What are the components of the digestive system?
What are the main processes of digestion?
What is the structure of the Gastrointestinal Tract (GIT)?
What are the key features of the mucosa in the GIT?
What role does GALT play in the digestive system?
What is the function of the lamina propria in the mucosa?
What is the muscularis mucosa responsible for?
Define absorption in the context of digestion.
Substances passing through GIT walls into blood and lymph.
What does elimination refer to in digestion?
Excretion of waste and indigestible materials.
What is the importance of digestive enzymes?
Break down carbohydrates, fats, and proteins for absorption.
What is the role of key hormones in digestion?
Regulate digestive processes and enzyme secretion.
What is the function of the submucosal plexus?
Regulates glandular secretion in the digestive system.
What types of muscle are found in the Muscularis Externa?
Name the two layers of smooth muscle in the digestive tract.
What is the peritoneum?
The largest serous membrane in the body, covering digestive organs.
What are the two layers of the peritoneum?
What is ascites?
Accumulation of fluid in the peritoneal cavity.
What is the largest fold of the peritoneum called?
Greater omentum.
What does the lesser omentum connect?
Suspends the stomach and duodenum from the liver.
What is contained in the enteric nervous system?
100 million neurons controlling gut function.
What are the two main functions of myenteric plexus?
What is the role of the submucosal plexus?
Controls glandular secretion in the digestive system.
Which system regulates the enteric nervous system?
The autonomic nervous system.
What happens to muscular activity during sympathetic stimulation?
Decreases muscular activity in the digestive system.
How does parasympathetic stimulation affect glandular secretion?
Increases glandular secretion.
What controls the strength and frequency of muscle contraction in the gut?
The myenteric plexus controls gut motility.
What does the submucosal plexus control?
It controls digestive secretions and detects sensory information.
What types of neurons are found in the enteric nervous system?
What supplies arterial blood to the GIT?
Branches of the abdominal aorta, including mesenteric arteries.
What drains nutrient-rich blood from the intestines?
The portal vein drains this blood to the liver.
What are the four basic layers of the GIT?
What is the function of the greater omentum?
It stores fat and helps protect the abdominal organs.
What is GALT?
Gut-associated lymphoid tissue, part of the immune system.
What is peristalsis?
Wave-like muscle contractions that move food through the digestive tract.
What structures line the inner surfaces of the oral cavity?
Mucous membranes.
What is the role of the uvula?
Blocks the nasopharynx to prevent food from entering the nasal cavity.
What functions does the oral cavity perform?
How many teeth do adults have?
Adults have 32 teeth.
What produces saliva?
Saliva is produced by parotid, submandibular, and sublingual glands.
What stimulates salivation in the parasympathetic nervous system?
Continuous salivation of about 1–1.5L/day.
What is the composition of saliva?
What are the main functions of saliva?
Describe the oesophagus.
What is the anatomy of the stomach?
What are the functions of the stomach?
Identify the cell types in the stomach and their functions.
What is the pH of gastric juice?
pH 2–3 (highly acidic)
How does the stomach help with iron absorption?
Stomach acid makes iron more soluble.
What triggers the enteric nervous system in the stomach?
Food distends the stomach, activating stretch receptors and chemoreceptors, which stimulate peristalsis and gastric juice flow.
What role does ghrelin play in digestion?
Stimulates hunger.
What does gastrin do?
Stimulates gastric juice secretion and motility in response to stomach distension.
What is the function of pancreatic amylase?
Breaks down starches into sugars.
What does pancreatic lipase digest?
Lipids / fats.
Which enzymes are involved in protein digestion?
What is the primary role of the gallbladder?
Stores and ejects bile for fat emulsification.
How does the gallbladder eject bile?
It contracts upon ingestion of fat.
What is emulsification in the context of digestion?
Breaks lipids into smaller molecules to increase surface area for enzymes.
Where does the majority of digestion and absorption occur?
In the small intestine.
What are the three regions of the small intestine?
What is the length of the small intestine?
6.5 meters.
What is the role of villi in the small intestine?
They maximize surface area for nutrient absorption.
What is a key function of the pancreatic juice?
It contains sodium bicarbonate and digestive enzymes.
Which hormones are secreted by the pancreas?
What structures in the small intestine increase the surface area for absorption?
What are the brush border enzymes and their primary function?
What hormone stimulates pancreatic enzyme secretion in response to fats or proteins?
Cholecystokinin (CCK)
What percentage of nutrient absorption occurs in the small intestine?
90%
How are carbohydrates absorbed in the small intestine?
