ACID BASE BALANCE

Ventilation

The bulk movement of air into and out of the lungs. It is responsible for the exchange of oxygen and carbon dioxide between the alveoli and pulmonary capillary blood.

Mouth pressure

Pressure at the entry of the respiratory system

Alveolar Pressure

Pressure within the alveoli

Esophageal Pressure

Pressure at the level of the midesophagus

Body surface pressure

v Atmospheric pressure

v Pressure sa gawas sa lawas

v Pressure needed to overcome to bring air inside the lungs

Abdominal pressure

Pressure measured in the abdominal cavity

Transpulmonary pressure Ptp

is the difference between Palv(alveolar) and pleural pressure (Ppl). Pressure difference across the lung

Transthoracic pressure Ptt

is the difference between Palv(alveolar) and body surface pressure (Pbs), Pressure differences across the thorax, including chest and diaphragm

Transrespiratory pressure Pta

Pressure difference across the lung-thorax system,

Transdiaphragmatic pressure

Pressure difference across the diaphragm

Barometric Pressure Pb

is the atmospheric pressure at the mouth

760 mmHg at sea level

Normal barometric Pressure

Static

refers to matter at rest and to forces in equilibrium.

Lungs’ elastic properties, Surface tension of the alveolar fluid lining

Driving forces of the static compliance in the lungs

Compliance

the volume (in litres, L) change per unit of pressure (cm H2O) change.

0.1 L/cm H2O

Normal lung compliance

Elastance

is the lung’s attempting to return to its original size and shape when force (pressure) is not being applied.

Surface Tension

is the molecular, cohesive force at the liquid-gas interface in the alveoli, which, if left unchecked, would cause the alveoli to collapse.

LaPlace’s Law

What law states that The distending pressure of a liquid sphere (alveoli) is directly proportional to the liquid’s surface tension and inversely proportional to the sphere’s radius. Distending pressure varies inversely with the radius of the alveoli

Critical Opening Pressure

 is the high pressure needed to initially open a bubble by overcoming its cohesive force, such as blowing up a balloon.

Critical Closing Pressure

is the point at which the liquid cohesive forces exceed the distending pressure and the sphere collapses

Pulmonary Surfactant

Functions to decrease alveolar surface tension in proportion to the ratio of surfactant to alveolar surface area.

dipalmitoyl phosphatidyl choline

major component of surfactant

Alveolar Type 2 cells

dipalmitoyl phosphatidyl choline is produced by what

Dynamic

refers to the movement of gas into and out of the lungs and to the related pressure changes.

 

Dynamic Compliance

It is the change in lung volume divided by the change in transpulmonary pressure as measured by esophageal balloon. is measured during gas flow and includes Raw, whereas static compliance is measured without gas flow.

Poiseuille’s law

Describes the relationship between gas flow and pressure through non-rigid airways

Airway Resistance

Pressure difference between the mouth and the alveoli (transairway), divided by the flow rate (L/s

0.5–2.5 cm H2O/L/s

What is the normal Raw

Laminar

streamlined and smooth, found with low flow rates and low pressure differences

Turbulent

random and rough, found with high flows and high pressure differences

Transitional

A mixed condition of turbulent and laminar, found near airway branching

Time constants

It is the time necessary to inflate an alveolus to 60% of its potential filling capacity and is a product of Raw and CL

60%

What is the percentage necessary to inflate an alveolus to reach a time constant

Tidal Volume

is the volume of air inspired and expired in one normal breath

3–4 mL/lb

Ideal tidal volume value

Minute Ventilation

is the total volume of gas exhaled (or inhaled) per minute and is computed as (VT)(f)

6.0 L

Normal Minute Ventilation for an adult

Alveolar Ventilation

is the volume of inspired gas that reaches the alveoli and that is available for gas exchange with pulmonary capillary blood

Dead Space

 is the volume of gas in the lungs that does not participate in gas exchange.

Anatomic dead space

is the volume of gas in the conducting airways and normally equals 1 mL/lb of ideal body weight

Alveolar dead space

dead space that occurs when an alveolus is ventilated but not perfused with pulmonary capillary blood and therefore is not involved in gas exchange

Physiologic dead space

is the total dead space and is the sum of anatomic plus alveolar dead space.

200 mL

At rest an adult produces how much ml of carbon dioxide per minute?

250 mL

at rest an adult consumes how much ml of oxygen per minute

Hamburger Phenomenon

To maintain intracellular electrical neutrality, is replaced by chloride (Cl).

Carbonic anhydrase

RBC is converted to bicarbonate via hydrolysis and the reaction is speeded up by what enzyme?

hydrolysis

RBCs is converted to bicarbonate via what?

Acid-base balance

 refers to physiologic mechanism that keep hydrogen of body fluids in a range compatible with life

Volatile Acid

is one that is in equilibrium with a dissolved gas

carbonic acid

The only volatile acid of physiologic significance in the body is

isohydric buffering

v most H+ produced in this fashion causes no change in pH because hemoglobin (Hb) in the erythrocyte immediately buffers the H+. When blood reaches the lungs, Hb releases H+ to form CO2

Nonvolatile Acid

v In contrast to carbonic acid, these nonvolatile acids are not in equilibrium with a gaseous component

Bicarbonate System

v  an open buffer system because H2CO3 is in equilibrium with dissolved CO2 , which is readily removed by ventilation

H2CO3 AND HCO3

The bicarbonate buffer system consists of

Nonbicarbonate System

called a closed buffer system because all the components of acid-base reactions remain in the system. When H+ is buffered by Buf−, the product, HBuf, accumulates and eventually reaches equilibrium with the reactants, preventing further buffering activity

Phosphates and proteins, including Hb

The nonbicarbonate buffer system consists mainly of

Henderson-Hasselbalch Equation

specific for calculating the pH of the blood‘s bicarbonate buffer system