Ch 13 Respiratory System Lecture Packet PDF

**Key Words:** +-----------------------------------+-----------------------------------+ | Ventilation | Trachea | | | | | Sinus | Surfactant...

**Key Words:** +-----------------------------------+-----------------------------------+ | Ventilation | Trachea | | | | | Sinus | Surfactant | | | | | Bronchus | Alveolus | | | | | Respiratory membrane | External respiration | | | | | Diaphragm | Respiratory mucosa | | | | | Internal respiration | Pleura | | | | | Pharynx | | | | | | Larynx | | | | | | Diffusion | | +-----------------------------------+-----------------------------------+ **Learning Objectives:** After studying the material from this unit, the student should be able to: 1. Define and use key terminology related to the topics discussed. 2. Name the components of the respiratory system and describe their anatomical and physiological features. 3. Describe how air is modified as it enters the respiratory system. 4. Know the location and functions of the three regions of the pharynx. 5. Describe the structure and function of the epiglottis. 6. Describe and understand the gross and microscopic (alveolar) structure of the lungs. 7. Pulmonary Ventilation: - Describe the pressure and volume changes occurring in the thorax and lungs during the phases of pulmonary ventilation: expiration and inspiration. 8. Understand the neural regulation of respiration. 9. Understand the non-neural factors that affect respiration. 10. Describe alveolar gas exchange through the respiratory membrane. Note the structure of this membrane. 11. Describe the make-up and function of surfactant. 12. Define and discuss the process of internal respiration and external respiration 13. Know the respiratory disorders along with the signs and symptoms of each one. Chapter 13 ========== The Respiratory System ====================== Organs of the Respiratory System ================================ Nose ---- Pharynx ------- Larynx ------ Trachea ------- Bronchi ------- Lungs---alveoli --------------- Functional Anatomy of the Respiratory System ============================================ Gas exchanges between the blood and external environment occur only in the alveoli of the lungs ----------------------------------------------------------------------------------------------- Upper respiratory tract includes passageways from the nose to larynx -------------------------------------------------------------------- Lower respiratory tract includes passageways from trachea to alveoli -------------------------------------------------------------------- ### Passageways to the lungs purify, humidify and warm the incoming air The Nose ======== The only externally visible part of the respiratory system ---------------------------------------------------------- ### Nostrils (nares) are the route through which air enters the nose ### Nasal cavity is the interior of the nose ### Nasal septum divides the nasal cavity The Nose ======== Olfactory receptors are in the mucosa on the superior surface ------------------------------------------------------------- The rest of the cavity is lined with respiratory mucosa, which -------------------------------------------------------------- ### Moistens air ### Traps incoming foreign particles ### Enzymes in the mucus destroy bacteria chemically The Nose ======== Conchae are projections from the lateral walls ---------------------------------------------- ### Increase surface area ### Increase air turbuluence within the nasal cavity. ### Turbulence causes the air to swirl and slow down so it can be purified, humidified, and warmed. {#turbulence-causes-the-air-to-swirl-and-slow-down-so-it-can-be-purified-humidified-and-warmed..ListParagraph} ### Increased trapping of inhaled particles The palate separates the nasal cavity from the oral cavity ---------------------------------------------------------- ### Hard palate is anterior and supported by bone ### Soft palate is posterior and unsupported Paranasal sinuses ----------------- ### Cavities within the frontal, sphenoid, ethmoid, and maxillary bones surrounding the nasal cavity ### Sinuses: #### lighten the skull #### Act as resonance chambers for speech #### Produce mucus The Pharynx =========== Commonly called the *throat* ---------------------------- Muscular passageway from nasal cavity to larynx ----------------------------------------------- Three regions of the pharynx ---------------------------- 1. ### Nasopharynx---superior region behind nasal cavity 2. ### Oropharynx---middle region behind mouth 3. ### Laryngopharynx---inferior region attached to larynx Oropharynx and laryngopharynx serve as common passageway for air and food ------------------------------------------------------------------------- ### Epiglottis routes food into the esophagus, keeps food and fluid from going down into your lungs. Pharyngotympanic tubes open into the nasopharynx ------------------------------------------------ ### Drain the middle ear {#section-1.ListParagraph} Tonsils are clusters of lymphatic tissue that play a role in protecting the body from infection ----------------------------------------------------------------------------------------------- ### Pharyngeal