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MCAT: Biology > Chapter 6: The Respiratory System > Flashcards

Chapter 6: The Respiratory System Flashcards

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1
Q

How does air enter the respiratory tract?

A

Through the external nares of the nose, and then passes through the nasal cavity

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2
Q

How is air filtered in the nasal cavity?

A

Through mucous membranes and nasal hairs (vibrissae)

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3
Q

Which structure is a common pathway for air destined for the lungs and food destined for the esophagus?

A

Pharynx

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4
Q

Where does the air go following the nasal cavity?

A

The pharynx, then the larynx

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5
Q

How is food kept out of the respiratory tract?

A

The opening of the larynx (glottis) is covered by the epiglottis during swallowing

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6
Q

Which structure contains vocal cords? How many?

A

The larynx contains two

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7
Q

From the larynx, where does air pass?

A

Into the tracea and then into one of the two mainstem bronchi

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8
Q

How is air filtered in the bronchi and trachea?

A

They contain ciliated epithelial cells to catch remaining material

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9
Q

In the lungs, the bronchi continue to divide into smaller structures known as ____________, which divide further into _________

A

bronchioles alveoli

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10
Q

Gas exchange occurs where?

A

At the alveoli

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11
Q

What is each alveolus coated with? Why?

A
  • A surfactant (detergent) - Lowers surface tension and prevents the alveolus from collapsing on itself
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12
Q

Membranes known as _______ surround each lung

A

pleurae

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13
Q

The surface adjacent to the lung is the _______ pleura, and the outer part is the _______ pleura

A

visceral parietal

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14
Q

What does the diaphragm divide?

A

Divides the thoracic (chest) cavity from the abdominal cavity

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15
Q

The diaphragm is under (somatic/automatic) control, and breathing is under (somatic/automatic)

A

somatic automatic

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16
Q

What does the intrapleural space contain? Why?

A

Thin layer of pleural fluid, which helps lubricate the two pleural surfaces

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17
Q

What ultimately drives breathing?

A

The pressure differentials that can be created across the pleura drives air into the lungs

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18
Q

What structures do we use to expand the thoracic cavity?

A

Diaphragm and external intercostal muscles

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19
Q

What happens when the diaphragm flattens and the chest wall expands? Why?

A

The intrathoracic volume increases, and the intrapleural space approaches the chest wall, which increases its volume

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20
Q

What is Boyle’s law? How does it relate to breathing?

A
  • States that the pressure and volume of gases are inversely related - As the chest wall expands, the pressure in the lungs drop, and air is drawn into the lungs
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21
Q

When breathing in, what happens to the intrapleural pressure?

A

The intrapleural volume increases, so the pressure decreases

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22
Q

When breathing in, how does the pressure of the lungs compare to the pressure of the intrapleural space? What does that cause?

A
  • The pressure of the lungs is higher than the pressure of the intrapleural space - The lungs will therefore expand into the intrapleural space, and the pressure in the lungs will drop - Air will be sucked in from the high-pressure environment (outside world)
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23
Q

What is negative-pressure breathing?

A

The driving force is the lower (relatively negative) pressure in the intrapleural space compared with the lungs

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24
Q

How does exhalation occur? Is it an active process?

A
  • Does not have to be an active process - Relaxation of the external intercostal muscles and diaphragm
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25
Q

When breathing out, what happens to the pressure in the intrapleural space?

A
  • Chest cavity decreases in volume - Intrapleural space pressure is higher than in the lungs, which results in air being pushed out
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26
Q

How can we speed exhalation?

A

By using the internal intercostal muscles and abdominal muscles

27
Q

What is the instrument used in lung capacity and volume measurements?

A

Spirometer

28
Q

What is total lung capacity (TLC)? What is it usually around?

A
  • The maximum volume of air in the lungs when one inhales completely - Usually around 6 to 7 liters
29
Q

What is residual volume (RV)?

A

The minimum volume of air in the lungs when one exhales completely

30
Q

What is vital capacity (VC)?

A

The difference between the minimum and maximum volume of air in the lungs (TLC - RV)

31
Q

What is tidal volume (TV)?

A

The volume of air inhaled and exhaled in a normal breath

32
Q

What is expiratory reserve volume (ERV)?

A

The volume of additional air that can be forcibly exhaled after a normal exhalation

33
Q

What is inspiratory reserve volume (IRV)?

A

The volume of additional air that can be forcibly inhaled after a normal inhalation

34
Q

What is ventilation primarily regulated by?

A

Collection of neurons in the medulla oblongata called the ventilation center

35
Q

What kind of receptors are neurons in the ventilation center?

A

They contain chemoreceptors that are primarily sensitive to carbon dioxide concentration

36
Q

What is hypercarbia (or hypercapnia)?

