Chapter 15: Respiratory System - Powerpoint

what are the components of the respiratory system?

* airway (conduction zone)
* lungs (respiratory zone)
* supporting systems (cardiovascular, musculoskeletal, immune)

what is pulmonary ventilation?

* from atmosphere to lungs
* no real exchange yet

what is alveolar gas exchange?

* from lungs to blood
* O2 in, CO2 out

whaat is gas transport?

* consists of pulmonary and systemic circulation

what is systemic gas exchange?

* internal respiration
* **O2**: from blood to tissues
* **CO2**: from tissues to blood

what is cellular respiration?

* from blood to cells
* aerobic (requiring oxygen)

what are the functions of the conduction zone?

1. warming of air
2. moistening air
3. filtering air

how does the conduction zone warm air?

* via nasal and oral pathways
* external temperature is different than body temperature (37 C)

how does the conduction zone moisten air?

* via nasal and oral pathways
* atmospheric humidity is extremely variable compared to body humidity (100%)

how does the conduction zone filter air from pathogens and irritants?

* contains ciliary epithelium that have submucosal glands and goblet cells which secrete saline and mucus, respectively, to trap particles
* clara and progenitor cells have chemicals that can detoxify
* mucociliary elevator

what is the role of goblet cells?

* secrete a sticky mucous over the saline layer (CFTR channel)
* contains immunoglobulins that secrete antibodies to fight pathogens

what is the mucociliary escalator?

* spit mucus out
* swallow mucus

what is the function of the mucociliary escalator and aqueous saline layer?

* Na+/K+ ATPase pump produces a sodium gradient for the NKCC
* NKCC symporter transports one Na+, one K+ and two Cl- into the respiratory epithelial cell
* cystic fibrosis transmembrane regulatory (CTFR) channel allow Cl- to enter the saline layer in the lumen
* Na+ travels from ECF to lumen via the paracellular pathway due to the electrochemical gradient
* NaCl travels from ECF to lumen which creates a concentration gradient that causes water to follow into the lumen

what is cystic fibrosis?

* genetic mutation of the CFTR channel (dysfunction)
* reduced saline layer causing a thick build-up of mucus
* increased resistance, decrease airflow
* restricts mucociliary escalator causing bacterial infections

what happens when there is a loss of ciliated columnar epithelial cells?

* smoker’s cough is defined as paralysis or destruction of columnar epithelia cells and clara cells resulting in restricted mucociliary escalator, thick mucus build-up, and loss of detox effects
* increased resistance, decrease airflow
* may cause lung damage

what are the cell types of the respiratory zone?

alveolar cells (type I, II and III)

what are type I alveolar cells?

involved in external respiration exchange

what are type II alveolar cells?

reduces surface tension to keep alveoli from collapsing or clapping against each other

what are type III alveolar cells?

aka macrophages that are involved in immune function

how is gas diffused to the cardiovascular system in the respiratory zone?

* the respiratory membrane has two cell layers: alveolar epithelium (type I) and capillary endothelium separated by the fused basal laminae
* connective tissue between alveoli consists off elastin and collagen which gives it the ability to return to its original position

what is the volume of pulmonary circulation?

* \~0.5 L
* pulmonary flow = systematic flow = \~0.5 L/min
* pulmonary arterial pressure = \~15/8 mm Hg

why is the pulmonary arterial pressure lower than systematic arterial pressure?

pulmonary arterial pressure is 25/8 mm Hg because they are short vessels, whereas, systematic arterial pressure is 120/80 mm Hg due to longer vessels

when vessel length decreases, resistance ____________

decreases (1)

when vessel compliance (stretchiness) increases, resistance _____________

decreases (2)

when diameter off arterioles increase, resistance ____________

decreases (3)

what does ventilation mean?

breathing

what is inhalation?

inspiration (breathing in)

what is exhalation?

expiration (breathing out)

what is the respiratory cycle?

* known as quiet breathing at rest
* inhalation is active meaning that the inspiratory muscles contract
* exhalation is passive meaning the inspiratory muscles relax

true/false: a respiratory cycle begins with an inhalation

true

what is the ratio of air supply to blood supply?

* ventilation (V) / perfusion (Q)
* average: 0.8

what is zone 1 (apex) of the ventilation (V) and perfusion (Q) ratio?

* when V/Q is **greater** than 1


* ventilation (V) being greater than perfusion (Q), it causes decreased blood flow

what is zone 2 (middle) of the ventilation (V) and perfusion (Q) ratio?

* when V/Q is **equal** to 1
* when ventilation (V) is approximately equal to perfusion (Q), blood flow is variable

what is zone 3 (base) of the ventilation (V) and perfusion (Q) ratio?

* when V/Q is **less** than 1
* when ventilation (V) is less than perfusion (Q), it causes an increase in blood flow

what is perfusion matching?

it is the balance between air and blood supply to alveoli

what is a normal ventilation (V) and perfusion (Q) ratio?

