Glossary of mechanisms pulmonary
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- How many primary bronchii does trachea branch into?
- 2 primary that branch into several smaller ones
- at which branches to bronchii become bronchioles
- 12th-16th branches
- where do the terminal bronchioles occur
- 17th-24th branches
- What is found at the end of the terminal bronchioles?
- alveolar ducts, sacs, and alveoli
- What happens when bronchioles 12-16 over secret mucous or constrict?
- asthma or chronic bronchitis
- Where is the "dead space"?
- down to the 16th branch
- Dead space=
- 150 mL of air per breath that's not being exchanged; remains in the passageways
- where does diffusion of O2 take place?
- from terminal bronchii to the alveoli
- approx how many alveoli?
- 300 million
- what's the total surface area?
- 50-90 sq. meters
- everything distal to the terminal bronchioles
- What happens to the acinus in emphysema?
- they lose their alveolar sacs and gas diffusion area decreases
- How do the bronchii contract to increase airway resistance?
- via smooth muscle cells that wrap around the bronchs. and contract to narrow the airway
- How do the alveoli receive blood?
- pulmonary arterioles divide into small capillaries that run in sheets btw./among alveoli
- Which muscles are used for inspiration?
-accessory inspiratory muscles (scalenes and sternocleidomastoid)
- Which are oriented like levers btw. the ribs and cause elevation of the ribcage?
- external intercostals
- which of these is innervated by the phrenic nerve (from C4)?
- Which are used during very labored breathing and also turn the head?
- accessory inspiratory muscles (scalenes and sternocleidomastoid)
- Which pulls on the sternum and middle third of the clavicle?
- Which hooks onto ribs 1 & 2
- Where does sternocleidomastoid originate?
- mastoid of skull
- What is the scalenes innervated by?
- cervical plexus (c1-c4)
- Which muscle separates thoracic from the abdominal cavity?
- Where does scalenes originate?
- from the transverse process of cervical region
- where is the chest tube inserted in a thoracostomy?
- superiorly on the rib (can cut nerve or vein if underneath)
- what's a pneumothorax?
- fluid in the pleural space
- What are the expiratory muscles?
- what do the abdominal muscles do?
- pull lower ribs down
- What is the action of the diaphram in expiration
- What do the internal intercostals do?
- pull down ribs and compress the thorax
- What does a spirometer measure?
- static lung volumes- how much air is blown
- What are the static lung volumes?
- Resting Tidal Volume (TV)=
- -the amount of air inhaled/exhaled when breathing normally
- Inspiratory Reserve Volume (IRV)=
- -the amount of air that can be taken in, in addition to a normal breath
- Expiratory Reserve Volume (ERV)=
- -amt of air that can be expelled after inhaling all the way
- Residual Volume (RV)=
- -amt of air left in the lungs after expelling as much air as possible
- Functional Residual Capacity (FRC)=
- =ERV + RV
- Vital Capacity =
- -the max amt. of air that can be moved
- What do the static lung volumes tell about lungs and chest wall?
- reflect their elastic properties
- Why do pt's have difficulty getting air out in obstructive diseases?
- due to lost collagen and elastin, narrowed passages, and excess mucous secretions
- What happens to the small and terminal bronchioles?
- they collapse
- What static lung volume is an indicator?
- a dec'd FVC (longer than 6 secs)
- Is slow VC okay in obstructive?
- what are examples of obstructive diseases?
- emphysema, asthma, chronic bronchitis
- Why do pt's have diff breathing in restrictive lung diseases
- due to lost elasticity
- what happens to the lungs
- they become fibrosed- like a tough non-compliant football
- What happens to the VC?
- it's smaller
- where is the visceral pleura located
- on the lung
- where is parietal pleura located
- on the inside of the chest cavity
- what lies between these two layers
- what is this space called
- interpleural space
- what does the space allow for
- causes the lungs to stick to the inside of the chest wall- creates a strong bond
- is it positive or negative pressure
- negative pressure b/c the chest wall wants to go out and the lungs want to recoil back inward
(a fluid vacuum)
- What causes lung recoil
- surface tension
- At FRC, how expanded is the chest
- Surface tension=
- a collection of molecular forces that occurs whereever gas/fluid interface exists
- what causes it
- the thin fluid layer between the alveolar cells and the air
- fluid which decreases surface tension to keep lungs from collapsing
- chemical name for surfactant
- what produces it
- type 2 epithelial cells within the alveoli
- Law of LaPlace=
- P= 2(T/r) pressure= 2*(tension/radius)
- how does this apply to pressure in the lungs?
