Flashcards in Digestive System Deck (78):
How much of our bodies are composed of water?
What percent of water makes up the composition of certain tissues and organs
List four functions of water
1) dilutes waste substances and transports them out of bodies
2) Acts as an important dissolving agent or solvent, so that substances can be transported within bodies and through cell membranes
3) functions as a lubricant (saliva, mucous)
4) acts as a temperature regulator (as perspiration evaporates from the skin)
List four ways that water can enter the body.
1) absorbing it
2) drinking it
3) entering bodies from the food of a plant or animal
4) dehydration synthesis
What is ingestion?
The process of taking in nutrients into a body.
What is the first stage of digestion?
Physical or Mechanical
What happens during the first stage of digestion?
-chewing or grinding of food is done to make a smaller form
What do the churning and grinding actions of the stomach or gizzard do?
Help breakdown further (phase 1)
What is phase two of digestion?
What is the main component of chemical breakdown (phase two)?
What are hormones used for in the second stage of digestion?
To stimulate the enzyme secreting glands to help in digestion.
What are the three main functions of the human digestive system?
1) Injest food
2) break food down so nutrients can be ansorbed
3) eliminate what cannot be digested
What do we digest?
What happens when we digest proteins?
Amino acids are absorbed through the what and carried into the what?
-Proteins are broken down into component amino acids in the stomach and small intestines
-Amino acids absorbed into blood stream through small intestine and carried to various body cells
What happens when we digest carbs?
Where are simple carbs absorbed?
-Complex carbs are broken down into simple carbs in the stomach, small intestine, and mouth
-Simple carbs are absorbed in the small intestine and circulated throughout the body by the blood
What happens when we digest lipids?
Where are lipids digested?
Fatty acids are absorbed in the what?
Fatty acids are broken down where?
-Digested in the small intestine into fatty acids and glycerol
-Fatty acids are absorbed in the small intestine and circulated in the blood throughout the body.
-Fatty acids are broken down in the liver to acetic acid
What is acetic acid?
Source of fuel for liver-produces acetone as byproduct.
What is acetic acid?
Acitic acid is a source of fuel for liver. Produces acetone as byproduct.
What parts of the mouth begin mechanical digestion? How do they do this?
-The tongue and the teeth
-They crush the food into smaller pieces
What glands supply saliva and mucous? Where are they located? What is the purpose of the saliva and mucous?
-The salivary glands and mucous glands
-They are located along the cheeks
-The mucous and saliva helps moisten and break up food
What enzyme does saliva have? What does this enzyme begin?
-Begins the chemical digestion of starches
What takes place after the food is broken up?
What happens once food is in the esophagus?
-Muscular movements called peristalsis moves the bolus downward through the cardioesopjageal sphincter into the stomach.
What is stage one of digestion?
What is stage two of digestion?
What happens in the stomach?
-Both physical and chemical digestion occur
How many muscle layers make up the stomach walls?
three muscle layer
What are these muscles called?
What do the muslces that line the stomach wall do?
Cause rhythmic contractions along the stomach's length resulting in the mixing of food, mucous, acid, and enzymes.
What is the pH in the stomach?
What do the glands in the stomach do?
Secret chemicals called gastric juices due to neural and hormonal factors.
What does hydrochloric acid do? Hint: 4 things
Helps the enzymes to:
1) Dissolve minerals
2) Kill bacteria
3) Regulate the pyloric valve
4) Stops the action of amylase that began in the mouth
What does the enzyme pepsin do?
Pepsin breaks down proteins into short chain amino acids.
What does the enzyme gastrin do?
Gastrin acts on the fats and oils.
What does mucous act as?
Mucous acts as a lubricant and as a protector of the stomach wall from the actions of al acids and enzymes. Without mucous, acid would eat through the stomach wall.
Is digestion one continuous cycle, or does it pause?
It is one continuous cycle.
How many litres is the stomach?
How long may food remain in the stomach?
2 to 3 hours
What happens when food has reached the acidity level?
It leaves the stomach through the pyloric sphincter and enters the small intestine.
What is food called once it reaches the small intestine?
What is stage three of digestion not possible without?
What is the longest part of the digestive tract? How long is it?
-The small intestine
-7m in length. 2.5 cm in diameter
What did mechanical digestion push further through the small intestine. What was it due to?
What does the acidity of the chyme stimulate? Where does this happen?
-the secretion of 2 hormones
-glands in the first part of the small intestine or duodendum
What does one of the hormones produced by glands in the first part of the smal intestine act upon?
The adjacent pancreas causing it to produce pancreatic juice.
Trace the path of pancreatic juice.
-makes its way from pancreas through a duct that joins with a bile duct from the liver.
What do the two ducts form?
-the two ducts form one common duct that enters the duodenum a short distance below the pyloric sphincter
What does the pancrease secrete? What do these hormones do?
-The hormones insulin and glucagon
-They regulate the amount of sugar in the blood
What happens when glucose levels are high?
Insulin produced (causes insulin to be stored as glycogen).
What happens when glucose levels are low?
When glucose elvels are low, glucagon is released (causes glycogen to be converted back into glucose).
What does the OTHER hormone in the duodenum affect?
What does the liver do?
The liver produces bile that is stored in the gallbladder.
What is bile made up of? Hint: 2 things.
Explain what each are.
Bile is made up of bile salts that cause fats to emulsify or break up into find droplets. Bile is also made up of bile pigments, mainly red blood cells and hemoglobin, which is what gives the brownish colour to solid wastes or feces that are eliminated from the large intestine.
What does the liver convert?
Excess monosaccharides into glycogen if there is sufficient amounts of glucose.
Wht does the liver break down?
Excess amino acids and takes the excess nitrogen molecules and converts them to waste urea.
What does the liver filter? What does it do to them
-drugs and alcohol
What is the liver the final break down of?
The liver is the final breakdown of fats.
What completes chemical digestion?
The pancreatic enzymes along with additional enzymes produced by the intestines.
In small forms ______ are capable of being absorbed into the blood to be transported to other body areas?
Where does the greatest amount of absorbtion occur?
The small intestine.
What are the three parts of the small intestine. Briefly describe.
1) Duodenum (area where most chemical digestion occurs)
2) Jejunum (absorbtion of nutrients)
3) Ileum (absorbtion of nutrients)
What does the small intestine have that increase the absorptiove area?
folds and twists
What are the finger like projections called that increase the total absorptive area of the small intestine?
What passes through the epithelial cells of the villi? Where do they pass into and by what?
-Glucose and other monosaccharides, amino acids and minerals
-Into the blood capillaries
-Diffusion and/or active transport
What happens to the materials that cannot be digested or absorbed in the small intestine?
Thye move onto the large intestine (semi liquid).
Where do the final stages of digestion take place?
The large intestine.
How long is the large intestine?
1.5 m long. 6.5 cm in diameter
What makes up the large intestine?
How many hours after you have eaten do the final stages of digestion take place?
Do small or large amounts of digestion occur in the large intestien?
What is the main role of the large intestine?
The main role of the large intestine is the reabsorption of water.
How has water entered the system up until the point digestion reaches the large intestion? Have these been large amounts or small amounts of water?
Why does the large intestine reabsorb this water?
So you body does not lose it and become dehydrated.
How long does chyme normally remain in the large intestine?
18 hours-2 days
When chyme is in the large intestine, what is it converted from to?
It is converted from a watery consitency to the normally solid fecal matter.
Where do solid wastes accumulate?
The final portion of the large intestine.
How many spincters does the rectum have. What are they involved in?
-Two sphincters, one at the beginning and one at the end.
-They are involved in teh final elimination of wastes.