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Physiology > Chapter 11 (Respiration) > Flashcards

Chapter 11 (Respiration) Flashcards

1
Q

Internation Respiration/Cellular Respiration

A
  • Refers to the metabolic processes carried out within the mitochondria
    Respiratory Quotient (RQ)
  • Ratio of CO2 produced, to O2 consumed
  • Varies depending on nutrients consumed
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2
Q

External Respiration

A
  1. Ventilation between the atmosphere and air sacs (alveoli) in the lungs.
  2. Exchange of O2 and CO2 between air in the alveoli and the blood in the pulmonary capillaries
  3. Transport of O2 and CO2 by the blood between the lungs and the tissues
  4. Exchange of O2 and CO2 between the blood in the systemic capillaries and tissue cells.
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3
Q

Anatomy of the Respiratory System

A
  • Nasal passages
  • Pharynx: common passageway for food and air
  • Trachea
  • Larynx: voice box
  • Bronchi
  • Bronchioles
  • Pulmonary alveoli
  • Trachea and larger bronchi
  • Bronchioles
    a. no cartilage, walls contain smooth muscle innervated by ANS
    b. sensitive to certain hormones and local chemicals
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4
Q

Lungs

A
  1. Diaphragm
    - Dome shaped sheet of skeletal muscle
    - Separates thoracic cavity from the abdominal cavity
  2. Pleural Sac
    - Double-walled, closed sac that separates each lung from the thoracic cavity
    - Pleural Cavity - interior of plural sac
    - Intrapleural fluid
    a. secreted by surfaces of the pleura
    b. lubricates pleural surfaces
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5
Q

Conducting Zone

A
  • Trachea
  • Main bronchus
  • Bronchus
  • Bronchiole
  • Terminal Bronchiole
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6
Q

Respiratory Zone

A
  • Respiratory Bronchiole
  • Alveolar Duct
  • Alveolar Sac
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7
Q

Alveolus

A
  • Site of gas exchange
  • Walls consists of a single layer of flattened Type 1 alveolar cells
  • Pulmonary capillaries encircle each alveolus
  • Type 2 alveolar cells secrete pulmonary surfactant
  • Alveolar macrophages
  • Pores of Kohn
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8
Q

Boyle’s Law

A
  • With a constant temperature, the pressure and volume will fluctuate inversely. Pressure increases, volume decreases by the same factor.
  • If intra-alveolar pressure is less than atmospheric pressure, air enters the lungs. If the opposite occurs, air leaves the lungs.
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9
Q

Types of Pressure

A
  1. Atmospheric (barometric) pressure
  2. Intra-alveolar pressure (intrapulmonary)
  3. Intrapleural pressure (intrathoracic)
  4. Transmural pressure
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10
Q

Atmospheric Pressure

A

The pressure that is exerted by the weight of the air in the atmosphere.

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11
Q

Intra-alveolar Pressure

A

Pressure within the alveoli

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12
Q

Pleural Pressure

A

The pressure outside the lungs, but still within the thoracic cavity; pressure in the pleural space.
It closely approximates intrathoracic pressure.

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13
Q

Transmural Pressure Gradient

A

Always calculated as the inside pressure minus the outside pressure.
Alveolar pressure - Pleural pressure = Transpulmonary pressure

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14
Q

Breathing Mechanics

A

Muscles of Quiet Breathing

  1. The Diaphragm
  2. The external intercostal muscles

Muscles of Deeper Breathing

  1. The Diaphragm
  2. External intercostal muscles
  3. Accessory muscles of inspiration (sternocleidomastoid and scalenus)
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15
Q

Muscle Activity During Inspiration

A
  1. Contraction of external intercostal muscles causes the elevation of ribs which increases side-side dimension of the thoracic cavity
  2. Lowering of the diaphragm on contraction increases vertical dimension of the thoracic cavity.
  3. Elevation of ribs causes the sternum to move upwards and outward, which increases front-back dimensions of thoracic cavity.
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16
Q

Muscles of Expiration

A
  1. Internal Intercostal muscles
  2. Diaphragm
  3. Abdominal Muscles
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17
Q

Muscle Activity During Expiration

A
  1. Return of diaphragm, ribs, and sternum to resting position on relaxation of inspiratory muscles. Restores thoracic cavity to pre-inspiratory size.
  2. Contraction of internal intercostal muscles causes the flattening of the ribs and sternum, further reducing side-side and front-back dimension of thoracic cavity.
  3. Contraction of abdominal muscles causes the diaphragm to be pushes upwards, further reducing vertical dimension of the thoracic cavity.
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18
Q

Pressure Changes During Breathing

A
  1. Before inspiration, at the end of expiration:
    - Intra-alveolar pressure is equal to atmospheric, no air is flowing.
  2. Inspiration:
    - Lungs increase in volume, intra-alveolar pressure decreases. Outside > inside pressure allows air to flow into the alveoli.
  3. Expiration:
    - Lungs recoil to previous size, intra-alveolar pressure increases. Inside > outside pressure allows air to flow out of the alveoli.
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19
Q

Pressure Gradient and Resistance

A

F = change of P / R
F: Flow rate
P: Difference b/w atmospheric and intra-alveolar pressure
R: resistance of airways (related to radius)

  1. In a healthy person, the radius of the conducting system is large and resistance remains extremely low.
  2. In an asthmatic person, the radius can be low and resistance can be high, so less air moves into the lungs.
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20
Q

Role of ANS in Flowrate

A

Parasympathetic:

  • Promotes bronchiolar smooth muscle contraction
  • Bronchoconstriction. Increases air resistance.
  • Low air demand.

