Digestive System Flashcards
What is the digestive tract (aka alimentary tube)?
A muscular tube that runs from mouth to anus. It is a complex system with many layers.
What are the two different types of lining in the digestive tract?
1.Mucosa
- Epithelial lining
- Consists of secretion, absorption,
endocrine cells
2. Submucosa
- Layer of connective tissue
- Supports blood vessels, lymphatic
vessels, and nerves
What are the two different types of lining in the digestive tract?
1.Mucosa
- Epithelial lining (protective layer)
- Consists of secretion, absorption,
endocrine cells
2. Submucosa
- Layer of connective tissue (glue)
- Supports blood vessels, lymphatic
vessels, and nerves (holds them
together)
What are three smooth muscle layers in the digestive tract?
Longitudinal layer
- Arranged along length of tract
- Shortens and lengthens
Circular layer
- Ring around lumen (lumen means
inside space)
- Constricts lumen
Oblique layer
- Twists and turns
- Only located in stomach
- Rumbles
Explain the longitudinal layer of smooth muscle
It is a layer of muscle arranged along the length of tract, which shortens and lengthens.
Explain the circular layer of smooth muscle
It is a ring around the lumen (which means empty space), that constricts it.
Explain the oblique layer of smooth muscle
This is a layer of muscle only found in the stomach, which twists and turns. This causes the rumbling sound.
What are the four steps of digestion?
- Ingestion
- Digestion
- Absorpion
- Egestion/Elimination
What is mechanical digestion?
The physical breaking down of solid food masses, which mostly occurs in the mouth and stomach
What is chemical digestion?
The chemical breaking down of mechanically digested food, through various juices. These juices contain enzymes that break food down to molecules.
What is ingestion?
The intake of food.
What is digestion?
The preparation of food for absorption, which occurs in the alimentary canal
What is absorption?
The removal and storage of valuable nutrients, which occurs primarily in small intestine.
What is egestion/elimination?
The excretion of waste through the rectum and anus
What is the purpose of the mouth?
The mouth is where ingestion occurs and where the digestive process begins. Teeth aid in the mechanical digestion of food.
What is the purpose of the salivary glands?
The salivary glands are an accessory organ which secretes saliva, mucous, and salivary amylasse. These begin the chemical breakdown of carbohydrates.
What is the purpose of the pharynx?
The pharynx is a pipe where you’re still both eating and breathing through. Logitudinal and circular muscles ensure that the food moves down (peristalsis).
What is peristalsis?
It is the operation of circular and logitudinal muscles which help move food along the digestive tract. They are so strong that we can digest food even upside down!
What is the esophagus?
The pipe that connects the pharynx to the stomach.
What is bolus?
Bolus is the name for ood that has already passed through the mouth, and thus the chemical and mechanical digestion that occurs there.
What are sphincters?
Sphincters are ring-shaped muscles that contract and dilate, effectively regulating the flow of materials through the digestive system
What is the stomach?
A j-shaped organ that both mechanically and chemically digests. It also aborbs select things, such as water, medicine, and alcohol.
What causes stomach ulcers?
When bacteria prevent the stomach from secreting mucus, which exposes the stomach lining to HCl
How does the stomach mechanically digest food?
It twists and turns using longitudinal, circular, and oblique muscles in order to mechanically digest.
How does the stomach chemically digest?
Cells in stomach secrete gastric juice (mixture of enzymes and HCl).
What are the two stomach sphincters?
The one at the entrance is the cardiac/esophogeal sphincter and the one at the exit is the pyloric sphincter.
What is the epiglottis?
The epiglottis in it is a flaplike structure that ensures food does not travel down the trachea.
What enzyme digests protein?
Protein is broken down into polypeptides by an enzyme called pepsin, which is found in the stomach. Pepsin needs an acidic environment. Other proteases, such as trypsin and peptidases also digest them in the small intestine.
What is chyme?
Chyme is the product of both mechanical and chemical digestion (food emerging from the stomach is now chyme).
What is the gallbladder?
It is an accessory organ which stores and concentrates bile received from the liver. It is located under the right lobe of the liver, and sercetes bile into the duodenum, when there are fats.
What is the purpose of bile?
Bile works to break down fats in the intestines, and prevent them from building up and causing blockages.
Explain how the gallbladder secretes bile
It detects undigested fats entering the duodenum. When it detects this presence of lipid, it contracts, releasing bile.
How do gallstones develop?
They develop when large amount of water are absorbed from the bile, and solid materials are left behind. These solid materials can block the bile duct.
Can you remove the gallbladder?
You can, but you will have lots of trouble digesting fats, which will lead to other issues. You may have to take actions, such as specific diet, to regulate these issues.
What is the pancreas?
It is an accessory organ that secretes enzymes awhich help break down food, and bicarbonate ions, which neutralize chyme. It it a finger shaped organ which lies behind the stomach.
