Question

1. Reabsorption occurs when

a. Filtered solute is transported from the lumen of the renal tubule to the blood of the peritubular capillaries

b. Solute is transported from the blood of the peritubular capillaries to the lumen of the distal convoluted tubule

c. A protein is transported across the glomerular filtration membrane

d. Filtered solute is transported from the glomerular capillaries to the capsular space of the renal corpuscle

e. Solute that has not been filtered is excreted

2.Why is urine (filtrate) buffered?

a. To prevent abnormal increases respiratory rate

b. This increases bicarbonate production

c. To maintain a higher pH which is necessary to continue to drive H+ secretion

d. To prevent secretion of too much acid

e. Buffering filtrate is necessary for reabsorption of Na+

3. Water loss from the body will cause

a. Nothing as water loss does not determine solute loss.

b. Further water secretion to the renal tubule

c. Solute loss, like Na+

d. Secretion of solute like K+ to the renal tubule

e. Bicarbonate production by tubular epithelial cells

4. Water that diffuses out of the plasma and into the tissue to become interstitial fluid will re-enter blood circulation by way of

a. The creation of a hydrostatic pressure gradient

b. Active diffusion using transporters back into the capillary blood

c. Co-transport with sodium

d. Lymphatic vessels that transport fluid to veins

e. Osmosis back into large veins

5. The primary function of antidiuretic hormone is to

a. it delay urination.

b. it increase digestive absorption.

c. decrease the amount of water lost at the kidneys.

d. increase the amount of sodium lost at the kidneys.

e. decrease blood pressure.

Answer 1

1. a. Filtered solute is transported from the lumen of the renal tubule to the blood of the peritubular capillaries

Explanation:

The Three Steps of Urine Formation
1)Filtration,
2)Reabsorption,
3)Secretion

The kidneys filter unwanted substances from the blood and produce urine to excrete them. There are three main steps of urine formation: glomerular filtration, reabsorption, and secretion. These processes ensure that only waste and excess water are removed from the body.

1. The Glomerulus Filters Water and Other Substances from the Blood:
Each kidney possess over 1 million tiny structures called nephrons. Each nephron has a glomerulus, the site of blood filtration. The glomerulus is a network of capillaries surrounded by a cuplike structure, the glomerular capsule (or Bowman’s capsule). As blood flows through the glomerulus, blood pressure pushes water and solutes from the capillaries into the capsule through a filtration membrane. This glomerular filtration begins the urine formation process.

2. The Filtration Membrane Keeps Blood Cells and Large Proteins in the Bloodstream:
Inside the glomerulus, blood pressure pushes fluid from capillaries into the glomerular capsule through a specialized layer of cells. This layer, the filtration membrane, allows water and small solutes to pass but blocks blood cells and large proteins. Those components remain in the bloodstream. The filtrate (the fluid that has passed through the membrane) flows from the glomerular capsule further into the nephron.

3. Reabsorption Moves Nutrients and Water Back into the Blood:
The glomerulus filters water and small solutes out of the bloodstream. The resulting filtrate contains waste, but also other substances the body needs: essential ions, glucose, amino acids, and smaller proteins. When the filtrate exits the glomerulus, it flows into a duct in the nephron called the renal tubule. As it moves, the needed substances and some water are reabsorbed through the tube wall into adjacent capillaries. This reabsorption of vital nutrients from the filtrate is the second step in urine creation.

4. Waste Ions and Hydrogen Ions Secreted from the Blood Complete the Formation of Urine:
The filtrate absorbed in the glomerulus flows through the renal tubule, where nutrients and water are reabsorbed into capillaries. At the same time, waste ions and hydrogen ions pass from the capillaries into the renal tubule. This process is called secretion. The secreted ions combine with the remaining filtrate and become urine. The urine flows out of the nephron tubule into a collecting duct. It passes out of the kidney through the renal pelvis, into the ureter, and down to the bladder.

2.c. To maintain a higher pH which is necessary to continue to drive H+ secretion

3. a. Nothing as water loss does not determine solute loss.

Explanation: Water loss is independent of solute loss i.e it does not accompanies loss of solute with it.

4. a. The creation of a hydrostatic pressure gradient

5. c. decrease the amount of water lost at the kidneys

Explanation: antidiuretic hormone cause absorption of water from the kidney and prevent the water loss through the urine