Rectum

The straight part of the colon is the dilated pouch like structure that is preceded by sigmoid colon and followed by anal canal. Before you defecate, the feces is temporarily stored in this gastrointestinal structure which becomes dilated on the arrival of waste material and induces the urge for its elimination through anal verge. The word "rectum" has been derived from a Latin phrase "Rectum Intestinum" which means "straight intestine". As the rectum facts suggest, this organ is about 12 cm in length, and begins at the third sacral vertebrae and is joined with the preceding section of large bowel at rectosigmoid junction. Based on the structure and function of the distal end of large gut, you can divide rectum parts

The primary rectum function is the temporary storage of stool so that you may have some time to reach the place where it can be defecated. As the waste and indigestible materials get entry into it, the canal becomes dilated, thus stretching the muscles lining the rectal region. Stretch receptors are located in the wall of rectum which sense the dilation of the gut and send signal to the nervous system (brain) where these are processed and a response is generated that induces the need for the elimination of waste materials passing through anal canal and getting out through anal verge. However, if you do not go for defecation for a prolonged duration, the stool gets back into the colon for further absorption of fluids which may also result in hardening of stool and constipation.

Small Intestine

Small Intestine Function

Functionally, you will find small gut very important part of gastrointestinal tract as it not only digests major part of the dietary contents but is also meant for absorbing finally broken down food particles. Meanwhile, you cannot underestimate the importance of large intestine and anus function. It’s the place where almost all of the absorption takes place including nutrients, bile salts, vitamins, and so on. Some of the major small intestine function can be listed as under:

Neutralization

The partly digested food that is coming from stomach through pyloric opening is highly acidic in its medium, but the enzymes present in duodenum and other parts of the canal cannot perform their activity as biological catalysts. So as the first and foremost function of the gut, this medium is neutralized and the enzymes are made to act in the most efficient way.

Digestion

After the medium has been made feasible for the enzymatic actions, the digestion of the remaining contents of chyme is accomplished here. As a part of overall small intestine function, different secretions are poured into canal, like bile and pancreatic juice that facilitate the process of breakdown to a greater extent, until the finally digested food particles are ready to be absorbed.

Absorption

Here it is surprising to know that among all the segments of gut, this is the only portion where almost all of the absorption and assimilation of digested food, vitamins and salts, takes place. For the intake of nutrients into the bloodstream, there are specialized cells (e.g. enterocytes) that facilitate the process of absorption. After entering the bloodstream, the food particles are delivered to all the living cells in the body where, by means of metabolic reactions, energy is extracted to accomplish all the vital activities.

Parts of Small Intestine

To enjoy an ideal health and counter the diseases, you must have sound knowledge of different parts of the body with facts. Small bowel is further divided into three structurally and somewhat functionally distinguishable smaller segments, viz. duodenum, jejunum and ileum. In various segments, the three layers of its wall are similar throughout its length, but there do exist certain structural differences among them.

Duodenum
The foremost and shortest part, it is functionally very important as major portion of the chemical digestion takes place here. Varying in length from 10 to 15 centimeter, it is, on the anterior end, connected with stomach, while the posterior end touches jejunum.

Jejunum
Constituting the second part of your small bowel, located between duodenum and ileum, it has the average length of about 8.4 feet or two and a half meter in adult humans. The pH of the medium inside this part of gut may vary between neutral to slightly alkaline, i.e. 7 to 9. The enterocytes are the specialized cells present in the lining of the canal that are actively involved in the absorption of small particles of food that were digested by enzymes in duodenum.

Ileum
This final section of small gut, on one hand, continues with jejunum, while on the other, it makes a connection with colon through ileocecal valve. In adult humans, it may vary from 7 to 14 feet in length, and the pH of the medium is same as that of jejunum which is neutral to a bit alkaline. Its major function is to absorb any nutrients that were not absorbed in the preceding sections of the gut. However, it is particularly involved in the absorption of bile salts and vitamins

Pancreas

Pancreas is one of the extrinsic glands of the digestive system. It has mixed endocrine and exocrine functions, and is present outside the wall of the digestive tract. In order to fully understand, "What is pancreas?" you must know its location, functions and diseases. The exocrine part secrets pancreatic juice into the duodenum; the juice contains a number of digestive enzymes and pro enzymes that help digest the food. The endocrine part produces hormones such as insulin that play significant role in the absorption, metabolism and storage of nutrients such as glucose. Dysfunction in the endocrine part of the pancreas leads to diabetes mellitus.

