1.2.1. Anatomy notions of the respiratory system
The respiratory system is made of all the organs which contribute to the gas exchange between the organism and the environment. This system extracts the oxygen from the air and eliminates the carbon dioxide from the organism. In addition, this system gives the perception of smell (upper side of the nasal cavity) and achieves the phonatory function-speech (larynx, vocal cords).
The respiratory system consists of:
- the respiratory tract through which the air enters and exits the organism
- the lungs are the organs which perform the gas exchange.
The respiratory tract consists of superior respiratory tract and inferior respiratory tract.
The superior respiratory tract consists of the nasal cavity and the pharynx and the inferior tract consists of the larynx, trachea and bronchi.
The nasal cavity is the first segment of the respiratory tract and is divided by the nasal septum into two cavities named fossae. The nasal fossae are covered with a moist mucous membrane, which warms the air. Also here there is the mucus, which plays a part in retaining the impurities in the air. So, the nose has the role of a filter.
The pharynx is an organ common to both the respiratory tract and the digestive tract.
The larynx is the speech organ, is made of multiple mobile cartilages, the largest one being situated in front like a prominece shaped as an open book. In the larynx can be found two pairs of folds named vocal cords; the inferior ones are responsible for the sounds we make.
The trachea continues the larynx and is situated in front of the oesophagus. It splits at it's inferior level into two branches which are called main bronchi.
The bronchi are the last segments of the respiratory tract and each of them enters a lung.
The lungs are pair organs situated into the thoracic cavity and hold between them the heart.
Breathing
The air enters the lungs through the respiratory tract due to the contraction of the thoracic muscles, named respiratory muscles. This is the inspiration act. Then the respiratory muscles relax and the expiratory muscles contract; therefore part of the air in the lungs is expelled; this is the exiration act. The inspiration and the expiration repeat with a rhythm of 14-18/minute, depending on the organism needs. This rythm varies according to age and sex (is more accelerated in women and children).
Normal respiratory rythm values:
- New-born = 40/min
- Children = 20 - 30/min
- Adults = 14 - 18/min
The measurement of the respiratory frequence is made during one minute, holding the hand on the patient's chest, counting the thoracic expansions without letting the patient be aware of the procedure.
1.2.2. Anatomy notions of the circulatory system
The cardio-circulatory system is made of a central organ - the heart - and a closed system of vessels, made of arteries - capillaries - veins.
The heart is a muscular organ weighting approximatively 300 grams with a volume which has been compared to the volume of the right fist of an adult.
It consists of two completely separate halfs, the left one and the right one, separated by a vertival wall. Each half is split by a transversal wall into two chambers, which communicate with each other. The chambers in the upper side are called auricles, and those in the lower side are called ventricles.
The circulatory system is made of arteries, capillaries and veins.
The arteries are blood vessels through which the blood circulates from the heart to the entire organism. The calibre of the arteries decreases from the heart towards the periphery.
The veins are blood vessels which bring the blood to the heart. Their calibre increases from the periphery to the heart.
The capillaries are small calibre vessels, through which the nourishing exchange is made between the blood and the cells. The blood circulates only one way: arteries - capillaries - veins.
The arteries and the veins have different names, depending on the region and the organ they irrigate.
In the structure of the circulatory system there are:
- the large circulation
- the small circulation
The large circulation transports oxygen towards the tissues and the organs, brings CO2 from the tissues and the organs towards the heart, having the path: heart - arteries - organs - veins - heart.
The small circulation provides the transport of unoxygenated blood from the heart towards the lungs and of the oxygenated blood from the lungs to the heart.
The blood circulation through the arteries is made by the pushing of the blood due to the contraction of the ventricles. The blood is pushed intermittently, but it flows continously due to the elasticity of the arterial walls. The arterial walls oppose resistance which makes the blood to flow under a certain pressure. This is called blood pressure (BP). So, the blood pressure represents the pressure the blood exercises on the arterial walls.
The BP varies depending on age, sex, time of day and degree of activity.
Normal values:
- Adult: 115-140 / 70-90 mmHg, lower in women.
- Child 91-110 / 60-65 mmHg.
Values over the normal ones are called hypertension.
Values below the normal ones are called hypotension.
Systole=contraction, diastole=relaxation.
The measurement of the BP:
- patient's position: dorsal decubit, after a rest of 10 minutes;
- at the inferior third of the arm is placed the tensiometer's sleeve;
- the stethoscope is placed on the projection of the brachial artery (inferior margin of the arm);
- the tensiometer's sleeve is filled up to 180/ 200 mmHg, and then the air is slowly released;
- the values of the BP are the first and last heartbeat that can be heard in the stethoscope during the release of the air;
With every heart contraction a quantity of blood is pushed into the aorta, which pushes the blood existent in the vessel and propagates like a wave, generating the pulse.
The pulse can be measured by compressing an artery on a bone, with 2-3 fingers, the most frequently at the radial artery; it is counted for a minute.
Normal values:
- adults 60-80 / minut;
- children 90-100 / minut;
- new-born 130-140 / minut;
The increase of the frequency over the normal values is called tachycardia, the decrease below the normal values is called bradycardia.
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