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The three lipases responsible for lipid digestion are lingual lipase, gastric lipase, and pancreatic lipase    . However, because the pancreas is the only consequential source of lipase, virtually all lipid digestion occurs in the small intestine. Pancreatic lipase breaks down each triglyceride into two free fatty acids and a monoglyceride. The fatty acids include both short-chain (less than 10 to 12 carbons) and long-chain fatty acids.

Nucleic acid digestion

The nucleic acids DNA and RNA are found in most of the foods you eat. Two types of pancreatic nuclease    are responsible for their digestion: deoxyribonuclease    , which digests DNA, and ribonuclease    , which digests RNA. The nucleotides produced by this digestion are further broken down by two intestinal brush border enzymes ( nucleosidase    and phosphatase    ) into pentoses, phosphates, and nitrogenous bases, which can be absorbed through the alimentary canal wall. The large food molecules that must be broken down into subunits are summarized [link]

Absorbable Food Substances
Source Substance
Carbohydrates Monosaccharides: glucose, galactose, and fructose
Proteins Single amino acids, dipeptides, and tripeptides
Triglycerides Monoacylglycerides, glycerol, and free fatty acids
Nucleic acids Pentose sugars, phosphates, and nitrogenous bases

Absorption

The mechanical and digestive processes have one goal: to convert food into molecules small enough to be absorbed by the epithelial cells of the intestinal villi. The absorptive capacity of the alimentary canal is almost endless. Each day, the alimentary canal processes up to 10 liters of food, liquids, and GI secretions, yet less than one liter enters the large intestine. Almost all ingested food, 80 percent of electrolytes, and 90 percent of water are absorbed in the small intestine. Although the entire small intestine is involved in the absorption of water and lipids, most absorption of carbohydrates and proteins occurs in the jejunum. Notably, bile salts and vitamin B 12 are absorbed in the terminal ileum. By the time chyme passes from the ileum into the large intestine, it is essentially indigestible food residue (mainly plant fibers like cellulose), some water, and millions of bacteria ( [link] ).

Digestive secretions and absorption of water

This image shows the human digestive system. Next to each organ, a text callout identifies how water and digestive secretions such as saliva and bile are processed.
Absorption is a complex process, in which nutrients from digested food are harvested.

Absorption can occur through five mechanisms: (1) active transport, (2) passive diffusion, (3) facilitated diffusion, (4) co-transport (or secondary active transport), and (5) endocytosis. As you will recall from Chapter 3, active transport refers to the movement of a substance across a cell membrane going from an area of lower concentration to an area of higher concentration (up the concentration gradient). In this type of transport, proteins within the cell membrane act as “pumps,” using cellular energy (ATP) to move the substance. Passive diffusion refers to the movement of substances from an area of higher concentration to an area of lower concentration, while facilitated diffusion refers to the movement of substances from an area of higher to an area of lower concentration using a carrier protein in the cell membrane. Co-transport uses the movement of one molecule through the membrane from higher to lower concentration to power the movement of another from lower to higher. Finally, endocytosis is a transportation process in which the cell membrane engulfs material. It requires energy, generally in the form of ATP.

Questions & Answers

how does it work?
Uriah Reply
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LOUIS
I want to know the fertilization process in human
Nana Reply
Which plane divides the body into right and left parts
Kaeze
sagittal plane
Irvin
Thank you
Kaeze
Homestatic regulations usually involves a (n) _ that detects a particular stimulus, and a(n) _that respond to the stimulus by communicating with a (n) _whose activity has an effect on the same stimulus.
Kaeze
A cell is producing proteins to be transported out of that cell. They will be processed on ribosomes that are
Kaeze
what are diseases in the bood
Azoyenime Reply
Haemophilia
Aliyu
right hypochondriac rision how meain word
Ganesh Reply
Diabetes insipidus or diabetes mellitus would most likely be indicated by ________.
Ganesh
oral cavity how miean
Ganesh Reply
oral cavity how mean what
Suresh
seems to me every one is here a doctor and worse part is that even they donot know what to ask.
Muhammad
they know what to ask the problem is how to ask it.too much broken english.
George
dear George ongeche I think if they ask these kind questions and telling themselves as HCPs or medical student's .these are the basic ones go ask something more interesting .
Muhammad
what is blood red
Ahmad Reply
what is human anatomy?
Arpita Reply
tell me what is human anatomy?
Arpita
what is Openstax?
Arpita
arpita jana I think it's not the forum to ask such basic question...
Muhammad
study of structure of an object in this case human body.
Suresh
what are deferent between trasemicacid and vitamin k
Ubah Reply
This medication is used to treat heavy bleeding during your menstrual period. Tranexamic acid works by slowing the breakdown of blood clots, which helps to prevent prolonged bleeding. It belongs to a class of drugs known as antifibrinolytics
Muhammad
jj
John
In the body, vitamin K plays a major role in blood clotting. So it is used to reverse the effects of “blood thinning” medications when too much is given; to prevent clotting problems in newborns who don’t have enough vitamin K; and to treat bleeding caused by medications including salicylates, sulfo
Muhammad
Vitamin K plays a key role in helping the blood clot, preventing excessive bleeding. Unlike many other vitamins, vitamin K is not typically used as a dietary supplement. Vitamin K is actually a group of compounds. The most important of these compounds appears to be vitamin K1 and vitamin K2. Vitami
Muhammad
how much tha total vertebrea bone
Muhammad
26 vertebrea bone
Bhumi
wathe is blood function
dhena Reply
Blood, fluid that transports oxygen and nutrients to the cells and carries away carbon dioxide and other waste products. ... It is a tissue because it is a collection of similar specialized cells that serve particular functions. These cells are suspended in a liquid matrix (plasma), which makes the 
Ashiish
how tissue carries waste matrial
Nadeem
how many bone in human body?
Islam Reply
what is endocrin? plese help many people.
Islam
206
Nadeem
heart layers
Suresh
endoceime is the inner layer of heart
pandit
What is buffer?
Peer Reply
a buffer is a solution that resists a chemical change.
George
Yup it also balances the solutions
Peer
most common side effect reported by users emergency contraceptive pill
Shivvir Reply
spotting .breakbrough bleeding .weightgain.breast tenderness.mood alteration. headache
Ubah
How many systems are in the body?
Irvin Reply
11
AJ
names the systems pls
Joyce
name the systems pls
Joyce
integumentary system, lymphatic system, skeletal system, digestive system, cardiovascular system, reproductive system, respiratory system, urinary system, endocrine system
Irvin
approximately 11 system
Nadeem
what's the meaning of Acidphosphacidic
Tiwa Reply
most common source of phosphoric acid is an 85% aqueous solution; such solutions are colourless, odourless, and non-volatile. The 85% solution is a syrupy liquid, but still pourable. Although phosphoric aciddoes not meet the strict definition of a strongacid, the 85% solution is acidic 
Rose
What is osteoblast and what is osteoclast?
Irvin
osteoblast is the bone forming cells osteoclast is the bone dissolving cells
Juliet
Which of the following is most likely to be found evenly distributed in water in a homogeneous solution? a. sodium ions and chloride ions b. NaCl molecules c. salt crystals d. red blood cells
Ashley Reply
NaCl
Muhammad
b
Shivvir

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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