What happens to blood flow when viscosity increases?

Turgor Pressure: This is a plant biology term. It refers to the force of the cell contents pushing against the cell wall in plants, keeping them upright and rigid. It doesn't apply to human blood plasma.

Hydrostatic Pressure: It is the pressure exerted by the blood (mostly water) against the vessel walls, driven by the heart's pumping action. It pushes fluid out of the capillaries.

Oncotic pressure: The type of osmotic pressure generated by plasma proteins in the blood is oncotic pressure, also known as colloid osmotic pressure. Oncotic pressure is primarily created by large plasma proteins, especially albumin, that remain within the intravascular space. Because these proteins cannot easily cross the capillary membrane, they exert an osmotic pulling force that draws water from the interstitial space back into the bloodstream. This force helps maintain adequate circulating blood volume and counterbalances hydrostatic pressure, which pushes fluid out of the capillaries. Proper balance between hydrostatic and oncotic pressures is essential for preventing edema and maintaining normal fluid distribution between vascular and interstitial compartments.

Atmospheric Pressure: This is the weight of the air in the Earth's atmosphere. While it affects us overall, it is not a specific force generated by proteins within the circulatory system.

A. Lymphatic pressure: Lymphatic pressure contributes to the return of interstitial fluid to the circulation but does not drive the primary movement of fluid between capillaries and tissues. Lymph flow is a secondary mechanism that helps maintain fluid balance after capillary exchange.

B. Osmotic pressure: Osmotic pressure, primarily from plasma proteins like albumin, draws water into the capillaries from the interstitial space. While important for reabsorption, it opposes hydrostatic pressure rather than being the primary force driving fluid out of capillaries.

C. Hydrostatic pressure: Hydrostatic pressure is the main force pushing fluid out of capillaries into the surrounding tissue. Generated by the pressure of blood against capillary walls, it drives filtration at the arterial end of capillaries and is the dominant factor in capillary-tissue fluid exchange.

D. Blood pressure: Blood pressure reflects systemic arterial pressure but is not the direct local force responsible for fluid movement at the capillary level. Hydrostatic pressure within individual capillaries is the specific driving force controlling tissue perfusion and filtration.