Physiology

ala

(plural = alae) small, flaring structure of a nostril that forms the lateral side of the nares

naris

(plural = nares) opening of the nostrils

laryngopharynx

-portion of the pharynx bordered by the oropharynx superiorly and esophagus and trachea inferiorly; serves as a route for both air and food -part of the pharynx that functions in respiration and digestion

pharynx

-region of the conducting zone that forms a tube of skeletal muscle lined with respiratory epithelium; located between the nasal conchae and the esophagus and trachea -throat

root

-region of the external nose between the eyebrows

What is the major mechanism that results in acclimatization?

A major mechanism involved in acclimatization is the increased production of erythrocytes. A drop in tissue levels of oxygen stimulates the kidneys to produce the hormone erythropoietin, which signals the bone marrow to produce erythrocytes. As a result, individuals exposed to a high altitude for long periods of time have a greater number of circulating erythrocytes than do individuals at lower altitudes

During what timeframe does a fetus have enough mature structures to breathe on its own if born prematurely? Describe the other structures that develop during this phase.

At about week 28, enough alveolar precursors have matured so that a baby born prematurely at this time can usually breathe on its own. Other structures that develop about this time are pulmonary capillaries, expanding to create a large surface area for gas exchange. Alveolar ducts and alveolar precursors have also developed.

Compare and contrast Dalton's law and Henry's law.

Both Dalton's and Henry's laws describe the behavior of gases. Dalton's law states that any gas in a mixture of gases exerts force as if it were not in a mixture. Henry's law states that gas molecules dissolve in a liquid proportional to their partial pressure.

Compare and contrast adult hemoglobin and fetal hemoglobin.

Both adult and fetal hemoglobin transport oxygen via iron molecules. However, fetal hemoglobin has about a 20-fold greater affinity for oxygen than does adult hemoglobin. This is due to a difference in structure; fetal hemoglobin has two subunits that have a slightly different structure than the subunits of adult hemoglobin.

Describe three ways in which carbon dioxide can be transported.

Carbon dioxide can be transported by three mechanisms: dissolved in plasma, as bicarbonate, or as carbaminohemoglobin. Dissolved in plasma, carbon dioxide molecules simply diffuse into the blood from the tissues. Bicarbonate is created by a chemical reaction that occurs mostly in erythrocytes, joining carbon dioxide and water by carbonic anhydrase, producing carbonic acid, which breaks down into bicarbonate and hydrogen ions. Carbaminohemoglobin is the bound form of hemoglobin and carbon dioxide.

Describe fetal breathing movements and their purpose.

Fetal breathing movements occur due to the contraction of respiratory muscles, causing the fetus to inhale and exhale amniotic fluid. It is thought that these movements are a way to "practice" breathing, which results in toning the muscles in preparation for breathing after birth. In addition, fetal breathing movements may help alveoli to form and mature.

Describe what is meant by the term "lung compliance."

Lung compliance refers to the ability of lung tissue to stretch under pressure, which is determined in part by the surface tension of the alveoli and the ability of the connective tissue to stretch. Lung compliance plays a role in determining how much the lungs can change in volume, which in turn helps to determine pressure and air movement.

Outline the steps involved in quiet breathing

Quiet breathing occurs at rest and without active thought. During quiet breathing, the diaphragm and external intercostal muscles work at different extents, depending on the situation. For inspiration, the diaphragm contracts, causing the diaphragm to flatten and drop towards the abdominal cavity, helping to expand the thoracic cavity. The external intercostal muscles contract as well, causing the rib cage to expand, and the rib cage and sternum to move outward, also expanding the thoracic cavity. Expansion of the thoracic cavity also causes the lungs to expand, due to the adhesiveness of the pleural fluid. As a result, the pressure within the lungs drops below that of the atmosphere, causing air to rush into the lungs. In contrast, expiration is a passive process. As the diaphragm and intercostal muscles relax, the lungs and thoracic tissues recoil, and the volume of the lungs decreases. This causes the pressure within the lungs to increase above that of the atmosphere, causing air to leave the lungs.

What is respiratory rate and how is it controlled?

Respiratory rate is defined as the number of breaths taken per minute. Respiratory rate is controlled by the respiratory center, located in the medulla oblongata. Conscious thought can alter the normal respiratory rate through control by skeletal muscle, although one cannot consciously stop the rate altogether. A typical resting respiratory rate is about 14 breaths per minute.

Compare and contrast the conducting and respiratory zones.

