Anatomy & Physiology: Foundational Concepts and Basic Chemistry

Anatomy and Physiology: Introduction

Definitions and Principle of Complementarity

Anatomy is the study of the structure of body parts and their relationships to one another, while physiology is the study of the function of body parts. The principle of complementarity states that function is dependent on structure, and the form of a structure relates to its function.

• Anatomy: Focuses on body structure.

• Physiology: Focuses on body function.

• Principle of Complementarity: What a structure can do depends on its form.

Topics of Anatomy

• Gross (macroscopic) anatomy: Study of structures visible to the naked eye.

  • Regional anatomy: Study of all structures in a specific body region.

  • Systemic anatomy: Study of body structures by system.

  • Surface anatomy: Study of internal structures as they relate to the skin.

• Microscopic anatomy: Study of structures too small to be seen with the naked eye.

  • Histology: Study of tissues.

  • Cytology: Study of individual cells.

• Developmental anatomy: Study of structural changes throughout the lifespan.

  • Embryology: Study of development before birth.

• Pathological anatomy: Study of structural changes associated with disease.

• Radiographic anatomy: Study of internal structures using specialized imaging techniques.

• Molecular biology: Study of biological molecules.

Topics of Physiology

• Physiology covers the study of how body systems and organs function, often at cellular and molecular levels.

Levels of Structural Organization

Organization from Atoms to Organism

The human body is organized into several levels, each building on the previous one to form the complete organism.

• Chemical level: Atoms combine to form molecules.

• Cellular level: Cells are the basic units of life.

• Tissue level: Groups of similar cells perform a common function.

• Organ level: Organs are made of two or more tissue types performing specific functions.

• Organ system level: Organ systems consist of different organs working together.

• Organismal level: The organism is the sum of all structural levels working together.

Major Organ Systems

The body is comprised of eleven organ systems, each with specific functions:

• Integumentary system: Protects the body, regulates temperature.

• Skeletal system: Supports and protects organs, stores minerals.

• Muscular system: Allows movement, maintains posture.

• Nervous system: Responds to stimuli, coordinates activities.

• Endocrine system: Secretes hormones for regulation.

• Cardiovascular system: Transports blood, nutrients, gases.

• Lymphatic system: Defends against infection, returns fluids to blood.

• Respiratory system: Exchanges gases (oxygen and carbon dioxide).

• Digestive system: Breaks down food, absorbs nutrients.

• Urinary system: Eliminates wastes, regulates water and electrolytes.

• Reproductive system: Produces offspring.

Requirements for Life

Necessary Life Functions

To survive, humans must perform several essential life functions:

• Maintaining boundaries: Separation between internal and external environments.

• Movement: Locomotion and movement of substances.

• Responsiveness: Ability to sense and respond to stimuli.

• Digestion: Breakdown and absorption of nutrients.

• Metabolism: All chemical reactions in the body.

• Excretion: Removal of wastes.

• Reproduction: Production of offspring.

• Growth: Increase in size and number of cells.

Survival Needs

• Nutrients: Chemicals for energy and cell building.

• Oxygen: Required for energy release from food.

• Water: Most abundant chemical in the body.

• Normal body temperature: Needed for chemical reactions.

• Atmospheric pressure: Required for proper gas exchange.

Homeostasis

Definition and Mechanisms

Homeostasis is the ability of the body to maintain a relatively stable internal environment despite external changes.

• Negative feedback: Reduces or shuts off the original stimulus (e.g., regulation of body temperature).

• Positive feedback: Enhances the original stimulus (e.g., blood clotting).

Imbalances in homeostasis can lead to disease.

Homeostatic Control

• Receptor: Detects changes.

• Control center: Determines set point and response.

• Effector: Carries out response.

Basic Chemistry for Anatomy & Physiology

Matter and Energy

Matter is anything that occupies space and has mass. Energy is the capacity to do work and exists as kinetic (movement) or potential (stored) energy.

• Forms of energy:

  • Chemical energy: Stored in chemical bonds.

  • Electrical energy: Movement of charged particles.

  • Mechanical energy: Directly involved in moving matter.

  • Radiant energy: Travels in waves (e.g., light).

• Energy can be converted from one form to another, but some is lost as heat.

Elements and Atoms

Elements are unique substances that cannot be broken down by ordinary means. Atoms are the smallest units of elements, composed of protons, neutrons, and electrons.

• Major elements in the body: Carbon, hydrogen, oxygen, nitrogen (96% of body weight).

• Atomic structure:

  • Nucleus: Contains protons (+) and neutrons (neutral).

  • Electrons: Orbit the nucleus, have a negative charge.

• Atomic number: Number of protons.

• Mass number: Protons + neutrons.

• Isotopes: Atoms with same number of protons, different neutrons.

• Radioisotopes: Unstable isotopes that emit radiation.

Atoms, Molecules, Compounds, and Mixtures

• Molecule: Two or more atoms bonded together.

• Compound: Two or more different atoms bonded together.

• Mixture: Two or more substances physically mixed, not chemically bonded.

• Types of mixtures:

  • Solutions: Homogeneous mixtures (e.g., salt water).

  • Colloids: Heterogeneous mixtures with large particles (e.g., cytoplasm).

  • Suspensions: Mixtures with large, visible solutes that settle out (e.g., blood).

Distinguishing Mixtures from Compounds

• Mixtures can be separated physically; compounds require chemical separation.

• Compounds have chemical bonding; mixtures do not.

Chemical Bonds

Types of Chemical Bonds

• Ionic bonds: Electrons are transferred from one atom to another, forming ions (cations and anions).

• Covalent bonds: Electrons are shared between atoms.

  • Polar covalent: Unequal sharing, creating partial charges.

  • Nonpolar covalent: Equal sharing.

• Hydrogen bonds: Weak attractions between polar molecules, important in water and biological molecules.

Electron Shells and the Octet Rule

• Atoms are stable with eight electrons in their outer shell (octet rule).

Chemical Reactions

Types of Chemical Reactions

• Synthesis: Building larger molecules from smaller ones.

• Decomposition: Breaking down molecules into smaller units.

• Exchange: Both synthesis and decomposition occur.

Chemical Equations

• A chemical equation shows reactants and products, e.g.: $\text{A} + \text{B} \rightarrow \text{AB}$

Reversibility of Chemical Reactions

• Many reactions in the body are reversible, indicated by a double arrow: $\text{A} + \text{B} \rightleftharpoons \text{AB}$

Summary Table: Levels of Organization

Level	Description	Example
Chemical	Atoms combine to form molecules	Water (H2O), Glucose (C6H12O6)
Cellular	Cells are basic units of life	Muscle cell, Neuron
Tissue	Groups of similar cells	Muscle tissue, Nervous tissue
Organ	Two or more tissue types	Heart, Liver
Organ System	Organs working together	Cardiovascular system
Organism	All levels combined	Human body

Summary Table: Types of Chemical Bonds

Bond Type	Description	Example
Ionic	Transfer of electrons, forms ions	NaCl (Sodium chloride)
Covalent	Sharing of electrons	H2O (Water)
Hydrogen	Weak attraction between polar molecules	Between water molecules

Additional info: Academic context and examples have been expanded for clarity and completeness.