What triggers the release of bicarbonate ions from the pancreas?
CCK is a hormone that is released into the blood, and it initiates the release of bicarbonate ions.
What enzymes does the pancreas release?
Lipasses, carbohydrases/amylases, and proteases, malasses
What purpose outside of the digestive system does the pancreas have?
It helps to regulate blood sugar
What is the liver?
It is an accessory organ which has many functions. It’s main function in the digestive system is to synthesize bile, which is a mixture of salts, acids, and water. It makes about 1L/day.
What functions unrelated to the digestive system does the liver have?
It extracts nutrients or toxins from blood, breaks down toxins, stores nutrients, and is involved in metabolism.
What is the small intestine?
The small intestine is an organ that aborbs and chemically digests food. It is separated into the duodenum (beginning), jejunum (middle), illeum (end). It is aided by accessory organs to chemically digest.
What does the small intestine secrete, that digests carbohydrates?
Maltase, which turns maltose into glucose, and amylasses.
What are villi, and what do they do?
Villi are hair-like projections in the small intestine, which increase it’s surface area and therefore enhance absorprion. Each villi is supplied by capillaries and lymph vessels. They aborb glucose (carbohydrates) and amino acids (protein) into the bloodstream. They absorb fats into the lymp vessels (lacteals).
Where does most absorption occur?
In the small intestine. However, water, medicine, and alchohol are absorbed by the stomach. In addition, the large intestine aborbs water and some minerals.
What is the large intestine/colon?
This is an intestine that is twice the diameter of the small intestine, and it acts to aborb water and some minerals. Bacteria that live here produce vitamin B and K to be absorbed.
What is the purpose of cellulose in our digestive system?
As it cannot be digested, it works as a pipe cleaner, effectively prveenting clogs. People who do not eat enough fibers have poor bowel movements, which may lead to colon cancer.
What is the rectum?
An organ which stores waste from the large intestine until excretion.
What is the anus?
A muscle which excretes waste from the rectum.
What is feces?
Feces is 3/4 water, and 1/4 solide matter. The solid material is 30% bacteria, 30% undigested roughage, 20% fat, 15% inorganic matter, 3% protein. A large amount of cellulose is found in feces.
Name the types of digestive enzymes.
Lipasses, Proteases (Pepsin, Trypsin, Peptidases), Amylasses (salivary, pancreatic), Malasses
Name the 6 nutrients
- Carbohydrates
- Proteins
- Lipids
- Water
- Vitamins
- Minerals
What are carbohydrates?
They are nutrients made up of carbon, hydrogen, and oxygen. They are the main source of energy for humans. We cannot synthesize carbohydrates and so they must be consumed.
A healthy diet has at least __% of person’s energy needs fulfilled by carbohydrates.
55%
What is protein?
Proteins are the building blocks of your body (ex. muscles) and perform a wide range of functions. They also provide some energy.
How many amino acids make up proteins, and how many can we make ourselves?
Proteins are made up of 20 different amino acids, but we can only make 11 ourselves. The other 9 must be eaten and are called essential amino acids.
Which has higher concentration of protein: animal or plant?
Animals, which is why vegetarian diets are so difficult.
What are lipids?
Lipids are long-term energy storage, which perform a variety of tasks. They form cell membrane, create insulation, cushion internal organs, and help create sex hormones.
What is water?
Water is a nutrient that has many functions. From cytoplasm, chemical reactions, digestion, excretion, body temperature and more. 55-60% of the body is water, and humans need to drink about 2L of it every day.
What are vitamins?
Vitamins are organic molecules required in small amounts for proper cell functions. There are many different types that are acquired from different sources.
Calcium and phospohorus: Food and function
Foods: Eggs, milk, cheese
Function: Strengthens bone and teeth
Potassium and magnesium: Food and function
Foods: Fruits and vegetable
Function: Assists in muscle contraction
Sodium and chloride: Food and function
Foods: Salty foods and table salt
Function: Assists in digestion, muscle, nerve function
Vitamin K: Food and function
Foods: Green vegetable, tomatoes
Function: Helps with blood clotting
Vitamin E: Food and function
Foods: Milk, butter, leafy greens, eggs
Function: Needed for proper function of body’s chemical reactions
Vitamin D: Food and function
Foods: Liver, milk, made by your skin
Function: Aids in proper growth of teeth and bones
Vitamin C: Food and function
Foods: Oranges. grapefruits, lemons, limes, tomatoes, spinach
Function: Needed for growth, good for teeth and gums
VItamin B (12 types): Food and function
Foods: Green and yellowish vegetable, whole grain
Function: Aids in nerve function and energy release carbohydrates
VItamin A: Food and function
Foods: Carrots, spinach, beets, yam
Function: Aids in proper growth and night vision
Iron: Food and function
Foods: Liver, meats, eggs, vegetable
Function: Helps red blood cells carry oxygen molecules
