Introduction to Anatomy and Physiology

Definition and Distinction

Anatomy and physiology are foundational sciences in understanding the structure and function of the human body.

• Anatomy: The study of internal and external body structures and their relationships among other body parts.

• Physiology: The study of how living organisms perform their vital functions.

• Key Difference: Anatomy focuses on structure, while physiology focuses on function.

Body Organization and Regions

Abdominopelvic Quadrants and Regions

The abdominopelvic area is divided for clinical and anatomical reference.

• Quadrants: The abdominopelvic region is divided into four quadrants: right upper, left upper, right lower, and left lower.

• Regions: Alternatively, it can be divided into nine specific regions for more precise localization.

Anatomical Positions

Standardized positions are used to describe locations and directions on the body.

• Anterior: Body viewed from the front.

• Posterior: Body viewed from the back.

• Supine: Body lying face up.

• Prone: Body lying face down.

Homeostasis

Definition and Mechanisms

Homeostasis refers to the continuous processes that establish a relatively stable internal environment.

• Homeostatic Regulatory Mechanism: Consists of a receptor (detects change), a control center (processes information), and an effector (carries out response).

Feedback Loops

• Negative Feedback: Regulation that opposes variation from the norm, maintaining stability (e.g., body temperature regulation).

• Positive Feedback: Regulation that enhances variation from the norm, often driving processes to completion (e.g., blood clotting).

Levels of Organization in the Human Body

Hierarchical Structure

The human body is organized into six levels, each building upon the previous.

• Chemical

• Cellular

• Tissue

• Organ

• Organ Systems

• Organism

Organ Systems

The body contains eleven major organ systems, each with specific functions.

• Integumentary

• Muscular

• Endocrine

• Lymphatic

• Digestive

• Skeletal

• Nervous

• Respiratory

• Cardiovascular

• Urinary

• Reproductive

Subfields of Human Biology

Gross vs. Microscopic Anatomy

• Gross Anatomy: Examines large structures visible to the naked eye.

• Microscopic Anatomy: Examines structures that require magnification, such as cells and tissues.

Body Cavities and Membranes

Major Body Cavities and Their Contents

• Thoracic Cavity: Contains the esophagus, thymus, and the largest vessels of the heart. The pericardial cavity is a membrane surrounding the heart.

• Abdominopelvic Cavity: Contains the stomach, intestines, gallbladder, and other organs. The peritoneal cavity is a membrane lining this area.

• Retroperitoneal Organs: Organs such as the pancreas and kidneys are located behind the peritoneal membrane.

Basic Chemistry for Anatomy & Physiology

Atoms, Molecules, and Compounds

• Atom: The smallest stable unit of matter.

• Elemental Molecule: A pure substance composed of atoms of one kind.

• Compound: A substance composed of two or more atoms of different elements.

Subatomic Particles

Isotopes

• Isotope: Versions of an element that have different numbers of neutrons.

Chemical Bonding

• Atoms interact by forming chemical bonds through the sharing or transfer of their outermost electrons (valence electrons), which are attracted to the positive nucleus of other atoms.

Types of Chemical Bonds

• Polar Covalent: Unequal sharing of electrons between atoms.

• Non-Polar Covalent: Equal sharing of electrons between atoms.

• Ionic: Attraction between oppositely charged ions (cations and anions).

• Hydrogen Bond: Weak attraction between a hydrogen atom in one molecule and an electronegative atom in another.

Properties of Water

Special Properties

• High polarity and ability to form hydrogen bonds.

• High heat capacity and high heat of vaporization.

• Strong cohesion and adhesion.

• High surface tension.

• Lower density as a solid than as a liquid (ice floats).

pH and Acidity

• pH: A logarithmic scale from 0 to 14 that measures the acidity or basicity of an aqueous solution.

• Neutral pH: 7 is considered neutral.

• Acidic solutions: pH less than 7.

• Basic (alkaline) solutions: pH greater than 7.