Lungs and the Respiritory System

-Increase in PCO2 causes an increase in H2CO3 -Which leads to dissociation and an inHow do CO2 levels cause changes in pH crease in H+ ions and therefore ventilation? -Chemoreceptors in the brain sense the H+ ions and this leads to an increase in ventilation by increasing nerve impulses sent from the medulla What parts of the respiratory tract make up the 'upper' part? -Pharynx -Larynx -Nasal cavity What parts of the respiratory tract make up the 'lower' part? -Trachea -Bronchi -Lungs What is airway resistance? Resistance to airflow within the airways during inhalation and exhalation What is airway resistance proportional to? 1/radius^4 What are the two branches of the lungs? -Conducting zone -Transitional and respiratory zones What makes up the conducting zone of the lungs? -Trachea -Bronchi -Bronchioles -Terminal bronchioles What makes up the transitional and res- respiratory bronchioles, alveolar ducts, piratory zones? alveolar sacs What type of cells line the lungs? (Simple squamous) lung epithelium What are the three different types of lung epithelium? -Bronchi -Bronchioles -Alveoli Which of the three types of lung epithelium is the most simple? Alveoli -Not many cells thick Why is the alveoli epithelium so simple? -Non-ciliated -Thin to allow maximum gas exchange 1 / 11 Which types of lung epithelium contain goblet cells? -Bronchi -Bronchioles What is the role of goblet cells? Secrete mucus What is the role of mucus in the respira- Protects the lungs from foreign particles tory system? entering What is the role of cilia? Waft mucous and entrapped particles toward the oropharynx for swallowing or expectoration Which parts of the lung epithelium is ciliated? -Bronchi -Some parts of the bronchioles Which type of lung epithelium has 'club' cells? Bronchioles What is the role of club cells? -Secretion of surfactants -Detoxify inhaled substances (via the P450 enzyme) What are the two layers of mucous called? -Sol layer -Gel layer -Outside layer of mucous -Sticky substance which contains chemDescribe the gel layer of mucous and its icals, antibodies and other immune cells role in the respiratory tract to kill pathogens -Sticky nature helps to trap inhaled particulates What is an organ's parenchyma? -Its functional tissue -As opposed to its non-functional (structural) tissue known as its stroma What are the different types of parenchyma for the lungs? -Respiratory Bronchioles (RB) -Alveolar duct (AD) -Alveoli -Alveolar epithelial cells What are pneumocytes and what are the -Two different types are Type 1 and Type two different types? 2 2 / 11 What is the role and epithelium type of Type one alveolar epithelial cells (pneumocytes)? -Gas exchange (have a large surface area) -Squamous epithelium cells -Secretory (surfactants) What is the role and epithelium type of -Cuboidal epithelium cells Type two alveolar epithelial cells (pneu-They are also precursors for type one mocytes)? cells -SP-A -SP-B -SP-C -SP-D What are the four proteins that make up the surfactant produced by type two pneumocytes? Do surfactants increase or decrease sur-Reduces surface tension face tension in the lungs and what is the -Prevents alveolar collapse (atelectasis) benefit of this? How do pulmonary surfactants contribute to the immune system? -Control inflammation -Prevent microbial infections Which trimester does the lung epithelium grow in pregnancy? The final trimester What stimulates lung epithelium growth in premature babies? Coricosteroids (hydrocortisone) What is the different between adult human lungs and as a foetus? Foetus lungs are fluid-filled -Surge in corticosteroid and catecholamines during birth How are the lungs rapidly emptied in foe- -Activation of epithelial sodium channels tuses? (ENaC) (alters osmosis) -Pressure changes (squeezing through birth canal) What are the two ways in which the lungs receive blood? -Pulmonary circulation -Bronchial circulation -Pulmonary circulation is of a LOW O2 conc and a LOW pressure as it is from the RIGHT ventricle -Capillaries pass around the alveoli 3 / 11 -Bronchial circulation is of HIGH O2 and HIGH pressure as it is from the LEFT What are the main differences between (much stronger) ventricle the blood from the pulmonary circulation -Supplies the lungs with O2 and nutriand the blood from the bronchial circulaents tion? -NOT part of the systemic respiration process What part of the brain controls breathing? Medulla (oblongata) -Sense for PO2, PCO2 and pH What is the role of chemoreceptors in the -Can send messages to the medulla to management of breathing? increase breathing rates What type of muscles does the somatic nervous system control? Skeletal Which specific muscles do the somatic motor nerves control? Thorax muscles: -Diaphram -Intercostal What is the name of the somatic nerves that stimulates the diaphragm? Phrenic What is the role of autonomic nerves in the respiratory system? -Stimulate secretory cells and smooth muscles What main nerve do the others leading to the smooth muscle branch from (autonomic)? Vagus nerve What is a bronchospasm? Muscular contraction of the bronchioles Is the bronchospasm an autonomic or somatic response? Autonomatic Afferent sensory nerves (these go from What type of nerves signal to the brain the epithelium/smooth muscle to the information about the lung epithelium? brain) Does the parasympathetic nervous system constrict or dilate bronchioles? Constrict via muscarainic receptors Does the sympathetic nervous system constrict or dilate bronchioles? Dilate via adrenoreceptors 4 / 11 What are the different muscles involved in insipration? -External intercostal muscles -Diaphragm What are the different muscles involved in expiration? -Internal intercostals -Abdominal muscles -Hering-Breuer reflex What is the main role of: Slowly adapting -Which is the reflex that stops over-inflaStretch Receptors (SAR)? tion of the lung -Stimulated by sudden inflation What is the main role of: Rapidly adapt- -Also by irritant receptors in epithelium ing Stretch Receptors (RAR)? -Responsible for coughs and bronchoconstriction What are SAR and RAR examples of? Myelinated afferent sensory nerves What is an example of an unmyelinated afferent sensory fibre? Pulmonary and Bronchial C fibres What stimuli do Pulmonary and Bronchial C fibres respond to? -Noxious agents in the air (chemicals the can cause damage to the body) -Inflammatory agents generated by the body (histamine) What the Pulmonary and Bronchial C fibres cause when they are activated? -Reflex bronchoconstriction -Mucus secretion What is the pleural membrane? -Doubled membranes layer surrounding the lungs -It acts as a lubricant prevent friction against the inner wall of the thorax and lungs What is a pleural sac? The pleural membrane structure as a whole What is the name and role of the fluid inside the pleural sac? -Serous fluid -Lubricates each membrane sliding over eachother What are some ways in which airway resistance is increased in respiratory diseases? -Smooth muscle constriction -Obstruction with too much mucus -Lung collapse -Fibrosis 5 / 11 What is fibrosis? Formation of scar tissue GIve an example of a drug that is a Beta channel agonist bronchodilator Salbutamol Give an example of a drug that is a muscarinic antagonist bronchodilator Ipratropium -Type of steroids What are glucocorticoids with an exam- -Used to decrease inflammation in the ple? lungs -Prednisolone or budesonide What do vascular cells activate? -Angiotensin 1 -Which is biologically inert What converts the biologically inert angiotensin 1 to angiotensin 2? Angiotensin converting enzyme (ACE) What does angio -Vasoconstriction (increase BP) -Also causes water reabsorption to increase blood volume and again increase BP What enzyme inhibits bradykinin production? ACE What does bradykinin Vasodilation What is the PONS? The part of the brainstem that links the medulla oblongata and the thalamus (the bulge on the brain stem) What are the two different centres on the PONS? -Apneustic -Pneumotaxic What is the role of the apneustic centre of the PONS? -Prolongs medullary centre firing -Allows for a deeper breath What is the role of the pneumotaxic -Inhibits the apneustic centre -Causes expiration as apneustic centre no longer prolongs inhalation What is the pre-botzinger complex and? _Pacemaker for respiration -Located in the medulla CO2 can diffuse across the BBB (blood-brain barrier) much easier than 6 / 11 Why does PCO2 have a greater effect on ventilation than [H]+? H+ so will have a greater conc. in the CSF What is Ondine's curse? Loss of automatic control of breathing What does carotid mean? Relating to the arteries in the neck. What does aortic mean? Relating to the aorta What do the periphery (carotid/aortic) chemoreceptors mainly detect for? PCO2 What is a glomus cell? The chemoreceptor in the carotid and aortic bodies that sense for changes in pCO2 and pO2 -When O2 levels fall -The glomus cell has O2-sensitive K+ channels that close resulting in depolarHow does a glomus cell contribute to an ization -Dopamine is released which stimulates increase in ventilation rates? afferent fibres -These lead to the medulla and the medulla increases respiration What is Acetazolamide Carbonic anhydrase inhibitor How does acetazolamide stimulate respiration? -Creates a mild metabolic acidosis -Chemoreceptors respond to the increased [H]+ and increase ventilation How does doxapram increase -Closes K+ on glomus cells -Glomus cell forced to depolarise -Sends a message to