The conducting zone of the respiratory system includes the organs and structures that are not directly involved in gas exchange, but perform other duties such as providing a passageway for air, trapping and removing debris and pathogens, and warming and humidifying incoming air. Such structures include the nasal cavity, pharynx, larynx, trachea, and most of the bronchial tree. The respiratory zone includes all the organs and structures that are directly involved in gas exchange, including the respiratory bronchioles, alveolar ducts, and alveoli.

A smoker develops damage to several alveoli that then can no longer function. How does this affect gas exchange?

The damaged alveoli will have insufficient ventilation, causing the partial pressure of oxygen in the alveoli to decrease. As a result, the pulmonary capillaries serving these alveoli will constrict, redirecting blood flow to other alveoli that are receiving sufficient ventilation.

If a person sustains an injury to the epiglottis, what would be the physiological result?

The epiglottis is a region of the larynx that is important during the swallowing of food or drink. As a person swallows, the pharynx moves upward and the epiglottis closes over the trachea, preventing food or drink from entering the trachea. If a person's epiglottis were injured, this mechanism would be impaired. As a result, the person may have problems with food or drink entering the trachea, and possibly, the lungs. Over time, this may cause infections such as pneumonia to set in.

Describe the three regions of the pharynx and their functions.

The pharynx has three major regions. The first region is the nasopharynx, which is connected to the posterior nasal cavity and functions as an airway. The second region is the oropharynx, which is continuous with the nasopharynx and is connected to the oral cavity at the fauces. The laryngopharynx is connected to the oropharynx and the esophagus and trachea. Both the oropharynx and laryngopharynx are passageways for air and food and drink.

Describe the relationship between the partial pressure of oxygen and the binding of oxygen to hemoglobin

The relationship between the partial pressure of oxygen and the binding of hemoglobin to oxygen is described by the oxygen-hemoglobin saturation/dissociation curve. As the partial pressure of oxygen increases, the number of oxygen molecules bound by hemoglobin increases, thereby increasing the saturation of hemoglobin.

Compare and contrast the right and left lungs.

The right and left lungs differ in size and shape to accommodate other organs that encroach on the thoracic region. The right lung consists of three lobes and is shorter than the left lung, due to the position of the liver underneath it. The left lung consist of two lobes and is longer and narrower than the right lung. The left lung has a concave region on the mediastinal surface called the cardiac notch that allows space for the heart.

Describe the neural factors involved in increasing ventilation during exercise.

There are three neural factors that play a role in the increased ventilation observed during exercise. Because this increased ventilation occurs at the beginning of exercise, it is unlikely that only blood oxygen and carbon dioxide levels are involved. The first neural factor is the psychological stimulus of making a conscious decision to exercise. The second neural factor is the stimulus of motor neuron activation by the skeletal muscles, which are involved in exercise. The third neural factor is activation of the proprioceptors located in the muscles, joints, and tendons that stimulate activity in the respiratory centers.

Why are the pleurae not damaged during normal breathing?

There is a cavity, called the pleural cavity, between the parietal and visceral layers of the pleura. Mesothelial cells produce and secrete pleural fluid into the pleural cavity that acts as a lubricant. Therefore, as you breathe, the pleural fluid prevents the two layers of the pleura from rubbing against each other and causing damage due to friction.

11. A section of the lung that receives its own tertiary bronchus is called the ________. a. bronchopulmonary segment b. pulmonary lobule c. interpulmonary segment d. respiratory segment

a

13. The pleura that surrounds the lungs consists of two layers, the ________. a. visceral and parietal pleurae. b. mediastinum and parietal pleurae. c. visceral and mediastinum pleurae. d. none of the above

a

14. Which of the following processes does atmospheric pressure play a role in? a. pulmonary ventilation b. production of pulmonary surfactant c. resistance d. surface tension

a

17. Gas flow decreases as ________ increases. a. resistance b. pressure c. airway diameter d. friction

a

19. Which of the following prevents the alveoli from collapsing? a. residual volume b. tidal volume c. expiratory reserve volume d. inspiratory reserve volume

a

21. When ventilation is not sufficient, which of the following occurs? a. The capillary constricts. b. The capillary dilates. c. The partial pressure of oxygen in the affected alveolus increases. d. The bronchioles dilate.

