Key Concepts in Physiology

Definitions and Fundamental Terms

This section introduces essential terminology and concepts foundational to the study of Anatomy & Physiology. Understanding these terms is crucial for interpreting physiological mechanisms and experimental design.

• Physiology: The scientific study of the functions and mechanisms occurring in living organisms.

• Pathophysiology: The study of disordered physiological processes associated with disease or injury.

• Teleological vs. Mechanistic: Teleological explanations focus on the purpose of a process ("why"), while mechanistic explanations describe the physical or chemical steps involved ("how").

• Homeostasis: The maintenance of a stable internal environment despite external changes.

• Crossover Study: A type of clinical study where participants receive multiple interventions sequentially, allowing each participant to serve as their own control.

• A Placebo: An inactive substance or treatment used as a control in experiments.

• A Hypothesis: A testable statement predicting the outcome of an experiment.

• A Theory: A well-substantiated explanation of some aspect of the natural world, based on a body of evidence.

• Meta-analysis: A statistical technique that combines results from multiple studies to identify overall trends.

• Dependent vs. Independent Variables: Independent variable is manipulated by the experimenter; dependent variable is measured to assess the effect.

• Glycosylated Molecules: Molecules with carbohydrate groups attached, important in cell recognition and signaling.

• Elements That Make Up More Than 90% of the Body's Mass: Oxygen, carbon, hydrogen, and nitrogen.

Example: In a study testing a new drug, the drug dosage is the independent variable, and blood pressure is the dependent variable.

Biomolecules and Cellular Structure

Structure and Naming of Biomolecules

Biomolecules are the building blocks of cells and tissues. Their structure determines their function in physiological processes.

• Carbohydrate: Organic molecules composed of carbon, hydrogen, and oxygen; primary source of energy.

• Structure of Amino Acids: Amino acids have a central carbon atom bonded to an amino group, carboxyl group, hydrogen atom, and a variable R group.

• Essential Amino Acids: Amino acids that cannot be synthesized by the body and must be obtained from the diet.

• Cations: Positively charged ions (e.g., Na+, K+).

• Structure and Derivative of Fatty Acid: Fatty acids consist of a hydrocarbon chain with a terminal carboxyl group; derivatives include triglycerides and phospholipids.

• ATP: Adenosine triphosphate, the primary energy carrier in cells.

• pH Scale: Measures the concentration of hydrogen ions; scale ranges from 0 (acidic) to 14 (basic).

• Endocrine Glands: Ductless glands that secrete hormones directly into the bloodstream.

• Apoptosis: Programmed cell death, a normal process for removing damaged or unnecessary cells.

Example: Insulin is a hormone produced by the endocrine pancreas that regulates blood glucose levels.

Cell Organelles and Their Functions

Major Cell Organelles

Cell organelles are specialized structures within cells that perform distinct functions necessary for cellular survival and activity.

• Phospholipid Bilayer: Forms the basic structure of cell membranes, providing a barrier and controlling movement of substances.

• Nucleus: Contains genetic material (DNA) and controls cellular activities.

• Nucleoli: Site of ribosomal RNA synthesis within the nucleus.

• Endoplasmic Reticulum (ER): Network of membranes involved in protein and lipid synthesis.

  • Rough ER: Studded with ribosomes; synthesizes proteins for secretion or membrane insertion.

  • Smooth ER: Lacks ribosomes; involved in lipid synthesis and detoxification.

• Golgi Complex: Modifies, sorts, and packages proteins and lipids for delivery.

• Centrioles: Organize microtubules during cell division.

• Ribosomes: Sites of protein synthesis; can be free in cytoplasm or attached to rough ER.

• Mitochondria: Powerhouse of the cell; site of aerobic respiration and ATP production.

• Lysosomes, Peroxisomes: Organelles involved in digestion and detoxification.

• Cytoskeleton: Network of protein filaments providing structural support and facilitating movement.

Example: Muscle cells contain many mitochondria to meet high energy demands.

Cell Junctions and Intercellular Connections

Types of Cell Junctions

Cell junctions are specialized structures that connect adjacent cells, allowing communication and maintaining tissue integrity.

• Tight Junctions: Seal adjacent cells to prevent passage of molecules between them.

• Desmosomes: Anchor cells together, providing mechanical strength.

• Gap Junctions: Allow direct communication between cells through channels.

Example: Gap junctions in cardiac muscle allow rapid transmission of electrical signals for synchronized contraction.

Summary Table: Major Cell Organelles and Their Functions

Additional info: The study guide covers foundational topics from Ch. 1 (Introduction to Physiology), Ch. 2 (Molecular Interactions), and Ch. 3 (Compartmentation: Cells and Tissues), which are essential for understanding later chapters in Anatomy & Physiology.