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HUBS192 > Respiratory System > Flashcards

Respiratory System Flashcards

1
Q

Describe the role of the respiratory system.

A

Connected organs and structures that function to conduct warm, clean, moist air into close proximity with blood of the circulatory system for gas exchange.

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2
Q

Name the main components of the respiratory system.

A 
URT Upper respiratory tract
LRT Lower respiratory tract
Thoracic cavity
Joints
Respiratory muscles
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3
Q

Where is the conducting region of the respiratory system, and what is its function?

A

From the nose to bronchioles.

Ensures the air is warm, moist and clean.

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4
Q

Where is the respiratory region of the respiratory system, and what is its function?

A

Alveoli

Sites of gas exchange

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5
Q

What are the primary and secondary passageways for air into the respiratory system?

A

Nasal cavity

Oral cavity

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6
Q

Briefly describe the components of mucosa and submucosal layer lining most body organs.

A

Epithelia, attached via a basement membrane to the lamina propria (connective tissue + maybe glands).

Submucosal layer sits under the mucosa, and may contain many glands.

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7
Q

Name the types of epithelium along the respiratory tract for these functions: most of conducting region, where air and food travel, site of gas exchange, and olfaction.

A

Respiratory epithelium
Stratified squamous epithelium
Simple squamous epithelium
Olfactory mucosa

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8
Q

Describe respiratory epithelium. Where is it found?

A

Pseudostratified ciliated columnar epithelium with goblet cells. Found in nasal cavity, part of pharynx, larynx, trachea and bronchi.

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9
Q

What is the function of goblet cells in respiratory epithelium?

A

Produce mucus with traps debris (cleaning), and moistens the air.

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10
Q

Why is respiratory epithelium ciliated?

A

Its movement pushes dirty mucus towards the pharynx, which is then swallowed and digested by stomach acid.

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11
Q

Name the components of the URT.

A

Nose and nasal cavity
Paranasal sinuses
Pharynx

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12
Q

What are the functions of the URT?

A

Conducts air and food.
Prepares air for respiratory membrane- warm, moist, clean.
Provides resonating chambers for speech.
Provide olfaction (sense of smell).

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13
Q

Describe the components of the nose. (3)

A

Cartilages- soft, flexible, maintain unobstructed airway
External/ anterior nares (nostrils)
Vestibule- inside space lined with skin, has sebaceous and sweat glands, and vibrissae (hairs)

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14
Q

What do vibrissae do?

A

First step in filtering and cleaning air.

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15
Q

Which bones form the nasal cavity?

A

Ethmoid and sphenoid bones form the roof.
Hard and soft palates form the floor.
Conchae (bony projections) on lateral walls.
Internal/ posterior nares open from back of cavity into pharynx.

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16
Q

What is the other name for conchae, and why?

A

Turbinates- they swirl the air to make it stick to the mucosa. This allows more time for warming and humidifying, plus olfactory detection.

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17
Q

Name the three conchae/ turbinates.

A

Superior, middle and inferior.

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18
Q

Which epithelium lines the nasal cavity?

A

Mostly respiratory epithelium, and some olfactory mucosa on the roof.

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19
Q

Describe the nasal muscosa.

A

Lamina propria (connective tissue) underneath epithelium contains a plexus of thin-walled veins that help warm incoming air via radiation.

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20
Q

What happens in the nasal mucosa when the air temperature drops?

A

The vascular plexus dilates, allowing for greater heat transfer to the air.

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21
Q

Define sinus.

A

A cavity within a bone, usually filled with air.

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22
Q

Where are paranasal sinuses found?

A

Within the frontal, sphenoid, ethmoid and maxillary bones. They drain into the pharynx.

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23
Q

What separates the nasal cavity in half?

A

Nasal septum- into L and R- anterior is cartilage, posterior is bone.

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24
Q

What lines the paranasal sinuses?

A

Respiratory mucosa.

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25
Q

Name the functions of the paranasal sinuses.

A

Lighten the skull
Increase the SA to clean, warm and moisten air.
Provide sound resonance.

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26
Q

What are blocked sinuses?