- -pressure in a fluid bubble is a fx of the surface tension of the fluid and the radius of the bubble
-if 2 bubbles (alveoli) have diff diameter but are lined by fluids w/ the same surface tension, the pressure (resistance) inside the smaller bubble will be greater, so smaller alveoli are more diff to fill with air than lg. ones
- How does surfactant solve this problem?
- -its more concentrated in smaller alveoli, making their surface tension less than the larger ones
-this lower tension helps equalize pressure so smaller ones can inflate
-they receive a proportionate amt of air as large ones
- Lung compliance=
- change in volume/change in pressure
- what shape is the compliance curve
- what's on the x-axis
- intrapleural pressure (Pip)
- whats on the y axis
- lung volume
- Where does a change in Pip produce the biggest change in volume
- middle (less at beginning and end)
- what is the "equilibrium" pt. btw recoil and chest wall expansion?
- where does most of normal insipirated air go to in the lungs
- the base
- where does most output of the right ventricle go
- the alveolar capillaries in base of lung
- When can mismatches in the ventilation/perfusion (V/Q) ratio occur?
- -mucus plug blocks ventilation
-pulmonary embolism blocks blood flow
- What does the pulmonary funtion test, FEV1 test
- forced expiratory volume at one second
- whats normal FEV1 value?
- 75% of FVC
- How much CO goes to pulmonary (alveolar)vasculature for oxygenation
- where does the rest go?
- bronchiole vasculature and doesnt get oxygenated
- what happens to it?
- from the thoracic aorta there is a separtate ciculation that oxygenates the lung parenchyma and gets pumped back into pulmonary veins and mixes w/ oxygenated blood to by pumped from LV
- why is Hgb never 100% saturated
- b/c some supplied the lungs and was deoxygenated
- Mean Arterial Pressure=
- Pd +(Ps-Pd)/3; normal is 93mmHg; P in RA is 0
- What is LV CO?
- 5L/min; RV=LV CO normally
- Is pulmonary vascular resistance higher or lower compared to rest of body
- lower- if it goes up, blood backs up and RV can fail
- What division of the nervous system controls how much blood goes to the lung
- ANS, including parasympathetic and sympathetic
- area of lung that's not well ventilated (= degree of ventilation)
- what does the degree of hypoxia determine
- -status of the pulmonary arterioles (dilated or constricted)
-i.e. a decr in ventilation causes arterioles to constrict and that area shuts down
-vasoconstriction is directly proportional to hypoxia
- does skeletal muscle work like this
- no-its the opposite- less flow means dilation
- what does pulmonary vasoconstriction help to maintain
- V/Q ratio
- what happens with chronic hypoxia
- -local arterioles continuosly vasoconstricted
-total pulmonary vascular resistance inc's
- who does sleep apnea most affect
- overweight males
- whats the most important control of pulmonary vascular resistance
- besides hypoxia what else causes inc's pulmonary vascular resistance
- -pulmonary embolism
- what are causes of fibrosis
- -systemic sclerosis
-coal miners lung
- how does LV failure cause RV failure
- it cant pump out what the RV feeds in so its pumping against more resistance
- Which receptors are the controllers of air flow
- muscarinic and beta
- where are muscarinic located
- smaller bronchi and bronchioles
- sympathetic or parasympathetic?
- adrenergic sympathetic fibers
- fibers send APs to receptor that releases NE to dilate (not all receptors are innervated)
- when does it occur
- when we're in a vegetative state
- where are betas located
- on bronchioles, arterioles, heart muscle, and the GI tract
- what do asthma meds like proventil do?
- -acts as a B2 agonist- binds and dilates
-can also bind B1 receptors in heart to inc heart rate
- Where are respiratory rhythm generators (RRGs) located
- in the medulla
- what are the 2 types
- -dorsal respiratory grp
-ventral respiratory grp
- which controls inspiratory phase
- what does ventral control
- expiration and inspiration
- how are primary RRGs modified
- from the pons
- what are the abnormal respiratory rhythms?
