Respiratory System PDF

Respiratory system introduction We will be talking about: 1- Organs that make up the respiratory system. 2- The anatomy and histology of the respiratory system 3-Processes of Respiration (Internal and External respiration). 4- Process of Ventilation. 5- Gas exchange and where it occurs. 6- Transpor...

Respiratory system introduction We will be talking about: 1- Organs that make up the respiratory system. 2- The anatomy and histology of the respiratory system 3-Processes of Respiration (Internal and External respiration). 4- Process of Ventilation. 5- Gas exchange and where it occurs. 6- Transport of gases by blood. 7- the diseases. Main Parts Of The Human Respiratory System In the human thorax, the following can be found: Air Pathway Anatomy: Anatomy: Nose Lungs Pharynx Ribs & Intercostal Muscles Larynx Pleural Muscles Trachea Diaphragm Bronchi The organs that make the respiratory system  Nose Nasal cavity Naso-pharynx Larynx Trachea Bronchus Bronchioles Alveolar ducts Alveoli(air sacs)  The nose: Each nasal cavity is bounded by a wall of spongy bone, hyaline cartilage and skeletal muscle. The nasal cavity includes the respiratory area which is present in the posterior part of the nasal cavity; it’s covered by pseudo-compound ciliated epithelium with goblet cells. Cilia from pseudo compound ciliated epithelium, and mucus from the goblet cells are along the inside wall of the nasal cavity trap and they remove dust and pathogens from the air which flows through the nasal cavity. Also the cilia moves mucus down the nasal cavity to the pharynx where it can be swallowed. Anatomy of the nose  Looks like a pyramid. The nasal cavity is divided into two nasal passages. Nasal passages are covered by a moist mucous membrane. Air, as it passes, is made moist & warm to protect the lungs from the harmful effects of dry air. Fine hairs filter the dust particles present in the air. Functions of the Nose:- Provides an airway for respiration. Moistens and warms entering air. Filters and cleans inspired air. Resonating chamber for speech. Detects odor in the air stream. pharynx Pharynx The pharynx is one of the organs found in the respiratory system. The pharynx is part of the throat located behind the mouth and nasal cavity BUT above the esophagus and larynx. It is found in both vertebrates and invertebrates however the structure is not the same. It connects the nasal cavity with the larynx. Its surface is lined with pseudo compound ciliated with goblet cells. It is 2 to 3 cm wide and 3 to 4 cm long. It provides a passage for air during breathing. The nasopharynx remains open even when surrounding muscles flex so that the person can continue to carry on respiratory functions. Anatomy of the pharynx The Nasopharynx The nasopharynx is the upper part of the throat behind the nose. It is a part of the pharynx, which comprises three sections: 1. Nasopharynx 2. Oropharynx 3. Hypopharynx larynx  larynx The larynx, commonly called the voice box, is an organ found in the neck. The larynx houses the coal folds (vocal cords), which are essential for phonation. The vocal folds are situated just below where the tract of the pharynx splits into the trachea and the esophagus.  Larynx function:- The larynx connects the pharynx with the trachea. It has two functions:- 1. Prevention of food and fluid from entering the respiratory passages. 2. Production of voice (the larynx is also known as the voice box.) The larynx is formed by elastic cartilage also the epiglottis. The larynx is lined with pseudo-compound ciliated epithelium with goblet cells in between , except the vocal chords and the anterior surface of the epiglottis which are covered only with compound squamous epithelium. Trachea Trachea It is formed of a tube about 20 cm long. It is divided below into two primary bronchi. It is kept open all the time because of the presence of about 20 c-shaped or incomplete rings of hyaline cartilage of its wall. It is incomplete ring of hyaline because this allows the trachea to collapse slightly to allow food to pass down the esophagus. The trachea is lined with pseudo compound ciliated cells. Functions of Trachea Provides a clear airway for air to enter and exit the lungs. The epithelium lining the trachea produces mucus that traps dust and other contaminants and prevents it from reaching the lungs. Cilia moves the mucus towards the pharynx where it can be swallowed and digested in the gastrointestinal tract. Bronchi  Bronchi The trachea (windpipe) conducts inhaled air into the lungs through its tubular branches, called bronchi. The bronchi then divides into smaller and smaller branches (bronchioles), finally becoming microscopic. The bronchioles eventually end in clusters of microscopic air sacs called alveoli. Anatomy of the Bronchi  Primary bronchi are located in the upper portion of the lungs, with secondary bronchi near the center of the lungs. Tertiary bronchi are located near the bottom of these organs, just above the bronchioles. No gas exchanges occur in any of the bronchi. Function The main function of the bronchi and bronchioles is to carry air from the trachea into the lungs. Smooth muscle tissue in their walls helps to regulate airflow into the lungs. The bronchi and bronchioles use the mucus and cilia of their epithelial lining to trap and move dust and other contaminants away from the lungs. The lung  Lungs  The human lungs are the main organs of the respiratory system.  They are a pair of large, spongy organs.  