Organ Systems - Complete Interactive Lesson
Part 1: Cardiovascular System
🏥 Organ Systems
Part 1 of 7 — Cardiovascular System
Heart: 4 chambers; right side pumps to lungs (pulmonary), left side pumps to body (systemic).
Cardiac cycle: SA node pacemaker, atrial contraction, AV node delay, ventricular contraction.
Concept Check 🎯
Key Insight: Blood pressure: systolic/diastolic; regulated by baroreceptors, RAAS, and ANP.
MCAT Tip: Blood components: RBCs (O2 transport), WBCs (immunity), platelets (clotting), plasma (fluid).
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Part 2: Respiratory System
Respiratory System
Part 2 of 7 — Respiratory System
Ventilation: diaphragm contracts (inhalation), relaxes (exhalation); negative pressure breathing.
Gas exchange: O2 diffuses into blood in alveoli; CO2 diffuses out — driven by partial pressure gradients.
Concept Check 🎯
Key Insight: Hemoglobin: cooperative binding, sigmoid curve; Bohr effect: low pH/high CO2 shifts curve right (releases O2).
MCAT Tip: Lung volumes: tidal volume, vital capacity, residual volume, total lung capacity.
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Part 3: Renal & Excretory System
Renal & Excretory System
Part 3 of 7 — Renal & Excretory System
Nephron: glomerulus (filtration), PCT (reabsorption), loop of Henle (concentration), DCT/CD (fine-tuning).
GFR = glomerular filtration rate; filtered = all small molecules, not proteins/cells.
Concept Check 🎯
Key Insight: ADH (from posterior pituitary): increases water reabsorption in collecting duct.
MCAT Tip: Aldosterone: increases Na+ reabsorption (and thus water) in DCT; RAAS regulates blood pressure.
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Part 4: Digestive System
Digestive System
Part 4 of 7 — Digestive System
Mechanical digestion (mouth, stomach) + chemical digestion (enzymes, bile).
Stomach: HCl activates pepsinogen to pepsin (protein digestion), pH ~2.
Concept Check 🎯
Key Insight: Small intestine: pancreatic enzymes (trypsin, lipase, amylase) + bile salts emulsify fats.
MCAT Tip: Absorption: amino acids and sugars via villi in small intestine; water absorbed in large intestine.
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Part 5: Endocrine System
Endocrine System
Part 5 of 7 — Endocrine System
Hypothalamus controls pituitary; anterior pituitary releases FSH, LH, TSH, ACTH, GH, prolactin.
Thyroid: T3/T4 increase metabolic rate; Parathyroid: PTH increases blood Ca2+.
Concept Check 🎯
Key Insight: Adrenal cortex: cortisol (stress), aldosterone (Na+ retention); Adrenal medulla: epinephrine.
MCAT Tip: Pancreas: insulin (lowers glucose, promotes storage) vs glucagon (raises glucose, promotes breakdown).
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Part 6: Nervous System
Nervous System
Part 6 of 7 — Nervous System
Central nervous system: brain + spinal cord; Peripheral: somatic + autonomic.
Autonomic: sympathetic (fight or flight) vs parasympathetic (rest and digest).
Concept Check 🎯
Key Insight: Neuron: dendrites receive, axon transmits, synaptic terminal releases neurotransmitters.
MCAT Tip: Action potential: resting (-70mV), depolarization (Na+ in), repolarization (K+ out), refractory period.
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Part 7: Review & MCAT Practice
Review & MCAT Practice
Part 7 of 7 — Review & MCAT Practice
Central nervous system: brain + spinal cord; Peripheral: somatic + autonomic.
Autonomic: sympathetic (fight or flight) vs parasympathetic (rest and digest).
Concept Check 🎯
Key Insight: Neuron: dendrites receive, axon transmits, synaptic terminal releases neurotransmitters.
MCAT Tip: Action potential: resting (-70mV), depolarization (Na+ in), repolarization (K+ out), refractory period.
Concept Check 🎯
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