Digestion to metabolism a quick break down of what our bodies do with food

It's a tricky topic, with this blog post I’m going break down the processes it takes to absorb food, the types of digestion, and metabolism.

First of all food must be eaten to start the processes of digestion, absorption, and metabolize. Food must be changed into simpler substances for absorption and even after that the food is made even simpler so that cells can get the nutrients needed to sustain life. Preparing food for the body uses many processes and steps, but the main steps are: Digestion, Absorption, Transport, and last metabolism.

Digestion- Is the process of food being broken down in the gastrointestinal tract (GI tract) to release nutrients in forms for the body to absorb.

Absorption- Is the process of nutrients that are taken into cells that line the GI tract.

Transport- Is the movement of nutrients through the circulatory system from one area of the body to another.  

Metabolism-The vast number of chemical changes in the cell ultimately produced the materials that are essential for energy, tissue building, and metabolic controls.

There are two types of digestion, mechanical and chemical. Together these two actions change food so that the overall process of digestion and absorption continues in the body.

Mechanical uses muscles and nerves. Starting in the mouth, muscles and nerves in the walls of GI tract coordinate actions to provide digestion. Food being broken down starts the automatic response to break up food mass and move it down the digestive pathway.

Muscles generally use two types of movements 1) muscle ton or tonic contractions which makes sure the continuous movement of food mass and valve control along the way. 2) Periodic muscles contraction and relaxation. The rhythmic waves that mix the food mass and move it forward.

Nerves regulate muscular action in the GI tract. These are complex networks of nerves called the intramural nerve plexus that extend from the esophagus to the anus. These nerves do three things 1) control muscle tone in the wall. 2) Regulate the rate and intensity of the alternate muscle contractions. 3) Coordinate all various movements in the digestion process.

Chemical digestion uses a series of secretions that work together in digestion of food. There are five different types of chemicals or substances involved. 1) Hydrochloric acid and buffer ions- are used to correct pH for enzymes. 2) Enzymes- are proteins of specific kind/quantity for breaking down nutrients. 3) Mucus- lubricates and protects the mucosal tissue that lines the GI tract. 4) Water and electrolytes- products of digestion are carried and circulated through the GI tract and also into tissues. 5) Bile- made in the liver and stored in gallbladder, bile is used to divide fat into smaller pieces to expose more surface area in the body.

 

Secretory cells are found in the intestinal tract and close to the pancreas and liver to help trigger chemical digestion. These cells or glands are stimulated by three things 1) presence of food 2) nerve impulses 3) hormonal stimuli.

Absorption and Transport- After food has been broken down and changed into simple end products the cells of the body are ready to absorb the nutrients from the food. Carbohydrates, fats, and protein have been broken down and the body is now ready to absorb and transport the nutrients provided. For vitamins and minerals, this is the gatekeeper that determines how much of the nutrient provided will be kept for the bodies use. *There is some result that some nutrients won’t be absorbed because *of nutrients bioavailability which is 1) amount of nutrient present to the GI tract a 2) the competition of nutrients for common absorptive sites and 3) *the form the nutrient is present.*

Absorption process happens in the small and large intestine. *There are two 4 types of absorption* 1) simple diffusion- force by which particles move outward in all directions from an greater concentration to lesser concentration 2) facilitated diffusion- same as simple but uses protein channel for the carrier-assisted movement of larger substances across the mucosal cell membrane 3) Active transport- force by which particles move against their concentrations gradient. *Usually need a carrier* partner to help ferry the particles across the membrane 4) pinocytosis- penetration of larger materials by attaching to thicker cell membrane and being engulfed by the cell.

Transport process happens in the vascular system and lymphatic system. This is the transport of nutrients to various cells in the body. Vascular system- is composed of veins and arteries and its responsibilities are supplying the entire body with nutrients, oxygen, and vital substances that are necessary for *life like blood.*Lymphatic system- are lymph vessels and villi (the lacteals) are for fatty materials and are not water soluble so this is the route that is provided through vessels of the body that will enter to the bloodstream through the thoracic duct.

Metabolism is the outcome of all the nutrients that was digested, absorbed, and transported. Now the nutrients can be converted into needed energy or stored in the body for later use. The energy used is our fuel. The mitochondrion of the cells is the work the center of the metabolic reactions. The two types of metabolism are catabolism and anabolism. Catabolism is used for breaking down large substances into smaller units (ex: stored glycogen into glucose). Anabolism is the opposite and is the process of building large substances from smaller particles (ex: complex protein to single amino acids).

I will go deeper into the processes involved in metabolism in a later blog because it gets to be technical. This is just a generalization of what the body does with our food.