BIOL 1051H Lecture Notes - Lecture 1: Breathing, Intrapleural Pressure, Rib Cage

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3 May 2018

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Respiratory and Urinary Systems

Major functions of respiration

●Gas exchange

●Communication

●Olfaction: sense of smell

●Acid-Base balance

●Blood and lymph flow

Pulmonary Ventilation

●Consists of a repetitive cycle inspiration and expiration

●Flow of air in and out of lung depends on a pressure difference between air within

lungs and outside body

●Respiratory muscles change lung volumes and create difference in pressure relative to

the atmosphere that controls air flow

Intrapleural pressure causes lungs to expand with expansion of the thoracic cage

●Intrapleural pressure: negative pressure that exists between the two pleural layers

○The small space between the parietal and visceral pleura is filled with watery

fluid, and so these layers stay together

○Recoil of lung tissue and tissues of thoracic cage causes lungs and chest wall to be

pulling in opposite directions

During the process of expiration, the alveolar pressure is this;

●Greater than the barometric pressure

Resistance Decreased Airflow

●Resistance influenced by

○Diameter of the bronchioles

■Bronchodilation: increase in diameter of a bronchus or bronchiole =

increase airflow

○Pulmonary Compliance

■Ease with which the lungs can expand

■Decrease by lung diseases in which the lungs are stiffened by scar tissue

■Compliance is limited by the surface tension of the water in alveoli

Spirometry- The Measurement of Pulmonary Ventilation

●Spirometer

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○A device that recaptures expired breath and record such variables as rate and

depth of breathing, speed of expiration, and rate of oxygen consumption

●Spirometry

○The measurement of pulmonary function

○Aid in diagnosis and assessment of restrictive and obstructive lung disorders

Respiratory Volumes Measured By Spirometry

●Tidal Volume (TV)

○Volume of air inhaled and exhaled in one cycle of breathing (500mL)

●Inspiratory Reserve Volume (IRV)

○Air in excess of tidal volume that can be inhaled with maximum effort

●Expiratory Reserve Volume (ERV)

○Air in excess of tidal volume that can be exhaled with maximum effort

●Residual Volume (RV)

○Air remaining in lungs after maximum expiration

●Vital Capacity (VC) (ERV +TV + IRV)

○Total amount of air that can be inhaled after a normal tidal expiration

●Inspiratory Capacity (IC) (TV + IRV)

○Maximum amount of air that can be inhaled after a normal tidal expiration

●Functional Residual Capacity (FRC) ( RV + ERV)

○Amount of air remaining in lungs after a normal tidal expiration

●Total Lung Capacity (TLC) (RV + VC)

○Maximum amount of air that lungs can contain

Gas Exchange and Transport

●Dalton’s law- total atmospheric pressure is the sum of the contributions of the individual

gases

○Partial pressure: the separate contribution of each gas in a mixture

The partial pressure of oxygen is normally the greatest in this area

●Inspired air

Adjustment of the Metabolic Needs of Individual Tissues

●Factors that adjust the rate of oxygen unloading to match need;

○Ambient PO2

■Active tissues has PO2:02 is released from Hb

○Temperature

■Active tissue has temp; promotes o2 unloading

○Bohr Effect

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Document Summary

Consists of a repetitive cycle inspiration and expiration. Flow of air in and out of lung depends on a pressure difference between air within. Respiratory muscles change lung volumes and create difference in pressure relative to lungs and outside body the atmosphere that controls air flow. Intrapleural pressure causes lungs to expand with expansion of the thoracic cage. Intrapleural pressure: negative pressure that exists between the two pleural layers. The small space between the parietal and visceral pleura is filled with watery fluid, and so these layers stay together. Recoil of lung tissue and tissues of thoracic cage causes lungs and chest wall to be pulling in opposite directions. During the process of expiration, the alveolar pressure is this; Bronchodilation: increase in diameter of a bronchus or bronchiole = increase airflow. Ease with which the lungs can expand. Decrease by lung diseases in which the lungs are stiffened by scar tissue.

Related Questions

Case Study 1: Case Presentation

John, a healthy twenty-eight year old electrical engineer, was driving home from work one evening when he experienced sudden stabbing pain in his right pectoral and right lateral axillary regions. He began to feel out of breath and both his respiratory rate and heart rate increased dramatically. As luck would have it, John passed a hospital each day on his way home and was able to get himself to the hospitalâs emergency room. The emergency room physician listened to Johnâs breathing with a stethoscope and requested blood gas analysis and a chest x-ray. John answered a few of the doctorâs questions. The doctor noted that John had no history of respiratory problems but was a heavy smoker.

After viewing the chest radiograph, the doctor informed John that he had experienced a spontaneous pneumothorax, or what is commonly called a collapsed lung. The doctor explained that a hole had opened in Johnâs right lung and that this hole had allowed air to leak into the cavity surrounding the lung. Then, as a result of the lungâs own elastic nature, the lung had collapsed. The doctor said he could not be certain of the cause of the pneumothorax, but smoking cigarettes had certainly increased the likelihood of it happening. He told John he was fortunate the pneumothorax was small, which meant that relatively little air had escaped from the lung into the surrounding cavity, and it should heal on its own. He instructed John to quit smoking, avoid high altitudes, flying in nonpressurized aircraft, and scuba diving. He also had John make an appointment for a re-check and another chest x-ray.

