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A&P 303 > 4/12 Lecture E1 > Flashcards

4/12 Lecture E1 Flashcards

1
Q

Approximately how many alveoli are in each lung?

A

150 million

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2
Q

What type of cells make up 95% of alveoli surface area?

A

Squamous (type 1) alveolar cells

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3
Q

What type of cells make up 5% of alveolar surface?

A

Round to cuboidal cells (type II)

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4
Q

What is the role of type II alveolar cells?

A

repair the alveolar epithelium when type I cells are damaged.

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5
Q

What do type II cells secrete and why?

A

pulmonary surfactant: a mix of phospholipids and proteins that coats the alveoli and prevents them from collapsing during exhalation.

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6
Q

What is the most numerous of all cells in the lung?

A

Alveolar macrophages (dust cells)

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7
Q

What do alveolar macrophages do?

A

wander lumens and keep alveoli free from debris by phagocytizing dust particles

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8
Q

What separates alveolar air from blood?

A

respiratory membrane

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9
Q

What does the respiratory membrane consist of?

A

squamous alveolar cells, endothelial cells of blood capillary, and their shared basement membrane

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10
Q

What is the membrane that closely covers the lungs?

A

visceral pleura

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11
Q

What adheres to the mediastinum, inner surface of the rib cage and the superior surface of the diaphragm?

A

Parietal pleura

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12
Q

What is the function of the pleurae and pleural fluid?

A

1) reduce friction
2) create pressure gradient: assists lung inflation
3) compartmentalization: prevents the spread of infection

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13
Q

What does the diaphragm do?

A

Prime mover of respiration: contraction pulls air into the lungs, relaxation bulges the muscle and compresses the lungs and expelling the air.

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14
Q

What is the purpose of internal and external intercostal muscles?

A

synergists to diaphragm. stiffen the thoracic cage during respiration. Prevents rib cage from caving inward when diaphragm descends. Add about 1/3 of the air that ventilates the lungs

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15
Q

what do the scalenes do?

A

synergist to diaphragm, fix or elevate ribs 1 and 2

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16
Q

What does muscle relaxation during normal respiration do?

A

recoils structures and results in airflow out of the lungs.

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17
Q

During forced expiration, what does the rectus abdominis do?

A

pulls down on sternum and ribs

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18
Q

What causes increased thoracic pressure?

A

increased abdominal pressure pushing viscera up against diaphragm. This forces air out.

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19
Q

Automatic, unconscious cycle of breathing is controlled by what?

A

three hairs of respiratory centers in the reticular formation of the medulla oblongata and the pons

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20
Q

What are the two respiratory groups in the MEDULLA?

A

Ventral respiratory group and the Dorsal respiratory group

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21
Q

What is another word for quiet unlabored breathing?

A

eupnea

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22
Q

What is the primary generator of the respiratory rhythm?

A

Ventral respiratory group

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23
Q

What nerve do inspiratory neurons fire to the diaphragm through and for how long?

A

Phrenic nerve, two seconds

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24
Q

how long do expiratory neurons fire in eupnea?

A

3 seconds

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25
Q

What is the respiratory rhythm produced by the VRG?

A

12 breaths per minute

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26
Q

which respiratory network in the medulla modifies the rate and depth of breathing?

A

Dorsal respiratory group

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27
Q

What is the respiratory network in the pons?

A

Pontine respiratory group

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28
Q

What does the pontine respiratory group do?

A

1) modifies rhythm of the VRG by outputs to both the VRG and DRG
2) adapts breathing to special circumstances

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29
Q

What happens during hyperventilation?

A

1) CO2 levels drop and pH rises causing cerebral arteries to constrict, reducing cerebral perfusion

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30
Q

What are central chemoreceptors?

A

brainstem neurons that respond to changes in pH of cerebrospinal fluid

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31
Q

What does the pH of cerebrospinal fluid reflect?

A

CO2 level in the blood

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32
Q

Where are peripheral chemoreceptors located?

A

carotid and aortic bodies of the large arteries above the heart

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33
Q

What do peripheral chemoreceptors respond to?

A

O2, CO2, and pH of the blood

34
Q

Where are stretch receptors found?

A

smooth muscles of bronchi and bronchioles, and in the visceral pleura

35
Q

What do stretch receptors respond to and which nerve do they use?

A

inflation of the lungs via the vagus nerve

36
Q

What is the inflation reflex also called?

A

Hering-Breuer reflex

37
Q

What is the inflation reflex triggered by?

A

excessive inflation

38
Q

What does the inflation reflex do?

A

its a reflective reflex that inhibits inspiratory neurons and stops inspiration.

39
Q

What are the irritant receptors?

A

nerve endings amid the epithelial cells of the airway

40
Q

What do irritant receptors respond to?

