Digestive System Flashcards
What are the four accessory organs to the GI system?
- Salivary glands
- Gallbladder
- Liver
- Pancreas
How many teeth do kids and adults have?
Kids: 20 deciduous teeth
Adults: 32 permanent teeth
What are the types of teeth (from front to back)
- Two incisors (cutting)
- One cuspid/canine (tearing)
- Two bicuspids/premolars (crushing)
- three molars (grinding)
What are the salivary glands and what do they secrete?
- Parotid
- Sublingual
- Submaxillary
Secretes mucous and salivary amylase
What does salivary amylase do?
Splits starch and glycogen into disaccharide subunits
What is the scientific term for swallowing?
Deglutition
What are the two layers of muscle in the esophagus?
- Inner circular layer
- Outer longitudinal layer
These produce peristalsis, which is modulated by the ANS
Which division of the ANS stimulates the GI system?
The parasympathetic nervous system
Which cells in the protect the lumen of the stomach from gastric juices?
Mucous secreting goblet cells
What can increase the production of gastric juice? (2)
- Gastrin (stomach hormone)
- Parasympathetic impulses
What are the two important components of gastric juice?
- HCl to keep pH at 2, kills microorganisms and aids in hydrolysis
- Pepsinogen (inactive enzyme: zymogen) is converted to pepsin in presence of low pH. Pepsin digests proteins
Chyme is squirted through a sphincter (called what) into what?
The pylorus, into the duodenum.
Give some functions of the liver (8)
- Conversion of glucose to glycogen (glycogenesis)
- Synthesis of glucose from non-carbohydrates (gluconeogenesis)
- Production of plasma proteins
- Destruction of erythrocytes
- Deamination of amino acids and formation of urea
- Storage of iron and certain vitamins
- Alteration of toxic substances (detoxification)
- Exocrine role (eg. production of bile by hepatocytes)
What is bile?
Produced by hepatocytes (liver cells), bile is mainly composed of water, cholesterol, pigments (from destruction of erythrocytes) and salts.
The bile salts have a digestive function (emulsification of fat into micelles). Emulsification also helps in the absorption of fat soluble vitamins A, D, E and K
It is stored in the gallbladder (a small muscular sac) and secreted into the duodenum via the common bile duct
What are the 4 fat soluble vitamins?
- Vitamin A (retinal, carotenoids)
- Vitamin D (cholecalciferol, ergocalciferol)
- Vitamin E (tocopherols, tocotrienols)
- Vitamin K (phylloquinone, menaquinones)
What do the hormones secretin and CCK do when they are released by the duodenum in response to the presence of chyme?
Cholecystokinin makes the pancreas secrete alkaline bicarbonate ions (to neutralize acidic chyme)
Secretin makes the pancreas secrete digestive enzymes
True or false? The pancreas has endocrine and exocrine functions?
True
Endocrine: islets of Langerhan, insulin and glucagon
Exocrine: Bicarbonate ions and digestive enzymes
What are the digestive enzymes secreted by the pancreas? (6)
- Pancreatic amylase
- Pancreatic lipase
- Nucleases
- Trypsin
- Chymotrypsin
- Carboxypeptidase
PLANT can be used to remember most of these (not including chymotrypsin and trypsin)
What are the three divisions of the small intestine (in order)?
- Duodenum
- Jejunum
- Ileum
Peristalsis is primary mode of transport in all these.
What absorbs fat in the small intestine?
Lacteals in villi absorb most fat into the lymphatic system
Nutrients (other than fats) get absorbed how in the small intestine?
Absorbed in blood capillaries in the villi bordering the lumen. These are taken directly to liver via the hepatic portal vein.
What are three major features of epithelium in the lumen of the small intestine?
- Villi
- Microvilli (brush border)
- Goblet cells (excess mucous lubricates and protects against acids, enzymes etc.)
What are the divisions of the large intestine?
- Cecum (connects to the ileum and projects closed end tube/appendix)
- Colon (ascending, traverse, descending and sigmoid portions; the rectum and the anal canal)
What is feces?
- Water
- Undigested material
- Gut flora (60% dry weight!)
- mucous
- Bile pigments (responsible for poo colour)
What are some mutualistic symbiotic functions of gut flora (bacteria)? (5)
- Fermenting unused energy substrates
- Training the immune system
- Preventing harmful species growth
- Producing vitamins for host (eg. vitamin K)
- Producing bile pigments
What are the intestinal folds called?
Plicae circulares
How do kidneys respond to a decrease in glomerular blood pressure (usually a result of decreased blood pressure)?
By activating the renin-angiotensin system of hormones. This increases the amount of sodium and water that is reabsorbed by the kidneys, therefore increasing blood volume and pressure.
What is the source, target, triggers and effects of gastrin?
It is from gastric mucosa and acts on the stomach. It is triggered by food in the stomach and psychic factors. It results in increased HCl secretion and gastric emptying
What is the source, target, triggers and effects of CCK?
It is from the duodenal mucosa and acts on the gallbladder and pancreas. It is triggered by amino acids, peptides and fatty acids in the duodenum. It causes contractions of gallbladder and secretion of pancreatic juice.
What is the source, target, triggers and effects of secretin?
It is secreted from gastric mucosa and acts on the pancreas. It is triggered by acid in the duodenum and causes increased bicarbonate secretion.
What is the source, target, triggers and effects of enterogastrone?
Also known as gastric inhibitory peptides, enterogastrone is secreted by duodenal mucosa and acts on the stomach. It is triggered by fat digestion products in the duodenum.
It causes decreased gastric emptying.