* health individual: 0.8
* zone 1: V/Q greater than 1
* zone 2: V/Q approximately equal to 1
* zone 3: V/Q less than 1

when an individual has normal ventilation (V) and perfusion (Q) ratio, what are the differences between the apex and base at **rest**?

* increased blood flow to **base**
* increased blood flow due to gravity
* increased hydrostatic pressure to keep vessels open

when an individual has normal ventilation (V) and perfusion (Q) ratio, what are the differences between the apex and base during **exercise**?

* increased blood flow to **apex**
* increased hydrostatic pressure to keep vessels open
* improves zone 1 V/Q ratio

a shunt is a result of V/Q ratio mismatch. why does it occur?

due to poor alveolar ventilation (V < Q)

what are examples of shunts?

pulmonary edema, pneumonia, inflammation, cystic fibrosis

what are local control mechanisms to correct shunts?

* decrease P_O2 in alveoli triggers vasoconstriction of the pulmonary arterioles to the alveoli with reduced function
* diversion of blood to capillaries around functional alveoli
* increase P_CO2 in alveoli triggers bronchodilation

alveolar (physiological) dead space is the result of V/Q mismatch. what causes it?

poor blood supply (V > Q)

what are examples of alveolar dead space?

pulmonary embolism, emphysema (fewer alveolar capillaries), cardiovascular shock (reduced CO), alveolar collapse

what are local control mechanisms to correct alveolar dead space?

* decrease CO2 in alveoli due to poor blood supply triggers bronchoconstriction of air ways
* diversion of air to functional alveoli
* increase O2 in alveoli triggers vasoconstriction of local arterioles to the alveoli with reduced function

what is the ideal gas equation?

PV=nRT

pressure x volume = ____________-

moles of gas x 8.3145 j/mol\*K x absolute temperature

when temperature and moles is constant, what is the equation?

V = 1/P

what is boyle’s law?

* P1V1=P2V2
* pressure and volume are inversely related

what is dalton’s law?

the total pressure of a mixture of gasses is the sum of the partial pressure of the individual gas

gas movement will follow ____________

pressure gradients

what is the bulk flow of air equation?

* F = deltaP/R
* F = air flow measured in L/min
* deltaP = gas pressure measured in mm Hg
* R: resistance measured in mm Hg/mL/min

how do you find deltaP?

deltaP = P_alv - P_atm

when the pressure of the alveoli (P_alv) is **equal** to the pressure of the atmosphere (P_atm), _____________________

no gradient is produced, thus no air movement

when the pressure of the alveoli (P_alv) **less** than the pressure of the atmosphere (P_atm) _____________________

air goes in (inhalation)

when the pressure of the alveoli (P_alv) is **more** than the pressure of the atmosphere (P_atm), _____________________

air goes out (exhalation)

when the airway radius increases, resistance _____________

decreases (bronchodilate)

when the airway radius decreases, resistance _____________

increases (bronchoconstrict)

what happens when quiet breathing (**inhalation**)?

* **diaphragm contracts** (pulls down)
* **rib cage expands** via external intercostals and scalenes
* when the thoracic cavity volume increases, internal pressures decreases

what happens when quiet breathing (**exhalation**)?

* **diaphragm relaxes** (pulls down)
* **rib cage relaxes** via external intercostals and scalenes
* when the thoracic cavity volume decreases, internal pressures increases

what is the mechanical factors in ventilation equation?

* C = delta V_L/deltaP
* C = compliance (ability to stretch)
* it is easier to stretch lungs without pressure

what is elastic recoil?

* lungs recoil inward
* chest wall recoil outward

what happens when lungs recoil inward?

* assists in exhalation
* opposes lung expansion
* due to collagen and elastin

what happens when chest wall recoils outwards?

* promotes lung expansion
* assists in inhalation

when the rib cage expands, the diaphragm contracts, and the lung volume increases. what happens to the pressure of the alveoli?

* decreases (P_alv < P_atm)
* air flows in (inhalation)

when the rib cage and diaphragm relaxes, the lung volume decreases. what happens to the pressure of the alveoli?

* increases (P_alv > P_atm)
* air flows out (exhalation)

what is the base atmosphere pressure (P_atm)?

always set at 0

what is the base intrapleural pressure (P_ip)?

* -3 to -6
* **inhalation**: increase volume = decreased pressure (more negative)
* **expiration**: decrease volume = increased pressure (less negative)

what is the base alveolar pressure (P_alv)?

* varies with volume
* **inspiration**: increase volume = decreased pressure
* **expiration**: decrease volume = increased pressure

what are the transmural pressures at rest?

* transpulmonary pressure (P_tp)
* chest wall pressure (P_cw)
* respiratory system pressure (P_rs)

what is transpulmonary pressure (P_tp)?

* it is the pressure across the wall of the lungs to hold them up and open to keep breathing


* alveoli always contain a small amount of air to keep alveoli and lungs from collapsing
* opposes elastic recoil of lungs

what is the transpulmonary pressure (P_tp) equation?

