Digestive System Flashcards
What chemical elements are present in carbohydrates?
C,H,O
What do carbohydrates serve as?
A readily available energy source
What’s one way to identify simple carbohydrates?
Many end in ose (glucose, sucrose, maltose, lactose)
What are monosaccharides?
Building blocks for other types of carbohydrates
What is the general chemical formula for most monosaccharides
Some multiple of CH2O (glucose - C6 H12 06)
What is the shape of monosaccharides?
Open chains or in rings
What are isomers?
When they have the same chemical formula but are structurally different - many monosaccharides are isomers
What are disaccharides
Consists of two monosaccharides joined together
What is ingestion
The taking in of nutrients
What is digestions
The breakdown of organic molecules into smaller complexes
What is absorption
The transport of digested nutrients to the tissues of the body
What is egestion
The removal of materials from the body that the body cannot digest
What is physical digestion/mechanical digestion
It involves chewing, mixing with saliva, emulsifying, squeezing and churning. The purpose is to increase surface area to make chemical digestion more efficient
What is chemical digestion
Involves the breaking of large molecules by enzymes using the process of hydrolysis
What are examples of foods containing simple carbohydrates?
Fruit, sugar cane, sweet potatoes, yams
How are monomers linked together?
By the removal of a water molecule in a
process called dehydration synthesis
What are complex carbohydrates made up of?
A few hundred to a few thousand monosaccharides linked together
What are complex carbohydrates used as?
Storage material in plants and animals and as structural components such as cell walls in plants
What is a starch
The storage polysaccharide of plants
What are starchs made up of?
Only glucose
What are the two different types of structure in starches
Amylase and amylopectin
What is amylase
helical and straight line configuration
What is amylopectin?
Branched
What are examples of starches?
Potatoes, grains, corn, rice, pasta
How do plants store glucose from photosynthesis?
As starch and withdraw starch as needed
What is glycogen?
The storage polysaccharide of animals
Which is more branched? Amylopectin in plants or glycogen?
Glycogen (animals)
Where is glycogen stored?
In the liver and muscle cells
What is the most abundant organic compound on the earth’s surface?
Cellulose
What does cellulose do?
Encloses plant cells
What is cellulose made of?
Glucose (like starch) but has a different bonding arrangement
What is the structure of cellulose?
A linear molecule ideal for forming “strands” in a “rope”
Can humans digest cellulose for energy?
No but it is useful as dietary fibre (adds bulk to the formation of a stool)
Where is chitin found?
exoskeletons of insects, spiders and crustaceans
What do fungi use instead of cellulose for their cell walls?
Chitin
How can you identify the presence of reducing sugars?
The Benedict’s test
Are all monosaccharides reducing sugars?
Yes
Are all disaccharides reducing sugars?
Only some
Are polysaccharides reducing sugars?
No
What happens when the Benedict’s reagent (light blue) is mixed with a reducing sugar and heats up?
Changes to a yellow green or brick red colour
What does the iodine test identify?
Starches
Where does ingestion of food occur and digestion begins?
The mouth
How is saliva produced?
Salivary glands
What is the function of saliva?
Moisten food, make it easier to swallow and also begin the chemical digestion of carbohydrates specifically starch’s
What enzyme begins the chemical digestion of starch?
Salivary amylase - breaks into disaccharides
What type of digestion occurs to different macros in the mouth?
Only physical digestion of lipids and proteins occur in the mouth
Only starch (amylose) begins to be chemically digested
Explain the process of swallowing
The bolus of food is pushed against the roof of the mouth (the soft palate) by the tongue. As it moves down the pharynx
it pushes down on the epiglottis so that the trachea is covered and food does not enter it.
What does the esophagus connect
Connects the mouth to the stomach
Is swallowing voluntary?
Yes but movement of food starting at the esophagus and continuing through the digestive tract is involuntary
What is ulcers??
when the layer of mucus that protects the lining of stomach from the acids erodes
What are the two inflammatory bowel diseases?
Crohns disease and colitis
What is Crohn’s disease?
Inflammatory bowel disease that affects anywhere in digestive track, usually small intestine, causes intestines to empty frequently
What is colitis?
Inflammatory and ulceration of lining of colon, any refers to linning where as chrohns affects entire thickness of colon
What is hepatitis?
Inflammation of the liver
What two types of hepatitis’s have vaccines
Type a and b
How can an individual contract hepatitis A
Contaminated water
How can an individual contract hepatitis B
Sexual contact
How can a person contract hepatitis C
Contact with infected blood (no vaccines)
What are three disorders of the accessory organs?
Hepatitis, cirrhosis, and gallstones
What is cirrhosis?
chronic disease of liver; when scar tissue replaces healthy liver tissue, preventing proper function, chronic alcoholism + hepatitis c can cause cirrhosis
Yay!
Your doing great
What are two types of psychological digestive diseases?
