According to Wright (2007), we need energy for everything we do. Energy can be found in different forms including chemical energy, electrical energy, thermal energy, radiant energy, mechanical energy and nuclear energy. We use energy all the time including when we are sleeping. We use energy for our muscle activity, new cells and blood circulation. (Wright, 2007) We get energy from the foods that we eat. Metabolism is a chemical activity which uses cellular respiration. (Wright, 2007) Aerobic respiration is respiration with oxygen present. (Wright, 2007) The formula for cellular respiration is below: Glucose +oxygen = Energy, carbon dioxide and water. Carbon dioxide and water are the waste products from creating energy.
Respiration can happen without oxygen. This process is called anaerobic respiration. The equation glucose+ oxygen which produces energy along with the bi-products produces 38 Adenosine Triphosphate (ATP). It produces more ATP because it has oxygen present (aerobic) this is used more effectively in the body for things like growing. The rest is wasted through heat as a bi-product which can be good as we need to stay warm. ATP is the unit for measuring energy. Respiration without oxygen produces 2 ATP so the energy is not as efficient as there is not as much ATP being produced. Whereas from the equation where oxygen is present, it produces 38 ATP which is more efficient which is used for activities like movement. (Khan Academy, 2009) You can then proceed to the below equation is an example of anaerobic respiration: Glucose =lactic acid +energy.
Aerobic respiration happens in the mitochondria whereas anaerobic respiration occurs within the cytoplasm. (Wright, 2007) Metabolic rate is the amount of energy used in a certain period of time. This energy is from the nutrients found in food. (Biology, 2010) Cellular respiration can be further broken down into three different stages. There are three stages of the process of cellular respiration these are Glycolysis, Krebs cycle and Electron transport chain. (About, n.d) The first stage of cellular respiration is glycolysis. Glycolysis is the breakdown of glucose. We get glucose from the carbohydrates we eat and are digested through the digestion system. (About, n.d) The digestive system is there to digest the food we eat.
Through the digestive system carbohydrates get transformed into disaccharides then into a monosaccharide which is also known as glucose. We use the glucose to make energy which is used in aerobic respiration. (About, n.d) The digestive system starts with the mouth. In the mouth is where mechanical digestion happens. Mastication means that food is mechanically broken down in the mouth. Mastication is another term used for chewing; this is the first stage of digestion. Digestion happens through a number of different processes. Within the mouth, food is broken down by an enzyme called salivary amylase. The salivary amylase is produce and comes from the salivary gland. From masticating the food, the amylase breaks down the carbohydrates into disaccharides. Disaccharides are 2 molecules from the carbohydrate which have been broken down.
A bolus is made from mastication and the food is shaped into a ball as it is easier to swallow. (Enzymes, 2005) Next the foods go down the oesophagus. Movement of the bolus (food) breaks down further. This is because there is still a bit of salivary amylase going down the oesophagus with the food. (Enzymes, 2005) After going down the oesophagus the food reaches the stomach. The food stays in the stomach for 60 minutes until it is digested further by stomach acid and pepsin. Pepsin is an enzyme which is released within the stomach. (Enzymes, 2005) “Your stomach lining also secretes hydrochloric acid, which creates the ideal conditions for the protein-digesting enzymes to work.” The stomach produces hydrochloric acid; this is to kill the bacteria within the food. (BBC Science, n.d) Our stomach enzymes neutralises the hydrochloric acid by secreting sticky mucus which clings to the stomach walls. If this becomes damaged then this can cause stomach ulcers.
This means that the food turns to chyme. (BBC Science, n.d) The chyme next enters the small intestine. The small intestine is split up into three sections. The first part of the small intestine is called duodenum, then the jejunum and then the ileum. The duodenum helps to break down the disaccharides. The enzyme which helps to break down the disaccharides is called pancreatic amylase which is produced from the pancreas. Then the food goes through to the jejunum which helps to break down the disaccharides into monosaccharides. This is glucose now. This is broken down by the enzymes which are released from the pancreas and liver. Monosaccharaides is a molecule which only has one link left, this one link is also known as a sugar or glucose and proteins are broken down into amino acids. (Knoji, n.d)
During this, glucose can be taken through the small intestine just like oxygen is through the alveoli. Glucose is absorbed through the wall and is collected when the blood stream passes adjacent to it. There is glucose left in the duodenum. Inside the duodenum is the microvilli which increases the surface area. The blood travels from the Aorta and the blood will go through the duodenum. Glucose is absorbed through the wall and is collected when the blood stream which passes adjacent to it. Glucose moves around the blood as a free plasma molecule. (About, n.d) The ileum absorbs vitamin B-12, bile and salt. The bile is absorbed and then returned back to the liver. The ileum also has the lymphatic tissue on the outside which identifies and destroys harmful microorganisms. (Knoji, n.d) Glucose molecule is C6 H12 O6
Glycolysis breaks the glucose from a 6 carbon molecule into 2 times 3 carbon molecules in the cytoplasm. Glycolysis breaks down glucose with anaerobic respiration; this means that the process does not require oxygen. Glucose produces 4 ATP but the anaerobic process requires 2 ATP. This leaves the body plus 2 ATPs. This process is not a productive step as not loads of energy is being made. (About, n.d) The next step of cellular respiration is the Krebs cycle. The Krebs cycle happens after the glycolysis has broken down the module into two sections of three sugars. The Krebs cycle requires 2 ATP for to process to work. Oxygen and glucose move throughout the body by the blood transport system. From this the oxygen and glucose reach the mitochondria cells for the Krebs cycle. Krebs cycle requires oxygen which is aerobic respiration. Krebs cycle provides electrons and hydrogen needed for electron transport chain. This process happens within the mitochondria membrane.