A

When the paranasal sinuses become filled with infected mucus that blocks drainage.

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27
Q

Describe the pharynx.

A 
Muscular funnel-shaped tube shared by respiratory and digestive system.
Made up of three regions:
- nasopharynx
- oropharynx
- laryngopharynx
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28
Q

Describe the location, structure and function of the nasopharynx, and name the structures it includes.

A

Allows air passage only (respiratory epithelium).
Runs from the posterior/ internal nares to soft palate.
Posterior to the nasal cavity.
Includes structures: pharyngeal tonsils/ adenoids and auditory tube.

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29
Q

Why doesn’t food enter the nasal cavity when swallowing?

A

The soft palate and uvula block the nasopharynx.

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30
Q

What is the name of the lymphoid tissue that sits in the nasopharynx, and can block off airway if swollen?

A

Pharyngeal tonsils/ adenoids.

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31
Q

Describe the functions of the auditory tube in the nasopharynx.

A

Allows mucus to drain from the middle ear, and the equalisation of pressure by opening the tube.

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32
Q

Describe the location, structure and function of the oropharynx, and the structures it includes.

A

Allows air and food passage (stratified squamous epithelium for protection against abrasion).
Posterior to the oral cavity.
Runs from soft palate to hyoid bone.
Includes structures: palatine tonsils and lingual tonsils.

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33
Q

Name the location of the lingual tonsils.

A

Behind/ under the tongue.

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34
Q

Why can the palatine tonsils be problematic?

A

If they become inflamed, they will block both airways from the nose and mouth.

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35
Q

Describe the location, structure and function of the laryngopharynx.

A

Allows air and food passage (stratified squamous epithelium for protection against abrasion).
Runs from hyoid bone to opening of larynx/ beginning of esophagus- where respiratory and digestive tracts diverge.

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36
Q

Name the components of the LRT. (5)

A 
Larynx
Trachea
Bronchi
Bronchioles
Alveoli
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37
Q

Name three functions of the LRT.

A

Conducts air to/ from site of gas exchange.
Completes warming, cleaning and humidifying the air.
Provides a large SA barrier between the air and blood.

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38
Q

Describe the location and function of the larynx, and the structures it involves.

A

Passage only for air.
Anterior to the esophagus.
Runs from the hyoid bone to trachea.
Includes structures: cricoid cartilage, thyroid cartilage, epiglottis, glottis

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39
Q

Describe the function of epiglottis.

A

When we swallow, the tongue pushes backwards, putting pressure on the epiglottis which flaps over the larynx, closing the airway and preventing food from passing into it.

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40
Q

What is the name of the structure that forms the adam’s apple?

A

Laryngeal prominence (part of thyroid cartilage).

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41
Q

Define the glottis.

A

The “voicebox” which contains vocal folds/ chords and vestibular folds/ chords.

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42
Q

Describe the difference between vocal folds and vestibular folds.

A 
Vocal folds produce normal sound.
Vestibular folds (superior to vocal folds) are there for protection. They prevent entry of foreign objects, but can also produce very deep sounds.
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43
Q

Why are mens’ voices generally deeper than females’?

A

Testosterone enlarges cartilage and muscle, including those surrounding the vocal folds. This results in longer, thicker folds, which are capable of producing deeper vibrations.

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44
Q

Describe the location, structure and function of the trachea, and the structures it involves.

A

Passage for air between larynx and primary bronchi.
Sits anterior to esophagus.
Lined with respiratory epithelium.
Rings of C-shaped cartilage are connected by the trachealis.
Contains many elastin fibres in lamina propria and submucosal layers.

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45
Q

Name two functions of the trachealis muscle.

A

Maintains patent airway.

Contracts for coughing to eject particles out of the airway. (elastin fibres help with recoil of cough)

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46
Q

What do we use to remove foreign particles from the LRT?

A

Mucociliary escalator- works against gravity.

  • goblet cells producing mucus which traps particles
  • cilia beating mucus up to pharynx to be swallowed and digested
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47
Q

Describe the basic structure and location of the lungs.

