the digestive system Flashcards
what are carbohydrates and where are they in the energy chain?
carbohydrates are first in the energy chain, they contain CH2O and they are the building blocks for cell membranes
what type of energy do carbohydrates provide?
carbohydrates provide short and long term energy.
why are carbohydrates first in the energy chain?
they are very small and easy to digest.
what happens if carbohydrates are not used?
they are stored as glycogen.
what is a monosaccharide?
simple sugars made up of 3-7 carbon atoms.
what are examples of monosaccharides?
glucose and fructose.
what is a disaccharide?
disaccharides are made up of two monosaccharides, hence it’s “di-“ prefix.
what are some examples of disaccharides?
sucrose, maltose, and lactose.
what happens when disaccharides are not turned into monosaccharides?
it could inflict pain, such as a lactose intolerant person.
what is a polysaccharide?
polysaccharides are carbohydrates made up of many monosaccharides.
what are some examples of polysaccharides?
glycogen and starch ( cellulose makes up cell walls in plants )
what is the conversion rate of grams of carbohydrates to calories?
every one gram of carbohydrates equates to four calories.
what are carbohydrates commonly seen as?
plants, bread, and pasta.
what are lipids and where are they in the energy chain?
lipids are insoluble/hydrophobic monomers and are second in the energy chain.
what is the structure of a lipid?
they are a glycerol molecule attached to a fatty acid chain.
what are the key functions of lipids?
- storage for energy molecules
- helping to absorb vitamins (A, D, E, and K)
- insulating and cushioning the body
- building cell membranes
why are lipids second in the energy chain?
they are second in the energy chain because they are hard to break down due to being hydrophobic, thus they are primarily an energy reserve.
what is the conversion rate of grams of lipids to calories?
every one gram of lipids equate to nine calories.
what are lipids commonly seen as?
fats, waxes, oils, steroids, and cheese.
what are proteins?
proteins are composed of small sub-units called amino acids ( they are monomers of protein ).
how are proteins bonded?
they are joined together by peptide bonds. peptide bonds are formed by two hydrogen atoms and one oxygen atom, creating a water molecule and forming a bond between a carbon and nitrogen atom.
what are peptide chains called?
polypeptides.
what are the key functions of protein?
- enzyme structure, immunity, and transportation
- structural component of cells in the body
- acts as antibodies
- proteins are not often used as energy due to its high importance in the body
what is the conversion rate of grams of proteins to calories?
every one gram of protein equate to four calories.
what are proteins commonly seen as?
meat, insulin, hemoglobin, collagen, and antibodies.
polysaccharide + water + enzyme = ?
polysaccharide + water + carbohydrase = monosaccharide molecule
lipid + water + enzyme = ?
lipid + water + lipase = glycerol molecules + fatty acid molecules
protein + water + enzyme = ?
protein + water + protease = amino acid molecules
nucleic acid + water + enzyme = ?
nucleic acid + water + nuclease = nucleotide
what are enzymes made of?
proteins.
what do enzymes do and how do they work?
enzymes break down large macromolecules into small molecules through a process called hydrolysis.
what are nucleic acids?
nucleic acids are often seen in genetic information.
what are the key functions of nucleic acids?
- directs growth and development of all organisms using a chemical code
- used for genetic information
- contributes to direct growth
are nucleic acids used for energy? why or why not?
no, they are not used for energy due to their importance in functions, such as: genetic code and growth.
what are nucleic acids seen as?
DNA and RNA ( the building blocks of life ).
what percentage does water make up of your body?
60-70% of the human body is water.
what are the key functions of water?
- regulation of different ions
- transports dissolved nutrients into cells that line the small intestine
- flushes toxins from cells and lubricates tissues and joints
- forms essential body fluids ( blood and mucus )
- regulates body temperature
- eliminates waste materials ( through urine and sweat ) - 1.5 litres of urine per day and 1 liter through perspiration
how does digestion begin in the mouth?
mechanical digestion - food is masticated by the teeth and turned into bolus by the tongue.
chemical digestion - saliva aids the chemical breakdown of carbohydrates by the amylase enzyme.
what is saliva?
a watery secretion from the salivary glands that are released in the mouth and begin the digestive process.
what does saliva do?
