Respiratory Physiology

Reference: Guyton 14th; P- 515

Ganong 26 : 645-646

Davidson 24th

Definite cyanosis appears whenever the arterial blood contains more than 5 grams of deoxygenated hemoglobin in each 100 ml of blood. A person with anemia almost never becomes cyanotic. Conversely, in a person with Polycythemia vera frequently has cyanosis, even under otherwise normal conditions.

Alveolar macrophages or dust cells are principal mononuclear phagocytes of the alveolar surface. It removes inhaled dust, bacteria and other particulate matter trapped in the pulmonary surfactant, thus providing a vital line of defense in the lungs.

The medium-sized bronchi actually constitute the site of highest resistance along the bronchial tree. Although the small radii of the alveoli might predict that they would have the highest resistance, they do not because of their parallel arrangement. In fact, early changes in resistance in the small airways may be “silent” and go undetected because of their small overall contribution to resistance.

Reference: Guyton 14th; P- 492

Respiratory gases pass through the alveolar capillary membrane by passive diffusion.

Zones 1, 2, and 3 of Pulmonary Blood Flow
The capillaries in the alveolar walls are distended by the blood pressure inside them but simultaneously are compressed by the alveolar air pressure on their outsides. Therefore, whenever the lung alveolar air pressure becomes greater than the capillary blood pressure, the capillaries close, and there is no blood flow.
Under different normal and pathological lung conditions, one may find any one of three possible zones (patterns) of pulmonary blood flow, as follows:

Zone 1: No blood flow during all portions of the cardiac cycle because the local alveolar capillary pressure in that area of the lung never rises higher than the alveolar air pressure during any part of the cardiac cycle
Zone 2: Intermittent blood flow only during the peaks of pulmonary arterial pressure because the systolic pressure is then greater than the alveolar air pressure, but the diastolic pressure is less than the alveolar air pressure
Zone 3: Continuous blood flow because the alveolar capillary pressure are remains greater than alveolar air pressure during the entire cardiac cycle

Normally, the lungs have only zones 2 and 3 blood flow-zone 2 (intermittent flow) in the apices and zone 3 (continuous flow) in all the lower areas.

কোন ব্যাখ্যা যোগ হয় নি।

Volume, which cannot be measured by spirometry, is the residual volume. Capacities, which include residual volume also cannot be measured. Capacities that include residual volume are functional residual capacity and total lung capacity.

[Ganong 24th p-638]

Ganong 26 th p 619-620

Reference: Guyton 14th; P- 496

কোন ব্যাখ্যা যোগ হয় নি।

কোন ব্যাখ্যা যোগ হয় নি।

কোন ব্যাখ্যা যোগ হয় নি।

Davidson 24th

[Ganong 24th p-659]

Elastic work 65%

Ganong 26,Page 620

The ultimate goal of respiration is to maintain proper concentrations of O2, CO2 & H+

[Ganong 24th p-643]

Reference: Guyton 14th; P- 491

Energy Required for Respiration.
During normal quiet respiration, only 3% to 5% of the total energy expended by the body is required for pulmonary ventilation. However, during heavy exercise, the amount of energy required can increase as much as 50-fold, especially if the person has any degree of increased airway resistance or decreased pulmo- nary compliance. Therefore, one of the major limitations on the intensity of exercise that can be performed is the person's ability to provide enough muscle energy for the respiratory process alone.

Volume, which cannot be measured by spirometry, is the residual volume. Capacities, which include residual volume also cannot be measured. Capacities that include residual volume are functional residual capacity and total lung capacity.

Guyton  13th-501-502

Reference: Guyton 14th; P- 495

Reference: Guyton 14th; P- 533

Reference: Guyton 14th; P- 526

Reference: Guyton 14th; P- 528

Dr Abdullah Short Case

Volume, which cannot be measured by spirometry, is the residual volume. Capacities, which include residual volume also cannot be measured. Capacities that include residual volume are functional residual capacity and total lung capacity.

During normal breathing, the volume inspired and then expired is a tidal volume (TV). The volume remaining in the lungs after expiration of a TV is the functional residual capacity (FRC).

Explanation:
Definite cyanosis appears whenever the arterial blood contains more than 5 grams of deoxygenated hemoglobin in each 100 ml of blood. A person with anemia almost never becomes cyanotic. Conversely, in a person with Polycythaemia vera frequently has cyanosis, even under otherwise normal conditions.

Reference: Guyton 14th; P- 498

Contraction of the smooth muscle that lines the bronchial airways will increase airway resistance and make breathing more difficult.

Guyton 13 th page 522

Explanation:

Reference: Guyton 14th; P- 492

Va/Q is infinity : No perfusion but ventilation remains normal.
Causes:
1. Embolism
2. Emphysema
3.Bronchiectasis

Ganong 26th Page 624
 

কোন ব্যাখ্যা যোগ হয় নি।

Definite cyanosis appears whenever the arterial blood contains more than 5 grams of deoxygenated hemoglobin in each 100 ml of blood. A person with anemia almost never becomes cyanotic. Conversely, in a person with Polycythemia vera frequently has cyanosis, even under otherwise normal conditions.

Explanation:
Internal intercostal muscle is primary expiratory muscle

Reference: Guyton 14th; P- 513

Uncal Herniation
Space-occupying lesions from large tumors, hemorrhages, strokes, or abscesses in the cerebral hemisphere can drive the uncus of the temporal lobe over the edge of the cerebellar tentorium, compressing the ipsilateral cranial nerve III (uncal herniation).
Before the herniation these patients experience a decreased level of consciousness, lethargy, poorly reactive pupils, deviation of the eye to a "down and out" position, hyperactive reflexes, and a bilateral Babinski sign (due to compression of the ipsilateral corticospinal tract).
After the brain herniates, the patients are decerebrate and comatose, have fixed and dilated pupils, and eye movements are absent. Once damage extends to the midbrain, a Cheyne-Stokes respiratory pattern develops.

Explanation:

Reference: Guyton 14th; P- 496

Volitional tests of respiratory include
a- Mouth Pressures (Maximal Static Inspiratory and Expirato Pressure).
b- Sniff Test
c- SNIP Test (Sniff pressure at nose measured )
d- Cough Tests

Movement of the diaphragm accounts for 75% of the change in intrathoracic volume during quiet inspiration. Attached around the bottom of the thoracic cage, this muscle arches over the liver and moves downward like a piston when it contracts. The distance it moves ranges from 1.5 cm to as much as 7 cm with deep inspiration.