Respiratory system

adaptations of horse to exercise

• large airways

• huge lung capacity

• large volume of blood through lungs

• nose breather

• elongated respiratory system

respiratory anatomy

nasopharynx—>trachea—>bronchioles—>respiratory bronchiole—>alveoli

airway resistance

reduced when airway is larger

what is airway resistance proportional to?

1/radius of airway to power of 4

what characteristic of the airway causes changes to air resistance?

changes in the radius of the airway

how do bronchioles help reduce airway resistance?

by dilating or constricting

brocnchodilation

• bronchioles widen

• resistance decreases

bronchoconstriction

• airways constrict

• resistance increases

false nostril

catches air and directs it into lungs

soft palate

directs air into trachea

how does the kink in the trachea affect airway resistance?

causes airway resistance

what motion can horse do to straighten ink in trachea out and reduce air resistance?

put head down while exercising

thoracic cavity

• where force for moving air (breathing) is generated

• changing volume in cavity changes pressure in lungs (inverse relationship)

conduction zone

where air is moved/conducted

what makes up the conductive zone?

pulmonary airways

conduction zone

• conduct air

• clean air

• humidify air

• warm air

• adapts

does gas exchange occur in conductive zone?

no

respiratory exchange zone

• part of lungs where gas exchange between air and blood occurs

• O2 goes from lungs to blood

• CO2 moves from blood to air

what makes up the respiratory exchange zone?

• respiratory bronchioles

• alveolar ducts

• alveoli

concentration of O2 and CO2 in venous blood

• low in O2

• high in CO2

concentration of O2 and CO2 in alveolar blood

• high O2

• low CO2

flow rate

atmospheric pressure-alveolar pressure/airway resistance

how does airway resistance affect flow rate?

minimizing airway resistance optimizes flow rate

tidal volume

volume of air inspired and expired during one normal breath (~5-6L)

minute ventilation

how much air moves in and out of body per minute (L/min)

dead space

volume of air in conduction zone that does not participate in gas exchange

how can dead space be increased?

by dilating bronchioles

ficks law

• use large concentration gradient to optimize diffusion

• do over short distance

• do across thin and enormous SA

factors that affect rate of gas exchange

• partial pressure gradients of O2 and CO2

• surface area of alveolar membrane

• thickness of capillary-alveolar membrane

• ventilation-perfusion mismatch

ventilation-perfusion

measure of areas of lung that receive fresh air and blood

when does V/P mismatch occur

• areas of ventilation but no perfusion

• no ventilation but perfusion

pulmonary circulation

• stores blood for horse

• low capillary pressure

• low blood flow

• low resistance