* P_tp = P_alv - P_ip
* 4 mm Hg = 0 - (-4)

what is chest wall pressure (P_cw)?

* it is the pressure holding the chest wall in
* opposes elastic recoil of chest wall
* prevents excessive expansion

what is the chest wall pressure (P_cw) equation?

* P_cw = P_ip - P_atm
* -4 mm Hg = -4 - 0

what is respiratory system pressure (P_rs)?

it is the driving force for air flow

what are the mechanics of inspiration?

* decreased respiratory system pressure
* it is the pressure gradient from atmosphere to alveoli
* **starting** inspiration: no air flow
* **during** inspiration: air flow moves into the lungs
* pressure in alveoli is less than pressure in atmosphere
* **ending** inspiration: no air flow

how does inspiration happen (**intrapleural pressure**)?

* contraction of inspiratory muscles (diaphragm, external intercostals, scalenes)
* increase thorax volume = increased intrapleural space volume = decreased intrapleural pressure

how does inspiration happen (**intrapulmonary pressure**)?

* it pulls against the elastic recoil of the lungs
* increase lung volume = decrease pressure of the alveoli = decreased respiratory system pressure

what are the mechanics of expiration?

* increased respiratory system pressure
* pressure gradient from the atmosphere to alveoli
* **starting** expiration: no air flow
* **during** expiration: air flows out of the lungs
* pressure in alveoli is greater than pressure in atmosphere
* **ending** expiration: no air flow

when there is no air flow, there is no ______________

pressure gradient

how does expiration happen (**intrapleural pressure**)?

* relax inspiratory muscles (diaphragm, external intercostals, scalenes)
* decrease thorax volume = decreased intrapleural space volume = increased respiratory system pressure

how does expiration happen (**intrapulmonary pressure**)?

* stop pulls against the elastic recoil of the lungs
* decrease volume of lungs = increased pressure of alveoli = increased respiratory system pressure

what is quiet breathing?

* inhalation
* requires stimulation and use of the diaphragm, external intercostals, and scalenes
* respiratory rate is greater than 12-20 breaths/min
* exhalation
* does not require stimulation, lets muscles relax

what is deep breathing?

* inhalation
* requires stimulation and uses sternocleidomastoid and more effort from external intercostals
* exhalation
* does not require stimulation, but uses abdominal muscles and internal intercostals

what is a pneuomothorax?

air in pleural cavity when it SHOULD be sealed

what would be the cause of an **open pneumothorax**?

injury outside of the body such as sucking chest wound

what would be some causes of a **closed pneumothorax**?

* damage from inside the lungs
* examples: mechanical ventilation injury (typically in kids/infants), damage from broken ribs, or spontaneous pneumothorax (assoc. with lung diseases)

when pressure gradients are lost, what happens?

collapsed alveoli (atelectasis)

what are the **four** lung volumes?

1. tidal volume (TV)
2. inspiratory reserve volume (IRV)
3. expiratory reserve volume (ERV)
4. residual volume (RV)

what are the **four** lung capacities?

1. functional residual capacity (FRC)
2. inspiratory capacity (IC)
3. vital capacity (VC)
4. total lung capacity (TLC)

how do you find functional residual capacity (FRC)?

ERV + RV

how do you find inspiratory capacity?

TV + IRV

how do you find vital capacity?

TV + IRV + ERV

how do you find total lung capacity?

TV + IRV + ERV + RV

what is peak expiratory flow (PEF)?

* how much you can exhale per time
* exhalation of VC: L/min
* varies with age and size
* diagnostic tool for ventilation & potential lung function

what factors influence ventilation?

1. recoil
2. compliance
3. alveolar surface tension
4. airway diameter of the bronchioles

how does recoil affect ventilation?

* it is necessary for expiration and impacts peak expiratory flow
* if having difficulty exhaling, then it can lead to chronic obstructive pulmonary diseases such as emphysema

how does compliance affect ventilation?

* necessary for inspiration
* if having difficulty w/ compliance, then it can lead to restrictive lung diseases such as pulmonary fibrosis
* lack of surfactant can make it harder for lungs to expand due to surface tension

how does alveolar surface tension affect ventilation?

* effect of alveolar diameter
* if the diameter of alveoli is small, then there is an increase in surface tension allowing for more ability to recoil and decrease compliance making it difficult to expand
* consequence: small alveoli are more likely to collapse & stick together

how does airway diameter of the bronchioles affect ventilation?

* increase in transpulmonary pressure = pulls open alveoli and small bronchioles = decrease resistance
* decrease in transpulmonary pressure = allows recoil in alveoli and small bronchioles = increases resistance

what is the parasympathetic system’s role in airway diameter?

* bronchoconstriction = decreased diameter = increased resistance
* innervation with ACh and mAChR in smooth muscle
* paracrine agents trigger mast cells that secrete histamine and **decreases** CO2 in airway causing bronchoconstriction