 A normal pancreas is about 12 to 15 cm long and weighs about 110 gm. Pancreas location is behind the stomach and it lies more or less transversely in the posterior wall of the abdomen; it has duodenum on its right and spleen on its left. It has a head that lies within the curvature of the duodenum, a neck that connects the head to the body and a body that blunts into its tail to touch the spleen. Cancer of the pancreas usually involves the head and accounts for most of the cases of extrahepatic biliary obstruction.

About 1500 ml of pancreatic juice is secreted everyday which contains many digestive enzymes, water and various ions such as bicarbonate, sodium, potassium.

pH of the pancreatic juice is alkaline in nature which helps neutralize the gastric content entering the duodenum from the stomach.

Pancreatic enzymes and pro-enzymes (zymogens) are essential for the digestion of protein, carbohydrate and fat constituents of food that we eat every day.

Endocrine part of pancreas secrets two important hormones - insulin and glucagon - both of which are secreted reciprocally from pancreas and also act reciprocally in most circumstances. In a nutshell, insulin increases storage of glucose, fatty acids and amino acids. On the other hand glucagon is a catabolic hormone so it mobilizes glucose, fatty acids and amino acids from stores into the bloodstream.

Secretion of the pancreatic juice is primarily regulated by two hormones -

Secretin

Cholecystokinin (CCK)

Both of these hormones are produced by specialized cells of the duodenum. They are secreted in response to gastric acid entering the duodenum from the stomach and in response to products of protein and fat digestion (e.g. small peptides, amino acids and fatty acids). Both hormones act synergistically in response to a meal and cause a large volume of alkaline pancreatic juice rich in digestive enzymes to be released.

Lungs

Lungs are the major organ of our respiratory system. They help you obtain oxygen and get rid of carbon dioxide. The gaseous exchange takes place in the tiny air sacs which have just one-cell thick walls. Blood absorbs oxygen and delivers it to every individual cell in the body.

A cylindrical tube, called trachea, is the main link between the human lungs and the nose and mouth. When we breathe in, air travels through the trachea to the main respiratory organs. As the trachea moves down the chest, it splits into two branches, i.e. bronchi, one for each lung.

Each bronchus then further subdivides into several smaller tubes, namely, bronchioles. Thus, each lung contains many bronchioles. They spread all over its structure in order to ensure an even distribution of oxygen. You can view the details in the lungs diagram.

For oxygen to be able to reach all the parts of our body, it dissolves into the blood. The blood stream then distributes oxygen to the entire body. Therefore, there has to be a supply of blood vessels in the lungs. These blood vessels are present on minute, sac-like structures, the alveoli.

The alveolar sacs are present at the end of bronchioles. There are numerous alveoli in each lung. This is to provide the maximum surface area for the exchange of oxygen as well as carbon dioxide with the blood stream.

Do you know the expanse combined surface area of all the tiny alveolar sacs in the lungs? Quite unbelievably, it is equal to the area of an entire tennis court.

It is possible for a person to survive with just one lung. However, he would be weaker than normal individuals who have a pair of these organs.

On average, the volume of air that the respiratory system takes in every day is approximately 9,000 liters!

The pulmonary structures of newly born babies breathe at a faster rate in comparison with those of adults.

Your pulmonary organs play an important role in respiration system of the body. Oxygen moves in when you inhale air. The air travels from the external air passages (mouth and nose) down the trachea and finally into the alveoli through the bronchus and bronchioles.

This oxygen dissolves into the layer of moisture around each alveoli and finally moves into blood capillaries. In this way, a lung plays a vital role in providing oxygen to all the body organs.

