topic 8 (gastrointestinal system) Flashcards
Describe the anatomy of the alimentary canal.
Mouth: Oral cavity where food intake and initial digestion occur.
Pharynx: Passageway for food from the mouth to the esophagus.
Esophagus: Muscular tube transporting food from the pharynx to the stomach.
Stomach: Large, muscular sac that mixes food with gastric juices for digestion.
Small Intestine: Comprised of the duodenum, jejunum, and ileum; site of most digestion and nutrient absorption.
Large Intestine: Includes the cecum, colon, rectum, and anus; absorbs water and forms feces.
Describe the anatomy of the liver and gallbladder.
Liver:
*Lobes: Divided into right and left lobes.
* Hepatocytes: Functional cells of the
liver.
* Bile Ducts: Transport bile produced by
the liver.
* Portal Vein: Brings nutrient-rich blood
from the digestive organs.
* Hepatic Artery: Supplies oxygenated
blood to the liver.
Gallbladder:
* Location: Underneath the liver.
* Function: Stores and concentrates
bile.
* Cystic Duct: Connects the gallbladder to the common bile duct.
Describe the anatomy of the pancreas.
- Location: Behind the stomach.
- Parts: Head, body, and tail.
- Ducts: Pancreatic duct merges with the
common bile duct to deliver digestive
enzymes to the duodenum. - Islets of Langerhans: Clusters of cells producing insulin and glucagon.
Describe the functions of the alimentary canal.
- Mouth: Mechanical digestion by chewing; chemical digestion of carbohydrates by salivary amylase.
- Stomach: Mechanical digestion by churning; chemical digestion of proteins by pepsin and acid.
- Small Intestine: Enzymatic digestion of nutrients; absorption of nutrients into the bloodstream.
- Large Intestine: Absorption of water and electrolytes; formation and elimination of faeces.
Describe the functions of the liver, gallbladder, and pancreas.
- Liver: Produces bile; processes nutrients; detoxifies harmful substances; stores glycogen, vitamins, and minerals.
- Gallbladder: Stores and concentrates bile; releases bile into the small intestine to aid in fat digestion.
- Pancreas: Produces digestive enzymes (exocrine function); secretes insulin and glucagon to regulate blood sugar (endocrine function).
Describe the mechanism of swallowing.
- Oral Phase: Voluntary phase where the tongue pushes the bolus to the back of the mouth.
- Pharyngeal Phase: Involuntary reflex triggered as the bolus enters the pharynx; the epiglottis covers the trachea to prevent aspiration.
- Esophageal Phase: Involuntary peristaltic waves move the bolus down the esophagus to the stomach.
Describe how digestion and appetite are regulated.
- Neural Regulation: Enteric nervous system controls gastrointestinal motility and secretion; autonomic nervous system modulates activity.
- Hormonal Regulation: Hormones like gastrin, secretin, cholecystokinin (CCK), and ghrelin regulate digestive processes and appetite.
- Appetite Control: Hypothalamus regulates hunger and satiety; influenced by hormones like leptin and ghrelin.
Describe the processes of ingestion, breakdown, and absorption of nutrients.
- Ingestion: Intake of food via the mouth.
- Breakdown: Mechanical digestion (chewing, churning) and chemical digestion (enzymes breaking down macromolecules).
- Absorption: Nutrients absorbed primarily in the small intestine through villi and microvilli into the bloodstream and lymphatic system.
Describe the elimination of waste products.
- Large Intestine: Absorbs remaining water and electrolytes from indigestible food matter.
- Formation of Feces: Undigested material, bacteria, and waste products form feces.
- Defecation: Feces are expelled from the body through the rectum and anus.
Outline the swallowing process.
- Oral Phase: Voluntary control where food is chewed and mixed with saliva to form a bolus.
- Pharyngeal Phase: Involuntary phase initiated when the bolus reaches the pharynx; epiglottis closes to prevent food from entering the airway.
- Esophageal Phase: Involuntary peristaltic contractions push the bolus down the esophagus into the stomach.
These flashcards cover the essential aspects of the gastrointestinal system, providing a comprehensive overview of its anatomy, functions, and processes.
