Main Functions of Digestive System
Breaks down food, absorbs nutrients, eliminates waste, maintains immunity, secretes enzymes, supports intestinal flora.
Key functions include digestion and nutrient absorption.
Organs of the Digestive System
Mouth, pharynx, esophagus, stomach, small intestine (duodenum, jejunum, ileum), large intestine/colon, liver, pancreas, salivary glands.
Each organ plays a specific role in the digestive process.
Role of Mouth
Teeth cut and crush food; tongue mixes food with saliva to form bolus; saliva lubricates, dilutes food, contains amylase (ptyalin) to break down starch.
The mouth is the entry point for food.
Role of Pharynx
Digestive crossroads; directs bolus to esophagus and air to larynx; prevents gagging.
It connects the mouth to the esophagus and the airways.
Role of Esophagus
25 cm tube with peristalsis contractions that push bolus to stomach.
The esophagus is crucial for transporting food.
Stomach Anatomy
Located under diaphragm; has cardia (entry) and pylorus (exit sphincter); tunics: external, muscular, internal (secretes mucus and gastric juice).
The stomach is structured to facilitate digestion.
Stomach Function
Mixes food with gastric juice (pepsin + HCI), forms chyme, pushes chyme into duodenum.
Chyme is a semi-liquid mixture that moves to the small intestine.
Sections of Small Intestine
Duodenum (receives bile + pancreatic juice), jejunum, ileum (opens into colon).
Each section has specialized functions in digestion and absorption.
Function of Small Intestine
Major site of nutrient absorption; forms chyle.
Chyle is a milky fluid containing fat droplets and lymph.
Parts of Large Intestine
Cecum (with appendix), ascending, transverse, descending colon, rectum, anus.
The large intestine is involved in water reabsorption and feces storage.
Function of Large Intestine
Reabsorbs water, stores feces until defecation.
It plays a key role in waste management.
Salivary Glands
Secrete saliva (water, minerals, ptyalin) to form bolus and start starch breakdown.
Saliva is essential for initiating the digestive process.
Gastric Glands
Secrete mucus, pepsin, hormones to digest proteins and stimulate motility.
These glands are crucial for the digestive activities in the stomach.
What is the function of the pancreas?
Produces pancreatic juice (enzymes: trypsin, amylase, lipase) + hormones (insulin, glucagon)
The pancreas plays a crucial role in both digestion and blood sugar regulation.
What does the liver produce and what are its functions?
Produces bile (breaks fat into fatty acids + glycerol), stores glucose as glycogen, detoxifies blood
The liver is essential for digestion and metabolic processes.
What do intestinal glands secrete?
Secrete intestinal juice (water, mucus) for digestion
This secretion aids in the digestion and absorption of nutrients.
What are the differences between mechanical and chemical digestion?
Mechanical: mastication, peristalsis. Chemical: enzymatic breakdown of carbs, proteins, fats
Both processes are essential for effective digestion.
What is absorption in the context of the digestive system?
Nutrients pass into blood (capillaries) or lymph (lacteals); liver distributes nutrients
Absorption is critical for nutrient availability to the body.
What are the key functions of the liver?
Stores nutrients, converts amino acids to urea, maintains temperature, detoxifies, produces bile
The liver’s functions are vital for overall health and homeostasis.
What role does intestinal flora play in digestion?
Helps digestion by breaking down fibers, synthesizes vitamins (like vitamin K), supports immunity by outcompeting harmful bacteria
Intestinal flora is essential for digestive health and immune support.
How does the digestive system contribute to immunity?
Mucous membrane protects from infectious diseases; gut-associated lymphoid tissue (GALT) provides immune defense
The gut plays a significant role in the body’s immune response.
What is the endocrine function of the digestive system?
Secretes hormones (like gastrin, secretin, cholecystokinin) that regulate digestive secretions and motility
These hormones are crucial for coordinating digestive processes.
