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(PA school) Human Physiology > Lecture 8: Breathing > Flashcards

Lecture 8: Breathing Flashcards

1
Q

What is the primary function of the respiratory system?

A

Obtain O2 and eliminate CO2

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2
Q

What are the two main processes the respiratory system accomplishes? Define each.

A

1) Cellular respiration: Intracellular metabolism of mitochondria (Use O2, produce CO2).
2) External respiration: Exchange of O2 and CO2 with environment

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3
Q

1) What is the average number of breaths per minute?
2) How much air is this per minute?

A

1) 12-15
2) 7L of air per min into the lungs

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4
Q

Gas exchange can increase ________ from baseline if needed

A

20x

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5
Q

What are the two stages of respiration in order?

A

First stage: Gas exchange
Second Stage: Cellular respiration

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6
Q

What are the 7 non-respiratory functions of the respiratory system?

A

1) Water and heat elimination: Inspired air is humified and warmed
2) Enhanced venous return (respiratory pump)
3) Helps regulate acid-base balance (controlling rate of CO2 removal)
4) Speech and vocalization
5) Defends against inhaled foreign matter
6) Activates or inactivate various materials
7) Smell

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7
Q

Give an example of how the respiratory system activates or inactivates various materials

A

Prostaglandins are inactivated by pulmonary circulation so they cannot exert systemic effects, activates angiotensin II

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8
Q

How are the internal components of the lungs divided?

A

Into vascular tree and airway tree

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9
Q

The ___________ tree divides repeatedly to increase the lung’s surface area for gas exchange

A

airway

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10
Q

Trace the path of the respiratory airways beginning with nasal passages

A

1) Nasal passages [open into]
2) Pharynx
3) Larynx [at trachea entrance]
4) Trachea [divides into]
5) Right and left bronchi [which enter lungs]
6) Bronchi
7) Bronchioles
8) Terminal bronchiole
9) Respiratory bronchiole
10) Alveolar duct
11) Alveolar sac [w. type 1 and 2 alveolar cells]

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11
Q

1) Where do the respiratory airways begin?
2) What do these open into?
3) What does that then branch into?

A

1) Nasal passages
2) Pharynx
3) Trachea and esophagus

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12
Q

The common passage for respiratory and digestive systems is called the what?

A

Pharynx

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13
Q

Reflex mechanisms do what to the trachea and esophagus?

A

Close trachea during swallowing and keep esophagus closed except when swallowing

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14
Q

What is located at the entrance of the trachea?

A

Larynx

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15
Q

1) What is the larynx also called?
2) What is its anterior protrusion commonly called?

A

1) Voicebox
2) “Adam’s apple”

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16
Q

1) What are the vocal folds?
2) What is the glottis?
3) Which closes during swallowing?

A

1) 2 bands of elastic tissue stretched into shapes by laryngeal muscles
2) Opening between folds
3) Glottis

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17
Q

Describe how the vocal cords allow us to make sound

A

Air passing through, folds vibrate, mouth (lips, tongue, etc.) modify sound

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18
Q

The vocal folds and glottis are found where?

A

Larynx

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19
Q

Trachea divides into _________________________ which enter the lungs

A

right and left bronchi

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20
Q

Describe bronchi branching

A

Bronchi continue to branch into progressively smaller airways called bronchioles which end in alveoli

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21
Q

What type of bronchi are rigid tubes circled by cartilage rings that prevent tubes from compressing?

A

Trachea and larger bronchi

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22
Q

Describe the structure of the smaller bronchioles

A

Have no rings, they have autonomically innervated smooth muscle walls

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23
Q

What 3 things make up the conducting zone?

A

Trachea, bronchi, and terminal bronchiole

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24
Q

What are the 3 functions of the conducting zone?

A

1) Warm and humidify inspired air
2) Distribute air evenly to all regions of the lungs
3) Serve as part of the body’s defense system

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25
Q

What part of the respiratory system is subject to changes in negative and positive pressures?

A

First four generations of conducting zone

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26
Q

What can cause low compliance of the lungs?

A

Too much fibrous connective tissue (instead of normal lung tissue)

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27
Q

1) What is a characteristic of the conducting zone?
2) What circulation is here?

