Comprehensive Anatomy and Physiology: Cell Structure, Systems, and Chemical Foundations

Anatomy

Structure

Physiology

Function

Hierarchy of Organization

Atom → molecule → macromolecule → organelle → cell → tissue → organ → organ system → organism

Emergent Properties

New abilities appear when parts work together

Complementary Structure

Structure is shaped by what it needs to do

Major Themes of Physiology

Homeostasis, Form follows function, Gradients drive physiology, Cell‑cell communication

Characteristics of Life

Organization, Metabolism, Growth, Development, Responsiveness, Regulation (homeostasis), Reproduction, (Sometimes) Evolution

RBC Example Theme

Integration of systems; Emergent properties (oxygen delivery requires many systems)

Major Tissue Types

Epithelial, Connective, Muscle, Nervous

11 Body Systems

Integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic/immune, respiratory, digestive, urinary, reproductive

Feedback Systems

Stimulus → receptor → control center → effector → response

Negative Feedback

Reverses change (temp, glucose, BP) — most common

Positive Feedback

Amplifies change (labor, clotting)

Afferent

Sensory input arrives

Efferent

Motor output exits

Hydration shells

Water molecules surround solutes → dissolve & stabilize them

pH

Measure of H⁺ concentration; low pH = acidic, high pH = basic

Water dissociates

H₂O ⇌ H⁺ + OH⁻

Law of mass action

Reaction shifts to restore equilibrium when concentrations change

Inorganic chemistry

No carbon backbone (water, salts)

Organic chemistry

Carbon‑based molecules (carbs, lipids, proteins, nucleic acids)

Chemical Reactions

Reactants → intermediates → products

Types of chemical reactions

Synthesis, decomposition, exchange, reversible

Dehydration synthesis

Builds polymers, removes water

Hydrolysis

Breaks polymers, adds water

Carbohydrates - Monomer

Monosaccharides (glucose)

Carbohydrates - Polymer

Polysaccharides (glycogen, starch)

Carbohydrates - Bond

Glycosidic

Carbohydrates - Ratio

~1C : 2H : 1O

Carbohydrates - Storage

Stored as glycogen in liver, muscle, brain, uterus/vagina

Carbohydrates - Metabolism

Glycogenesis & gluconeogenesis in liver

Lipids - Monomers

Fatty acids + glycerol

Lipids - Polymers

Triglycerides, phospholipids

Lipids - Bonds

Ester linkages

Lipids - Types

Fatty acids, triglycerides, phospholipids, steroids, ketones

Saturated fats

Solid; animal fats (butter, cheese)

Unsaturated fats

Liquid; plants, fish, nuts

Trans fats

Hydrogenated; baked goods, margarine (worst for health)

Coronary artery disease

Plaque buildup from excess saturated/trans fats

Roles of lipids

Membranes, hormones, energy storage, signaling

Proteins - Monomer

Amino acids

Proteins - Polymer

Polypeptides

Proteins - Bond

Peptide bond

Proteins - Functions

Enzymes, transport, receptors, structure, movement, immunity

Proteins - Structure levels

Primary → secondary → tertiary → quaternary

Proteins - Shape

Determines function; denaturation destroys function

Nucleic Acids - Monomer

Nucleotides

Nucleic Acids - Polymer

DNA/RNA

Nucleic Acids - Bonds

Phosphodiester

ATP/GTP

Nucleotides; energy currency (breaking phosphate bonds releases energy)

Transcription

Occurs in nucleus

Translation

Occurs in cytosol / ribosomes / rough ER

Modern Cell Theory

Cells come from cells, smallest living unit, contain DNA, require energy

Human cells size

~10-30 micrometers → need light microscope to see whole cells

Cell Fractionation

Break cells → centrifuge → separate organelles by density

Cell Structure - Major regions

Plasma membrane, cytoplasm (organelles + cytosol), nucleus

Ribosomes

Protein synthesis

Rough ER

Proteins for export

Smooth ER

Lipids, detox

Golgi Apparatus

Modifies, sorts, ships proteins/lipids

Lysosomes

Digestion

Peroxisomes

Detox, fatty acid breakdown

Endomembrane System

Rough ER → transport vesicle → Golgi → secretory vesicle → membrane/exocytosis

Cytoskeleton - Microfilaments

Actin; movement, shape

Cytoskeleton - Intermediate filaments

Strength, structure

Cytoskeleton - Microtubules

Transport highways, mitotic spindle

Plasma Membrane - Fluidity

Influenced by temperature, cholesterol, saturation of fatty acids

Plasma Membrane - Composition

~98% lipids (mostly phospholipids), ~2% proteins (but 50% of weight)

Phospholipid

Hydrophilic head + hydrophobic tails → forms bilayer

Extracellular matrix

Collagen, proteoglycans; used in signaling

Glycocalyx

Carbohydrate coating for ID & protection

HIV example

Virus binds specific membrane receptors (CD4)

LPS (gram‑negative bacteria)

Triggers strong immune response

Cell Cycle - Mitosis

Somatic cells; diploid

Cell Cycle - Meiosis

Gametes; haploid

Interphase

G1 (growth), S (DNA replication), G2 (prep)

G0 phase

Non‑dividing (neurons, muscle cells)

Dysregulation

Uncontrolled division → tumors

Signals for division

Growth factors, nutrients

Tumor terms

Benign, malignant, metastasis, oncogenes, tumor suppressors

Cell Adhesion - Tight junctions

Seal

Cell Adhesion - Desmosomes

Strong anchoring

Cell Adhesion - Gap junctions

Communication

Passive transport

No ATP required

Simple diffusion

Nonpolar molecules (O₂, CO₂, lipids)

Facilitated diffusion

Uses channels (ions) or carriers (glucose)

Osmosis

Water movement down gradient (via aquaporins)

Factors affecting diffusion

Size, polarity, membrane thickness, temperature, gradients

Inside vs outside cell

Inside: high K⁺, proteins; Outside: high Na⁺, Ca²⁺, Cl⁻

Osmosis & tonicity - Hypotonic

Cell swells

Osmosis & tonicity - Hypertonic

Cell shrinks

Sports drinks

Electrolytes + glucose → faster absorption than water

Active transport

Requires ATP

Primary active transport

Na⁺/K⁺ pump

Secondary active transport

Uses gradients (e.g., Na⁺/glucose cotransport)

Vesicular transport

Endocytosis/exocytosis

Na⁺/K⁺ Pump Steps

1. 3 Na⁺ bind; 2. ATP phosphorylates pump; 3. Na⁺ released outside; 4. 2 K⁺ bind; 5. Pump dephosphorylates; 6. K⁺ released inside

Electrochemical gradient

Combination of electrical charge + concentration gradient

Resting membrane potential

Inside negative relative to outside

Inside vs Outside Cell (Gradients)

Inside high: K⁺, proteins, phosphate; Outside high: Na⁺, Ca²⁺, Cl⁻, glucose.