A

2 lungs: left lung has 2 lobes, right lung has 3 lobes.
Heart takes up lots of space on the left.
The apex of each lung sits under the clavicle, and the dome-shaped base sits on the diaphragm.
Costal surface sits against the ribs.

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48
Q

What is the hilum of an organ? What is different about the hilum of the lung?

A

The place where blood vessels, nerves and lymphatics enter and exit the organ.

Bronchi also enter through here.

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49
Q

Describe the branching of the bronchial tree.

A

Trachea branches into primary bronchi (through hilum- one left, one right).
Into secondary/ lobar bronchi (head to the lobes- two on left, three on right)
Into tertiary/ segmental bronchi
Into bronchioles
Lots more branching before reaching the terminal bronchioles that go into the alveoli.

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50
Q

Describe the epithelium throughout the bronchial tree.

A

1 bronchi- respiratory epithelium
2 and 3 bronchi- respiratory epithelium starts to decrease in height, goes towards cuboidal, goblet cell numbers reduce
Bronchioles- cuboidal epithelium, no goblet cells

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51
Q

Describe how the tubes throughout the bronchial tree are kept open.

A

Trachea- C-shaped cartilage
1 bronchi- complete rings of cartilage and smooth muscle
2 and 3 bronchi- cartilage plates (patches), there is enough pressure to keep them open
Bronchioles- thick smooth muscle, no cartilage

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52
Q

Each terminal bronchiole supplies a _______ ________.

A

Pulmonary lobule

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53
Q

Describe the respiratory zone of the LRT.

A

Pulmonary lobules made up of many alveoli arranged in bunches, and covered in a fine network of pulmonary capillaries.

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54
Q

How many alveoli per lung?

A

~150 million (take up most of lung volume and have a large SA)

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55
Q

Describe alveolus structure.

A

Open at one side (pocket-like)

Very thin wall- simple squamous epithelium on a thin basement membrane

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56
Q

Define pneumocytes, and name two types.

A

Lung epithelial cells.
Type I squamous
Type II cuboidal

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57
Q

Describe type I pnuemocytes.

A

Form the respiratory membrane for gas exchange with capillary wall and shared basement membrane. Squamous

58
Q

Describe type II pneumocytes.

A

Scattered amongst type I.

Secrete surfactant- a complex lipoprotein that reduces surface tension of alveolar fluid.

59
Q

What other cell roams the alveoli?

A

Roaming macrophages- remove debris that makes it to alveoli.

60
Q

Describe the respiratory membrane/ blood air barrier.

A

Alveolar cell layer (simple squamous epithelium)
Capillary endothelium (simple squamous endothelium)
With basement membranes fused together

61
Q

Name the components of the serous membrane lining the pleura.

A

Parietal pleura facing chest wall.
Visceral pleura in contact with the lung.
Pleural cavity filled with pleural fluid.

62
Q

Name the functions of the pleural fluid.

A

Slippery surface allows frictionless movement.

Fluid bond causes lungs to ‘stick’ to thoracic wall, so they can expand and contract with it.

63
Q

Name the boundaries of the thoracic cavity.

A 
Anterior: sternum
Posterior: thoracic vertebrae
Lateral: ribs
Superior: base of neck
Inferior: diaphragm
64
Q

Why are the pleural cavities separate?

A

If one lung stops functioning because of damage to the pleura, it doesn’t affect the other.

65
Q

Describe Boyle’s law.

A

Pressure is inversely proportional to volume (P=1/V)

  • smaller volume = more collisions = increased pressure
  • larger volume = less collisions = decreased pressure
66
Q

What do we need to establish in order to move air in and out of the lungs?

A

A pressure gradient.

67
Q

Describe the pressure gradient for between breaths, breathing in, and breathing out.

A

Between- no gradient because pressure inside cavity= pressure outside cavity
In- increasing volume creates a gradient into the lungs into lower pressure
Out- decreasing volume creates a gradient out of the lungs into lower pressure

68
Q

Describe the three types of anterior thoracic joints.

A

Sternocostal- between sternum and cartilage, all synovial except cartilaginous first joint

Costochondral- between cartilage and ribs, cartilaginous

Interchondral- between cartilage and cartilage, synovial

69
Q

Why is the sternocostal joint between the first rib and sternum cartilaginous?

