Explain the need for nutrition by living organisms.
BIOLOGY ASSIGNMENT
) EXPLAIN THE NEED FOR NUTRITION BY LIVING ORGANISMS.
Nutrition is the science of how our bodies obtain energy, build tissue, and control body functions using materials supplied in the food we eat. Nutrients are chemical substances needed by the body. The need for nutrition by living organisms is essential for survival in the sense that it provides energy and material for growth and repair and for the general function of the human system and its maintenance. Different foods we eat contain at least one of the seven major nutrients namely; carbohydrate, protein, fats, vitamins, minerals, roughages and water. There are two types of nutrition Heterotrops and Autotrops -
We are unable to make our own food from the sun as plants do. We get our food by eating plants or other animals.
Our bodies need food for a variety of reasons:
Growth: Food, especially proteins, makes new cells and tissues as we grow.
Energy: The body is like a working machine that needs energy to keep it going. During cellular respiration food is changed into energy for many activities e.g. the heart pumping blood around our bodies. Energy rich foods are carbohydrates and fats.
Replacing worn out and damaged tissues: Our cells are constantly dying or getting old so they need to be replaced. Red blood cells carry oxygen needed to live and therefore must be replaced regularly. Proteins, fats and mineral salts are especially important.
2) EXPLAIN WHY THE MAJOR NUTRIENTS ARE REQUIRED BY HUMANS.
There are seven major nutrients, which are required by humans;
Carbohydrates-are compounds made of carbon, hydrogen, and oxygen (C6 H12 O6) They are energy providing foods for the body cells, they provide instant energy. These include rice, potatoes, pasta, bread and all starchy foods and sugars. There are three types of carbohydrates-monosaccharides- are single sugars such as glucose and fructose a sugar found in fruits, disaccharides- consist of two single sugars linked together, these include table sugar lactose, and maltose, and polysaccharides - is a long chain of sugars such as those in bread, pasta, and potatoes.
Proteins-are body building foods, which provide nutrients for making, growing and repairing, damaged cells. Proteins are made up of smaller units called amino acids. These include red meat, fish, eggs, beans, nuts and poultry.
Fats and Oils-are also sources of stored energy and may contain fat soluble vitamins A, D, E and K. They protect vital organs, keep our skin from drying out and insulate the body against changes in environmental temperature. Fatty Acids are classified as either saturated; (fats in animals) or unsaturated. ( from plants )These include oil, butter, fat and dairy products.
Vitamins-are complex organic molecules that are needed by the body in very small amounts that serve as coenzymes. They maintain normal growth and metabolism. These include fresh fruits and vegetables. There are two main types of vitamins a) water soluble vitamins including B and C and b) fat soluble vitamins A, D, E, and K. If the body does not receive sufficient supply of vitamins, it could lead to vitamin deficiency diseases.
Minerals-are inorganic substances required for the normal function of the body. These include calcium in dairy products for bones and teeth, iron for transporting oxygen in blood potassium, sodium, calcium, and magnesium for the function of nerves and muscles.
Roughages-include cereals, bread, fruit and vegetables, this is to prevent constipation, and bowel disorders. It also makes you feel full.
Water-is the most important nutrient, it allows materials to dissolve, helps to regulate body temperature, and acts as the solvent in which food and enzymes are dissolved in the digestion system. Most water is replaced by drinking liquids, but it is also found in most foods we eat and as by-products of cellular respiration.
3) IDENTIFY AND EXPLAIN FULLY THE MAIN STAGES OF DIGESTION AND JUSTIFY THE NEED FOR EACH PROCESS.
DIGESTION is the breakdown of food into simpler molecules that can be absorbed and used by the body. It begins with the mouth through the pharynx, oesophagus, stomach, small intestine, large intestine, rectum and then anus.
