Exercise Physiology Final Exam LeeAnn Joe

What is the main function of the respiratory system?

gas exchange; helpings regulate acid-base balance

What are the 4 processes of the respiratory system?

pulmonary ventilation

pulmonary diffusion

transport of O2 and CO2 via the bloodstream

capillary gas exchange

What is external respiration?

refers to the exchange of gases between the atmosphere and the blood through the alveoli

What is internal respiration?

refers to the exchange of gases between the blood and the tissues

When is the mouth used in respiration?

when the demand exceeds nasal capacity

Air entering the nasal cavities swirls through the irregular surfaces (_______________) lined with __________ and __________.

nasal conchae; mucus; cilia

What 3 things must happen to air by the time it reaches the lungs?

it is warmed to 37 C, humidified to 100% RH, and filtered of particles

Are all air passages lined with cilia and mucus?

yes

What do the cilia beat toward?

the larynx

What is the pharynx?

throat; free passage of air and food

What is the larynx?

voice box composed of 9 cartilages

What is the lid on the larynx that stops food from entering?

epiglottis

What happens if food or drink particles get past the epiglottis?

a cough reflex is initiated

What is the trachea?

4-inch non-collapsible tube (windpipe) that connects the larynx to the bronchi

Why are the rings of cartilage surrounding the trachea C-shaped?

to allow the esophagus to expand when swallowing

What are 1° bronchi?

where the trachea splits and plunges into the lungs

How many 1° bronchi are there?

2; R and L 1° bronchi

How do the bronchi divide?

1° bronchi > 2° bronchi > 3° bronchi > bronchioles

What are bronchioles?

branches off the bronchi

What are terminal bronchioles?

smallest bronchioles

What are respiratory bronchioles?

terminal bronchioles that have alveoli leading directly off of them

What are alveolar ducts?

small ducts leading from terminal bronchioles which have clusters of alveoli extending off of them

What is the conducting zone?

the larger airways that warm, humidify, and filter air without participating in gas exchange (i.e. anatomic dead space)

What is dead space ventilation?

volume of air remaining in conducting airways

What is the respiratory zone?

the airways participating in gas exchange; contain alveoli

What are alveoli?

small, elastic, thin-walled membranous sacs that allow for gas diffusion

How many alveoli are in the lungs? What is the combined surface area?

over 600 million; 85 m²

Alveoli are lined with what?

a thin layer of fluid

What is the visceral pleura?

serous membrane that covers lungs

What is the parietal pleura?

lines the walls of the thoracic cavity

Is the intrapleural pressure lower or higher that barometric pressure?

lower

What is the function of serous fluid in the lungs?

eliminates friction

indirect connector

What is the formula for airflow?

airflow = ΔP / Resistance

What is the gas law?

v = 1/P

Breathing is a mechanical process, so it depends on the _________ of the thoracic cavity and lungs due to _____________ ______________.

ΔV; muscular contraction

What muscles cause inspiration during rest?

contraction of the diaphragm (lowers it) and external intercostals (expands ribcage)

What muscles cause expiration during rest?

relaxation of the diaphragm (raises it) and external intercostals (collapses ribcage)

What additional muscles are recruited for inspiration during exercise (these pull the ribcage up and back)?

sternocleidomastoid

scalene muscles

pectorals

serratus anterior

trapezius

What additional muscles are recruited for expiration during exercise?

internal intercostals: collapse ribcage (may be assisted by latissimus dorsi and quadratus lumborum)

abdominals: push diaphragm up further

What is the resting breathing rate?

f = 12 br/min

What is the exercise breathing rate?

f = up to 70 br/min

What does the thin layer of fluid on the alveolar surface do?

creates surface tension

What is the law of LaPlace?

P = 2ST/r

(ST: surface tension)

What is surfactant?

phospholipid secreted by type II alveolar cells

What is the function of surfactant?

decrease surface tension and help lungs expand during inhalation

What happens if excess fluid enters the interstitial space?

diffusion cannot occur

What is hydrostatic pressure (HP)?

pressure exerted outwards from blood on the capillary wall (15 mmHg)

What is colloid osmotic pressure (COP)?

pressure caused by proteins in blood that creates a force that pulls fluid from interstitium into capillary (25 mmHg)

As long as _______ > _______, interstitial space stays dry, and diffusion freely occurs along concentration gradients.

COP > HP

If _______ > ________, interstitium becomes wet and hampers diffusion.

HP > COP

What are the laws of diffusion?

diffusion is proportional to surface area

diffusion is proportional to 1/thickness of alveolar membrane

diffusion is dependent on a partial pressure gradient

What is the goal of diffusion?

equilibrium

What is Dalton's Law?

the total pressure of a gas mixture is equal to the sum of the partial pressure of each gas in the mixture

What is the formula for Dalton's law?

