Introduction to Anatomy & Physiology

Anatomy and Physiology I: Chapter Notes

  • Introduction

    • Anatomy studies the form and structure of the body; Physiology examines how the body functions.

    • Form and function are interrelated; integrating anatomy and physiology is the easiest way to learn both.

    • The relationship: Without thorough knowledge of anatomical structures, a physiologist cannot truly understand the structure’s function.

  • Anatomy: Details of Structure and Form

    • Microscopic anatomy:

    • Examines structures not visible to the unaided eye; specimens are examined under a microscope.

    • Cytology: the study of body cells and their internal structure.

    • Histology: the study of tissues.

    • Gross (macroscopic) anatomy:

    • Investigates structures visible to the unaided eye; specimens are dissected for examination.

    • Divisions:

      • Systemic anatomy: anatomy of each body system.

      • Regional anatomy: structures in a body region.

      • Surface anatomy: superficial markings and internal structures.

      • Comparative anatomy: anatomical similarities and differences across species.

      • Embryology: developmental changes from conception to birth.

  • Physiology: Details of Function

    • Focuses on the function of body structures at molecular and cellular levels.

    • Subdisciplines:

    • Cardiovascular physiology: heart, blood vessels, and blood.

    • Neurophysiology: nerves and nervous system organs.

    • Respiratory physiology: respiratory organs.

    • Reproductive physiology: functioning of reproductive hormones and cycle.

    • Pathophysiology: function of a body system during disease or injury to that system.

  • Integrated Form and Function

    • Anatomy and physiology are interrelated; integrating these disciplines aids learning.

    • Form follows function: anatomical structures are designed to perform their specific functions.

    • A thorough knowledge of anatomy is essential to truly understand physiology.

  • Characteristics of Living Things (Properties common to all organisms)

    • Organization: complex structure and order.

    • Metabolism: sum of all chemical reactions within the body.

    • Anabolism: small molecules joined to form larger ones.

    • Catabolism: large molecules broken down into smaller ones.

    • Growth and development: organisms assimilate materials from the environment; growth and development occur.

    • Responsiveness: ability to sense and react to stimuli.

    • Regulation: adjust internal bodily functions to accommodate environmental changes; maintains homeostasis.

    • Homeostasis: ability to maintain body structure and function.

    • Reproduction: production of new cells for growth, maintenance, and repair; with sex cells, can develop into new organisms.

  • Levels of Organization: from simplest to most complex

    • Chemical level: atoms → molecules → macromolecules → organelles.

    • Cellular level: cells (smallest living structures; basic units of structure and function; formed from chemical level molecules; vary in structure reflecting specialized functions).

    • Tissue level: groups of similar cells performing common functions; four main tissue types: epithelial, connective, muscle, nervous.

    • Organ level: two or more tissue types performing specific functions.

    • Organ system level: related organs working together to achieve a common function.

    • Organismal level: highest level of structural organization; all body systems function interdependently.

  • Anatomic Position

    • Upright stance; feet parallel and flat on the floor; upper limbs at the sides; palms face anteriorly; head level; eyes forward.

  • Sections and Planes

    • Section: actual cut or slice exposing internal anatomy.

    • Plane: imaginary flat surface passing through the body; types:

    • Coronal (frontal) plane: divides body into anterior and posterior parts.

    • Transverse (cross-sectional) plane: divides body into superior and inferior parts.

    • Midsagittal (median) plane: divides body into equal left and right halves.

    • Sagittal plane: parallel to midsagittal; divides structure into unequal left and right portions.

    • Oblique plane: passes through structure at an angle.

  • Anatomic Position and Body Planes (context for orientation)

    • Visual references and terminology used in describing location and direction in the body.

  • Sections from a Three-Dimensional Structure

    • Visuals illustrate how sections reveal internal anatomy from a 3D object. (Refer to Figure 1.5 in the source.)

  • Anatomic Directions

    • Directional terms are used in opposing pairs: anterior/posterior; dorsal/ventral; proximal/distal, etc.

  • Regional Anatomy

    • Axial region: head, neck, and trunk; forms the main vertical axis of the body.

    • Appendicular region: upper and lower limbs.

    • Several regions exist within these two main regions.