- 1. Bradypnea (slow)
3. Cheyne-Strokes (waxy and wany ventilatory depth w/ periods of apnea)
4. Hyperventilation (rate of vent exceeds tissue demand resulting in hypocapnia)
5. Hypoventilation (rate of vent is less than tissue demand resulting in hypercapnia)
6. Hyperpnea (inc'd ventilation due to inc'd O2 demand from tissues)
- What controls rate and depth of NL respiration?
- 1. Stretch receptors
2. Irritant receptors
3. J (Juxta capillary) receptors
4. Cerebral Cortex
5. Limbic System
- Which allows voluntary control over breating/respiration?
- Cerebral cortex
- Which increases rate and depth?
- Which are found in smooth muscle of bronchioles?
- stretch receptors
- what do they do
- creat autonomic endpoint to inhalation
- Which are found in lung parenchyma btw. alveoli?
- J receptors
- what do they do?
- detect interstitial distortions from pulmonary distortions (i.e. edema/fibrosis cause rapid and shallow breathing)
- which are found in epithelial layers of airways?
- what do they detect?
- anything noisesome thats inhaled (stops breathing- then causes rapid shallow breathing)
- Which controls breathing based on emotion?
- limbic - our "emotional brain"
- what are the three "f's" that are controlled by the limbic?
- feeding, fighting, fornication
- What are the controllers of long term respiration?
- Chemoreceptors- Peripheral and Central
- What are the 3 peripheral chemoreceptors?
- 1. Carotid Sinus
2. Carotid Bodies
3. Aortic Bodies
- Which has the highest rate of blood flow in the whole body?
- Carotid sinus
- Where are carotid bodies found?
- on medial side of carotid sinus
- what are they innervated by?
- by carotid sinus nerve which joins glossopharyngeal nerve to enter brainsteam
- Where are aortic bodies located?
- aortic arch
- What innervates aortic bodies?
- afferent vagus fibers
- What do both aortic and carotid bodies do?
- -monitor plamsa for O2 content (hypoxia monitoring)
-report to RRGs in medulla
- which are more important
- what do they do if stimulated by hypoxia?
- cause an increase in the ventilation and/or depth of respiration
- Where are central chemoreceptors located?
- on the ventrolateral portion of the medulla
- whats the only thing they respond to?
- changes in the plasma pCO2 b/c the blood brain barrier in medulla prevents entrance of any molecules with charge (CO2 is neutral and small)
- Which receptors are responsible for 80% of regulation of plasma pCO2
- central chemos (other 20% is carotid bodies)
- Which respond faster to plasma pCO2 changes
- carotid chemos
- Which are used for long term?
- central chemos
- Whats the pH2O at 37 degrees C?
- Whats the pO2 of inhaled air
- 713 mmHg
- Whats the pO2 in lower bronchiole tree
- 150 mmHg (100 mmHg in alveoli)
- pO2 of arterial blood=
- pCO2 of arterial blood=
- pO2 of venous blood=
- pCO2 of venous blood=
- 2 ways of carriage of O2:
- 1. physical solution-O2 is dissolved in plasma
2. bound to Hgb
- How much O2 does plasma carry?
- 0.3mL O2/dL plasma
- How much O2 does Hgb carry?
- 15mL O2/dL blood
- 3 ways of carriage of CO2:
- 1. physical solution (in plasma)
2. form of carbamino compounds
3. carried as bicarbonates
- How much CO2 does plasma carry?
- 2.76mL CO2/dL plasma
- How does CO2 form carbamino compounds?
- combines with N2 group of amino acid, occurs in plasma proteins and in Hb
- What's the most common way CO2 is carried?
- as bicarbonate- 70% exhaled CO2 has been carried as bicarbonate
- Is more CO2 or O2 carried in physical solution (plasma)?
- Bohr Effect=
- inc. in blood pCO2 in the tissues causes a dec in Hb affinity for O2
-allows O2 to be released to tissues
- Haldane Effect=
- inc in blood pO2 in lungs causes a dec in Hb affinity for CO2
-allows CO2 to let go
- at what pressure is Hb 50% saturated
- what is p50?
