Connection 1: Body Fluids → Transport in Plants (Chapter: Mineral Nutrition/Transport)

• Both use bulk flow + diffusion for transport
• Xylem in plants: carries water UP (like veins carry blood UP against gravity); both use pressure differentials
• Phloem: uses active loading (unlike passive filling in heart chambers)
• Key difference: plant system is open (xylem) and pressure-flow (phloem); animal system is closed with a pump

Connection 2: Blood Clotting → Immune System (Chapter: Human Health & Disease)

• Fibrinogen (plasma protein) → clotting; Globulins (plasma proteins) → immunity
• B-lymphocytes produce antibodies (immunoglobulins) — same family as globulins
• Complement system (part of innate immunity) interacts with clotting cascade
• Mast cells (tissue equivalent of basophils) release histamine in both allergic and healing responses

Connection 3: Cardiac Physiology → Neural Control (Chapter: Neural Control & Coordination)

• Sympathetic nervous system: increases HR + contractility (fight or flight)
• Parasympathetic (vagus nerve, CN X): slows HR, decreases contractility (rest and digest)
• This is why stress and anxiety increase heart rate (sympathetic dominance)
• Baroreceptors in carotid sinus and aortic arch signal brain for BP regulation

Connection 4: Erythroblastosis Fetalis → Genetics (Chapter: Principles of Inheritance)

• Rh factor inheritance: D allele is dominant (Rh+); dd = Rh-negative
• If father is Rh+ (DD or Dd) and mother is Rh- (dd), foetus has 50-100% chance of being Rh+
• Connects blood group genetics (IA, IB, i alleles — codominance for A and B; A and B dominant over O)

Connection 5: Haemoglobin → Breathing and Gas Exchange (Chapter: Breathing & Exchange of Gases)

• Oxyhaemoglobin formation in lungs (high p$O_{2}$); dissociation in tissues (low p$O_{2}$)
• Bohr effect: decreased pH (increased C$O_{2}$/lactic acid) reduces Hb affinity for $O_{2}$ → more $O_{2}$ released in active tissues
• C$O_{2}$ transport: 70% as bicarbonate in plasma; 23% as carbaminohaemoglobin; 7% dissolved

Connection 6: Blood Pressure → Excretory System (Chapter: Excretion)

• Kidney filtration depends on glomerular blood pressure (high hydrostatic pressure drives filtration)
• Blood pressure regulation involves kidneys (RAAS: Renin → Angiotensin I → Angiotensin II → Aldosterone → Na+ retention → water retention → ↑BP)
• Hypertension damages glomerular capillaries → chronic kidney disease (bidirectional damage)