CH1 INTRO ANATOMY

• Anatomy


  The study of the structure of body parts and their relationship to one another
• Physiology


  The study of the function of body parts; how they work to carry out life-sustaining activities
• Subdivisions of anatomy


  • Gross or macroscopic anatomy
  • Regional anatomy
  • System anatomy
  • Surface anatomy
• Subdivisions of microscopic anatomy

  • Cytology: microscopic study of cells
  • Histology: microscopic study of tissues
• Subdivisions of developmental anatomy

  • Embryology: study of developments before birth
• To study anatomy, one must know anatomical terminology and be able to observe, manipulate, palpate, and auscultate
• Subdivisions of physiology


  • Based on organ systems (e.g., renal or cardiovascular physiology)
  • Often focuses on cellular and molecular levels of the body
• To study physiology, one must understand basic physical principles (e.g., electrical currents, pressure, and movement) as well as basic chemical principles
• Principle of complementarity of structure and function

  Function always reflects structure, and what a structure can do depends on its specific form
• Levels of structural organization

  • Chemical level: atoms, molecules, and organelles
  • Cellular level: single cell
  • Tissue level: groups of similar cells
  • Organ level: contains two or more types of tissues
  • Organ system level: organs that work closely together
  • Organismal level: all organ systems combined to make the whole organism
• Necessary life functions


  • Maintaining boundaries
  • Movement
  • Responsiveness
  • Digestion
  • Metabolism
  • Excretion
  • Reproduction
  • Growth
• Maintaining boundaries


  Separation between internal and external environments must exist
• Movement


  Muscular system allows movement of body parts via skeletal muscles, and of substances via cardiac muscle (blood) and smooth muscle (digestion, urination)
• Contractility


  Movement at the cellular level
• Responsiveness


  Ability to sense and respond to stimuli
• Digestion


  Breakdown of ingested foodstuffs, followed by absorption of simple molecules into blood
• Metabolism


  All chemical reactions that occur in body cells, including catabolism (breakdown of molecules) and anabolism (synthesis of molecules)
• Excretion


  Removal of wastes from metabolism and digestion, such as urea, carbon dioxide, and feces
• Reproduction


  At the cellular level, division of cells for growth or repair; at the organismal level, production of offspring
• Growth


  Increase in size of a body part or of organism
• Humans are multicellular, so individual cells must be kept alive by organ systems designed to service the cells
• Survival needs


  • Nutrients
  • Oxygen
  • Water
  • Normal body temperature
  • Appropriate atmospheric pressure
• Nutrients


  Chemicals for energy and cell building, including carbohydrates, proteins, fats, minerals, and vitamins
• Oxygen


  Essential for release of energy from foods; the body can survive only a few minutes without it
• Water


  Most abundant chemical in body, providing the watery environment needed for chemical reactions, as well as fluid base for secretions and excretions
• Normal body temperature


  If body temp falls below or goes above 37°C, rates of chemical reactions are affected
• Appropriate atmospheric pressure


  Specific pressure of air is needed for adequate breathing and gas exchange in lungs
• Homeostasis


  The maintenance of relatively stable internal conditions despite continuous changes in environment; a dynamic state of equilibrium, always readjusting as needed
• Components of homeostatic controls

  • Receptor (sensor)
  • Control center
  • Effector
• Receptor (sensor)


  Monitors environment and responds to stimuli (things that cause changes in controlled variables)
• Control center


  Determines set point at which variable is maintained, receives input from receptor, and determines appropriate response
• Effector


  Receives output from control center and provides the means to respond, either reducing (negative feedback) or enhancing (positive feedback) the stimulus
• Negative feedback


  Most-used feedback mechanism in body, where the response reduces or shuts off the original stimulus, causing the variable to change in the opposite direction of the initial change
• Negative feedback example: Regulation of blood glucose

  1. Receptors sense increased blood glucose

  2. Pancreas (control center) secretes insulin into the blood

  3. Insulin causes body cells (effectors) to absorb more glucose, which decreases blood glucose levels
• Positive feedback


  Response enhances or exaggerates the original stimulus, may exhibit a cascade or amplifying effect
• Positive feedback examples


  • Enhancement of labor contractions by oxytocin
  • Platelet plug formation and blood clotting
• Homeostatic imbalance


  Disturbance of homeostasis that increases risk of disease and contributes to changes associated with aging, where control systems become less efficient and destructive positive feedback mechanisms may take over
• Standard anatomical position


  Body erect, feet slightly apart, palms facing forward with thumbs pointing away from body
• Directional terms


  Describe one body structure in relation to another body structure, based on standard anatomical position
• Major divisions of the body

  • Axial (head, neck, and trunk)
  • Appendicular (limbs - legs and arms)