The Krebs cycle can only happen when oxygen is present. (About, n.d) When oxygen is present oxygen and glucose enters the Krebs cycle, this is done by entering the mitochondria matrix. This gets oxidized to carbon dioxide which is used for the electron transport chain. (About, n.d) The oxygen which is around our body is provided from the respiratory system. We need to breath in oxygen and breathe out carbon dioxide; this is also known as ventilation. We breathe in oxygen from two places the oral cavity (Mouth) and Nasal cavity (nose) which are both connected at the back to the pharynx. The pharynx is then split into two the back links to the oesophagus for our food and the front is your larynx which is for air. You will also find your voice box in your larynx. (Khan Academy, 2010) The air travels down the larynx to the trachea. The trachea also splits into two. These are called bronchi. The bronchi split off into smaller bronchioles. (Khan Academy, 2010)This is shown in figure 1. Figure 1 Figure 2
These bronchioles are found in both of the lungs which end up going to air sacks called alveoli. The alveoli are thin membranes. These membranes are 1/5 of an mm each one. The thin membranes are surrounded by blood vessels. (Khan Academy, 2010)These are shown in figure 2. Within the pulmonary circulation the arteries go away from the heart with deoxygenated blood whereas veins go towards the heart with oxygenated blood. Oxygen passes through the capillaries and goes into the bloodstream. There are pulmonary arteries and veins which mean they go to the lungs. Arteries release carbon dioxide. (Khan Academy, 2010)
Our diaphragm is a muscle. As we breathe in oxygen our diaphragm causes movement which expands and bends downwards which pulls the lungs down allowing our lungs to fill up with more oxygen. This is also known as negative pressure as is sucks down the oxygen into the lungs like a vacuum. And when we breathe out our diaphragm is relaxed and the pressure is raised for exhalation which we breathe out carbon dioxide. (Khan Academy, 2010) When oxygen moves into the alveoli, it is then diffused from the alveoli which are located into the lungs and into the pulmonary vein where it then goes towards the heart. This is oxygenated blood traveling to the heart. There is a chamber in the heart called the aorta, this lets the blood travel around the body and when it reaches the side of the duodenum, collects the glucose through from the microvilli as mentioned and then the blood carries on travelling around the body. (About, n.d) Oxygen does not travel as a molecule otherwise it will make the blood syrup thickness. Therefore the blood is packaged into haemoglobin, which is inside the red blood cells.
These are shaped as a disk with a dip in the middle; this allows as much oxygen as possible to travel. These cells turn red when they are oxygenated and blue when they are deoxygenated. (About, n.d) Lastly after Krebs cycle is the electron transport chain. This process also requires oxygen to process. The electron transport chain is a link of electrons which takes place in the membrane within the mitochondria. These electrons have high energy with an ATP at about 34. These electrons end up being passed onto the oxygen. The electron transport chain produces a bulk of energy using aerobic respiration. (About, n.d) Overall the body produces 38 ATP but during the process of glycolysis and Krebs cycle they each use up 2 ATP which leaves the body with 34 ATP. (About, n.d)
To complete I have explained how the respiratory and digestive system work and throughout the systems discussed the role of energy in the body. I have discussed what energy is and how energy is used in the role of the respiratory and digestive system.
About (n.d) Cellular respiration, website, available at:
http://biology.about.com/od/cellularprocesses/a/cellrespiration.htm [Accessed on 5/2/14] BBC Science (n.d) Organs-stomach, website, available at:
http://www.bbc.co.uk/science/humanbody/body/factfiles/stomach/stomach.shtml [Accessed on 28/2/14] Biology (2010) Metabolic rate, website, available at:
http://www.biology-online.org/dictionary/Metabolic_Rate [Accessed on 29/1/14] Enzymes (2005) Digestion, website, available at:
http://www.enzymestuff.com/digestion.htm [Accessed on 28/2/14] Khan Academy (2010) You Tube the lungs and pulmonary system, website, available at: http://www.youtube.com/watch?v=SPGRkexI_cs [Accessed on 29/1/14] Kid port (2012) Digestion and digestive system, website, available at: http://www.kidport.com/reflib/science/HumanBody/DigestiveSystem/Digestion.htm [Accessed on 29/1/14] Knoji (n.d) Human body: jejunum and ileum, website, available at: http://gastrointestinal-conditions.knoji.com/human-body-jejunum-and-ileum/ [Accessed on 28/2/14] Wright, D (2007) Human Physiology and Health, Oxford: Heinemann
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