- plasma O2 at which Hb is 50% saturated
- what causes the oxy-Hb dissociation curve to shift to the right?
- -dec in pH
-inc. in pCO2
-inc. in temp
-inc. 2.3DPG (Hb releases O2 more)
- what does a shift to the right mean?
- -p50 is increased
-dec'd affinity of Hb for O2
-shifts b/c to keep Hb 50% saturated, it must encounter higher pO2
-present during exercise
- what causes the oxy-Hb dissociation curve to shift left?
- -inc'd pH
- what does a shift to the left mean?
- -p50 is decreased
-inc'd affinity for Hb for O2
-shifts b/c to keep Hb 50% saturated, it must encounter lower pO2
-present in vegetative state
- What does the diffusing capacity of the lungs measure (DLco)
- ability of lung tissue to allow diffusion at the right level
- Which problems are due to bronchi and bronchiole constriction?
- 1. asthma
2. acute/chronic bronchitis
4. bronchogenic cancer
- what problems are due to histological areas of the lung (alveoli)?
- 1. atelectasis
3. air space diseases (pnemonia and emphysema)
- What are diseases of the plurea?
- 1. pleural effusion
- what diseases result from problems with the vessels?
- 1. pulmonary embolism
2. primary pulmonary HTN
- What are the problems with interstitium btw. alveoli?
- 1. infection (pneumonia)
2. Fibrosis (restrictive, idiopathic, environment, autoimmune)
- At what rate is peural fluid normally formed on the parietal pleural surface?
- about 0.1 ml/kg/hr
- The aqueous phase of this fluid is reabsorbed by the___________
- the visceral pleural capillaries
- The protein phase is reabsorbed by ____________
- the parietal pleural lymphatics
- Balance between fluid formation and reabsorption normally leaves how much in the pleural space
- 5 -15 ml (not dectable on cxr)
- what is a pleural effusion
- an abnormal accumulation of fluid and is often detectable on plain chest film
- 5 major types of pleural effusion:
- 1. exudate
- An exudate has at least one of these features:
- - more than ½ the protein content of the same patient’s serum
- more than 6/10 the lactate dehydrogenase (LDH) content of the same patient’s serum
- an LDH content greater than 2/3 the upper limit of “normal serum”
- are exudates active or passive
- they're active abnormal cellular process
- causes of exudates:
- 1. Infections: TB, fungus/parasite, pneumonia (bacterial or viral)
5. drug reaction
- which are the 2 most common causes of exudates
- cancer and pneumonia
- What is a transudate?
- the passive movement of fluid resulting from:
1. increased vascular hydrotstatic pressure
2. decreased plasma oncotic pressure
3. increased negative intrapleural pressure
- What are the 4 causes of transudate?
- 1. CHF
2. Nephrotic Syndrome
3. Constrictive Pericarditis
4. Acute Atelectasis
- which of these is the most common cause of pleural effusion overall
- how does CHF cause pleural effusion?
- LV failure causes pressure to increase in the pulmonary vessels ----->
increased hydrostatic pressure
- which causes decreased plasma oncotic pressure?
- nephrotic syndrome
- what happens with constrictive pericarditis?
- noncompliant pericardium restricts ventricular filling and mimics CHF
- how does acute atelectasis cause transudate?
- increases negative intrapleural pressure
- how does a PE cause transudate?
- it leads to inc’d Pul.Vasc. Resistance thus inc’d hydro-static pressure which leads to transudate
- what is an empyema?
- a form of exudate where fluid is turbid or purulent due to infection in the pleural space itself
- Whats a hemothorax?
- gross blood in pleural space sually due to chest trauma
- Whats a chylothorax?
- milky in appearance due to presence of cholesterol complexes
- when is chylothorax most common?
- in tuberculous pleuritis or rheumatoid
- sn/sx of small Pleural effusion (less than 200mL):
- assymptomatic (no physical findings)
- sn/sx of large Pleural effusion (more than 200mL):
- dullness to percussion
- massive effusion on one side may push the trachea (and therefore the tracheal
air column ) to the opposite side.
- what does pleuritic chest pain indicate?
- exudative pleural effusion
- what does pleural friction rub indicate?