The first step of digestion is by ingesting the food; this is mechanically broken down and crushed by the teeth otherwise known as "mastication" the tongue helps to keep the food between the chewing surfaces of the upper and lower teeth by manipulating it against the hard plate." During this process, the salivary glands produce saliva and a digestive enzyme called salivary. The enzymes in the saliva kill bacteria and begin the process of chemical digestion by breaking down starches to sugars. The mucus in the saliva softens and lubricates the food and helps hold the food together. The salivary amylase begins the chemical digestion of carbohydrates by breaking down some starch into disaccharide maltose.
Once the teeth and salivary glands have completed the initial processing, by gathering the food together in a ball called bolus, the tongue pushes it towards the back of the mouth and into the pharynx. As it moves into the pharynx it presses down on a small flap called the epiglottis, this is to prevent the food from entering the respiratory track to avoid the risk of choking. The bolus then enters the oesophagus, which is helped by its muscles to move towards the stomach. When it reaches the stomach, the stomach walls contract in opposite directions while mixing and churning the food. Chemical digestion starts the action of hydrochloric acid and pepsin; these are both secreted by the gastric glands in the stomach. Pepsin breaks down proteins into shorter chains of amino acids called peptides. Another fluid secreted by the stomach is mucus; this lubricates the food making it more easier to travel through the digestive tract.
After about three hours of chemical treatment in the stomach the food is reduced to a soft pulp called chyme and moves into the duodenum and then into the small intestine. The pancreas secretes pancreatic juice into the small intestine. The pancreatic juice contains enzymes that digest carbohydrates, proteins, and fats. The pancreatic juice also contains sodium bicarbonate, which neutralizes the hydrochloric acid in chyme protecting the small intestine. The liver secretes bile, which is stored in the gall bladder; this breaks down fats in the small intestine into smaller droplets in order to dissolve cholesterol. The small ...
This is a preview of the whole essay
After about three hours of chemical treatment in the stomach the food is reduced to a soft pulp called chyme and moves into the duodenum and then into the small intestine. The pancreas secretes pancreatic juice into the small intestine. The pancreatic juice contains enzymes that digest carbohydrates, proteins, and fats. The pancreatic juice also contains sodium bicarbonate, which neutralizes the hydrochloric acid in chyme protecting the small intestine. The liver secretes bile, which is stored in the gall bladder; this breaks down fats in the small intestine into smaller droplets in order to dissolve cholesterol. The small intestine is lined with finger like projections called villi; this increases the surface area of the lining of the small intestine, making absorption of nutrients more efficient. These nutrients are absorbed through capillaries and tiny lymph vessels called lacteals.
After absorption in the small intestine the undigested material moves into the large intestine. The large intestine absorbs water from the material remaining in the digestive tract. When most of the water has been removed from the undigested material, a solid waste matter, called feaces remains. Peristalsis propels the faeces through the large intestine into the rectum towards the end of the large intestine, which is then eliminated through the anus also known as defecation.
4) EXPLAIN THE ROLE OF THE LIVER IN ASSIMILATION OF A RANGE OF PRODUCTS OF DIGESTION AND EVALUATE THE NEED FOR SUCH A PROCESS.
According to Mullally (2002,p39), assimilation is "the process whereby the already digested foodstuffs are absorbed and utilized by the tissues". The liver is an example of organs that form or function in the process of assimilation of various digestive products. To explain this I will be highlighting the anatomy of the liver.
The liver is the largest organ in the body, which is divided by the falciform ligament into two lobes with the left lobe smaller than the right. The lobes are further more made up of smaller sections known as lobules, which are surrounded by hepatic arteries and portal veins The hepatic artery brings blood to the liver from the heart. This blood carries oxygen for the liver tissue itself as well as cholesterol and other substances for processing. Blood from the intestine and heart then mix together and flow back to the heart through the hepatic vein. The liver receives blood from both the intestine and the heart. Tiny capillaries in the intestinal wall drain the portal vein, which is rich in nutrients, and enters into the liver. The blood then flows through a latticework of channels inside the liver, where digested nutrients and any harmful substances or toxins are processed.