A

1) Large amount of cartilage to prevent collapse
2) Bronchial circulation

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28
Q

True or false: no gas exchange ever occurs at the conducting zone

A

True

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29
Q
A
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30
Q

1) The respiratory zone is made up of what generations?
2) What occurs here?

A

1) Last 7 generations
2) Site of gas exchange

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31
Q

What 3 things make up the respiratory zone?

A

1) Respiratory bronchiole
2) Alveolar duct
3) Alveolar sac

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32
Q

What circulation is in the respiratory zone? What does it touch?

A

Pulmonary circulation
70-80% of alveolar surface area

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33
Q

What has the most extensive capillary network when compared to any organ in the body?

A

Pulmonary circulation at the respiratory zone (esp. alveoli)

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34
Q

How quickly do RBCs pass through pulmonary capillaries?

A

<1 second

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35
Q

What part of the lungs are ideal for facilitating gas exchange? Give 2 reasons

A

Alveoli clusters:
1) Short distance
2) Tremendous surface area

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36
Q

1) Describe the walls of the alveoli clusters (thickness and cell type)
2) What surrounds these alveoli clusters?
3) What space is extremely thin here?
4) What membrane is 0.5µm?

A

1) Thin-walled sacs, walls made of single layer of Type 1 alveolar cells
2) A network of pulmonary capillaries with one-cell thickness
3) Interstitial space between alveolus and capillary
4) Alveolar-capillary membrane

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37
Q

Type 1 alveolar cells make up what?

A

Thin-walled sacs of the alveoli clusters

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38
Q

Lungs have ______________ alveoli each about _____________ in diameter

A

500 million; 2-300um

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39
Q

What are the two factors that contribute to alveoli cluster surface area?

A

1) Lungs have 500 million alveoli each about 2-300um diameter
2) Pulmonary capillaries are extremely dense, essentially a continuous sheet of blood

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40
Q

List the jobs of type I and type II alveolar cells

A

1) Type I: make up thin-walled sacs of the alveoli clusters
2) Type II: secrete pulmonary surfactant

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41
Q

1) What do Type II alveolar cells do?
2) What permits airflow between adjacent alveoli?

A

1) Secrete pulmonary surfactant
2) Pores of Kohn exist in walls between adjacent alveoli, permitting airflow
-Redundancy allows fresh air to alveoli that may otherwise be blocked

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42
Q

Where are the Pores of Kohn and what do they do?

A

Exist in walls between adjacent alveoli, permitting airflow
-Redundancy allows fresh air to alveoli that may otherwise be blocked

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43
Q

1) How many alveoli are present at birth, and what is their surface area in m^2? Compare to skin surface area in m^2.
2) What about at 8 years old?
3) As an adult?
*don’t need to know exact numbers, just get general trend

A

1) 24 at birth; 2.8
-0.2 of skin
2) 300 at 8; 32
-.9 of skin
3) 300 as an adult; 75
-1.8 of skin

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44
Q

What are the 4 main groups of respiratory muscles? What do they do?

A

1) Diaphragm
2) Intercostals muscles
3) Scalene muscles
4) Sternocleidomastoids
-Aid in breathing/ pulmonary pressures

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45
Q

What is the main muscle of breathing and what innervates it?

A

1) Diaphragm
2) Phrenic nerve

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46
Q

An increase in volume in the lungs __[increases/ decreases___ the pressure

A

decreases

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47
Q

If there’s negative pressure in the lungs, what happens? Is this an active or passive process?

A

Air goes in; active process

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48
Q

Is exhalation an active or passive process?

A

Passive (usually)

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49
Q

What is Dalton’s law?

A

Total barometric pressure (PB) is equal to the sum of the partial pressures of the individual gasses.

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50
Q

List 4 individual gasses that contribute to total barometric pressure?

A

Nitrogen (N)
Oxygen (O)
Water vapor (H2O)
Carbon dioxide (CO2)

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51
Q

How do you calculate PB (total barometric pressure)

A

PB=PN2+PO2+PH2O+PCO2

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52
Q

Give an example of how to calculate partial pressure from PB (total barometric pressure)

A

Partial Pressure of Oxygen: 160mmHg
Barometric pressure: 760
PO2: (760 x 0.21) =160

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53
Q

What is Boyle’s law?

