the digestive system Flashcards
What are the five main phases that of digestion?
ingestion - taking food into the mouth
fragmentation- mechanically breaking down larger peices
digestion- breaking small pieces down chemically
Absorption - through cell membrane
elimination - of waste products
What are the parts of the G.I. tract?
The G.I. tract is 9 meters long and contains: Oral cavity pharynx esophagus stomach small intestine large intestine anus
What are the accessory organs of the G.I. system?
Salivary glands
gallbladder
liver
pancreas
What begins in the Oral cavity?
Ingestion
fragmentation
digestion
how many teeth does children have and adults have?
Children -20
adults- 32
Name the teeth?
from front to bacK; two incisors- for cutting One cuspid (canine) - for tearing two bicuspids (premolars) - for crushing three molars - for grinding
what are the salivary glands?
parotid
sublingual
submaxillary
what are the products secreted by the salivary glands?
amylase- breaks starch and glycogen into disaccharides
mucous - lubricates food for swallowing
describe the process of swallowing?
Tongue and pharyngeal muscles roll the bolus of food into the esophagus. The epiglottis close the airway (glottis) while swallowing. Peristalis and gravity moves it out the esophagus to the stomach.
What is Peristalsis?
The muscular movement of the G.I tract. It is controlled by the ANS.
What breaks the food further in the stomach?
muscular activity and the production of gastric juices.
What are the gastric juices made from?
The hormone gastrin and the impulses from the parasympathetic system.
What is the makeup of gastric juices?
HCL- kills organisms and keeps the pH of the stomach 2
pepsinogen - inactive enzyme. activated form is pepsin which break down peptides in the presence of low pH
What is chyme?
it is the product of food degradation in the stomach
what are globlet cells?
cells found in the stomach and the intestine the secrete mucous
What is the path of chyme?
it is secreted through the stomach muscular sphincter (pylorus) into the first part of the small intestine (the duodenum)
What is the function of the liver?
it occupies the upper right portion of the abdominal cavity. It function in: converts glucose to glycogen glucose from non carbohydrates plasma protein production deamination of proteins formation of urea storage of iron and vitamins detoxification production of bile -produce by hepatocytes in liver
What is bile?
a yellowish green fluid composed of water, cholesterol, pigments(detroyed red blood cells) and salts.
What is the function of bile salts?
emulsification of fats- the dissolving of fat globules into micelles.
emulsification helps the absorption of Vitamins A, D, E, K
What is the function of the gallbladder?
it stores bile and secrets it into the duodenum via the bile duct.
Function of pancreas in exocrine system?
it secretes pancreatic juices into the pancreatic duct which joins to the bile duct.
pancreatic juices are made up of alkaline bicarbonate ( it neutralizes acidic chyme) and digestive enzymes
What stimulates the secretion of pancreatic juices?
It is due to parasympathetic and hormonal response.
The duodenum produces and release secretin and CCK in the prescence of chyme.
What are the pancreas digestive enzymes?
pancreatic amylase - break down carbohydrates
pancreatic lipase- fat braekdown
nucleases- breakdown nucleic acids
trypsin, chymotrypsin, carboxypeptidase- breakdown proteins.
What are the components of of the small intestine?
Duodenum
jejunum
ileum
What is the role of the small intestine in the digestive system?
completes the digestion of chyme
absorbs nutrients
passes of remains to large intestines
peristalsis is the main mode of tranportation
describe absorption of the small intestine?
Because of the surface area and villi and
microvilli
both project into the lumen and contain lacteals and blood capillaries
what are lacteals?
they are lymph capillaries in villi. they absorb fats into the lyphatic system in the small intestine
What is the role of the capillaries?
They carry nutrients from small intestines to liver for processing via The hepatic portal vein (carries blood from one capillary bed to another)
What are the divisions of the large intestine?
the cecum- connects to the ileum and projects to a closed end tube
Colon
rectum- store feces
anal canal- expel feces
What are the divisions of the colon?
ascending
transverse
descending
sigmoid
How are feces formed?
The LARGE INTESTINE HAS NO digestive function.
feces are formed from water and electrolytes from residual chyme
What is feces made up of?
60% bacteria, mucus, bile pigments, water, undigested material
