Digestion part 1 Flashcards
what is digestion
the process of breaking down nutirents and abosrbing it into blood and carrying it to cells
4 main steps
ingestion
digestion
absorption
egestion
2 types of digestion
mechanical - when food breaks down in mouth from teeth
chemical - mouth, stomach food is coated in enzymes that break it down
specialized digestive systems 1
single sac (gastrovascular cavity) entrance for food exit for waste ex. jelly fish
specialized systems 2
more complex animals have a tract with 2 openings. special systems that help with breaking down
what is the human digestive system also known as
gastrointestinal tract (GI tract) 7-9m long
what does it interact with
circulatory system, nervous, endocrine system
what does the digestive system consist of
mouth, pharynx, esophagus tube, stomach, small intestine, large intestine, rectum and anus
accescory organs
salivary glands, pancreas, liver and gallblader
what does the mouth do
physical digestion - food is broken down into smaller bits by teeth
incisors and canine
good for grabbing and ripping apart food
pre molars and molars
good for grinding food and crushing food
how does chemicaal digestion work in the mouth
chemical digestion - breaks down food using saliva and acid
what is in saliva
enzymes are in saliva these help speed up the chemical breakdown. most important is amylase
what does amylase do
breaks down starch into disacchrides
what does saliva do
breaks down food and allows you to taste food
what aids swollowing
mucose
how much is saliva is prodced everyday
.75 - 1.5 L
how is a bolus formed
water from saliva moistens the food into a bolus
what safety mechanisms
soft palate is raised so food does not go into nasal cavity
larnyx is raised to stop food from entering into the epiglottis and stops food from entering the lungs
what is the esophagus
moves food from the mouth into the stomach
what happens in the esophagus
walls stretch so that food can get pushed down this is also known as paristalses
how long does it take to reach the stomach
8 seconds
what is the stomach
j shaped muscle, chemical and mechanical digestion, expands 2 L, covered in rugae
what can de digested in the stomach
proteins can be digested. lipids and carbohydrates cannot
what does the sphincters do
controlls movement of food in and out of stomach
what does the cardiac sphincter do
when relaxed food can enter the stomach, when contracted food cannot move back into the esophagus
4 layers of the stomach (inner most - outer most)
mucosa
sub mucosa
muscularis
serosa
what controlls digestion
enzymes, hormones and nerves
what hormone is released during digestion in the stomach
gastrin when nerves sense the food
what is gastrin made of
mucose, acid, digestive enzymes
ph level of acid
2-3
what happens when pepsinogen is activated
it becomes pepsin which breaks down protein
if the gastroesophageal sphincter does not close…
acid from the stomach can come up into the esophagus. can cause heart burn
what causes acid reflex
over filled stomach and smokingand cardiac sphincter does not close properly
what bacteria can stomach acid not kill
helicobactor pylori can not be killed and can lead to stomach ulcers
