Why is epinephrine injected as a treatment for the respiratory signs and symptoms of anaphylaxis?
Epinephrine enhances sympathetic activity to dilate airways and decrease airway resistance, which had been elevated by the effects of histamine on the bronchioles. It also raises blood pressure, which enhances oxygen delivery to tissues by increasing flow.
Describe and explain the effects of smoking on the functioning of the respiratory system.
Nicotine constricts terminal bronchioles to increase airway resistance, as does the increased mucus secretion and swelling of the mucosa. Smoke inhibits the movement of cilia, which allows buildup of substances and microbes normally removed. Over time, smoking leads to destruction of elastic tissue, which decreases compliance, and ultimately to the effects of emphysema.
Describe the neural, chemical, and physical changes that increase the rate and depth of ventilation during exercise.
Anticipation of exercise generates neural input to the limbic system. Sensory input is provided from proprioceptors and motor input is provided from the primary motor cortex. As the partial pressure of oxygen falls due to increased consumption, the partial pressure of carbon dioxide and the temperature increase due to metabolic activity in muscle fibers. Also, carbon dioxide is added via the buffering of the hydrogen ions produced as a result of lactic acid production. Chemoreceptors sense the changes in partial pressure and notify the medullary rhythmicity center to increase the rate and depth of breathing.
In chronic emphysema, some alveoli merge together and some are replaced with fibrous connective tissue. In addition, the bronchioles are often inflamed, and expiratory volume is reduced. Using proper respiratory system terminology, explain at least four reasons why affected individuals will have problems with ventilation and external respiration.
Answers could include: reduced compliance (reduces ability to increase thoracic volume); increased airway resistance (decreases tidal volume); decreased diffusion due to increased diffusion distance, decreased surface area, and changes in partial pressures of gases (altering gradients). Other answers may be acceptable.
The upper respiratory system includes
the nose, nasal cavity, pharynx, and associated structures
the lower respiratory system includes
the larynx, trachea, bronchi, and lungs.
As air passes through the nose
it is warmed, filtered, and moistened; and olfaction occurs.
The external nose has a
cartilaginous framework and a bony framework
The glottis consists of
a pair of folds of mucous membrane in the larynx (the vocal folds) and the space between them (the rima glottidis).
The bronchial tree consists of
macroscopic airways that begin at the trachea and continue through the terminal bronchioles.
The parietal pleura lines the
the thoracic cavity, and the visceral pleura covers the lungs
The oblique fissure
divides the left lung into two lobes.
The oblique and horizontal fissures
divide the right lung into three lobes.
Alveolar sacs consist of
of two or more alveoli that share a common opening.
The exchange of respiratory gases occurs by
diffusion across the respiratory membrane.
The volume of a gas varies
inversely with its pressure
During normal, quiet inhalation,
the diaphragm and external intercostals contract, the lungs expand, and air moves into the lungs; during normal, quiet exhalation, the diaphragm and external intercostals relax and the lungs recoil, forcing air out of the lungs.
Air moves into the lungs when
alveolar pressure is less than atmospheric pressure, and out of the lungs when alveolar pressure is greater than atmospheric pressure.
Lung capacities are
combinations of various lung volumes.
Gases diffuse from
areas of higher partial pressure to areas of lower partial pressure.
Most O2 is transported by
hemoglobin as oxyhemoglobin (Hb–O2) within red blood cells
most CO2 is transported in
blood plasma as bicarbonate ions (HCO3_).
As PO2 increases,
more O2 combines with hemoglobin.
As temperature increases
the affinity of hemoglobin for O2 decreases
Fetal hemoglobin has a higher
affinity for O2 than does adult hemoglobin.
The respiratory center is composed of
neurons in the medullary respiratory center in the medulla plus the pontine respiratory group in the pons.
During normal quiet breathing
the ventral respiratory group is inactive
during forceful breathing
the dorsal respiratory group activates the ventral respiratory group.
Which structures are part of the conducting zone of the respiratory system?
The conducting zone of the respiratory system includes the nose, pharynx, larynx, trachea, bronchi, and bronchioles (except the respiratory bronchioles).
What is the path taken by air molecules into and through the nose?
The path of air is
external nares --> vestibule --> nasal cavity internal nares.