A

Pressure exerted by a gas is inversely proportional to the volume it occupies.
-I.e. as volume increases, the pressure of the gas decreases (and vice versa)

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54
Q

A change in _____________ pressure is critical for lung _________ and deflation.

A

pleural; inflation and deflation

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55
Q

1) What is the pleural sac?
2) What makes up its interior?
3) What is secreted into its interior? Why?

A

1) Double-walled sac that separates each lung from thoracic wall
2) Pleural cavity
3) Intrapleural fluid is secreted to lubricate the surfaces as they slide during respiration

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56
Q

What are the 3 main types of pressure?

A

1) Alveolar Pressure (Pa)
2) Pleural Pressure (PPL)
3) Transmural pressure (Ptm) or Transpulmonary Pressure (PL)

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57
Q

1) Define alveolar pressure (Pa)
2) What is the point of all of the pressures of the thoracic cavity?
3) Define pleural pressure

A

1) Pressure inside alveoli
2) Prevent lung and airway collapse
3) Pressure surrounding lungs

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58
Q

Define transmural pressure (Ptm) or transpulmonary pressure (PL)

A

Pressure difference across the lung
-Difference of Pa and PPL

59
Q

The difference between Pa and PPL (i.e. Pa-PPL) is what?

A

Transmural pressure (Ptm) or Transpulmonary Pressure (PL)

60
Q

1) What is the transmural pressure gradient?
2) Give an example

A

1) Pressure gradient across lung wall, holds lungs and thoracic wall in close position
2) Atmospheric/alveolar pressure = 760mmHg
Intrapleural pressure = 756mmHg
-This means air pushing out against lung wall is greater than air pushing in

61
Q

1) Air moves _______a pressure gradient from _________ to __________ pressure.
2) What moves air into and out of lungs?

A

1) down; high to low
2) Cyclic respiratory muscle activity

62
Q

What are the 3 key pressures of respiratory mechanics? Define and describe each

A

1) Atmospheric (barometric) pressure: Pressure exerted by weight of the air in atmosphere
2) Intra-alveolar pressure: Alveoli communicate with airways, if there is a difference, pressure quickly equilibrates
3) Intrapleural pressure: Pressure in pleural sac, normally slightly lower than atmospheric pressure
-Closed sac, air does not equilibrate despite pressure gradient

63
Q

True or false: Intra-alveolar pressure quickly equilibrates if there’s a difference, whereas intrapleural pressure never reaches equilibrium

A

True

64
Q

1) Air does not normally enter where?
2) What happens if the thorax is punctured (stab wound, rib fracture, disease, etc)?
3) What is it called when this happens?
4) What does this lead to?

A

1) Pleural cavity
2) Air flows down pressure gradient into [pleural] cavity
3) Pneumothorax (air in chest)
4) Intrapleural and intra-alveolar pressure equilibrate
-Transmural pressure gradient no longer exists
-Lung collapses

65
Q

Intrapleural and intra-alveolar pressure equilibrate when?

A

When there’s a pneumothorax

66
Q

Air flows down pressure gradients, so intra-alveolar pressure must be ________ than atmospheric pressure during inspiration and __________ during expiration

A

less; greater

67
Q

Altering what changes intra-alveolar pressure?

A

Lung volume

68
Q

1) What accomplishes inspiration?
2) What does contraction do during inspiration?

A

1) Inspiratory muscles: diaphragm and external intercostal muscles
2) Enlarges thoracic cavity

69
Q

The diaphragm does what when contracted? What is this responsible for?

A

Descends down; 75% of the cavity enlargement

70
Q

1) Where are the external intercostal fibers?
2) What innervates these fibers?
3) What does their contraction do?

A

1) Fibers run down and in front of ribs
2) Intercostal nerves
3) Ribs and sternum elevate when external intercostals contract

71
Q

Deeper inspirations accomplished how?

A

By adding accessory muscle recruitment to diaphragm/external intercostal activity

72
Q

What do the accessory muscles do?

A

Raise sternum and elevate first two ribs, which enlarges upper thoracic cavity

73
Q

During expiration:
1) What do the inspiratory muscles do?
2) What do the diaphragm and ribs do?
3) What do the lungs do?
4) What happens to intra-alveolar pressure?

A

1) Relax
2) Assumes original dome shape, rib cage falls
3) Recoil to pre-inspiratory size
3) Rises

74
Q

1) What happens as a result of intra-alveolar pressure rising during expiration?
2) Where does air go?

