Ch. 9 Digestive system- NOT high yield

intracellular digestion vs extracellular digestion

• intra→ oxidation of glucose and fatty acids to make energy

• extra→ in the lumen of the alimentary canal

mechanical digestion

physical breakdown of large food particles into smaller ones

chemical digestion

enzymatic cleavage of chemical bonds, such as the peptide bonds of proteins or the glycosidic bonds of starches

the pathway of the digestive tract

oral cavity → pharynx → esophagus → stomach → small intestine → large intestine → rectum

the accessory organs of digestion

1. salivary glands

2. pancreas

3. liver

4. gallbladder

The ____ nervous system is in the wall of the alimentary canal (GI tract) and controls peristalsis. Its activity is upregulated by the parasympathetic nervous system and downregulated by the sympathetic nervous system

enteric

which hormones promote thirst

aldosterone and antidiuretic hormone (ADH or vasopressin)

which hormones promote hunger

glucagon and ghrelin

which hormones promote satiety (fullness)

leptin and cholecystokinin

in the oral cavity, mastication starts the mechanical digestion of food, while _____ ______ and _____ start the chemical digestion of food

salivary amylase, lipase

food is formed into a _____ and swallowed

bolus

what connects the mouth and posterior nasal cavity to the esophagus

pharynx

what propels food to the stomach using peristalsis

esophagus

food enters the stomach through the

lower esophageal (cardiac) sphincter

what are the 4 parts of the stomach

1. fundus

2. body

3. antrum

4. pylorus

the stomach has a lesser and a greater curvature and is thrown into folds called

rugae

which secretory cells line the stomach

1. Mucous cells

2. Chief cells

3. Parietal cells

4. G-cells

what do mucous cells do

produce bicarbonate-rich mucus to protect the stomach

what do chief cells do

secrete pepsinogen

what is pepsinogen

a protease, activated by the acidic environment of the stomach

what do parietal cells do

secrete HCl and intrinsic factor

intrinsic factor is needed for

vitamin B12 absorption

what do G-cells do

secrete gastrin

what is gastrin

a peptide hormone that increases HCl secretion and gastric motility

after mechanical and chemical digestion in the stomach, the food particles are now called

chyme

food passes into the duodenum through the

pyloric sphincter

what is the duodenum

the first part of the small intestine, primarily involved in chemical digestion

disaccharidases

brush-border enzymes that break down maltose, isomaltose, lactose, and sucrose into monosaccharides

brush-border peptidases include

aminopeptidase and dipeptidases

what does enteropeptidase do

activates trypsinogen and procarboxypeptidases, initiating an activation cascade

what does secretin do

stimulates the release of pancreatic juices into the digestive tract and slows motility

what do cholecystokinin do

stimulates bile release from the gallbladder, release of pancreatic juices, and satiety

acinar cells in the pancreas produce pancreatic juices that contain

1. bicarbonate

2. pancreatic amylase

3. pancreatic peptidases (trypsinogen, chymotrypsinogen, carboxypeptidases A and B)

4. pancreatic lipase

the liver synthesizes _____, which can be stored in the gallbladder or secreted into the duodenum directly

bile

what does bile do to fats

emulsifies them, making them more soluble and increasing their surface area

the main components of bile

1. bile salts

2. pigments (bilirubin from breakdown of hemoglobin)

3. cholesterol

the liver processes nutrients through

1. glycogenesis

2. glycogenolysis

3. storage and mobilization of fats

4. gluconeogenesis

the liver also

1. produces urea

2. detoxifies chemicals

3. activates/ inactivates medications

4. produces bile

5. synthesizes albumin

6. Synthesizes clotting factors

the gallbladder

stores and concentrates bile

which parts of the small intestine are primarily involved in absorption

jejunum and ileum

the small intestine is lined with ___, which are covered with ____, increasing the surface area available for absorption

villi, microvilli

villi contain a capillary bed and a lacteal, which is a

vessel of the lymphatic system

water-soluble compounds that enter the capillary bed

1. monosaccharides

2. amino acids

3. water-soluble vitamins

4. smally fatty acids

5. water

fat-soluble compounds that enter the lacteal

1. fats

2. cholesterol

3. fat-soluble vitamins

the large intestine absorbs

water and salts (forming semisolid feces)

the cecum

an out pocketing that accepts fluid from the small intestine through the ileocecal valves and is the site of attachment of the appendix

the colon is divided into (portions)

1. ascending

2. transverse

3. descending

4. sigmoid

the rectum stores

feces

feces is excreted through the

anus

gut bacteria produce

vitamin K and biotin (vitamin B7)