How does counter current mechanism help gaseous exchange during respiration?
Within each lamella, counter-current flow enhances diffusion by maintaining a concentration gradient of oxygen between the water (which is relatively high in oxygen) and the blood (lower in oxygen). water is deflected over the lamellae in a direction opposite the flow of blood in the capillaries.
What is countercurrent exchange mechanism?
Countercurrent exchange is a mechanism occurring in nature and mimicked in industry and engineering, in which there is a crossover of some property, usually heat or some chemical, between two flowing bodies flowing in opposite directions to each other.
What is the difference between countercurrent exchange and countercurrent multiplier?
Countercurrent multiplication is something the tubule does to create the high interstitial osmolality, and a large osmolality gradient between the renal medulla and the renal cortex. The countercurrent exchange mechanism is something the vasa recta do to maintain this gradient.
Why is countercurrent exchange respiration so effective?
Fish gills use a design called ‘countercurrent oxygen exchange’ to maximize the amount of oxygen that their blood can pick up. They achieve this by maximizing the amount of time their blood is exposed to water that has a higher oxygen level, even as the blood takes on more oxygen.
How does a countercurrent multiplier work?
The descending and ascending loop and vasa recta form a countercurrent multiplier system to increase Na+ concentration in the kidney medulla. The collecting ducts actively pump urea into the medulla, further contributing to the high osmotic environment.
What do you understand by counter-current flow of water and blood in gills?
This is the way that a fish’s gills absorb the maximum amount of oxygen from the water. Water flows in the opposite direction to the blood flow in the gills to ensure that there is always a higher concentration of oxygen in the water than the concentration of oxygen in the blood.
What is the point of the countercurrent multiplier?
Countercurrent multiplication in the kidneys is the process of using energy to generate an osmotic gradient that enables you to reabsorb water from the tubular fluid and produce concentrated urine.
What is a vasa recta?
The vasa recta, the capillary networks that supply blood to the medulla, are highly permeable to solute and water. Because transport of salt and other solutes requires oxygen and adenosine triphosphate, reduced medullary blood flow decreases salt and solute transport by nephron segments in the medulla.
Why is it called counter current mechanism?
Because the blood flow through these capillaries is very slow, any solutes that are reabsorbed into the bloodstream have time to diffuse back into the interstitial fluid, which maintains the solute concentration gradient in the medulla. This passive process is known as countercurrent exchange.
What does the Vasa recta do?
Vasa Recta Function The vasa recta, the capillary networks that supply blood to the medulla, are highly permeable to solute and water. As with the loop of Henle, the vasa recta form a parallel set of hairpin loops within the medulla (see Chapter 2).
How does countercurrent exchange increase the efficiency of diffusion?
This efficiency stems from an adaptation known as countercurrent exchange. Counter current involves blood in the capillaries flowing in the opposite direction to the flow of water flowing over them. This creates a steep diffusion gradient along the capillary and favors rapid transfer of oxygen into the blood.
What mechanism prevent food in the pharynx from entering the respiratory system?
The epiglottis (eh-pih-GLAH-tus), a small flap of tissue, covers the air-only passage when we swallow, keeping food and liquid from going into the lungs.
What is the purpose of the countercurrent multiplier?
The countercurrent multiplier or the countercurrent mechanism is used to concentrate urine in the kidneys by the nephrons of the human excretory system. Countercurrent mechanism in Henle’s loop. The nephrons involved in the formation of concentrated urine extend all the way from the cortex of the kidney to the medulla.
What is countercountercurrent multiplier system in kidney?
countercurrent multiplier system An active process occurring in the loops of Henle in the kidney, which is responsible for the production of concentrated urine in the collecting ducts of the nephrons. Sodium and chloride ions are actively pumped from the ascending limb of the loop but water is retained, since the ascending limb is impermeable…
What is the countercurrent exchange mechanism of blood?
This results in absorption of water into the blood and return of the absorbed solute to the interstitium. This is referred to as the countercurrent exchange mechanism. In the presence of ADH (secreted in response to hypovolemia and hyperosmolality in peripheral blood), water is absorbed (without NaCl) in the collecting tubule into the medulla.
What is the function of countercurrent exchange in an U-type countercurrent exchanger?
Countercurrent exchange in an U-type countercurrent exchanger may have two functions: ( 1) trapping of solutes within the system by transfer of solutes from the ascending to the descending limb and ( 2) preventing water from entering the system by short circuiting from the descending to the ascending limb.