Lab Practical 2 Study Guide

What is a substrate?

The molecule an enzyme acts on.

What is an enzyme?

A protein that speeds up a chemical reaction without being used up.

What are products?

The molecules formed after an enzyme breaks down its substrate.

What substrate does amylase digest?

Starch.

What are the products of amylase digestion?

Maltose (and eventually simple sugars).

Where does amylase work?

Mouth and small intestine.

What substrate does pepsin digest?

Proteins.

What are the products of pepsin digestion?

Peptides.

Where does pepsin work?

Stomach.

What pH does pepsin require?

Acidic (around pH 2).

What substrate does lipase digest?

Triglycerides (fats).

What are the products of lipase digestion?

Fatty acids and glycerol.

Where does lipase work?

Small intestine.

What does Lugol's iodine test for?

Starch.

What color is a positive Lugol's test?

Blue-black.

What color is a negative Lugol's test?

Yellow-brown.

What does Benedict's solution test for?

Reducing sugars (glucose and maltose).

What must be done for Benedict's test to work?

The sample must be heated.

What colors indicate a positive Benedict's test?

Green, yellow, orange, or brick red depending on sugar concentration.

What does Biuret reagent test for?

Proteins.

What color is a positive Biuret test?

Purple or violet.

What color is a negative Biuret test?

Blue.

What does Phenol Red indicate?

pH changes.

What color is Phenol Red in acidic conditions?

Yellow.

What color is Phenol Red in neutral/basic conditions?

Red or pink.

Why is Phenol Red used in the lipase experiment?

Fatty acids lower the pH as fats are digested.

What are the four main functions of the nephron?

Filtration, reabsorption, secretion, and excretion.

Where does filtration occur?

Glomerulus.

What is the function of the glomerulus?

Filters blood to produce filtrate.

What stays in the blood during filtration?

Blood cells and most proteins.

What enters the filtrate during filtration?

Water, glucose, salts, amino acids, and wastes.

What is the function of Bowman's capsule?

Collects filtrate from the glomerulus.

Where does most reabsorption occur?

Proximal convoluted tubule (PCT).

What is reabsorbed in the PCT?

Water, glucose, amino acids, sodium, and vitamins.

What is secreted into the PCT?

Drugs and hydrogen ions.

What happens in the descending limb of the Loop of Henle?

Water is reabsorbed.

What happens in the ascending limb of the Loop of Henle?

Sodium, potassium, and chloride are reabsorbed.

Is the ascending limb permeable to water?

No.

What is the function of the Loop of Henle?

Creates the concentration gradient for urine concentration.

What hormone acts on the distal convoluted tubule?

Aldosterone.

What does aldosterone cause in the DCT?

Increases sodium reabsorption and potassium secretion.

What is secreted in the DCT?

Potassium and hydrogen ions.

What is the function of the collecting duct?

Final urine concentration and water reabsorption.

Which hormones act on the collecting duct?

ADH and aldosterone.

Where does aldosterone act?

Distal convoluted tubule and collecting duct.

What does aldosterone do?

Increases sodium reabsorption, water reabsorption, blood volume, and blood pressure while increasing potassium secretion.

Where does ADH act?

Collecting duct.

What does ADH do?

Increases water reabsorption and produces concentrated urine.

What happens when ADH is absent?

Large amounts of dilute urine are produced.

What does RAAS stand for?

Renin-Angiotensin-Aldosterone System.

What triggers the RAAS?

Low blood pressure or low blood volume.

Which organ releases renin?

The kidneys.

What does renin convert?

Angiotensinogen into angiotensin I.

What enzyme converts angiotensin I into angiotensin II?

Angiotensin-converting enzyme (ACE).

What are the effects of angiotensin II?

Vasoconstriction and stimulation of aldosterone release.

What is the overall goal of the RAAS?

Increase blood pressure and blood volume.

What is the normal urine result for glucose?

Negative.

What does glucose in the urine indicate?

Diabetes mellitus or high blood glucose.

What is the normal urine result for ketones?

Negative.

What do ketones in the urine indicate?

Fat breakdown due to starvation, low-carb diet, or diabetes.

What is the normal urine result for protein?

Negative or trace.

What does protein in the urine indicate?

Kidney damage, glomerular disease, hypertension

What is the normal urine result for leukocytes?

Negative.

What do leukocytes in the urine indicate?

Urinary tract infection or inflammation.

What does specific gravity measure?

Urine concentration.

What is the normal range for urine specific gravity?

1.005–1.030.

What does high urine specific gravity indicate?

Dehydration or concentrated urine.

What does low urine specific gravity indicate?

Overhydration or dilute urine.

What is the normal urine result for blood?

Negative.

What can blood in the urine indicate?

Kidney stones, UTI, trauma, menstruation contamination, or kidney disease.

Which nephron structure performs filtration?

Glomerulus.

Which nephron structure performs the most reabsorption?

Proximal convoluted tubule (PCT).

Which nephron structure is associated with ADH?

Collecting duct.

Which nephron structure is associated with aldosterone?

Distal convoluted tubule and collecting duct.

Easy memory: Amylase

Amylase digests starch.

Easy memory: Pepsin

Pepsin digests protein.

Easy memory: Lipase

Lipase digests lipids (fats).

Easy memory: ADH

ADH saves water.

Easy memory: Aldosterone

Aldosterone saves salt; water follows salt.

Easy memory: Glomerulus

Filtration.

Easy memory: PCT

Major reabsorption.

Easy memory: Loop of Henle

Water goes down, salt goes up.

Easy memory: RAAS

Raises blood pressure.

Easy memory: Leukocytes in urine

Think UTI.

Easy memory: Protein in urine

Think kidney damage.

Easy memory: Glucose in urine

Think diabetes.

Easy memory: Ketones in urine

Think fat breakdown.

Easy memory: High specific gravity

Think dehydration.