The liver performs many vital functions, from regulating the levels of chemicals in the body to producing substances that make the blood clot during bleeding, but the major function of the liver is to break down harmful substances absorbed from the intestine or elsewhere in the body, then excrete them as harmless by-products into the bile or the blood. These by-products are filtered out by the kidneys, which then leave the body in the urine.
It is now clear that the liver is responsible for many metabolic activities including the metabolism of protein, fats, and carbohydrates. However the liver also plays a role in digestion by secreting bile; bile is a yellowish-green liquid that hepatic cells secrete: it helps the digestion of fats, it is stored in the gallbladder. The liver sends bile to the small intestine. It is responsible for the elimination of certain waste products from the body particularly pigment from destroyed red blood cell and excess cholesterol and it assists in the digestion and absorption of fats.
ASSIMILATION OF CARBOHYDRATE-As indicated by Taylor et al (1997,p666), the liver receives all the food absorbed from the digestive tract to either convert or store them in various forms. Carbohydrate is part of the foods absorbed from the alimentary canal into the liver in the form of glucose. This "simple sugar" reaches the liver through the hepatic portal vein, once glucose is absorbed, the body uses up what it needs, and the liver makes this possible by orchestrating the level of glucose in the blood. This is achieved by converting glucose into glycogen or by mimicking the production of insulin, a hormone secreted by the pancreas. In addition, glucagons, a hormone also produced by the pancreas, influences the level of blood sugar as it responds to low sugar levels in the blood. This hormone breaks down glucagons into glucose, which is readily available. The process of glycogen-glucose conversion, which is influenced by the enzyme phosphorylase, is known as glycogenolysis. Glycogenolysis is also influenced by situations such as danger, stress, or cold due to the production of adrenaline. In instances where the balance between glucose and glycogen stored in the liver is exhausted, glucose is deprived from non-carbohydrate sources. This process occurs in response to reduced glucose levels in the blood. The liver also has the ability to convert carbohydrate that is not used or stored as glycogen into fat.
By regulating and metabolising carbohydrates, the liver aids the process of assimilation because it has the tendency to break down glycogen to be utilized or store excess carbohydrate as the case may be thus orchestrating how tissues or organs use this substance. This function, therefore, suggests that the absence of this organ will result into several complications such as hyperglycemia or hypoglycaemia shock respectively. Further more, the lack of this function or delay will present serious complications.
ASSIMILATION OF FAT - The liver also breaks down fat. In certain cases it helps to process it so that it becomes available to be used by the body tissues. The availability of fat is made through the conversion of excess carbohydrate to fat; the removal of cholesterol from blood and breaking it down or when necessary, synthesizing it. It has been suggested that this process is achieved when fats are broken down into fatty acids and glycerol through glycogenosis as previously described. In making fat ready for absorption, the product of the liver known as the bile, has to be secreted via the gall bladder. When the bile is produced in the liver, it is transferred to the gall bladder where it is stored and maintained. The secretion of a hormone known as cholecystokinin influences its release. Once stimulated the bile salt is released into the duodenum. The released bile salt contains substances such as cholesterol and phospholipids in the form of unicelles, which decrease surfaces tension of lipids to enable fat droplets emulsification by separating lipid molecules. Once this is achieved, an enzyme; pancreatic lipase, converts lipids into glycerol and fatty acids which is readily absorbed from the guts. Through these actions, the liver acts to produce and process fat so that it can be utilized or stored. This suggests that the absence or over and under production of the enzymes can be devastating because concentration of cholesterol may occur and this could have major implications on the gall bladder as it forms gall stones. This may result in the blockage of the bile duct causing severe discomfort.
5) ANALYSE EFFECTIVELY DIETARY INFORMATION (DATA) AND IDENTIFY AND EXPLAIN THE CONSEQUENCES OF DIETARY PROBLEMS.