A

To provide stability.

70
Q

Describe the posterior thoracic joints.

A

Costotransverse- between rib and transverse process of vertebrae, synovial

Costovertebral- between rib and body of vertebrae

71
Q

Name the primary inspiratory muscles.

A

Diaphragm and intercostal muscles.

72
Q

What name is given to other muscles that can move the rib cage?

A

Accessory muscles

73
Q

Describe the structure and movement of the diaphragm.

A

Sheet of skeletal muscle that separates the thorax from the abdomen. Dome-shaped when relaxed.

Contracts and flattens down to expand the thoracic cavity and compress the abdominopelvic cavity.

74
Q

Describe the structure and function of the two types of intercostal muscles.

A

Attach neighbouring ribs diagonally.

External intercostals lift the rib cage and expand the cavity. They are used for quiet and forced inspiration.

Internal intercostals depress the rib cage and decrease the cavity space. Used for forced expiration.

75
Q

Describe the accessory muscles of respiration.

A

Attach to the thoracic cage. Some increase cavity volume for forced inspiration, some decrease cavity volume for forced expiration.

76
Q

How do respiratory muscles cause normal/ quiet inspiration?

A

Diaphragm contracts and flattens which elongates the pleural cavity.
External intercostals contract and lift the rib cage.

77
Q

How do respiratory muscles cause forced inspiration?

A

As well as the contraction of diaphragm and external intercostals:
Accessory muscles contract to further expand the thoracic cavity.

78
Q

How do respiratory muscles cause normal/ quiet expiration?

A

Passive process- so no muscles are contracting.
Diaphragm relaxes to a dome shape.
External intercostals relax to bring ribs back down.

79
Q

How do respiratory muscles cause forced expiration?

A

As well as the relaxation of diaphragm and external intercostals:
Internal intercostals contract to depress rib cage
Accessory muscles contract to further decrease cavity volume.

80
Q

How do the lungs expand as the cavity does?

A

Thoracic wall movement = lung movement.
The pleura stick the lungs to the thoracic wall. Since lung tissue is elastic with recoil, it expands and decreases with the thoracic cavity.

81
Q

Which two opposing forces must be overcome to take a breath?

A

Stiffness of the lungs

Resistance of the airways

82
Q

Which two properties contribute to the stiffness of the lungs?

A

Compliance

Surface tension

83
Q

Define compliance in the lungs.

A

The magnitude of change in lung volume over the change in pressure.

84
Q

What do low compliance lungs cause?

A

Stiffness- so more work needs to be done for expansion.

85
Q

Describe Pulmonary Fibrosis.

A

Thickening and scarring of the alveolar membranes, arising from chronic inflammation/ exposure to industrial chemicals. Results in low compliance lungs.

86
Q

What causes surface tension in the lungs?

A

Attractive forces between fluid molecules lining the alveoli.

87
Q

What property of alveoli enhances their surface tension?

A

Very thin walls.

88
Q

What does a higher surface tension mean for lungs?

A

Less compliance –> stiffer lungs –> more work required

89
Q

Describe the structure and function of surfactant.

A

Mostly phospholipids (+ proteins), produced by type II pneumocytes.

Lowers surface tension by reducing the attractive forces between fluid molecules lining the alveoli + increasing compliance. (break bonding like a detergent)

90
Q

Where is the main area of airway resistance? Why?

A

Bronchi
Velocity decreases as the air moves further down the bronchial tree.
Bronchioles are in parallel, creating a large cross-sectional area.

91
Q

Define a spirometer.

A

A test that measures volume inspired and exhaled, and how fast you can breathe.

92
Q

Define tidal volume VT.

A

Volume of air moved in and out during a quiet normal breath.

93
Q

Define inspiratory reserve volume IRV.

A

Extra volume that can be inhaled over and above the tidal volume.

94
Q

Define expiratory reserve volume ERV.

A

Extra volume that can be exhaled voluntarily after completion of a normal, quiet respiratory cycle.

95
Q

Define residual volume.

