Intrapulmonary Pressure

1) lung volume

-In alveoli (palv)

-equals atmospheric pressure at 'rest'

-altered by changes in (1)

Intrapleural Pressure

1 = lungs and chest wall

-pressure in intrapleural space (Ppl)

-subatomic (negative) at rest

-determined by 1

Transpulmonary Pressure

1-lung volume

Pressure difference across lung (Palv - Ppl)

-determines 1

C = delta(V)/delta(P)

1= lung structure

2= surface tension

Compliance (C) = ?

-determined by 1 and 2

Law of Laplace: P= (2xT)/r

T= surface tension

r=radius

-Phospholipid mixture

-lowers surface tension

-more effective as alveolar radius decreases

-clinical relevance = (RDS and ARDS)

R = pressure/flow

airway diameter

Resistance (R) = ?

primarily determined by 1

-ease with which air flows through airways

-pressure required to achieve air flow

1) diaphragm contracts, increasing thoracic volune

2) Parasternal/external intercostals contract, plus accessory muscles, pulling rubs up and out

3) Intrapleural pressure becomes more negative

4) Lung "pulled" open, increasing lung volume

5) Alveolar pressure becomes subatomic

6) Air flows in

1) Inspiratory Muscles relax

2) Intrepleural pressure becomes less negative

3) Lung volume decreases

4) Intrapulmonary Pressure becomes positive

5) air flows out of lung

1) Internal intercostal and abdominal muscles contract

2) Expiratory pressure increased

3) Air flows faster, more variable

MV = F x Vt

F= frequency (breaths/min)

Vt = tidal volume (ml)

AV = F x (Vt-Vd)

F = frequency (breaths/min)

Vt = tidal volume (ml)

Vd = anatomic dead space

Alveolar Ventilation = ?

-strongly affects gas exchange

-slow, deep breathing vs. panthing

-scarring of lung structure

-ex. anthracosis

-alveolar tissue is destroyed

-reduces surface area for gas exchange

-small airways collapse limits expiration

-stimulated by cigarette smoking

1) temp of fluid

2) partial pressure of gas

3) solubility of gas

Henry's Law: Gas dissolved in liquid exerts a pressure

-In liquid equilibrated with a gas mixture, partial pressures are equal in the two phases

-The amount of gas dissolved in liquid is determined by: 1-3

alveolar PO2 decreases

-low vascular resistance

-low pressure system (10 mm Hg)

-fine-tunes medullary output

-integrates vagus nerve input

-automatic coordination

-motor tasks

-emotion

-conscious control

-separate spinal pathway

Central Chemoreceptors (Medulla)

1) automatic breathing

-detect changes in arterial PCO2 (regulated by 1)

-CO2 diffused across blood-brain barrier, forms H2CO3

-Neurons detect drop in CSF pH

-slow response (mins)

-rise in arterial PCO2

-rise in arterial [H+], fall in pH

-fall in arterial PO2

respond to bradykinin, histamine (injury)

produces rapid/shallow breathing (pain)

-located in airway mucosa

-respond to inhaled irritants

-stimulate cough (yawn)

-sense lung volume

-bronchodialtion, inhibit inspiration

-Hering-Breuer reflex

-Controls hemoglobin synthesis

-production regulated by kidney PO2

1) Binding cooperativity

2) O2 loading in lungs

3) Unloading in tissues

In oxyhemoglobin dissocation curve the following are due to..

1) S-shape

2) Upper plateau

3) steep slope

veins = 40 mm Hg

arteries = 100 mm Hg

-More O2 binding affinity

-pH rise, H+ drop

-PCO2 drop

-Temperature drop

-2,3-DPG drop

Left shift on oxyhemoglobin dissociation curve causes..

-Less O2 binding affinity

-pH drop/ H+ rise

-PCO2 rise

-temperature rise

-2,3-DPG rise

-2 y-chains in place of B-chains

-cannot bind 2,3 DPG

-higher affinity for O2

valine substitute for glutamic acid on position 6 of B chain

-crosslinks form "paracrystallin gel"

-RBCs less flexible, more fragile

-opposes malarial infection

1) 70%

2) 10%

3) 20 %

CO2 transport in blood (%)..

1) HCO3-

2) dissolved CO2

3) Carbaminohemoglobin