a

27. A low partial pressure of oxygen promotes hemoglobin binding to carbon dioxide. This is an example of the ________. a. Haldane effect b. Bohr effect c. Dalton's law d. Henry's law

a

28. Increased ventilation that results in an increase in blood pH is called ________. a. hyperventilation b. hyperpnea c. acclimatization d. apnea

a

32. A full complement of mature alveoli are present by ________. a. early childhood, around 8 years of age b. birth c. 37 weeks d. 16 weeks

a

34. When do fetal breathing movements begin? a. around week 20 b. around week 37 c. around week 16 d. after birth

a

5. What is the function of the conchae in the nasal cavity? a. increase surface area b. exchange gases c. maintain surface tension d. maintain air pressure

a

7. Which of the following are structural features of the trachea? a. C-shaped cartilage b. smooth muscle fibers c. cilia d. all of the above

a

respiratory membrane

alveolar and capillary wall together, which form an air-blood barrier that facilitates the simple diffusion of gases

10. Which of the following structures separates the lung into lobes? a. mediastinum b. fissure c. root d. pleura

b

23. The partial pressure of carbon dioxide is 45 mm Hg in the blood and 40 mm Hg in the alveoli. What happens to the carbon dioxide? a. It diffuses into the blood. b. It diffuses into the alveoli. c. The gradient is too small for carbon dioxide to diffuse. d. It decomposes into carbon and oxygen.

b

26. Which of the following occurs during the chloride shift? a. Chloride is removed from the erythrocyte. b. Chloride is exchanged for bicarbonate. c. Bicarbonate is removed from the erythrocyte. d. Bicarbonate is removed from the blood.

b

33. If a baby is born prematurely before type II cells produce sufficient pulmonary surfactant, which of the following might you expect? a. difficulty expressing fluid b. difficulty inflating the lungs c. difficulty with pulmonary capillary flow d. no difficulty as type I cells can provide enough surfactant for normal breathing

b

nasal bone

bone of the skull that lies under the root and bridge of the nose and is connected to the frontal and maxillary bones

bronchiole

branch of bronchi that are 1 mm or less in diameter and terminate at alveolar sacs

12. The ________ circulation picks up oxygen for cellular use and drops off carbon dioxide for removal from the body. a. pulmonary b. interlobular c. respiratory d. bronchial

c

15. A decrease in volume leads to a(n) ________ pressure. a. decrease in b. equalization of c. increase in d. zero

c

22. Gas exchange that occurs at the level of the tissues is called ________. a. external respiration b. interpulmonary respiration c. internal respiration d. pulmonary ventilation

c

24. Oxyhemoglobin forms by a chemical reaction between which of the following? a. hemoglobin and carbon dioxide b. carbonic anhydrase and carbon dioxide c. hemoglobin and oxygen d. carbonic anhydrase and oxygen

c

31. The olfactory pits form from which of the following? a. mesoderm b. cartilage c. ectoderm d. endoderm

c

35. What happens to the fluid that remains in the lungs after birth? a. It reduces the surface tension of the alveoli. b. It is expelled shortly after birth. c. It is absorbed shortly after birth. d. It lubricates the pleurae

c

4. Which of the following anatomical structures is not part of the conducting zone? a. pharynx b. nasal cavity c. alveoli d. bronchi

c

8. Which of the following structures is not part of the bronchial tree? a. alveoli b. bronchi c. terminal bronchioles d. respiratory bronchioles

c

9. What is the role of alveolar macrophages? a. to secrete pulmonary surfactant b. to secrete antimicrobial proteins c. to remove pathogens and debris d. to facilitate gas exchange

c

alar cartilage

cartilage that supports the apex of the nose and helps shape the nares; it is connected to the septal cartilage and connective tissue of the alae

larynx

cartilaginous structure that produces the voice, prevents food and beverages from entering the trachea, and regulates the volume of air that enters and leaves the lungs

respiratory epithelium

ciliated lining of much of the conducting zone that is specialized to remove debris and pathogens, and produce mucus

alveolar sac

cluster of alveoli

bronchial tree

collective name for the multiple branches of the bronchi and bronchioles of the respiratory system

philtrum

concave surface of the face that connects the apex of the nose to the top lip

type II alveolar cell

cuboidal epithelial cells that are the minor cell type in the alveolar wall; secrete pulmonary surfactant

16. The pressure difference between the intra-alveolar and intrapleural pressures is called ________. a. atmospheric pressure b. pulmonary pressure c. negative pressure d. transpulmonary pressure

d

18. Contraction of the external intercostal muscles causes which of the following to occur? a. The diaphragm moves downward. b. The rib cage is compressed. c. The thoracic cavity volume decreases. d. The ribs and sternum move upward.

