LESSON 3: A3- Human Digestion Flashcards
TRUE OR FALSE: Humans have a complete digestive system
True
The tube our food is digested through is called
the gastrointestinal tract, or GI tract for short
What is the GI tracts purpose:
ingest, digest, absorb, and egest our food
What digestion occurs in your mouth?
Chemical and physical digestion
Physical digestion in mouth
broken down physically by your teeth by tearing and cutting with your incisors and canines and by grinding and crushing with your molars
Chemical digestion in mouth
broken down chemically with your saliva which contains enzymes
Molars and premolars
Molars: teeth at back
Premolars: infront of molers
-grinding and crushing foods
Canines and incisors
Canines: sharp teeth (think dogs)
Incisors: front teeth
-Job is to grab food
What is the moist ball of food called?
bolus
Function of salivia
Helps digest foods
Amylase
- Found in saliva
Amylase is an enzyme which breaks down complex carbohydrates into smaller disaccharides
What function does mucus serve in saliva?
s a protective lubricant which helps you swallow
Where is food pushed into after swallowing?
- pushed into the pharynx and your soft palate is raised to prevent food entering your nasal passage
What happens at the same time during swalloing
At the same time the epiglottis covers the entrance to your trachea, called the glottis
This process of taking food into the body by swallowing is called
ingestion
Enzyme
any chemical produced
by cells that facilitates biochemical
reactions in the body, such as
those involved in digestion and
metabolism; all enzymes are
proteins
Once food is swallowed, it moves into the stomach through the…
esophagus
How does food move through the esophagus
stretched by the food, wave-like muscle contractions called peristalsis push the food downwards
The food enters the stomach through a circular piece of muscle called the…
gastroesophageal sphincter
peristalsis
the rhythmic, involuntary
wave-like contractions of the smooth
When does food enter the stomach?
When the gastrointenal sphincter relaxes, food can enter the J-shaped muscular organ called the stomach
What is food mixed with gastric jucies called?
chyme
Where does chyme exit from the stomach?
pyloric sphincter
TRUE OR FALSE: Lipids and carbohydrates are not digestable in the stomach
TRUE
What digestion does your stomach go through?
Chemical and physcial
Physcial digestion in stomach:
The muscle in the stomach churns and physically breaks down your food
Chemical digestion in stomach
Digestive enzymes, like pepsin which breaks down proteins, chemically digests your food
What is the hormone that breaks down food?
Gastrin
-makes the stomach release hydrochlorich acid and pepsins to break down food
pepsin
a protein-digesting enzyme
produced in the stomach
4 layers of the stomach
Intermost layer
Submucosa
Muscular
Serosa
Intermost layer
- Folded layer called mucosa
-Aecretes gastric juices
-Epithelial cells divide rapidly
Submucosa
-connective tissue
-Contains network of nerves
Muscularis
-smooth muscle
-mscles are constantly churning and mixing food with gastric jucies to produce a semi liquids called chyme
Serosa
-smooth
-outermost layer
-holds stomach in place and secretes lubricating fluid yjay eliminates friction between organs
Where does most digestion occur?
Small intestine
What does the small intestine digest?
lipids, carbohydrates, and proteins
The three sections of the small intestine
-duodenum
-jejunum
-ileum
ileum
where most of the nutrients are absorbed
jejunum
where digestion continues and some nutrients are absorbed
duodenum
where most enzymes are added
The inner surface of the small intestine is folded into many
finger-like projections
What are the finger-like projections called?
Villi.
-Each villus has capalaeries on it
-Each villus is covered with microvili
-These increase surface area in small intestine
The nutrients enter the bloodstream (i.e. are absorbed) through …
capillary beds in the villi
Types of passive transport
-Osmosis (High to low concentration)
-Dialysis (High to low concentration)
-Faciliated diffusion (High to low concentration graident but it happens with a carraer protein, which is like a door, allowing easy access to the cell memebrane)
Passive transport
Movment of materials across cell memebrane without using ATP
Active transport
- Material moved from low concentration to high conentration through a memebrane
-protien carrier is used
-ATP is used
What joins the large intestine and small intestine together?
cecum
The colon is the…
longest part of the large intestine
What are the 4 parts of the colon?
the ascending, transverse, descending and sigmoid colon
What is the last 20cm of the thelarge intestine called?
the rectum
the rectum
holds the feces until it can be eliminated, or egested, through the anus
Why do humans pass gas?
-it is produced in our intestines and occurs when our intestines cannot digest certain foods
Large intestine plays a role in absorption of…
-Water
-Ions
-Vitamins
Our large intestine houses…
Many bacteria
-some are helpful bacteria such as e.coli
-Bacteria produce vitamins K and B
Egestion
the removal of waste food materials from the body
-These would include materials like cellulose and fiber (i.e. indigestible materials), which are important as they give us a full feeling for a longer time and reduce overeating
How does Egestion work?
-Nerves in the large intestine detect the movement of food in the rectum and tells us to eject the food by a bowel movement
Microbes
-Microbes live in our intestins and carry out many different functions
End of cecum is
Apendix
What does bile do?
Bile turns hydrophobic fats and turns it into fatty acids
The beggning of the small intestine is…
duodenum