A

1) Air molecules present at end of inspiration compressed into smaller volume
2) Travels down pressure gradient out of the lungs until pressure equilibrates

75
Q

1) What does most of the work for airflow?
2) Which muscles can stop working without losing the ability to breathe? Which can’t?
3) What does the phrenic nerve arise from?

A

1) Contraction and relaxation of the diaphragm does
2) Can still breathe if intercostal muscles disrupted but dangerous if diaphragm is disrupted
3) C3, C4, C5

76
Q

True or false: Inspiration is always an active process because it involves muscle contraction

A

True

77
Q

Expiration can be __________ (lung recoil) or __________ (forced expiration)

A

passive; active

78
Q

1) What does active/ forced expiration do differently from passive expiration?
2) What is required of intra-alveolar pressure during active expiration?

A

1) Empties lungs more completely and more rapidly
2) Intra-alveolar pressure must increase further than in normal expiration

79
Q

1) What do the expiratory muscles do during forced/ active expiration?
2) What muscles in this group are most important during forced expiration? What do these do?
3) What other muscles are important and what do they do?

A

1) Contract to further reduce thoracic volume
2) Abdominal muscles; contract to increase intra-abdominal pressure which pushes up on diagram
3) Internal intercostals which contract to pull ribs down and flatten chest wall

80
Q

1) Define spirometer
2) What does it display?
3) What units are used?

A

1) Test to measure how much volume and how fast you can move air in/out
2) Displays and volume-time curve on a spirogram
3) Volume (L) and time (seconds)

81
Q

1) Maximum lung capacity _________________mL depending on wide variety of factors
2) Minimum can go as low as __________________mL
3) There’s about a __________________ml difference with each breath

A

1) 4200-5700ml
2) 1000-1200ml
3) 500ml difference with each breath

82
Q

True or false: Gas exchange can continue to occur with air in alveoli and O2 and CO2 exchange prevented from fluctuating wildly breath to breath

A

True

83
Q

1) Lung volume changes can be measured with what?
2) Breathing into air filled drum in a sealed chamber, what two things can be measured?

A

1) Spirometry
2) [Air] rise and fall can be measured

84
Q

1) Define tidal volume (TV)
2) Define inspiratory reserve volume (IRV)
3) Define inspiratory capacity (IC) and its components

A

1) TV: Air exchanged during single breath (^500mL)
2) IRV: Extra volume that can be inspired above tidal volume (3000mL)
3) IC: Maximum amount of air that can be inspired after normal expiration (IRV + TV)

85
Q

1) Define expiratory reserve volume (ERV)
2) Define residual volume (RV)
3) Define functional residual capacity (FRC) and its components

A

1) ERV: extra volume that can be expired after normal expiration (1000mL)
2) RV: minimum air remaining after maximum expiration (1200mL)
3) FRC: Volume of air remaining after normal expiration (ERV + RV)

86
Q

1) Define vital capacity (VC) and its components
2) Define total lung capacity (TC) and its components

A

1) Maximum amount of air that can be expired after maximal inspiration (IRV + TV + ERV)
2) Maximum volume that lungs can hold (VC + RV)

87
Q

What is FEV1?
What is it usually?
Explain what it indicates

A

1) Forced expiratory volume in 1 second (FEV1) volume of air that can be expired in 1 second
2) Usually 80% of VC.
3) Indicates maximal airflow rate.

88
Q

True or false: Residual lung volume cannot be measure directly by spirometry

A

True

89
Q

1) How is residual lung volume measured?
2) Explain how this is done

A

1) Indirectly using helium
2) Patient breathes/rebreathes the helium-oxygen mixture

90
Q

1) What is average minute ventilation?
2) Is this the same as alveolar ventilation? Explain

A

1) 500mL x 14 (per min RR) = 7L/min
2) No; not all of the inspired air reaches the alveoli, it becomes dead space

91
Q

When can dead space occur?