d

20. Gas moves from an area of ________ partial pressure to an area of ________ partial pressure. a. low; high b. low; low c. high; high d. high; low

d

25. Which of the following factors play a role in the oxygen-hemoglobin saturation/dissociation curve? a. temperature b. pH c. BPG d. all of the above

d

29. Exercise can trigger symptoms of AMS due to which of the following? a. low partial pressure of oxygen b. low atmospheric pressure c. abnormal neural signals d. small venous reserve of oxygen

d

30. Which of the following stimulates the production of erythrocytes? a. AMS b. high blood levels of carbon dioxide c. low atmospheric pressure d. erythropoietin

d

6. The fauces connects which of the following structures to the oropharynx? a. nasopharynx b. laryngopharynx c. nasal cavity d. oral cavity

d

bronchoconstriction

decrease in the size of the bronchiole due to contraction of the muscular wall

alveolar macrophage

immune system cell of the alveolus that removes debris and pathogens

respiratory zone

includes structures of the respiratory system that are directly involved in gas exchange

bronchodilation

increase in the size of the bronchiole due to contraction of the muscular wall

cardiac notch

indentation on the surface of the left lung that allows space for the heart

dorsum nasi

intermediate portion of the external nose that connects the bridge to the apex and is supported by the nasal bone

thyroid cartilage

largest piece of cartilage that makes up the larynx and consists of two lamina

epiglottis

leaf-shaped piece of elastic cartilage that is a portion of the larynx that swings to close the trachea during swallowing

lingual tonsil

lymphoid tissue located at the base of the tongue

paranasal sinus

one of the cavities within the skull that is connected to the conchae that serve to warm and humidify incoming air, produce mucus, and lighten the weight of the skull; consists of frontal, maxillary, sphenoidal, and ethmoidal sinuses

true vocal cord

one of the pair of folded, white membranes that have a free inner edge that oscillates as air passes through to produce sound

palatine tonsil

one of the paired structures composed of lymphoid tissue located anterior to the uvula at the roof of isthmus of the fauces

meatus

one of three recesses (superior, middle, and inferior) in the nasal cavity attached to the conchae that increase the surface area of the nasal cavity

glottis

opening between the vocal folds through which air passes when producing speech

alveolar pore

opening that allows airflow between neighboring alveoli

vestibular fold

part of the folded region of the glottis composed of mucous membrane; supports the epiglottis during swallowing

bridge

portion of the external nose that lies in the area of the nasal bones

cricoid cartilage

portion of the larynx composed of a ring of cartilage with a wide posterior region and a thinner anterior region; attached to the esophagus

nasopharynx

portion of the pharynx flanked by the conchae and oropharynx that serves as an airway

oropharynx

portion of the pharynx flanked by the nasopharynx, oral cavity, and laryngopharynx that is a passageway for both air and food

fauces

portion of the posterior oral cavity that connects the oral cavity to the oropharynx

external nose

region of the nose that is easily visible to others

conducting zone

region of the respiratory system that includes the organs and structures that provide passageways for air and are not directly involved in gas exchange

laryngeal prominence

region where the two lamina of the thyroid cartilage join, forming a protrusion known as "Adam's apple"

alveolar duct

small tube that leads from the terminal bronchiole to the respiratory bronchiole and is the point of attachment for alveoli

alveolus

small, grape-like sac that performs gas exchange in the lungs

trachealis muscle

smooth muscle located in the fibroelastic membrane of the trachea

fibroelastic membrane

specialized membrane that connects the ends of the C-shape cartilage in the trachea; contains smooth muscle fibers

respiratory bronchiole

specific type of bronchiole that leads to alveolar sacs

type I alveolar cell

squamous epithelial cells that are the major cell type in the alveolar wall; highly permeable to gases

pharyngeal tonsil

structure composed of lymphoid tissue located in the nasopharynx

pulmonary surfactant

substance composed of phospholipids and proteins that reduces the surface tension of the alveoli; made by type II alveolar cells

apex

tip of the external nose

trachea

tube composed of cartilaginous rings and supporting tissue that connects the lung bronchi and the larynx; provides a route for air to enter and exit the lung

bronchus

tube connected to the trachea that branches into many subsidiaries and provides a passageway for air to enter and leave the lungs

nasal septum

wall composed of bone and cartilage that separates the left and right nasal cavities