Podcast
Questions and Answers
Which of the following is NOT a primary function of the alimentary canal?
Which of the following is NOT a primary function of the alimentary canal?
- Nutrient absorption
- Hormone production (correct)
- Waste elimination
- Food storage
Peristalsis is the mechanism by which food is moved through the alimentary canal.
Peristalsis is the mechanism by which food is moved through the alimentary canal.
True (A)
What is the main enzyme present in saliva, and what does it break down?
What is the main enzyme present in saliva, and what does it break down?
Salivary amylase, breaks down starch into maltose.
The process by which small molecules are taken into the bloodstream is known as ______.
The process by which small molecules are taken into the bloodstream is known as ______.
Match the following digestive structures with their function.
Match the following digestive structures with their function.
Which sphincter controls the passage of food from the stomach to the duodenum?
Which sphincter controls the passage of food from the stomach to the duodenum?
Egestion and excretion refer to the same biological process.
Egestion and excretion refer to the same biological process.
The process of breaking large insoluble food molecules into smaller soluble ones is called ______.
The process of breaking large insoluble food molecules into smaller soluble ones is called ______.
What is the name of the ball of food formed in the mouth?
What is the name of the ball of food formed in the mouth?
Bile contains enzymes that digest fat.
Bile contains enzymes that digest fat.
What is the process called that moves food down the esophagus?
What is the process called that moves food down the esophagus?
The stomach uses the enzyme ______ to break down proteins into peptides.
The stomach uses the enzyme ______ to break down proteins into peptides.
Match the enzyme with its substrate:
Match the enzyme with its substrate:
What is the pH level at which pepsin works optimally?
What is the pH level at which pepsin works optimally?
The main function of the Gall Bladder is to produce bile.
The main function of the Gall Bladder is to produce bile.
Bile contains ________ which neutralises acids.
Bile contains ________ which neutralises acids.
Which of the following are absorbed directly into the blood?
Which of the following are absorbed directly into the blood?
Lacteals absorb amino acids and sugars.
Lacteals absorb amino acids and sugars.
What is the function of the microvilli in the small intestine?
What is the function of the microvilli in the small intestine?
Digested food products are transported to the ____ via the hepatic portal vein.
Digested food products are transported to the ____ via the hepatic portal vein.
Match the following structures to their functions:
Match the following structures to their functions:
What is the approximate length of the small intestine?
What is the approximate length of the small intestine?
The large intestine primarily functions to absorb water and salts from undigested food.
The large intestine primarily functions to absorb water and salts from undigested food.
Name two adaptations of the small intestine that helps with the absorption process.
Name two adaptations of the small intestine that helps with the absorption process.
Flashcards
Bolus
Bolus
A ball of food formed by the tongue for swallowing.
Peristalsis
Peristalsis
The process of muscle contractions that move food through the oesophagus.
Oesophagus
Oesophagus
The tube that carries food from the mouth to the stomach.
Gastric Pits
Gastric Pits
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Pepsin
Pepsin
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Chyme
Chyme
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Bile
Bile
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Lipase
Lipase
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Alimentary Canal
Alimentary Canal
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Digestion
Digestion
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Absorption
Absorption
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Egestion
Egestion
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Salivary Amylase
Salivary Amylase
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Assimilation
Assimilation
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Nutrients
Nutrients
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Fatty Acids and Glycerol
Fatty Acids and Glycerol
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Lacteals
Lacteals
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Villi
Villi
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Microvilli
Microvilli
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Absorption in the Small Intestine
Absorption in the Small Intestine
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Hepatic Portal Vein
Hepatic Portal Vein
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Excellent Blood Supply
Excellent Blood Supply
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Large Intestine
Large Intestine
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Study Notes
Alimentary Canal Overview
- The alimentary canal is a muscular tube responsible for food movement, storage, digestion, absorption, and elimination.
- Food is taken into the alimentary canal via ingestion.
- Large insoluble molecules are broken down into small soluble ones through mechanical and chemical digestion.
- Small molecules are absorbed into the bloodstream during absorption.