What is the process for absorbing fatty acids and fat-soluble vitamins?
Where is Vitamin B12 absorbed in the intestine?
Terminal ileum (requires intrinsic factor)
What initiates fluid absorption in the gastrointestinal tract?
Osmosis from the lumen into absorptive cells.
What major functions occur in the large intestine?
What role do Peyer's patches have in the small intestine?
Contribute to immunity.
What is the role of cholecystokinin in digestion?
Stimulates bile production and gallbladder contraction.
What are the four regions of the large intestine?
What does the large intestine absorb?
What is the role of the ileocaecal valve?
Allows one-way flow from the small to large intestine.
Describe the microbial community in the large intestine.
Hosts about 100 trillion microbes; mostly symbiotic.
What do bacteria ferment in the large intestine?
Fiber to produce short-chain fatty acids (SCFAs).
What gases are produced from bacterial fermentation?
What is the process of defecation?
Mass peristaltic movements push faecal matter to the rectum.
What happens during the defecation reflex?
Rectal distension stimulates sensory impulses to the spinal cord.
What is the function of Kupffer cells in the liver?
Phagocytize foreign bodies from the blood.
What does the portal vein transport to the liver?
Nutrient- and toxin-rich blood from the GIT.
What is a role of the liver in metabolism?
Filters 1.4 liters of blood every minute.
What vitamins are produced in the large intestine?
What is the purpose of the hepatic first pass?
Transport blood from the GIT to the liver for filtration and metabolism.
What mixes in the sinusoids of the liver?
Blood from the portal vein and hepatic artery.
What is one of the liver's main functions related to toxins?
Detoxification by metabolizing drugs and toxins.
What is produced by the liver for fat digestion?
Bile.
How does the liver affect blood clotting?
Synthesizes plasma proteins and coagulation factors.
What are Kupffer cells responsible for?
Haemolysis in the liver.
What does the liver do with excess glucose?
Converts it to glycogen for storage.
What is the role of the liver in protein metabolism?
Converts essential amino acids into non-essential ones.
What is phase I detoxification?
Bio-activation involving CYP450 enzymes for metabolizing toxins.
What occurs in phase II detoxification?
Conjugation reactions to make toxins stable and water-soluble.
What compound is crucial in phase II liver detoxification?
Glutathione.
What do hydrophilic compounds do during detoxification?
They are excreted in urine or bile.
Why are ATP and nutrients important in liver detoxification?
They are highly energy and nutrient-dependent processes.
What is a key function of liver metabolism regarding fat?
Synthesizes cholesterol and triglycerides.
What are the nine anatomical quadrants of the abdomen?
Define monosaccharides.
Single sugar units; examples include glucose, fructose, galactose.
What is the major function of glucose?
Key source of energy.
Identify examples of disaccharides.
What is the composition of triglycerides?
Glycerol and three fatty acid chains.
What are the two types of fatty acids?
Explain the role of cellulose in the diet.
Acts as fiber, aiding in intestinal movement; indigestible by humans.
What is the primary storage form of energy in humans?
Glycogen, primarily stored in liver and muscles.
Define cis and trans fats.
What are the key functions of proteins?
How are amino acids absorbed in the body?
Absorbed in the small intestine after denaturation.
What allows proteins to maintain their 3D shape?
Temperature regulation
Where are amino acids absorbed in the body?
Small intestine
List some key functions of proteins.
What are amino acids known as?
The basic building blocks of proteins
What does it mean to denature a molecule?
To destroy its properties
What is the significance of the lock and key model in proteins?
It refers to the unique 3D structure of each protein.
What are enzymes classified as?
Biological catalysts
How do enzymes affect chemical reactions?
They speed them up thousands of times.
What model describes enzyme specificity?
The lock and key model
What suffix do many enzyme names end with?
-ase (e.g., lactase)
What happens to enzymes during chemical reactions?
They are not changed or consumed.
How can proteins be denatured?
By changes in pH and temperature.
What are the components of the digestive system?
What are the main processes of digestion?
What is the structure of the Gastrointestinal Tract (GIT)?
What are the key features of the mucosa in the GIT?
What role does GALT play in the digestive system?
What is the function of the lamina propria in the mucosa?
What is the muscularis mucosa responsible for?
Define absorption in the context of digestion.
Substances passing through GIT walls into blood and lymph.
What is the importance of digestive enzymes?
Break down carbohydrates, fats, and proteins for absorption.
What is the function of the submucosal plexus?
Regulates glandular secretion in the digestive system.
