LAB Digestive Function & Urinalysis testing

Lab 9

2 main groups of digestive organs

Gastrointestinal tract organs and accessory digestive organs & structures

Gastrointestinal tract organs

Directly associated with digestion of food. From mouth to anus including: mouth, pharynx, esophagus, stomach, small intestine and large intestine

Accessory digestive organs and structure

Assist in digestion either mechanically or chemically manipulating ingested food. Includes: lips, cheeks, palate, tongue, teeth, gums, salivary glands, gallbladder, liver, and pancreas

Mouth (key features)

• Mechanical digestion by chewing

• Salivary glands → saliva

  • Amylase → start break dong of starch

• Serous cells → back of tongue

  • Lingual lipase → fat-digesting enzyme → activates in stomach

Pharynx & Esophagus

• Propulsion of food swallowed

• No digestive enzymes

Stomach

• Holding area

• Mechanical breakdown

• Gastric pits → cells secrete factors of gastric juice

• Parietal cells

  • Hydrochloric acid (lowers pH)

    • breaks down plant cell walls

  • Intrinsic factor

• Mucus neck cells + surface epithelium → bicarbonate-rich mucus

• Chief cells → pepsinogen

  • In HCl activates → pepsin to digest protein

• Gastric lipase → digest fats

Small Intestine

• Main site of absorption

• Duodenum contains bicarbonate-rich juice to neutralize acid

• Intestinal juice → carrier fluid for nutrient absorption, slightly alkaline

• Cholecystokinin (CCK) → hormone stimulated by fatty chyme, contracts gall bladder, relaxes hepatopancreatic sphincter

• Enteropeptidase activates trypsinogen → trypsin

• Intrinsic factor binds vitamin B12

  • absorbed in ileum

Liver + Gallbladder

• Bile secreted by liver, stored in gallbladder

  • Emulsifies fats → small particles easy to digest

  • Secreted into duodenum for fatty chyme

• CCK from duodenum causes gallbladder to contract and hepatopancreatic sphincter to contract

  • bile and pancreatic juice enters duodenum

Pancreas

• Pancreatic juice → rich in enzymes

  • Many inactive until in duodenum

• Trypsinogen + enteropeptidase → trypsin

  • Activates more trypsinogen, pancreatic proteases, pro-carboxypeptidase, chymotrypsinogen into active forms.

  • Carboxypeptidase & chymotrypsin

• Amylase, sucrase, lactase, maltase, lipases and nucleases into small intestine

Large Intestine

• Some chemical digestion; enteric bacteria

  • Bacteria synthesise B complex vitamins & vitamin K

  • Metabolize undigested polysaccharides

• absorption of water, electrolytes, bacteria

• propulsion of feces + storage

• Defecation

Urinalysis

Macroscopic and microscopic examination of urine

Macroscopic analysis (5)

• Color

  • Yellow (pale to dark amber)

  • Red = blood

  • Yellow-brown or green brown = bilirubin

• Clarity

  • Cloudiness

• Specific gravity

• pH

  • around 6 (4.5 - 8)

• Odor

  • Strong odor may indicate metabolic status, pregnancy, UTI or dehydration

Microscopic analysis

• Organized sediments (cells and casts)

  • Casts = cylindrical structures from precipitation of protein and agglutination of cells within renal tubules. Indicates pathological condition

  • Cells = epithelial, erythrocytes, leukocytes = normal

• Unorganized sediments

  • Crystals

  • Small amounts normal, large amounts may indicate pathological condition

Epithelial cells in urine

• Small amounts normal (exfoliated from urinary tract)

• Large amounts = renal pathology/bacterial infection

Erythrocytes & leukocytes in urine

Pathology of urinary tract; inflammation

Types of casts in urine and significance (4)

• Hyaline

  • Most common, normal in small amts, large after exercises or dehydration

• Granular

  • 2nd most common type, breakdown of cellular casts; large amts after vigorous exercise or if chronic renal disease

• Fatty

  • From breakdown of lipid-rich epithelial; indicates high urinary protein nephrotic syndrome

• Waxy

  • Formed when urine retained due to renal pathology

Microbes in urine (3)

