Anatomy & Physiology: Core Concepts and Study Guide

Introduction to Anatomy & Physiology

Definitions and Scope

Anatomy and physiology are foundational sciences in understanding the structure and function of the human body. Anatomy focuses on the body's structures, while physiology examines how these structures function.

• Anatomy: The study of body structure, including gross anatomy (visible to the naked eye), microscopic anatomy (histology), and cytology (study of cells).

• Physiology: The study of how body parts function and work together to sustain life.

• Histology: The study of tissues at the microscopic level.

Levels of Organization

The human body is organized into hierarchical levels, each with increasing complexity.

• Chemical level: Atoms and molecules

• Cellular level: Cells and their organelles

• Tissue level: Groups of similar cells performing a common function

• Organ level: Two or more tissue types working together

• Organ system level: Organs working together for a common purpose

• Organismal level: The complete living being

Body Systems and Cavities

The human body is divided into several organ systems, each with specific functions. Major body cavities include the cranial, thoracic, abdominal, and pelvic cavities.

• Examples of organ systems: Skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary, and reproductive systems.

Homeostasis and Feedback Mechanisms

Homeostasis is the maintenance of a stable internal environment. The body uses feedback loops to regulate physiological processes.

• Homeostasis: The body's ability to maintain relatively stable internal conditions despite external changes.

• Feedback loops: Mechanisms that detect changes and initiate responses to restore balance.

• Negative feedback: Reduces or shuts off the original stimulus (e.g., regulation of blood glucose by insulin).

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

• Key components: Variable, set point, receptor/sensor, control center, effector, response.

Chemistry of Life

Basic Chemical Concepts

Chemistry underlies all physiological processes. Understanding atoms, molecules, and chemical bonds is essential for studying biology.

• Atom: The smallest unit of an element, composed of protons, neutrons, and electrons.

• Molecule: Two or more atoms bonded together.

• Ions: Atoms or molecules with a net electric charge due to loss or gain of electrons.

• Covalent bond: Atoms share electrons.

• Ionic bond: Transfer of electrons from one atom to another, resulting in charged ions.

• Polar molecule: Unequal sharing of electrons, resulting in partial charges (e.g., water).

• Nonpolar molecule: Equal sharing of electrons, no partial charges.

Water and Solutions

• Solution: A homogeneous mixture of two or more substances.

• Solvent: The substance present in the greatest amount (usually water in biological systems).

• Solute: The substance dissolved in the solvent.

Macromolecules

Macromolecules are large, complex molecules essential for life.

• Carbohydrates: Provide energy and structural support. Examples: glucose, glycogen.

• Lipids: Store energy, form cell membranes, and act as signaling molecules. Examples: triglycerides, phospholipids, steroids.

• Proteins: Perform a wide range of functions, including catalysis (enzymes), structure, transport, and signaling. Composed of amino acids.

• Nucleic acids: Store and transmit genetic information. Examples: DNA, RNA.

Table: Properties of Selected Molecules

Molecule	Hydrophilic or Hydrophobic	Covalent or Ionic	Polar or Nonpolar (if covalent)
LiF	Hydrophilic	Ionic	—
NH3	Hydrophilic	Covalent	Polar
NF3	Hydrophilic	Covalent	Polar
CaCl2	Hydrophilic	Ionic	—
CH4	Hydrophobic	Covalent	Nonpolar

Cell Structure and Function

Major Cell Components

Cells are the basic units of life, each containing specialized structures called organelles.

• Plasma membrane: Phospholipid bilayer that controls entry and exit of substances.

• Cytoplasm: Jelly-like fluid inside the cell containing organelles.

• Cytoskeleton: Network of protein filaments providing structural support.

• Nucleus: Contains genetic material (DNA).

• Ribosomes: Sites of protein synthesis.

• Endoplasmic reticulum (ER): Rough ER synthesizes proteins; smooth ER synthesizes lipids and detoxifies chemicals.

• Golgi apparatus: Modifies, sorts, and packages proteins and lipids.

• Mitochondria: Produce ATP through cellular respiration.

• Lysosomes: Contain digestive enzymes to break down waste.

• Peroxisomes: Detoxify harmful substances.

Plasma Membrane Structure and Function

• Phospholipid bilayer: Hydrophilic heads face outward; hydrophobic tails face inward.

• Proteins: Serve as channels, carriers, receptors, and enzymes.

• Carbohydrates: Attached to proteins and lipids on the extracellular surface; involved in cell recognition.

• Selective permeability: Allows some substances to cross more easily than others.

Genetic Code

• Genetic code: The sequence of nucleotides in DNA that determines the amino acid sequence of proteins.

• Changes (mutations) in DNA can alter protein structure and function.

Reactions in Physiology

Energy and Chemical Reactions

• Potential energy: Stored energy.

• Kinetic energy: Energy of motion.

• Activation energy: Minimum energy required to start a chemical reaction.

• Catabolic reactions: Break down molecules, releasing energy (e.g., cellular respiration).

• Anabolic reactions: Build larger molecules from smaller ones, requiring energy (e.g., protein synthesis).

Enzymes

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

• Enzyme activity can be affected by temperature, pH, substrate concentration, and inhibitors.

• Lock-and-key model: Substrate fits into the enzyme's active site.

Histology: Tissues and Extracellular Matrix

Types of Tissues

• Epithelial tissue: Covers surfaces, lines cavities, forms glands.

• Connective tissue: Supports, binds, and protects organs (includes bone, cartilage, adipose, blood).

• Muscle tissue: Responsible for movement (skeletal, cardiac, smooth).

• Nervous tissue: Transmits electrical impulses (neurons and glial cells).

Extracellular Matrix (ECM)

• ECM: Network of proteins and carbohydrates outside cells, providing structural and biochemical support.

• Ground substance: Gel-like material in ECM.

• Collagen fibers: Provide strength and flexibility.

• Elastic fibers: Allow tissues to stretch and recoil.

Cell Types in Connective Tissue

• Fibroblasts: Produce fibers and ground substance.

• Adipocytes: Store fat.

• Macrophages: Engulf pathogens and debris.

• Chondrocytes: Found in cartilage.

• Osteocytes: Found in bone.

Membranes and Tissue Repair

• Serous membranes: Line body cavities not open to the outside; secrete serous fluid.

• Mucous membranes: Line cavities open to the outside; secrete mucus.

• Fibrosis: Replacement of normal tissue with scar tissue, which can impair function.

Sample Study Questions

• How does a negative feedback loop differ from a positive feedback loop?

• What is the difference between an ionic and a covalent bond?

• How do hydrogen bonds differ from polar covalent bonds?

• What makes a nonpolar covalent molecule hydrophobic?

• What is the main role of carbohydrates in the body? In what form are carbohydrates stored?

• Why is the genetic structure of proteins important?

• How is the structure of the plasma membrane related to its function?

• Compare and contrast catabolic and anabolic reactions.

• What are the key differences between epithelial and connective tissues?

• What is a key property that returns shape within muscle cells?

• What are the key differences between a serous membrane and a mucous membrane?

• Why can fibrosis lead to the loss of function in an organ?

Additional info:

• Some explanations and examples have been expanded for clarity and completeness.

• Table entries and some definitions are inferred from standard Anatomy & Physiology content.