Pulm Flashcards
Explain the anatomy of the lungs and their division into lobes and bronchopulmonary (BP) segments
Right lung:
Upper middle lower lobe, oblique and horizontal fissures
Left lung: upper and lower lobes, separated by oblique fissure; also has lingula
*fissure = double fold of pleura
BP segments: ~10 in each lung that represent further divisions of the lobes, each BP served by tertiary bronchus, pulmonary artery, and vein
What are the impressions on the medial surface of the lung and what are they created by?
Right lung: cardiac impression groove from azygos vein groove from SVC groove from esophagus
Left lung: cardiac impression and cardiac notch grooves from aortic arch groove from L subclavian artery groove from descending aorta impression from lower esophagus
Describe the development of the respiratory system. What clinical abnormalities can occur?
1) Ventral diverticulum develops off of the foregut early on in embryology
divides and forms trachea + 2 lung buds
lung buds evaginate into pleural cavities and become covered in the visceral pleura (visceral and parietal pleura meet at the roots of the lungs at the blood vessels)
2) Tracheoesophageal fistula
most common - esophagus ends in blind pouch, lower part of esophagus forms fistula with trachea
polyhydramnios (Excessive amniotic fluid) bc fetus cannot swallow
What are pleural reflections and recesses?
Reflection - parietal pleura turns back on itself
Recess - reflection is at an acute angle so lung doesnt enter this area during quiet breathing –> parietal pleura touching parietal (no visceral involved)
*2 intercostal spaces of recess (from 10th to 12th ribs) – acts as reserve space
Describe the articulation of the ribs and movement during inspiration
Ribs: 12 bones, articulate with vertebral column posteriorly and terminate as costal cartilage
head –> 2 vertebral bodies (corresponding + one above)
tubercle –> transverse process
Ribs 2-6: anterior posterior expansion
axis through head and tubercle; anterior ends of ribs move up, sternum moves anteriorly –> “pump handle” (caused by external intercostal muscles)
Ribs 7-10: transverse expansion
axis through head of rib and sternocostal joint
lateral shaft of rib elevates –> “bucket handle” (caused by contraction of the diaphragm and inferior displacement of the liver)
Using Boyle’s Law, describe the different stages of respiration and the muscles involved
*Boyle’s law: pressure and volume inversely related
1) At rest: intrapleural pressure ALWAYS negative (lung and chest wall pulling in opposite direction)
alveolar pressure = atmospheric pressure –> no gas exchange
2) Inspiration: Increase the volume in thoracic cavity –> Decreases pressure –> air rushes in bc of pressure differential
intrapleural pressure more negative, muscular contraction (External intercostals + diaphragm) > elastic recoil –> thoracic cavity enlarges
abdominal muscles and internal intercostals are relaxed
3) Expiration: decrease volume in thoracic cavity –> increased intrathoracic pressure –> air rushes out
intrapleural pressure less negative, elastic recoil increased and decreases alveolar volume, thereby increasing alveolar pressure, abdominal muscles and internal intercostals contract if need be
alveolar pressure > atmospheric pressure –> air flows out of alveoli
Explain how cardiac function is linked to pulmonary function
Deep breath –> lowers intrathoracic pressure –> dilates great veins –> increases venous return to the heart
Expiration (also laughing, coughing) –> increased intrathoracic pressure –> impedes venous return (thats why face flushes, veins become more prominent)
What is the function and innervation of the diaphragm? What is paradoxical movement?
Function: anything requiring change in intrathoracic or intraabdominal pressure
eg breathing, phonation, laughing, singing, coughing, sneezing, urination, defecation
*works with pelvic diaphragm to change intraabdominal pressure
Innervation: phrenic nerve (bilaterally)
unilateral loss of the phrenic nerve - diaphragm doesnt descend during inspiration, is instead forced superiorly
What is the nerve supply to the lungs?
More specifically, what is the innervation of bronchial smooth muscle?
