Introduction to Anatomy & Physiology

Overview of Anatomy and Physiology

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 explores how these structures function and interact.

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

• Physiology: The study of body function, including how organs and systems work individually and together.

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

Levels of Organization in the Human Body

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

• 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 contains several organ systems, each with specific functions, and is divided into major cavities.

• Major organ systems: Integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary, reproductive.

• Body cavities: Dorsal (cranial and vertebral), ventral (thoracic and abdominopelvic).

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 stable internal conditions despite external changes.

• Feedback loops: Mechanisms that respond to changes in the environment.

• Negative feedback: Reduces the effect of the original stimulus (e.g., regulation of blood glucose).

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

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

Chemistry of Life

Basic Chemical Concepts

Chemistry underpins all physiological processes. Understanding atoms, molecules, and chemical bonds is essential.

• Atoms: Basic units of matter, composed of protons, neutrons, and electrons.

• Elements: Substances made of one type of atom (e.g., C, H, O, N).

• Molecules: Two or more atoms bonded together (e.g., H2O).

• Ions: Atoms or molecules with a net electric charge.

• Types of bonds: Ionic, covalent (polar and nonpolar), hydrogen bonds.

Properties of Water and Solutions

• Water: Universal solvent, high heat capacity, participates in chemical reactions.

• Solution: Homogeneous mixture of solute dissolved in solvent.

• Electrolytes: Substances that dissociate into ions in solution and conduct electricity.

Macromolecules

Macromolecules are large, complex molecules essential for life.

• Carbohydrates: Energy source; monosaccharides, disaccharides, polysaccharides.

• Lipids: Energy storage, cell membrane structure; triglycerides, phospholipids, steroids.

• Proteins: Structure, enzymes, signaling; made of amino acids, form polypeptides.

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

Table: Properties of Selected Molecules

This table compares the hydrophilicity/hydrophobicity and bond types of selected molecules.

Cell Structure and Function

Major Cell Components

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

• Plasma membrane: Phospholipid bilayer with embedded proteins; controls entry and exit of substances.

• Cytoplasm: Jelly-like fluid containing organelles.

• Cytoskeleton: Network of protein filaments for shape and movement.

• Nucleus: Contains genetic material (DNA); controls cell activities.

• Ribosomes: Sites of protein synthesis.

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

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

• Mitochondria: Produce ATP via cellular respiration.

• Lysosomes: Contain digestive enzymes for breakdown of waste.

• Peroxisomes: Detoxify harmful substances.

Plasma Membrane Structure and Function

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

• Membrane proteins: Channels, carriers, receptors, enzymes.

• Carbohydrates: Cell recognition and signaling.

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

Genetic Code and Protein Synthesis

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

• Transcription: DNA is copied into mRNA.

• Translation: mRNA is decoded to build proteins at ribosomes.

Reactions in Cells

Energy and Chemical Reactions

• Potential energy: Stored energy.

• Kinetic energy: Energy of motion.

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

• Catabolic reactions: Break down molecules, release energy (exergonic).

• Anabolic reactions: Build molecules, require energy (endergonic).

Enzymes and Reaction Rates

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

• Factors affecting enzyme activity: Temperature, pH, substrate concentration, enzyme concentration.

• Enzyme specificity: Each enzyme acts on a specific substrate.

• Effect of substrate concentration: As substrate increases, reaction rate increases until saturation.

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: Contracts to produce movement; types include skeletal, cardiac, smooth.

• Nervous tissue: Transmits electrical impulses; includes neurons and neuroglia.

Extracellular Matrix (ECM)

• ECM: Network of proteins and carbohydrates outside cells; provides structural support.

• Components: Collagen fibers, elastic fibers, ground substance.

• Functions: Determines tissue properties, mediates cell signaling.

Specialized Cells and Functions

• Fibroblasts: Produce ECM in connective tissue.

• Adipocytes: Store fat.

• Macrophages: Phagocytose debris and pathogens.

• Chondrocytes: Maintain cartilage.

• Osteocytes: Maintain bone tissue.

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; can impair function.

Sample Questions and Applications

• Feedback mechanisms: Distinguish between positive and negative feedback with examples.

• Bond types: Identify whether a molecule is ionic, polar covalent, or nonpolar covalent, and predict hydrophilicity/hydrophobicity.

• Enzyme function: Predict how changes in temperature, pH, or substrate concentration affect reaction rates.

• Membrane structure: Explain how the phospholipid bilayer affects permeability to different substances.

• Tissue types: Compare and contrast epithelial, connective, muscle, and nervous tissues.

• Clinical relevance: Describe how fibrosis can lead to loss of function in organs.

Additional info: Some explanations and examples have been expanded for clarity and completeness based on standard Anatomy & Physiology curricula.