The Human Body: An Orientation

The Human Body – An Orientation 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

Levels of Structural Organization Figure 1.1

Organ System Overview Integumentary Forms the external body covering Protects deeper tissue from injury Synthesizes vitamin D Location of cutaneous nerve receptors Figure 1.2a

Organ System Overview Skeletal Protects and supports body organs Provides muscle attachment for movement Site of blood cell formation Stores mineral Figure 1.2b

Organ System Overview Muscular Allows locomotion Maintains posture Produces heat Figure 1.2c

Organ System Overview Nervous Fast-acting control system Responds to internal and external change Activates muscles and glands Figure 1.2d

Organ System Overview Endocrine Secretes regulatory hormones Growth Reproduction Metabolism Figure 1.2e

Organ System Overview Cardiovascular Transports materials in body via blood pumped by heart Oxygen Carbon dioxide Nutrients Wastes Figure 1.2f

Organ System Overview Lymphatic Returns fluids to blood vessels Disposes of debris Involved in immunity Figure 1.2g

Organ System Overview Respiratory Keeps blood supplied with oxygen Removes carbon dioxide Figure 1.2h

Organ System Overview Digestive Breaks down food Allows for nutrient absorption into blood Eliminates indigestible material Figure 1.2i

Organ System Overview Urinary Eliminates nitrogenous wastes Maintains acid – base balance Regulates water and electrolytes Figure 1.2j

Overview of Homeostasis Figure 1.4

Homeostatic Control Mechanisms Communication within the body is essential for homeostasis and is accomplished chiefly by the Nervous and Endocrine systems. They use electrical signals delivered by nerves or blood borne hormones as information carriers.

Maintaining Homeostasis Regardless of the factor or event that is being regulated (the Variable), all homeostatic control mechanisms have at least 3 components….. Receptor Sensor that monitors and responds to changes in the environment (stimuli)

Maintaining Homeostasis 2. Control center The sensor responds to stimuli by sending information to control center Information flows from the receptor to the control center via an afferent pathway. (afferent pathway approaches Control Center) Determines the set point at which the variable is to be maintained Analyzes information that is received and then determines appropriate response

Maintaining Homeostasis 3. Effector Provides a means for the Control Center’s response to the stimulus Information flows from the control center to the effector via an efferent pathway. (efferent exits the control center)

Feedback Mechanisms Negative feedback Includes most homeostatic control mechanisms The net effect is to Shut Off the original stimulus, or to reduce its intensity Negative feedback systems include: Body temp, Heart Rate, Blood Pressure, O2, CO2 and Glucose levels Works like a household thermostat

Feedback Mechanisms Negative feedback (cont.) Works like a household thermostat They tend to shut off or reduce the intensity of the stimulus Example: Heart rate and Blood Pressure

Feedback Mechanisms Positive feedback Positive feed back systems are rare in the body! Increases the original stimulus to push the variable farther They tend to have explosive effects In the body this only occurs when blood clots and giving birth

The Language of Anatomy Special terminology is used to prevent misunderstanding Exact terms are used for: Position, Direction, Regions, & Structures It is always assumed that the body is in a “standard” position called the Anatomical Position.

Anatomical Position The body is assumed to be standing, the feet together, the arms to the side, and the head and eyes and palms of the hands facing forwards.

Body Landmarks Anterior Figure 1.5a

Body Landmarks Posterior Figure 1.5b

Orientation and Directional Terms Table 1.1

Orientation and Directional Terms Table 1.1 (cont)

Orientation and Directional Terms Distal Superficial (external) Deep (internal) Table 1.1 (cont)

Body Planes Figure 1.6

Body Cavities Figure 1.7

Abdominopelvic Quadrants Figure 1.8a

Abdominopelvic Regions Figure 1.8b

Abdominopelvic Major Organs Figure 1.8c