Anatomy & Physiology: Introduction and Core Concepts

Anatomy and Physiology Defined

• Anatomy: The study of body parts and their relation to each other.

• Physiology: The study of how body parts work and interact, focusing on organ function and processes.

• Structure and Function: Structure determines function; physiological needs are fulfilled by anatomical structure.

Levels of Organization

• Organized with boundaries (macroscopic to microscopic levels)

• Movement and transformation of energy

• Responsiveness to environmental changes

• Growth and development over time

• Homeostasis: Maintaining internal stability

Gross vs. Microscopic Anatomy

• Gross Anatomy: Study of large, visible structures (e.g., organs, muscles)

• Microscopic Anatomy: Study of structures only visible with a microscope (e.g., cells, tissues)

Requirements for Life

What Do Humans Need to Be Alive?

• Nutrients: Carbohydrates, proteins, fats, vitamins, minerals, oxygen, and water are essential for energy and cellular processes.

• Oxygen: Required for metabolic and chemical reactions, especially for ATP production.

• Water: Most abundant chemical in the body; acts as a solvent and medium for chemical reactions.

• Normal Body Temperature: Enzymes and cellular processes function optimally at ~37°C.

• Normal Atmospheric Pressure: Necessary for proper lung function and gas exchange.

Boundaries and Responsiveness

• Boundaries: Plasma membranes and skin protect internal environments from external threats (e.g., pathogens, chemicals).

• Responsiveness/Excitability: Ability to sense and respond to stimuli (e.g., nervous system response to changes in environment).

Metabolism, Digestion, Excretion, Reproduction, and Growth

• Metabolism: All chemical reactions in the body, including catabolism (breakdown) and anabolism (synthesis).

• Digestion: Breakdown of food into absorbable units.

• Excretion: Removal of waste products (e.g., urea, carbon dioxide, feces).

• Reproduction: Cellular (mitosis) and organismal (production of offspring).

• Growth: Increase in size and number of cells; some tissues can regenerate.

Homeostasis and Feedback Mechanisms

Homeostasis

• Maintenance of a relatively stable internal environment despite external changes.

• Requires constant monitoring and regulation (energy-intensive).

Components of Homeostatic Control

• Receptor: Detects changes (stimuli).

• Control Center: Processes information and determines response.

• Effector: Carries out the response to restore balance.

Types of Feedback

• Negative Feedback: Response reduces or shuts off the original stimulus (e.g., body temperature regulation).

• Positive Feedback: Response enhances the original stimulus (e.g., childbirth, blood clotting).

• Feedforward: Anticipatory response to expected changes (e.g., salivation when smelling food).

Law of Mass Balance

• In a steady state, the total amount of a substance in the body remains constant unless added or removed.

Basic Chemistry for Physiology

Valence Electrons and Chemical Bonds

• Valence electrons are the outermost electrons involved in chemical interactions.

• Number of valence electrons determines chemical properties and bonding behavior.

Major Elements in the Human Body

Common Elements and Their Functions

• Calcium: Bones, teeth, muscle contraction, nerve impulses

• Phosphorus: Nucleic acids, ATP

• Potassium: Nerve cells

• Sulfur: Protein component

• Sodium: Maintains extracellular fluid balance

• Chlorine: Maintains extracellular fluid balance

• Magnesium: Enzyme cofactor

• Iodine: Thyroid hormone production

• Iron: Oxygen transport, enzyme cofactor

Major Organic Compounds

• Lipids

• Carbohydrates

• Proteins

• Nucleic Acids

Molecules, Compounds, and Mixtures

• Molecule: Two or more atoms bonded together.

• Compound: Two or more different kinds of atoms bonded together.

• Mixtures: Physical combinations of substances (solutions, colloids, suspensions).

Chemical Reactions in Physiology

Types of Chemical Reactions

• Synthesis: Combining smaller molecules to form larger ones (anabolic).

• Decomposition: Breaking down larger molecules into smaller ones (catabolic).

• Exchange: Combination of synthesis and decomposition.

Factors Affecting Reaction Rates

• Temperature: Higher temperature increases reaction rate.

• Concentration: Higher reactant concentration increases rate.

• Particle Size: Smaller particles react faster.

• Catalysts/Enzymes: Lower activation energy, increase reaction rate.

Enzymes

• Biological catalysts that speed up reactions by lowering activation energy.

• Highly specific for their substrates.

• Optimal activity at body temperature (~37°C).

• Examples: Lactase (breaks down lactose), DNA polymerase (facilitates DNA replication).

Properties of Water and pH

Water's Importance

• High heat capacity and heat of vaporization: Stabilizes body temperature.

• Polar solvent: Dissolves ionic substances, forms hydration shells.

• Reactivity: Involved in hydrolysis and dehydration reactions.

• Cushioning: Protects organs from physical trauma.

Water as a Dipolar Molecule

• Oxygen attracts electrons more strongly than hydrogen, creating polarity.

• Hydrogen bonds form between water molecules, contributing to its unique properties.

Water as an Acid and a Base

• Can both accept and donate protons (H+).

pH Scale

• Measures concentration of hydrogen ions [H+] in solution.

• Acidic: High [H+], pH < 7

• Alkaline (basic): Low [H+], pH > 7

• Buffers: Resist changes in pH (e.g., bicarbonate buffer in blood).

Cell Biology: Transfer of Biological Information & Cell Cycle Basics

Advantages of Multicellularity

• Increased size and complexity

• Division of labor (specialization of cells)

• Increased lifespan (organism can survive loss of individual cells)

Cells of the Human Body

• Highly specialized for different functions

• Complex internal structure and organization

Additional info:

• Some content inferred for completeness, such as the role of buffers and the importance of cell specialization in multicellular organisms.