• Bacteria

  • Enter urethra and bladder from skin, cause UTIs

  • Untreated spread to kidneys

• Yeasts

  • More likely if vaginal yeast infection occurred

• Parasites

  • Trichomonas vaginalis in urine from contamination during vaginal infection

Struvite or Triphosphate crystals

• Common in normal urine at various pH

• Precipitates as stones in alkaline urine

• Bacterial infections promote stone formation

Cystine Crystals

• Uncommon in urine

• Indicate cystinuria = inherited metabolic disorder

• Acidic urine

• Aggregate in layers

Calcium Oxalate Crystals

• Common at various pH

• Form in stored urine

• Increased # may indicate renal failure

  • asparagus, rhubarb, garlic

  • ethylene glycol poisoning and diabetes

• Monohydrate = dumbbells

• Dihydrate = octahedral

Uric Acid Crystals

• Abnormal

• Final product of metabolism of meat, and purine-rich foods

• Increased in Type II diabetics

• Can promote calcium oxalate stones

• Elevated with gout and chronic nephritis

Hippuric Acid Crystals

• Rare

• No clinical significance

Calcium Phosphate Crystals

• Normal in low levels

• Increased # can promote stone formation

• Precipitates in alkaline urine

• Causes may be autoimmune disease affecting kidnets

  • Sjoren disease, monoclonal protein diseases and certain drugs

Calcium carbonate Crystals

• Rare, normal in alkaline urine

• May promote stone formation

• indicates large quantity of vegetables in diet

Cholesterol Crystals

• Rare

• Found in proteinuria

• May indicate Nephrotic Syndrome

Urine Bilirubin

• Uncommon

• Unconjugated form indicates hemolytic anemia or liver damage

Urine Leukocytes

• Common in urine in low #

• Indicates person has UTI if elevated

Glycosuria

Glucose present in urine; indicates high blood glucose levels. May be from excessive carbohydrate intake or diabetes mellitus uncontrolled

Albuminuria

Albumin in urine, indicates increased permeability of glomerulus to the protein

Ketonuria

Ketones in urine; Can be from low carbohydrate diet, starvation, prolonged vomiting, or dehydration. Indicates metabolic abnormalities. Coupled with glycosuria, used to confirm diagnosis of diabetes mellitus

Nitrites in urine indicate

Bacterial infections of bladder

Bilirubinuria

Elevated bile in urine, indicates liver problem (hepatitis, cirrhosis, or bile duct blockage. Yellow foam when urine shaken.

Leukocyturia

Indicated presence of white blood cells or other components of pus (pyuria) in the urine. Indicates inflammation of urinary tract. Leukocyte esterase is enzyme found in WBCs, test run to confirm presence of UTI

Red Blood Cells in urine

Not normal, indicates inflammation of kidneys, bladder or urethra. Strenuous exercise possible cause.

Hemoglobinuria

Hemoglobin in urine; indicates pathological problem: hemolytic anemia, burns, poisonous snake bites, renal diseases, and transfusion reactions.

Blood Urea Nitrogen (BUN)

• Urea is by-product of protein metabolism

• Elevated levels → kidney malfunction

• kidney disease, heart problems, diabetes

Creatinine

• Produced by muscle as metabolizes creatine

• Kidney function assessed → how well eliminates compound over 24h period

Electrolyte Panel

• Test measures: Sodium, potassium, chloride, and bicarbonate levels

• Determine if suffering from dehydration, kidney diseases, lung disease or heart condition

Exercise: Urine Physical Characteristic Observations

Pour 10ml into labeled medicine cup. Observe and record color, clarity, and smell of the urine.

Test pH of Urine

Dip pH test strip into simulated urine, compare colour to comparator chart within 30 seconds

Testing for protein (Biuret Test)

Transfer 2-3ml of urine into test tube, add 2-3ml (with pipet) of Biuret solution to urine and swirl tube; positive reaction = orange-red colour, negative = green colour

Testing for Glucose in Urine (Benedict’s Test)

Transfer 2-3ml of urine into test tube, add 2-3ml of Benedict’s solution, swirl tube and note colour. Place tube into hot water for 5 minutes; remove from heat and note colour. Red-orange precipitate at bottom of tube = positive reaction, overall green colour = negative