Gastrointestinal System and Related Functions

Decreased Secretions

• Decreased juice secretion indicates a decline in functional capacity of digestive elements.
• Similar to urinary filtration, sympathetic and parasympathetic systems have major impacts on digestive functions.
• Sympathetic responses can lead to sphincters tightening, affecting digestion.

Hormonal Influences in Digestion

• The digestive tract secretes several hormones, notably:
  • Gastrin: Stimulates gastric acid secretion.
  • Secretin: Promotes pancreatic juice and bile secretions.
• Paracrine secretions (such as histamine and prostaglandins) act locally within tissues without entering the bloodstream as hormones do.
  • Example: Histamine induces inflammation but is not classified in the same way as hormones.
• Important distinction between hormone secretion (into the bloodstream) and local paracrine signaling.

Anatomy of the Oral Cavity

• Basic components to label include:
  • Frenulum and lingual frenulum
  • Uvula
  • Tonsils: Especially palatine tonsils are named after the palatine bone.
  • Teeth: Typically, adults have 32 teeth, while children have 20 deciduous teeth (baby teeth).

Understanding of the Tongue

• Different taste areas exist on the tongue (e.g., sweet, sour, bitter).
• Not emphasized on exams; focus is primarily on general structure and function.

Tooth Anatomy and Dental Health

• The hardest substance in the body: Enamel (modified bone) is important for tooth protection.
• Underneath enamel is Dentin, with microtubules that can transmit heat and potentially pain.
• Common dental issues lead to procedures like root canals, which involve accessing the innermost nerves of teeth and can be complicated and lengthy.

Swallowing and Esophageal Function

• Deglutition is the professional term for swallowing, involving 22 muscles and various cranial nerves (like Trigeminal and Facial).
• Bolus: Chewed food combined with saliva; once it passes into the stomach, it becomes chyme.
  • Peristalsis: The process of muscle contractions that pushes the bolus down the esophagus.
  • The function of the epiglottis prevents food from entering the trachea.

Stomach Functionality

• Intrinsic factor: Critical for Vitamin B12 absorption; lack can lead to pernicious anemia.
  • Stomach conditions might require removal, but needs careful management of vitamin absorption afterward.
• Digestion primarily occurs in the small intestine, where significant nutrient absorption takes place (jejunum and ileum).

Stomach Cellular Composition

• G cells: Secrete gastrin; chief cells secrete pepsinogen (inactive enzyme), and parietal cells secrete hydrochloric acid (HCl).
• HCl is essential for protein digestion, while chief cells also produce gastric lipase for fat digestion.

Hormonal Regulation

• Ghrelin: A hunger hormone secreted from cells in the stomach; potentially reduced during weight loss surgeries.
• Various gut hormones including cholecystokinin (CCK) play roles in digestion and energy balance.

Key Hormones and Their Functions

• Secretin and cholecystokinin are critical hormones impacting digestion and hormone signaling.
• Substance P: Implicated in pain pathways, relevant as it connects with gut brain signaling.

Comprehensive Understanding of the Digestive System

• Recognition of various hormones, their effects, and their interactions in the digestive process.
• Anemia types can vary, with pernicious anemia being a significant condition related to hormone and vitamin deficiencies.