Human Respiration Questions 1. What is the definition of a respiratory capacity?
ID: 3516005 • Letter: H
Question
Human Respiration Questions 1. What is the definition of a respiratory capacity? 2. The vital capacity is compromised by what pathologies? 3. Chemoreceptors in the brain respond to changes in the pH of the cerebrospinal fluid, but the blood-brain barrier blocks the passage of most ions, including H+ into the cerebrospinal fluid. What, then, causes the changes in pH to which the cerebral chemoreceptors respond? 4. Where are the peripheral chemoreceptors located? What stimulates them? 5. During the exercise portion of the lab, which volumes changed the most and why? 6. What is apnea and when might it occur? What complications are associated with apnea?Explanation / Answer
1. Respiratory capacity also called as Vital capacity which is the maximum volume of air that can be inhaled (after maximum inhalation) or exhaled (after maximum expiration).
Respiratory capacity = Tidal volume + Inspiratory reserve volume + Expiratory Reserve volume.
Respiratory capacity is 80% of total lung capacity (total lung capacity= 6000mL). So
the respiratory capacity normal value is 4800 mL which may vary according to age and body size
Tidal volume is defined as the amount of aiar inspired during normal breathing (Tidal volume =500mL)
Inspiratory Reserve Volume (IRV) is the additonal amount of air that can be forcible inhaled after inspiration of a normal tidal volume. Normal IRV = 3100mL
Expiratory Reserve Volume is the additional amount of air that can be forcibly exhaled after the expiration of a normal tidal volume which is about 1200mL
Residual volume is the volume of air still remaining in the lungs after the expiratory reserve volume is exhaled. The normal residual volume is 1200 mL
Answer for 2:
2. The vital capacity is compromised by pathologies like :
Reduction in Vital capacity: Restrictive lung diseases like fibrosing alveolitis, neuromuscular diseases like myasthenia gravis, severe Guillain Barre syndrome, phrenic nerve palsy
Elevation in Vital capacity: Bronchial asthma, Chronic obstructive pulmonary disorder increases the vital capacity values
Hence, Spirometer is used to measure the respiratory capacity which serves as a diagnostic tool for the above disesases
Answer 3:
(Chemoreceptors in the brain are located on the ventrolateral medullary surface near the exit of the 9th and 10th cranial nerves. These are also called as medullary neurons)
Chemoreceptors in the brain are different from peripheral receptors as these do not detect change in pH with respect to H+ ions (as they are impermeable to the Blood brain barrier). Instead, Chemoreceptors present in the brain recognise the decrease in pH due to carbonic acid production. This carbonic acid is produced by increased CO2 levels which can access the blood brain barrier unlike protons. The CO2 then reacts with water to form carbonic acid which serves as a stimulus for central chemoreceptors.
CO2 + H2O <-------------> H2CO3 -----> Results in reduction of pH which is sensed by chemoreceptors
4. Answer:
Peripheral chemoreceptors are located in the carotid and aortic bodies
These are stimulated by decrease in blood oxygen tension and pH (change in H+concentration). A reduction in arterial blood Oxygen tension stimulates the peripheral chemoreceptors
5. Answer: Increased ventilation occurs during exercise to meet the increased oxygen demand from muscles
Tidal volume, Inspiratory capacity increases during exercise.
Inspiratory reserve volume and Expiratory reserve volume decrease during exercise
The residual volume remains the same
There is a slight decrease in Vital capacity, Total Lung capacity during exercise.
6. Answer:
Abnormal periodic cessation of breathing is called as apnea. (It lasts atleast for 10 seconds).
When does Apnea occur?
Apnea may be drug induced (Opioids, tyrptamine etc), mechanically induced (strangulation or choking), or occurs as a result of neurological disease or trauma.
Complications: Prolonged apnea leads to permanent irreversible Brain damage, sleep apnea has complications like daytime fatigue, hypertension, Type 2 diabetes, liver dysfunction, insomnia etc
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