Renal physiology

Question 1

Kidney functions (2)

Answer 1

1. Regulate pH and concentrations of ions and water in body fluids
2. Eliminate waste products of metabolism

Question 2

2 main structures of the nephron

Answer 2

1. Glomerulus

2. Renal tubule

Question 3

Glomerulus function

Answer 3

As blood passes through the kidneys it is first filtered through the glomerulus (120 ml/min), and the filtrate then passes into the renal tubule.

Question 4

Filtrate

Answer 4

The tubular filtrate is similar to blood plasma in composition except that large molecules over 70,000 MW are excluded. As this filtrate passes along the proximal and distal tubules most of the water is reabsorbed, and many essential substances are actively or passively reabsorbed back into the blood stream. Toxic by-products of metabolism and substances in excess are retained in the filtrate or are secreted into the filtrate and finally excreted in the urine

Question 5

Final composition of urine

Answer 5

The final composition of the urine is quite different from that of the glomerular filtrate and reflects the integrity of kidney function and changes in blood composition

Question 6

phenylketonuria (PKR)

Answer 6

Phenylpyruvic acid appears in the urine- results in intellectual disability

Question 7

diabetes mellitus

Answer 7

Deficient production of insulin by the pancreas results in the appearance of glucose in the urine (glycosuria). The volume of urine produced and its specific gravity give information on the state of hydration or dehydration of the body

Question 8

Normal range of urine specific gravity

Answer 8

1.0015 to 1.035. Readings above or below these limits may
indicate a pathological condition. For example, a low reading is found in chronic nephritis and a high one in
acute nephritis

Question 9

Labstix test

Answer 9

A combined test of urinary pH, protein, glucose, ketones, and occult
blood.

Question 10

Abnormally low pH along with high glucose and ketones indicates

Answer 10

Diabetes mellitus

Question 11

Alkaline urine indicates

Answer 11

Many conditions, an example being cystitis in which urine decomposes in the bladder with the production of ammonia. Urinary pH usually is slightly acid (around pH 6), but the pH may be lowered by a diet rich in proteins or citrus fruits, so pH is not very informative in itself

Question 12

Protein and occult blood in the urine indicate

Answer 12

Nephritis, a disease in which the glomeruli are damaged and plasma proteins and erythrocytes leak into the nephrons

Question 13

Osmolarity value of body fluids

Answer 13

300 milliosmoles per liter

Question 14

How did urine volume change in the group that drank pure water? Why did this happen?

Answer 14

The urine volume increases over time. At 30 minutes, the urine volume is lower because the kidneys haven’t had a lot of time to process the fluids.

Question 15

Which group had the highest specific gravity at 90 minutes and why?

Answer 15

Grou.p 3 (highest salt concentration) has the highest specific gravity because it has the highest salt content. If urine has more salt, it will be more concentrated and therefore has the highest specific gravity.

Question 16

Which group had the lowest salt concentration, and why would the value be the lowest?

Answer 16

Group 1 has the lowest salt concentration, because only water was consumed. The other groups consumed water and sodium.

Question 17

How is silver nitrate converted into g/L of salt?

Answer 17

One drop of silver nitrate represents one gram per liter of NaCl in urine