The Gastrointestinal System

• What are the main parts of the oral cavity?

  • Vestibule (space between the teeth and lips/cheeks)
  • Oral cavity proper (the area between the teeth) contains the tongue , hard and soft palates and the floor of the mouth
• What are the primary divisions of the pharynx?

  • Nasopharynx (upper part, behind the nasal cavity)
  • Oropharynx (middle part, behind the oral cavity)
  • Laryngopharynx (lower part, near the larynx)

  
• What is the function of the vestibule of the oral cavity?

  The vestibule of the oral cavity functions as the space that holds food, saliva, and assists in the movement of food between the teeth and gums during chewing and swallowing.
• What structures are located in the oral cavity proper?

  • Teeth
  • Gums
  • Tongue
  • Hard and soft palate
  • Where food is manipulated for chewing and mixing with saliva for digestion
• What is the role of the hard palate in the oral cavity?

  • Forms the anterior (front) part of the roof of the mouth.
  • Separates the oral cavity from the nasal cavity
  • Provides a firm surface against which the tongue presses during the process of chewing
• What are the key features of the soft palate?

  • Forms the posterior (back) part of the roof of the mouth
  • Composed of soft tissue.
  • Elevates during swallowing to close off the nasopharynx from the oropharynx, preventing food or liquid from entering the nasal passages.
• What structures make up the floor of the mouth in the oral cavity?

  • Formed by the mucous membrane and muscles, including the mylohyoid muscle
  • Supports the tongue and allows for the movement of food during chewing and swallowing
• What is the function of the tongue in the oral cavity?

  • Responsible for manipulating food for mastication (chewing), mixing it with saliva, and helping form a bolus (ball of food) for swallowing.
  • Aids in taste and the initiation of swallowing.
• What are the divisions of the oropharynx?

  • Located between the soft palate and the hyoid bone.
  • Serves as a passageway for both air (from the nasal cavity to the larynx) and food (from the oral cavity to the oesophagus).
  • Includes structures like the palatine tonsils.
• What structures are located in the nasopharynx?

  • Located behind the nasal cavity and above the soft palate.
  • Includes the adenoids (pharyngeal tonsils) and the openings to the Eustachian tubes (auditory tubes), which connect the middle ear to the throat.
• What is the function of the laryngopharynx?

  • Serves as the passageway for both food and air. It leads to the larynx (for air) and the oesophagus (for food).
  • Plays a key role in the protective reflexes that prevent food from entering the trachea.
• How is the oral cavity involved in the process of digestion?

  • Plays an important role in the initial stages of digestion.
  • Where mechanical digestion occurs (through chewing) and chemical digestion begins (through enzymes in saliva, like amylase).
  • The teeth, tongue, and salivary glands all aid in these processes.
• Describe the anatomical location and function of the palatine tonsils

  • Located on the lateral walls of the oropharynx, one on each side.
  • Part of the lymphatic system and help protect the body by trapping and destroying pathogens that enter the body through the mouth or nose.
• What is the significance of the epiglottis during swallowing?

  • Flap of cartilage located at the entrance of the larynx.
  • During swallowing, it moves to cover the trachea to prevent food or liquid from entering the airways, directing it into the oesophagus instead.
• What are the three divisions of the gastrointestinal system based on embryological development?

  • Foregut
  • Midgut
  • Hindgut
• What organs are included in the foregut?

  • Esophagus
  • Stomach
  • Duodenum (proximal half)
  • Liver
  • Pancreas
  • Gallbladder
  • Spleen (although it is not a direct derivative of the foregut, it receives its blood supply from the foregut's splenic artery)
• Which part of the duodenum is derived from the foregut?

  The proximal half of the duodenum is derived from the foregut. The distal half is derived from the midgut.
• What are the main organs of the midgut?

  • Duodenum (distal half)
  • Jejunum
  • Ileum
  • Cecum
  • Appendix
  • Ascending colon
  • Proximal two-thirds of the transverse colon
• Which portion of the colon is part of the midgut?

  The ascending colon and the proximal two-thirds of the transverse colon are part of the midgut.
• What organs are derived from the hindgut?

  • Distal one-third of the transverse colon
  • Descending colon
  • Sigmoid colon
  • Rectum
  • Upper part of the anal canal
• What part of the colon is derived from the hindgut?

  The distal one-third of the transverse colon, descending colon, sigmoid colon, and rectum are derived from the hindgut.
• What is the embryological origin of the spleen?

  The spleen is not derived directly from the foregut. It is derived from mesodermal tissue, but it receives its blood supply from the splenic artery, which is a branch of the celiac trunk, a branch of the foregut.
• How does the blood supply differ between the foregut, midgut, and hindgut?

  • Foregut: Blood supply comes from the celiac trunk.
  • Midgut: Blood supply comes from the superior mesenteric artery.
  • Hindgut: Blood supply comes from the inferior mesenteric artery.
• What is the clinical significance of the foregut, midgut, and hindgut divisions?

  • It helps in understanding the development of the GI tract.
  • It is used in diagnostic imaging to identify and locate gastrointestinal issues.
  • It informs surgical decisions related to blood supply and organ removal, such as in surgeries for tumours or congenital defects.
• Which structures are part of the foregut, but not part of the gastrointestinal tract itself?

  The liver, gallbladder, and pancreas are derived from the foregut, but they are accessory digestive organs, not part of the gastrointestinal tract itself.
• What is the role of the vagus nerve in the foregut and midgut?

  The vagus nerve (cranial nerve X) provides parasympathetic innervation to the foregut and midgut, influencing the motility and secretions of the digestive organs. It helps in coordinating peristalsis and enzyme secretion in these regions.
• What are the four quadrants of the abdomen, and how are they divided?

  • Right upper quadrant
  • Left upper quadrant
  • Right lower quadrant
  • Left lower quadrant
  • Divided by the intersection of two imaginary lines: a vertical line (the median plane) and a horizontal plane (the transumbilical plane)
• What does the right upper quadrant consist of?

  • Liver
  • Gallbladder
  • Right kidney
  • Parts of the small and large intestine
• What does the left upper quadrant consist of?

  • Stomach
  • Spleen
  • Left kidney
  • Pancreas
  • Parts of the small and large intestine
• What does the right lower quadrant consist of?

  • Appendix
  • Cecum
  • Right ovary (females)
  • Right fallopian tube (female)
  • Parts of the small intestine
• What does the left lower quadrant consist of?

  • Sigmoid colon
  • Left ovary (female)
  • Left fallopian tube (female)
• What are the nine regions of the abdomen and how are they divided?

  • Right hypochondriac region
  • Epigastric region
  • Left hypochondriac region
  • Right lumbar region
  • Umbilical region
  • Left lumbar region
  • Right iliac region
  • Hypogastric region
  • Left iliac region
• What are the nine regions of the abdomen based on?

  Two vertical and two horizontal planes forming a grid-like structure

  • Subcostal plane: passes through the lower ribs
  • Intertubercular plane: passes through the iliac tubercles
• What does the right hypochondriac region consist of?

  • Parts of the liver
  • Gallbladder and
  • Right kidney
• What does the epigastric region consist of?

  • Stomach
  • Liver
  • Pancreas
• What does the left hypochondriac region consist of?

  • Stomach
  • Spleen
  • Parts of the pancreas
• What does the right lumbar region consist of?

  • Ascending colon
  • Right kidney
  • Small intestine
• What does the umbilical region consist of?

  • Parts of the small intestine
  • Transverse colon
• What does the left lumbar region consist of?

  • Descending colon
  • Small intestine
• What does the right iliac region consist of?

  • Appendix
  • Cecum
  • Parts of the small intestine