ANATOMY

Detailed explanation-1: -A dense network of capillaries lies just below the skin and facilitates gas exchange between the external environment and the circulatory system. The respiratory surface must be kept moist in order for the gases to dissolve and diffuse across cell membranes.

Detailed explanation-2: -The papillary region of the dermis is composed of loose areolar connective tissue. This is named for its fingerlike projections called papillae, that extend toward the epidermis and contain terminal networks of blood capillaries.

Detailed explanation-3: -Final answer: The afferent arteriole after leaving the glomerulus forms a dense network of capillaries called secondary capillary network.

Detailed explanation-4: -The walls of capillaries are just one cell thick. Capillaries therefore allow molecules to diffuse across the capillary walls. This exchange of molecules is not possible across the walls of other types of blood vessel because the walls are too thick.

Detailed explanation-5: -The walls of the alveoli share a membrane with the capillaries. That’s how close they are. This lets oxygen and carbon dioxide diffuse, or move freely, between the respiratory system and the bloodstream.