KIN 300 - Ch 7

pulmonary ventilation

moving air in and out of lungs; breathing

regulated by changing thoracic volume

pulmonary diffusion

moving oxygen into the blood and carbon dioxide out of the blood

gas transport

movement of blood containing gases

• oxygen traveling in blood from lungs to tissues

• CO2 from tissues to lungs

capillary gas exchange

exchange of gases: oxygen to tissues, CO2 away from tissues

cellular respiration

oxygen use in aerobic metabolism and CO2 production within tissues

pathway of air starting from outside to lungs (only know 3)

R and L lungs to bronchioles to alveoli

bronchioles function

can dilate/constrict to adjust opening of airway

narrow = increased resistance, less air

what’s exchanged at alveoli from blood into air

CO2

what’s exchanged at alveoli from air into blood

O2

flow of air: diaphragm and external intercostals contract, thoracic volume increases, pressure falls below atmospheric

inspiration

lungs function

elastic recoil to push air out, return to shape

maintain flow of air in and out of lungs

alveoli function

large surface area to maximize diffusion area

thin membrane and constant blood flow

Boyle’s Law

pressure is inversely proportional to volume

*ALWAYS flows from high to low pressure

functions of respiratory system

moves air in/out of lungs

gas exchange between air & blood

filters, warms, and humidifies air

lung volume range

4-6 L (depending on height, sex, age)

alveoli function

exchange site for O2 and CO2

allow for diffusion on their surface

name 2 membranes that aid diffusion in respiratory membrane

• membrane of alveolar cells

• membrane of cells of capillary wall

purpose of pleural fluid

reduces friction during respiration

intrapleural pressure

keeps lungs from collapsing

has to be less than atmospheric pressure

describe inspiration (intrapulmonic pressure, lung volume, direction of air)

>lung volume

<intrapulmonic pressure

air flow into lungs

describe expiration (intrapulmonic pressure, lung volume, direction of air)

<lung volume (elastic recoil)

>intrapulmonic pressure

air flow out of lungs

most important inspiratory muscle

diaphragm: flattens and contracts to allow more room for resp

inspiration: passive or active

active- muscles contract

quiet exhalation: active or passive

passive - no muscle contraction needed

forced exhalation: active or passive

active - contract internal intercostals & abd muscles

push diaphragm up/pull ribs down

main stimulus for breathing rate

chemoreceptors detect rising blood CO2, pH decreases as result

mechanism of inspiration

ribs rise

diaphragm lowers

chest cavity size increases

lungs expand

mechanism of expiration

ribs lower

diaphragm rises

chest cavity size decreases

lungs recoil

exercise: muscles that assist during forced inspiration

anterior, middle, posterior scalene and ext intercostals work to RAISE RIBS MORE than regular breathing

exercise: muscles that assist during forced expiration

internal intercostals, rectus abd, internal oblique work to contract & pull ribs downward

what affects airflow

resistance and pressure difference between 2 areas

airflow equation

airflow = (P1-P2)/resistance

how can you increase airflow

decrease the resistance or increase the pressure

at rest: biggest factor affecting airflow

diameter of airway

exercise: how do we decrease resistance to airflow

mouth breathing: wider diameter

sympathetic stimulation = bronchodilation

minute ventilation (VE)

amount of air breathed each minute

VE equation

VE (L/min) = TV (L/breath) x breathing rate (breaths/min)

Tidal volume (TV)

air moved in/out during normal quiet breath

approx TV value in healthy individuals

0.6 L men, 0.5 L women

Inspiratory reserve volume (IRV)

air that can be forced in after normal inhalation

Expiratory reserve volume (ERV)

extra air can be forced out after normal exhale

RV (Residual volume)

air remaining in lungs after forced exhale

vital capacity (VC)

max air that can be exhaled after max inhalation

Vital capacity equation

TV + IRV + ERV = VC

Total lung capacity (TLC)

vital capacity + residual volume

Minute ventilation eq

TV x Resp rate

two components of pulmonary ventilation

• anatomical dead space (air that doesn’t reach alveoli)

