Major Themes of Anatomy & Physiology

Definitions and Scope

Anatomy and Physiology (A&P) are foundational sciences that study the structure and function of the human body. Anatomy focuses on the physical structures, while physiology examines the dynamic processes that occur within living organisms.

• Anatomy: The study of the structure of the body. Views the body as a set of interconnected structures.

• Physiology: The study of dynamic processes in the living body. Views the body as a set of interconnected processes.

• Integration: Structure and function are intertwined; understanding their relationship is essential for studying the human body.

Anatomy

Methods of Study

Anatomy can be learned through various methods, including dissection, palpation, auscultation, and medical imaging. These techniques help visualize and understand body structures.

• Dissection: Cutting and separating tissues to reveal relationships.

• Palpation: Feeling structures with hands.

• Auscultation: Listening to body sounds (e.g., heart, lungs).

• Percussion: Tapping and listening for sounds indicating structure.

Medical Imaging Techniques

• Radiography (X-rays): Absorbed by dense structures; shows only 2D images, so pictures may overlap.

• Computed Tomography (CT scans): Uses low-intensity X-rays; images thin sections, allowing visualization of soft and hard tissues.

• Magnetic Resonance Imaging (MRI): Uses powerful electromagnetic fields; useful for visualizing soft tissue.

• Positron Emission Tomography (PET scan): Assesses metabolic state of tissue; uses radioactively labeled glucose.

Levels of Human Structure

• Organism → Organ system → Tissue → Cells → Organelles → Molecules → Atoms

Physiology

Criteria that Define Life

Physiology studies the processes that allow organisms to live and adapt. Several criteria define living things:

• Organization: Complex structure and order.

• Cells: Basic unit of life.

• Development: Change over time.

• Excitability: Ability to sense and react to stimuli.

• Reproduction: Ability to produce offspring.

• Evolution: Genetic change from one generation to the next.

• Homeostasis: Maintenance of internal stability.

Homeostasis

• Maintains physiological values within a narrow range (dynamic equilibrium).

• Uses negative feedback mechanisms to reverse changes and maintain stability.

• Example: Blood pressure regulation – when blood pressure drops, blood vessels relax and heart rate rises; when blood pressure rises, blood vessels tighten and heart rate falls.

• Positive feedback: Leads to greater change in the same direction (e.g., childbirth intensifies contractions until delivery).

Chemistry of Life

Acids, Bases, and pH

Chemical reactions in the body depend on the balance of acids and bases, measured by pH.

• Acid: Any protein donor (releases H+).

• Base: Any proton acceptor (accepts H+).

• pH scale:

• Blood pH is 7.35–7.45; deviations can cause serious effects.

Carbohydrates

• Monosaccharides: Simple sugars (e.g., glucose, fructose, galactose).

• Disaccharides: Two monosaccharides bonded (e.g., sucrose = glucose + fructose).

• Polysaccharides: Long chains of glucose (e.g., glycogen, starch, cellulose).

• Primary source of energy storage; also found in cell membranes and tissues.

Lipids

• Composed of carbon, hydrogen, and oxygen; hydrophobic.

• Triglycerides: Fats and oils; energy storage, insulation, cushioning.

• Phospholipids: Major component of cell membranes; amphipathic.

• Steroids: Cholesterol-based; hormones (e.g., cortisol, testosterone).

Proteins

• Polymers of amino acids; 20 varieties, each with an amino group, carboxyl group, and R group.

• Peptide chains: Long chains of amino acids; structure and function determined by DNA.

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

• Enzyme reaction: (Enzyme + Substrate = Enzyme-Substrate complex = Enzyme + Product)

Nucleic Acids

• Polymers that serve as the cell's genetic machinery.

• DNA: Deoxyribonucleic acid; stores genetic information.

• RNA: Ribonucleic acid; translates DNA into proteins.

• Nucleotides: Monosaccharide, phosphate group, nitrogenous base.

• Nitrogenous bases: Cytosine, Thymine, Uracil, Adenine, Guanine (C, T, U, A, G).

• DNA: A, T, C, G; RNA: A, U, C, G.

• ATP: Adenosine triphosphate; energy currency of the cell.

The Cell

General Structure

The human body contains approximately 200 types of cells, each with specialized functions, shapes, and sizes.

• Plasma membrane: Cell surface boundary; regulates entry and exit of substances.

• Cytoplasm: Material between plasma membrane and nucleus; contains organelles.

Major Cell Components

• Membrane proteins: Integral (span membrane) and peripheral (surface only); perform various functions such as transport, signaling, and cell adhesion.

• Cell surface extensions: Microvilli (increase surface area), cilia (movement), flagella (motility), pseudopods (cytoplasmic extensions).

