Lecture 1 Digestive System

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Questions and Answers

What is the primary function of the propulsion process in the digestive system?

To facilitate movement of food through the GI tract (correct)

To increase contact of food with digestive chemicals

To release digestive enzymes

To break down large nutrient molecules into smaller ones

What is the name of the process by which food is broken down into smaller molecules?

Secretion

Ingestion

Digestion (correct)

Absorption

What is the term for the movement of digested molecules into the blood and lymph?

Ingestion

Absorption (correct)

Digestion

Defecation

What is the layer of the GI tract that comes into contact with food and digesting chemicals?

Mucosa (C) Signup and view all the answers

What is the term for the process of taking food and liquids into the mouth?

Ingestion (D) Signup and view all the answers

What is the term for the elimination of wastes, undigested material, and other substances from the body?

Defecation (B) Signup and view all the answers

What is the function of the pyloric sphincter?

To regulate the passage of chyme into the duodenum (B) Signup and view all the answers

Which part of the stomach is the most superior and lies under the diaphragm?

Fundus (A) Signup and view all the answers

What is the function of intrinsic factor in the stomach?

To aid in the absorption of vitamin B12 (A) Signup and view all the answers

What is the term for the process of food particles being forced back into the body of the stomach for further mixing with gastric juices?

Retropulsion (B) Signup and view all the answers

What is the approximate volume of the stomach that serves as a reservoir?

1-1.5 L (B) Signup and view all the answers

What is the term for the passage of chyme from the stomach into the small intestine?

Gastric emptying (A) Signup and view all the answers

Where is the liver located?

In the right upper quadrant (A) Signup and view all the answers

What is the function of the bile produced by the liver?

To emulsify fats (B) Signup and view all the answers

What is the name of the lobe that is located lateral to the IVC?

Caudate lobe (D) Signup and view all the answers

What is the function of the liver in metabolism?

To store glycogen and convert it to glucose (B) Signup and view all the answers

What is the name of the small ducts between hepatocytes that collect bile?

Bile canaliculi (C) Signup and view all the answers

What is the term for the process of engulfing and digesting old red and white blood cells and some bacteria?

Phagocytosis (D) Signup and view all the answers

What is the duration of the gastric phase?

3-4 hours (D) Signup and view all the answers

What is the function of the large intestine in terms of absorption?

Absorption of vitamins and water (D) Signup and view all the answers

Which hormone is involved in the intestinal phase of digestion?

CCK and GIP (C) Signup and view all the answers

What is the structure of the muscularis in the large intestine?

Longitudinal muscle layer (B) Signup and view all the answers

What is the name of the blind pouch in the large intestine?

Cecum (B) Signup and view all the answers

What is the shape of the sigmoid colon?

S-shaped (D) Signup and view all the answers

What is the percentage of oxygenated blood supplied to the liver by the hepatic artery?

30% (C) Signup and view all the answers

Which part of the liver receives deoxygenated blood from the hepatic portal vein?

Hepatic sinusoids (C) Signup and view all the answers

What is the name of the tube that is used to relieve esophageal varices?

Sengstaken-Blakemore tube (A) Signup and view all the answers

Which enzyme is responsible for breaking down proteins in the small intestine?

Trypsin (B) Signup and view all the answers

What is the name of the hormone that stimulates the pancreas to secrete enzymes?

CCK (B) Signup and view all the answers

What is the name of the duct that is formed by the union of the right and left hepatic ducts?

Common hepatic duct (A) Signup and view all the answers

Which layer of the GI tract is in direct contact with the contents of the GI tract and is sloughed off and replaced every 5 to 7 days?

Epithelium (A) Signup and view all the answers

What is the function of the MALT in the GI tract?

To protect the body against infections (C) Signup and view all the answers

Which layer of the GI tract contains many blood and lymphatic vessels?

Lamina Propria (D) Signup and view all the answers

What is the function of the submucosal plexus in the GI tract?

To control muscular contractions of the GI tract (C) Signup and view all the answers

Which layer of the GI tract is responsible for involuntary contractions that help break down food, mix it, and propel it?

Muscularis (D) Signup and view all the answers

Which type of muscle is found in the mouth, pharynx, upper esophagus, and external anal sphincter?

Skeletal muscle (B) Signup and view all the answers

What is the function of the serosa layer in the GI tract?

To form the visceral peritoneum (A) Signup and view all the answers

What is the primary function of the peritoneal cavity?

