The Cardiovascular System:
The circulatory system transports and supplies oxygen to the cells in the body. The cells require
oxygen to survive, oxygen is supplied as most cells do not have direct contact. The circulatory system
also supplies the body with nutrients and energy. When the food is digested it travels through the
intestines and is absorbed into the bloodstream along with glucose from the liver. The blood also
absorbs waste matter and transports them to excretory organs. The blood also transports cells that
fight disease, these are created by organs in the immune system. The cardiovascular system is also
responsible for the transportation of hormones produced in a singular location within the body and
then transported to another. The circulatory system also aids in the regulation of body temperature.
If the temperature becomes too low, the blood vessels would constrict, the smaller surface area of
blood vessels would cause less heat to escape, conserving more body heat.
The Respiratory System:
Inhalation and exhalation (pulmonary ventilation), air is inhaled and through the nose and mouth
(nasal and oral cavities) and travelling through to the lungs (via the pharynx, larynx and trachea). The
air is the exhaled as carbon dioxide through the same pathway. The respiratory system is also
responsible for phonation. Phonation is the creation of sound in the respiratory tract. Whilst
exhaling the air moves through the larynx and when we speak the muscles move the arytenoid
cartilages. These cartilages push the vocal cords towards each other, air passing through at this time
causes sound.
The Digestive System:
The mouth is where the digestive process begins. The smell of food triggers the secretion of saliva,
which contains salivary amylase enzyme aiding in the disintegration of starch. The pharynx then
passes chewed food into the oesophagus. Food is passed from the hypo-pharynx to the oropharynx.
Food is converted into small masses and moved into the stomach. The cardiac sphincter closes the
end of the oesophagus trapping food in the stomach. This is a process called peristalsis. Food is
coated with digestive enzymes and acids in the stomach, helping to disintegrate food. The walls of
the stomach are protected against the acid by thick mucus. The digested food is then passed on to
the small intestine. The small intestine is in three separate parts (duodenum, jejunum and ileum).
The walls of the small intestine have villi which help to absorb nutrients into the bloodstream. In the
duodenum, fats, proteins and carbohydrates are broken down using enzymes provided by the
pancreas. Bile is provided from the gall bladder to aid in the breaking down of fats the body can use.
Next is the large intestine which absorbs water and disintegrates any waste. Once nutrients have
been extracted the matter will become faeces, which will be excreted through the anal canal.
The Renal System:
The renal system are organs that produce, store and release urine. The kidneys are located in the
back cavity of the abdominal cavity, one on either side. The kidney transports urine into the ureters
previous to its exit from the body. The bladder is situated in the pelvic area, its function being the
collection and storage of the urine that has exited the kidneys. When the bladder become full it exits
into the ureters leaving the bladder. The ureters are tubes made from muscle and attached to both
the kidneys and bladder. They use only a small amount of pressure to push urine from the kidneys
and into the bladder, and then into the urethra on its way to exit the body. The ureters also prevent
the urine from travelling back into the kidneys, a condition known as reflux. The urethra is the last
destination for the urine, it is a hollow tube connected to the bladder exiting through the genitals.
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