Digestive System of the Human Body

Digestive System of the human body is perhaps the most recognized part of all of the body systems as it entails knowledge about food intake – something we are all aware of. The digestive system consists of a group of organs which work together to convert food into energy and extract nutrients to feed the body as well as to excrete waste material.

The human body needs to digest food and use the energy so that it is able to function efficiently, repair itself and remain healthy.

Digestive System of the Human Body

Digestive System of the Human Body

The major physiology functions taking place within the digestive system are as follows:

Ingestion: This is quite simply the intake of food through the mouth. The amount of food in the mouth is an indication of how much the body can handle at any given time.

1. Secretion: About 7 litres of fluid is secreted by the body each day and include saliva (serves to moisten dry food), mucus (forms a protective barrier and lubricant within the GI tract), enzymes (breaks down protein, carbohydrates and lipids into smaller parts), bile (break down large lipids) and hydrochloric acid (digests food chemically and kills bacteria in the food).

2. Mixing and Movement: 3 main processes are used for this process.

A). Swallowing: The oral cavity including teeth and tongue are used to chew and push food through the pharynx and into the esophagus

B). Peristalsis: A muscular wave of movement helping to move partially digested food down the tract. This movement helps to move the food from the esophagus through the stomach and intestines.

C) Segmentation: This is the gentle squeezing movements of the small intestine to allow for increased absorption of nutrients.

4. Digestion: This is the entire method of breaking down food from the mouth right through the stomach and excretion at the end. In effect two processes are taking place simultaneously and that is the mechanical as well as the chemical breakdown of food. The whole process involves all the body organs are described in the anatomical section below.

5. Absorption: The absorption process takes place in the stomach. Substances which are absorbed directly into the blood stream include water and alcohol. After this the walls of the small intestine absorb much of the nutrients. Finally in the large intestine any remaining water and nutrients mainly vitamins B and K are absorbed before the remaining waste is excreted from the body.

6. Excretion: This is the final part of the digestive system and involves defecation of waste matter. The body needs to remove this waste matter to keep the gut clear from indigestible substances.

The anatomy of the Digestive System consists of the following components:


Another name for the mouth is oral cavity. To aid the intake of food the following parts help: teeth, tongue and the salivary glands. Once the teeth have cut the food into small chunks with the help of the moisture from the saliva, the tongue and together with other muscles help to push the food into the pharynx. The teeth are sharp and grinding and the tongue has taste buds which help to give food the taste and texture we deserve. There are 3 sets of salivary glands which also help with the digestion of carbohydrates. This lubrication is also used by the body throughout the mouth, pharynx and esophagus.


Better known as the throat, it has the responsibility of passing food from the back of the mouth down to the esophagus. The pharynx plays a vital part in the respiratory system and this is finely balanced between allowing air through the air valve and food through the other one. This is where the divider of the two known as the epiglottis acts as a switch between food valve and the air valve known as the larynx plays a vital role. Occasionally when we experience choking that is when the epiglottis has not made the switch effectively.


This serves as a connective tube between the pharynx and the stomach. It is constructed of a muscular tube. The role of the esophagus is to push the food into the stomach and the bottom part known as the cardiac sphincter keeps the esophagus closed thus preventing food from escaping the stomach.


The location of the stomach is on the left side of the abdominal cavity, near the diaphragm. As a muscular sac, the role of the stomach is to act much like a storage tank while the body has time to digest large meals properly. The hydrochloric acid combined with the digestive enzymes break down the food further within the stomach itself to help digestion.


In the form of a hose and taking up most of the physical space in the abdominal cavity, the small intestine forms part of the lower gastrointestinal tract. As a coiled long thin tube, but with the ridges and folds allowing for more area space, the role of this intestine is to maximize the absorption of nutrients in the food during this stage of digestion.


Weighing 3 pounds and triangular in shape, the liver, located to the right of the stomach, has many different functions. As the second largest organ of the body its main function is to produce and secrete bile into the small intestine.

By comparison the smaller pear shaped gallbladder has the role of storing and recycling excess bile from the small intestine in order for reuse in the digestion of forthcoming meals.


The pancreas is connected to the duodenum from the head end and the tail end pointing to the abdominal cavity. In order to complete the chemical digestive process of food, the pancreas secretes digestive enzymes into the small intestine. The length is 6 inches and it is short and lumpy in appearance.


This is a longer and thicker tube than the small intestine and wraps around parts of the smaller intestine. This part of the digestive system contains symbiotic bacteria which helps the break-down of waste to help absorb the remainder of the nutrients. It also absorbs water. What is left is the waste called faeces which exits through the anal canal.

Digestive System Image Source: www.infovisual

Part of the Human Body Series: | Skeletal System of the Human Body | Muscular System of the Human Body |  Nervous System of the Human Body | Lymphatic and Immune System of the Human Body |

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Respiratory System of the Human Body

Respiration in the Human Body

Respiratory system of the human body has an important role to play in that it is responsible for the continuous supply of oxygen to all the body cells as well as removing carbon dioxide from the body. The main channels for this process of inhaling oxygen and exhaling carbon dioxide are the mouth and the nose. The human body contains a network of tubes which reach every cell to help the breathing process.

During the actual breathing process, the respiration muscles (which include the intercostal muscles and the diaphragm) work together as a pump, helping to push air into the lungs and then out of them.

Human Respiratory System

Human Respiratory System

Components of the Respiratory System:

Nose and Naval Cavity – This is the main route that the air takes to get into and out of the lungs. Inside the nose cavity there is a membrane lined with mucus which helps to trap dust and germs. Also the hair within the nose helps to control large particles of dust from entering the lungs. The nasopharynx allows only the air to pass for breathing.