To provide a lubricating fluid to reduce friction between the visceral and parietal peritoneum (A) Signup and view all the answers

Which structure is the largest serous membrane of the body?

Peritoneum (B) Signup and view all the answers

Which of the following structures is NOT retroperitoneal?

Transverse colon (B) Signup and view all the answers

Which of the following peritoneal folds is not retroperitoneal?

Greater Omentum (D) Signup and view all the answers

What is the primary function of the uvula?

To prevent food from entering the nasal cavity (C) Signup and view all the answers

Which of the following phases of deglutition is under voluntary control?

Voluntary phase (A) Signup and view all the answers

What is the function of the Mesentery and Mesocolon?

To hold the intestines loosely in place and allow for movement (C) Signup and view all the answers

What is the location of the esophagus in relation to the trachea?

Posterior to the trachea (C) Signup and view all the answers

What is the function of the cardiac sphincter?

To control the opening of the esophagus into the stomach (B) Signup and view all the answers

What is the shape of the stomach in most people?

J-shaped (A) Signup and view all the answers

What is the function of the soft palate?

To form the roof of the mouth (C) Signup and view all the answers

Which of the following structures is NOT part of the oral cavity?

Pharynx (B) Signup and view all the answers

What is the function of the upper esophageal sphincter?

To regulate the passage of food into the oropharynx (D) Signup and view all the answers

What is the primary function of parietal cells in the stomach?

To form inactive pepsinogen that is converted to pepsin (A) Signup and view all the answers

What is the main reason why mucous production is essential in the stomach?

To prevent the stomach lining from being damaged by pepsin (D) Signup and view all the answers

What is the name of the condition where the stomach pushes through the diaphragm?

Hiatus hernia (D) Signup and view all the answers

What is the primary function of the small intestine?

To absorb nutrients into the bloodstream (A) Signup and view all the answers

What is the name of the valve that separates the small intestine from the large intestine?

Ileocecal valve (D) Signup and view all the answers

What is the name of the cells that produce lysozyme to regulate the microbial population in the small intestine?

Paneth cells (D) Signup and view all the answers

What is the primary function of the crypts of Lieberkuhn in the small intestine?

To secrete intestinal juice (D) Signup and view all the answers

What is the name of the phase of digestion that occurs in the mouth and stomach in preparation for food?

Cephalic phase (A) Signup and view all the answers

What is the primary function of the duodenal glands in the small intestine?

To secrete alkaline mucus to prevent ulcers (C) Signup and view all the answers

What is the name of the enzyme that activates trypsin in the small intestine?

Enterokinase (D) Signup and view all the answers

What is the function of lingual glands in the tongue?

to secrete mucus and lipase (A) Signup and view all the answers

What is the pH of saliva?

Slightly acidic, ranging from 6.35 to 6.85 (B) Signup and view all the answers

Which of the following enzymes is produced by the pancreas and breaks down starch into simpler sugars?

Pancreatic amylase (D) Signup and view all the answers

What is the function of the islets of Langerhans in the pancreas?

To secrete hormones directly into the blood (C) Signup and view all the answers

What is the name of the duct that joins the common bile duct to form the hepatopancreatic duct?

Pancreatic duct (C) Signup and view all the answers

What is the main function of the papillae on the tongue?

To increase friction for forming a bolus (D) Signup and view all the answers

What is the name of the muscle that attaches to the hyoid, mandible, and styloid process of the temporal bone?

Extrinsic tongue muscle (B) Signup and view all the answers

What is the daily production of saliva in the human body?

1-1.5 liters (D) Signup and view all the answers

What is the function of lysozyme in saliva?

To kill bacteria (C) Signup and view all the answers

What is the name of the process by which the pancreas secretes pancreatic juice into the duodenum?

Exocrine function (B) Signup and view all the answers

Pair salivary glands to ducts

<h1>Parotid = Stensen's duct Sublingual = Rivinus Duct Submandibular = Whartons duct</h1> Signup and view all the answers

Which salivary gland produces the most saliva?

Submandibular Signup and view all the answers

Head of the pancreas sits?

