Respiratory - Chapter 21

Basic functions of respiratory (conducting zone)

Conducting zone (moving one place to another ex. air)

• filtration

• warmth moisture

• warmth

Basic functions of respiratory (respiratory zone)

• gas exchange (where alveoli’s are)

Respiration 4 function:

pulmonary ventilation - movement of air in and out lungs

pulmonary gas exchange - movement of gases between lungs and blood

gas transport - movement of gases through blood

tissue gas exchange - movement of gases between blood and tissues

not respiration

• speaking

• smelling

• maintaining ph

• regulating internal pressure

  • lymphatic drainage

  • childbirth

  • moving blood around

  • excreting waste

Bronchioles

smallest airways

simple cuboidal epithelium

• enclosed within thick ring of smooth muscle

• conducting zone ends at terminal bronchioles

lungs hormone

angiotensin converting enzyme

Flow of air

nares - nasal cavity - nasophrynz - oropharynx - laryngopharynx - larynx - trachea - primary bronchi - secondary bronchi

Type 1 alveolar cells

• simple squamous

• 90% of lung cells

• rapid diffusion of gases across cell membranes

type 2 alveolar cells

• simple cuboidal cells

• synthesis of surfactant to reduce surface tension

alveolar macrophages

• mobile phagocytes

• clean up and digest debris that made its way into alveolus

Inspiration (inhalation)

brings air into lungs

Expiration (exhalation)

moves air out of lungs

Boyle’s law

pressure and volume are inversely proportionate

atomospheric pressure

• molecules of air

• pull of gravity on air around us creates atmospheric pressure

  • at sea level atmospheric pressure is about 760 mm Hg

intrapulmonary pressure

• air pressure within alveoli

  • equalizes with atmospheric pressure between breathes

intrapleural pressure

• pressure within alveoli

• does not equalize with atmospheric pressure

• normally about 4 mm Hg less than intrapulmonary pressure

• (pleural fluid is constantly pumped out of pleural cavity and into lymphatic vessels)

What happens if intrapleural pressure increases to a level at or above atmospheric pressure?

• lungs immediately collapse

• excess fluid (pleural effusion)

• air (pneumothorax)

• blood (hemothorax) in cavity 760 mm Hg

Average breath rate

12 breathes per minute

Inspiration what happens

diaphragm and external intercostal muscles contract

between inspiration and expiration

diaphragm and external intercostal muscles remain contracted to hold thorax at increased diameter and lungs at increased volume

expiration what happens

diaphragm and external intercostal muscles relax

not necessarily gas exchange

• sigh

• yawn

• sneeze

• cough

Physical factors influencing pulmonary ventilation

resistance

• diameter

• controlled by smooth muscle

• relaxation (bronchodilation)

• contraction (bronchoconstriction)

Surface tension

gas-water boundary

• where water molecules form hydrogen bonds

• gases are nonpolar

• water boundary greatest when alveoli are at their smallest diameter during expiration

surfactants (hydrophilic)

• opposes surface tension’s collapsing force

• has both polar and nonpolar end

• disrupts water’s ability to hydrogen bond with itself, reduces surface tension allows alvoelus

Compliance

• pulmonary compliance - ability of lungs and chest wall to stretch

• determined by three factors: degree of alveolar surface tension (surfactant counteracts this collapsing force, increases compliance), distensibility of elastic tissue (gives lungs ability to stretch during inflation increases compliance), ability of the chest wall to move (stretch during inspiration, increases compliance)

Lung volume total

6 liters

inhaling exhaling unconciously

500 ml (tidal volume) 2500 ml to 3000 ml

Vital capicity

air able to move in/out of lungs (around 5 liters same with blood)

how much air is left

1000 ml to 1200 ml (residual volume) due to surfactants

IRV is

how much air that is able to get in the lungs

Inspiratory capacity euqals

TV + IRV

Functional residual volume equals

ERV + RV

Vital capacity equals

TV + IRV + ERV

Total lung capacity equals

IRV + TV + ERV + RV

Minute Volume

• TV multiplied by number of breaths per minutes

  • 12 bpm

  • 6 L min

Anatomical dead space

• conduction zone

• 150 ml

alveolar ventilation rate

• volume of air that reaches alveoli

• minute volume - dead space = AVR