Mouth – Serves almost the same purpose as the nose but is not the primary source for breathing. Although the mouth lacks the extra filtrated protection given by the nose, it is in fact a much faster way of getting air to the lungs and does so in larger quantities. The epiglottis which is a cartilage flap plays an important role in that it covers the entrance to larynx when food is being swallowed.

Pharynx – This is a short tube which running from the back of the nasal cavity to the larynx (voice box). It is better known as the throat and consists of 3 parts:

  1. Nasopharynx: Allows air to pass through.
  2. Oropharynx: Allows food and fluid to also pass.
  3. Laryngopharynx: Also allows food and fluids to pass.

Larynx – A short tube which joins the pharynx with the trachea. This part of the throat is associated with the production of speech.

Trachea – This is the actual wind pipe as it serves to be the main entrance to the lungs. It is surrounded by c-shaped cartilage rings.

Bronchi and Bronchioles – The main role of the bronchi and bronchioles is to carry air from the trachea into the lungs. There is a left and right bronchi branching into the left and right lung. From there they further branch into secondary bronchi and then into smaller tertiary bronchi covering the entire lobe of each lung. The very tiny bronchioles then provide air to the lung’s alveoli which are tiny air sacs much like bunches of grapes. This is where the gas exchange takes place.

Lungs – These are sponge like organs protected by the ribcage and their role is to organise a gas exchange system helping the body to receive and emit fresh and used air supply. Internally they consist of a tree like structure. The left and right lung differs slightly in size as the right lung has 3 lobes and the left lung has only 2 lobes.

Respiration Muscles – The lungs are surrounded by muscles which allow air to be pushed in and out of them. The main muscle is the diaphragm which is a thin skeletal muscle lying underneath the lungs and which when contracted, allows more space and therefore air to be pulled into the lungs. When the diaphragm relaxes, it allows air to be exhaled out of the lungs. The intercostal muscles assist the diaphragm with its movements and are known as internal and external intercostal muscles.

Respiratory Disorders:

On occasion there are times when the respiratory system does not function properly. Some of these problems are as a result of the following:

  • Common Colds and Influenza
  • Upper Airway Infection
  • Acute or Chronic Bronchitis
  • Pneumonia
  • Tuberculosis (TB)
  • Pneumothorax
  • Asthma
  • Occupational Diseases
  • Lung Cancer

Healthy Respiratory System:

Refrain from smoking and keep to a healthy immune boosting diet. The environment has an effect in if you work in a hazardous environment whereby you inhale dangerous toxins often, it can have a long term negative effect on the health of your lungs.

For more information on the Respiratory System: learn.fi.edu |                             Image Source: www2.estrellamountain.edu

Part of the Human Body Series: | Skeletal System of the Human Body | Muscular System of the Human Body |  Nervous System of the Human Body | Lymphatic and Immune System of the Human Body |

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Endocrine System of the Human Body

The Endocrine System of the human body is very much a part of the information processing method used by the human body. It consists of the hormones which control all aspects of our body function from single cells right through to the entire development and growth of the human body as well as controlling the emotional states.

Hormones are the chemical messengers of the human body and are made by the endocrine glands. Hormones are important because they are used by the body to regulate tissues or organs. The endocrine system is well integrated into the nervous system and the two systems therefore work well together.

Hormones work much like keys. If they are the right shape, they will fit into an organ such as the pancreas and begin to do the work it has been assigned, in this case to control blood glucose levels in the entire human body.



The Endocrine System consists of a network of Hormone Producing Glands:

Hypothalamus: Situated in the brain, it is the main link between the nerves and the hormones.

Pituitary Gland: Also known as the master gland as it involves two glands in one. It controls many other glands. The nervous system controls:

1. Posterior Pituitary which produces 2 hormones:

a. Vasopressin – Regulates water in body’s cells and causes blood pressure to rise.

b. Oxytocin – Used during childbirth for the womb to contract and lactation to begin.

2. Anterior Pituitary: Usually referred to as the master gland as it triggers other endocrine glands into action as it receives the necessary chemical messages in the bloodstream.

Thyroid Gland: Controls metabolism and secretes thyroxin. When overactive, this hormone has the ability to cause to irritability and when underactive it causes drowsiness. This gland also has the ability to store the hormone produced.

Thymus Gland: Three types of hormones are produced here relating to the development of white blood cells (T-cells) which function in the immune system.

Pineal Gland: Located in the middle of the brain and the size of a pea. This gland produces a hormone known as melatonin which is important for regulating the sleep-wake cycle. It also plays a role in sexual development. But it is generally in charge of regulating activity levels in the body throughout the day.

Heart: The hormone known as antriopeptin is produced here. This hormone reduces blood volume and pressure and regulation of fluid balance.

Adrenal Gland: Outer layer known as cortex produces steroid hormones which are responsible for regulating sodium, potassium and glucose as well as maintaining fluid balance.

Kidney: Erythropoietin is secreted by the kidneys which stimulates the production of red blood cells within the bone marrow.

Stomach: Produces hormones which aid the digestive system.

Pancreas: Insulin and glucagon hormones are produced by this gland. They aid in the control of blood glucose levels in the body.

Intestines: Also produces hormones to aid in digestion just as the stomach does.

Gonads: Ovary/Testes – These produce oestrogen and progesterone in females and androgens which include testosterone in males.

For more information on The Endocrine System: www.betterhealth.vic.gov.au  | Healthy Endocrine System Image Source: www.herbalremediesadvice.org

Part of the Human Body Series: | Skeletal System of the Human Body | Muscular System of the Human Body |  Nervous System of the Human Body | Lymphatic and Immune System of the Human Body |

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