Sympathetic:

  • Your body secretes epinephrine to promotes smooth muscle relaxation
  • Bronchodilation. Decreases airway resistance
  • High air demand.
21
Q

Surface Tension

A

The attractive forces in water is responsible for surface tension. Because of this the alveoli

  1. Resists being stretched.
  2. Tends to be reduced in surface area or size.
  3. Tends to recoil after being stretched.
22
Q

Pulmonary Surfactant

A

Secreted by Type 2 Alveolar Cells

  1. Increases the surface tension and decreases pulmonary compliance; reduces inflation of the lungs.
  2. Reduces the lungs capacity to recoil, preventing them from collapsing.
  3. Maintains the lungs stability.
23
Q

Spirometer

A

Measures lung volume and capacity.

24
Q

Spirogram

A

A graph that record inspiration and expiration

25
Q

Lung Volumes and Capacities

A
  1. Tidal volume (TV): The volume of air entering and leaving the lungs in a single breath (~500ml)
  2. Inspiratory Reserve Volume (IRV): Extra volume of air that can be maximally inspired over and above the typical resting tidal volume (~3 L)
  3. Expiratory Reserve Volume (ERV): Extra volume that can be actively expired by maximal contraction beyond the normal volume of air after a resting tidal volume. (1 L)
  4. Residual volume (RV): the minimum volume of air remaining in the lungs even after a maximal expiration (~1.2 L)
  5. Vital Capacity (VC): the maximum volume of air that can be moved out in a single breath following a single breath following a maximal inspiration.
    VC = IRV + VT + ERV = 4500ml
  6. Total lung capacity: The maximum volume of air that the lungs can hold
  7. TLC: VC + RV (5,700ml)
26
Q

Pulmonary Ventilation

A

The volume of air breathing in and out in 1 minute.

  • Changes in lung volume are represented by:
    1. Minute/pulmonary ventialation
    2. Respiratory rate

Pulmonary/minute ventilation = tidal volume x respiratory rates

27
Q

Alveolar Volume/Ventilation

A

Volume of the air exchanged between the atmosphere ad the alveoli per minute.
(TV - Dead Space Volume) x Respiratory rate = Alveolar Ventilation

28
Q

Anatomic Dead Space

A

A portion of inspired air will remain in the conducting airways and is not available for gas exchange.
~ 150ml
- 500ml of old alveolar air is expired, only 350ml expired to atmosphere, 150ml remains in the dead space.
- 150ml of inspired air is old alveolar air that was in the dead space. A fresh 150ml will enter the dead space.

29
Q

Work of Breathing

A
  • Normally requires 3% of total energy expenditrue for quiet breathing
  • Lungs normally operate at about “half full”
  • Work of breathing increases when:
    1. Pulmonary compliance is decreased
    2. When airway resistance is increased
    3. When elastic recoil is decreased
    4. When there is a need for increased ventilation.
30
Q

Local Control of Smooth Muscles on the Airways

A
  1. Accumulation of carbon dioxide in alveoli decreases airway resistance leading to increased airflow
  2. Increase in alveolar oxygen concentration brings about pulmonary vasodilation which increases blood flow to match larger airflows.
31
Q

Partial Pressures

A
  • Individual pressure exerted independently by a particular gas among the mixture of other gases
  • The pressure exerted by a particular gas is directly proportional to the % of that gas in the total air mixture.
  • Partial pressure exerted by each gas in a mixture equals the total pressure times the fractional composition of this gas in the mixture.
  • The greater the partial pressure of a gas in a liquid, the more of that gas is dissolved in that fluid
  • Partial pressure gradient exists
    1. Between alveolar air and pulmonary capillary blood
    2. Between systemic blood and surrounding tissue
  • Gases always diffuse from the are of high partial pressure to lower.
  • The larger the partial pressure gradient, the more O2 and CO2 diffuses into and out of the tissue and blood.
    PO2= 21 x 760 / 100 = 159.6 mm Hg
32
Q

