Lab 3: Digestive and Urinary Anatomy and Physiology

Function of the Mouth and Esophagus in Digestion

• Mouth: mechanical breakdown chewing reduces size) and chemical breakdown (carbohydrate digestion via amylase)

  • Amylase is secreted from the salivary glands

• Esophagus: transports food to the stomach

Function of the Stomach

Mechanical and chemical processing

• Digests proteins using acids and enzymes, specifically pepsin

Function of the Small and Large Intestine

• Small: chemical processing and absorption of nutrients and water

• Large: water absorption and formation of feces

Function of the Liver

Secretes molecules required for fat digestion

• Produces bile to emulsify fats

Function of the Galballder

Stores secretions from liver (bile) and empties/releases it into the small intestine

Function of the Pancreas

Secretes enzymes and other material into the small intestine

• Specifically lipase and amylase to help digest food

Microscopic Layers of the Small Intestine (Outside → Inside)

Serosa (peritoneum) → muscularis → submucosa → mucosa

Serosa (Peritoneum)

Outer protective membrane that lines the coelom and covers digestive organs

Muscularis

Outer longitudinal and inner circular layers whose contractions mix food with digestive secretions and move the food mass by peristalsis

Submucosa

Inner epithelial lining that secretes intestinal juices and absorbs nutrients

Villi in the Mucosa

Fingerlike extensions of the mucosa that project into the lumen of the small intestine and increases surface area available for absorption

• Covered by microvilli, which are are extensions of epithelial cells in the villi

Main Function of the Kidneys

Filter waste products, toxins, and excess water from the blood to produce urine

Function of the Ureter

To transport urine from the kidneys to the bladder, where it gets stored until it is excreted

Renal Cortex

The outer region of the kidney that contains filtration structures (glomerulus and Bowman’s capsule)

Renal Medulla

The inner region of the kidney that contains renal pyramids and tubules (loop of Henle and collecting duct)

Renal Pelvis

Collects urine before it enters the ureter

• Urine drainage system (in to out): renal pyramid → minor calyx → major calyx → renal pelvis → ureter

Function of the Glomerulus and Bowman’s Capsule

Together, forms the renal corpuscle which filters blood and forms the pre-urine

Function of the Proximal Tubule

Reabsorption of ions (like Na+ and Cl-), glucose, amino acids, and water

Functions of the loop of Henle

Establishes a concentration gradient in the medulla allowing for water reabsorption later

• Descending limb is permeable to water: water leaves

• Ascending limb is impermeable to water: pumps out Na+

Function of the Distal Tubule and Collecting Duct

Water reabsorption depending on the needs/hydration level of the body

RGL of Lizards

• Herbivores tend to have longer digestive tracts/higher RGL due to the complexity of breaking down plant material

• Carnivores tend to have shorter/simpler tracts since meat is easy and quick to break down