Which part of the nose is attached to the frontal bone?
The root of the nose attaches it to the frontal bone.
How does the epiglottis prevent aspiration of foods and liquids?
During swallowing, the epiglottis closes over the rima glottidis, the entrance to the trachea, to prevent aspiration of food and liquids into the lungs.
What is the main function of the vocal folds?
The main function of the vocal folds is voice production.
What is the benefit of not having complete rings of tracheal cartilage between the trachea and the esophagus?
Because the tissues between the esophagus and trachea are soft, the esophagus can bulge and press against the trachea during swallowing.
How many lobes and secondary bronchi are present in each lung?
The left lung has two lobes and two lobar bronchi; the right lung has three of each.
What type of membrane is the pleural membrane?
The pleural membrane is a serous membrane.
Why are the right and left lungs slightly different in size and shape?
Because two-thirds of the heart lies to the left of the midline, the left lung contains a cardiac notch to accommodate the presence of the heart.
The right lung is shorter than the left because the diaphragm is higher on the right side to accommodate the liver.
What types of cells make up the wall of an alveolus?
The wall of an alveolus is made up of type I alveolar cells, type II alveolar cells, and associated alveolar macrophages.
How thick is the respiratory membrane?
The respiratory membrane averages 0.5 _m in thickness.
If the volume is decreased from 1 liter to 1/4 liter, how would the pressure change?
The pressure would increase fourfold, to 4 atm.
Right now, what is the main muscle that is powering your breathing?
If you are at rest while reading, your diaphragm is responsible for about 75% of each inhalation.
How does the intrapleural pressure change during a normal, quiet breath?
At the start of inhalation, intrapleural pressure is about 756 mmHg. With contraction of the diaphragm, it decreases to about 754 mmHg as the volume of the space between the two pleural layers expands. With relaxation of the diaphragm, it increases back to 756 mmHg.
If you breathe in as deeply as possible and then exhale as much air as you can, which lung capacity have you demonstrated?
Breathing in and then exhaling as much air as possible demonstrates vital capacity
What causes oxygen to enter pulmonary capillaries from alveoli and to enter tissue cells from systemic capillaries?
A difference in PO2 promotes oxygen diffusion into pulmonary capillaries from alveoli and into tissue cells from systemic capillaries.
What is the most important factor that determines how much O2 binds to hemoglobin?
The most important factor that determines how much O2 binds to hemoglobin is the PO2.
What point on the curve represents blood in your pulmonary veins right now? In your pulmonary veins if you were jogging?
Both during exercise and at rest, hemoglobin in your pulmonary veins would be fully saturated with O2, a point that is at the upper right of the curve.
In comparison to the value when you are sitting, is the affinity of your hemoglobin for O2 higher or lower when you are exercising? How does this benefit you?
Because lactic acid (lactate) and CO2 are produced by active skeletal muscles, blood pH decreases slightly and PCO2 increases when you are actively exercising. The result is lowered affinity of hemoglobin for O2, so more O2 is available to the working muscles.
Is O2 more available or less available to tissue cells when you have a fever? Why?
O2 is more available to your tissue cells when you have a fever because the affinity of hemoglobin for O2 decreases with increasing temperature.
The PO2 of placental blood is about 40 mmHg. What are the O2 saturations of maternal and fetal hemoglobin at this PO2?
At a PO2 of 40 mmHg, fetal Hb is 80% saturated with O2 and maternal Hb is about 75% saturated.
Would you expect the concentration of HCO3 _ to be higher in blood plasma taken from a systemic artery or a systemic vein?
Blood in a systemic vein would have a higher concentration of HCO3_.
Which area contains neurons that are active and then inactive in a repeating cycle?
The medullary respiratory center in the medulla contains neurons that are active and then inactive in a repeating cycle.
Which nerves convey impulses from the respiratory center to the diaphragm?
The phrenic nerves innervate the diaphragm.
Which chemicals stimulate peripheral chemoreceptors?
Peripheral chemoreceptors are responsive to changes in blood levels of oxygen, carbon dioxide, and H_.
What is the normal arterial blood PCO2?
Normal arterial blood PCO2 is 40 mmHg.
When does the respiratory system begin to develop in an embryo?
The respiratory system begins to develop about 4 weeks after fertilization.