Studied by 0 peopleWhat do cells need to carry out their functions?
energy
where do energy come from?
nutrients from our food
how are nutrients distributed throughout the body
The digestive system absorbs the nutrients and the circulatory system delivers the nutrients to all the cells of the body.
what is a nutrient
Any substance that has a useful function when taken up by the body cells
what are the 5 types of nutrients
Carbohydrates, protein, fats, vitamins + minerals, and water
What is a macronutrient?
needed in large amounts
what is a micronutrient?
needed in small amounts
what are the macro nutrients
carbs, fats, proteins
what are the micronutrients
vitamins and minerals
what are the organic nutrients
carbohydrates, fats, proteins, vitamins
what are the inorganic nutrients
minerals
what elements are carbs made out of
carbon, hydrogen, oxygen
what are carbs used for
short-term energy storage
what are monomers and what are some examples
Simplest molecules are MONOMERS called MONOSACCHARIDES (eg. glucose, fructose, galactose)
what are complex carbs known as and what are they composed of and provide some examples
More complex carbohydrates composed of 2 monomers are DISACCHARIDES (eg. maltose, sucrose, lactose) and POLYSACCHARIDES are composed of many monomers (eg. starch, glycogen, cellulose)
what elements are in fats
long chains of carbon, hydrogen, oxygen
what is the function of fats
Used for long-term energy storage + many other functions
do fat provide more or less energy than carbs
Provide more energy than carbohydrates
what is the basic structure of a fat
Basic structure is a 3-carbon glycerol molecule attached to 3 fatty acids (long C-H chains)
what is unsaturated fat
if fatty acid chain contains double bonds. These fats are liquid at rm. temp.
is unsaturated the good fat or bad fat and what are some examples
good fat, vegetable oil
what is saturated fat
if fatty acid chain contains no double bonds. These fats are solid at rm. temp.
is saturated the good fat or bad fat and what are some examples
bad fat, butter
what are some esential fatty acids
(eg. linoleic, linolenic, arachide)
What elements make up proteins?
carbon, hydrogen, oxygen, nitrogen
funtions of proteins
many functions
what are protein polymers made out of
POLYMERS made from AMINO ACID monomers
how many amino acid monomers are there
20
what are the 20 amino acid monomers held togther by and what do they form
20 amino acid monomers that are held together by PEPTIDE BONDS in different combinations to form POLYPEPTIDE chains
How many amino acids are essential?
8
what elements are vitamins made from
C, H, O, N + other elements
what do vitamins act as
Most act as coenzymes
what are the 2 types of vitamins and provide examples of both
"Fat Soluble" (A, D, E, K) 2. "Water Soluble" (B1, B2, B12, C)
what element make up minerals
inorganic elements
what are examples of mineral s
Ca, Fe, Na, K etc.
what are the 4 processes of the digestive system
ingestion, digestion, absorption, egestion
what is ingestion
taking food into the mouth
what is digestion
Breaking down food into small soluble molecules
what is absorption
digested food passes into the blood.
what is egestion
Elimination of waste undigested food.
What is a polymer?
long chain of monomers
What is a monomer?
single unit
what happens to the food you eat
Food is made of complex insoluble macro-molecules. (polymers)
Has to be broken down into small soluble micro-molecules like glucose, amino acids, fatty acids and glycerol to be used by the body. (monomers)
2 methods to breakdown food
mechanical and chemical
what is used for mechanical digestion
Teeth Muscular contractions Bile
what is used for chemical digestion
Enzymes
What is the alimentary canal?
A long tube starting at the mouth and ending at the anus
the digestive system consists of ..
The Alimentary Canal
Accessory Digestive Organs
what does the alimentry canal include
Includes Oral Cavity, pharynx, esophagus, stomach, small intestine, large intestine and anus
what are the acessory organs
Liver Pancreas Gall bladder Salivary glands
what in the chemical and mechanical digestion that takes place in the mouth
chewing - mechanical saliva - chemical
what in the chemical and mechanical digestion that takes place in the stomach
stomach churning - physical stomach acid - chemical
what is the mechanical part of the oral cavity
the mouth
Teeth break food into smaller pieces that increases the surface area for digestion
Saliva creates a basic pH of about 8 & moistens food allowing soluble chemicals to dissolve.
what is the chemical digestion of the oral cavity
Salivary glands produce the enzyme AMYLASE - this begins the breakdown of STARCH
Chewed food is mixed with saliva from 3 pairs of salivary glands, the food is now called a BOLUS (food ball)
what does amylase break down
starches
what is the process. of swallowing also called?
deglutition
how many muscles does swallowing require?
over 20 muscles of the throat mouth and esophogus
how many phases does swallowing consist of?