• alveolar ventilation (air that DOES)

alveolar ventilation eq

VE = VA x VD

how much of TV constitutes the anatomic dead space

150 - 200 mL (30%)

rest: which part of lungs receives more ventilation & why

basal parts of lungs - not necessary to use full surface area at rest

exercise: how much of lungs receives ventilation & why

basal & apical portions receive ventilation - need to use greater surface area for gas exchange

how does Fick’s law predict factors of diffusion

>surface area, pressure gradient, gas solubility, thinner membrane => increase diffusion

exercise: what changes (and order) to regulate breathing as intensity increases?

first increase depth of breaths (increases gas exchange)

then increase frequency of breathing

static lung volume tests

tests dimensional component for air movement (no time limit)

dynamic lung volume tests

evaluate power component of pulmonary performance during different ventilation phases (FEV1 tests in 1 sec)

why does lung volume decrease with age

decreases in lung tissue elasticity

decreases in physical activity

can exercise increase static lung volumes?

not really - mostly genetics

high intensity exercise: when TV begins to plateau, what factor is most important?

frequency of breathing - only way to get more air in

driving force for gas exchange

PO2 and CO2 between air in alveoli and blood

what aids gas diffusion at the capillary level and at lungs?

large surface area of alveoli

thinner of resp membrane

Dalton’s law

total pressure = P1+ P2+P3

each gas moves according to its own individual pressure gradient

partial pressure eq

partial pressure = % concentration x total pressure of gas mixture

ambient air partial pressure calculation

% concentration x 760 mmHg for O2, N2 and CO2

alveolar air partial pressure calculation

% x (760-47) for O2, N2, CO2

Fick’s law

volume of gas diffusing is proportional to

1. surface area available for diffusion

2. diffusion coefficient of each gas

3. difference in partial pressures

Henry’s law

amount of gas dissolved in a fluid depends on temperature, solubility of gas in the fluid, and partial pressure of the gas

if gas’s solubility in the blood is constant and temp is constant, factor for gas exchange between alveoli and blood?

pressure gradient between the gases!

when does net diffusion of gas occur?

when difference in gas pressure exists

PCO2 at sea level

0.2 mmHg

PCO2 in alveoli

40 mmHg

PCO2 in arterial blood entering lungs

46 mmHg

PCO2 in blood leaving lungs

40 mmHg

PCO2 in tissues

46 mmHg

for each unit of pressure favoring diffusion, approximately HOW MUCH more CO2 than O2 moves into/from a fluid?

25 times

3 ways to increase venous return

1. venoconstriction of inactive muscles

2. respiratory pump

3. skeletal muscle pump

skeletal muscle pump

contraction of muscles pushes blood back up

respiratory pump

diaphragm contraction during respiration pushes blood back up

as ____ increases, more total gas diffusion can take place (ex. during exercise!)

as blood flow increases

how long does it take to reach equilibrium between alveoli air and lung capillary blood

0.25 seconds

what decreases the time it takes to reach equilibrium between alveoli air and lung capillary blood?

exercise! blood flow increases so it’s speedy

when blood flow increases, how is optimal oxygen diffusion maintained?

• uses greater portion of lung’s alveoli

• preservation of thin resp membrane

  • increase in PO2 due to increase in pulmonary ventilation

when blood leaves heart towards peripheral, arrives at muscles with __% O2 saturation (20 mL O2/ 100 of blood)

100% saturated

blood drops off O2 at working muscles. when it’s sent back in venous circulation, what % remains saturated? and what % was dropped off?

25% remaining, 75% dropped off

adaptation during exercise in order to keep blood fully saturated?

use entire surface area - greater diffusion gradient bc of greater pressure differential

metabolic demands of ventilation at REST

very little energy

resp muscles operate with high efficiency

metabolic demands of ventilation at MAX EXERCISE

increase in metabolic rate, alveolar ventilation increases to maintain arterial blood gas homeostasis (PaO2 and PaCO2)

ventilatory adaptations to training

• optimize gas exchange

• lower energy cost of breathing

• delay fatigue

during exercise, Q increases. how does optimal oxygen diffusion continue during this?

• more capillaries recruited to INCREASE TOTAL capillary blood volume

• line adding lanes during high traffic hours to keep flow constant

• TRUE for untrained & mod. trained people

exception to optimal oxygen diffusion during exercise

highly trained endurance athletes can reach such high Q that gas exchange/volume of blood decreases (Exercise induced arterial hypoxemia)