L2 or L3 Signup and view all the answers

Hepatic Artery Proper does _% and Hepatic portal vein does _% of blood supply to liver

30 and 70 Signup and view all the answers

Trypsinogen (inactive) activates to TRYPSIN from _______

Enterokinase (brush border enzyme) Signup and view all the answers

Study Notes

Stomach

The stomach has four main regions: cardia, fundus, body, and pyloric part
The stomach is divided into two main regions: anterior and posterior surfaces
The muscularis layer of the stomach has three layers: longitudinal, circular, and oblique
The stomach has rugae, which are folds in the mucous membrane that allow for expansion
The stomach secrets gastric juices that contain pepsin, gastric amylase, and gastric lipase
The stomach mixes food with gastric juices and breaks down proteins into peptides and amino acids

Functions of the Stomach

Mechanical digestion: mixing food with gastric juices
Chemical digestion: breaking down proteins into peptides and amino acids
Secretion: producing gastric juices
Mixing: churning and breaking down food
Propulsion: moving food into the small intestine

Small Intestine

The small intestine is responsible for most of the digestion and absorption of nutrients
The small intestine has three main regions: duodenum, jejunum, and ileum
The small intestine has villi, which increase the surface area for absorption
The small intestine has microvilli, which further increase the surface area for absorption
The small intestine secrets intestinal juice that contains enzymes to break down carbohydrates, proteins, and fats

Digestion and Absorption

Digestion: breaking down of nutrients into smaller molecules
Absorption: the uptake of nutrients into the bloodstream
Chemical digestion: breaking down of nutrients into smaller molecules using enzymes
Mechanical digestion: breaking down of food into smaller pieces using the mechanical action of the digestive system

Large Intestine

The large intestine is responsible for the absorption of water, electrolytes, and vitamins
The large intestine has four main regions: cecum, colon, rectum, and anus
The large intestine has a larger diameter than the small intestine
The large intestine has haustra, which are pouches that allow for the expansion of the intestine
The large intestine secrets mucus to protect the intestinal wall from the acidic contents of the digestive system

Functions of the Large Intestine

Absorption of water and electrolytes
Absorption of vitamins
Formation and elimination of feces

Liver and Pancreas

The liver produces bile, which aids in the digestion of fats
The liver regulates blood sugar levels
The liver detoxifies the blood
The pancreas produces pancreatic juice that contains enzymes to break down carbohydrates, proteins, and fats
The pancreas regulates blood sugar levels

Phases of Digestion

Cephalic phase: preparation for food intake
Gastric phase: digestion in the stomach
Intestinal phase: digestion in the small intestine
Absorptive phase: absorption of nutrients into the bloodstream### Hepatic Sinusoids
Highly permeable capillaries between rows of hepatocytes
Receive oxygenated blood from branches of the hepatic artery
Receive nutrient-rich, de-oxygenated blood from branches of the hepatic portal vein

Blood Supply to the Liver

Hepatic artery: 30% of blood supply
Hepatic portal vein: 70% of blood supply
Central vein drains into the hepatic vein, which empties into the inferior vena cava

Portal Triad

Consists of hepatic artery, hepatic portal vein, and bile duct
Found in the portal triad area of the liver

Liver Function

Filters blood coming from the digestive system
Regulates blood sugar levels
Removes toxins and waste products from the blood

Bile Ducts

Right and left hepatic ducts merge to form the common hepatic duct
Common hepatic duct merges with the cystic duct to form the common bile duct

Gallbladder

Pear-shaped sac that stores and concentrates bile
Located in a depression on the posterior, inferior surface of the liver

Chemical Digestion

Mouth: lingual lipase, salivary amylase
Stomach: gastric lipase, pepsin (from chief cells), gastrin (hormone)
Small intestine: pancreatic amylase, lipase, proteolytic enzymes (trypsin, chymotrypsin)

Layers of the GI Tract

Mucosa: epithelium, lamina propria, mucosa-associated lymphatic tissue (MALT)
Submucosa: blood and lymphatic vessels
Muscularis: circular and longitudinal layers of smooth muscle
Serosa: outermost layer, forms the visceral peritoneum

Peritoneum

Largest serous membrane in the body
Parietal peritoneum lines the abdominal wall
Visceral peritoneum lines some organs and is their serosa layer
Peritoneal cavity: between parietal and visceral peritoneum
Peritoneal fluid: lubricating fluid in the peritoneal cavity

Peritoneal Folds

Greater omentum: largest fold, attaches to the greater curvature of the stomach
Lesser omentum: attaches the liver to the stomach
Falciform ligament: attaches the liver to the anterior abdominal wall
Mesentery: attaches the small intestine to the posterior abdominal wall
Mesocolon: attaches the transverse colon to the posterior abdominal wall

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Test your knowledge on the processes of the digestive system, including ingestion, secretion, mixing, and propulsion. Learn how the digestive system breaks down food and absorbs nutrients.

Lecture 1 Digestive System - A+P2

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