Functions of the Digestive System

PART A:

1. Identify the parts of the Digestive System on the diagram overleaf(see Diagram 1)

2. Explain the function of each part of the Digestive System identified in the diagram above ?

Introduction: The branch of medicine focused on the digestive system is Gastroenterology. The digestive system is a set of organs that work on food and drink to break them down into substances the body can absorb so that our body can grow, repair itself, have energy to live life.

The Digestive system also gets rid of the waste that the body cannot use. Some organs have a direct input into the breakdown of food where others have an indirect input in the breakdown. The digestive system is made up of 2 parts the alimentary canal is made up of the oral cavity, pharynx, esophagus, stomach, small intestines, and large intestines. In addition to the alimentary canal, there are several important Accessory organs that help your body to digest food they are teeth, tongue, salivary glands, liver, gallbladder, and pancreas.

1. Mouth is where food and drink enter the body and it has many parts that aid in breaking up the food. The teeth which there is 32 of them made up of incisors canine and molars which cut and tear the food breaking it into smaller pieces (mechanical digestion) the tongue moisten the food with mucus and the saliva glands secrete saliva to help break it up into a pulp and amylase work on starch to break it down.so as the food leaves the mouth to go down the throat(pharynx) it is formed into a bolus or pulp which makes swallowing easier. At the top of the larynx there is a flap called the epiglottis which prevents food going towards the lungs but instead letting into the esophagus.

2. Esophagus or windpipe is a muscular tube connecting the throat to the stomach this foodpipe forces the food down to the stomach using muscular waves called peristalsis and along with mucus from the esophagus. At the end of the esophagus there is the cardiac sphincter that allows the bolus into the stomach but prevents the food going back up the esophagus.

3. Stomach: It is C shaped bag that hold food until it is ready to go into the small intestine. The stomach release hydrochloric acid which aid digestion but kills bacteria. The stomach mixes and churns the food with the help of the wave like muscles(peristalsis) and enzymes help to chemically break down the food when food leaves the stomach through the pyloric sphincter it is creamy and is called chime.

4. Small Intestine: It is 7 metre long and it is like a coiled hose and is made up of 3 parts the duodenum, jejunum ileum 90% of the digestion both chemical and mechanical takes place here and some absorption into the bloodstream .The liver produces bile and sends it to the gall bladder and then empties the bile into the duodenum and pancreatic juices are also go into the duodenum in order to help in the breakdown of food. There is villa in the walls of the small intestine which makes absorption into the bloodstream possible.

5. Large Intestine: is a long, thick tube about 2 ½ inches in diameter and about 5 feet long. It wraps around the small intestine. It has 3 parts – ascending colon, the transverse colon, the descending colon. The large intestine receives undigested food from the small intestine and reabsorbs water back into the bloodstream from the faeces. Some undigested carbohydrates cannot be absorbed and form part of the waste that needs to leave the body. There are bacteria in the large intestine which make important substance called vitamin K. Faeces in the large intestine exit the body through the anal canal.

6. The liver is the largest gland in the body it is soft and reddish and brown in colour. It is not considered as a direct part of the digestive system. It produces bile that aids in digestion by breaking down material and help creating waste products that will later need to be eliminated from the body. It destroys harmful bacteria that come from the digestive tract and it stores important vitamins that is in the food

7. The gall bladder is a pear shaped sac attached by the cystic and bile ducts to the liver, stores bile which is made by the liver in a concentrated form until it is needed. the lining has many folds.it secretes the bile when it is needed.it is a thick liquid.

8. The Pancreas is a greyish pink gland organ shaped like a fish it is connected to the duodenum at its tail. The pancreas secretes digestive enzymes into the small intestine to complete the chemical digestion. The cells of the pancreas are divided into the islets of Langerhans(which produce insulin & glucagon) help regulate the sugars in the blood pancreatic juice help to breakdown food. The juices contain lipose, amylase, trysin.

9. Appendix: Is between the small and large intestine it a thin tube 4inches long, it is not known what its function is but it is suggested that it stores good bacteria.