What types of muscle are found in the Muscularis Externa?
Name the two layers of smooth muscle in the digestive tract.
What are the two main functions of myenteric plexus?
What happens to muscular activity during sympathetic stimulation?
Decreases muscular activity in the digestive system.
What controls the strength and frequency of muscle contraction in the gut?
The myenteric plexus controls gut motility.
What does the submucosal plexus control?
It controls digestive secretions and detects sensory information.
What types of neurons are found in the enteric nervous system?
What supplies arterial blood to the GIT?
Branches of the abdominal aorta, including mesenteric arteries.
What drains nutrient-rich blood from the intestines?
The portal vein drains this blood to the liver.
What is the role of the uvula?
Blocks the nasopharynx to prevent food from entering the nasal cavity.
What stimulates salivation in the parasympathetic nervous system?
Continuous salivation of about 1–1.5L/day.
What is the composition of saliva?
What are the main functions of saliva?
Describe the oesophagus.
What is the anatomy of the stomach?
What are the functions of the stomach?
Identify the cell types in the stomach and their functions.
What triggers the enteric nervous system in the stomach?
Food distends the stomach, activating stretch receptors and chemoreceptors, which stimulate peristalsis and gastric juice flow.
What does gastrin do?
Stimulates gastric juice secretion and motility in response to stomach distension.
What is emulsification in the context of digestion?
Breaks lipids into smaller molecules to increase surface area for enzymes.
What is the role of villi in the small intestine?
They maximize surface area for nutrient absorption.
What is a key function of the pancreatic juice?
It contains sodium bicarbonate and digestive enzymes.
What are the brush border enzymes and their primary function?
What hormone stimulates pancreatic enzyme secretion in response to fats or proteins?
Cholecystokinin (CCK)
How are carbohydrates absorbed in the small intestine?
What is the process for absorbing fatty acids and fat-soluble vitamins?
What initiates fluid absorption in the gastrointestinal tract?
Osmosis from the lumen into absorptive cells.
What major functions occur in the large intestine?
What is the role of cholecystokinin in digestion?
Stimulates bile production and gallbladder contraction.
What are the four regions of the large intestine?
Describe the microbial community in the large intestine.
Hosts about 100 trillion microbes; mostly symbiotic.
What happens during the defecation reflex?
Rectal distension stimulates sensory impulses to the spinal cord.
What is the purpose of the hepatic first pass?
Transport blood from the GIT to the liver for filtration and metabolism.
What is one of the liver's main functions related to toxins?
Detoxification by metabolizing drugs and toxins.
What is the role of the liver in protein metabolism?
Converts essential amino acids into non-essential ones.
What occurs in phase II detoxification?
Conjugation reactions to make toxins stable and water-soluble.
Why are ATP and nutrients important in liver detoxification?
They are highly energy and nutrient-dependent processes.
What is a key function of liver metabolism regarding fat?
Synthesizes cholesterol and triglycerides.
What are the nine anatomical quadrants of the abdomen?
Explain the role of cellulose in the diet.
Acts as fiber, aiding in intestinal movement; indigestible by humans.
What is the primary storage form of energy in humans?
Glycogen, primarily stored in liver and muscles.
Define cis and trans fats.
List some key functions of proteins.
What is the significance of the lock and key model in proteins?
It refers to the unique 3D structure of each protein.
In today's lecture, we will cover the structure and functions of the digestive system, key enzymes and hormones in digestion, and types of dietary macronutrients.
Key Phrase: "You are what you eat." - Importance of digestion and absorption in nutrition. - Factors affecting remaining waste in the body.
Large intestine (including rectum and anal canal)
Accessory Organs:
The GIT consists of four main layers: 1. Mucosa 2. Submucosa 3. Muscularis 4. Serosa (peritoneum)
Largest serous membrane: - Parietal Layer: Covers abdominal walls. - Visceral Layer: Covers organs. - Fluid: Provides lubrication.
Complex network that controls GI functions independent of the CNS but regulated by it: - Myenteric Plexus: Controls muscle contractions. - Submucosal Plexus: Manages digestive secretions.
Pancreatic enzymes: - Amylase, Lipase, Trypsin, Chymotrypsin, etc. - Essential for breaking down macronutrients (fats, proteins, carbs).
Functions include: - Absorption of water and vitamins - Fermentation by intestinal flora - Formation of feces - Consists of cecum, colon, rectum, and anal canal.
Biological catalysts: - Speed up reactions. - Highly specific for substrates (lock and key model).
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