Anatomy and Physiology

• Anatomy is the study of the structure of body parts and their relationships.
• Physiology is the study of the function of body parts and how they sustain life.

Subdivisions of Anatomy

• Gross anatomy studies large, visible structures.
• Regional anatomy studies all structures in a specific body area.
• System anatomy studies one system, such as cardiovascular, nervous, or muscular.
• Surface anatomy studies internal structures as they relate to overlying skin.
• Microscopic anatomy studies structures too small to see with the naked eye.
• Cytology is the microscopic study of cells.
• Histology is the microscopic study of tissues.
• Developmental anatomy studies anatomical and physiological development throughout life.
• Embryology studies developments before birth.
• Studying anatomy requires knowledge of anatomical terminology and observational skills.

Maintenance of Life

• Maintaining boundaries involves separating internal and external environments.
• Movement includes locomotion, propulsion, and contractility.
• Responsiveness is the ability to sense and respond to stimuli.
• Digestion is breaking down ingested foodstuffs.
• Metabolism encompasses all chemical reactions in the body.
• Excretion removes wastes from the body.
• Reproduction involves cellular or organismal procreation.
• Growth increases the size of a body part or the organism.

Survival Factors

• Humans need nutrients, oxygen, water, normal body temperature, and appropriate atmospheric pressure.
• These survival factors must be in appropriate amounts.

Homeostasis

• Homeostasis is maintaining stable internal conditions despite environmental changes.
• It is a dynamic state of equilibrium maintained by all organ systems.

Homeostatic Controls

• The nervous and endocrine systems are crucial for maintaining homeostasis.
• Variables are factors that can change, such as blood sugar, body temperature, and blood volume.
• Homeostatic control involves a receptor, control center, and effector.
• The receptor monitors the environment and responds to stimuli.
• The control center determines the set point and appropriate response.
• The effector provides the means to respond, either reducing or enhancing the stimulus.

Negative Feedback

• Negative feedback reduces or shuts off the original stimulus, and is the most common mechanism.
• Body temperature regulation and blood glucose regulation by insulin are examples of negative feedback.
• Receptors detect increased blood glucose, the pancreas secretes insulin, and insulin causes body cells to absorb glucose, lowering blood glucose levels.

Positive Feedback

• Positive feedback enhances or exaggerates the original stimulus.
• It may exhibit a cascade or amplifying effect.
• Positive feedback usually controls infrequent events that do not require continuous adjustment.
• Enhancement of labor contractions by oxytocin and platelet plug formation are examples of positive feedback.

Homeostatic Imbalance

• Disturbance of homeostasis increases the risk of disease and contributes to aging.
• Control systems become less efficient.
• If negative feedback mechanisms are overwhelmed, destructive positive feedback mechanisms may take over.
• Heart failure is an example of a destructive positive feedback mechanism.

Anatomical Position

• Standard anatomical position: body erect, feet slightly apart, palms facing forward with thumbs pointing away from the body.
• Directional terms describe one body structure in relation to another, always based on standard anatomical position.
• Right and left refer to the body being viewed, not the observer's right and left.

Body Planes

• Sagittal plane divides the body vertically into right and left parts.
• Midsagittal plane divides the body perfectly on the midline.
• Parasagittal plane divides the body off-center, not on the midline.
• Frontal (coronal) plane divides the body vertically into anterior and posterior parts.
• Transverse (horizontal) plane divides the body horizontally into superior and inferior parts.
• Oblique section results from cuts at an angle other than 90° to the vertical plane.

Body Cavities

• The body contains internal cavities closed to the environment.
• Cavities provide protection to organs.
• There are two main sets of cavities: dorsal and ventral.

Dorsal Body Cavity

• The dorsal body cavity protects the fragile nervous system.
• It includes the cranial cavity, which encases the brain, and the vertebral cavity, which encases the spinal cord.

Ventral Body Cavity

• The ventral body cavity houses internal organs (viscera).
• It has two subdivisions, which are separated by the diaphragm: thoracic and abdominopelvic.

Thoracic Cavity

• The thoracic cavity includes two pleural cavities, each surrounding one lung.
• The mediastinum contains the pericardial cavity and surrounds other thoracic organs like the esophagus and trachea.
• The pericardial cavity encloses the heart.

Abdominopelvic Cavity

• The abdominopelvic cavity includes the abdominal cavity, containing the stomach, intestines, spleen, and liver.
• The pelvic cavity contains the urinary bladder, reproductive organs, and rectum.

Ventral Body Cavity Membranes

• Serosa (serous membrane) are thin, double-layered membranes in the ventral body cavity.
• Parietal serosa lines internal body cavity walls.
• Visceral serosa covers internal organs (viscera).
• Double layers are separated by a slit-like cavity filled with serous fluid.
• Fluid is secreted by both layers of the membrane.
• Specific serosa names include pericardium (heart), pleurae (lungs), and peritoneum (abdominopelvic cavity).

Other Body Cavities

• Oral and digestive, nasal, orbital, and middle ear cavities are exposed to the environment.
• Synovial cavities (joint cavities) are not exposed to the environment.

Matter

• Matter has mass and occupies space.
• It can exist in solid, liquid, or gas states.
• Weight is mass plus the effects of gravity.

Energy

• Energy is the capacity to do work or put matter into motion.
• It does not have mass or take up space.
• Kinetic energy is energy in action, while potential energy is stored (inactive) energy
• Energy can be transformed from potential to kinetic energy.

Forms of Energy

• Chemical energy is stored in bonds of chemical substances.
• Electrical energy results from the movement of charged particles.
• Mechanical energy is directly involved in moving matter.
• Radiant or electromagnetic energy travels in waves (e.g., heat, visible light, ultraviolet light, and X-rays).

Energy Conversions

• Energy may be converted from one form to another.
• Conversion is inefficient; some energy is "lost" as heat.

Elements

• All matter is composed of elements.
• Elements are substances that cannot be broken down by ordinary chemical methods.
• Carbon, oxygen, hydrogen, and nitrogen make up 96% of the body.

Anatomy is the study of the structure of body parts. Physiology is the study of the function of body parts and how they sustain life. Studying anatomy requires knowledge of anatomical terminology and observational skills.