Which of the following is not a function of the integral membrane proteins?

A. Capillary network: Capillaries are microscopic vessels composed of a single layer of endothelial cells resting on a basement membrane. This extremely thin wall permits diffusion, filtration, and osmosis, allowing efficient exchange of oxygen, carbon dioxide, nutrients, and metabolic wastes between blood and surrounding tissues. Their extensive branching greatly increases surface area, making them the primary site of tissue–blood exchange.

B. The lymphatic network is a system of vessels that runs parallel to the blood capillary network and is closely associated with it. Lymphatic capillaries are blind-ended, thin-walled vessels that collect interstitial fluid, proteins, and waste from tissues that are not reabsorbed by blood capillaries. They merge into larger lymphatic vessels, eventually draining into the venous system.

C. Arteriole: Arterioles regulate blood flow into capillary beds through smooth muscle contraction and relaxation. Their relatively thick muscular walls limit diffusion, and their primary function is resistance and pressure control, not exchange.

D. End arterioles are the terminal branches of arteries that deliver blood directly to the capillary networks in tissues. They are small-diameter vessels that regulate blood flow into specific capillary beds through precapillary sphincters. End arterioles play a key role in controlling tissue perfusion, oxygen delivery, and nutrient exchange, thermoregulation and local blood pressure regulation.

E. Intercellular Cleft/Pore: These are the physical gaps between adjacent endothelial cells that allow for the paracellular passage of water and small water-soluble solutes. While they are essential mechanisms for exchange, they are a structural feature of the capillary wall rather than the functional region itself where the exchange process is collectively localized.

A. leukocytosis: Leukocytosis refers to an increase in the number of white blood cells, most commonly seen with infection, inflammation, or stress responses.

B. leukopenia: Leukopenia is defined as a decrease in the total white blood cell count, which may result from bone marrow suppression, chemotherapy, viral infections, or certain autoimmune conditions.

C. differential white blood cell count: A differential white blood cell count measures the percentage of each type of white blood cell present in the blood, rather than the total number.

D. hemostasis: Hemostasis refers to the process of blood clot formation to stop bleeding and is unrelated to white blood cell levels.