Digestive System Flashcards
(38 cards)
What is Digestion?
Digestion is the process of breakdown of large complex molecules which are insoluble into simple molecules which are soluble in our body. The breakdown of these molecules is down by a chemical substance called Enzyme.
What are enzymes and 5 characteristics?
Enzymes are biological catalysts which enhance the rate of reaction.
1. it is a protein and therefore it is destroyed by heating.
2. It acts on only 1 kind of substance called the substrate.
3. It can be used several times.
4. It acts best at a particular pH
5. It always forms the same end products from the substrate.
Dental Formula for a child, adolescent and an adult?
Child - 2,1,0,2, / 2,1,0,2 = 20 milk teeth
adolescent - 2,1,2,2 / 2,1,2,2 = 28 permanent teeth
adult - 2,1,2,3 / 2,1,2,3 = 32 permanent teeth including 4 wisdom teeth.
Define Dentition.
Dentition is the arrangement of various types of teeth depending upon the food habits of an organism.
When do wisdom teeth grow?
17-20 years.
Describe the structure of a tooth.
Crown - the part exposed above the gum. It consists of the Enamel (covers the crown n is the hardest substance) and Dentine (forms bulk of the tooth and it is harder than bone but not enamel.)
Neck - slight constriction b/w crown and root.
Root - Cementum is a bone like structure covering the root and fixing it in position. The pulp is a soft connective tissue in the central space of the tooth. PULP = BLOOD CAPILLARIES, LYMPH VESSELS, NERVE FIBRES.
Name three salivary glands.
Parotid Gland - in front of each ear
Sub-mandibular Gland - each side of lower jaw
Sub-lingual Gland - below tongue
Enzyme produced in the mouth is called?
Ptyalin or salivary amylase.
The enzyme ptyalin converts what into what?
Starch —-> Maltose
Explain swallowing.
The tongue moves up and presses against the palate therefore pushing the food into the Esophagus.
What does the Epiglottis do?
The epiglottis which is present near the trachea prevents the entry of bolus into the trachea by acting like a flap and closing it.
What is Peristalsis?
It is the rhythmic wave of constrictions in the circular muscles of the gut which helps in pushing the food forward to the next part of the alimentary canal.
Stomach?
Elastic Bag located right below the Diaphragm. Protein digestion takes place here. The inner lining of the stomach secretes Gastric Juice.
What is pylorus?
It is the opening of the stomach into the small intestine.
Cardiac Sphincter is at the front end of the stomach to prevent black flow of food into esophagus.
What is Antiperistalsis?
Is when the cardiac sphincter opens and a reverse wave of muscular contraction is caused throwing food out of the mouth. It is also known as vomiting.
Gastric Juice has which enzyme? And what does it do
It activates pepsinogen to act on proteins. Pepsin digests proteins into peptides.
Which enzyme converts casein into paracasein?
Rennin
Regions of the Small Intestine?
Duodenum - Most of the digestion occurs here. 12 finger widths in length. Bile is secreted from the liver and transported through the bile duct into the duodenum. Panc juice is secreted by the pancreas and transported into the duodenum through the pancreatic duct.
Jejunum - It is always empty after death.
Ileum - Contains many enzymes. 4m long. Inner lining of the ileum is thrown into folds called villi which help in absorption.
What are the enzymes in Ileum? Enzymes in the intestinal juice?
Erepsin converts peptides into amino acids
Maltase - digests maltose into glucose.
Sucrase - splits sucrose into glucose and fructose.
Lactase - digests lactose into glucose and galactose.
Lipase - digests fats into fatty acids and glycerol.
Structure of villi and what are villi?
Villi are finger-like projections in the inner lining of ileum. They increase the surface area of the intestine which helps in the absorption of food. Between the villi there are small holes which secrete intestinal juice.
Epithelium - absorbs glucose and amino acids.
Capillaries
Lacteal - absorbs fatty acids and glycerol
Vein
Artery
Hepatic portal vein - absorbs amino acids, fructose, glucose and transports them to the liver.
Lymphatic duct
What are the adaptions of ileum for the absorption of food?
It is very long.
Villi increase the surface area for absorption.
Single-celled epithelium.
It is narrow which slows the movement of food, allowing absorption.
What is bile?
Bile is a yellowish-green fluid secreted by the liver and is transported to the small intestine through the hepatic duct.
The bile gets its yellowish-green color due to pigments such as bilirubin and biliverdin.
Bile helps convert acidic chyme to basic and does the emulsification of fats.
What is emulsification?
Emulsification is the breakdown of fats by the bile into tiny droplets for providing greater surface area for the action of enzymes.
Pancreatic Juice? Enzymes in this juice?
It is produced in the Pancreas located behind the stomach.
Amylopsin - digests starch into maltose
Trypsin - converts proteins and polypeptides into smaller peptides and amino acids
Steapsin - acts on emulsified fats to split them into fatty acids and glycerol.
