Chapter 3 Flashcards
What do organ systems do?
work together to support the entire organism
What is digestion?
process of breaking down food into components small enough to be absorbed by the body (physical and chemical)
What is absorption?
process of taking substances into the interior of the body (lymph and blood stream)
Gastrointestinal tract
muscular
hollow tube consisting of the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus
Transit time
amount of time it takes food to pass the entire length of the GI tract
Sphincters
circular, muscular valves
Feces
body waste
including unabsorbed food residue, bacteria, and dead cells
What things make you want to eat?
sight, smell, texture, taste, hearing
cephalic portion of digestion (thought(
hunger
appetite
When does digestion start?
cephalic phase the first thought of food hypothalamus involuntary control pituitary
What happens to food in the mouth?
digestion and taste
How does digestion take place in the mouth?
mouth physically digests via chewing and swallowing
mouth chemically digests via amylase in saliva to break down food
What does the mouth taste?
sweet, sour, salty, bitter, umami
Salivary amylase
breaks down carbs
Lipase
breaks down lipids
Bicarbonate
for acidity
What does saliva contain?
salivary amylase bicarbonate mucus lingual lipase (infants) antibodies and lysozyme
How do we swallow food?
voluntary and involuntary phase
What is the voluntary phase of swallowing food?
chewing
can choose how many times you chew
30 is standard
What is the involuntary phase of swallowing food?
once you swallow
reflex
epiglottis covers the voice box and trachea moves up
Esophagus?
from mouth to stomach
How does food move through the whole GI tract?
via peristalsis and segmentation
What is peristalsis?
tightening of the lumen to move food down
What is segmentation?
breaking into smaller pieces
mechanical digestion
What does the stomach do?
acts as a holding and mixing tank
doesn’t do much digestion
holds some water, fats, and 20% alcohol
What does the stomach secrete?
gastrin
What does gastrin trigger the release of?
pepsinogen HCL Intrinsic factor Pepsin Gastric Lipase Mucus Bicarbonate
What gives the stomach its pH?
HCL
What is intrinsic factor?
necessary for B12 absorption
What is gastrin?
stomach hormone
Where are gastric juices produced?
in gastric pits of stomach lining
What is the purpose of bicarbonate?
acts as antacid
The release of mucus and bicarbonate relies on what?
prostaglandins
What can inhibit prostaglandin production?
NSAIDs
What can a reduced mucus barrier lead to?
ulcers
What sphincters are located near the stomach?
gastroesophageal
pyloric
What causes heartburn?
esophageal sphincter opens and allows backflow into esophagus
In what people is GERD common?
pregnant women
infants (Caucasian and Asian descent)
middle-aged, Caucasian, overweight, male with poor diet
What are peptic ulcers?
open sores that develop in the lining of the esophagus, stomach, or upper portion of the small intestine
What is the most common cause of stomach ulcers?
bacteria
H. pylori
What aggravates ulcers?
stress, spicy food etc
What does the small intestine do?
main digester and absorber
What is the anatomy of the small intestine?
Duodenum
Jejunum
Illeum
What is the purpose of the villi and microvilli in the small intestine?
increases surface area
used for absorption
What is the physiology of the small intestine?
moves and makes chyme with digestive juices
villi lined with enterocytes to absorb
secretes enzymes and absorbs nutrients
What are the four different types of nutrient absorption?
- passive diffusion
- facilitated diffusion
- active transport
- phagocytosis and pinocytosis
What materials move through the body via phago and pinocytosis?
large quantities
bulk
how fats move around body
What are the gastrointestinal accessory organs?
liver
gallbladder
pancreas
What is meant by accessory organs?
not in direct contact with GI tract
What does the liver produce?
bile
What does the liver contain?
cholesterol
What does the liver emulsify?
fats
What happens to bile once it reaches the ileum?
mostly reabsorbed in the ileum
returned to the liver
What is it called when bile is returned to the liver after hitting the ileum?
enterohepatic circulation