A

smoke, dust, pollen, chemical fumes, cold air and excess mucous

41
Q

What do irritant receptors trigger?

A

Protective reflexes such as bronchoconstriction, shallower breathing, breath-holding (apnea), or coughing

42
Q

Where does voluntary control of breathing originate?

A

in the motor cortex of frontal lobe of the cerebrum.

43
Q

How does voluntary control happen?

A

Impulses are send from the motor cortex of the frontal lobe of the cerebrum down corticospinal tracts to respiratory neurons in spinal cord, bypassing brainstem

44
Q

What is the limit to voluntary control?

A

The breaking point is when CO2 levels rise to a point where automatic controls override one’s will.

45
Q

True or false: respiratory airflow is governed by the same principles of flow, pressure, and resistance as blood flow.

A

True

46
Q

What are the principles of respiratory airflow?

A

1) the flow of a fluid is directly proportional to the pressure difference between two points
2) the flow of a fluid is inversely proportional to the resistance.

47
Q

What type of pressure drives respiration?

A

atmospheric pressure

48
Q

What is atmospheric pressure?

A

the weight of the air above us

49
Q

What is atmospheric pressure at sea level?

A

760 mmHg at sea level or 1 atm. Pressure is lower at hight elevations

50
Q

What is Boyle’s Law?

A

at a constant temperature, the pressure of a given quantity of gas is inversely proportional to its volume

51
Q

If the lungs contain a quantity of a gas and the lung volume increases, their internal pressure (intrapulmonary pressure) ___.

A

falls

52
Q

if the pressure falls below atmospheric pressure, air moves ___ the lungs.

A

into

53
Q

If the lung volume decreases, intrapulmonary pressure ____.

A

rises

54
Q

if the pressure of the lungs rises above atmospheric pressure, air moves ___ of the lungs.

A

out

55
Q

What is the unit of pressure used by respiratory physiologists?

A

cm H2O

56
Q

which is more sensitive: mmHg or cm H2O?

A

cm H2O

57
Q

What is intrapleural pressure?

A

the slightly negative pressure that exists between the two pleural layers

58
Q

what causes intrapleural pressure?

A

the recoil of lung tissue and tissues of thoracic cage causes lungs and chest wall to be pulling in opposite directions. the small space between the parietal and visceral pleura is filled with watery fluid, and they cling together. A negative 5 sm H2O pressure results.

59
Q

What happens to the alveoli during inspiration?

A

They stretch within the lungs

60
Q

As the thoracic cage increases in volume, what happens to the internal pressure?

A

The pressure drops and air flows in.

61
Q

What is Charles’ Law?

A

volume of a gas is directly proportional to its absolute temperature

62
Q

Specific to anatomy, what is Charles’ Law?

A

warming of the air expands the lungs. The air is warmed as it moves through the tubing to the alveoli.

63
Q

How is relaxed expiration mainly achieved?

A

Elastic recoil of the thoracic cage

64
Q

What is the intrapulmonary pressure during relaxed expiration?

A

about 1 cm H2O

65
Q

Why does air flow out during relaxed expiration?

A

Air flows down the pressure gradient

66
Q

During forced breathing, what happens to the intrapulmonary pressure?

A

Accessory muscles raise the pressure as high as +40 cm H2O

67
Q

What is Pneumothorax?

A

The presence of air in pleural cavity

68
Q

What does a pneumothorax result in?

A

loss of negative intrapleural pressure allows lungs to recoil and collapse

69
Q

What is atelectasis?

A

Collapse of part or all of a lung

70
Q

What can atelectasis result from?

A

An airway obstruction as blood absorbs gases from blood

71
Q

What two factors influence airway resistance?

A

1) bronchiole diameter

2) pulmonary compliance

72
Q

What stimulates bronchodilation?

A

Epinephrine and sympathetics stimulate dilation

73
Q

What does bronchodilation result in?

A

increased airflow

74
Q

What stimulates bronchoconstriction?

A

Histamine, parasympathetic nerves, cold air, and chemical irritants

75
Q

What does bronchoconstriction result in?

A

decreased airflow

76
Q

What does extreme bronchoconstriction result in and what is a potential cause?

A

Extreme constriction can cause suffocation. This can be caused by anaphylactic shock of asthma

77
Q

What is pulmonary compliance?

A

Ease with which the lungs can expand

78
Q

What can reduce pulmonary compliance?

A

degenerative lung diseases in which the lungs are stiffened by scar tissue

79
Q

What is compliance limited by?

A

the surface tension of the water film inside alveoli

80
Q

What causes infant respiratory distress syndrome?

A

premature babies lacking surfactant

81
Q

RX for infant respiratory distress syndrome

A

artificial surfactant until they can make their own

A&P 303 (18 decks)

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