Anorexia and bulimia
Mobid fear of gaining weight digestive tract can stop
What is the main function of the small intestine?
complete digestion of macromolecules and absorb subunits
What happens in the small intestines (what type of digestion)
Some physical digestion in a process called segmentation
What is the duodenum?
First 25cm of the small intestine
How does the esophagus move food?
Peristalsis, wave like contractions of the smooth muscle that lines the entire digestive tract until it exits the body, they’re so strong that you could eat food standing on your head and it would still reach your stomach
How does food enter the stomach?
By the relaxation of the esophagus (cardiac sphincter) located at the top of the stomach
What is a bolus
Mound of food
What type of digestion occur in the stomach
Both chemical and physical
What does physical digestion involve in the stomach? (M)
Churning of food, stomach has three layers of muscles that mechanically break down food
How does chemical digestion occur in the stomach?
A substance released from the cells lining the stomach called gastric juice
Where does carbohydrate digestion stop?
In the stomach
What is gastric juice composed of?
Water, mucus, salt, hydrochloric acid, and pepsin
What is pepsin?
An enzyme that digests proteins
What pH level does hydrochloric acid make the stomach
Between 1-3
What is the function of hydrochloric acid?
Soften proteins a little bit
Asked to activate the enzyme pepsin, so it can digest proteins into smaller peptides
kills most bacteria that are ingested along with food, or in the mucus produced by the respiratory system
What does pepsin do?
Digests proteins into shorter segments of polypeptides and it’s in active form. It is called pepsinogen and it’s activated form into pepsin. It’s active form by hydrochloric acid.
What is pepsinogens active form and how is it activated?
Pepsin and activated by hydrochloric acid
Why is pepsinogen released in its inactive form?
Because the stomach itself is made of protein so pepsin would digest the stomach if it’s activity was not carefully regulated
How does the stomach protect itself from self digestion?
Gastric juice is mostly secreted when there is food in the stomach.
• Stomach cells secrete mucus that prevents gastric juice from doing too much damage.
•Pepsin is secreted in an inactive
form.
How often is the stomach lining regenerated?
Every 3 days
Where does food exit the stomach from and what is it’s substance called?
Through the pyloric sphincter into the small intestine and it’s called chyme at this point
Does absorption occur in the stomach?
Limited because food hasn’t been digested so it can’t be absorbed into the stomachs surrounding blood vessels, however small molecules such as water, some salt ions and alcohol are absorbed through the stomach wall into the blood capillaries
What is the longest structure in the digestive system?
The small intestine
What three segments are the small intestine divided into?
Duodenum, ilium and jejunum
What is chyme neutralized with when it enter the duodenum?
Bicarbonate (HCO3)
What does the liver produce and what does it do?
Liver produces bile which emulsifies fats (breaks them into smaller droplets to increase surface area)
Is the inner surface of the small intestine smooth?
No, rather heavily folded to increase surface area
What are the folds in the small intestine covered with?
Finger like projections called villi (pl. villus sing) and the surface area of the villi are covered with villus. These give the small intestine a surface area that is 600 times larger than it would be if it were a smooth cylinder
How are monosaccharides and amino acids absorbed?
Directly into the capillary network by active transport
What happens once monosaccharides and amino acids are absorbed into the capillary network?
Go to the liver, and from there they’re sent to the rest of the body by blood plasma
How are lipids absorbed?
The lacteal which is part of the lymphatic system
What happens when chyme enters duodenum?
The pancreas secretes pancreatic juice that contains enzymes as well as bicarbonate ion to neutralize the acidic chyme
What three enzymes (that you need to know) are produced by the pancreas
Pancreatic amylase, pancreatic lipase and proteases, trypsin and chymotrypsin
What substances are digested by pancreatic amylase and what is produced?
Starch (plants) glycogen (animals)
Disaccharides/monosaccharides
What substances are digested by pancreatic lipase and what is the product?
Lipids
Glycerol and fatty acids
What substances are digested by proteases (enzyme that breaks down proteins), trypsin and chymotrypsin and what are the products?
Small polypeptides
Smaller peptides
What does the liver produce as a by-product of RBC breakdown? I
Bile
What does the liver do?
Maintains normal nutrient levels in the blood
What vein carries blood from the intestine, laden with nutrients to the liver?
The portal vein
What will the liver store excess glucose from the blood as of its very high?
Glycogen or adding glycogen when blood levels are low in response to insulin and glucagon
What are the other functions of the liver (5)
Production of urea (from the breakdown of amino acids)
Production of plasma proteins
Processing cholesterol levels
Detoxification of alcohol and other poisons
Indefinite storageof foreign substances it cannot destory
Storage and distribution of vitamins A,B12,D and iron
What is the purpose of the gall bladder?
Bile is continuously produced by the liver then goes to the gall bladder for storage until needed
When are gallstones formed?
When cholesterol precipitates out of the bile and the crystals grow. Heredity, obesity, alcohol intake are all factors in gallstone formation however can be treated with medication, ultrasound shock or at last resort surgery
