Human Respitary Organs

NOTE 1 : HUMAN RESPITARY ORGANS The human respiratory system includes all the structures that connect air to and from the lungs. The main respiratory organs are the lungs. You can understand the respiratory organs in humans by studying the following material. a. Nose The nose functions as a respiratory organ and sense of smell. The nose consists of the nostrils, nasal cavity, and tip of the nasal cavity. The nasal cavity has hair, lots of blood capillaries, and is always moist with mucus produced by the mucous membrane.In the nasal cavity, the air is filtered by small hairs (cilia) and mucous membranes which are useful for filtering dust, attaching dirt to nasal hair, regulating the temperature of the breathing air, and detecting the presence of odors. At the base of the oral cavity, which is connected to the nasal cavity, there is a valve called the pharynx. When a child swallows food, the throat will rise upwards to cover the nasal cavity so that food cannot enter the nasal cavity. b. Pharynx The pharynx is the junction for air and food. The pharynx is the junction between the mouth cavity to the esophagus and the nose to the throat. c. Larynx The larynx is also called the base of the throat or voice box.The larynx consists of cartilage that forms the Adam's apple.The Adam's apple is composed of the tongue bone, cartilage valve, cartilage shield, cartilage cup, and cartilage ring.The base of the throat can be closed by the larynx valve (epiglottis). When swallowing food, the epiglottis folds down to cover the larynx so that food cannot enter the larynx. Meanwhile, when you breathe, the epiglottis opens. At the base of the throat there are vocal membranes or better known as vocal cords. d. Trachea The trachea (windpipe) is a pipe that is approximately 9 cm long. The trachea is composed of sixteen to twenty C-shaped cartilage rings. These cartilage rings are not connected at the back, namely where the trachea attaches to the esophagus. This is useful for keeping the trachea open.The cartilage rings are held together by fibrous tissue, while there is also some muscle tissue.The trachea is lined by a mucous membrane produced by ciliated epithelium. These cilia move upwards towards the larynx so that with this movement dust and other fine particles that enter when inhaling can be expelled.In the lungs, the trachea branches into two bronchi. e. Bronchi The bronchi are a pair of branches of the windpipe, one leading to the right lung and the other leading to the left lung. This branching site is called a bifurcation. The bronchi have a similar structure to the trachea and are lined with the same types of cells. The bronchus to the left is longer and narrower and has a more horizontal position than the one to the right. This is one of the reasons why the right lung is more susceptible to disease. The right bronchus branches into three bronchioles, while the left bronchus branches into two bronchioles. f. Bronchioles Bronchioles are branches of the bronchi, their walls are thinner and the tubes are smaller. The smaller the canal, the less cartilage it has and ultimately only a fibrous wall with a layer of cilia remains. Each terminal (last) bronchiole opens into a tuft of small grape-like sacs called alveoli. g. Alveoli The alveolus is the final channel of the respiratory system in the form of air bubbles. The walls are thin, moist, and tightly adherent to blood capillaries.The alveoli consist of a single layer of flat epithelial cells and this is where the blood comes into almost direct contact with the air. The presence of alveoli allows for the expansion of the surface area which plays an important role in the exchange of O2 gas from free air to blood cells and CO2 h. Lungs There are two lungs and are the main respiratory organs. The lungs are located in the chest cavity. They are located on the right and left and in the middle are separated by the heart. Lung tissue has elastic, porous and sponge-like properties. When placed in water, the lungs will float because they contain air in them.The lungs are divided into several hemispheres or lobes.The right lung has three lobes and the left lung has two lobes. Each lobe is composed of lobules. The lungs are lined by a membrane or double serous membrane called the pleura. Between the two layers of the pleura there is exudate to oil the surface thereby preventing friction between the lungs and the chest wall which moves when breathing. In a healthy condition the two layers are in close contact with each other. However, in abnormal circumstances, air or fluid separates the two pleura and the space between them becomes clear.The pressure in the pleural or intrathoracic cavity is smaller than the outside air pressure (± 3–4 mmHg). In the inside of the lungs there are fine bubbles which are extensions of the surface of the lungs called alveoli and there are approximately 300 million of them. With the presence of alveoli, the surface area of the lungs is estimated to reach 160 m2 or 100 times larger than the surface area of the body.