- X-ray findings for pleural effusion:
- -blunting of the costophrenic sulcus
-“Thickening” of interlobal and/or interlobular lung fissures on plain film
-Crescentic line or meniscus
- What causes thickening
- due to fluid which has invaded the space by capillary action and shows up
on Xray as a white line
- What is loculated fluid
- fluid trapped by pleural adhesions in one area along the chest wall
- what does this look like on film?
- a white shadow with its broad base toward the chest wall and a point toward the lung
- What causes the crescentic line or meniscus?
- if effusion doesn't go to apex, upper edge of opacification is curved
- When is a thoracentesis performed?
- when etiology of effusion is in doubt, esp if exudate is suspected
- aspiration of some of the fluid with a syringe and needle by inserting it through an intercostal space which the Xray shows to be somewhere below the upper level of the effusion
- must also be placed immediately above the rib in order to avoid hitting intercostal nerves and vessels which lie immediately below any rib
- Tx for exudative:
- Tube thoracostomy- chest tube
- where is the chest tube placed
- low in the chest in order to get most of the fluid above it, typically in the 5th or 6th interspace at the midaxillary line or more posterior
- what is a chief goal of drainage?
- prevent the progression from exudative to fibropurulent and more “organized” stages in which a “peel” may be formed which can trap a portion of the lung and cause permanent loss of lung function
- Tx for transudative:
- -first try tx for underlying condition
-if the effusion is large enough to compress the lung and affect breathing or cause tracheal/mediastinal shift, then a chest tube is placed for drainage
- Tx for hemothorax:
- -chest tubes
-thoracotomy for large volumes or clots
- Thoracotomy =
- surgical procedure which leaves the patient with a pneumothorax, for which a thoracostomy tube must then be placed
- what is a pulmonary embolus?
- anything which moves from somewhere in the systemic venous circulation to the right heart and becomes ejected by the right ventricle into the pulmonary circulation
- what is the most common cause of pulmonary embolism?
- a thrombus that forms in the deep veins of the leg (a DVT), dislodges to become an embolus and goes to the lungs (also called a a pulmonary thromboembolus)
- Other causes of pulm. embs?
- 1. Air embolus: during neurosurgery, or from central venous catheter
2. Amniotic fluid embolus: during active labor
3. Fat embolus: from long bone or hip fractures
4. Foreign body embolus: a piece of an I.V. catheter
5. Tumor cell embolus: renal cell carcinoma
- Essentials of Dx:
- -abrupt onset of dyspnea, tachypnea, chest pain, hemoptysis and/or syncope
-high risk for venous thrombosis (DVT)
-Unmatched or mismatched defects on V/Q scan
-Diagnostic findings on pulmonary angiogram or spiral CT
- what inc's risk of a DVT?
- 1. Non-ambulation: the bedridden patient or long distance traveler
2. Recent surgery: ie total hip replacement
3. Woman on oral contraceptives who smokes
5. Cancer,esp adenocarcinoma of breast, pancreas, prostate, ovary
6. Hereditary Hypercoagulability
7. prolonged dehydration
- what are the risk factors for pulm emb?
- same as DVT
- Most common veins for emboli to arise from:
- Deep veins of the calf:
-Anterior & posterior tibial veins
- Peroneal vein
- Do they form in superficial veins (i.e. small or great saphenous)?
- Where can a thrombus propagate or dislodge to from the deep veins of the calf?
- Popliteal vein and Ileofemoral vein to form a proximal DVT
- What are the sn/sx of a DVT?
- -FEW OR NO SX
- dull ache or tightness in leg, esp. while walking
- distention of superficial collateral veins, slight edema maybe
-Homan's sn = leg pain on passive dorsiflexion at ankle
- Why is dx difficult?
- -Dx only by history and physical
-Sns & sx of PE are not specific for PE
-sn/sx aren't conclusive
- Sn/sx of PE:
- -dyspnea and pain on inspiration
-Cough, wheezing, crackles, hemoptysis, leg pain all possible
-Pleural friction rub, cyanosis possible
-Accentuated pulmonary component of second heart sound ( S2
- Lab findings:
- 1. CXR (to rule out pneumonia, pneumothorax, massive pleural effusion, TB, or preexisting CHF)
2. ABG's: show hypoxemia, and usually respiratory alkalosis due to hyperventilation
3. ECG: may show sinus tachycardia and non-specific ST segment and T wave changes
- On ECG, a Tall R wave in V1 indicates:
- acute right heart strain from sudden increase in pulmonary vascular resistance
- ECG will help rule out:
- Why does a PE cause RV failure?