tonsil (adenoid), a single tonsil, is located in the nasopharynx ### Palatine tonsils (2) are located in the oropharynx at the end of the soft palate ### Lingual tonsils (2) are found at the base of the tongue The Larynx ========== Commonly called the *voice box* ------------------------------- Functions --------- ### Routes air and food into proper channels ### Plays a role in speech Located inferior to the pharynx ------------------------------- Made of eight rigid hyaline cartilages -------------------------------------- ### Thyroid cartilage (Adam's apple) Epiglottis ---------- ### Spoon-shaped flap of elastic cartilage ### Protects the superior opening of the larynx ### Routes food to the posteriorly situated esophagus and routes air toward the trachea ### During swallowing, the epiglottis rises and forms a lid over the opening of the larynx Vocal folds (true vocal cords) ------------------------------ ### Vibrate with expelled air ### Allow us to speak The glottis includes the vocal cords and the opening between the vocal cords ---------------------------------------------------------------------------- The Trachea =========== Commonly called the *windpipe* ------------------------------ 4-inch-long tube that connects to the larynx -------------------------------------------- Walls are reinforced with C-shaped rings of hyaline cartilage which keep the trachea patent (open) -------------------------------------------------------------------------------------------------- Lined with ciliated mucosa -------------------------- ### Cilia beat continuously in the opposite direction of incoming air ### Expel mucus loaded with dust and other debris away from lungs ### Cilia are damaged by smoking. This is why smokers tend to cough a lot. They must move the mucus up and away from the lungs on their own. It is often called the "Smoker's Cough" The Main Bronchi ================ Formed by division of the trachea --------------------------------- Each bronchus enters the lung at the hilum (medial depression) -------------------------------------------------------------- Right bronchus is wider shorter, and straighter than left --------------------------------------------------------- Bronchi subdivide into smaller and smaller branches --------------------------------------------------- The Lungs ========= Occupy the entire thoracic cavity except for the central *mediastinum* ---------------------------------------------------------------------- Apex of each lung is near the clavicle (superior portion) --------------------------------------------------------- Base rests on the diaphragm. ---------------------------- Each lung is divided into lobes by fissures ------------------------------------------- ### Left lung---two lobes ### Right lung three lobes Serosa covers the outer surface of the lungs -------------------------------------------- ### Pulmonary (visceral) pleura covers the lung surface ### Parietal pleura lines the walls of the thoracic cavity Pleural fluid fills the area between layers ------------------------------------------- ### Allows the lungs to glide over the thorax ### Decreases friction during breathing The bronchial tree ------------------ ### Main bronchi subdivide into smaller and smaller branches ### Bronchial (respiratory) tree is the network of branching passageways ### All but the smallest passageways have reinforcing cartilage in the walls ### Conduits to and from the respiratory zone ### Bronchioles (smallest conducting passageways) Respiratory Zone Structures and the Respiratory Membrane ======================================================== Terminal bronchioles lead into and terminate in alveoli ------------------------------------------------------- ### Alveoli (air sacs)---the only site of gas exchange Alveoli ------- ### Simple squamous epithelial cells largely compose the walls ### Alveolar pores connect neighboring air sacs Pulmonary capillaries cover external surfaces of alveoli -------------------------------------------------------- Respiratory membrane (air-blood barrier) ---------------------------------------- ### On one side of the membrane is air and on the other side is blood flowing past ### Air is on the inside of the alveoli and blood is inside the capillary. Therefor the respiratory membrane is formed by the alveolar and capillary walls. ### Formed by alveolar and capillary walls Gas crosses the respiratory membrane by diffusion ------------------------------------------------- ### Oxygen enters the blood ### Carbon dioxide enters the alveoli Alveolar macrophages ("dust cells") ----------------------------------- ### Add protection by picking up bacteria, carbon particles, and other debris Surfactant (a lipid molecule) ----------------------------- ### Coats gas-exposed alveolar surfaces ### Allows the alveoli to easily open and fill with air. Thus, helping with gas exchange. Functions of the respiratory system ----------------------------------- ### Supply the body with oxygen ### Dispose of carbon dioxide Respiration includes four distinct events (discussed next) ---------------------------------------------------------- ### Pulmonary ventilation ### External