A

1) Normal amount of dead space due to not all average minute ventilation reaching alveoli
2) If there’s not enough circulation:
-A: No blood flow
-B: Reduced blood flow

92
Q

1) What is the formula for pulmonary ventilation? Give the average
2) Does all the air participate in gas exchange? Explain

A

1) Tidal volume X respiratory rate
500 x 12 = 6,000mL air per minute
2) Not all of the air participates in gas exchange, some remains in the airways (150mL). This volume is called the anatomic dead space.
-During expiration, some of the air remains in the airways
-Thus, during the next inspiration, some of the air has already undergone gas exchange

93
Q

Even though _____mL inspired, only ______mL undergoes gas exchange in alveoli, _______mL remains in airway

A

500ml inspired; 350ml undergoes gas exchange; 150ml remains

94
Q

During expiration, some of the air remains in the airways. What does this imply?

A

During the next inspiration, some of the air has already undergone gas exchange

95
Q

1) What is the formula for alveolar ventilation? What is the average?
2) Is it more or less important than pulmonary ventilation in determining gas exchange?

A

1) (Tidal volume – dead space volume) X respiratory rate
Average 4200mL/min
2) More important

96
Q

If a person breathes deeply (tidal volume 1200) and slowly (5/min), what happens to pulmonary ventilation and alveolar ventilation?

A

Pulmonary ventilation is 6000mL/min but alveolar ventilation is 5250mL/min

97
Q

If a person breathes shallowly (tidal volume: 150mL, 40/min), what would be the pulmonary ventilation and alveolar ventilation?

A

Pulmonary ventilation 6000mL/min, alveolar ventilation is zero

98
Q

When increased ventilation is required, which is more important: depth of breathing, or rate of breathing?

A

Depth of breathing

99
Q

1) Define hypoventilation
2) Define hyperventilation

A

1) Hypoventilation: Decrease in alveolar ventilation
2) Hyperventilation: Increase in ventilation causes a fall in blood PaCO2

100
Q

List and describe the 3 basic components of the lung’s elastic properties

A

1) Elastic Recoil: Ability to return to rest after stretch
2) Stiffness: Resistance to stretch; collagen fibers
3) Distensibility: Ease with stretch; elastin fibers

101
Q

1) Which causes a fall in blood PaCO2, hyperventilation or hypoventilation?
2) What components of elasticity do elastin and collagen each give the lungs?
3) What property of lungs can pulmonary fibrosis alter?

A

1) Hyperventilation
2) Elastin gives distensibility, collagen gives stiffness
3) Compliance

102
Q

1) What does a highly compliant lung do? Why?
2) What property does lung compliance measure?
3) What can decrease compliance?

A

1) Stretches further for given change in pressure
2) Distensibility
3) Can be decreased by many factors, like pulmonary fibrosis where fibrous connective tissue relaces normal long tissue due to breathing asbestos or other irritants

103
Q

What affects elastic recoil of the lungs? Define this.

A

Alveolar surface tension: more attraction between water-molecules than to air above the surface

104
Q

What 3 things affect lung compliance?

A

Lung volume
Lung size
Surface tension inside the alveoli

105
Q

1) What does restrictive lung disease do to compliance? Explain
2) What does COPD do to compliance? Explain

A

1) Low lung compliance; stiff
2) High lung compliance; overstretched with low elastic recoil

106
Q

1) What is the 6th leading cause of death?
2) What is this condition?
3) What does it cause?
4) Give 3 examples of this category

A

1) Chronic obstructive pulmonary disease (COPD)
2) Group of lung diseases characterized by increased airway resistance
3) Larger pressure gradient needed for normal airflow rate
4) Chronic bronchitis, asthma, and emphysema

107
Q

1) What is chronic bronchitis and what is it caused by?
2) What can it cause?

A

1) Long-term inflammation of lower airways from smoking, pollution, allergens
2) Prolonged thickening of airways, mucus overproduction, frequent infections

108
Q

What is asthma? What does it cause?

A

Obstruction from thickening from histamine-induced edema, excess mucus secretion, and airway hyperresponsiveness (triggers cause profound constriction)

109
Q

1) What is emphysema? What usually causes it?
2) What is it less often from?

A

1) Alveolar destruction [‘grapes’ pop], usually from chronic exposure to cigarette smoke and other irritants.
2) Less frequently from genetic lack of protective enzyme

110
Q

1) What can happen to someone with COPD during normal expiration?
2) What happens because of that?
3) What is the unique, visible, more long-term change that results from this?

