Some of the chemical potential energy from the conversion of glucose to pyruvic acid is transferred to NADH and ATP.
It is required for all cellular functions.
It provides energy for muscle contraction and for the transmission of electrical signals in the nervous system, and is used to build organic molecule that are required for cells and tissues.
When the amount of ATP is greater than the body's requirements, the liver uses the excess to make food.
There is a form of sugar in the body.
When blood sugar goes down, the body's immune system fights off infections.
Skeletal muscle is used for intense exercise.
The storage of excess energy is an evolutionarily important step in helping animals deal with mobility, food shortages, and famine.
Obesity is a major health concern in the United States, and there is a growing focus on reducing it and the diseases it may lead to, such as type-2 diabetes, cancers of the colon and breast, and cardiovascular disease.
Calorific foods have more calories per unit mass than non-calorific ones.
One gram of fat has nine calories, one gram ofCarbohydrate has four calories, and one gram ofProtein has four calories.
Animals like to eat food with higher energy content.
The signals of hunger and satiety are sent to the brain's hypothalamus region.
Foods that are rich in fat are more likely to promote satiety.
The liver is able to synthesise glycogen by using excessCarbohydrate andATP.
The pyruvate is used to synthesise fat acids.
Excess pyruvate is converted into molecule that leads to the synthesis of fat in the body.
The fat cells in the body are used to store fat for later use.
Some animals benefit from being overweight.
Body fat helps polar bears and seals keep their body heat.
Body fat provides energy when food is hard to come by.
Fats allow mammals to access energy when there is not enough food to go around.
Obtaining nutrition and energy from food is a multistep process.
The act of taking in food is the first step for true animals.
Digestion, absorption, and elimination follow.
The steps will be discussed in detail in the following sections.
The large molecule found in intact food can't pass through the cells.
Animals need to be able to use the organic and nutrients in the food.
Ingestion is the process of eating.
The teeth, saliva, and tongue play an important role in mastication.
While the food is being broken down, saliva begins to process it.
The combined action of these processes makes the food into a soft mass that can be swallowed and travel the length of the esophagus.
It is important to break macromolecules into smaller fragments that can be absorbed.
Simple sugar can be used as a substitute for large, complex molecule of proteins, polysaccharides, and lipids.
Different organs are involved in the digestion process.
The digested components are discussed in the following sections.
The breakdown of food into maltose begins with the salivaryidase amylase.
There is no significant digestion of the food as it travels through the stomach.
mucous for lubrication is produced by the esophagus.
The amylase is stopped in the stomach by the acidic environment.
The duodenum is where the next step of digestion takes place.
The chyme from the stomach enters the duodenum and mixes with the other body fluids.
Pancreatic juices contain amylase, a disaccharide, which breaks down starch and glycogen into maltose.
maltose is broken into sugar.
Other disaccharides are broken down by lactase and sucrase.
Sucrase and lactase break down "table sugar" into sugars.
The monosaccharides are absorbed and can be used to harness energy.
The monosaccharides are taken to the different parts of the body.
Digestion of sugars is done by a number of enzymes.
amylase and maltase break down the sugars into sugars.
Lactose and sucrose are broken down by lactase.
The stomach is where a large part of digestion takes place.
The pepsin plays an important role in the breakdown of the intact and short chains of the peptides.
Reduce the peptides to smaller ones.
Trypsin elastase, chymotrypsin, and othertrypsins are produced by the pancreas and released into the duodenum where they act on the chyme.
Further breakdown of peptides to single amino acids is aided by peptidases.
Through the small intestines, the amino acids are absorbed into the bloodstream.
The stomach is where the process of digestion begins.
The stomach contains lingual lipase and gastric lipase.
The majority of lipid digestion takes place in the small intestine.
The release of bile is triggered when chyme enters the duodenum.
Emulsification is a process in which the large sphinxes are broken down into smaller sphinxes.
The chyme has more of these small clumps than large ones.
In the presence of water, lysins aggregate to form droplets to minimize exposure to water.
bile salts are an amphipathic, meaning they contain both hydrophilic and hydrophobic parts.
The bile salts can interface with both water and lipids on one side.
By doing that, bile salts help to clot the large fat droplets into the small fat droplets.
Lipases are found in Pancreatic juices.
The surface area of the lipids in the chyme can't be used for lipases if the chyme is large.
By forming an emulsion, bile salts increase the surface area of the lipids.
The lipases can act on the lipids more efficiently and digest them, as detailed in Lipases.
These molecules can enter the cells through the cell's cell wall.
Small spheres called micelles are formed by the bile salts and long-chain fatty acids.
The micelles move into the brush border of the small intestine absorptive cells where the long-chain fatty acids and monoglycerides diffuse out of the micelles into the absorptive cells leaving the micelles behind in the chyme.
The long-chain fatty acids and monoglycerides recombine in the absorptive cells to form triglycerides.
Cholesterol, triglycerides, and other lipids are on the surface of chylomicrons.
The surface is made up of the heads of phospholipids.
They allow the chylomicron to move in an environment that doesn't expose the lipids to water.
The cells are left via exocytosis.
The blood enters the subclavian vein.
Cholesterol is absorbed in the small intestine.
Vitamins are either water-soluble or lipid-soluble.
The vitamins are absorbed in the same way.
It is important to consume some amount of fat to help absorption of vitamins.
Water-soluble vitamins can be absorbed into the bloodstream.
There is a link to learn about the digestion of fat, cholesterol, and sugar.
The process of food digestion begins in the mouth and ends in the rectum.
The elimination of undigested food and waste products is the final step in digestion.
Most of the water is absorbed in the colon, where the undigested food material enters.
The colon is home to a microflora called "intestinal flora" that aids in the digestion process.
The semi-solid waste is stored in the rectum after being moved through the colon.
The rectum expands as it stores fecal matter, triggering the neural signals required to set up the urge to eliminate.
The rectum is used to eliminate the solid waste.
There are a lot of health concerns that affect digestion.
Excess water removal in the colon causes feces to be hardened.
If there is not enough water removed from the feces, it can lead to scurvy.
There are manybacteria that affect the water reabsorption in the colon and result in excessive diarrhea.