The heart is a double pump each side consist a muscular upper and lower chamber. The right side of the heart pumps deoxygenated blood from the vein to the lungs for oxygenation. However, the left side pumps oxygenated blood from the lung to the body. These two sides are separated by septum. The blood passes twice through the heart in only one cycle. This is known as "double circulation".
Aldworth,C Et Al, 2010, EDEXCEL BTEC Level 3 Health and Social Care, Book 1, page 199.
The pulmonary circulation
The circulation to and from the lungs is known as the ‘Pulmonary circulation’ and that around the body is the systemic circulation.
In the pulmonary circulation, the pulmonary artery carrying deoxygenated blood leaves the right ventricle to go to the lungs and enters the left atrium.
However, the main artery to the body leaving the left ventricle is the aorta, whereas the main vein bringing blood back to the heart from the body enters the right atrium which is also known as the vena cava.
The vena cava has two branches, which are: the superior, which returns blood from the head and neck. The second branch is the inferior vena cava which returns blood from the rest of the body.
In addition, the pulmonary and the aorta also have exits that are protected by valves called semi-lunar valves. These valves are vital for the pulmonary circulation. It is vital, since the blood has to go in one direction; the blood has been forced into the arteries by the ventricular muscle contractions it must not be allowed to fall back into the ventricular when they relax which are named pulmonary and aortic valves.
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The cardiac cycle
Lastly, the cardiac cycle encompasses the events taking place within the heart during one heartbeat.
The events in which the cardiac cycle can be described are as follows:
- Both atria contract, forcing blood under pressure in the ventricles.
- Ventricles are bulging with blood and the increased pressure forces the atrio-ventricular valves shut
- Muscles in the ventricular walls begin to contract, pressure on blood inside rises and forces open the semi-lunar valves in the aorta and pulmonary artery.
- Ventricular systole forces blood into the aorta on the left side and pulmonary artery on the right side. These arteries have elastic walls and begin to expand.
- As the blood leaves the ventricles, the muscles starts to relax. For a fraction of a second blood falls backwards, catching the pockets of the semi-lunar valves and making them close.
- With the ventricles in a diastole, the atrio-ventricular valves are pushed open with the blood that has been filling the atria. When the ventricles are about 70% full, the atria contract to push the remaining blood in swiftly and the next cycle has begun.
When the chambers are in a diastole and relaxed, they are still filling. The heart never goes empty of blood, due to it being a continuous cycle. With a high heart rate, it is the filling time that has been shortened.
The Digestive system
Food is taken into the mouth and is mixed with saliva. It is then masticated by the tongue and teeth and is rolled into a small ball which is known as a bolus and swallowed. This is an important part of breaking the food down as it must be done at an early stage. This process is called mechanical digestion. However, if the food is not broken down properly the individual can choke which could lead to fatal reactions.
The Salivary Glands
There are three pairs of salivary glands. The Salivary glands pour their secretions which are also known as the saliva into the mouth. Saliva is a digestive juice that contains enzymes which are called salivary amylase which begins to digest sugars as well as make the mouth smooth and help the bolus formation.
The Oesophagus
The oesophagus which is also known as the gullet which transports the food bolus from the back of the mouth and into the stomach. The swallowed bolus remains in the gullet for only a few seconds. The gullet is mainly a transit for food boluses. It moves by muscular slimming down known as peristalsis. http://www.umm.edu/graphics/images/en/8710.jpg
The Stomach
The stomach is the broadest part of the nutrient canal, which is tucked mainly behind the rib cage under the diaphragm which is located on the left side. Food can stay in the stomach for up to three hours; however, a protein meal persists in the stomach for the longest while food that doesn’t contain protein passes through rapidly. The stomach glands produce a liquid that contains gastric protease and hydrochloric acid. The gastric liquid works on proteins. The epithelial lining of the stomach contains goblet cells, which produce thick mucus to protect the lining from acid erosion.
The Liver
The liver is a large dark red organ that vacates on the top right half of the abdomen and is incompletely overlapping the stomach. The liver has numerous important functions in the body. One of the functions is to produce bile. Bile flows down the bile duct into the duodenum, after temporary storage in the gall bladder on the below surface of the liver. Bile contains no enzymes, yet, it provides imperative bile salts which lead to the emulsification of fat which is also known as lipids in the duodenum.
Emulsification results in the fats forming millions of tiny globules, each with a water/lipid surface so that enzymes can work efficiently over massively enlarged area.
The liver removes glucose and other sugars from the blood coming from the small intestine and converts them into glycogen for storage.
Energy laws
Energy is what we need to in order to anything, as mentioned before. The first law of thermodynamics also known as the management of energy. Energy is can be transformed however cannot be created or destroyed. The first part of this decree refers to the transformation of energy from one form in to another. Whereas, the second form may not be of use or be capable or being measured.
Forms of energy
Energy can be present in several forms. Chemical energy is the most common. The energy is in the chemical bond that unites atoms or molecules with each other. When a new bond is made amongst two atoms, energy is necessary for its establishment. This is usually in the form of heat, although light and electrical energy can be used. However, when a bond is broken and atoms are released, the energy in the bond is unconfined as well.
Other methods of energy are heat, light, sound, electrical and nuclear.
Energy metabolism and the role of energy in the body
At this stage, you be wondering why there is a considerable amount of emphasis on energy related to muscular activity and movement. Nevertheless, energy is also needed to circulate blood. Lymph and tissue fluid throughout the body. Energy is also needed for breathing, taking in oxygen, making new cells, carrying out growth and repair and to transmit nerve impulses so that we can respond to changes in the environment. Lastly, energy is needed to build different complex molecules such as enzymes and hormones from the simple molecules produced after digestion of food.
Anabolism and catabolism
Catabolic reaction is responsible for the chemical reaction of breaking down molecules. The oxidation of glucose inside cells are a catabolic reaction, yet there are many more. However, the opposite process is building complex molecules from simple substances and using energy, the name for this is Anabolic reaction.
Reference
Resource: Aldworth,C Et Al, 2010, EDEXCEL BTEC Level 3 Health and Social Care, Book 1,Pearson Education Limited
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omzie (student)
