Respiratory System PDF

 The respiratory system supplies the blood with oxygen so that the blood can deliver oxygen to all parts of the body. And also removes carbon dioxide waste that cells produce. Oversees gas exchanges between the blood and external environment Exchange of gasses takes place within the al...

 The respiratory system supplies the blood with oxygen so that the blood can deliver oxygen to all parts of the body. And also removes carbon dioxide waste that cells produce. Oversees gas exchanges between the blood and external environment Exchange of gasses takes place within the alveoli Passageways to the lungs purify, warm, and humidify the incoming air  UPPER LOWER RESPIRATORY RESPIRATORY TRACT TRACT Nasal cavity Trachea Pharynx Bronchi Epiglottis Lungs Larynx Diaphragm  UPPER RESPIRATORY TRACT Nasal cavity Pharynx Epiglottis Larynx  LOWER RESPIRATORY TRACT Trachea Bronchi Lungs Diaphragm  Breathing consists of two cyclic phases: ○ Inhalation, also called inspiration - draws gases into the lungs. ○ Exhalation, also called expiration - forces gases out of the lungs. Nasal cavity - Pharynx - Epiglottis - Larynx  Olfactory receptors are located in the mucosa on the superior surface The rest of the cavity is lined with respiratory mucosa ○ Moistens air ○ Traps incoming foreign particles Lateral walls have projections called conchae ○ Increases surface area ○ Increases air turbulence within the nasal cavity The nasal cavity is separated from the oral cavity by the palate ○ Anterior hard palate (bone) ○ Posterior soft palate (muscle)  The only externally visible part of the respiratory system Air enters the nose through the external nares (nostrils) The interior of the nose consists of a nasal cavity divided by a nasal septum Contains cilia which is responsible for filtering out foreign bodies. Function of the Nose Provides an airway for respiration Moistens and warms entering air Filters and cleans inspired air Resonating chamber for speech detects odors in the air stream  Cavities within bones surrounding the nasal cavity ○ Frontal bone ○ Sphenoid bone ○ Ethmoid bone ○ Maxillary bone Function of the sinuses Lighten the skull Act as resonance chambers for speech Produce mucus that drains into the nasal cavity Produce mucus that drains into the nasal cavity  Muscular passage from nasal cavity to larynx Three regions of the pharynx ○ Nasopharynx – superior region behind nasal cavity ○ Oropharynx – middle region behind mouth ○ Laryngopharynx or hypopharynx – inferior region attached to larynx  The oropharynx and laryngopharynx are common passageways for air and food Auditory tubes enter the nasopharynx Tonsils of the pharynx ○ Pharyngeal tonsil (adenoids) in the nasopharynx ○ Palatine tonsils in the oropharynx ○ Lingual tonsils at the base of the tongue It is a flap made of cartilage that closes the air tube when you swallow. Thus, it prevents the entry of food to the trachea that leads to the lungs.  Routes air and food into proper channels Plays a role in speech Made of eight rigid hyaline cartilages and a spoon-shaped flap of elastic cartilage (epiglottis) Vocal cords - vibrate with expelled air to create sound (speech)  Thyroid cartilage ○ Largest hyaline cartilage ○ Protrudes anteriorly (Adam’s apple) Epiglottis ○ Superior opening of the larynx ○ Routes food to the larynx and air toward the trachea Glottis – opening between vocal cords Trachea - Bronchi - Lungs - Diaphragm  Connects larynx with bronchi Lined with ciliated mucosa ○ Beat continuously in the opposite direction of incoming air ○ Expel mucus loaded with dust and other debris away from lungs Walls are reinforced with C-shaped hyaline cartilage  Formed by division of the trachea Enters the lung at the hilus (medial depression) Right bronchus is wider, shorter, and straighter than left Bronchi subdivide into smaller and smaller branches  Bronchioles are air passages inside the lungs that branch off like tree limbs from the bronchi—the two main air passages into which air flows from the trachea (windpipe) after being inhaled through the nose or mouth. The bronchioles deliver air to tiny sacs called alveoli where oxygen and carbon dioxide are exchanged.  