What nutrients do we find in food?
All food contains a mixture of different nutrients. These are carbohydrates, proteins, fats, vitamins, minerals, fibre and water. Carbohydrates, proteins and fats are needed in larger amounts than vitamins, minerals, fibre and water. They are all very important in keeping our bodies normal and working properly.
Food can be divided into two main groups, organic and inorganic.
ORGANIC NUTRIENTS:
Fats, protein, carbohydrate and fibre are organic substances. These are made by living organisms.
INORGANIC NUTRIENTS:
Vitamins, minerals and water form this group. They are mostly found in other foods such as fruits and vegetables.
Proteins, carbohydrates, fats and fibre are measured in grams because they make up the largest portion of the cereal. Mineral and vitamins are usually only found in small amounts and so are measured in milligrams.
Carbohydrates
Carbohydrates can be grouped into starch, sugars and cellulose. Cereals, potatoes, rice and bread are high in starch, while table sugar, sweets and biscuits contain a lot of sugar. Carbohydrates give us energy, so we call it an energy food.
The body only needs a certain amount of carbohydrates to keep us alive. If we eat more than our body needs it will store it as fat on the hips, the stomach and the legs to be used later. We will not be able to look our favourite programs in certain cases as we use energy to look and blink our eyes. Thinking, walking, working and other daily activities will be hampered if we have less carbohydrate intake as this food give energy to carry out most daily activities including digestion as well. Too much of sugar for example results in tooth decay and overweight.
Fats
Milk, cheese, butter, egg yolk and fatty meat are examples of animal fat. Oils in fruits and seeds are plant fats and are used for cooking and making margarine.
There is an easy way to differentiate between a fat and oil. Fats are always hard at room temperature and burn very quickly when used during cooking. Oils are liquid at room temperature and have low melting points. Fats give twice as much energy as carbohydrates and are used to build cell membranes. Fats are also stored in the body and used for reserve energy. They help keep the body warm and protect delicate organs. Fats are also important in your diet because they contain fat-soluble vitamins. Fats must be broken down into simpler substances called fatty acids and glycerol. Fatigue will set in if this food substance is lacking or deficient. Indeed there will be problems with insulation and protection of certain organs for example the outer part of the kidney. However, too much of this affects the heart and circulatory system as fat clogs up in arteries and veins which will lead to heart attack.
Proteins
Beans, lentils (dhal), wheat and maize are the best source of plant protein. Animals provide the main source of proteins in a human diet. Lean meat, fish, milk and cheese are all examples of animal proteins. Proteins form the building blocks of body tissues Proteins are large molecules of single amino acids units. They must be broken down into these units (amino acids) to be absorbed into the blood stream. Deficiency in this nutrient results in retarded growth and reduced or no tissue repair, which means in cases of wounds, there will be delayed wound healing. If there is not enough protein is a child's diet they could suffer from a protein-deficiency disease called Kwashiorkor.
Fibre
Fibre, known as cellulose is found in the plant cell walls. Animals are not able to digest cellulose, so it has no nutritional value but to act as roughage to keep our digestive systems healthy by keeping our digestive tracts moving regularly. In adequate amounts results in constipation and difficulties in bowel movement. Eating more therefore reduces chances of obesity, which is caused by fat and carbohydrates (high amounts).
VITAMINS
Vitamins are chemical compounds found in food. Animals get vitamins, needed in small quantities from fresh vegetables. A disease caused by lack of vitamins is called a deficiency disease. Vitamins are named by letters A, B, C, D etc.
Vitamins are important because they help increase the body's resistance to infections. Overcooking destroys vitamins. Vitamin A helps the eye to see in dim lights. Therefore a deficiency in this results in night blindness and dry skin. Carrot is an example of the source this vitamin can be derived from. Vitamin B plays major role in cellular respiration and therefore, inadequate amounts results in nerve and heart disorders, loss of appetite, swelling of joints and blotchy and scaly skin. Vitamin C keeps our gums and teeth health. Insufficient amount results in scurvy-bleeding teeth and gums.
