Maximiliano

Digestive System:
What are the functions if the digestive system?
The digestive system converts food into small molecules that can be used by the cells of the body. Food is processed by the digestive system in four phases:
* Ingestion: Getting food into the system; is the process of putting food into the mouth (the opening of the digestive tract).
* Digestion: As the food passes throughthe digestive system, it is broken in two ways:
1. Mechanical digestion: the physical breakdown of large pieces of food into smaller pieces. Which can be swallowed and accessed by digestive enzymes
2. Chemical digestion: enzymes break down food into the small molecules the body can use.
* Absorption: Once the food has been broken into small molecules, it can be absorbed by cells inthe small intestine. From which there can be transported through the body.
* Elimination: The digestive system cannot digest and absorb all the substances in food that enter the body. Some materials are eliminated from the body as feces.
What occurs during digestion?
During digestion, food travels through the mouth, pharynx, esophagus, stomach, small intestine and large intestine. Mechanicaland Chemical digestion are the two processes by which food is reduced to molecules that can be absorbed.

Digestive system tract:
1. Mouth: The teeth tear and grind food into small pieces. Enzymes in saliva kill some pathogens and start to break down carbohydrates.
Pharynx (Throat): Cavity at the back of the mouth.
Bolus: Once the food is chewed it is called Bolus.
2. Esophagus: Thebolus travels from the mouth to the stomach via the esophagus. Food is squeezed through by peristalsis
Peristalsis: Smooth muscle that contracts allowing bolus trough the esophagus to the stomach.
3. Stomach: Muscle contractions produce churning motion that breaks up food and forms a liquid mixture called chyme. Protein digestion begins.
Chyme: Food that already have been digested by enzymes.4. Small Intestine: Chyme is slowly released into the small intestine. Bile, which is made by the liver, is released from the gallbladder into the small intestine and aids in fat digestion. Enzymes from the pancreas and duodenum complete digestion. Nutrients are absorbed through the small intestine walls.
Bile: Fluid loaded with lipids and salts.
Duodenum: First part of the small intestine.Pancreas: Produces enzymes that break down carbohydrates, proteins, lipids, and nuclei acids.
5. Large Intestine: The large intestine absorbs water as undigested material moves through and it is eliminated as feces from the body through the rectum.

Absorption on the Small intestine:
The small intestine walls are covered by fingerlike projections called villi. Villi are covered with tinyprojections known as microvilli that moves chyme along the surface and absorbed nutrients (carbohydrates and proteins) with the capillaries in the villi. Fats and fatty acids are absorbed by lymph vessels.

Excretory System:
The Excretory system indicates system checks and balances control everything from your blood pressure to the body temperature. Nutrients absorbed, stored, and carefullyreleased when they are needed.
The process in which these metabolic wastes are eliminated to maintain homeostasis is called excretion:
1. Skin: The skin excretes excess water, salts, and a small amount of urea in sweat.
2. Lungs: When exhale, excrete the carbon dioxide and small amounts of water vapor.
3. Liver: Conversion of potentially dangerous nitrogen wastes into less toxic urea(Transported to Kidneys).
4. Kidneys: Removes excess of water, urea, and metabolic wastes from the blood. Ureters transport urine from the kidneys to the urinary bladder, where the urine is stored until it is released through the urethra.

Kidneys Excretion:
How do the kidneys clean the blood?
As waste-laden blood enters the kidneys through the renal artery, the kidney removes urea, excess of...