A

Volume remaining in the lungs after maximal exhalation.

96
Q

Define minimal volume.

A

Volume remaining in a collapsed lung.

97
Q

Define vital capacity.

A

Maximum volume of air that can be moved in and out of your lungs. Inspiratory reserve + expiratory reserve + tidal volume.

98
Q

Define total lung capacity.

A

Total volume in lungs when it is filled to the maximum. Vital capacity + residual volume.

99
Q

Define inspiratory capacity.

A

Total volume of air that can be inspired from rest. Inspiratory reserve + tidal volume.

100
Q

Define functional residual capacity.

A

Volume remaining in lungs after normal exhalation. Expiratory reserve + residual volume.

101
Q

Define FEV1.

A

Forced expiratory volume in one second. How much of the forced vital capacity comes out in the first second.

102
Q

What is a normal FEV1/FVC ratio?

A

~ 80%

Volume of air exhaled in one sec is 80% of the total volume exhaled.

103
Q

What does a FEV1/FVC ratio of 0.70 indicate?

A

Airway obstruction –> increased airway resistance

104
Q

What is the difference between obstructive and restrictive airway issues?

A 
Obstructive = resistance to airflow e.g. asthma
Restrictive = reduced lung capacity e.g. fibrosis
105
Q

Define respiratory minute volume, and how to calculate it.

A

Litres of air entering the nose/ mouth per minute.

Tidal volume x respiratory rate

106
Q

Define alveolar ventilation.

A

Litres of air per minute being exchanged at the alveoli.

107
Q

Why is alveolar ventilation lower than respiratory minute volume?

A

It takes into account the dead space (VD)- air that fills the upper airway and doesn’t reach the alveoli.

108
Q

Why are small rapid breaths not helpful to our ventilation?

A

Because dead space doesn’t change, so total volume of air reaching the alveoli for gas exchange will be very small.

109
Q

Describe Dalton’s law.

A

Pressure of a mixture of gases = sum of the individual partial pressures.

110
Q

What determines the rate of diffusion? (Fick’s law)

A

Surface area of membranes
Thickness of the membranes
Pressure difference between the two sides

111
Q

How does CO2 diffusion constant compare to that of O2?

A

CO2 diffuses about 20x faster than O2 due to its higher solubility.

112
Q

What does the diffusion constant of a substance depend on?

A

Gas solubility and molecular weight.

113
Q

Why does the blood-air barrier have a large surface area?

A

Bulbous structure of alveoli and high density of capillaries.

114
Q

Define emphysema.

A

A diseases characterised by dilation of alveolar spaces and destruction of the alveolar walls- leads to reduction in surface area and less O2 exchange.

115
Q

Which disease lowers the rate of O2 diffusion by changing the thickness of the membrane?

A

Pulmonary fibrosis- thickening of membrane

116
Q

What is the main factor for gas diffusion?

A

Pressure difference- PAO2 vs PaO2 (partial pressure of O2 in alveoli vs partial pressure of O2 in arteries)
And PACO2 vs PaCO2

117
Q

What does PAO2 depend on? Which can be ignored and why?

A

Partial pressure of O2 in the inspired air
Alveolar ventilation
O2 consumption (shown in venous blood O2)

Partial pressure of O2 in the inspired air can be ignored because it’s usually constant- at atmospheric PO2.

118
Q

What does PACO2 depend on? Which can be ignored and why?

A

Partial pressure of CO2 in inspired air
Alveolar ventilation
CO2 production (cell metabolism)

Partial pressure of CO2 in inspired air- usually constant.

119
Q

When does gas diffusion across the blood air barrier stop?

A

When the partial pressure of that gas is equal between the alveoli and the blood.

120
Q

How is oxygen carried in the blood (2)?

A 
Dissolved O2 (about 15mL)
Bound to haemoglobin in RBCs (most)
121
Q

How much blood O2 is needed per minute?

A

250mL

122
Q

Define O2 binding to haemoglobin in an equation.

A

O2 + Hb HbO2

reversible

123
Q

What is O2 binding to Hb dependent on?

