topic 3: digestive system Flashcards
what is homeostatsis?
ability of an organism or cell to maintain internal equilibrium by adjusting its physological processes
What are the 4 major processes of the digestive system?
- Ingestion
- Digestion
- Absorption
- Egestion
what is ingestion?
taking in food
-mouth
what is digestion?
breaking down food (mechanical and chemical)
-mouth and stomach intestine
What is absorption?
making nutrients in food available to your circulatory system
-small intestine
what is egestion?
getting rid of indigestiable food
-large intestine
what is the order of digestion in body parts?
- mouth
- pharynx
- esophagus
- stomach
- small intestine
- large intestine
- anus
what do teeth aid in?
mechanical digestion by chewing food into smaller pieces
what is mastication?
chewing
what does chewing help with?
easier swallowing and faster chemical breakdown in digestive tract
what do canines do?
rip
what do incesors do?
shred
what do molars do?
grind
what does saliva contain?
the enzyme amylase, which chemically breaks down starches
what does saliva do to food?
softens it
what tates are taste buds sensitive to?
sweet, salty, sour and bitter
what happens when you first eat food?
it is rolled into a small ball called a bolus which is passed to the back of the throat and swallowed.
what does the epiglottus do when swallowing?
closes the turchea
ingestion starts both what two types of digestions?
chemical and mechanical
what is the pharynx?
the “crossroad” between mouth, nose, trachea and esophagus
what is the esophagus?
25cm long muscular tube that functions to transport food and liquids from the pharynx to the stomach by waves of muscular contractions (peristalsis)
is perstalsis involuntary?
yes
Where does food enter the stomach?
Though the cardiac lower esophageal sphincter
What part of the stomach creates inactive enzymes?
The upper portion (fundus)
Where do enzymes become active?
In the lower portion of the stomach (pycloric) as they begin to take part in chemical digestion
Where does food leave the small intestine through?
Pyloric sphincter
How much food can the stomach hold?
2-4L
How many layers and there names within the stomach?
3 layers, longitudinal, circular and oblique (diagonal) rows
What do the 3 muscles help with?
Squeeze and churn the food (mechanical)
Where are gastric glands located
In the wall of the stomach
What do gastric glands produce?
Hydrochloric acid and pepsinogen
What is pepsinogen?
An inactive form of an enzyme called a precursor
What does HCL do in the stomach?
Kills bacteria, breaks down food and provides the right pH for enzymes to work
What do mucous cells do?
Secrete protective coating against HCL
What happens to pepsinogen in the presence of HCL?
Converted to an active form of pepsin
-pepsin acts on proteins and breaks them down into smaller pieces
What does lipase do in the stomach ?
Starts the breakdown of lipids
What is the soupy mixture of food and digestive juices called after 3-5 hours ?
Chyme
What does chyme do?
Stimulated the pycloric valve to open and food moves into small intestine
