pulmonary anatomy and physiology review

what is ventilation?

moving air in and out of the lungs

what is respiration?

gas exchange, diffusion of O2 and CO2 from the air to the blood to the tissue

what is a normal substernal angle?

90 degrees

over 90 degrees may mean hyperinflated lungs, barrel chest or COPD

what are the two main muscles of inspiration?

diaphragm and external intercostals

which muscle does 70-80% of the work of inspiration?

diaphragm

what happens to the diaphragm during inhalation?

it flattens, descends and the intrathoracic cavity increases in size

what happens when the external intercostals contract?

the ribs move up and out

what are the four accessory breathing muscles?

SCM, scalenes, upper traps and pec major/minor

how does the SCM assist in breathing?

it elevates the sternum and lifts the ribs when the head is fixed. used for heavy breathing like in athletes

how do the scalenes assist in breathing?

elevates the ribs

what do both the upper trapezius and pec major/minor do with breathing?

help elevated the rib cage and increase the diameter of ribs

are the muscles of expiration mostly active or passive?

mostly passive due to the elastic recoil and relaxation of the external intercostal muscles and diaphragm

what are the muscles used for forced expiration (blowing out a candle)?

abdominals and internal intercostal muscles, they decrease the size of the ribcage

what happens during inhalation?

the rib cage expands as rib muscles contract, and the diaphragm contracts and moves down

what happens during exhalation?

rib cage gets smaller as rib muscles relax, diaphragm relaxes and moves up

what is pump handle movement?

during inspiration the sternum moves superiorly and anteriorly , the upper ribs elevate, which increases the AP diameter of the thorax

what is bucket handle movement?

during inspiration lower ribs move laterally, elevates and moves outward, and increases the tranverse diameter of the thorax

during inspiration what are the pressures like?

the intrathoracic pressure is lower than the atmospheric pressure, so the air goes in

during expiration what are the pressures like?

the inrathoracic pressure is higher than the atmospheric pressure, so the air goes out

what is the impact of sitting/standing on the diaphragm?

gravity pulls the abdominal organs allowing the diaphragm to descend, so it is easier to take a big breath

what is the effect of being supine on the diaphragm?

abdominal organs press upward against the diaphragm which decreases lung volume and increases the work of breathing, harder to get a big breath

what is the effect of sidelying on the diaphragm?

dependent (lower) hemidiaphragm is pushed upward into chest cavity

what is compliance?

the lung’s ability to stretch and expand during inspiration

what is decreased compliance?

lungs are stiff which means a reduced ability for the lungs to stretch and expand during inhalation, fibrosis/pneumothorax

what is increased compliance?

it refers to the lung’s ability to stretch easily, COPD

what is lung elasticity (elastic recoil)?

the ability for lungs to spring back to original size

if there is an increased elasticity, what happens to compliance?

it decreases and vice versa

if there is increased surface tension what happens to compliance?

it decreases and vice versa

when airway diameter gets smaller, what happens to resistance?

it increases the airway resistance

does laminar flow increase or decrease airway resistance?

it decreases airway resistance

does turbulent flow increase or decrease airway resistance?

increase airway resistance

if lung volume increases does airway resistance increase or decrease?

decreased resistance and vice vers

what innervates the diaphragm?

phrenic n. C3,4,5 keeps the diaphragm alive!!!!!!

what innervates the intercostal muscles?

thoracic spnial nerves

what innervates the abdominal muscles?

T7-12 L1, spinal n

what happens if your patient has a C2 SCI?

both diaphragms dont work, not able to cough

what happens if your patient has a T1 SCI?

intercostals and abdominal muscles dont work, so you cough, breath more and are more at risk for pneumonia

what does the sympathetic nervous system do with breathing? FIGHT OR FLIGHT

beta 2 (airway muscles) and alpha 1 receptors (blood vessels)

bronchodilation of airways

vasoconstriction of blood vessels

reduced muscus production (dont want spit when youre in trouble)

what does the parasympathetic nervous system do with breathing? REST AND DIGEST

release of ACh to bind to M3 muscarinic receptors

bronchoconstriction of airways

vasodilation of blood vessels

increased mucus production

which side of the conducting zone is more common for respiration pneumonia?

the right side, it is more vertical

what is the conducting zone?

the mouth to the terminal bronchioles

functions: filters and cleans air, warms and humidifies air

anatomic dead space: volume 150-200 mL

just moves point A to point B

what is the mucociliary escalator?

• primary defense of the respiratory system

• sticky layer of mucus to trap inhaled dust, pathogens as well as cilia to sweep the debris back towards the throat

• smoking can have a negative impact

goblet cells

line the airways and secrete mucus

Cilia

microscopic, hairlike projections that line the mucous membrane

what is the respiratory zone?

• consists of respiratory bronchioles and alveoli

• region of gas exchange which occurs by diffusion

what are alveoli?