• Cell junctions: Connections between cells; tight junctions (prevent leakage), desmosomes (mechanical strength), gap junctions (communication).

Cell Interior

• Cytoskeleton: Microfilaments, intermediate filaments, microtubules; provide structure and movement.

• Organelles: Specialized structures with specific functions:

  • Nucleus: Contains DNA; control center.

  • Endoplasmic reticulum (ER): Rough (protein synthesis), smooth (lipid synthesis).

  • Ribosomes: Protein synthesis; found on rough ER and in cytoplasm.

  • Golgi complex: Modifies, packages, and ships proteins.

  • Lysosomes: Digestive enzymes; break down waste.

  • Peroxisomes: Break down fatty acids; neutralize free radicals.

  • Mitochondria: Produce ATP; "powerhouse" of the cell.

  • Centrioles: Cell division; form spindle fibers.

Cell Cycle

• Phases: Interphase (G1, S, G2), Mitosis (prophase, metaphase, anaphase, telophase), cytokinesis.

Transport Through Cellular Membranes

• Filtration: Physical pressure drives fluid through a selectively permeable barrier.

• Simple diffusion: Particles move down a concentration gradient.

• Osmosis: Diffusion of water across a membrane.

• Carrier-mediated transport: Uses proteins to move substances; includes facilitated diffusion and active transport (requires ATP).

• Vesicular transport: Endocytosis (into cell), exocytosis (out of cell).

Genes and Cellular Function

DNA Structure and Function

DNA contains genetic instructions for protein synthesis. Genes are segments of DNA that code for specific proteins.

• Chromatin: DNA and associated proteins; condenses to form chromosomes during cell division.

• Central Dogma: DNA → RNA → Protein

• Gene: Segment of DNA coding for a protein.

• Genetic Code: Sequence of three DNA bases (codon) codes for one amino acid.

• Mutations: Changes in DNA sequence; can affect protein function.

• Epigenetics: Environmental factors and behaviors can cause changes in gene expression without altering DNA sequence.

Histology

Overview

Histology is the study of tissues and how they are arranged to form organs. Tissues are groups of similar cells performing a common function.

Primary Tissue Classes

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

• Connective tissue: Supports, binds, and protects organs.

• Muscle tissue: Responsible for movement.

• Nervous tissue: Receives and transmits signals.

Epithelial Tissue Functions

• Protection: Shields underlying tissues.

• Secretion: Produces and releases substances (e.g., mucus, hormones).

• Excretion: Eliminates waste (e.g., CO2 from lungs).

• Absorption: Takes in nutrients and other substances.

• Filtration: Selectively allows substances to pass.

• Sensation: Detects changes in environment.

Connective Tissue Functions

• Binding: Connects organs and tissues.

• Support: Provides structural framework.

• Protection: Physical and immune defense.

• Movement: Enables motion via bones and muscles.

• Storage: Stores energy (fat), minerals (bone).

• Transport: Blood transports nutrients, gases, and wastes.

Connective Tissue Components

• Protein fibers: Collagen (strength), reticular (support), elastic (flexibility).

• Ground substance: Fills spaces between cells and fibers.

Endocrine System

Hormones and Endocrine Glands

The endocrine system consists of glands that secrete hormones into the bloodstream to regulate body functions.

• Hormones: Chemical messengers that affect target cells/organs.

• Endocrine glands: Pituitary, pineal, thyroid, parathyroid, adrenal, pancreas, gonads.

• Hormone structure: Steroids (from cholesterol), peptides (chains of amino acids), monoamines (derived from amino acids).

Hormone Receptors and Effects

• Hormones bind to specific receptors on target cells to trigger physiological changes.

• Second messenger systems (e.g., cAMP) amplify hormone signals inside cells.

• Some hormones act directly on DNA to regulate gene expression.

Types of Hormone Action

• Synergistic: Multiple hormones produce a greater effect together.

• Permissive: One hormone enables another to act.

• Antagonistic: Hormones have opposing effects.

Major Endocrine Glands and Functions

• Pituitary gland: Master gland; controls other endocrine glands.

• Pineal gland: Secretes melatonin; regulates sleep cycles.

• Thyroid gland: Regulates metabolism.

• Parathyroid glands: Regulate calcium levels.

• Pancreas: Regulates blood glucose (insulin and glucagon).

• Adrenal glands: Produce stress hormones (cortisol, adrenaline).

• Gonads: Produce sex hormones (estrogen, testosterone).

Endocrine Functions of Other Organs

• Kidneys, stomach, heart, and other organs also secrete hormones affecting body functions.

Table: Comparison of Tissue Types

Additional info: Some explanations and examples have been expanded for clarity and completeness. All equations are provided in LaTeX format as required.