The Respiratory System Chapter16/ 23

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1 The Respiratory System Chapter16/ 23 There are two organ systems that cooperate to supply O 2 and eliminate CO 2 : the respiratory system and the cardiovascular system. The respiratory system provides for gas exchange, intake of O 2, and elimination of CO 2, whereas the cardiovascular system transports these gasses between the lungs and every body cell. Failure of either system has the same effect on the body: disruption of homeostasis and rapid death of cells from oxygen starvation and a toxic buildup of wastes. Contents: 1. Nose and Nasal cavity 2. Pharynx (throat) 3. Larynx (voice-box) 4. Trachea (windpipe) 5. Bronchial tube system 6. Lungs Accessory structures = 1. Diaphragm 2. Intercostal muscles Functions: 1. Pulmonary ventilation -movement of air in/out of lungs -breathing 2. Gas exchange with blood -blood gains O 2 and loses CO 2 -deoxygenated blood oxygenated blood 3. Sensory reception (smell) chemoreceptors 4. Sound production vocal cords 1

2 Laura Eberhardt 2 Monday, April 21, :45:15 AM ET 34:15:9e:2f:3a:92

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6 1. Nose and Nasal Cavity A. Nose Formed from L & R nasal bones and several cartilages Openings (nostrils) also called external nares Space inside nose (vestibule) Lined with: striatified squamous cells (continuous with skin) Nose hairs prevent entry of dust, dirt, etc B. Nasal cavity Space inside skull immediately posterior to nose Divided midsagitally by a septum Floor of cavity is called the hard palate Lined with: pseudostratified columnar epithelial tissue Many goblet cells (produce mucus) Posterior boundary with pharynx (internal nares) 2. Pharynx - common openings for the respiratory and digestive systems - also contains an opening leading to middle ear cavity - consists of three subdivisions: A. Nasopharynx Superior portion of pharynx Boundaries: internal nares tip of uvula Lined with: pseudostratified columnar (many goblet cells) Contains: pharyngeal tonsils, eustacian tube (passage to middle ear) 6

7 B. Oropharynx Middle portion of pharynx Boundaries: tip of uvula tip of epiglottis Lined with: stratified squamous cells Shared area with digestive system Contains: lingual and palatine tonsils. C. Laryngopharynx Inferior portion of pharynx Boundaries -tip of epiglottis glottis - top of esophagus (digestive system) Lined with stratified squamous Food/drink goes down wrong pipe here. Results in coughing. 3. Larynx A hollow box consisting of 9 pieces of cartilage. Thyroid cartilage Adams Apple Epiglottis protects airway when swallowing. All cartilages (except epiglottis) are hyaline cartilage. Epiglottis is elastic cartilage. Lined with pseudostratified columnar Contains: vocal cords. vocal cords = two pairs of ligaments stretched inside larynx. a) false vocal cords. More superior. Function: prevent air from leaking out when holding breath. b) True vocal cords. More inferior. Function: produce speech. Glottis = space between true vocal cords 7

8 4. Trachea A long hollow tube made of dense regular connective tissue Reinforced with C-shaped cartilage rings Hyaline cartilage Open end of C faces posteriorly. Located anterior to esophagus, in part goes through mediastinum Trachea is flexible/bendable Lined with: pseudostratified columnar. Contains many globlet cells. 5. Bronchial Tubes Inferior trachea splits into left and right primary bronchi. A. Bronchi: primary, secondary, tertiary Each primary bronchus travels through mediastanum on its way to the lungs. Once in lung, each splits into smaller band smaller tubes. primary secondary tertiary bronchi All have C-shaped hyaline cartilage rings Smooth muscle appears and wraps around all of them. B. Bronchioles Even smaller diameter branches off of tertiary bronchi. All branchioles lack C-shaped cartilage rings Only the larger bronchiole tubes are wrapped with smooth muscle, not smaller ones. Names of bronchiole tubes are (according to decreasing diameter) -terminal bronchioles -respiratory bronchioles -aveolar duct Bronchioles end at alveolus (functional unit of lungs) 8

9 6. Lungs - very advanced, gas exchange organs A. General information Large spongy organs that fill most of the thoracic cavity. Apex= top (superior) and Base bottom (inferior) Lung includes: 1. Portion of primary bronchus 2. All secondary and tertiary bronchi 3. All bronchioles Main part of lung are millions of tiny air sacs called alveoli Medial depression= hilum or hilus Left lung: Right lung: slightly smaller Slightly larger 2 major lobes 3 major lobes superior and inferior superior, inferior and middle 9

10 B. Pleura and pleural cavity Parietal pleura= lines the inner wall of thoracic cavity Visceral pleura = covers outer surface of lungs Space in between two membranes is the PLEURAL CAVITY Cavity is filled with a few drops of lubricating serous fluid C. Root of lungs - a collection of structures that enter/exit lungs at hilum: 1. pulmonary arteries/veins 2. primary bronchus 3. lymphatic vessels 4. nerves D. Alveolus * functional unit of lungs* =extremely tiny air sacks at the very end of bronchial tube network. -about 3 million per lung -total surface area ~140 square meters (40 times greater than the skin) Tissue: simple squamous Function: gas exchange between atmosphere and blood via simple diffusion. 10