Smallest branches of the bronchi All but the smallest branches have reinforcing cartilage Terminal bronchioles end in alveoli  Structure of alveoli ○ Alveolar duct ○ Alveolar sac ○ Alveolus Gas exchange takes place within the alveoli in the respiratory membrane Squamous epithelial lining alveolar walls Covered with pulmonary capillaries on external surfaces  Occupy most of the thoracic cavity ○ Apex is near the clavicle (superior portion) ○ Each lung is divided into lobes by fissures Left lung – two lobes Right lung – three lobes  is a thin double-membrane that provides fluid which allows the lungs to move and slide freely as they contract and expand during breathing Pulmonary (visceral) pleura covers the lung surface Parietal pleura lines the walls of the thoracic cavity Pleural fluid fills the area between layers of pleura to allow gliding  The diaphragm is the primary muscle used in respiration, which is the process of breathing. This dome-shaped muscle is located just below the lungs and heart. It contracts continually as you breathe in and out. HOW DO WE BREATH?  Lungs are sealed in pleural membranes inside the chest cavity. At the bottom of the cavity is a large, flat muscle known as the diaphragm. During inhalation, the diaphragm contracts and the rib cage rises up. This expands the volume of the chest cavity.  The chest cavity is sealed, so this creates a partial vacuum inside the cavity. Atmospheric pressure fills the lungs as air rushes into the breathing passages. Often exhaling is a passive event. When the rib cage lowers and the diaphragm relaxes, pressure in the chest cavity is greater than atmospheric pressure. Air is pushed out of the lungs.  Air enters your lungs through a system of pipes called the bronchi. The alveoli are where the important work of gas exchange takes place between the air and your blood. Covering each alveolus is a whole network of little blood vessel called capillaries, It is important that the air in the alveoli and the blood in the capillaries are very close together, so that oxygen and carbon dioxide can move (or diffuse) between them.  When you breathe in, air comes down the trachea and through the bronchi into the alveoli. This fresh air has lots of oxygen in it, and some of this oxygen will travel across the walls of the alveoli into your bloodstream. Travelling in the opposite direction is carbon dioxide, which crosses from the blood in the capillaries into the air in the alveoli and is then breathed out. In this way, you bring in to your body the oxygen that you need to live, and get rid of the waste product carbon dioxide.  Gas crosses the respiratory membrane by diffusion ○ Oxygen enters the blood ○ Carbon dioxide enters the alveoli Macrophages add protection Surfactant coats gas-exposed alveolar surfaces  Pulmonary ventilation – moving air in and out of the lungs External respiration – gas exchange between pulmonary blood and alveoli Respiratory gas transport – transport of oxygen and carbon dioxide via the bloodstream Internal respiration – gas exchange between blood and tissue cells in systemic capillaries  Oxygen movement into the blood ○ The alveoli always has more oxygen than the blood ○ Oxygen moves by diffusion towards the area of lower concentration ○ Pulmonary capillary blood gains oxygen Carbon dioxide movement out of the blood ○ Blood returning from tissues has higher concentrations of carbon dioxide than air in the alveoli ○ Pulmonary capillary blood gives up carbon dioxide Blood leaving the lungs is oxygen-rich and carbon dioxide-poor  Oxygen transport in the blood ○ Inside red blood cells attached to hemoglobin (oxyhemoglobin [HbO2]) ○ A small amount is carried dissolved in the plasma Carbon dioxide transport in the blood ○ Most is transported in the plasma as bicarbonate ion (HCO3–) ○ A small amount is carried inside red blood cells on hemoglobin, but at different binding sites than those of oxygen  Exchange of gases between blood and body cells An opposite reaction to what occurs in the