Digestive System Functions Overview

The passageway for food from the oral cavity to the anus; it mechanically and chemically processes food for absorption.

Organs that produce secretions aiding digestion but are not part of the digestive tract, such as the pancreas, liver and Salivary glands.

Ingestion, sensory analysis of food, lubrication, mechanical digestion (teeth, tongue), carbohydrate digestion (amylase), and lipid digestion (lipase).

Metabolic regulation (blood glucose, ammonia), haematological regulation (plasma protein synthesis), and processing of toxins and nutrients.

The network of blood vessels conveying blood from the digestive tract to the liver for processing.

Physical breakdown of food, like chewing and churning.

Blood from the intestines flows to the liver through the hepatic portal system.

Outer layer of the digestive tract that covers the muscles external, mostly

Bile salts break down lipid droplets, increasing the surface area for lipase digestion.

Stores and concentrates bile before release into the small intestine.

Folds in the stomach wall that allow expansion during meals.

Secrete HCl (stomach acid) and intrinsic factor for vitamin B12 absorption.

Produce pepsinogen, which becomes pepsin to digest proteins.

Contains bicarbonate for neutralizing stomach acid and digestive enzymes (lipase, amylase, proteases).

Pancreatic proteases are initially produced in inactive forms (e.g., trypsinogen, proelastase) to prevent digestion of the pancreas itself.

Viscous, acidic mixture of partially digested food formed in the stomach.

Absorbs nutrients from digested food, with a large surface area due to its length, circular folds, villi, and microvilli.

First part of small intestine, neutralising stomach acid and receiving chyme and digestive secretions from pancreas and liver.

Middle part of small intestine, primary site for chemical digestion and nutrient absorption.

Last part of small intestine, controls flow of digested food to colon through ileocecal valve.

Compacts and stores fecal material, absorbs water and electrolytes, produces vitamins.

Expandable pouch that receives chyme from the ileum and starts compaction of feces.

Ascending, transverse, descending, and sigmoid colon; largest section of large intestine responsible for reabsorbing water and electrolytes to compact the waste.

Physical breakdown of food, not always necessary after initial digestion.

The process of chewing food using teeth and tongue to break down large pieces into smaller ones for easier swallowing.

The palate, the roof of your mouth, allows you to breathe through your nose while chewing food.

Wave-like muscle contractions that push food through your digestive tract.

The stomach churns and mixes food with gastric juices to start digestion.

Partially digested food that is mixed with gastric juices in the stomach. It resembles a thick porridge.

The small intestine mixes chyme with digestive juices for further digestion and absorption of nutrients.

A type of muscle contraction in the small intestine that mixes chyme with digestive juices.

It mixes chyme with digestive juices and bile, turns food into chyme, and increases contact between chyme and intestinal walls for absorption and digestion.

Fat digestion begins in the mouth with the enzyme lingual lipase.

An enzyme secreted by the tongue that starts the breakdown of fats in the mouth.

The acidic environment of the stomach inactivates lingual lipase due to its limited pH range.

The primary enzyme responsible for fat digestion, secreted by the pancreas and active in the small intestine.

Bile emulsifies fat, breaking large fat droplets into smaller ones, increasing surface area for pancreatic lipase to act.

Bile increases the surface area of fat for pancreatic lipase to work on, which leads to more efficient fat breakdown.

The small intestine provides the ideal environment with pancreatic lipase and bile, allowing for efficient fat breakdown.

Unlike carbohydrates and proteins, fat digestion has only one major conversion step, from triglycerides to monoglycerides and fatty acids.

Worn-out cells break down into amino acids, which are then reused to build new proteins.

The liver can convert amino acids into fatty acids or glucose, depending on the body's needs.

During starvation, the body breaks down muscle protein into amino acids, which are then used to produce glucose for energy.

Amino acids are broken down into metabolic intermediates like pyruvate and acetyl-CoA, which fuel energy production through the Krebs cycle.

Protein catabolism (breakdown) produces toxic ammonium ions, which are converted to urea in the liver for safe elimination.

Protein synthesis (creating new proteins) is essential for growth and repair. It involves linking amino acids together, requiring energy and direction from DNA and RNA.

The thyroid gland produces thyroid hormone, which influences metabolic rate by increasing ATP production and affecting genes.

Hormones like glucagon, cortisol, and adrenaline regulate metabolic processes, primarily by controlling blood glucose levels through glycogen breakdown, glucose synthesis, and fat breakdown.