Responsible for gas exchange between our blood and the air. There are two lungs each one is present at one side in the thoracic cavity. The right lung has three lobes, while the left lung has two lobes. Each lung is formed of bronchial tree, alveolar ducts, alveoli, blood vessels. The alveoli are the primary site of gases exchange with the blood. The lung contains about 300,000,000 alveoli. Each lung is formed of : Bronchial tree Alveolar ducts Alveoli ( about 300 millions for gases exchange with the blood) Blood vessels Lung Anatomy Lungs Location: In the thoracic cavity. Function: where gases exchange with the blood. The right lung has 3 lobes whereas the left lung has 2 lobes. The lobes are filled with small, spongy sacs called alveoli. The lungs’ tissue surface is almost 40 times greater than the body’s outer surface, making the lungs one of the largest organs in the body. Alveoli  Alveoli are the functional units of the lungs that permit gas exchange between the air in the lungs and the blood in the capillaries of the lungs. Each alveolus is a hollow, cup-shaped cavity surrounded by many tiny capillaries. alveoli At the end of each alveolar duct there are a number of sac-like structures called alveoli, it is within these structures that surfactant is produced.(Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid) The alveoli are grouped together like a lot of interlinked caves, rather than existing as separate individual sacs. Structure and Function  Gas exchange of oxygen and carbon dioxide takes place in the alveoli. Oxygen from the inhaled air diffuses through the walls of the alveoli and adjacent capillaries into the red blood cells. The oxygen is then carried by the blood to the body tissues. Carbon dioxide produced by the body’s metabolism returns to the lung via the blood. It then diffuses across the capillary and alveolar walls into the air to be removed from the body with expiration. The alveoli have a structure specialized for efficient gaseous exchange: Walls are extremely thin. They have a large surface area in relation to volume. They are fluid lined enabling gases to dissolve. They are surrounded by numerous capillaries. Ribs:- Function: To protect lungs, solidify thoracic region and to aid ventilation. The intercostal muscles are a group of 22 pairs of tiny muscles found between the ribs. The 22 pairs of intercostal muscles are broken down into two groups: 11 pairs of internal intercostal and 11 pairs of external intercostal. Diaphragm Function: Controls breathing, separates the chest cavity from the abdominal cavity. The diaphragm is a dome-shaped muscle at the bottom of the lungs. Openings in the diaphragm allow the esophagus, nerves, descending aorta, and inferior vena cava to pass between the thoracic and abdominal cavities. 1. Nose Each nasal cavity is bounded by a wall of: Spongy bone Hyaline cartilage Skeletal muscle The nasal cavity includes the respiratory area. This is present in the posterior part of the nasal cavity. It is covered by pseudo-stratified (compound) ciliated epithelium with goblet cells.  2-Larynx The Larynx is made up of elastic cartilage. There are nine cartilages, three unpaired and three paired, that support the mammalian larynx and form its skeleton. Paired Cartilages: Arytenoid cartilages: Of the paired cartilages, the arytenoid cartilages are the most important because they influence the position and tension of the vocal folds. These are triangular pieces of mostly hyaline cartilage located at the posterior superior border of the cricoid cartilage. Corniculate cartilages: Horn-shaped pieces of elastic cartilage located at the apex of each arytenoid cartilage. Cuneiform cartilages: Club-shaped pieces of elastic cartilages located anterior to the corniculate cartilages. Unpaired cartilages: Thyroid cartilage: This forms the Adam’s apple. It is usually larger in males than in females. The thyrohyoid membrane is a ligament associated with the thyroid cartilage that connects the thyroid cartilage with the hyoid bone. Cricoid cartilage: A ring of hyaline cartilage that forms the inferior of the larynx. It is attached to the top of trachea. The median cricothyroid ligament connects the cricoid cartilage to the thyroid cartilage. Epiglottis: A large, spoon-shaped piece of elastic cartilage. During swallowing, the pharynx and larynx rise. Elevation of the pharynx widens it to receive food and drink; elevation of the larynx causes the epiglottis to move down and form a lid over the glottis, closing it off.  The muscles of the larynx are divided into intrinsic and extrinsic muscles. The intrinsic laryngeal muscles are responsible for controlling sound and production. The extrinsic laryngeal muscles support and position the larynx within the trachea. 3-Trachea  It’s lined with pseudo compound ciliated epithelial cells.  Made of incomplete rings of hyaline cartilage. respiration Respiration. There are two processes of respiration: 1. Internal or Cellular Respiration 2. External Respiration 1. Internal or Cellular Respiration Location: Mitochondria in cells. Main function: To release energy. Aerobic Respiration: It requires oxygen and it releases lots of energy. C6H12O6 + 6O2 6H2O + 6CO2 + ATP Anaerobic Respiration: It does not require oxygen but releases much less energy in comparison. C6H12O6 lactic acid + ATP During these 2 process ATP is formed, which is then broken down and hydrolyzed to form ADP + phosphoric acid, and energy is given out. 2. External Respiration Is simply the process of ventilation. Main and only function is to take in oxygen from the air and return carbon dioxide. Ventilation Ventilation The human respiratory system consists of a tube leading from the nose and mouth down to two lungs. The lungs have millions of specialized cells called alveoli. These cells filter oxygen from the air to directly provide to the blood. This is possible because of the tiny blood vessels called capillaries that surround the alveoli. The process of