respiration ### Respiratory gas transport ### Internal respiration Respiratory Physiology ====================== Four events of respiration -------------------------- 1. ### Pulmonary ventilation---moving air into and out of the lungs (commonly called *breathing*) 2. ### External respiration---gas exchange between pulmonary blood and alveoli #### Oxygen is loaded into the blood #### Carbon dioxide is unloaded from the blood {#section-3.ListParagraph} 3. ### Respiratory gas transport---transport of oxygen and carbon dioxide via the bloodstream 4. ### Internal respiration---gas exchange between blood and tissue cells in systemic capillaries Mechanics of Breathing ====================== Pulmonary ventilation --------------------- ### Mechanical process that depends on volume changes in the thoracic cavity ### Volume changes lead to pressure changes, which lead to the flow of gases to equalize pressure Mechanics of Breathing (continued) ================================== Two phases of pulmonary ventilation ----------------------------------- ### Inspiration = inhalation #### Flow of air into lungs ### Expiration = exhalation #### Air leaving lungs Inspiration (inhalation) ------------------------ ### Diaphragm and external intercostal muscles contract ### Intrapulmonary volume *increases* ### Gas pressure *decreases* ### Air flows into the lungs until intrapulmonary pressure equals atmospheric pressure Expiration (exhalation) ----------------------- ### Largely a passive process that depends on natural lung elasticity ### Intrapulmonary volume *decreases* ### Gas pressure *increases* ### Gases passively flow out to equalize the pressure ### Forced expiration can occur mostly by contraction of internal intercostal muscles to depress the rib cage Intrapleural pressure --------------------- ### The pressure within the pleural space) is *always* negative ### Major factor preventing lung collapse ### If intrapleural pressure equals atmospheric pressure, the lungs recoil and collapse Respiratory Volumes and Capacities ================================== Factors affecting respiratory capacity -------------------------------------- ### Size ### Sex ### Age ### Physical condition Respiratory Volumes and Capacities ================================== Residual volume --------------- ### Air remaining in lung after expiration ### Cannot be voluntarily exhaled ### Allows gas exchange to go on continuously, even between breaths, and helps keep alveoli open (inflated) Respiratory capacities are measured with a spirometer ----------------------------------------------------- Nonrespiratory Air Movements ============================ Can be caused by reflexes or voluntary actions ---------------------------------------------- Examples -------- ### Cough and sneeze---clears lungs of debris ### Crying---emotionally induced mechanism ### Laughing---similar to crying ### Hiccup---sudden inspirations ### Yawn---very deep inspiration External Respiration, Gas Transport, and Internal Respiration ============================================================= Gas exchanges occur as a result of diffusion -------------------------------------------- ### External respiration is an exchange of gases occurring between the alveoli and pulmonary blood (pulmonary gas exchange) ### Internal respiration is an exchange of gases occurring between the blood and tissue cells (systemic capillary gas exchange) Movement of the gas is toward the area of lower concentration ------------------------------------------------------------- Oxygen is loaded into the blood ------------------------------- ### Oxygen diffuses from the oxygen-rich air of the alveoli to the oxygen-poor blood of the pulmonary capillaries Carbon dioxide is unloaded out of the blood ------------------------------------------- ### Carbon dioxide diffuses from the blood of the pulmonary capillaries to the alveoli Gas Transport the Blood ======================= Oxygen transport in the blood ----------------------------- ### Most oxygen travels attached to hemoglobin and forms oxyhemoglobin (HbO~2~) ### A small dissolved amount is carried in the plasma Gas Transport in the Blood (continued) ====================================== Carbon dioxide transport in the blood ------------------------------------- ### Most carbon dioxide is transported in the plasma as bicarbonate ion (HCO~3~^--^) ### A small amount is carried inside red blood cells on hemoglobin, but at different binding sites from those of oxygen For carbon dioxide to diffuse out of blood into the alveoli, it must be released from its bicarbonate form: ----------------------------------------------------------------------------------------------------------- ### Bicarbonate ions enter RBC ### Combine with hydrogen ions ### Form carbonic acid (H~2~CO~3~) ### Carbonic acid splits to form water + CO~2~ ### Carbon dioxide diffuses from blood into alveoli Internal Respiration ==================== Exchange of gases between blood and tissue cells ------------------------------------------------ An opposite reaction from what occurs in the lungs -------------------------------------------------- ### Carbon dioxide diffuses out of tissue cells to blood (called ***loading*)** ### Oxygen diffuses from blood into tissue (called ***unloading*)** Control of Respiration ====================== Neural regulation: setting the basic rhythm ------------------------------------------- ### Activity of respiratory muscles is transmitted to and from the brain by phrenic and intercostal nerves ### Neural centers that control rate and depth are located in the medulla and pons #### Medulla---sets basic rhythm of breathing and contains a pacemaker (self-exciting inspiratory center) called the *ventral respiratory group (VRG)* #### Pons- smooths out respiratory rate Normal respiratory rate (eupnea) -------------------------------- ### 12 to 15 respirations per minute Hyperpnea --------- ### Increased respiratory rate, often due to extra oxygen needs Non-neural factors influencing respiratory rate and depth --------------------------------------------------------- ### Physical factors #### Increased body temperature #### Exercise #### Talking #### Coughing ### Volition (conscious control) ### Emotional factors such as fear, anger, and excitement Non-neural factors influencing respiratory rate and depth (continued) --------------------------------------------------------------------- ### Chemical factors: CO~2~ levels #### The body's need to rid itself of co2 is the *most* important stimulus for breathing #### Increased levels of carbon dioxide (and thus, a decreased or acidic pH) in the blood increase the rate and depth of breathing #### Changes in carbon dioxide act directly on the medulla oblongata ### Chemical factors: oxygen levels #### Changes in oxygen concentration in the blood are detected by chemoreceptors in the aorta and common carotid artery #### Information is sent to the medulla Non-neural factors influencing respiratory rate and depth (continued) --------------------------------------------------------------------- ### Chemical factors (continued) #### Hyperventilation ##### Rising levels of CO~2~ in the blood (acidosis) result in faster, deeper breathing ##### Exhale more CO~2~ to elevate blood pH ##### May result in apnea and dizziness and lead to alkalosis ### {#section-5.ListParagraph} #### Hypoventilation ##### Results when blood becomes alkaline (alkalosis) ##### Extremely slow or shallow breathing ##### Allows CO~2~ to accumulate in the blood Respiratory Disorders ===================== Chronic obstructive pulmonary disease (COPD) -------------------------------------------- ### Exemplified by chronic bronchitis and emphysema ### Shared features of these diseases 1. ### Patients almost always have a history of smoking 2. ### Labored breathing (dyspnea) becomes progressively worse 3. ### Coughing and frequent pulmonary infections are common 4. ### Most COPD patients are hypoxic, retain carbon dioxide and have respiratory acidosis, and ultimately develop respiratory failure Chronic bronchitis ------------------ ### Mucosa of the lower respiratory passages becomes severely inflamed ### Excessive mucus production impairs ventilation and gas exchange ### Patients become cyanotic and are sometimes called "blue bloaters" as a result of chronic hypoxia and carbon dioxide retention Emphysema --------- ### Alveoli walls are destroyed; remaining alveoli enlarge ### Chronic inflammation promotes lung fibrosis and lungs lose elasticity ### Patients use a large amount of energy to exhale; some air remains in the lungs ### Sufferers are often called "pink puffers" because oxygen exchange is efficient ### Overinflation of the lungs leads to a permanently expanded barrel chest ### Cyanosis appears late in the disease Lung cancer ----------- ### Leading cause of cancer death for men and women ### Nearly 90 percent of cases result from smoking ### Aggressive cancer that matastasizes rapidly ### Three common types 1. #### Adenocarcinoma 2. #### Squamous cell carcinoma 3. #### Small cell carcinoma Developmental Aspects of the Respiratory System =============================================== Lungs do not fully inflate until 2 weeks after birth ---------------------------------------------------- ### This change from nonfunctional to functional respiration depends on surfactant ### Surfactant lowers surface tension so the alveoli do not collapse ### Surfactant is formed late in pregnancy, around 28 to 30 weeks Developmental Aspects of the Respiratory System (continued) =========================================================== Respiratory rate changes throughout life ---------------------------------------- ### Newborns: 40 to 80 respirations per minute ### Infants: 30 respirations per minute ### Age 5: 25 respirations per minute ### Adults: 12 to 18 respirations per minute ### Rate often increases again in old age Asthma ------ ### Chronically inflamed, hypersensitive bronchiole passages ### Respond to irritants with dyspnea, coughing, and wheezing Developmental Aspects of the Respiratory System =============================================== Aging effects ------------- ### Elasticity of lungs decreases ### Vital capacity decreases ### Blood oxygen levels decrease ### Stimulating effects of carbon dioxide decrease ### Elderly are often hypoxic and exhibit sleep apnea ### More risks of respiratory tract infection