• where gas exchange takes place

• 300-600 million air sacs

• large blood supply

what are the pores of kohn?

interchange of gas between two alveoli, indirect ventilation

what is surfactant?

it decreases the surface tension so the alveoli dont collapse

does the pulmonary artery have oxyegenated or deoxygenated blood?

deoxygenated blood!

what is the blood supply to the lungs?

pulmonary circulation and bronchial circulation

what is the visceral pleura?

the inner pleura

what is the parietal pleura?

the outer layer of pleura

what is the intrapleural space?

it decreases friction, keeps airways and lungs open

what is pleuritis?

infection, broken ribs, sharp pain w breath/cough

what is pleural effusion?

too much fluid in the pleural space

what is hemothorax?

blood in the pleural space

what is a pneumothorax?

air in the pleural space, lung collapse

what is empyema?

pus/infection in the pleural space

what is minute ventilation?

volume of air that moves in/ out of the lungs each minute

what is alveolar ventilation?

volume of air that ventilates only the alveoli

the amount of fresh inspired air available for gas exchange

V_A=(TV - DEAD SPACE) X RR

determines the gaseous concentrations at the alveolar-capillary membrane

maintained during exeercise by an increase in rate and depth of breathing

VA increases with an increase in CO2 production

what is the equation for minute ventilation (VE)?

RR x TV

resp rate x tidal volume

what increases minute ventilation?

exercise

what is shallow breathing tidal volume?

300 mL, ex. is abdominal surgery

what is deep breathing tidal volume?

1000 ML

what is the ventilation and perfusion ratio?

normal: 4L/5? =.8 L which is an optimal O2 transfer

exercise can cause an increase to 5L

what happens with a V/Q mismatch?

it can result in impaired gas exchange leading to hypoxia

what does a V/Q scan do?

it is used to visualize and measure airflow and blood flow in the lungs

what is the clinical significance of the V/Q ratio?

V/Q mismatch is when certain areas of the lungs are not optimally exchanging O2/CO2 due to inadequate ventilation or blood flow. this leads to impaired gas exchange/hypoxiawh

what is a shunt?

low VQ ration, under .8.

LOW V AND NORMAL Q

pneumonia, atelectasis, pulmonary edema

what is dead space?

Normal V and low Q ration over .8

pulmonary emboli

what are symptoms for shunt and dead space?

increased RR, SOB, fatigue, headache, confusion, dizziness and cyanosis

what is ambient air composition?

Oxygen: 20.93%

nitrogen: 79.04%

carbon dioxide: 0.03%

what is partial pressure?

partial pressure=% of concentration of specific gas x total pressure of gasw

what is partial pressure of ambient air?

159 mmHg

what is henry’s law?

gases diffuse from high pressure to low pressure

what does diffusion rate depend on?

pressure differential and solubility of the gas in the field

what impairs gas transfer capacity?

thickened alveolar will and capillary membrane, it is usually thin, so it takes longer for O2 to get into the capillary when thick

decreased alveolar surface area, COPD reduced # of alveoli

what is the less common way that oxygen is transported through blood?

dissolved in blood (2-3%)

• function of dissolved O2

  • establishes the PO2 of the blood and tissues

  • regulates breathing

  • involved in the unloading of O2 from hgb

what is the main way that oxygen is transported through the blood?

attached to hemoglobin (97-98%)

what is the main component of RBC?

hemoglobin

how many oxygen molecules does a hemoglobin carry?

4

what are the normal values of hemoglobin in men?

15-16 g/dL

what are the normal values of hemoglobin in women?

14 g/dL

what is blood’s O2 carrying capacity?

each gram of Hb can combine with 1.34 mL of O2

what is anemia?

• occurs when blood Hgb is below normal

  • common symptoms: fatigue, headache, dizziness, lack of concentration, rapid/irreg HR, pale nail beds/skin/gums

what are treatments for anemia?

RBC transfusion

iron (but can lead to constipation)

erythropoietin protein medications

what does high altitude training do to hgb and O2?

less O2 which tricks body to make more hgb

what are erythropoiesis stimulating agents?

medications that stimulate production of RBC in bone marrow

procrit, epogen and aranesp: but have blood clot side effects

approved by FDA in 1989, as a treatment of anemia due to CKD, chemo, and after a major surgery

it was used in athletes to enhance performance but was banned in 1990

what is pulse oximetry?

it indirectly measures the O2 saturation of a person’s blood, the % of HgB molecules bound with O2 molecules (SpO2)

IT MEASURES OXYGENATION NOT VENTILATION

what are the limitations of pulse oximetry?

• hypoventilation—> high CO2 —> respiratory acidosis (but the pulse ox looks normal)

• decrease in blood flow or low Hgb the tissues may be hypoxic

• if Hgb binds to something other than oxygen

whats the normal value for pulse ox?

above 93 percent

what causes false readings on pulse ox?

nail polish, raynauds, calluses

what symptoms may you see with a low pulse ox value?

grey lips, difficult breath, finger color

what is affinity?

the strength with which the hemoglobin binds to oxygenw

what is increased affinity?

when Hgb holds onto the O2

what is decreased affinity?

the Hgb releases the O2

what four factors effect the oxygen hemoglobin dissociation curve?

temperature, acidity, CO2 concentration, 2-3 DPGw

what happens if the four factors that effect the O2-Hgb curve increases?

affinity decreases, a right shift occurs, and more O2 is offloaded

what is Bohr’s effect?

increase plasma acidity which decreases PH

increase CO2 concentration

results in a decreased affinity of Hgb for O2 which means it is easier to offload O2 to the tissue

what happens when there is an increase in 2-3 DPG?

decreased affinity, from high altidude, chronic lung disease and anemia