Case Background

Spontaneous pneumothorax occurs when a blister on the surface of the lung opens, allowing air from the lung to move into the pleural cavity. This occurs because alveolar pressure is normally greater than the pressure in the pleural cavity. As air escapes from the lung, the lung tissues will recoil, and the lung will begin to collapse. The lung will continue to collapse until the difference between the alveolar pressure and pleural pressure disappears or until the collapsing of the lung causes the opening to seal.

The pneumothorax decreases the efficiency of the respiratory system, which in turn results in decreased blood oxygen concentration, increased respiratory rate, and increased heart rate. If the pneumothorax is small, the air that escapes into the pleural cavity can be reabsorbed into the lung once the opening has sealed shut. If the pneumothorax is large, a needle or chest tube may have to be inserted into the pleural cavity to draw the air out and allow for the reexpansion of the lung.

Questions

Define the following terms and explain how they may have been affected by Johnâs spontaneous pneumothorax.

Visceral pleura

Parietal pleura

Pleural cavity

As a result of a pneumothorax, the lung tissues recoil, and the lung collapses. Explain how recoil and collapse are prevented in a healthy lung?

How does elastic recoil function in breathing?

Why was John instructed to avoid high altitudes and flying in nonpressurized aircraft?

Case Study 2: The Case of the Coughing Housewife

Jessica, a fifty-nine year old mother of four, moved from a ranch in Colorado to Los Angeles, after the death of her husband, to be closer to her oldest son and his family. She has been in Los Angeles for 18 months and has noticed that she is experiencing shortness of breath which has worsened over the last six months. For the last week, she has been coughing and bringing up yellow mucus. She also noticed swelling in her ankles so she decided to visit a physician about her condition.

Jessica's family and medical history include a negative history of asthma or allergies, lack of occupational or home exposure to asbestos, a previous smoking history (one package of cigarettes per day between the ages of 16 and 52), episodes of bronchitis, treated with antibiotics on an outpatient basis, and a positive history of heart disease (father at 52 and brother at 56). Jessica has no history of serious illness, including heart disease, and her weight is within five pounds of her "desired" weight. She usually coughs in the morning to "clear her throat", but there is usually only a small amount of white mucus.

Her nurse practitioner conducts a general physical examination with the following results. Jessica's skin is normal (no rashes or cyanosis) and her nervous system is functioning normally. Her body temperature was 98.4oF while her pulse was regular at 95 beats per minute with an occasional premature beat. Jessica's blood pressure was within normal limits, however her jugular veins were slightly distended. Her respiratory rate was 28 breaths per minute; she breathed with pursed lips and used her accessory respiratory muscles more than would be expected. Jessica presented with a barrel chest and mild dyspnea when climbing onto the examination table. When listening to her breathing, the nurse practitioner noticed that Jessica had prolonged expiration accompanied by expiratory wheezes. Evaluation of her abdomen indicated no masses or tenderness, but she presented with both hepatomegaly and splenomegaly. All of her extremities were normal with the exception of bilaterally pedal edema.

Based on these results, the nurse practitioner suspected a pulmonary disorder and, after consultation with a physician, ordered laboratory tests (blood and sputum), spirometry and chest x-rays. The results of the laboratory tests were as follows: plasma bicarbonate = 38 mEq/L, hematocrit = 49%, white blood cell count = 9000, pH = 7.38; PaCO2 = 56, and PaO2 = 54. Analysis of the sputum sample indicated the presence of epithelial cells, polymorphonucleocytes and gram positive diplococci. Jessica's 1 second forced expiratory volume (FEV1) was 1.5 L/sec and her forced vital capacity (FVC) was 4 L. These values were 40% and 83% of normal, respectively. Results of the chest x-ray indicated scarring and hyperinflation of the lungs.

The results of these tests coupled with the physical examination and history lead to a diagnosis of emphysema. Jessica was prescribed antibiotics for the infection and oxygen by nose as well as a b2-agonist nebulizer as an acute treatment and requested to stay for observation and stabilization. After Jessica's condition was stabilized she was discharged and given a prescription for an inhaler containing a b2-agonist to be used as needed. She was also encouraged to exercise regularly and follow the nutritional guidelines she was given. Jessica was also informed that if the symptoms either worsened or did not lessen within the next week, to return and her treatment would be reevaluated and would possibly include nocturnal oxygen and an inhaler containing corticosteroids.

Answer the following questions about this case

Define the bold terms in the text. (8 points)

What risk factors and symptoms did Jessica present with prior to the physical examination that suggested a pulmonary disorder?

How did the physical examination, chest X-ray and spirometry confirm this hypothesis?

Identify muscles involved in respiration and how these muscles are responsible for the process of ventilation.

How will the b2-agonist in the inhaler help with the respiratory problems Jessica presents with?

Why is it important that a b2-agonist and not simply an b-agonist is used in the inhaler?

If her condition does not progress, why would corticosteroids be used in the inhaler?

BIOL 1051H Lecture Notes - Lecture 1: Breathing, Intrapleural Pressure, Rib Cage

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