Let’s start our journey through oral cavity!
Teeth
Those white hard walls are teeth.
They can physically break down food into small pieces.
Mouth
Now we are in the mouth
where the digestion begins!
Tongue
Salivary Glands &
Salivary Amylase
Wow! Three salivary glands are working! Of cource their job is to produce saliva. Besides moistening food, there are some litter workers called salivary amylase(neutral pH). They are enzymes which is in charge of breaking down starch into maltose. That’s the first step of chemical digestion of carbohydrates~
Do you feel this soft muscle? It’s called the tongue, which contributes to chewing, swallowing,and sensing food.
Still in the oral cavity...
Pharynx
Here is called pharynx.
Both the air passage and food passage cross in there!
Epiglottis
Have you seen the moving tissue?
When human beings swallow the food,
the epiglottis helps to keep food
from entering the trachea.
Esophagus
Aha! We are in the esophagus~ You can feel the pressure from the muscle. This is the process of peristalsis. We can reach the stomach soon~
Here comes to the abdominal cavity!
Stomach
Cardiac sphincter
Interestingly, the stomach can both physically and chemically digest food. Churning is a physical digestion process which results in the acid chyme.
You can see the colorless and transparent liquid. That’s gastric juice, which is composed by hydrochloric acid. HCl is beneficial since it kills bacteria with its high acidity. BTY! HCl reacts with pepsinogen and produces pepsin(acidic pH 3.5) for chemical digestion of proteins which will be broke down into peptides.
Forgot to metion! HCl can burn the lining of the stomach, so mucous is made to protect the stomach linling. If the stomach gets burned, it’s called an ulcer, which may lead to bleeding or emergency situations!
Cardiac sphincter, or lower esophageal sphincter, is where we are right now! Yes, you’re right! We almost get the stomach.
Pyloric sphincter
Oh! The pyloric sphincter is closed. Let’s wait untill next open. At the bottom of the stomach, the pyloric sphincter allows little amounts of chyme to enter the intestine.
Continues in the abdominal cavity
Liver
During the waiting time, we can have a close-up view of the liver, the largest gland in the body! It’s reeeeeally important since it has diversified functions! I’ve made a list for you~
- Produces bile
- Destroys old red blood cells and converts hemoglobin to a product in bile
- Produce urea through deamination
- Makes blood proteins from amino acis
- Detoxifies the blood by removing poisonous substances and metabolizing them into harmless substances
- Maintains glucose level of blood
- Stores glucose as glycogen after eating, and break down glycogen to glucose during eating
Gallbladder
The bile produced by the liver is stored in the gallbladder, a pear-shaped, muscular sac attached to the surface of the liver. Emulsification is the process that breaks down fat into fat droplets with bile.
Have you seen the organ which lies deep under the stomach? It is the pancreas which has both endocrine and exocrine functions! It secrets insulin and glucagon, hormones that keep the blood glucose level as an endocrine gland. We will focus more on its exocrine during our tour. The pancreatic juice contains pancreatic amylase(basci pH 7.5), trypsin(basci pH 7.5),lipase(basci pH 7.5), and sodium bicarbonate. Each product has own specific function. Let me introduce to you one by one.
Pancreatic amylase, trypsin, and lipase are three digestive enzymes in the pancreas.
Pancreatic amylase is an enzyme which breaks down starch into maltose. Although it’s produced in the pancraes, this process occurs in the duodenum.
Trypsin is a kind of proteases as pepsin. It’s used to break down proteins to peptides.
Lipase is another enzyme which is used to break down fat droplets into glucerol and fatty acids.
Sodium bicarbonate( NaHCO) helps to neutralize the stomach acid.
Pancreas
Let’s go ahead!
Pelvic cavity
Small intestine
The small intestine is the last station for food digestion. It is responsible for absorption of molecules like amino acids, glucose, fatty acids, and glycerol. Proteins and carbohydrates are digested by intestinal juices. Maltase(basci pH 7.5) converts maltose to glucose and peptidase(basci pH 7.5) breaks down peptides.
Do you know how huge the surface area of the small intestine is? It can almost cover a tennis court! BUT why? The secret is those fingerlike projections called villi on the convoluted intestine wall. Each villus has tiny microvilli on columnar epithelial cells and within each villus are blood vessels and a small lymph vessel called a lacteal which absorbs fluids and returns it to the veins later. The folded walls, villi and microvilli all contributes to increase the surface area of the interior of the small intestine.
Duodenum
The duodenum is the first 10 inches of the small intestine. Enzymes from the pancreas digest all 3 food groups: proteins, fats, and carbohydrates.
The mesentary exists to sustain and support certain portions of the small intestine from the abdomen.
Large intestine
Time passes quickly! The large intestine is tha last site of the abdominal cavity. Its main function is the absorption of water and vitamins from undigested food. Also, it contains a large quantity of E.coli bacterial which consume any substances that were not digested earlier. These bacteria produce some vitamins, essential amino acids and other growth substances required by the body. When E.coli substances are broke down, they give off odorous molecules which causes odor of feces.
Rectum & anus
In pelvic cavity, rectum temporarily
stores undigested food and anus
takes charge of elimination,or defecasion.
Thank you~
Hope you enjoy the jouney!!
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Funghi in the human body
Hi, I'm your tour guide Funghi~
Hope you enjoy the journey!
Before start, I need to introduce you our route. We will go sightseeing along the alimentary canal, also called digestive tract, pathway by which food enters the human body and solid wastes are expelled. This tour includes the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus.
Are you ready for the amazing adventure?!
LET'S GO!
Digestive System Travel Brochure