Course review
Review each learning objective in this topic, then open its concept explanation or question set.
Learning objective
• Capillaries are narrow, highly branched, and close to cells • One-cell-thick endothelial walls reduce diffusion distance • Fenestrations in some capillaries allow rapid exchange and tissue fluid formation
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Learning objective
• Arteries and veins have endothelium, smooth muscle, elastic tissue, and collagen • Arteries have thicker walls and smaller lumens to withstand high pressure • Veins have wider lumens and thinner walls for low-pressure return
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Learning objective
• Thick artery walls and collagen prevent rupture under high pressure • Elastic fibres stretch and recoil to even out pulse pressure and maintain flow • Smooth muscle in arteries and arterioles regulates blood distribution
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Learning objective
• Ventricular contraction creates a pressure wave felt as a pulse • Pulse rate can be measured at radial or carotid arteries • Counting for a full minute is most accurate; shorter counts can be scaled
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Learning objective
• Veins have valves that prevent backflow toward capillaries • Thin flexible walls allow surrounding muscles to compress veins • Large lumens reduce friction during low-pressure blood return
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Learning objective
• Atherosclerosis forms plaques beneath damaged coronary artery endothelium • Plaque rupture can trigger thrombosis and occlude coronary arteries • Reduced oxygen supply can kill cardiac muscle and cause myocardial infarction
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Learning objective
• Transpiration from leaf mesophyll creates tension in xylem water columns • Cohesion between water molecules transmits tension from leaves to roots • Adhesion to xylem walls helps maintain an unbroken transpiration stream
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Learning objective
• Mature xylem vessels are dead, hollow tubes with absent or perforated end walls • Lignified walls resist collapse under negative pressure and waterproof the vessel • Pits allow lateral movement of water between vessels and surrounding tissues
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Learning objective
• Dicot stems have epidermis, cortex, pith, and vascular bundles in a ring • Each vascular bundle contains xylem, phloem, cambium, and supporting fibres • Plan diagrams show tissue positions without drawing individual cells
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Learning objective
• Dicot roots have epidermis with root hairs, cortex, endodermis, and central vascular tissue • Xylem forms a central cross with phloem between its arms • The Casparian strip blocks apoplast flow and forces selective symplast entry to xylem
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Learning objective
• Hydrostatic pressure at arteriole ends forces plasma fluid out by ultrafiltration • Plasma proteins remain in blood and maintain osmotic pull • Reduced pressure near venule ends allows about 90% of tissue fluid to re-enter capillaries
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Learning objective
• Tissue fluid bathes body cells and mediates exchange with blood • Oxygen, glucose, amino acids, ions, and wastes diffuse between cells and tissue fluid • Tissue fluid has fewer proteins, less oxygen, and more carbon dioxide than blood plasma
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Learning objective
• Lymph capillaries drain excess tissue fluid that does not re-enter blood capillaries • Lymphatics use smooth muscle, body movement, and valves to move lymph • Lymph nodes filter debris and contain immune cells before lymph returns to veins
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Learning objective
• Bony fish have single circulation: heart to gills to body and back • Mammals have double circulation with separate pulmonary and systemic circuits • Double circulation keeps oxygenated and deoxygenated blood separate and maintains high systemic pressure
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Learning objective
• Four chambers and a septum separate right pulmonary and left systemic flow • Valves and tendinous cords ensure one-way blood movement • Thick left ventricular muscle, coronary arteries, and myogenic cardiac muscle support pressurized pumping
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Learning objective
• The sinoatrial node initiates excitation, followed by atrial systole • The atrioventricular node delays conduction before ventricular systole • Ventricular systole opens semilunar valves; diastole allows refilling and recovery
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Learning objective
• Endodermal cells actively pump mineral ions into xylem • This lowers xylem water potential so water enters by osmosis • Positive root pressure can push water upward when transpiration is low
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Learning objective
• Phloem sieve tube elements are living tubes with sieve plates and reduced organelles • Companion cells contain many mitochondria and connect by plasmodesmata • Active loading at sources and unloading at sinks drive pressure-flow translocation of sucrose and amino acids
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