Digestive System, Respiratory and Excretory System

Digestive System:

Digestion or the breaking down of food into small molecules that will be absorbed into our bloodstream begins when you put food in your mouth and begin to chew. Your teeth help to break the food apart, saliva helps to soften the food and your tongue helps to push the food into your throat when you are ready to swallow.

When we swallow the food goes into a tube called the esophagus. The esophagus is a muscular tube that is connected to the stomach. The muscles that surround the esophagus help to squeeze and push the food into the stomach. The process by which food moves down the esophagus is called peristalsis.

We can swallow upside down because the muscles around the esophagus are strong enough to push the food up to your stomach.

The stomach is a sack that receives the food from the esophagus. Your stomach is located just below the heart. The stomach makes digestive juices (acids and enzymes) that help to break our food down into a thick liquid or paste. This thick liquid or paste is called chyme. Your stomach is a muscular organ that is able to move in order to mix the food with digestive juices. Food usually remains in the stomach for about two hours.

Stomach:

After leaving the stomach the food enters the small intestine. Your small intestine is a 20-25 feet tube that is coiled up in your abdomen. The center of your small intestine is right behind your belly button. The most important part of digestion takes place in the small intestine. As the thick liquid food paste travels through your small intestine the nutrients (vitamins, minerals, proteins, carbohydrates and fats) are absorbed by millions of tiny finger-like objects called villi and sent into your bloodstream where the nutrients can travel to all your body cells.

Our body does not digest all of the food that we eat. The undigested food leaves the small intestine and then enters the large intestine. The large intestine is about five feet long so it is shorter than the small intestine. The large intestine is however, thicker or wider than the small intestine and that is why it is called the large intestine.

The undigested food enters the large intestine as a liquid paste. In the large intestine, water is removed from the liquid paste turning what is left into solid waste. Remember, liquid paste to solid waste. The solid waste then collects in the rectum at the end of the large intestine and will finally leave the body through an opening called the anus.

Stomach growling occurs when the stomach receives signals from your brain to begin digestion but the stomach is empty. Your brain might sense you're running low on energy (glucose) or even seeing or smelling something you want to eat can get things going. The motion of the stomach muscles begins, but the organ is hollow. The movement of the muscles mixing the acids of the stomach in the hollow space of the stomach produces vibrations we hear as growling, or rumbling, or gurgling.

The obvious solution is to eat, but this is not always practical. Because your body responds to things that you do daily I suspect that people who eat on very regular schedules may be more susceptible to this problem. For example, if the stomach receives food at noon every day then the body will expect food at noon, whether food is present or not.

Respiratory system:

A human respiratory system is a group of the organ that is responsible for taking in oxygen and expelling carbon dioxide. A large amount of energy is produced from the reaction between food and oxygen. This energy is used to perform various life activities. The respiratory system of the human consists of various parts. They are nose, pharynx, larynx, trachea or windpipe and lungs. The main respiratory organ is lungs.The respiratory system also helps the body maintain homeostasis or balance among the many elements of the body’s internal environment.The respiratory system helps the body maintain homeostasis or balance body’s internal environment. The short information about the parts of respiratory system is given below,

1. Nose: It is the primary outermost organ of respiratory system through which air enters and comes out. It consists of cilia and mucus that prevents bacteria and dust particles from entering inside the body. When air passes through the nose, the air is moistened and humidified. The nose is divided into two nasal cavities by the nasal septum.
2. Pharynx: It is the tubular structure that extends from the mouth to larynx. It allows passage for both food and air. At the end of the pharynx, there is flap-like cartilage structure called epiglottis, that prevents food from entering the lungs. Pharynx consists of three parts, upper part nasopharynx, middle part oropharynx and lower part laryngopharynx which is located below the epiglottis.
3. Larynx: It is also known as the voice box. When air enters through the pharynx, it passes through the larynx. It is made of hyoid bone and cartilage that helps regulate the flow of air. It connects laryngopharynx with the trachea. Larynx consists of two foods which are knowns as vocal chords.The pitch and volume of sounds can be controlled by modifying the tension and speed of the vocal folds.
4. Trachea or windpipe: It allows the passage of air into the lungs. The trachea is made of c-shaped ringed cartilage that divides into the right and left bronchus. The right main bronchus is shorter and wider than the left main bronchus. The bronchus when enter or joins with the lungs, it divides into the smaller tube called bronchioles. These bronchioles further divide into tiny grape-like sacs which are known as alveoli. They are very thin where diffusion takes place. They are supplied with blood capillaries. The exchange of oxygen and carbon dioxide takes place in the alveoli.The average adult has about 600 million alveoli in lungs.
5. Lungs: This is the most important part of respiratory system. They are located inside the thorax on the left and right sides. They are surrounded by a membrane that provides them with enough space to expand when they fill up with air. The left lung is smaller in size then right lung. The left lung has only two lobes and right lung has three lobes. The lungs consist of millions of small air sacs called alveoli where gaseous exchange takes place.

Process of respiration are as follows:

When we take in air, the lungs expand and the size of the chest increases. The chest muscles and the diaphragm when return to its original position, the size of the chest decreases. During this condition, the air comes out of the lungs. The healthy man breathes 18 - 20 times in a minute.

The rate of breathing increases during hard work, running, excitement, fear etc.
The atmospheric oxygen passes through nose, pharynx, larynx, trachea and last to lungs where gaseous exchange takes place. The oxygen when reaches the lungs it diffuses into the blood vessels. The carbon dioxide in blood vessels comes out into the lungs. The oxygenated blood reaches into the heart.

With the help of different nerve, the heart pumps out blood into the different parts of the body. The oxygen then reacts with the food and a large amount of energy is produced which is utilized to perform life activities by the various cells, tissues and organs. During the reaction between oxygen and food, energy along with water and carbon dioxide is also produced. The carbon dioxide thus formed reaches the heart and to the lungs through different nerves and blood vessels.

Importance of Respiratory System are as follows:

• It fulfils the necessity of oxygen in our body.
• It helps to remove carbon dioxide from our body.
• Without oxygen, our body cannot perform life activities.
• The neuron cannot transfer electrochemical message in the absence of the oxygen.

Excretory System:

Our body cannot perform life activities without food. Food provides us energy. No living organisms can live without food. Food not only provides energy but it also creates unnecessary things and materials which are known as a waste product. This waste product needs to get removed from our body. Various parts of our body organ take part to remove this waste product from our body like kidneys, skin, urinary bladders, ureter, liver, etc. The main function of an excretory system is to remove waste from the body.

The skin performs excretion through sweat glands. These glands produce sweat that contains salt, excess oils, water, and other unnecessary substances. Similarly, nose and mouth also help to remove waste product like saliva, cough etc. Large intestine also helps in the removal of unwanted food materials. Similarly, lungs help to remove waste gases like carbon dioxide and water. The liver plays a vital role in keeping our body clean. Harmful poisons and chemicals that are either produced in the body or consumed are broken down and detoxified by the liver.

The main excretory product is urine, it removes nitrogenous compounds from our body. It contains a pair of kidneys, urinary bladder,ureter, urethra etc.Kidneys are bean-shaped organs of a reddish brown color that are found in the sides of the vertebral column. It filters waste from the blood. Each kidney contains millions of nephron which help to filter nitrogenous substances from the blood.

Importance of Excretory System are:

• It helps to remove wastes produced by homeostasis.
• Urea and nitrogen which are harmful to our body are removed in the form of urine.
• Various waste materials are produced from the metabolic activities in our body. These waste products are removed from various organs of our body.
• The kidney plays an important role in the removal of the waste product. It removes the waste product in the form of urine and filters the unwanted substance.