07_Digestive System 1 Flashcards
Complete the phrase: ‘You are what you _______.’
digest
Name the components of the digestive system.
- Mouth
- Pharynx
- Oesophagus
- Stomach
- Small intestine
- Large intestine (incl. rectum and anal canal)
- Accessory organs (salivary glands, pancreas, liver, gall bladder and biliary tract)
What are accessory organs?
Organs that support the functions of the digestive system.
List the processes of digestion.
- Ingestion
- Secretion
- Mixing
- Propulsion
- Digestion
- Absorption
- Elimination
What is the mucosa?
The innermost layer of the gastrointestinal tract (GIT).
What are the three layers of the mucosa?
- Epithelium
- Lamina propria
- Muscularis mucosa
What type of epithelium is found in the stomach and intestines?
Columnar epithelium.
What is the function of goblet cells in the mucosa?
Secretion of mucus to lubricate food and protect against digestive juice erosion.
What does GALT stand for?
Gut-Associated Lymphoid Tissue.
What percentage of the body’s immune cells are contained in GALT?
70%.
What is the function of the muscularis mucosa?
Creates villi to increase surface area for absorption and digestion.
What is contained in the submucosa?
- Blood and lymph vessels
- Submucosal plexus (neurons)
- Glands and lymphatic tissue
What are the two muscle layers in the muscularis externa?
- Inner circular muscle
- Outer longitudinal muscle
What is the role of the myenteric plexus?
Controls strength and frequency of muscle contractions for gut motility.
What is the peritoneum?
The largest serous membrane in the body, providing a physical barrier to the spread of infection.
What are the two layers of the peritoneum?
- Parietal
- Visceral
What is ascites?
The accumulation of fluid in the peritoneal cavity.
What is the greater omentum?
The largest fold of the peritoneum that drapes over the transverse colon and small intestine.
What is the function of the lesser omentum?
Suspends the stomach and duodenum from the liver; serves as a pathway for blood vessels.
What is the enteric nervous system?
The brain of the gut, extending from the oesophagus to the anus.
How many neurons does the enteric nervous system contain?
100 million.
What are the two types of plexuses in the enteric nervous system?
- Myenteric plexus
- Submucosal plexus
What is the function of the submucosal plexus?
Controls digestive secretions and detects sensory information.
What supplies arterial blood to the GIT?
Branches of the abdominal aorta, including the mesenteric arteries.
What is the role of the liver in relation to the GIT?
Filters blood and processes nutrients before they enter systemic circulation.
What does the term ‘peristalsis’ refer to?
Involuntary muscle contractions that propel food through the digestive tract.
What are the functions of saliva?
- Digestion
- Lubrication
- Cleansing of oral cavity and teeth
- Defence
- Taste
- Buffer
- Waste removal
What is contained in saliva?
- Water (99.5%)
- Mineral salts
- Enzymes
- Mucus
- Immunoglobulins
- Blood clotting factors
What is the function of the oesophagus?
A muscular tube that transports food to the stomach via peristalsis.
What is the role of the lower oesophageal sphincter?
Prevents reflux of stomach contents into the oesophagus.
What are the four main regions of the stomach?
- Cardia
- Fundus
- Body
- Pyloric
What is peristalsis?
Muscular contractions that move food through the digestive tract
Peristalsis is essential for the movement of food along the gastrointestinal tract.
What is the function of the epiglottis?
Prevents food from entering the trachea
The epiglottis is a flap of elastic cartilage that plays a crucial role in swallowing.
What does the lower oesophageal sphincter do?
Acts as a seal on the stomach to prevent reflux of stomach contents into the oesophagus
This sphincter is also known as the cardiac sphincter.
What are the four main regions of the stomach?
Cardia, fundus, body, pyloric
These regions have specific roles in the digestive process.
How many layers of muscle does the stomach have?
Three layers of muscle
This is more than the two layers found in the rest of the gastrointestinal tract.
What does gastric juice consist of?
Hydrochloric acid (HCl) and mucus
The stomach secretes 2–3L of gastric juice daily, which is highly acidic.
What is the role of parietal cells in the stomach?
Secrete intrinsic factor and hydrochloric acid
Intrinsic factor is essential for vitamin B12 absorption.
What is the function of chief cells in the stomach?
Secrete pepsinogen and gastric lipase
Pepsinogen is converted to pepsin by HCl for protein digestion.
What does the stomach use to protect against acid?
Mucus produced by goblet cells
This mucus acts as a barrier to the acidic environment.