1) Afferent - on vagus nerve, feedback on pain, pressure, stretch in the pulmonary veins
Sympathetic - postganglionic thoracic splanchnics, innervate smooth muscle and blood vessels
Parasympathetic - preganglionic, synapse on small ganglia on bronchial tree; innervate smooth muscle
2) Vagus - parasympathetic constriction
epinephrine (from adrenal medulla)- sympathetic beta2 adrenergic dilation
What happens during open (sucking) pneumothorax? What happens during tension (positive pressure) pneumothorax?
1) Open (sucking) pneumothorax
open chest wound –> air enters pleural cavity –> negative intrapleural pressure lost –> collapse of lung –> reduced venous return to the heart
Inspiration: mediastinum shifts –> compresses opposite lung
Expiration: mediastinum and unaffected lung shift back to normal position, but venous return further affected by distortion of vena cavae
2) Tension (positive pressure) pneumothorax
valve-like chest wound –> air enters pleural cavity –> negative intrapleural pressure lost –> lung collapses –> reduced venous return to the heart
Inspiration: mediastinum shifts –> compresses opposite lung
Expiration: valve opening closes –> air cannot escape –> increases intrathoracic pressure –> unaffected lung is still compressed
and venous return further affected by both increased pressure and distortion of vena cavae
*pneumothorax lowers Pa02 bc it creates a shunt V/Q defect
What is hemothorax?
Hemothorax- blood in the thoracic cavity, blood may not clot, since liquid is not compressible it makes the lungs smaller and smaller
blood can come from lung, thoracic wall arteries, heart, abdominal structures, or intercostal vessels
What is the structure and function of mucosa?
Wet epithelium + lamina propria (adjacent epithelial tissue)
Epithelium - pseudostratified columnar, has cilia and goblet cells produce saliva, can also have intraepithelial lymphocytes which migrated from lamina propria
basement membrane
Lamina propria - loose connective tissue with blood vessels, nerves, and lots of lymphatic vessels (called MALT- defense mechanism)
Define the conductive vs respiratory parts of the respiratory system
Conducting: nose and nasal cavity –> nasopharynx –> pharynx –> larynx –> trachea –> primary, secondary, tertiary bronchii –> bronchioles (end is terminal bronchioles)
function: warm, moisten, clean inspired air
Respirating: respiratory bronchioles –> alveolar ducts –> alveolar sacs –> lined with alveoli (have alveolar pores in the walls)
function: gas exchange
What are the cells in olfactory mucosa?
How do you differentiate from respiratory epithelium?
Olfactory mucosa - on roof of nasal cavity
1) olfactory receptor cells - responsible for sense of smell, secretion (by Bowman’s glands in the lamina propria) that dissolves odor molecules – impulse carried by olfactory nerves
2) sustentacular cells - support and nourish olfactory receptor cells
3) basal cells - stem cells that replace both receptor and sustentacular cells
3 layers of cells, much thicker, and no goblet cells
Describe the protective mechanisms of the respiratory tract
sneeze reflex sensory: V1 and V2 (ophthalmic and maxillary, trigeminal)
cough: vagus nerve
What are the 3 layers of trachea and bronchii?
1) Mucosa - epithelium + basement membrane + lamina propria with BALT (lymphatic tissue- defense mechanism)
2) Submucosa with serous (pink) and mucous (frothy white) glands and lymphoid tissue
3) Adventitia of connective tissue - hyaline cartilage (keeps airway open) and smooth muscle (regulates diameter of airways)
What are the cells in the respiratory epithelium?
1) Goblet cells - produce mucous which traps foreign particles
2) ciliated cells - move mucous with trapped foreign material –> mucociliary escalator (mucous swallowed or spit out once it reaches pharynx)
3) Basal cells - stem cells replace goblet and ciliated cells, can also sense environment
4) DNES/K cells - secrete vasoactive substances into lamina propria
* bowman’s glands in CT below epithelium (ie lamina propria) - secretion for dissolving odor
What is the difference between a pulmonary lobule and acinus?
