Mechanics of Breathing

Phys

respiratory system functions

1. exchange of gases between atmosphere and blood

2. homeostatic regulation of body pH

3. protection from inhaled pathogens and irritating substances

4. vocalization

upper respiratory tract

mouth, pharynx, and larynx

lower respiratory tract

trachea, primary bronchi, bronchioles

number of lobes in the left lung

2

number of lobes in the right lung

3

pleural sacs

enclose lungs to thoracic cage, creates seal

alveoli

air sacs, site of gas excahnge

thoracic cage

spine, ribs, diaphragm, and intercostals

3 purposes of airways

1. warm air to body temp

2. add water vapor

3. filter out foreign material

Type I alveolar cells

perform gas exchange

Type II alveolar cells

surfactant production

ventilation flow usually matches_____

blood flow

resting on top of the alveoli

capillaries

Ideal Gas Equation

as volume increase, pressure decreases — and vice versa

D

Dalton’s Law

total sum of gas equals sum of partial pressures

gas pressure of oxygen at sea level

160 mmHg

Boyle’s Law

inverse relationship between pressure and volume

respiratory cycle

one breath in and one breath out

tidal volume

volume of air with normal, quiet volume

inspiratory reserve volume

inhale more air than during normal breath

expiratory reserve volume

all additional air you can exhale after normal breath

residual volume

air left in your lungs that you cannot remov

vital capacities

voluntary air movement

total lung capacity

all air

larger humans have ___ lung volumes and capacities

greater

pressure gradients

flow is proportional to pressure and inversely proportional to resistance

expiration

passive process

intrapleural pressure

pressure that creates vacuum between pleural lining and inside of thoracic cage

intrapleural pressure at rest

-3 mmHg

intrapleural pressure during inspiration

-6 mmHg

pneumothorax

collapsed lung due to air in thorax

Law of LaPlace

pressure is equal to twice the time of tension divided by resistance

surface active agents

breaks up/disrupts cohesive forces of water, puts tension on alveoli and increases compliance

NRDS

Newborn Respiratory Distress Syndrome, not making own surfactant

compliance

ability of tissue to stretch

emphysema

lung tissue can stretch but no recoil; blood fills with carbon dioxide because no exhale

cystic fibrosis

not enough compliance

elastance

ability to recoil

bronchoconstriction

airways narrow, parasympathetic influence

asthma

overreaction to bronchoconstriction

bronchodilation

airways widen; decrease resistance to air flow, sympathetic influence

anatomic dead space

150 mL air stuck in conducting airways and can’t undergo exchange (decreased efficiency)

alveolar ventilation

volume of air that reaches alveoli per minute (5 L/min)

maximum voluntary ventilation

170 L/min

partial pressure of oxygen in lungs

100 mmHg

partial pressure of oxygen in tissues

40 mmHg

partial pressure of carbon dioxide in lungs

40 mmHg

partial pressure of carbon dioxide in tissues

100 mmHg

emphysema

can cause paralysis of cilia; elastin destroyed by macrophages; problems with securing secretions and exhalation; more erythropoietin and increased hematocrit