p.4
Digestion in the Small Intestine
What do proteases catalyze?
The breakdown of some proteins into peptides and some into amino acids.
p.5
Adaptations of the Small Intestine for Absorption
What structures in the villi help transport absorbed food molecules?
Lacteal and the capillary network.
p.6
Role of the Liver in Digestion and Metabolism
How does the liver regulate blood glucose levels?
By converting excess sugar, starch, and proteins into lipids stored in adipose tissue.
p.1
Human Digestive System Structure
What are the digestive glands in the human body?
Salivary glands, liver, and pancreas.
p.4
Digestion in the Small Intestine
What is the role of sodium hydrogencarbonate in the small intestine?
It neutralizes the acidic chyme and provides an alkaline medium for enzyme action.
p.4
Digestion in the Small Intestine
What is the function of lactase?
It catalyzes the breakdown of lactose into glucose and galactose.
p.4
Absorption of Nutrients
What process draws water into the blood in the capillaries?
Osmosis, due to increased water potential in the lumen.
p.3
Digestion in the Stomach
How does mucus protect the stomach?
It prevents the stomach wall from being digested by pepsin or damaged by hydrochloric acid.
p.6
Egestion and Formation of Stools
What do stools contain?
Dietary fibers, bacteria, secretions from the alimentary canal, dead cells from the intestinal wall, and water.
p.5
Absorption of Nutrients
What is absorbed in the large intestine?
Remaining water, minerals, and vitamins.
p.2
Types of Teeth and Their Functions
What is the function of enamel?
Protects the teeth from wearing down due to chewing.
p.6
Role of the Liver in Digestion and Metabolism
What vitamins does the liver convert and store?
It converts carotene into vitamin A and stores lipid-soluble vitamins such as A and D.
p.1
Human Digestive System Structure
What are the main components of the human digestive system?
The alimentary canal and digestive glands.
p.1
Human Digestive System Structure
What is the pathway of the alimentary canal?
Mouth cavity → pharynx → esophagus → stomach → duodenum → ileum → caecum → colon → rectum → anus.
p.4
Digestion in the Small Intestine
What does intestinal juice mainly contain?
Water, mucus, and sodium hydrogencarbonate.
p.3
Digestion in the Stomach
What is the function of the pyloric sphincter?
It relaxes to release food from the stomach into the duodenum.
p.2
Types of Teeth and Their Functions
What is the main composition of enamel?
Mainly made of calcium salts.
p.2
Types of Teeth and Their Functions
What does the pulp cavity contain?
Living cells, blood vessels, and nerve fibers.
p.6
Role of the Liver in Digestion and Metabolism
How does the liver detoxify harmful substances?
By breaking down drugs and alcohol into harmless substances that are passed out of the body.
p.2
Digestion in the Mouth
How does water in saliva aid digestion?
It dissolves soluble substances in food so that we can taste it.
p.5
Adaptations of the Small Intestine for Absorption
What feature of the small intestine increases the surface area for absorption?
The highly folded inner wall with numerous villi.
p.5
Adaptations of the Small Intestine for Absorption
What role does peristalsis play in the small intestine?
It brings digested food molecules into close contact with the villi for absorption.
p.5
Absorption of Nutrients
How are water-soluble molecules transported from the small intestine to the rest of the body?
Through capillaries in villi to the hepatic portal vein, then to the liver and beyond.
p.2
Physical vs. Chemical Digestion
Why is physical digestion significant?
It increases the surface area of food for digestive juices to act on.
p.6
Egestion and Formation of Stools
How do stools exit the body?
They pass out of the body through the anus.
p.5
Adaptations of the Small Intestine for Absorption
How does the one-cell thick epithelium of the small intestine benefit absorption?
It shortens the distance for diffusion.
p.6
Role of the Liver in Digestion and Metabolism
What is the pathway for the transport of lipids and lipid-soluble molecules?
Lacteal in villi of small intestine → main lymph vessel → vein near the neck region → vena cava → heart → aorta → other parts of the body.
p.6
Role of the Liver in Digestion and Metabolism
What process does the liver use to break down excess amino acids?
Deamination, converting amino groups to urea, which is released into the blood and excreted through urine.
p.2
Physical vs. Chemical Digestion
What is physical digestion?
The breaking down of food into small pieces by physical actions.
p.2
Physical vs. Chemical Digestion
What is an example of physical digestion?
Chewing, churning, and emulsification by bile.
p.4
Absorption of Nutrients
How are water-soluble food molecules absorbed in the small intestine?
By diffusion and active transport into the capillaries.
p.3
Digestion in the Small Intestine
What is the function of bile in digestion?
It emulsifies lipids into small droplets to increase the surface area for pancreatic lipase.
p.3
Digestion in the Small Intestine
What is the function of pancreatic amylase?
It catalyzes the breakdown of starch into maltose.
p.5
Adaptations of the Small Intestine for Absorption
Why is the small intestine very long?
To allow sufficient time for absorption.
p.2
Types of Teeth and Their Functions
What type of tissue is dentine?
Living tissue containing calcium salts.
p.2
Digestion in the Mouth
What does salivary amylase do?
Catalyzes the breakdown of starch into maltose.
p.1
Types of Teeth and Their Functions
Describe the features of canines.
Pointed and curved with 1 root, used for tearing flesh.
p.3
Digestion in the Stomach
What role does hydrochloric acid play in gastric juice?
It provides an acidic medium for pepsin and kills bacteria in food.
p.6
Role of the Liver in Digestion and Metabolism
What happens to the iron released from the breakdown of old red blood cells in the liver?
It is stored and can be reused for making new red blood cells.
p.4
Digestion in the Small Intestine
What does sucrase break down?
Sucrose into glucose and fructose.
p.2
Types of Teeth and Their Functions
What are the three layers of a tooth?
Enamel, Dentine, and Pulp cavity.
p.4
Absorption of Nutrients
Where are lipid-soluble vitamins absorbed?
Into the lacteal (a lymph vessel) by diffusion.
p.3
Digestion in the Small Intestine
What are bile pigments?
Waste products formed from the breakdown of hemoglobin of red blood cells, excreted in stools.
p.1
Types of Teeth and Their Functions
What is the function of premolars?
Crushing and grinding food.
p.2
Physical vs. Chemical Digestion
What is chemical digestion?
The breaking down of large food molecules into small ones.
p.3
Digestion in the Small Intestine
What does pancreatic lipase break down?
Lipids into glycerol and fatty acids.
p.4
Adaptations of the Small Intestine for Absorption
What is one adaptation of the small intestine for absorption?
The presence of villi increases surface area for absorption.
p.3
Digestion in the Small Intestine
What does sodium bicarbonate do in the small intestine?
It neutralizes acidic chyme and provides an alkaline medium for enzyme action.
p.2
Digestion in the Mouth
What is the function of mucus in saliva?
Sticks food particles together and lubricates food for easier chewing and swallowing.