- A clot blocks a major flow artery so there are fewer flow channels for the blood. This inc's pulmonary vascular resistance and RV can't adjust to work harder.
- Which test is used to determine the presence of a thrombus ANYWHERE:
- Plasma D-dimer level: Lack of increased D-dimer is strong evidence for no thrombus
- What is used to detect a DVT?
- 1. Contrast Venography (will show intraluminal filling defect in vein- not as common as other 2)
2. Duplex ultrasound with color flow doppler
3. GADOLINIUM-ENHANCED magnetic resonance venography
- To detect a PE?
- 1. Spiral CT
2. Pulmonary angiography (done after a V/Q)
3. V/Q Scan
- In a V/Q scan which is done first?
- Q- perfusion tested via radiocontrast injection.
NL shows 2 whole lung silhouettes
- What will the Q scan show if there's a thrombus?
- A perfusion defect:
a hole in the picture, where blood is not flowing
- Usually, no perfusion defect=
- No PE
- If a perfusion defect is found, then what?
- do a V scan
- V-scan =
- patient inhales radioactive gas and a camera takes a ventilation picture. If there is no parenchymal pathology in the lungs, they show up again as two whole lung silhouettes
- Does a PE causing matching V and Q defects (i.e. same part of lung shows up defective)?
- no- mismatching defect
- b/c a thrombus of a PE is in pulmonary artery /arteriole, not in the bronchi / bronchioles
- What other pathology shows V/Q defects?
- emphysema shows matching defects
- If you find 2 or more unmatched Q defects:
- PE V. LIKELY
- If you find mismatched Q and V defects:
- PE LIKELY
- If you find matched Q and V defects:
- PE UNLIKELY (suspect emphysema)
- If V/Q is equivocal but PE suspicion is high, order a:
- pulmonary arteriogram
- Prevention (the best Tx):
- -avoid risk factors for DVT
-after surgery, early ambulation, intermittent pneumatic compression stockings, and low dose heparin or Low Molecular Weight Heparin ( LMWH)
- What are exs. of low molecular wt. heparin drugs?
- -Lovenox ( enoxaparin)
- Tx of confirmed PE:
- -Immediate anticoagulation with unfractionated Heparin
-or LMWH may be used
-Longterm 3 - 6mos anticoagulation with Coumadin (warfarin)
- What are the 4 main categories of a pneumothorax?
- 1. primary spontaneous
2. secondary spontaneous
- Which occurs as a complication of lung disease?
- Which occurs in the absence of underlying lung disease?
- Which is due to blunt or penatrating trauma or iatrogenic causes?
- What are iatrogenic causes?
- -subclavian or internal jugular vein catheterization
- percutaneous lung biopsy
- pleural biopsy
- pulmonary barotrauma from mechanical overventilation
- What happens in a tension PTX?
- air enters thorax during inspiration but does not exit on expiration
- positive interpleural pressure > ambient pressure
- trauma, CPR or mechanical ventilation
- What are sn of any PTX?
- -Acute onset ipsilateral chest pain (minimal to severe)
- What are the objective findings?
- Mild cases-minimal -if PTX < 15% of hemithorax…perhaps only mild tachycardia
Severe cases- unilateral chest expansion, tracheal & mediastinal shift toward side
opposite PTX, breath sounds & fremitus decreased or absent, percussion hyperresonance or tympany, CXR shows “visceral-pleural line” and/or area of thorax with markedly absent pulmonary vasculature (no lung there)
- Who does primary PTX mostly affect?
- tall, thin boys or young men, 10-30 yo; smoking inc's risk
- rupture of subpleural apical blebs due to high negative pleural pressure
- What is secondary PTX associated with?
- other lung diseases: pneumonia, TB, Cystic fibrosis, Asthma, COPD
- What is Catamenial PTX (a secondary type) associated with?
- onset of menses +/- 3-5 days and also intrathoracic endometriosis
- What is an important contemporary cause of PTX on mechanical ventilation
- Pulmonary barotrauma
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