive organs, bladder and rectum