Lecture 7: Digestion Flashcards
(18 cards)
What is the primary function of the human gastrointestinal tract?
Absorption of nutrients, hydrolysis of some compounds, motility and mechanical breakdown, secretion, excretion, and defence
The gastrointestinal tract is organized as an 8m long tube with key roles in digestion and absorption.
From which embryonic layer does the main structure of the gastrointestinal tract develop?
Mesoderm
The epithelial internal lining develops from endoderm, while neurons of the GI tract come from the neural crest (ectoderm).
List the main sections of the gastrointestinal tract.
- Mouth
- Oesophagus
- Stomach
- Duodenum
- Jejunum
- Ileum
- Caecum
- Colon
- Rectum
This organization is crucial for the digestive process.
What are the three main arteries that supply blood to the gut?
- Coeliac artery
- Superior mesenteric artery
- Inferior mesenteric artery
These arteries are essential for delivering nutrients and oxygen to the gastrointestinal tract.
True or False: The enteric nervous system can function independently of the central nervous system.
True
The enteric nervous system is often referred to as the gut’s own processing system.
What are the major gut hormones and their corresponding sites of release?
- Gastrin - Stomach
- Motilin - Small intestine
- CCK - Small intestine
- GIP - Small intestine
- Secretin - Small intestine
- GLP-1 - Small and large intestine
- PYY - Small and large intestine
These hormones play significant roles in regulating digestion and metabolism.
Fill in the blank: The gastric gland organization includes _______ cells that secrete pepsinogen.
Chief cells
Pepsinogen is a precursor that becomes active in acidic conditions.
What is the role of salivary α-amylase in digestion?
It hydrolyses α (1-4) glycosidic links in carbohydrates
This enzyme is essential for breaking down starches into simpler sugars.
Describe the phases of digestion.
- Cephalic phase
- Gastric phase
- Intestinal phase
Each phase has distinct triggers and mediators that control digestive processes.
What is the primary function of the large intestine?
Salvage of nutrients, removal of bodily waste, and fermentation of indigestible materials
The large intestine plays a critical role in water absorption and processing of dietary fiber.
What are the three layers of muscle in the stomach responsible for mechanical digestion?
- Longitudinal smooth muscle
- Circular smooth muscle
- Oblique muscle
These layers work together to churn and mix food.
What is the function of the hepatic portal vein?
Transfers most gut metabolites to the liver
This includes water-soluble nutrients and drugs.
True or False: The internal anal sphincter is under voluntary control.
False
The internal anal sphincter is controlled autonomically, while the external sphincter is under voluntary control.
What is the role of brush border enzymes in the small intestine?
Local breakdown of macronutrients into absorbable components
This increases the concentration of nutrients available for absorption.
What are the three levels of folding in the small intestine that increase surface area?
- Plicae circulares
- Villi
- Microvilli
These structures are crucial for maximizing nutrient absorption.
Fill in the blank: The stomach secretes _______ to facilitate vitamin B12 absorption.
Intrinsic factor
This is essential for the absorption of vitamin B12 in the small intestine.
List the types of cells involved in gastric acid secretion.
- Parietal cells
- G cells
- Enterochromaffin-like (ECL) cells
These cells work together to regulate acid production in the stomach.
What are the primary components of digestive juices in the human gut?
- Salivary enzymes
- Gastric acid
- Bile
- Pancreatic enzymes
Each component plays a unique role in digestion and nutrient absorption.