3
what are the three phases pf swallowing?
oral or buccal
pharyngeal
esophageal phase
What is a voluntary muscle?
muscle you can control
What is involuntary muscle?
A muscle that is not under conscious control.
Is oral phase of swallowing voluntary or involuntary.
voluntary
What happens in the buccal phase?
the food is moistened by the saliva
a food bolus is formed
and the tongue pushes it back to the throat or the pharynx
what happens in the pharyngeal phase?
starts with the stimulation of tactile receptors in the orophrynx by the food bolos.
the swallow reflex is initiated and is under unvoluntary neuromuscular control. this is done to make sure food enters the esophogus.
the tongue blocks the oral cavity to prevent food from going back into the mouth. the soft palate prevents entry to the nasal cavity. the vocal cords close to prevent entry to the lungs.
the larynx is pulled up with the epiglottis flipping over covering the entry to the trachea.
the upper esophageal sphincter opens allowing passage to the esophagus
what happens in the esophageal phase?
•food is propelled down the esophagus by peristalsis
the larenx moves back to original position
What is peristalsis?
controlled wave like muscle contractions
How does food enter the stomach?
The lower esophegeal/cardiac sphincter
What is a sphincter?
A circular muscle that constricts or dilates to regulate the passage of materials through an opening
what are the 4 stpes of the mechanical digestion in the stomach
Food enters the stomach through a valve known as the CARDIAC SPHINCTER or lower esophageal sphincter
The stomach churns the food like a blender using muscles called RUGAE
Food is liquefied (Mechanical Digestion) and now is known as CHYME
Food stays in the stomach for several hours
what is the importance of the sphincters
prevents acid from entering esophagus
Chemical digestion in the stomach
stomach acid
what does gastric acid contain
Gastric juice contains
Hydrochloric acid:
Mucus:
Pepsinogen:
whatdoes hcl do
kills bacteria & mechanical digestion
what does the mucus do
protects stomach lining
what is pepsinogen
inactive protein enzyme
What activates pepsinogen? what does it activtae into?
hci activates pepsinogen into pepsin
what does the pepsin do
break down protein into small polypeptides
what occurs in the small intestine
The small intestine is where final digestion and absorption occur.
how is the small intestine organized in our body
Coiled tube(convoluted) over 3 meters long. Coils and folding plus villi give this 3m tube the surface area of a 500-600m long tube.
what are the 3 areas of the small intestine?
Duodenum: Jejunum: Ileum:
what is the function od the duodenum
chyme enters from the stomach & gets bathed in enzymes
what is the function for the jejunum
site of MOST absorption
what is the function of the illeum
some absorption. Connects with Large intestine
why does the small intestine have a increased surface area
Has an increased surface area due to fingerlike projections called VILLI
what is each villi covered with
microvilli
what does the small intestine produce
Produces enzymes that complete the digestion of carbohydrates, proteins and fats.
how many cells make up the villi
many cells
Where does absorption occur?
ABSORPTION occurs primarily in the Jejunum but also the ileum. Food has been broken down into particles small enough to pass into the small intestine.
What is a thin epithelium?
the skin of each villus is only one cell thichk, this allows absorption to happen very fast
what is a lacteal
the lacteal absorbs fatty acids and glycerol
what is good blood supply
the blood capillaries absorb sinple sugars and amino acids
how long is our small intestine
7 meters
why does the small intestine slosh around everywhere
The mesentery is a fold of membrane that attaches the intestine to the abdominal wall and holds it in place.
what is an acessory organ
The accessory organs aid in digestion but are not a part of the G.I tract and are made up of the
what are the 4 accessory organs
Salivary glands Liver Pancreas Gall bladder
what does the liver, pancreas, and gall bladder
secrete enzymes into the duodenum (SI)
what does the pancreas produce
digestive juices enzymes bicarbonate salts insulin
where are digestive juices released from
pancreatic duct
what type of enzymes do the pancreas produce
enzymes that digest carbohydrates, proteins and fats.
what is the point of bicarbonate salts
to neutralize the stomach acid.
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