Chemical Digestion and Disorders

Mechanical Digestion

Physical breakdown of food into smaller pieces to increase surface area without altering chemical structure.

Chemical Digestion

Breakdown of complex molecules into simpler, absorbable nutrients using enzymes and chemical agents.

Enzymes

Biological catalysts (proteins) that speed up chemical reactions without being consumed.

Amylase

Breaks down starch into maltose and glucose; produced by salivary glands and pancreas.

Protease

Breaks down proteins into peptides and amino acids; acts in stomach and small intestine.

Lipase

Breaks down lipids into fatty acids and glycerol; secreted by the pancreas into the small intestine.

Cellulase

Breaks down cellulose into cellobiose and glucose; produced by gut microbes, not mammals.

Gut Flora Functions

Includes fiber digestion, immune protection, vitamin synthesis, and metabolic regulation.

Pancreas Dual Function

Acts as an exocrine gland (digestive enzymes, bicarbonate) and endocrine gland (hormones).

Insulin

Released by pancreatic beta cells during high blood glucose to promote glucose uptake and glycogen storage.

Glucagon

Released by pancreatic alpha cells during low blood glucose to stimulate glycogen breakdown into glucose.

Bile Production and Storage

Produced by liver hepatocytes, stored/concentrated in the gallbladder, and secreted into the duodenum.

Bile Functions

Emulsifies fats to increase surface area for lipase and neutralizes acidic stomach chyme.

Liver Vitamin Storage

Stores fat-soluble vitamins (A, D, E, K) and water-soluble vitamin B12.

Nutritional Deficiency vs. Disorder

Deficiency is insufficient nutrient intake; a disorder is a physiological malfunction from improper intake or digestive issues.

Scurvy (Guinea Pigs)

Caused by Vitamin C deficiency; symptoms include lethargy, joint pain, and bleeding gums.

White Muscle Disease (Lambs)

Caused by Vitamin E and/or Selenium deficiency; causes muscle weakness and heart failure.

Milk Fever / Hypocalcemia

Severe calcium deficiency around calving; causes muscle tremors and inability to stand.

Rickets (Dogs)

Deficiency in Vitamin D, calcium, or phosphorus; causes bowed legs and bone deformities.

Anemia (Cats)

Caused by iron, B12, or folic acid deficiency or blood loss; causes pale gums and weakness.

Obesity

Caused by caloric intake exceeding expenditure; causes excess body fat and joint strain.

Goiter (Sheep)

Caused by iodine deficiency; causes an enlarged thyroid gland and low fertility.

Urolithiasis

Caused by mineral imbalance and dehydration; symptoms include straining to urinate and blood in urine.

Diabetes Mellitus

Caused by insufficient insulin or cellular resistance; symptoms include excessive thirst, urination, and weight loss.

Anorexia in Animals

Caused by disease, pain, or stress; results in total loss of appetite and rapid weight loss.

Constipation

Caused by dehydration or lack of fiber; results in infrequent, painful, dry feces.

Diarrhea

Caused by diet changes, infections, or toxins; results in frequent loose stools and dehydration.

Peristalsis

Wave-like smooth muscle contractions that push food through the gastrointestinal tract.

Villi

Finger-like projections in the small intestine that greatly increase surface area for nutrient absorption.

Enzyme Substrate Specificity

Each enzyme has a unique active site fitting only one specific substrate like a lock and key.