lungs ○ Carbon dioxide diffuses out of tissue to blood ○ Oxygen diffuses from blood into tissue INSPIRATION - EXPIRATION  Mechanical process Depends on volume changes in the thoracic cavity Volume changes lead to pressure changes, which lead to equalize pressure of flow of gases 2 phases ○ Inspiration – flow of air into lung ○ Expiration – air leaving lung  Diaphragm and intercostal muscles contract The size of the thoracic cavity increases External air is pulled into the lungs due to an increase in intrapulmonary volume  Passive process dependent up on natural lung elasticity As muscles relax, air is pushed out of the lungs Forced expiration can occur mostly by contracting internal intercostal muscles to depress the rib cage  Normal pressure within the pleural space is always negative (intrapleural pressure) Differences in lung and pleural space pressures keep lungs from collapsing  Caused by reflexes or voluntary actions Examples ○ Cough and sneeze – clears lungs of debris ○ Laughing ○ Crying ○ Yawn ○ Hiccup  Caused by reflexes or voluntary actions Examples ○ Cough and sneeze – clears lungs of debris ○ Laughing ○ Crying ○ Yawn ○ Hiccup  Normal breathing moves about 500 ml of air with each breath - tidal volume (TV) Many factors that affect respiratory capacity ○ A person’s size ○ Sex ○ Age ○ Physical condition Residual volume of air – after exhalation, about 1200 ml of air remains in the lungs  Inspiratory reserve volume (IRV) ○ Amount of air that can be taken in forcibly over the tidal volume ○ Usually between 2100 and 3200 ml Expiratory reserve volume (ERV) ○ Amount of air that can be forcibly exhaled ○ Approximately 1200 ml Residual volume ○ Air remaining in lung after expiration ○ About 1200 ml  Sounds are monitored with a stethoscope Bronchial sounds – produced by air rushing through trachea and bronchi Vesicular breathing sounds – soft sounds of air filling alveoli  Chronic Obstructive Lung Cancer Pulmonary Disease Sudden Infant Death (COPD) Syndrome (SIDS) Emphysema Asthma Chronic Bronchitis  Exemplified by chronic bronchitis and emphysema Major causes of death and disability in the United States Features of these diseases ○ Patients have a history of smoking ○ Labored breathing (dyspnea) ○ Coughing and frequent pulmonary infections  Features of these diseases ○ Most victims retain carbon dioxide ○ Have hypoxia and respiratory acidosis ○ Those infected will ultimately develop respiratory failure  Alveoli enlarge as adjacent chambers break through Chronic inflammation promotes lung fibrosis Airways collapse during expiration Patients use a large amount of energy to exhale Over-inflation of the lungs leads to a barrel chest Cyanosis appears late in the disease  Inflammation of the mucosa of the lower respiratory passages Mucus production increases Pooled mucus impairs ventilation & gas exchange Risk of lung infection increases Pneumonia is common Hypoxia and cyanosis occur early  Accounts for 1/3 of all cancer deaths in the United States Increased incidence associated with smoking Three common types ○ Squamous cell carcinoma ○ Adenocarcinoma ○ Small cell carcinoma  Healthy infant stops breathing and dies during sleep Some cases are thought to be a problem of the neural respiratory control center 1/3 of cases appear to be due to heart rhythm abnormalities  Chronic inflammation if the bronchioles passages Response to irritants with dyspnea, coughing, and wheezing  Lungs are filled with fluid in the fetus Lungs are not fully inflated with air until two weeks after birth Surfactant that lowers alveolar surface tension is not present until late in fetal development and may not be present in premature babies Important birth defects ○ Cystic fibrosis – over-secretion of thick mucus clogs the respiratory system ○ Cleft palate  Elasticity of lungs decreases Respiration rate: Vital capacity decreases Newborns – 40 to 80 min. Blood oxygen levels Infants – 30 min. decrease Age 5 – 25 min. Stimulating effects of Adults – 12 to 18 min carbon dioxide decreases Rate often increases with More risks of respiratory old age tract infection NERVOUS SYSTEM