Anatomy and Physiology Introduction

• Human Anatomy is the study of the body's structures and the relationships among them and relies heavily on memorization.
• Human Physiology is the study of the body's functions and requires conceptual understanding.

Characteristics of Living Organisms

• Cellular Composition underlies the fact that cells are the smallest units that carry out the functions of life.
• Metabolism is the sum of all chemical processes in living organisms.
• Excretion refers to the elimination of potentially harmful waste products that arise from metabolic processes.
• Responsiveness or Irritability is how organisms sense and react to changes or stimuli in their environment.

Structural Organization

• Chemical Level: includes chemicals ranging from tiny atoms to complex molecules.
• Cellular Level of structural organization.
• Organ Level where two or more tissue types combine to form an organ with a recognizable shape that performs a specific function.
• Organ System Level where two or more organs work together to carry out a broad function in the body.

Organ Systems

• The Integumentary System protects the body from the external environment, produces vitamin D, retains water, and regulates body temperature.
• The Skeletal System’s functions are to support the body, protect internal organs, provide leverage for movement, produce blood cells, and store calcium salts.
• The Muscular System's functions are to produce movement, control body openings, and generate heat.
• The Nervous System regulates body functions and provides sensation, movement, automatic functions, and higher mental functions via nerve impulses.
• The Endocrine System regulates body functions by regulating the functions of muscles, glands, and other tissues through the secretion of chemicals called hormones.
• The Cardiovascular System pumps and delivers oxygen-poor blood to the lungs and oxygen-rich blood to the tissues, removes wastes from the tissues, and transports cells, nutrients, and other substances.
• The Lymphatic System returns excess tissue fluid to the cardiovascular system and provides immunity, which is protection against disease.
• The Respiratory System delivers oxygen to the blood, removes carbon dioxide from the body, and maintains the acid-base balance of the blood.
• The Digestive System digests food, absorbs nutrients into the blood, removes food waste, and maintains fluid, electrolyte, and acid-base balance.
• The Urinary System removes metabolic wastes from the blood, maintains fluid, electrolyte, and acid-base balance, and stimulates blood cell production.
• The Male Reproductive System produces and transports sperm, secretes hormones, and facilitates sexual function.
• The Female Reproductive System produces and transports oocytes (eggs), is the site of fetal development, fetal nourishment, childbirth, and lactation, secretes hormones, and facilitates sexual function.

Types of Anatomy and Physiology

• Systemic Anatomy examines individual organ systems.
• Regional Anatomy examines the body in regions, such as the head and neck.
• Surface Anatomy examines surface markings.
• Physiology subfields are classified by organ or organ systems.

Core Principles

• Feedback Loops involve a change in a regulated variable causing effects that "feed back" and in turn affect that same variable.
• Relationship of Structure and Function shows at all levels of organization that the form of a structure is such that it best suits its function.
• Gradients drive many physiological processes.
• Cell-Cell Communication coordinates body functions.

Homeostasis

• Homeostasis is the condition in which the body develops and maintains a relatively stable internal environment.
• Homeostatic imbalances can lead to disease or death if uncorrected.
• Regulated variables in the internal environment are controlled to stay close to a particular normal value, for example, blood sugar.

Feedback Loops

• A change in a regulated variable causes effects that feed back and affects the same variable.
• A series of events that lead to an output.
• The output influences the events of the loops themselves as the loops continue.
• Negative Feedback Loops oppose the initial change and reduce the output.
• Negative Feedback Loops promote stability by negating any stimulus moving a variable away from homeostasis.
• Each variable has a Set Point, which includes a Normal Range.
• The steps of a negative feedback loop are Stimulus, Receptor or Sensor, and Control Center.

Positive Feedback Loops

• Positive Feedback Loops are less common than negative feedback loops and work by increasing the response to a stimulus and reinforcing the initial stimulus.
• They will eventually shut off in response to an external stimulus or some outside event that is not part of the positive feedback loop.
• An example of this is childbirth.

Childbirth Example

• Childbirth begins when a woman goes into labor, an instance of a positive feedback loop.
• The baby's head stretching the cervix acts as the stimulus.
• Data from nerves in the cervix act as receptors and are sent to the brain.
• The brain, also known as the control center, signals the uterus, the effector, to produce the hormone oxytocin, which stimulates uterine contractions.
• This continues until the baby is born, which then stops the feedback loop.
• Pitocin is artificial oxytocin, which can artificially induce labor.

Structure & Function

• The principle of complementarity of structure and function indicates the form of a structure aligns with, and best suits its function, which applies to all levels of organization.

Gradients

• Gradients are present any time more of something exists in one area than another and the two areas are connected.
• Electrical Signals are transmitted between neighboring cells.