- contains amylase enzymes which break down starches ( complex carbohydrates )
- lubricates food for swallowing
- dissolves particles and helps to taste the food
- dissolved particles penetrate the cells of tastebuds on the tongue and cheek
what are salivary glands?
sublingual glands that release saliva into the mouth through smaller ducts.
what is the esophagus?
a muscular tube that food passes through from the mouth to the stomach.
how does the esophagus pass food through it?
the esophagus is composed of smooth muscle and the bolus activates peristalsis. peristalsis is an involuntary rhythmic muscle contraction that moves it down the esophagus and into the stomach.
what are esophagus glands?
the lining of the esophagus which produce mucus.
why are esophagus glands a thing?
it is to keep the passage moist, helping the swallowing process.
what are sphincters?
a regulator of movement for food in and out of the stomach.
what is the difference between the cardiac and pyloric sphincter?
cardiac sphincter - relaxation allows food to enter the stomach.
pyloric sphincter - allows food to exit the stomach and enter the duodenum.
how does mechanical digestion occur in the stomach?
rugae - the stomach lining. it allows the stomach walls to mechanically churn and fold for reduction or unfold for expansion when full
chyme - a thick liquid produced in the stomach made of digested food with gastric juices
three layers of muscle fibres - they help to contract, relax, and churn to mechanically break down pieces of food
peristalsis - aids mechanical digestion by mixing gastric juices with bolus
how does chemical digestion occur in the stomach?
gastric juices - secreted by glands in the stomach, is a mixture of HCl, salts, enzymes, water, and mucus
alkaline mucus - protects the stomach lining from being digested by gastric juices
what are some qualities of HCl?
- kills harmful substances
- pH ranges from 2.0-3.0
- converts pepsinogen ( protein digesting enzyme ) to its active form: pepsin
what are some characteristics of the stomach?
- 1.5 liter capacity
- j shaped
- located in the abdominal cavity
what is villi?
finger-like projections lining the surface of the small intestine, these increase the surface area and improve the absorption of nutrients.
what are the three divisions of the small intestine’s jobs (in order)?
duodenum - to raise pH
jejunum - to break down
ileum - to absorb
list the main characteristics of the duodenum.
- to raise pH
- it is the first 25-30 cms of the small intestine
- it is not mucus lined, and is unable to handle stomach acids
- liver and pancreatic secretions bring pH up ( 5-6 )
list the main characteristics of the jejunum.
- to break down
- the following 2.5 meters
- contains lots of folds on the inner wall
- breaks down remaining proteins and carbohydrates
- pH is between 7 and 9
list the main characteristics of the jejunum.
- to absorb
- the remaining 3 meters of the small intestine
- contains fewer and smaller villi than the duodenum or jejunum
- its function is to absorb nutrients and push remaining, undigested material into the large intestine
what does the large intestine/colon do?
- absorbs water
- 90% of water is absorbed back into the blood
- volume of indigestible food is mostly reduced by about 2/3
what does the large intestine/colon consist of?
- appendix
- ascending colon
- transverse colon
- descending colon
- rectum
what are the functions of an enzyme governed by?
- enzymes have one function: to break down their macromolecule
- enzymes need a specific temperature ( 30º to 40º ) and pH
- if the enzymes do not meet these standards, they often are ineffective or disabled
what is the role of the pancreas?
the pancreas increases the pH to a more neutral level as it is a very common base.
what does pancreatic fluid contain?
- secretes 1L of pancreatic fluid into the duodenum
- enzymes to digest carbohydrates, lipids, and proteins
- bicarbonate which helps to regulate enzyme functions and the pH in the duodenum
what does the liver do in the body?
- digests fat and filter things that shouldn’t be in the body
- secretes bile ( a greenish yellow fluid which breaks down fats )
- green colour from destruction of old red blood cells ( RBCs )
what does the gall bladder do?
- stores bile and is essential in the digestion of fats
- stores bile that is created in the liver
what are digestive enzymes? how and where do they work?
digestive enzymes help break down food into forms that can be absorbed and used by the body, they are normally found / secreted by:
- in the mouth ( saliva )
- by the stomach
- released into small intestines from the liver and pancreas
what does amylase do? and where is it secreted from?
- breaks down starches
- is secreted in the saliva and pancreatic juices
what does protease do? and where is it secreted from?
- breaks down protein
- is secreted by the pancreas
what does lipase do? and where is it secreted from?
- breaks down fats ( lipids )
- is secreted by the pancreas
what does pepsin do? and where is it secreted from?
- pepsin breaks down protein
- released in the stomach
what does mycozyme do? and where is it secreted from?
- breaks down starches
- secreted in the stomach
