22-1: Digestive Processes and Histology

Question 1

What are the functions of the digestive system?

Answer 1

to take in food, break it down into tiny nutrient molecules, absorb these molecules into the bloodstream, and rid the body of indigestible remains

Question 2

What are the two sets of organs in the digestive system?

Answer 2

the GI tract (where food passes thru) and the accessory organs (food doesn’t pass thru them)

Question 3

GI Tract

Answer 3

long muscular tube winding thru the body, which digests food (breaks it down into small fragments) and absorbs the digested pieces through its lining into the blood. Includes:

mouth
pharynx
esophagus
stomach
small intestine
large intestine
anus

Question 4

accessory organs

Answer 4

produce or store secretions that aid in the breakdown of food, and release them into the GI tract through duct, making them exocrine glands. Includes:

salivary glands
liver
gall bladder
pancreas

Question 5

What are the 6 digestive processes?

Answer 5

ingestion
propulsion
mechanical digestion
chemical digestion
absorption
defecation

Question 6

ingestion

Answer 6

process of taking food into the GI tract (occurs int he mouth)

Question 7

propulsion

Answer 7

the process that moves food through the GI tract. Includes swallowing (oropharynx) and peristalsis (esophagus to intestines)

Question 8

peristalsis

Answer 8

wavelike contractions of the smooth muscle in the walls of the GI tract that squeeze food from one organ to the next

(“peristalsis pushes” - linear motion of outer layers)

Question 9

segmentation

Answer 9

rhythmic local constrictions

“segmentation squishes” - circular motions of inner layers

Question 10

mechanical digestion

Answer 10

physically breaking down the food into smaller pieces, including chewing, mixing of food with saliva by tongue, churning of food in stomach, and segmentation in intestines

Question 11

chemical digestion

Answer 11

series of catabolic steps in which complex food molecules are broken down into their monomers with the help of enzymes

Question 12

absorption

Answer 12

the passage of digested end products from the lumen of the GI tract into the blood or lymph. The major site for this process is the small intestine

Question 13

defecation

Answer 13

the elimination of indigestible substances from the body via the anus in the form of feces

Question 14

What are the four tissue layers of the GI tract, from deep to superficial?

Answer 14

mucosa
submucosa
muscularis
serosa

Question 15

mucosa

Answer 15

moist layer of epithelial tissue lining the lumen of the tube from mouth to anus

Question 16

what are the functions of the mucosa?

Answer 16

1. secretion of mucus and digestive enzymes
2. absorption of the end products of digestion into the blood
3. protection against infection (from lymph nodes - MALT)

Question 17

lamina propria

Answer 17

capillaries for absorption, lies under the epithelial tissue in the mucosa

Question 18

submucosa

Answer 18

layer of dense connective tissue that binds the mucosa to the muscularis. Highly vascular and contains elastic fibers that enable the stomach to regain its normal shape after stretching

Question 19

muscularis

Answer 19

two layers of smooth muscle (inner circular and outer longitudenal) - contractions of this layer mix food with digestive juices (segmentation) and propel it through the GI tract (peristalsis).

Question 20

sphincters

Answer 20

circular layer of musclaris thickens to act as valves to prevent back flow and control food passage from one organ to the next

Question 21

serosa

Answer 21

protective outermost layer covering organs in abdomen. formed of connective tissue covered by a single layer of squamos epithelial cells

Question 22

visceral peritoneam

Answer 22

aka serosa, covers organs in abdomen

Question 23

parietal peritoneum

Answer 23

lines walls of abdominal cavity

Question 24

peritoneal cavity

Answer 24

space between the parietal and visceral peritoneam, filled with serous fluid

Question 25

peritonitis

Answer 25

inflammation of the peritoneal cavity