What hormone stimulates hunger?
Ghrelin
Ghrelin is produced in the stomach and signals the brain to stimulate appetite.
What is the pancreas’s exocrine function?
Secretes pancreatic juice into the small intestine
This juice contains enzymes and bicarbonate to aid digestion.
What are the primary enzymes secreted by the pancreas?
- Trypsin
- Chymotrypsin
- Pancreatic lipase
- Pancreatic amylase
These enzymes are crucial for digesting proteins, fats, and carbohydrates.
What is the gallbladder’s primary function?
Stores and ejects bile to emulsify fats
Bile is essential for the digestion and absorption of dietary fats.
What is the pH range of bile?
7.6–8.6 (mildly basic)
This pH helps in the emulsification of fats.
What are the three regions of the small intestine?
- Duodenum
- Jejunum
- Ileum
Each region has distinct roles in digestion and absorption.
What is the primary function of villi in the small intestine?
Increase surface area for absorption
Villi contain blood capillaries and lacteals for nutrient absorption.
What role do brush border enzymes play in the small intestine?
Facilitate the final stages of digestion on the intestinal lining
These enzymes are essential for breaking down carbohydrates and proteins.
What hormone is released in response to high fat or protein chyme in the duodenum?
Cholecystokinin (CCK)
CCK stimulates bile release and pancreatic enzyme secretion.
What is the primary role of the large intestine?
Final stages of digestion, absorption, and stool formation
It also plays a role in vitamin synthesis through bacterial activity.
What are the four regions of the large intestine?
- Caecum
- Colon
- Rectum
- Anal canal
Each region contributes to different functions in the digestive process.
What is the role of microbes in the large intestine?
Aid in nutrient extraction and produce short-chain fatty acids
These microbes support gut health and contribute to metabolism.
What triggers the defecation reflex?
Distension of the rectal wall
This triggers sensory impulses that lead to muscle contractions for stool expulsion.
What is the primary function of the liver?
Cleansing blood of microbes and detoxification
The liver has over 500 functions, including metabolism and nutrient storage.
What is the hepatic first pass?
Transport of nutrient-rich blood from the GIT to the liver for filtration
This process is essential for detoxifying substances before they enter systemic circulation.
What is the hepatic first pass?
All blood from the GIT is transported to the liver via the portal vein to be filtered/metabolised before entering systemic circulation.
What are the two main sources of blood that mix in the liver?
Portal vein and hepatic artery.
What is the primary function of Kupffer cells in the liver?
Haemolysis.
List three functions of the liver.
- Cleansing blood of microbes
- Detoxification of drugs and toxins
- Bile production and secretion
What is the role of the liver in hormone homeostasis?
Deactivating all hormones.
What is the liver’s role in metabolism?
- Metabolism of glucose (glycogen)
- Fats (hepatocytes store triglycerides)
- Amino acids.
What is thermogenesis in the context of liver function?
Heat production.
What is stored in the liver?
- Vitamins (A, D, E, K, B12)
- Iron
- Copper
- Glycogen.
What happens to excess glucose in the liver?
Converted to glycogen for storage.
What is the function of hepatocytes in detoxification?
Convert toxins into non-toxic metabolites for excretion.
True or False: The liver is highly energy dependent for detoxification.
True.
What are the two major classifications of chemical compounds regarding detoxification?
- Hydrophilic
- Lipophilic.
Fill in the blank: Phase I of detoxification involves _______ enzymes.
[CYP450 family of]
What is the purpose of Phase II in detoxification?
Conjugation reactions to neutralize toxins and make them water-soluble.
What is cellulose and its function in the human digestive system?
Indigestible fibre that assists with the movement of materials through the intestines.
What is the primary short-term energy storage molecule in the body?
Glycogen.
What are triglycerides composed of?
- Glycerol
- Three fatty acid chains.
What is the role of cholesterol in the body?
Vital for cell membrane integrity, vitamin D synthesis, and sex hormone synthesis.
What distinguishes cis and trans fatty acids?
Cis configuration has H atoms on the same side of the double bond; trans has them on opposite sides.
What is the percentage of body mass that proteins constitute?
15%.
What must happen to proteins before protease enzymes can cleave amino acids?
Proteins must be denatured.
What are enzymes?
Biological catalysts that speed up chemical reactions.
How are enzyme names typically formed?
Based on the substrate they react with, usually ending in –ase.
Fill in the blank: Proteins are easily denatured by _______ and changes.
[pH]