The body needs minerals for building tissues and other reactions. Some are needed in large amounts and others in small amounts. Most minerals come from the soil and are returned by different recycling processes. Some important minerals needed by animals are;
. Calcium-makes healthy bones, therefore deficiency could result in fragile bones.
2. Sodium-regulates water levels in our system. Inadequate amounts results in muscle cramps.
3. Iron-helps red blood cells to transport oxygen to our system. Anaemia as a result of deficiency occurs thus impairing oxygen transportation to the body.
WATER
Water is essential to life. Here are a few reasons why:
* Most of the cytoplasm is made up of water.
* It makes up 70% or more of living matter
* It is needed to split large molecules into smaller units.
* All chemical reactions take place in water.
* It helps move food and unabsorbed wastes in the intestines.
Therefore, inadequate amount of this nutrient results in slow processes within the body. Indeed, our cells loose turgidity and hence, solution properties changes result in flaccidity and confusion.
To prevent such problems occurring, we need a balanced diet each day. For normal health and growth a diet including the correct proportions proteins, vitamins, carbohydrates, mineral salts lipids and water are important. A diet including these foods is known as a balanced diet. A balanced diet can vary. Growing children need more proteins than adults do, males need more food than females, and labourers need more energy food while Eskimos need more fat in their diet to keep them warm. To keep healthy we must always eat the correct portions of various food groups;
* Energy foods like carbohydrates e.g. starches about 60%
* Fats, at least half of plant origin about 20%
* Protein about 25%
* We must also include foods high in vitamins and minerals. The food must be cooked properly so as not to destroy the vitamins in them.
* We should also drink at least 6-8 glasses of water a day.
6) IDENTIFY THE SOURCES AND TYPES OF MATERIALS EXCRETED AND EXPLAIN THE NEED FOR EXCRETION.
Excretion is a process whereby metabolic wastes are removed from the body. These include by-products of digestions; waste materials from tissue repair and excess water and salts, carbon dioxide from respiration and nitrogenous compounds from the break down of proteins and urea. Several organs of the body play major role in the process of excretion. Organs such as the kidneys, skin, liver and the large intestine play vital role in the excretion of a range of body wastes. The need for excretion is essential otherwise our body becomes toxic which could result in death.
The kidneys excrete excess nitrogenous substance in the urine in the form of urea. Urea contains uric acid, water and creatin. It is produced in the liver; which removes excess amino acids and is, then transported from the liver to the kidney in solution in blood plasma; the kidney then removes the urea from the blood and excretes it. The kidneys also excrete excess water, salts, some acids and some drugs. The kidney plays major role in the process of maintaining blood pressure and PH, and electrolytes balance. In addition, failure to excrete certain substances including inadequate electrolyte balance will lead to increase respiratory rate, blood pressure, heart failure and eventually death. Swelling may also occur in the system.
The skin: in the process of temperature regulation, sweat glands secrete salt and water on to the surface of the skin. In doing so, the skin helps regulate electrolyte balance and the removal of excess water form the system.
The Liver: Urea is a nitrogenous product made by the liver. Nitrogenous Wastes are initially brought to the liver as ammonia, and it could be harmful to cells if left in the body. It also excretes a substance called the bile, which consists of waste products and bile pigments from the breakdown of red blood cells. Some of this substance is passed in to the intestine and excreted as faeces.
The large intestine: excretes undigested foods, salts and excess water in the form of faeces.
The Lungs: excretes gas like carbon dioxide not needed by the body. This is achieved when blood-containing waste gases travels to the lungs through veins. While doing this the lungs simultaneously expel water vapour. If too much of carbon dioxide is left in the system, this could results in hypercarpnia, which is characterized by very red pigmentation on the skin. This condition progresses to respiratory acidosis.