Lobule - tissue served by terminal bronchiole
Acinus - tissue served by respiratory bronchiole
What comprises the blood air barrier?
Type I pneumocyte of alveoli - squamous cell where gas exchange occurs
Continuous capillary endothelium
shared basement membrane between the two epithelia
interstitial tissue away from blood-air interface, dont want any fluid leakage
What is the function of Type II pneumocytes?
dome shaped cells in alveolar wall, contain lamellar bodies that discharge surfactant into alveolar lumen - reduces surface tension and prevents alveolar collapse during expiration, contributes to elastic recoil of lung, also has defense functions
can maybe also proliferate to replace Type I (where gas exchange occurs) and Type II
What is the function of alveolar dust cells?
Macrophages that travel through alveolar pores to phagocytose foreign matter that escaped the mucous blanket
enter lymphatics and go through multiple lymph nodes to drain the hilar lymph nodes –> see black lymph nodes at hilum of the lung
also secrete antitrypsin inhibitor (when you want elastase and want to break down elastic fiber)
What is the pathology of emphysema?
Destruction of tissue distal to terminal bronchioles - elastic fibers in interstitial tissue are destroyed –> air passages cannot remain open –> gas exchange compromised and surface/diffusion area decreases
normally elastase (which makes new elastic breaks down elastic fiber), inhibited by antitrypsin in emphysema, toxins suppress antitrypsin --> elastase produced in excess --> elastic fibers destroyed --> airways cant stay open
What are the major physiologic and nonphysiologic contributors to body acid load?
1) Metabolism of fats and carbohydrates –> H2C03 (carbonic acid)
* C02 is volatile acid, expired via respiration
Metabolism of protein –> H2PO4- (phosphoric and sulfuric acids)
*non-volatile acids, have net negative charge
buffered by renal HC03- retention, H+ secretion
2) Pathophysiologic
ketoacids (starvation, DMII)
salicylic acid (Aspirin)
lactic acid
What happens during respiratory acidosis?
What is compensation rule #1 for acute respiratory acidosis?
Compensation rule #2 for chronic respiratory acidosis?
Decreased pH, increased PC02 in blood
Rule #1: Up 1 for 10
[HC03-] increases 1 meq/l per 10 mm Hg rise in PC02 above 40
Rule #2: Up 4 for 10
[HC03-] increases 4 meq/l per 10 mm Hg rise in PC02 above 40
What happens during respiratory alkalosis?
What is compensation rule #3 for acute respiratory alkalosis?
Compensation rule #4 for chronic respiratory alkalosis?
Increased pH, decreased PC02 in blood
Rule #3: Down 2 for 10
[HC03-] decreases 2 meq/l per 10 mm Hg decrease in PC02 below 40
Rule #4: Down 5 for 10
[HC03-] decreases 5 meq/l per 10 mm Hg decrease in PC02 below 40
Why is there limited capability of compensation in metabolic acidosis?
initially Kussmaul breathing lowers PC02 bc of increased tidal volume –> increases pH
but lowering PC02 –> lowers renal HC03- reabsorption –> decreases plasma [HC03-] –> decreases pH again
Why is there limited capability of compensation in metabolic alkalosis?
initially reduced ventilation raises PC02 –> Decreases pH
but raising PC02 –> increases renal H+ secretion –> increases HCO3- reabsorption and generation –> increases plasma [HC03-] –> increases pH again
What is negative pressure breathing?
What is positive pressure ventilation?
1) Negative pressure breathing: alveolar pressure alveolar pressure (mechanical ventilator)
How is the gradient for negative pressure breathing generated?
Muscles of inspiration contract –> intrapleural pressure becomes more negative –> transmural pressure difference increases (inside alveolar pressure - outside intrapleural pressure) –> alveoli all passively expand (bc of structural interdependence, alveoli are tethered together) –> alveolar volume increases –> alveolar pressure decreases –> air rushes in
*alveolar pressure needs to be less than atmospheric pressure for this to occur
