Cells
🧠 Cells, Organ Systems & Digestion
1️⃣ Cells — The Building Blocks of Life
Cells are the smallest functional units of the human body.
→ Functions: structure, nutrient absorption, energy production, waste removal, communication, and replication.Made of ~70% water, plus macronutrients (protein, fat, carbohydrate) and minerals.
Contain organelles that perform specialized metabolic tasks.
⚙️ Major Organelles & Functions
Organelle Function Nucleus Stores DNA, controls cell activity Nucleolus Produces ribosomes Mitochondria Generates ATP (energy)Ribosome Builds proteins Rough ER Synthesizes proteins Smooth ER Makes lipids, hormones; detoxifies Golgi Apparatus Packages proteins for transport Lysosome Breaks down waste Peroxisome Detoxifies and breaks down fats Centriole Aids in cell division
🔬 Cell Membrane (Lipid Bilayer)
Made of 60% protein / 40% phospholipids
Controls entry/exit of substances
Polar hydrophilic heads face water, hydrophobic tails repel it → forms bilayer barrier
Allows cell signaling, nutrient transport, and communication
2️⃣ Types of Cells
The human body has 200+ specialized cell types, each suited to its role.
Category Example Function Stem Cell Blastocyst Can become any cell type Red Blood Cell Erythrocyte Carries oxygen White Blood Cell Lymphocyte Immune defense Platelet Megakaryocyte Blood clotting Nerve Cell Neuron Sends impulses Muscle Cell Myocyte Movement (voluntary/involuntary)Bone Cell Osteoblast / Osteoclast Build & remodel bone Skin Cell Keratinocyte, Melanocyte Protection & pigment Epithelial Cell GI tract lining Absorption/secretion Adipose Cell Adipocyte Stores energy (fat)Sex Cell Sperm / Ovum Reproduction
3️⃣ Tissues of the Human Body
Groups of similar cells forming functional layers.
🧩 Four Primary Tissue Types
Type Function Example Epithelial Lines & protects; secretes & absorbs Skin, GI tract, glands Connective Binds, supports, stores Bone, cartilage, fat, blood Muscle Contracts for movement Skeletal, cardiac, smooth Nervous Communication & control Brain, spinal cord, nerves
⚡ Note: Transitional epithelium (bladder) stretches; glandular epithelium secretes hormones & fluids.
4️⃣ Human Organ Systems (11 Total)
The systems are interconnected — failure in one affects the others.
SystemMain FunctionMajor ComponentsIntegumentaryProtects, regulates tempSkin, hair, nailsMuscularMovement, posture, heatSkeletal, smooth, cardiac muscleSkeletalSupport, protection, blood cell productionBones, ligaments, cartilageNervousControls body & sensesBrain, spinal cord, nervesEndocrineHormone regulationGlands (pituitary, thyroid, adrenals, pancreas)CirculatoryTransports blood, oxygen, nutrientsHeart, arteries, veins, capillariesLymphaticImmunity & fluid balanceLymph nodes, vessels, spleenRespiratoryGas exchange (O₂/CO₂)Lungs, trachea, diaphragmUrinaryExcretes waste, maintains fluid balanceKidneys, bladder, urethraReproductiveProduces offspringOvaries/testes, uterus, penisDigestiveBreaks down & absorbs nutrientsGI tract, liver, pancreas, gallbladder
5️⃣ Digestive System & Its Functions
Main Goal: Convert food → nutrients → cellular energy (ATP).
🦠 6 Core Functions
Ingestion – food enters mouth
Mechanical Digestion – chewing, stomach churning
Chemical Digestion – enzymes & acids break macronutrients
Movement – peristalsis propels food
Absorption – nutrients absorbed into blood/lymph
Elimination – wastes excreted
🧩 Digestive Tract (Alimentary Canal)
Organ Function Mouth Chews food; amylase begins starch breakdown Pharynx Passage for food, water, air Esophagus Moves food to stomach Stomach Mixes food with acid; forms chyme Small Intestine Major nutrient absorption (duodenum, jejunum, ileum)Large Intestine Absorbs water/electrolytes; forms feces Rectum/Anus Stores and eliminates waste
⚙️ Accessory Organs
OrganFunctionLiverMakes bile; detoxifies; stores glycogen & vitaminsGallbladderStores bile; aids fat digestionPancreasSecretes enzymes (amylase, lipase, protease) and hormones (insulin, glucagon)
🧪 Key Digestive Enzymes & Hormones
Enzyme/Hormone Function Amylase Breaks down starches Lipase Breaks down fats Protease/Peptidase Breaks down proteins Lactase Digests lactose Sucrase/Maltase Break sugars into glucose Gastrin Stimulates stomach acid Secretin Regulates water & pH in duodenum CCK (Cholecystokinin)Stimulates bile & pancreatic enzymes
⚖️ Takeaways
All cells and systems are interdependent — structure enables function.
Digestive health fuels every other system (circulatory, muscular, endocrine).
Encourage clients to maintain balanced nutrition + hydration to optimize cellular energy and system recovery.
Gut integrity = performance stability.
