lecture 7: digestive system

Digestive System Components

Digestive System Components

Includes mouth, pharynx, esophagus, stomach, small intestine, large intestine, and accessory organs like salivary glands, pancreas, liver, gall bladder.

Digestion Processes

Involves ingestion, secretion of digestive juices, mixing and propulsion, digestion (mechanical and chemical), absorption, and elimination.

Gastrointestinal Tract (GIT) Layers

Consists of mucosa, submucosa, muscularis, and serosa (peritoneum) with specific functions and structures.

Ascites

Accumulation of fluid in the peritoneal cavity, caused by various conditions like liver cirrhosis or malignancies.

Greater Omentum

A peritoneal fold that stores fat, contains lymph nodes, and acts as a defense mechanism against infections in the GIT.

GALT

Gut-Associated Lymphoid Tissue, a collection of immune cells found in the gastrointestinal tract.

Peristalsis

Involuntary muscle contractions that propel food along the digestive tract.

Enteric

Refers to the enteric nervous system, which controls gut functions independently but is regulated by the autonomic nervous system.

Mesenteric Arteries

Arterial blood supply to the intestines, returning nutrient-rich blood via the portal system or iliac veins.

Saliva Composition

Contains water, mineral salts, enzymes, mucus, immunoglobulins, and blood clotting factors, aiding in digestion and oral health.

Protease enzymes

Enzymes involved in protein digestion, including trypsin, chymotrypsin, ribonuclease, and deoxyribonuclease.

Pancreatic lipase

Enzyme responsible for lipid/fat digestion.

Pancreatic amylase

Enzyme that breaks down starches into sugars.

Insulin and glucagon

Hormones involved in regulating blood sugar levels.

Somatostatin

Growth-hormone-inhibiting hormone secreted by the pancreas.

Villi

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

Brush border enzymes

Enzymes attached to the intestinal lining for digestion, including maltase, sucrase, and lactase.

Cholecystokinin (CCK)

Peptide hormone that stimulates pancreatic enzyme secretion and bile production.

Small intestine functions

Includes digestion, absorption of nutrients and water, hunger/satiety regulation, and immunity.

Intrinsic factor

Substance needed for vitamin B12 absorption, produced by the stomach.

Dietary Lipids

Predominant dietary lipid composed of glycerol and three fatty acid chains, which can be saturated or unsaturated.

Phospholipids

Lipids composed of two fatty acid tails and a phosphate head, digested to free fatty acids and absorbed.

Cholesterol

Steroid found in animal foods, essential for cell membrane integrity, vitamin D synthesis, and sex hormone synthesis.

Proteins

Long molecules of amino acids making up 15% of total body mass, crucial for immunity, structural support, and various functions.

Enzymes

Biological catalysts, usually proteins, that speed up chemical reactions, highly specific and not consumed in reactions.