Human Anatomy & Organ Systems
Human anatomy encompasses eleven coordinated organ systems that maintain physiological homeostasis. The circulatory system, powered by the four-chambered myogenic heart, circulates blood through pulmonary and systemic circuits; Karl Landsteiner discovered the ABO blood group system in 1900 and the Rh factor in 1940. The nervous system comprises the Central Nervous System (brain and spinal cord) and Peripheral Nervous System, utilizing neurons that transmit electrical impulses across synaptic clefts via neurotransmitters like acetylcholine and dopamine. The excretory system relies on approximately one million nephrons per kidney to filter metabolic wastes, regulating fluid balance and blood pressure through the renin-angiotensin-aldosterone system (RAAS).
Key Concepts & Examination Highlights
- Karl Landsteiner discovered the human ABO blood groups in 1900, for which he was awarded the Nobel Prize in Physiology or Medicine in 1930.
- The functional structural unit of the human kidney is the nephron, which filters blood plasma through the glomerulus and renal tubules.
- The human heart is myogenic, meaning its rhythmic contractions are initiated internally by the sinoatrial (SA) node, also known as the natural pacemaker.