lung mechanics: pressures acting on systems

explain pulmonary ventilation versus alveolar ventialation and how to calculate them

pulm: gross ventilation per minute (tidal colume x RR)

alveolar: fresh air reaching gas exchange areas of the lungs [(tidal volume-dead space)-RR]

expalin inahlaton and exhalation with regards to diaphragm movement and rib movement

inhalation: air flow in, ribs move up and out, diaphragm flattens

exhalation: air flows out, ribs move down and in, diaphragm domes up

muscle of inspiration: principle and accessory

principal: external intercostals, interchondral part of internal intercostals, diaphragm

accessory: sternocleidomastoid, anterior, middle, and posterior scalenes

in resting breathing, inspiration is ____ and expiration is _____

inspiration active

expiration passive

in vigorous breathing, inspiration is ____ and expiration is _____

both are active

muscles of expiration: quiet breathing vs active breathing

quiet: passive recoil of lungs

active: internal intercostals, abdominal muscles, rectus abdominus, external and internal obliques, transversus abdominus

what are the factors (4) affecting diaphragm function. How do they affect it?

paradoxical movement, ascites, pregnancy, and obesity

they decrease it

explain intrapleural pressure at the apex of the lung versus the base of the lung

higher negative pressure at the apex than the base because of gravity (less pressure at the top; like a swimming pool)

explain a pneumothorax and intrapleural pressure

pleural pressure that is usually negative becomes zero or positive

What is alveolar pressure at rest?

how does it change with inspiration and expiration?

at rest: 0

inspiration: -1

expiration: +1

pressure and volume are inverse

What is transpulmonary pressure? how do we calculate it?

pressure across the outer surface of the lungs

equation: pressure inside (alveolar) - pressure outside (intrapleural)

what is the measure of the elastic forces in the lungs that tend to collpase the lungs at each instant of respiration

recoil pressure

What happens to intrapleural pressure with forced exhalation?

it gets positive

obstructive lung disease: loss of ability to develop ____ alveolar pressure

positive

Restrictive lung disease: loss of ability to develop ___ alveolar pressure

negative