Renal Physiology Lab Quiz 7

Kidneys

chief regulators of the internal environment of the body. They achieve this homeostasis by regulating the pH and concentration of ions and water in the various body fluids. In addition, they also provide for the elimination of the waste products of metabolism

Renal corpuscle and renal tubule

Two main structures in nephrons

Glomerulus

blood is first filtered through this tuft of capillaries in the renal corpuscle at a rate of 120 ml/min

Three major parts of the renal tubule

proximal convoluted tubule (PCT), the nephron loop (Loop of Henle), and the distal convoluted tubule (DCT)

Plasma proteins

large molecules over 70,000 MW are exculded by tubular filtrate

Toxic by-products and excess substances in kidneys

retained in the filtrate and are finally excreted in the urine (approximately 1 ml of urine formed per minute)

Urinalysis

can yield valuable information about the health of the kidney and of the body in general

Phenylketouria (PKU)

genetically unable to metabolize the amino acid phenylanine. If accumulated in the body, phenylalanine, commonly found in food and beverage products, is converted into phenylpyruvic acid which appears in the urine.

Effects of phenylalanine accumulation

can result in developmental delays, seizures, and intellectual impairments

Diabetes mellitus

have either an imbalance or a deficit in the amount of insulin produced by the pancreas

Ketones

fatty acid metabolites that build up when the body can’t use sugar as cellular fuel

Ketone and pH trend

when ketones increase, blood pH decreases

Indication of diabetes mellitus

glucose and ketones in urine, combined with low urine pH

Labstix Test

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

Normal urine characteristics

pH of 6 (range of 4.5-8), no or trace proteins, no glucose, no ketones, no occult blood

What causes acidic urine

a diet rich in proteins or can result from respiratory disorders, dehydration, or starvation

What causes alkaline urine

can result from a diet rich in citrus fruits and dairy, vomiting, urinary tract infections, or cystitis

Cystitis

urine decomposes in the bladder with the production of ammonia

proteinuria or albuminuria

presence of protein in the urine, is a sign that the “filters,” or glomeruli, of the kidney’s nephrons are damaged, allowing blood proteins to enter the filtrate

Glycosuria

high glucose levels in urine, indicate the body’s inability to process glucose, which leads to an accumulation of glucose in the blood that is then secreted in the urine.

Ketonuria

large amounts of ketone excretion, suggest that the body is
using fat as an energy source as opposed to glucose and can indicate either diabetes mellitus or starvation

Occult blood

blood not visible to the naked eye, found in the urine typically suggests there is structural damage within the urinary tract, UTI, kidney stones, or cancerous cells

Nephritis

a disease in which the glomeruli are damaged and plasma proteins and erythrocytes leak into the nephrons, will have blood present in their urine as well as high levels of protein

300 milliosmoles per liter

kidney regulates osmolarity of body fluids at around this level

Dehydrated

kidneys produce a small amount of highly concentrated urine

Overhydrated

kidneys produce large amount of minimally concentrated urine

Specific Gravity

The ratio of the density of a substance compared to the density of distilled water

Temperature urinometer reads urine at

15C

Specific gravity value correction

add 0.001 for every 3C above, or subtrace 0.001 for every 3C below

Normal range of urine specific gravity

1.0015 to 1.035

Chronic nephritis

slow onset kidney disease, low specific gravity reading

Acute nephritis

sudden, onset kidney disease, high specific gravity

Mohr Method (NaCl concentration)

The process of titrating silver nitrate to analyze the presence of chloride
ions in a substance using potassium chromate as an indicator

Potassium chromate percentage

20%, 1 drop

Silver Nitrate percentage

2.9%, drop by drop

Each drop of silver nitrate added represents

1 g/liter of NaCl present in the urine

Group 1

800 ml water consumed

Group 2

800 ml of water and 7g NaCl consumed

Group 3

80 ml of water and 7g NaCl consumed

Trend in Group 1 urine output 0-30mins

low urine output since it takes time for ingested water to be absorbed via the digestive system

Why did Group 1 trends happen

kidneys must maintain BP during overhydration, causing excess water to be filtered out

Trend in Group 1 urine output 30-60 mins

the highest urine output as blood volume will have increased, causing the kidneys to filter more and create more urine

Trend in Group 1 urine output 60-120 minutes

urine output is still high but decreasing since the kidneys have been working to remove excess water

Specific Gravity trends among 3 groups

group 3 had the highest specific gravity at 90 minutes since it consumes the least amount of water with the most salt, resulting in more solute in the urine

NaCl concentration trends among 3 groups

group 1 had the lowest NaCl concentration at 120 minutes since they just consumed water, so the kidneys didn’t have to excrete excess solutes like groups 2 and 3