Digestive System Flashcards
Intracellular Digestion:
The oxidation of glucose and fatty acids to
make energy.
Extracellular Digestion:
Process by which nutrients are obtained from
food. Occurs in alimentary canal.
Mechanical Digestion:
Physical breakdown of large food molecules
into smaller particles.
Chemical Digestion:
The enzymatic cleavage of chemical bonds
such as the peptide bonds of proteins or the
glycosidic bonds of starches.
Peristalsis:
Rhythmic contractions of the gut tube
What is the effect of ADH and aldosterone on thirst?
Increase thirst
Effect of glucagon and ghrelin on hunger?
Increase hunger
Effect of leptin and cholecystokinin on satiety
Increase satiety
Describe the digestive pathway
Oral cavity –> pharynx –> esophagus –> stomach –> small intestine –> large intestine –> rectum
Duodenum
First part of small intestine. A basic (pH = 8.5) environment. Site of the
majority of chemical digestion.
Disaccharidases:
Brush-border enzymes that break down maltose,
isomaltose, lactose, and sucrose into monosaccharides.
Aminopeptidase &
Dipeptidase:
Brush-border peptidases
Enteropeptidase
Activates trypsinogen and procarboxypeptidases.
List the enzymes in the duodenum
dissaccharidases, aminopeptidases, enteropeptidase
Hormones in the duodenum
Secretin and cholecystokinin
Secretin:
: Peptide hormone. Stimulates release of pancreatic
juices and slows motility.
Cholecystokinin
Stimulates bile release from gallbladder, release of
pancreatic juices, and satiety.
List the two enzymes that start the chemical digestion of food
amylase and lipase
What prevents food from entering the larynx?
The epiglottis
What connects the mouth to the esophagus?
Pharynx
What are the four parts of the stomach?
fundus, body, antrum, pylorus
List the 4 secretory cells that line the stomach
Mucous cells, chief cells, parietal cells, and G cells
Mucous Cells
Produce bicarbonate-rich mucus to protect
stomach wall from acid.
Chief Cells
Secrete pepsinogen, a protease activated by the
acidic environment.
Parietal Cells:
: Secrete HCl and intrinsic factor, which is needed for
vitamin B12 absorption.
G-Cells:
Secrete gastrin, a peptide hormone that increases HCl
secretion & gastric motility.
Which structures of the small intestine are primarily involved in absorption?
jejunum and ileum
What is the small intestine lined with ?
Villi which are covered with microvili
Villi:
: Capillary Bed: Absorbs water-soluble nutrients.
Lacteal: Absorbs fat, sends to lymphatic system.
Fat soluble vitamins
A D E K
Water soluble vitamins
all other vitamins that aren’t fat soluble
What does the large intestine do?
Absorbs water and salts and forms feces
Cecum
Outpocketing that accepts fluid from small
intestine through ileocecal valve. Site of
attachment of the appendix.
Structure of the colon
Ascending / transverse / descending / sigmoid
Gut bacteria
Produce vitamin K and biotin (vitamin B7).
Pancreas:
Acinar Cells produce pancreatic juices that contain
bicarbonate, pancreatic amylase, pancreatic peptidases,
and pancreatic lipase.
Liver:
Synthesizes bile, albumin and clotting factors. Process
nutrients. Detox: NH3 –> Urea, as well as alcohol & drugs.
Liver receives blood from the abdominal portion of
digestive tract via Hepatic Portal Vein.
Gallbladder
Stores & concentrates bile. CCK stimulates bile release into
biliary tree, which merges with pancreatic duct.
