Digestion and Absorption

Question 1

Goal

Answer 1

turn food into energy

Question 2

Challenges associated

Answer 2

Keeping the food moving
protecting the cells
suspended things in liquid
removing liquid
Excreting but not continuously
get nutrients out of food

Question 3

Nutrition

Answer 3

process of taking in food and using it for growth, metabolism, and repair
-ingestion
-digestion
-absorption
-transport
-assimilation
-excretion

Question 4

ingestion

Answer 4

taking food and drink into the mouth

Question 5

digestion

Answer 5

breakdown food
-mechanical-physical breakdown of food
-chemical-enzymatic breakdown of chemical bonds from complex to simple

Question 6

absorption

Answer 6

moving nutrients and digested products from lumen of GI tract into the circulatory system (blood and lymph)

Question 7

transport

Answer 7

distribution of absorbed nutrients around the body via the circulatory system (blood and lymph)

Question 8

assimilation

Answer 8

incorporation of newly acquired nutrients into body cells and tissues
-growth, metabolism, repair
-uptake from blood stream

Question 9

Excretion

Answer 9

elimination of indigestible and waste products from body

Question 10

GI tract

Answer 10

25-30 feet long muscular tube that makes the digestive tract
-5 organs

Question 11

Sphincters

Answer 11

smooth muscle that opens and close regions of the tract controlling food movement from one organ to the next
-respond to stimuli from nerves, hormones, and pressure

Question 12

Digestion begins in the mouth

Answer 12

mechanical and chemical digestion
-saliva: dissolves small food particles, contains water, mucus, electrolytes, immunoglobulins, and few enzymes (cirrus=water)
-Tongue: 5 taste buds, sense of smell helps us differentiate
-chewed food gets pushed to pharynx to be swallowed

Question 13

Esophagus

Answer 13

-transport bolus and fluids to stomach
-upper esophageal sphincter: allows bolus to enter (not voluntary)
-Lower esophageal sphincter: allows the bolus of food to enter the stomach
-changes from skeletal to smooth muscle

Question 14

Stomach

Answer 14

-empty 1 cup but can go to 1 gallon
-minimal absorption (water, alc, some drugs)
-3 layers of muscle allow for mashing
-secretes gastric juices (water enzymes(pepsin and lipase) HCL and mucus)
HCL: assist protein digestion, from parietal cells, acidity prevents bacterial growth and stomach enzymes work best in a low PH

Question 15

Chyme

Answer 15

partially digested food
-leaves stomach and enters the small intestine vis pyloric sphincter
-salivary enzymes get broken down and reabsorbed

Question 16

feedback loop

Answer 16

chyme is released.
-acidity signals small intestine cells stimulate contraction of pyloric sphincter
-bicarb neutralizes environment of small intestine
-pyloric sphincter relaxes
-chyme is released

Question 17

Chemical Digestion

Answer 17

enzymes
-proteins that facilitate chem rxns as a catallyst but remain unchanged
-use hydrolysis
-water breaks bond

Question 18

3 required conditions for enzymes

Answer 18

1. compatible enzyme and nutrient are both present
2. temp of environment is optimal
   3.pH of surroundings must be in optimal range

Question 19

gastrointestinal hormones

Answer 19

gastrin, CCK, ghrelin, leptin
-activate 2nd messenger system to carry out the task usually in form of ATP or Ca

Question 20

Small Intestine

Answer 20

Duodenum, Jejunum, ileum
-3-10hrs
-mech and chem
-10 feet long surface is highly specialized for absorption

Question 21

Absorption: SI

Answer 21

villi and microvilli maximize absorption
-between villi are crypts that secrete juices, goblet secrete mucus
-villi have muscles that wave
-membranes have enzymes and pump specific to select nutrients

Question 22

Gastric Motility

Answer 22

-helps propel food along by strong muscular contractions
-peristalsis: squeezes food forward through GI tract
-Segmentation: shifts food back and forth to increase likely hood of absorption

Question 23

Liver

Answer 23

Largest internal organ
-essential in CHO metabolism
-makes proteins
-hepatocytes make bile
-site of alc metabolism
-removes toxins and hormones
-synthesizes bile: acts as emulsifier (suspends fat so enzymes can access)

Question 24

Gallbladder

Answer 24

-liver send bile via the common hepatic duct
-stores and concentrates bile
-releases bile to small intestine via common bile duct
-liver can still secrete if gallbladder is removed

Question 25

pancreas

Answer 25

exocrine gland: secretes digestive enzymes into small intestines (duct)
Endocrine: releases hormones to maintain blood glucose levels, insulin and Glucagon (blood stream)

Question 26

Small Intestines

Answer 26

-pancreas juices come into duodenum
-bicarb neutralizes stomach acid to prevent damage to absorptive surfaces of the jejunum
-enzymes for CHO, fat, PRO

Question 27

Blood and Lymph receive nutrients

Answer 27

carbs and pros are absorbed directly into blood stream- straight to liver
-fat-soluble nutrients are absorbed into the lymp system first, then delivered to blood

Question 28

illeoceal valve

Answer 28

controls flow from the small intestine to the large intestine,

Question 29

Large Intestine

Answer 29

abosrbs water and electrolytes
-cecum
colon
rectum
-1 L of fluid is gradually reduced to 200g of brown fecal material
-bile being metabolized by gut bacteria turns it brown

Question 30

Fiber

Answer 30

some fibers can not be digested and absorbed
-carry minerals, bile, additives, and contaminants out of body
-semi solid mass helps exercise the GI muscles
-bacteria in colon ferment some fibers into simpler compounds

Question 31

Defecation

Answer 31

internal anal sphincter-smooth muscle
external sphincter-skeletal muscle