ventilation is divided into two parts: inhaling and exhaling. Inhalation: It is the intake of air through the change of pressure and volume due to the movement of muscles (intercostal muscles, the diaphragm) and the movement of the rib cage. The diaphragm relaxes and goes downwards, and the inner intercostal relaxes and the outer intercostal muscles contract, the ribcage goes outwards and upwards to increase the volume of the lungs, decreasing the pressure inside the lungs, making air (gas) move from a region of high pressure (atmosphere) to a region of low pressure… and that is the process of inhalation. Exhalation: It’s the process of releasing air (gas) inside the lungs to the atmosphere… The diaphragm contracts and goes upwards, decreasing the volume of the lungs, and the inner intercostal contracts and the outer intercostal muscles relaxes, the ribcage goes inwards and downwards to (decreasing the volume of the lungs, increasing the pressure inside the lungs) this causes air to leave the lungs going back to the atmosphere. Breathing is controlled by the expansion and contraction of the diaphragm. This dome-shaped muscle is located below the lungs, and it compresses and expands the lungs to make the body perform the subconscious reflex of breathing. The diaphragm does this about 12 to 20 times every minute, changing according to what an individual is doing. People in a state of panic might hyperventilate, or breathe much faster than normal, in an effort to introduce more oxygen to the blood in an emergency. This biological reflex is one of the few that can be consciously controlled. Anyone hyperventilating can calm themselves down by forcing more measured breathing. Alveoli and Gas Exchange  Air enters the body through the nose is warmed filtered and passed through the nasal cavity. Air passes the pharynx. The upper part of the trachea contains the larynx after passing the larynx the air moves into the bronchi that carries air in and out of the lungs. Bronchi are rein enforced to prevent their collapse and are lined with ciliated epithelial and mucous producing cells. Bronchi branch into smaller and smaller tubes known as bronchioles. Bronchioles terminate into grape like sac cluster known as alveoli. Alveoli are surrounded by a network of thin walled capillaries (to complete the respiration process) Transport of gases by blood  Transport of oxygen by the blood At rest, the cells of a human needs about 50,000,000 of oxygen per minute. After oxygen enters the blood capillaries in the lungs it diffuses into the red blood cells and unites with the respiratory pigment known as haemoglobin in the form:- Hb+O2 HbO2 The arrow indicates that the reaction is reversible, in other words it can go in either direction. In the lungs the reaction goes to the right from oxyhaemoglobin, and in the tissues, it goes to the left releasing O. 2.  This process is controlled by two factors: (1) The amount of oxygen present. (2) A lower extent of the amount of carbon dioxide. In the lungs the concentration of the oxygen is relatively high and thus the oxyhaemoglobin is formed. In the tissues, the oxygen is little and accordingly oxyhaemoglobin breaks down releasing oxygen to diffuse to the tissue cells.  As regards that carbon dioxide reacts with water forming the carbonic acid (H CO ) and so an increase in CO 2 3 2 increases the acidity of the blood and accordingly decreases the oxygen carrying the capacity of the haemoglobin. Oxygen (O ) released from haemoglobin by combined 2 effect of low oxygen tension and high carbon dioxide tension. Transport of carbon dioxide(CO ) by the blood. 2 Some carbon dioxide is carried in loose chemical union with haemoglobin as carbaminhaemoglobin and small amount is present as carbonic acid,H CO ,but most of the latter is converted 2 3 into bicarbonates of sodium or potassium. Carbon dioxide passes from tissues to the blood and from the blood to the lungs by simple diffusion from a region of high tension to a region of low tension.  The process of converting carbon dioxide into carbonic acid in the capillaries of the tissues and of converting carbonic acid into carbon dioxide in the lung capillaries is catalyzed (speeds up) by an enzyme called carbonic anhyrase. Notice: All veins inside the body takes deoxygenated blood except pulmonary vein. All arteries inside the body take oxygenated blood except for the pulmonary artery. Diseases of Respiratory System The most common problems of the respiratory system are: Emphysema: Long-term smoking often causes emphysema. In emphysema, the lungs produce an excessive amount of mucus and the alveoli become damaged. It becomes difficult to breathe and get enough oxygen into the blood.  Lung cancer: Caused by an abnormal growth of cells in the lungs, lung cancer is usually caused by smoking cigarettes. It starts in the lining of the bronchi and takes a long time to develop, so it's generally a disease in adults. Symptoms include a persistent cough that may bring up blood, chest pain, hoarseness, and shortness of breath.  Asthma: Asthma is a chronic inflammatory lung disease that causes airways to tighten and narrow. This narrowing of the airways prevents air from flowing properly, causing difficulty breathing, sometimes to the point of being life-threatening. Management of asthma starts with an asthma management plan, which usually involves avoiding asthma triggers and sometimes taking medications.  Bronchitis In bronchitis, which is a common disease of adults and teens, the membranes lining the larger bronchial tubes become inflamed and an excessive amount of mucus is produced. The person develops a bad cough to get rid of the mucus. Cigarette smoking is a major cause of chronic bronchitis in teens.