7) ANALYSE THE ROLE OF THE LIVER IN DEALING WITH NITROGENOUS WASTES, CONSIDERING AND EXPLAINING THE VARIOUS OPTIONS.
Part of the liver's main function is the detoxification of both poisonous chemicals and substances that have potential toxic effects. Protein is an example of such substances that form a toxic substance known as urea. This process is initiated when excess amino acid in the body cannot be stored and is unwanted. Amino acids are groups of chemical compounds that form basic structural units of protein. The unwanted amino acid or those that are not needed for immediate protein synthesis or the formation of sugar are secreted by the kidney as urea. The process starts in the liver in several stages; deamination, transmission, and plasma protein production.
According to Mullally (2002,p18} deamination involves the removal of amino groups (NH2) from organic compounds such as amino acids. This suggests that the process results in the liver being able to produce non-essential amino acids and urea. Urea is a nitrogenous waste substance of humans. This substance is safe when deamination occurs because it is non-toxic, very soluble and is made up of smaller molecules. The formation of urea starts when amino acids further break down into less acidic substances like ammonia, which can be converted into nitrogen-containing compounds such as urea or uric acid
Ammonia is toxic in its initial state and therefore has to be eliminated. Its make up, solubility advocates for its rapid removal from the system in a safe manner once diluted in sufficient water.
In transmission, amino groups synthesis amino acids, to another organic acid as described by Taylor et al (1997,p668). This process produces amino acids that are deficient in diet.
During plasma protein production-albumen, globulin and gamma globulin, which are present in the blood and produced by lymphocytes and other immune cells, play vital role in homeostasis. These proteins carry certain substances while responding to immune stressors. These actions aid the metabolism of protein. Once urea is formed, the blood flows towards the afferent arteriole of the functional unit of the kidney, the nephrone, which filters the blood and finally excretes all waste and unwanted materials as urine. However, the skin during sweating also looses some amount of urea. It can be seen then that absence of the such function will lead to serious toxification of the system and hence electrolyte imbalances which might lead to confusion and when worsen result in death. Possible options to be explained where the liver presents problems, is abstinence from eating protein rich food and the reduction of potentials for toxification.
8) IDENTIFY THE VARIOUS PARTS OF THE KIDNEY (AT A GROSS AND MICROSCOPIC LEVEL) AND EXPLAIN THE FUNCTIONS AND ACTIONS OF THE VARIOUS PARTS.
The kidneys are two bean-shaped organs and is situated on each side of the spinal cord near the lower back and protected by the ribs. The kidney is composed of an outer layer, the cortex, and an inner core, the medulla. It also consists of repeating units (tubules) called nephrons. The "tops" of these nephrons make up or are in the cortex, while their long tubule portions make up the medulla. Each nephron has a closely associated blood supply. Blood comes in at the glomerulus and transfers water and solutes to the nephron at the Bowman's capsule. In the proximal tubule, water and some "good" molecules are absorbed back into the body, while a few other, unwanted molecules or ions are added to the urine. Then, the filtrate goes down the loop of henle. In the proximal tubule, water and some "good" molecules are absorbed back into the body, while a few other, unwanted molecules are added to the urine. Henle (in the medulla) where more water is removed (back into the bloodstream) on the way "down", but the "up" side is impervious to water. Some NaCl (salt) is removed from the filtrate at this point to adjust the amount in the fluid, which surrounds the tubule. Capillaries wind around and exchange materials with the tubule. In the distal tubule, more water and some "good" solutes are removed from the urine, while some more unwanted molecules are put in. From there, the urine flows down a collecting duct, which gathers urine from several nephrons. As the collecting duct goes back through the medulla, more water is removed from the urine. The collecting ducts eventually end up at the renal pelvis, which collects the urine from all of them.
Diagram of the Kidney
Josephine Swaray