It is important for your body to get rid of carbon dioxide which is a waste product of respiration. Once again, these are the pulmonary organs which help in the elimination of this toxic waste product. The path of carbon dioxide from the blood to the external environment is the reverse of the path that the oxygen takes to enter the blood stream.

Kidneys

Location of kidneys is of particular importance in your body. There are two bean shaped kidneys in the human body. A normal kidney is about 2.5 cm thick, 10 cm long and 5 cm wide. They are reddish-brown in color. Each weighs around 130 gm in adults. Both kidneys receive blood from the renal artery. In a resting adult nearly 1.2 to 1.4 liters of blood flows through both kidneys in one minute. It means every 4 to 5 minutes all the circulating blood in the body passes through the kidneys. Kidneys help remove excess salt, water and waste products from the bloodstream.

Like other endocrine organs, kidneys also secrete important hormones such as rennin and erythropoietin into the circulation. These hormones play a significant role in the production of blood cells. In addition, they also assist in the regulation of blood pressure.

It won’t be wrong to call kidney as the natural filter in your body. Its job is to purify blood and make it free from all the waste substances that it has collected from every individual cell. but how is such an important kidneys function executed? For this purpose, you need to study the kidney anatomy.

Location Of KidneysYou can better understand the anatomy of kidneys from the labelled diagrams. One of these is shown here. In the kidney images, you can see that a nephron serves as the basic structural and functional unit. There are a large number of nephrons in each of these organs. They make a direct connection with a complex network of blood vessels.

From the kidneys pictures, you can easily distinguish among different parts, such as medulla, cortex and the renal pelvis. On the side of the renal hilum, you will come across renal artery and the renal vein. From the renal pelvis, there emerges a ureter which descends downward to reach bladder. It also indicates that the location of kidneys is directly above the bladder.

The function of kidneys is to produce urine by filtering large quantities of fluid from the blood plasma. Urine consists of approximately 95% water. Urine also contains urea, creatinine, phenols, phosphate, potassium and sulfates. There are also nitrates and a large amount of uric acid.

Urea, uric acid and creatinine are all nitrogenous waste products. Nitrogen containing compounds are among the most toxic metabolic waste substances. Your body produces them as a result of various metabolic processes.

You can express the level of nitrogenous waste products in our blood as BUN (blood urea nitrogen). In healthy adults, normal BUN level ranges from 8 mg/dL to 25 mg/dL. A high level of BUN indicates renal insufficiency, i.e. one of the kidney problems.

The volume and composition of urine that the kidneys produce and excrete every day depend crucially on various factors. These factors include fluid intake, diet, renal functions, climate, metabolic activities of cells. Meanwhile, the presence or absence of systemic diseases also has a role to play in this regard.

Gall Bladder

What is gallbladder? The gallbladder facts reveal that it has to play an important role in the breakdown of food items and, consequently, their absorption into the blood. Before learning gallbladder definition, you should know about the extent of digestive system. The digestive system is perhaps the largest system in the human body. It has many accessory organs and glands to perform its overall digestive function
According to gallbladder definition, it is a small gland at the base of liver. Its main job is to assist in the emulsification, digestion and absorption of fats in food. The liver secretes the bile and transfers it to gall bladder for temporary storage.

Another gallbladder function is to concentrate the alkaline fluid that contains salts, pigments, fats and about 85% watery component.

Recent gallbladder information suggests that this structure in an adult human would measure about 8 x 4 cm or a bid more. It secretes bile juice to facilitate digestive processes of oily diet. The organ has divisions into three parts, which are neck, body and fundus. The neck of gall bladder establishes a connection with liver through common bile duct and transcends its secretions through it. Fundus appears at the opposite end of this pear-shaped organ, while body lies in its proximity away from the neck.
Bile Juice Secretion & Storage: The liver secretes the bile juice and pours it into gallbladder. The gallbladder then stores the bile juice for some time.

As the need arises, the bile juice enters into the duodenum of small intestine. This commonly happens after taking food that is rich in cholesterol or other lipids.

