Digestive System Flashcards
What is the function of the throat?
-It is a muscular passage which connects the mouth to the esophagus and is the site of swallowing.
What two structures prevent food from entering the air passages and how do they do this?
-Epiglottis- A flap of tissue that covers the opening to the trachea during swallowing.
-Soft palate- Soft tissue which covers the roof of the mouth and the back of the oral cavity. During swallowing, the soft palate moves back and closes off the nasopharynx which leads to the nasal cavities.
-The tongue and the muscular walls of the pharynx help move food to the back of the mouth which stimulates the swallowing reflex.
What is the function of the esophagus?
-It is a short muscular tube which carries the food from the pharynx to the stomach.
-The food is pushed along the esophagus due to peristalsis.
What is the function of the cardiac sphincter?
-It prevents back flow of food from the stomach and back into the esophagus.
What is the structure of the stomach?
-The walls of the stomach consist of 3 layers of smooth muscle.
-The stomach wall is lined with a layer called mucosa, which is highly folded and contains millions of gastric glands.
What do the gastric glands produce and what are their functions?
-HCl- Kills bacteria in food and activates the formation of the enzyme pepsin.
-Mucous- Lubricates the food and protects the stomach walls from HCl and pepsin.
-Pepsin- Begins the chemical digestion of protein. (protein + H2O = polypeptide chains).
What form is food in after it leaves the stomach, and what is the last structure it passes through?
-Food is in a semi liquid state called acid chyme. The acid chyme passes through a second ring like muscle, called the pyloric sphincter which controls the amount of food moving into the small intestine.
What is the function of the small intestine?
-Chemical digestion of carbohydrates, proteins, fats, and nucleic acids.
-Absorption of glucose, amino acids, fatty acids and glycerol, and the components of nucleotides.
What is the function of mouth?
-Ingestion of food. Mechanical and chemical digestion occur in the mouth.
-The teeth and tongue mechanically digest food, which increasing the surface area for digestive enzyme action.
-The tongue helps mix food with saliva.
-Saliva lubricates food before swallowing and produces the enzyme salivary amylase.
What is the structure of the small intestine?
-The small intestine is the long section of the digestive tract. This helps to maximize the time in surface area for absorption.
-The walls of the small intestine are highly folded, which increase the surface area for absorption. The inner surface of the small intestine has large folds, called mucosal folds those the large mucosal folds have small folds called villi.
What is the function of the duodenum?
-The duodenum is majority of chemical digestion occurs.
-The duodenum is lined with millions of intestinal glands, which secrete the enzymes necessary for chemical digestion.
What is the function of bile?
-Bile is produced by the liver and stored in the gallbladder and ducts from both join and empty into the duodenum.
-partially digested, fat and protein in the duodenum stimulates the gallbladder to release bile.
-Bile contains bile salts, which emulsify fats and therefore increase the surface area of fat in preparation for chemical digestion.
What is the function of pancreatic juice and what does pancreatic juice consist of?
-Pancreatic juice is secreted by the pancreas and released when acid chyme enters the duodenum.
-Pancreatic juice contains sodium bicarbonate pancreatic amylase, trypsin, lipase nuclease.
What do the lining of the walls of the intestine contain?
-The lining of the walls of the intestine contain intestinal glands, which complete the chemical digestion of proteins, fats, carbohydrates, and nucleic acids.
-The intestinal glands produce intestinal juice, which contains the enzymes maltase, lactase, and sucrase. These enzymes complete the chemical digestion of carbohydrates.
-The intestinal juice also contains peptidases, which completes the chemical digestion of proteins.
-The intestinal juice also contains nucleosides, which completes the chemical digestion of nucleic acids.
When and where does absorption occur and what structure allows absorption to occur?
-Absorption of nutrient molecules takes place once a chemical digestion is complete the absorption of nutrient molecules.
-Absorption occurs mainly in the jejunum and ileum, because they are highly specialized for absorption.
-The inner surface of the jejunum and ileum are lined with villi. Each bill is contains a capillary network containing blood and electric containing lens which nutrients particles are absorbed into.