A

1) Smaller airways can collapse during routine expiration
2) Air trapped in the alveoli behind the collapsed smaller airways cannot exchange with atmosphere
3) Extra-trapped air = enlarged lungs = barrel chested
(But still less gas exchange due to alveolar destruction esp. with emphysema)

111
Q

Why is there still less gas exchange when the lungs are enlarged due to extra trapped air from a COPD?

A

Alveolar destruction (esp. with emphysema)

112
Q

1) Surface tension of pure water is countered by what?
2) What makes up this substance?

A

1) Pulmonary surfactant
2) Mix of lipids and proteins secreted by Type II alveolar cells

113
Q

What does pulmonary surfactant do? (3 things)

A

1) Intersperses water molecules and lower alveolar surface tension
2) Increases pulmonary compliance and reduces recoil
3) Stabilizes alveoli

114
Q

What would happen if the alveoli were lined with water alone?

A

Cohesive forces between water molecules is so strong; the surface tension would be so great that lungs would collapse

115
Q

1) What causes newborn respiratory distress syndrome?
2) What does this cause?
3) How is it treated?

A

1) the fact that pulmonary surfactant is synthesized in late pregnancy
2) Premature infants may not produce enough pulmonary surfactant, requiring large amount of effort to overcome surface tension
3) With surfactant replacement until secreting cells mature

116
Q

1) What is the primary determinant of resistance?
2) What else contributes to resistance?
3) Major sites of airway resistance for decreasing airflow are what?

A

1) Airway radius
2) Autonomic regulation (both sympathetic and parasympathetic)
3) The bronchi

117
Q

Describe the two parts of autonomic regulation of airway resistance

A

1) Parasympathetic = bronchoconstriction = increased resistance
2) Sympathetic = bronchodilation = decreased resistance

118
Q

1) When can resistance become extremely important? Give examples
2) What don’t smaller airways have that larger airways do?

A

1) When lumens are abnormally narrowed
-Disease, smoking, congestion, mucus accumulation
COPD
2) Don’t have cartilage rings holding them open

119
Q

What is the implication of smaller bronchioles not having cartilage holding them open?

A

Thoracic expansion dilates them, this means resistance during inspiration is lower than expiration
Small difference doesn’t matter in healthy individuals
Expiratory increased resistance can be noticeable in COPD

120
Q

What thing affects airway patency? What can alter this? Give examples

A

1) Affected by changes in smooth muscle tone
2) Parasympathetic/sympathetic and drugs:
-Isoproterenol and epinephrine stimulate B2 adrenergic receptors causing dilation

121
Q

1) Gas Exchange is closely linked to what?
2) During gas exchange, what two things move across by diffusion?
3) Why do these things diffuse?

A

1) Pulmonary circulation
2) Oxygen and Carbon Dioxide
3) Due to the partial pressure gradients of the individual gases

122
Q

1) ________________ and ______________ stimulate B2 adrenergic receptors, causing dilation
2) Higher altitude leads to what?

A

1) Isoproterenol and epinephrine
2) Lower gas exchange of O2 due to lower amount pressure in the atmosphere

123
Q

What is Fick’s law? (2 parts)

A

1) Rate of gas diffusion is inversely related to membrane thickness
2) And directly proportional to surface area

124
Q

What is the major determinant in transferring oxygen from the alveoli to the blood?

A

Pulmonary capillary blood flow

125
Q

1) How is most O2 transported? What percent?
2) How is the rest of the O2 transported?

A

1) While chemically bound to hemoglobin (oxyhemoglobin); 98.5%.
2) 1.5% physically dissolved in blood

126
Q

1) What is the main factor of Hgb (hemoglobin) saturation? Does Hgb-bound oxygen directly contribute to this?
2) What percent of CO2 is bound to Hbg? How is the rest transported?

A

1) The partial gradient; Hgb-bound O2 does not contribute (directly) to partial gradient
2) 30% bound to Hgb, 60% as bicarb, 10% dissolved

127
Q

1) What is %Hgb saturation?
2) What is law of mass action?

A

1) Measure of extent to which Hgb is combined with O2
2) If the concentration of one substance in a reversible action is decreased, the reaction is driven in the opposite direction

128
Q

What happens because of the law of mass action? (2 things)

A

1) If surrounding blood is low in O2, oxyhemoglobin will dissociate into hemoglobin and oxygen (releasing O2 for local utilization)
2) If surrounding blood is high in O2 it will combine with hemoglobin into oxyhemoglobin (like in pulmonary capillaries)

129
Q

1) The relationship between partial gradient of O2 and Hgb saturation is called what?
2) What are its two portions? What occurs during each?