A

When there is a high concentration of carbon dioxide in the blood

37
Q

What happens when there is a high concentration of carbon dioxide in the blood?

A

The respiratory rate will increase so that more CO2 is exhaled

38
Q

What is hypoxia?

A

Low oxygen concentration in the blood

39
Q

How does the ventilation center respond to hypoxia?

A

Increases the ventilation rate

40
Q

How can ventilation be controlled consciously? What structure will override it?

A
  • Controlled consciously through the cerebrum - The medulla oblongata will override during extended periods of hypo- or hyperventilation
41
Q

List the structures in the respiratory pathway, from where air enters the nares to the alveoli.

A

Nares, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveoli

42
Q

What is the mathematical relationship between vital capacity (VC), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), and tidal volume (TV)?

A

VC = IRV + ERV + TV

43
Q

The capillaries bring deoxygenated blood from the _____________, which originate from the _______ _________ of the heart.

A

pulmonary arteries right ventricle

44
Q

The oxygenated blood returns to the _____ ______ f the heart via the _____________.

A

left atrium pulmonary veins

45
Q

When it initially arrives at the alveoli, blood has a relatively (low/high) partial pressure of oxygen, and a relatively (low/high) partial pressure of carbon dioxide

A

low high

46
Q

What happens if we moved to higher altitudes where less oxygen is available?

A

1) Breathe more rapidly to try to avoid hypoxia 2) Binding of hemoglobin to oxygen is altered to facilitate the unloading of oxygen at the tissues 3) Make more red cells to carry oxygen 4) Long run: develop more blood vessels (vascularization), which would facilitate the distribution of oxygen to tissues

47
Q

What is the natural response of hemoglobin to decreased carbon dioxide concentration in the environment?

A

Decrease the unloading of oxygen to tissues

48
Q

How is heat regulated through body surfaces?

A
  • Vasodilatation and vasoconstriction - Sweat glands - Rapid muscle contraction (shivering)
49
Q

What happens in terms of thermal energy during vasodilatation?

A

When capillaries expand, more blood can pass through these vessels, and a larger amount of thermal energy can be dissipated

50
Q

What happens in terms of thermal energy during vasoconstriction?

A

When capillaries contract, less blood can pass through them, conserving thermal energy

51
Q

What is the first line of immune defense in the respiratory system?

A

Occurs within the nasal cavity, the small hairs (vibrissae) help to trap particulate matter and potentially infectious particles

52
Q

What enzyme does the nasal cavity contain? What is its function?

A
  • Lysozyme - Able to attack the peptidoglycan walls of gram-positive bacteria
53
Q

What is the mucociliary escalator mechanism?

A
  • The internal airways are lined with mucus, which traps particulate matter and larger invaders - Underlying cilia then propel the mucus up the respiratory tract to the oral cavity, where it can be expelled or swallowed
54
Q

What kind of immune cells do the lungs contain?

A
  • Macrophages - Mast cells
55
Q

What is the function of macrophages?

A

Engulf and digest pathogens, and signal to the immune system of an invader

56
Q

What helps protect against pathogens that contact the mucous membranes?

A

Mucosal surfaces contain IgA antibodies

57
Q

What is the function of mast cells?

A
  • Preformed antibodies on their surface - When the right substance attaches to the antibody, it releases inflammatory chemicals into the surrounding area to promote an immune response
58
Q

Which immune cells provide the inflammatory chemicals that mediate allergic reactions?

A

Mast cells

59
Q

What is the regular pH of the body?

A

7.35 to 7.45

60
Q

What happens during acidemia?

A
  • Acid-sensing chemoreceptors signals the brain to increase respiratory rate - Increased H+ causes a shift in the bicarbonate buffer system, which generates more CO2 - Increased CO2 increases respiratory rate - CO2 is blown off, and the system shifts to the left, which lowers the amount of H+
61
Q

What happens during alkalemia?

A
  • Respiratory rate is slowed, which retains more CO2 - System is shifted to the left, producing more H+ and bicarbonate ions
62
Q

What is the role of the kidneys in the maintenance of proper pH?

A

By modulating secretion and reabsorption of acid and base within the nephron

63
Q

Respiratory failure refers to inadequate ventilation to provide oxygen to the tissues. How would the pH change in respiratory failure?

A
  • Less CO2 is blown off - Buffer equation shifts to the right, and more hydrogen ions are generated - Lower pH of the blood
64
Q

What is the bicarbonate buffer system equation?

A

CO2(g) + H2O(l) ⇔ H2CO3(aq) ⇔ H+(aq) + HCO3-(aq)

MCAT: Biology (12 decks)

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