Breakdown and Digestion: Do you know the bile from the gall bladder emulsifies fat molecules? As a result, the fat digesting enzymes, like lipase, can carry out their breakdown and digestion effectively.

Bile Concentration: Here is another of the interesting facts about the gallbladder in the digestive system. That is, the biliary vesicle achieves about 10 times concentration of bile.

Formation of Gallstones: Frequent and prolonged intake of fatty foods, would result in excessive concentration and hardening of bile juice. It will, in turn, result in the formation of gallbladder stones.

Gallbladder Removal: Removing gallbladder does not interfere much with fat metabolism and there direct secretion of bile into the intestine.

Inflammatory disorder: Inflammatory disorder of the gallbladder is also common among people who have been suffering from chronic infection of typhoid.

The gallstone are usually small, hardened deposits that measure not more than a few millimeters. That is why, in most of the cases, they do not cause any severe symptoms and go without detection for years. At the later stage, however, they lead to pain, infection and inflammation of the organ.

The gallstones can be of two major types, i.e. pigment stones and cholesterol stones. The pigment stones result from the accumulation of calcium bilirubinate – a chemical produced after the breakdown of red blood cells. In the latter case, accumulation of cholesterol is the sole cause for the formation of such stones.

There are usually very rare cases of this type of cancer. However, there are chances for its spreading to other parts of the body. In that case, the disease becomes fatal. If there is timely discovery of the gallbladder cancer, it is easily treatable. But, unfortunately, it is one of the gallbladder facts that in most of the cases, the cancer is diagnosed at a very later stage. The primary reason behind delay in the diagnosis is that such type of cancer does not cause any obvious signs or symptoms soon after its onset.

Bronchi

Do you have any brief idea about “What is bronchi?”. Well, it is a plural form of bronchus. Here it becomes pertinent to define bronchus. A bronchus, on the other hand, can be defined as either of the two branches of trachea which lead directly to the lungs. So, the appendix definition makes it clear that a bronchus is actually a sub-division of the windpipe. The trachea or windpipe serves as a passage for airflow between mouth or larynx and the lungs.

Structurally composed of cartilaginous material, the air passages show a significant amount of flexibility. This flexibility, in turn, substantially contributes to their functioning efficiency. Any abnormal condition in the structure gives rise to great disturbance and severe symptoms of the respiratory system. But a number of remedial strategies are available for almost all of such disorders.

                          
Though their walls do not let the respiratory gases pass across them, the bronchial canals are the main channels for the passage of airstream towards the major respiratory organs. They also make significant contribution to the protection of lungs against germs and dirt particles. The germs and dirt particles are trapped in the mucous lining of the lumen.

Afterwards, there is upward expelling and removal of such unwanted things out of the windpipe with the help of ciliated cells. The hyaline cartilaginous material that forms the D-shaped incomplete rings of the bronchial walls prevents the tubes from collapsing and obstructing the flow of air.

However, with the passage of time as you grow older, this soft flexible material becomes a hard and rigid bony substance. Consequently, it reduces the overall efficiency of the structure. The alveolar sacs (or alveoli) form as a result of many subdivisions of the mainstem bronchi. And these are the places where the exchange of respiratory gases takes place.

There are a number of respiratory disorders that affect the subdivisions of windpipe at different levels, i.e. bronchi, bronchioles and alveoli or respiratory sacs. For example, bronchitis – as the very name suggests – is the inflammatory disorder of bronchi. It may occur in either of the two major forms, viz. chronic and acute one.

Chronic bronchitis results from the prolonged exposure to the irritants and smoking habits. While acute form is the result of the bacterial and viral infections. As a response to the allergens (antigens producing abnormally vigorous immune response), hyperactivity occurs in the bronchial canals. People call this condition as asthma.

Because of its vertical position, the right main bronchus is more vulnerable to the disorders. It is because the germs and dust particles present in the atmospheric air get entry into the right lung quite easily. Over there, they cause mild or severe medical conditions.