Human Anatomy and Physiology Quiz

Villus

• Finger-like projections in the small intestine
• Increase surface area for absorption of nutrients
• Covered in microvilli, further increasing surface area
• Highly permeable to nutrients due to a thin epithelial layer
• Rich capillary network to transport absorbed nutrients
• Lacteals absorb fats

Alveoli

• Tiny air sacs in the lungs
• Surrounded by capillaries with thin walls
• Facilitate efficient gas exchange
• Thin walls (one cell thick)
• Type I alveolar cells are thin for diffusion
• Type II alveolar cells secrete surfactant
• Extensive capillary network for gas transport

Proximal Convoluted Tubule

• Coiled tubular structure in the nephron
• Increases surface area for reabsorption of water, ions, and small molecules
• Highly permeable to water, ions, and small molecules
• Dense capillary network for efficient reabsorption
• Cells have many mitochondria for active transport of materials

Malpighian Body (Kidney)

• Part of the nephron involved in filtering blood and initiating urine formation
• Glomerulus: high blood flow through the glomerulus for filtration
• Bowman’s capsule: Podocytes and slit diaphragms prevent protein loss

Surface Area

• Structures with a large surface area are more efficient at carrying out their functions
• Villi and microvilli in the intestine increase surface area for nutrient absorption
• Alveoli in the lungs increase surface area for gas exchange
• The convoluted tubules in the nephron increase surface area for reabsorption

Permeability

• Structures with high permeability allow for the easy passage of substances
• Villi are highly permeable to nutrients
• Alveoli walls are thin and permeable to gases
• The proximal convoluted tubule is permeable to water, ions, and small molecules

Capillary Networks

• Capillary networks facilitate the exchange of substances between blood and tissues
• Villi have rich capillary networks to transport absorbed nutrients
• Alveoli are surrounded by extensive capillary networks for gas exchange
• The proximal convoluted tubule has a dense capillary network for reabsorption
• The glomerulus has high blood flow for filtration