Unit 5 Structure List: Anatomy of the Respiratory, Digestive, and Abdominal Vessels

Respiratory System

Overview

The respiratory system is responsible for the exchange of gases (oxygen and carbon dioxide) between the body and the environment. It consists of a series of airways and associated structures.

• Nares/Nostrils: External openings of the nose that allow air entry.

• Nasal cavity: The internal space behind the nose, lined with mucosa to warm and filter air.

• Nasopharynx: The upper part of the pharynx, connecting the nasal cavity to the oropharynx.

• Oropharynx: The middle part of the pharynx, behind the oral cavity.

• Laryngopharynx: The lower part of the pharynx, leading to the larynx and esophagus.

• Larynx: Also known as the voice box; contains the vocal cords and is involved in sound production.

• Epiglottis: A flap of cartilage that covers the trachea during swallowing to prevent food from entering the airway.

• Vocal cords: Folds of tissue in the larynx that vibrate to produce sound.

• Trachea: The windpipe; a tube that carries air from the larynx to the bronchi.

• Carina: The ridge at the base of the trachea where it divides into the right and left primary bronchi.

• Phrenic n.: The phrenic nerve innervates the diaphragm, playing a crucial role in breathing.

• Cricoid cartilage: A ring-shaped cartilage of the larynx, located below the thyroid cartilage.

• Primary bronchus (R and L): The first branches of the trachea that lead to each lung.

• Secondary bronchus (R and L): Branches of the primary bronchi that supply each lobe of the lungs.

• Lungs (R and L, including lobes): The main organs of respiration, divided into lobes (3 on the right, 2 on the left).

• Diaphragm: The primary muscle of respiration, separating the thoracic and abdominal cavities.

Digestive System

Overview

The digestive system is responsible for the breakdown and absorption of nutrients. It consists of the alimentary canal and associated organs.

• Mouth: The entry point for food, where mechanical and chemical digestion begins.

• Esophagus: A muscular tube that transports food from the pharynx to the stomach.

• Stomach: A muscular organ that mixes food with gastric juices for digestion.

• Pyloric sphincter: A muscular valve controlling the passage of food from the stomach to the duodenum.

• Duodenum: The first part of the small intestine, where most chemical digestion occurs.

• Jejunum: The middle section of the small intestine, primarily involved in nutrient absorption.

• Ileum: The final section of the small intestine, which absorbs remaining nutrients.

• Ileocecal valve: A sphincter controlling the flow from the ileum to the cecum.

• Major duodenal papilla: The opening in the duodenum where bile and pancreatic juices enter from the common bile duct and pancreatic duct.

• Cecum: The first part of the large intestine, receiving material from the ileum.

• Appendix: A small, tube-like structure attached to the cecum; its function is not fully understood.

• Ascending colon: The portion of the large intestine that travels upward on the right side of the abdomen.

• Hepatic flexure (right colic flexure): The bend between the ascending and transverse colon, near the liver.

• Transverse colon: The horizontal portion of the large intestine.

• Splenic flexure (left colic flexure): The bend between the transverse and descending colon, near the spleen.

• Descending colon: The portion of the large intestine that travels downward on the left side.

• Sigmoid colon: The S-shaped final part of the large intestine, leading to the rectum.

• Rectum: The final section of the large intestine, storing feces before elimination.

• Anus: The opening at the end of the digestive tract for expelling waste.

• Liver: A large organ involved in metabolism, detoxification, and bile production.

• Gallbladder: A small organ that stores and concentrates bile produced by the liver.

• Cystic duct: The duct that carries bile from the gallbladder to the common bile duct.

• Common hepatic duct: The duct formed by the union of the right and left hepatic ducts, carrying bile from the liver.

• Common bile duct: The duct formed by the union of the common hepatic and cystic ducts, delivering bile to the duodenum.

• Pancreas: An organ with both endocrine (insulin production) and exocrine (digestive enzyme production) functions.

• Main pancreatic duct: The duct that carries digestive enzymes from the pancreas to the duodenum.

• Ampulla of Vater: The dilation where the common bile duct and main pancreatic duct join and empty into the duodenum.

• Rugae: Folds in the lining of the stomach that allow expansion as the stomach fills.

Vessels of the Abdomen

Overview

The abdominal cavity contains major blood vessels that supply and drain the digestive organs and other abdominal structures.

• Celiac trunk: A major branch of the abdominal aorta that supplies the stomach, liver, and spleen.

• Splenic artery: Supplies blood to the spleen.

• Common hepatic artery: Supplies blood to the liver.

• Hepatic proper artery: A branch of the common hepatic artery that supplies the liver.

• Superior mesenteric artery: Supplies blood to the small intestine and part of the large intestine.

• Inferior mesenteric artery: Supplies blood to the distal part of the large intestine.

• Mesentery: A fold of peritoneum that attaches the intestines to the posterior abdominal wall, providing support and containing blood vessels.

• Renal arteries (R and L): Supply blood to the kidneys.

• Inferior vena cava: The large vein that returns deoxygenated blood from the lower body to the heart.

• Greater omentum: A large fold of peritoneum that hangs from the stomach and covers the intestines.

• Abdominal aorta: The main artery of the abdomen, supplying blood to abdominal organs.

• Falciform ligament: A ligament that attaches the liver to the anterior abdominal wall and diaphragm.

Key Abdominal Vessels Table

The following table summarizes the main arteries and their supplied regions:

Artery	Supplied Region
Splenic artery	Spleen
Common hepatic artery	Liver (via hepatic proper artery), stomach, duodenum
Hepatic proper artery	Liver
Superior mesenteric artery	Small intestine, proximal large intestine
Inferior mesenteric artery	Distal large intestine

Additional info:

• The phrenic nerve is essential for diaphragmatic movement and thus for breathing.

• The ampulla of Vater is clinically significant as a site where gallstones may lodge, causing obstruction.

• The mesentery not only supports the intestines but also serves as a conduit for blood vessels, nerves, and lymphatics.