Ptotal = P1 + P2 + P3...

What is partial pressure of a gas?

pressure that a gas exerts independently in a gas mixture

What percentage of dry air is O2?

20.93%

What percentage of dry air is CO2?

.03%

What percentage of dry air is N2?

79.04%

What percentage of dry air is H20?

0%

What are actual alveolar partial pressures somewhat different from calculated alveolar partial pressures?

because air entering the lungs mixes with residual lung volumes (RLV)

What is PaO2 at sea level?

100 mmHg

What is PvO2 at sea level?

40 mmHg

How do the rate of flow and pressure of blood in the pulmonary circuit compare to that of the systemic circuit?

pulmonary circuit has the same rate of flow but lower pressure

Where does most of the blood flow go in the lungs while standing?

to the base due to gravity

During exercise what happens to blood flow in the lungs?

blood flow is increased to the apex

*ventilation-perfusion ratio

What percentage of O2 is dissolved in plasma?

2%; this establishes PO2

What percentage of O2 is bound to Hb?

98%; dependent of PO2

What is cooperative binding in Hb?

Hb changes conformation with unloading/loading of O2

As Hb binds an O2, Hb more readily binds more O2.

As Hb offloads O2, O2 more easily offloads from Hb.

What does the HbO2 dissociation curve depict?

the binding strength between O2 and Hb based on PO2

What factors influence the HbO2 dissociation curve?

pH

temperature

CO2 concentration

How does CO poisoning occur?

CO has a high affinity (240X) for O2 binding site on Hb. A small amount can cause death via hypoxia. Any CO present binds to Hb, kicking O2 out. If too little O2 is left to sustain life, death occurs.

What is myoglobin (Mb)?

protein found in muscles that shuttles O2 from the cell membrane to the mitochondria

Does myoglobin (Mb) have a higher affinity for O2 than Hb?

yes

When does myoglobin (Mb) discharge oxygen?

only at very low PO2; this allows myoglobin to store O2

What percentage of CO2 is dissolved in plasma?

10%

What percent of CO2 is bound to Hb?

20%

What is it called when CO2 is bound to Hb?

carbaminoHb

What is the Haldane effect?

when the offloading of CO2 from Hb facilitates O2 binding to Hb

70% of CO2 is transported as what?

bicarbonate ion (HCO₃⁻)

What is the carbonic anhydrase reaction?

CO2 + H2O <-> H2CO3 <-> H+ + HCO3-

How do central chemoreceptors regulate respiration?

they respond to increased PCO2 and H+ of CSF, which causes increased respiration

How do peripheral chemoreceptors regulate respiration?

they are sensitive to decreased O2, increased PCO2, and increased H+ concentration which causes increased respiration

Where are central chemoreceptors located?

cerebral medulla

Where are peripheral chemoreceptors located?

aortic arch (aortic bodies) and bifurcation of common carotid artery (carotid bodies)

Carotid bodies are also sensitive to increased _____________ and decreased ____________

blood K+ levels; arterial PO2

What is the strongest stimulus to breathe?

increased PCO2; hypercapnia

How do chemoreceptors in muscle regulate respiration?

they are sensitive to increased H+ and K+ concentration which causes increased respiration

What is the Hering-Breuer reflex?

reflex when stretch receptors in walls of pleurae, bronchioles and alveoli are stretched, respiration is decreased

What does the Hering-Breuer reflex prevent?

overinflation of the lungs

Can the cerebral motor cortex send signals to the respiratory center to consciously control breathing?

yes

Voluntary control of respiration can be overridden by what?

involuntary control

How do proprioceptors regulate respiration?

when muscle spindles, GTOs, and joint kinesthetic receptors detect movement, CNS increases respiration

How does local hypoxia regulate respiration?

if an area of the body experiences hypoxia, the CNS increases respiration

How does the SNS regulate respiration?

SNS stimulation causes bronchodilation, allowing more air to pass through per unit time

no PNS stimulation to respiratory system

How does body temperature affect respiration?

increased body temperature causes increased respiration

What does pulmonary ventilation during exercise look like?

at the onset of exercise, immediate marked rise in ventilation due to body movements followed by a gradual rise due to changes in temperature and chemical concentrations

How long does breathing take to get to normal post-exercise?

a few minutes due to EPOC

Does ventilation increase in proportion to exercise intensity?

yes

Why do few pulmonary adaptations to training occur?

because the cardiovascular system is the primary limiter of performance, not the respiratory system