Medical Surgical Nursing 2
Date: November 6, 2012
Name: Judine Douglas
The primary function of the respiratory system is to supply the blood with oxygen in order for the blood to deliver oxygen to all parts of the body. The respiratory system does this through breathing. When we breathe, we inhale oxygen and exhale carbon dioxide. This exchange of gases is the respiratory system's means of getting oxygen to the blood.
What makes up the Respiratory System?
The human respiratory system consists of the nose, nasal cavity, pharynx, larynx, trachea, smaller conducting passageways (bronchi and bronchioles), and lungs.
The Nose or Nasal Cavity
As air passes through the nasal cavities it is warmed and humidified, so that air that reaches the lungs is warmed and moist. The Nasal airways are lined with cilia and kept moist by mucous secretions. The moisture in the nose helps to heat the air, increasing the amount of water vapour the air entering the lungs contains. This helps to keep the air entering the nose from drying out the lungs and other parts of our respiratory system. When air enters the respiratory system through the mouth, much less filtering is done. It is generally better to take in air through the nose. The Pharynx
The pharynx is also called the throat. Below the epiglottis is the larynx or voice box. This contains 2 vocal cords, which vibrate when air passes by them. With our tongue and lips we convert these vibrations into speech. The area at the top of the trachea, which contains the larynx, is called the glottis. The Trachea
The trachea or windpipe is made of muscle and elastic fibres with rings of cartilage. The cartilage prevents the tubes of the trachea from collapsing. The trachea is divided or branched into bronchi and then into smaller bronchioles. The bronchioles branch off into alveoli. These tubes are lined with mucous-secreting cells and tiny hairs called cilia. The mucous traps bacteria, dust and viruses. The cilia beat and create an upward current. This moves the mucous up and into the oesophagus. Here it goes to the stomach. When we clear our throats we force the mucous away from our vocal cords. This is often called coughing. It is used to get rid of irritants and excess mucous from our respiratory system. Gas Exchange
Body cells use the inhaled oxygen gotten from the alveoli of the lungs. In turn, they produce carbon dioxide and water, which is taken to the alveoli and then exhaled. These exchanges occur as a result of diffusion. In each case the materials move from an area of high concentration to an area of lower concentration. The alveoli are well suited for the important job they have. There are about 300,000,000 alveoli per lung! That means there is a great surface area for gas exchange. Also, the walls of the alveoli as well as the capillaries are very thin so that the gases can diffuse readily. When the blood picks up the diffused gases the gases are carried to their destinations. Most of the oxygen is carried by the haemoglobin in the red blood cells with only a small % dissolved in the plasma. Carbon dioxide and water are carried in the plasma of the blood. The Mechanism of Breathing
Inspiration or inhalation is said to be an active process because it involves muscle contraction. The contracting diaphragm flattens and stretches the elastic lungs downward. The contracting intercostals pull the ribcage up and out causing the elastic lungs to stretch. The expanding lungs cause the air inside to expand (a gas will always fill its container). The expansion of air causes a drop in air pressure in the lungs. The air in the lungs is at a lower pressure than the air outside. Air flows from higher to lower pressure so air flows into the lungs from outside. Expiration or exhalation is said to be a passive process because it does not involve muscle contraction. The diaphragm and the intercostal muscles relax. The...