10. Rectum: Is 12cm long it is always empty except when it receives the contents of the colon(faeces) which it stores until it is excreted from the body through the anus.

11. Anus:This is where the faeces leave the body it contains 2 muscles one involuntarily and the other voluntarily which means faeces can be held inside until the person is ready to excrete.

The functions of the digestive system. are now complete they are ingestion, digestion, propulsion, absorption and elimination.(Course Notes (2015) (Tucker, 2012)

3. Outline the composition of Proteins, Fats and Carbohydrates, and explain how each of them are digested and absorbed by the body?

Introduction; All the food we eat needs to be broken down by the body in order for the body to be able to use it. Our diet has to be balanced in order that our body received the correct nutrients necessary for it to be maintained and for our bodies to function properly. The food pyramid outlines the components necessary for balanced healthy diet. See diagram below that helps us to understand the foods that contain Proteins Carbohydrates and fats and how they are beneficial to the body. (Course Notes (2015) (Tucker, 2012)

PART B:

1. Draw a diagram of a typical cell, and state the function of each of it’s Organelles.(See Diagram 2)

Introduction: The cell is the smallest living unit there are 50 trillion cells in the human body that cannot be seen by the naked eye. Cells vary in shape and size and each part in a cell has a job to do which contribute to the function of the cell. A group of similar cells working together form tissue and a number of tissues make up an organ and a number of organs make up an organ system like the digestive system and when these systems work together the result is an individual with all system working together. Below is outlined the main components of an animal cell.

1. Cell Membrane: Regulates and controls transport in(food & Oxygen) and out(CO2 Waste) of the cell and also provides a boundary around the cell.
2. Cytoplasm is a gel like material that lies between the cell membrane and the nucleus, contains water and nutrients and protects the cell.
3. Rough Endoplasmic Reticulum: It has bumpy tissue and produces and moves proteins and hormones around the cell.
4. Smooth Endoplasmic Reticulum: making and distributing molecules depending on the type of cell with a smooth surface.
5. Ribsomes: They are a circle shape and they build protein from amino acids for the cell.
6. Golgi Body: It gathers simple molecules makes them into more complex molecules then packages them into vesicles and then either holds onto the material or sends it out of the cell.
7. Mitochondria: The Powerhouse of the cell as they provide the energy for the cell. The DNA is also found here.it breaks down food and it releases energy to the cell. ATP (Adenosine triphosphate) is produced here and it powers the cells processes.
8. Neuclear Membrane: holds substances inside the Nucleus allows material in and out between nucleus and cytoplasm.it is a protection layer for the nucleus.
9. Neuleous:The main parts are DNA,RNA and proteins, the main function is helping in making ribosomes.
10. Nucleus is a fibrous material, it is the control centre of the cell. It contains chromosomes with the DNA and materials leave the nucleus through the pores.
11. Lysosomes: The disposal system of the cell, they breakdown complex proteins into simplier structures.it digests waste material and helps repair damage to the cell.
12. Cilla: Is a hair like structure on the cell membrane moves substances along the surface of the cell and also helps to move the cell.(Course Notes (2015).

2. Classify tissues into the four main groups; epithelial, connective, muscle, and nervous, give an example of each ? (Table format will suffice)

Introduction: The study of tissue is called histology. Tissues are the collection of cells with a similar structure and function. When the tissues work together they form into an organ. There are 4 types mentioned in table below. (Tucker, 2012)

3. Explain the difference between benign and malignant tumours ?

Benign Tumours: are not cancerous but are a mass of tissue that grow in an uncontrolled way but they can be removed. They do not spread to any other parts of the body and can be quite painful.

Malignant Tumours: they are cancerous and they include cells that grow out of control and they often invade other cells and spread to other parts of the body. When a malignant tumour is removed there is a possibility that cancer will reappear in another part of the body for example a malignant tumour in the pancreas may reappear in the liver.(Course Notes (2015).