medulla via afferent fibres to increase ventilation -Non specific CNS stimulation -Bronchodilator How does caffeine stimulate respiration? -Can be used in sleep apnoea and premature babies What is sleep apnoea? A temporary cessation of breathing during sleep -Alcohol -Narcotic analgesics 7 / 11 Name some examples of drugs that are respiratory depressants -Barbiturates -H1 antagonists What is myoglobin? A protein that holds a reserve supply of oxygen in muscle cells How many binding sites does myoglobin have? ONE Does pH and pCO2 affect myoglobins' affinity for O2? NO How is most of the CO2 in the body transported? -Bicaronate ions -HCO3-70% What are the 3 ways in which CO2 can be transported around the body? -HCO3- ions (bicarbonate) = 70% -Carbamino haeboglobin (HbCO2) = 23% -Dissolved CO2 = 7% Why does Ph decrease when O2 binds to Hb? O2 forces out the H+ ion Why does pCO2 increase when O2 binds to oxygen? -As O2 binds Hb's affinity for CO2 decreases -H+ ions also get released meaning there is a decrease in pH -Excess H+ ions bind to bicarbonate ions -Causing a shift in the equilibrium of carbonic acid production and more CO2 gets released What is the ventilation-perfusion ratio? ratio of alveolar ventilation to pulmonary blood flow -V/Q -V = ventilation (air that reaces the alveWhat is the equation for ventilation-peroli) fusion ratio? -Q = perfusion (blood that reaches the capillaries of the alveoli) What is V/Q mismatch? -When V/Q does not equal 1 -When the oxygen received to the lungs 8 / 11 is not relative to the amount of blood they are recieving What is hypoxaemia? Low blood O2 What is shunting? -Perfusion without ventilation -Unventilated alveloi -Usually caused by pulmonary odema What is hypercapnia? High blood CO2 What is hypoventilation? Slow and shallow breathing What is dead space in the lungs? -Ventilation but no perfusion -No gas exchange What is a pulmonary embolus (embolism)? Blood clot in the lung What is haematocrit? Ratio of RBC count to total blood volume What are the three physiological responses to low-inspired O2? -Increased ventilation -Pulmonary vasoconstriction (increases blood flow and therefore maintains a stronger diffusion gradient for gas exchange) -Increased haematocrit (EPO production by kidneys and subsequent bone marrow stimulation) What is chronic mountain sickness caused by? -Blood has a too-high haematocrit due to overproduction of EPO in the kidneys -Blood is very viscous What can be given to reduce chronic mountain sickness and why? -Acetazolamide (carbonic anhydrase inhibitor) -Inhibits EPO production in the kidney What are the two main ways to measure lung function? -Spirometry -Oximetry What is the tidal volume of the lungs? Amount of air entering or leaving the lungs during a breath (about 500ml) What is the residual volume of the lungs(RV)? Air left in the lungs when you exhale as much as possible 9 / 11 What is the inspiratory reserve Amount of air that can be forcefully inhaled after a normal tidal volume inhalation What are the three ways in which residual volume can be measured? -Helium dilution test -Body plethysmography -Nitrogen washout What are the two main types of lung diseases? -Obstructive -Restrictive Which type of lung disease do residual volume tests help to diagnose? Obstructive -Inflammation What are the features of obstructive lung -Decreased elastic recoil disease? -Both of these cause increased airway resistance -Restrict lung expansion What are the features of restrictive lung -Reduces the amount of air the lungs can disease? hold Is asthma res Obstructive What does spirometry test for? -How much and how easily air can move in and out of the lungs Give an example of a restrictive disease -Pulmonary fibrosis -Pneumothorax -Week respiratory muscles -Infant respiratory disease syndrome For spirometry what is FEV1 used to measure? Forced expiratory volume in 1 second Amount of air exhaled forcefully and What is the forced vital capacity (FVC)? quickly after inhaling as much as possible What parameter involving FEV1 and FVC can we use to compare lung health? FEV1/FVC ratio What does a wright/peak flow meter measure for? Peak Expiratory Flow Rate (PEFR) What does pulse oximetry measure? 10 / 11 Measures the O2 saturation of someone's blood/haemoglobin -Pulse oximetry measures % saturation Why does pulse oximetry not necessarily -Hb may be fully saturated even if numdetect anaemia? bers are low How does pulse oximetry work? Assesses red and infrared light transmission spectrum through tissue What is auscultation? Listening through a stethoscope What does a wheeze usually suggest about lung health? Asthma or COPD What do crackles usually suggest about -Infection lung health? -Small airways and alveoli 'popping' open 11 / 11