Pulmonary and Systemic Capillary Gas Exchang

A
  1. The venous blood, low in O2 and high in CO2, enters the lungs
  2. Alveolar O2 is high, and CO2 is low because only a portion of the alveolar air is replaced by fresh atmospheric air during each breath.
  3. The partial pressure gradients between the alveoli and pulmonary capillary blood cause O2 to diffuse into the blood, and CO2 out. This stops when partial pressures are equal.
  4. Blood leaving the lungs has a high partial pressure and O2 content, and low CO2 content.
  5. Partial pressure of O2 is higher, and CO2 is lower in O2 consuming and CO2 producing tissue cells.
  6. O2 diffuse from the arterial blood into cells, and CO2 from the cells to the blood.
  7. After the exchange, blood is low in O2 and high in CO2.
33
Q

Factors that Affects Gas Exchange

A
  1. An increase in surface area = increase in gas transfer.
  2. Increase in thickness of the barrier separating air and blood decreases the rate of gas transfer.
  3. Rate of gas exchange is directly proportional to the diffusion coefficient for a gas.
34
Q

Oxygen Transport

A
  1. Most oxygen in the blood is transported bound to RBC hemoglobin.
  2. O2 can be physically dissolved. 1.5% because O2 is a poor plasma soluble.
  3. Chemically bound to hemoglobin 98.5%.
    - Hb + O2 = HbO2 (oxyhemoglobin) - plasma
    - HbO2 = O2 + Hb (in the tissue)

The amount dissolved is directly proportional to the PO2 of the blood; the higher the PO2, the more O2 dissolved in the plasma.

35
Q

Gas Transport

A
  • The percent saturation is high where the partial pressure of O2 is high
  • The relationship is shown in the oxygen-hemoglobin dissociation curve.
  • The plateau part of the curve is where the partial pressure of oxygen is high
  • The steep part of the curve exists at the systemic capillaries.
36
Q

Haldane Effect

A

Hemoglobin promotes the net transfer of CO2 and H+ at both the alveolar and tissue levels.

  • H2CO3 in RBC’s dissociate into H2O and CO2
  • H2O then dissociates into H+
  • Unloading O2 allows Hb to pick up H+
  • Hb has a greater affinity for H+ than CO2.
37
Q

Bohr Effect

A

The decrease in the amount of oxygen associated with hemoglobin in response to a lowered blood pH (typically caused by increased CO2 concentration).

Both the Bohr and Haldene effect work together to facilitate O2 liberation and the collection of CO2 and CO2 generated H+

38
Q

CO2 Transportation in the Blood

A
  1. Physically dissolved 5-10%
  2. Bound to hemoglobin 5-10%
    - CO2 + Hb = HBCO2 (carbamino hemoglobin)
    - CO2 binds with globulin of Hb
  3. As bicarbonate ion 80-90%
    - CO2 + H2O = H2CO3 (carbonic acid)
    - H2CO3 = H+ + HCO3 (bicarbonate)
    - H+ + HCO3 = H20 + CO2 (blood)
39
Q

Hypoxia

A
  • Having insufficient O2 at the cell level
    1. Hypoxic hypoxia (high altitudes)
    2. Anemic hypoxia: related to reduced O2 capacity of the blood
    3. Circulatory hypoxia: related to too little blood delivery to the tissue (heart failures)
    4. Histotoxic hypoxia: the cells can’t use the O2 provided.
40
Q

Hyperoxia

A
  • Condition of having an above-normal arterial PO2

1. Can only occur when breathing supplemental O2

41
Q

Hypercapnia

A
  • Condition of having excess CO2 in arterial blood

1. Caused by hypoventilation

42
Q

Hypocapnia

A
  • Below normal arterial PCO2 levels
    1. Caused by hyperventilation
  • Can be caused by anxiety, ever or aspirin poisoning.
43
Q

Medullary Respiratory Centre

A
  1. Dorsal respiratory group - mostly inspiratory neurons.
    - On = inspiration
    - Off = expiration
  2. Ventral respiratory group - both inspiratory and expiratory neurons
    - Only activates during increased ventilation (exercise)
  3. Pre-botzinger complex - widely believed to generate respiratory rhythm.
44
Q

Pneumotaxic Centre

A

Pons

  • Sends impulses to DRG to help “switch off” inspiratory neurons
  • Dominates of apneustic centre
45
Q

Apneustic Centre

A

Pons

  • Prevents inspiratory neurons from being switched off
  • Provides an extra boost to inspiratory drive
46
Q

Hering-Breuer reflex

A
  • Triggered to prevent overinflation of the lungs
  • Chemical factors that play a role in determining magnitude of ventilation
  • PO2
  • PCO2
  • H+
47
Q

Ventilation Factors Unrelated to Gas Exchange

A
  • Sneezing and coughing
  • Noxious agents that cause you to stop breathing
  • Pain
  • Various emotional states
  • Swallowing
48
Q

Hearing-Breuer Reflex

A
  • Exercise causes high tidal volume
  • Pulmonary stretch receptors intiate the H-B reflex (medullary centre).
  • This prevents the lungs from over inflation by inhibiting the inspiratory neurons.

Physiology (13 decks)

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