A

PO2 (partial pressure of oxygen)

124
Q

What does the O2-haemoglobin saturation curve describe?

A

The percentage of haem units containing bound oxygen (Hb saturation) at any PO2.

125
Q

What does the steep slope part of the Hb saturation curve indicate?

A

A very small change in PO2 results in a large change in the amount of oxygen bound to Hb.

126
Q

Which three factors would cause a right shift in the O2-Hb saturation curve? What does a right shift result in?

A

Reduced pH
Increased CO2
Increased temperature

More O2 released- helpful when exercising

127
Q

Which three factors would cause a left shift in the O2-Hb saturation curve? What does a left shift result in?

A

Increased pH
Decreased PCO2
Reduced temperature

Less O2 released

128
Q

How is CO2 transported in the blood (3)?

A

Dissolved in the plasma
Combined with Hb as carbaminohaemoglobin
As bicarbonate

129
Q

How does CO2 turn into bicarbonate?

A

Enters RBC
Carbonic anhydrase converts CO2 + H2O –> H2CO3 carbonic acid
Unstable carbonic acid immediately dissociates into H+ and HCO3- (bicarbonate ion)
H+ binds to Hb, bicarbonate ions move into plasma in exchange for chloride ions- called a chloride shift

130
Q

What does tight control of ventilation maintain?

A

Normal levels of O2 and CO2

131
Q

Name the major system controlling ventilation, and which locations it spans.

A

Central controller in pons, medulla and other parts of the brain.

132
Q

Name the sensors and effectors of ventilation.

A

Sensors: chemoreceptors, baroreceptors, lung stretch receptors, protective reflexes
Effectors: muscles of respiration

133
Q

Name the three levels of respiratory control and their locations.

A

Respiratory rhythmicity centres- medulla oblongata
Apneustic and pneumotaxic centres- pons
Higher centres

134
Q

Name the three respiratory rhythmicity centres and their functions.

A

Dorsal respiratory group DRG (inspiratory centre)
- send inspiratory signals to diaphragm and external intercostal muscles

Ventral respiratory group
- inspiratory and expiratory centres send signals to accessory inspiratory muscle and accessory expiratory muscles respectively

Pre-Bötzinger complex
- generates rhythm of ventilation

135
Q

What is the function of the apneustic and pneumotaxic centres?

A

Apneustic centres promote inhalation by stimulating the DRG

Pneumotaxic centres can inhibit the apneustic centre to decrease DRG activity and inhalation

136
Q

What is the function of the higher centres for respiration?

A

Can alter the activity of the pneumotaxic centres

137
Q

Describe the two types of chemoreceptors for the respiratory system.

A

Peripheral chemoreceptors- located in the carotid bodies and aortic arch (same as baroreceptors), sense changes in H+, O2 and CO2

Central chemoreceptors- located in the ventral part of the medulla, sense changes in H+, mainly due to changes in CO2

138
Q

Define hypercapnia and hypocapnia. How is homeostasis restored?

A

Hypercapnia= increased arterial PCO2
- chemoreceptors sense increase, signalling to respiratory muscles increases, respiratory rate and expulsion of CO2 increases

Hypocapnia= decreased arterial PCO2
- chemoreceptors sense decrease, signalling to respiratory muscles decrease, respiratory rate and expulsion of CO2 decreases

139
Q

How do baroreceptors affect respiratory function?

A

When they sense low bp, they send afferent signals to the medulla, respiratory minute volume increases.

When they sense high bp, respiratory minute volume goes down.

140
Q

Describe the inflation reflex of the lungs.

A

Stretch receptors in the smooth muscle surrounding bronchioles sense increased inflation and send signals to the DRG and VRG to inhibit contraction of respiratory muscles and stop inflation.

141
Q

Describe the deflation reflex of the lungs.

A

Stretch receptors in the alveolar walls sense increased deflation and send signals to the DRG and VRG to increase contraction of respiratory muscles and stop deflation.

142
Q

Describe the protective reflex of the lungs.

A

Receptors in the alveoli, lungs and airway detect irritation and send a signal to the brain which triggers a sneeze or a cough.

HUBS192 (6 decks)

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