A

1) The O2-Hgb dissociation (or saturation) curve
2) Plateau portion: O2 loaded onto Hgb at pulmonary capillaries
Steep portion: O2 unloaded at systemic capillaries

130
Q

Name 4 other factors that can affect Hgb saturation

A

1) CO2
2) Acidity
3) Temperature
4) 2,3-bisphosphoglycerate

131
Q

1) How can CO2 affect Hgb saturation?
2) How can acidity affect Hgb saturation?

A

1) More CO2 further decreases affinity of Hgb for O2 so that it unloads O2 even more rapidly near tissues high in CO2
2) Reduces affinity for O2 as blood becomes more acidic (usually from carbonic acid from CO2), delivering more O2 to metabolically active tissue

132
Q

1) How can temperature affect Hgb saturation?
2) What is 2,3-bisphosphoglycerate? How does it affect Hgb concentration?
3) When does 2,3-bisphosphoglycerate (BPG) increase?

A

1) Heat enhances O2 release from Hgb. Active tissue generates more heat.
2) Erythrocyte constitution that reversibly binds to Hgb, reducing O2 affinity.
3) When Hgb is chronically undersaturated (like in high altitudes)

133
Q

1) Carbon monoxide and oxygen compete for same binding sites on Hgb, but affinity for _______ is 240 times higher.
2) How is bicarb (HCO3) created in the blood?

A

1) CO
2) CO2 first combines with water to form carbonic acid then spontaneously dissociates into H and HCO3

134
Q

1) When Hgb is chronically undersaturated (like in high altitudes), what increases?
2) Presence of CO does what to O2?
3) What is a odorless, colorless, tasteless, nonirritant gas that can be lethal before victim is aware of danger?

A

1) BPG (2,3-bisphosphoglycerate) production
2) Makes Hgb unavailable for O2
3) CO

135
Q

True or false: CO2 can dissolve into blood or bind to Hgb but most of it is transported as bicarb (HCO3)

A

True

136
Q

1) Define hypoxia
2) Define hypoxic hypoxia. What can cause it?

A

1) Insufficient O2 at the cellular level
2) Decreased partial gradient; respiratory malfunction or high-altitude/suffocating environment

137
Q

1) What is anemic hypoxia?
2) What can cause it?
3) What type of hypoxia can result from vascular blockage, shock, heart failure?

A

1) Decreased carrying capacity
2) Decreased RBCs, decreased Hgb, carbon monoxide poisoning
3) Circulatory hypoxia

138
Q

1) What is circulatory hypoxia? What can cause it?
2) What is histotoxic hypoxia? What can cause it?

A

1) Decreased delivery; vascular blockage, shock, heart failure
2) Delivery is normal, but cells cannot use O2. Cyanide poisoning: blocks cellular respiration

139
Q

1) Does hyperoxia occur spontaneously?
2) What usually causes it?
3) Is this a good thing or a bad thing? Explain.

A

1) No; does not occur when breathing atmospheric air at sea level
2) Usually from breathing supplemental O2, increasing partial gradient
3) Not advantageous, can cause oxygen toxicity, brain damage, and blindness

140
Q

List 2 CO2 abnormalities

A

Hypocapnia and hypercapnia

141
Q

List the 4 types of hypoxia

A

1) Hypoxic hypoxia
2) Anemic hypoxia
3) Circulatory hypoxia
4) Histotoxic hypoxia

142
Q

1) What is hypocapnia?
2) What causes it?
3) What is occurring in the body?
4) What is it important to differentiate from?

A

1) Below normal arterial CO2
2) Hyperventilation
3) Rate of CO2 removal exceeds metabolic need
4) Not the same as increased ventilation (hyperpnea) as during exercise in which case arterial O2 and CO2 remain constant

143
Q

1) What is hypercapnia?
2) What can cause it?
3) What is occurring in the body?

A

1) Excess CO2 in arterial blood
2) Hypoventilation
3) Ventilation inadequate to meet metabolic needs for O2 delivery and CO2 removal

(PA school) Human Physiology (35 decks)

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