11 E. Blood supply to lungs - 2 separate blood pathways pulmonary blood vessels Provides gas exchange for entire blood volume Heart pulmonary artieries lungs pulmonary veins heart bronchial blood vessels provides oxygenated blood to tissues/cells of the lungs. Normal part of circulation to a body organ. Quiz 1 7. Gas exchange and the respiratory membrane Gas exchange occurs between an alveolus and a capillary *both very thin walled *both simple squamous 11

12 A. Type II cells Cells in and outside of alveoli that secrete a liquid (surfactant) Functions: Prevent alveoli from clumping/sticking together Keeps respiratory membrane moist B. Alveolar macrophages WBC s located inside an alveolus. Function: Remove tiny dust particles by phagocytosis 8. Mechanics of Pulmonary Ventilation *Air flows in/out of lungs due to changes in pressure Air always flows: high pressure Low pressure Thus, in order to breath, 2 things must be true: a) to inhale Pressure of Atmosphere > Pressure of Alveoli b) to exhale Pressure of Alveoli > Pressure of Atmosphere A. Boyle s law The volume of a gas is inversely proportional to pressure. When one goes up, the other value goes down - INVERSE! 12

13 B. Three pressures involved in ventilation: alveolar_pressure_changes_during_inspiration_and_expiration.html atmospheric pressure: A constant value (760 mmhg) (assuming sea level for all numbers) Does not change when you breathe - YOU can not change the atmospheric pressure!!!!! alveolar (intrapulmonary) pressure pressure inside lungs/alveoli Varies: mmhg Can alternate above and below atmospheric pressure. intrapleural pressure Pressure inside of pleural cavity Varies: mmhg Always slightly below atmospheric pressure C. Inhalation 1. Diaphragm contracts, thus moves inferiorly. Rib muscles contract, thus pushing ribs outward 2. Volume of thoracic cavity increases 3. Pressure of thoracic cavity decreases, thus alveolar and intrapleural pressures decrease 4. Alveolar pressure will fall below atmospheric pressure 5. Air flows into lungs H low 13

14 D. Exhalation 1. diaphragm relaxes, thus moves superiorly. Rib muscles relax, thus allowing ribs to fall inward. 2. volume of thoracic cavity decreases. 3. pressure of thoracic cavity increases thus alveolar and intraplural pressures increase. 4. alveolar pressure will rise above atmospheric pressure. 5. air flows out of the lungs high low 9. Regulation of Breathing Rate A. Nervous regulation Diaphragm and intercostal muscles are controlled by area of the brain called: Respiratory Center (breathing center) 2 parts: 1. Medulla Oblongata a. Sets rhythmic pattern for breathing b. Sends action potential to muscles for contraction (2 seconds) c. Stops action potential to muscles for relaxation (3 seconds) 2. Pons a. Acts as a safeguard to protect breathing rate b. If lungs are too full of air inhibit medulla to cause exhalation c. If lungs are too empty of air stimulates medulla to cause inhalation We can consciously override this cycle at any time-for a short period of time. 14

15 B. Chemical regulation Chemoreceptors within the Blood vessels and brain monitor levels of O2 and CO2 in blood. They send afferent information to respiratory center for integration. Ex: If detect low O2 stimulate medulla to increase rate If detect high CO2 stimulate medulla to increase rate. 10. Diseases and Disorders of Respiratory System a) asthma An irritation of bronchi and bronchial tubes resulting in smooth muscle contraction = bronchoconstriction Triggered by: pollen, dust, exercise, smoke, certain foods Symptoms: difficulty breathing, coughing, wheezing Treatment: drugs to relax smooth muscles (bronchodialators) b) bronchitis An irritation of bronchi and bronchial tubes resulting in an overproduction of mucus by goblet cells. Leading cause: cigarette smoke Symptoms: constantly spitting-up mucus Treatment: drugs to inhibit goblet cells. c) cystic fibrosis An inherited genetic disease resulting in a buildup of thick mucuosy secretion in airway. Due to a faulty membrane protein and Cl- ion Stagnant mucus allows bacterial infections Treatment: drugs to breakdown mucus, antibiotics, mechanical percussion devices. 15

16 d) pulmonary embolism A blood clot that lodges in a pulmonary artery. Seriously reduces blood flow to lungs If clot is large enough death in minutes. Symptoms: chest pain, bloody coughing Treatment: anticoagulant drugs, (heparin) e) tuberculosis (consumption) A very contagious bacterial infection of lungs. Destroys healthy alveoli. Causes bleeding within lungs Body can heal itself, but replaced with non-functional scar tissue Drastic decrease in effeciencly of gas exchange. Treatment: antibiotics 16

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