PART C:

1. Label the urinary system using the diagram overleaf. (See diagram 3)

2. Explain the structure and function of each element of the Urinary System ? (5 marks)

Introduction to Urinary System: Theurinary systemhelps get rid of waste product called urea from the body, which is produced when certain foods are broken down. The whole system includes two kidneys, two ureters, the bladder, two sphincter muscles and the urethra. Urine produced by the kidneys travels down the ureters to the bladder, and leaves the body through the urethra.

The kidney is bean shaped and 11cm long. 25% of the blood that is in circulation goes through the kidneys there are 2 of them and they are reddish brown in colour it is made up of cortex on the outside and the medulla on the inside. Each kidney has on its surface more than a million twisted tubes called nephrons. The function of the kidneys is to filter out waste and toxins, reabsorb nutrients such as glucose and protein and then excrete waste. It is also responsible for osmoregulation which balances water and salts in the blood.,

Ureter carries urine from the kidney to the bladder and when there is fluid in them it makes the urine flow towards the bladder like the kidney there are 2 of them one attached to each kidney. The walls are thick and are able to contract they are situated between the kidneys and the bladder.

Bladder it is a muscular sac like organ situated between ureter and urethra.it can expand when urine goes into it and then contract when urine leaves it. Its function is to store urine and send a message to the brain when it needs to be emptied.

Urethra is a narrow tube longer in men that women its function is to take urine from the body to the outside but also takes semen to outside in men.(Course Notes (2015).

3. Draw the structure of a Nephron and explain how it produces urine Diagram 4 ? (Google Images)

There are over 2 million nephrons in the kidneys of an adult. (Tucker, 2012) There are a several structures that make up the nephron. The Glomerulus are tiny capillaries that look like a ball of wool and act as sieve where the blood is filtered. The glomerulus is surrounded by the Bowman’s Capsule.

The Bowman’s capsule absorbs the material that is filtered from the glomerulus. As a result of the filtration process useful substances flow into the Tubule and from there they are reabsorbed into the bloodstream.The remaining substances in the tubule and any water that is useful is absorbed into the bloodstream. The material that is leftover is 95% water and cannot be used by the body it is called urine and this needs to be eliminated from the body. The urine moves from the tubule to the ureter. see diagram attached on separate sheet

4. Name and explain three diseases / disorders which affect the urinary system ?

Kidney Stones: The medical name for stones in the kidneys is Nephrolithiasis. It occurs when a solid mass of material forms together within the renal pelvis, bladder or ureters, After the Kidney stone has formed it will try to pass out in the urine but because of its size it will not be able to do so and this can cause severe pain in the abdomen or groin. There are several procedures to remove or break them down. Depending on the size will determine the treatment required if they are small your GP can give you medication that will reduce the kidney stone in size and then allow them to be passed out in the urine if they are much larger surgery may be required. This condition happens more frequently in men than in women.

Urethritis:Is the swelling of the urethra resulting in a very painful discharge of urine sometimes caused by infection. There is 2 types of urethritis Gonococcal and nonspecific urethritis and this is caused by a big number of bacteria, yeast or chlamydia, it is diagnosed by sending a sample of a discharge from the urethra to the lab. Treatment will depend on the cause and appropriate antibiotics would clear the problem.

Pyelonephritis is a bacterial or viral infection of the kidney and it can spread if not treated. People most at risk for pyelonephritis are those who have a bladder infection or a problem in the urinary tract. the possible symptoms are painful urination, groin pain, nausea and fever. In most cases the bacterial infection can be treated by antibiotics, it can be diagnosed in a variety of different ways through analysis of a urine sample and looking for the presence of white blood cells and bacteria, and through Ultrasound. http://www.niddk.nih.gov/health-information/health-topics/kidney-disease/pyelonephritis-kidney-infection/Pages/index.aspx#1

Bibliography/References

Tucker, L., 2012. An Introductory Guide to Anatomy & Physiology. 4th ed. London: EMS Publishing.

John FentonPage 1