- Small molecules are used by cells to make larger molecules (e.g., proteins) during assimilation.
- Undigested food is removed as feces in the egestion process.
- Autotrophic nutrition is where organisms make their own food (e.g., plants).
The Mouth
- Mechanical digestion in the mouth involves increasing the food surface area for chemical digestion.
- Salivary glands secrete saliva, which breaks down food into a bolus.
- The tongue forms the food into a ball called a bolus.
- The bolus is moved down the esophagus by a process called swallowing.
- Teeth are used for mechanical digestion.
Types of Teeth
- Different types of teeth (incisors, canines, premolars, and molars) have different shapes and functions, adapted to different diets.
- Carnivores (e.g., tigers) have prominent canines for tearing flesh.
- Herbivores (e.g., horses) have large molars for grinding grass.
Peristalsis
- Food is squeezed down the esophagus by wavelike muscle contractions called peristalsis.
- Circular muscles behind the bolus contract, squeezing food forward.
- Circular muscles in front of the bolus relax, allowing the lumen to widen.
Stomach Functions
- The stomach stores food (up to 2 hours) allowing time for digestion.
- Chemical digestion of proteins into peptides occurs with enzymes like pepsin, which works best at a pH of 2.
- Mechanical digestion of food happens through strong muscular contractions and relaxation, churning the food within the stomach.
- Strong acid in the stomach (pH 2) disinfects food by killing microbes.
Gastric Pits
- Glands in the stomach lining secrete:
- Mucus as a lubricant
- Hydrochloric acid to kill bacteria and maintain low pH
- Pepsin to break down proteins into peptides (optimal in acidic conditions)
Digestion in the Small Intestine
- Food exits the stomach through a sphincter.
- Chyme (partially digested food) mixes with pancreatic juices containing enzymes like:
- Amylase (starch to maltose)
- Maltase (maltose to glucose)
- Lipase (fats to fatty acids and glycerol).
- Pancreatic and intestinal juices work best at a neutral pH (7). Bile neutralizes stomach acids.
Bile
- Produced by the liver and stored in the gallbladder.
- Bile contains sodium bicarbonate, which neutralizes acids.
- Bile salts emulsify fats (break large fat droplets into smaller ones).
- Bile pigments are excreted in feces.
- Bile does not contain enzymes; it does not digest fats.
Digestion of Fats
- Bile salts emulsify large fat droplets into smaller ones, increasing the surface area for lipase action.
- Lipase digests fats into fatty acids and glycerol.
- Fatty acids and glycerol are absorbed into lacteals.
Absorption in the Small Intestine
- Small molecules (monosaccharides, amino acids, water, vitamins, and minerals) are absorbed directly into the blood.
- Fatty acids and glycerol are absorbed into lacteals, which eventually feed into the blood vessels.
The Small Intestine
- The small intestine is approximately 5 meters long.
- Finger-like projections called villi line the small intestine, greatly increasing the surface area for absorption.
- Microvilli, tiny projections on the villi, further increase the surface area for absorption.
- The small intestine has an excellent blood supply via capillaries, assisting with absorption and transport of nutrients.
- Lacteals are vessels in the villi that absorb fats.
Absorbed Food and the Liver
- Absorbed food enters the bloodstream and travels to the liver via the hepatic portal vein.
- The liver stores excess glucose as glycogen, breaks down food to release energy, and detoxifies or breaks down various substances.
The Large Intestine
- The large intestine absorbs water and salts.
- Approximately 30% of feces consists of bacteria.
- Feces are stored in the large intestine until egested via the anal sphincter.
- High-fiber diets are associated with lower incidences of bowel cancer.
Diet and Disease
- High sugar intake leads to tooth decay.
- High fat/energy intake and low exercise contribute to obesity.
- Obesity is linked to arthritis, diabetes, high blood pressure, and heart disease.
- High salt intake causes high blood pressure.
- High cholesterol contributes to heart disease.
- Low-fiber diets are linked to a higher risk of bowel cancer.
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