  • Regional Terms – Anterior (View) / Posterior (View)

    • Anterior view and posterior view show regional term usage in context.

  • Body Cavities and Membranes (Internal organs housed in enclosed spaces)

    • Body cavities are named according to surrounding structures; grouped into posterior and ventral (anterior) cavities.

    • Posterior aspect: completely encased in bone; cranial cavity (endocranium) houses the brain; vertebral canal houses the spinal cord.

    • Ventral cavity: larger, anteriorly placed; partitioned by the thoracic diaphragm into the superior thoracic cavity and the inferior abdominopelvic cavity.

    • Serous membranes line subdivisions of the ventral cavity; two layers:

    • Parietal layer: lines the internal surface of the body wall.

    • Visceral layer: covers the external surface of organs (viscera).

    • Serous cavity: space between membranes containing serous fluid that lubricates and reduces friction during organ movement.

    • Serous membranes are often described with a balloon analogy: fist represents an organ; balloon represents the serous membrane surrounding it.

  • Specific Body Cavities and Membranes

    • Thoracic cavity spaces:

    • Mediastinum: median space containing heart, thymus, esophagus, trachea, and major vessels.

    • Pericardium: two-layered serous membrane around the heart.

      • Parietal pericardium: outer layer lining the heart sac.

      • Visceral pericardium: on the heart’s external surface.

      • Pericardial cavity: space between parietal and visceral layers containing serous fluid.

    • Pleura: two-layered serous membranes around the lungs.

      • Parietal pleura: lines the thoracic (internal) wall.

      • Visceral pleura: covers the lungs.

      • Pleural cavity: space between layers containing serous fluid.

    • Abdominopelvic cavity spaces:

    • Abdominal cavity: contains most digestive system organs, kidneys, and most of the ureters.

    • Pelvic cavity: inferior region, contains distal large intestine, remainder of ureters, urinary bladder, and internal reproductive organs.

    • Peritoneum: two-layered serous membrane lining the abdominopelvic cavity.

      • Parietal peritoneum: lines the internal walls.

      • Visceral peritoneum: covers the external surface of most abdominal and pelvic organs.

      • Peritoneal cavity: potential space between parietal and visceral layers containing serous fluid.

  • Serous Membranes in Thoracic and Abdominopelvic Cavities

    • Serous membranes create potential spaces for fluid; reduce friction between moving organs and body walls.

    • The thoracic and abdominopelvic cavities feature series of serous membranes (parietal and visceral layers) with serous fluid in between.

  • Abdominopelvic Regions and Quadrants

    • Nine-region plan: partition into nine compartments—Umbilical (central), Epigastric (superior to umbilical), Hypogastric (inferior to umbilical); and Right/Left Hypochondriac, Right/Left Lumbar, Right/Left Iliac regions.

    • Four-quadrant plan (dividing through the umbilicus): Right Upper Quadrant (RUQ), Left Upper Quadrant (LUQ), Right Lower Quadrant (RLQ), Left Lower Quadrant (LLQ).

  • Homeostasis: Keeping Internal Conditions Stable

    • Homeostasis: ability of an organism to maintain a consistent internal environment in response to changing internal or external conditions.

  • Components of Homeostatic Systems

    • Receptor: detects changes in a variable (stimulus).

    • Control center: interprets input from the receptor and initiates changes through an effector.

    • Effector: produces a response that changes the stimulus.

    • The nervous system can provide quicker responses; the endocrine system can provide more sustained responses.

  • Homeostatic Control Mechanisms

    • Negative feedback: the regulatory mechanism that returns the variable to its normal range; the action is in the opposite direction of the stimulus; most processes are regulated this way (e.g., temperature regulation).

    • Positive feedback: stimulus is reinforced to continue moving the variable in the same direction until a climactic event occurs, then the system returns to homeostasis; examples include breastfeeding, blood clotting, and labor.

  • Homeostasis, Health, and Disease (Summary)

    • Homeostatic systems are dynamic; control centers are typically neural or endocrine.

    • Three components: Receptor, Control center, Effector.

    • Negative feedback generally maintains stability; failure can lead to homeostatic imbalance or disease.

  • Clinical View: Establishing Normal Ranges for Clinical Practice

    • Normal ranges for homeostatic variables (based on healthy populations):

    • Body temperature: $$98.6^\