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A&P Winter > 23. Respiratory System > Flashcards

23. Respiratory System Flashcards

1
Q

Major Function of Respiratory System

A

supply the body with O2 and dispose of CO2

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2
Q

divide the respiratory system into: 2

A

Conducting Portion = from nostrils to bronchioles
- warm, moisten, cleanse (filter) incoming air

Respiratory Zone = respiratory bronchiole + alveolar duct + alveolar sac + alveolus

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3
Q

How many lobes in each lung

A

R lung has 3 lobes

L lung 2 lobes

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4
Q

Alveolii

A
  • simple squamous epithelial cells
  • Respiratory Membrane = Type I alveolar cell + Fused basement membrane + Endothelial cell of pulmonary capillary
  • Gas exchange occurs across the respiratory membrane:
  • alveolar cells secrete alveolar fluid (keeps surfaces moist + contains surfactant )
  • Phagocytic alveolar macrophages wander the inner alveolar surfaces to remove dust and other foreign particles
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5
Q

Surfactant

A
  • acts to decrease surface tension and prevents collapse of alveolus when exhale
  • surface tension opposes expansion of water surface
  • need to overcome surface tension to expand lungs
  • surfactant decreases surface tension by disrupting hydrogen bonds among water molecules making it is easier to expand the lungs
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6
Q

Atmospheric Pressure
Intrapleural Pressure
Alveolar (Intrapulmonic) Pressure

A

Atmospheric Pressure
• Pressure exerted by air (gases) on the surface of the body (at sea level = 760 mmHg)

Intrapleural Pressure
• Pressure within the pleural cavity (between the pleurae) and is normally about 4 mmHg less than atmospheric pressure (approx. 756 mmHg)

Alveolar (Intrapulmonic) Pressure
• Air pressure within the alveoli (changes with the phases of breathing)

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7
Q

Boyle’s Gas Law

A
  • that under constant temperature, the pressure exerted by a gas varies inversely with volume
  • if ↑ volume, then ↓ pressure
  • if ↓ volume, then ↑ pressure
  • If compress a gas to ½ its original volume the pressure is increased 2x
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8
Q

Air is composed of a mixture of gases:

A

• Each individual gas in this mixture exerts its own pressure (partial pressure)

  1. 6% nitrogen (N2)
  2. 9% oxygen (O2)
  3. 04% carbon dioxide (CO2) 0.06% other gases
  4. 40% water vapor = 100% Total
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9
Q

Dalton’s Law

A

• that atmospheric pressure is equal to the sum of the pressure exerted by each individual gas

pN2 + pO2 + pCO2 + pH2O + p(other gases) = atmospheric pressure

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10
Q

Respiratory Physiology involves 4 events:

A
  1. Pulmonary Ventilation
  2. External (Pulmonary) Respiration
  3. Internal (Tissue) Respiration
  4. Transport of Respiratory Gases: Oxygen
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11
Q
  1. Pulmonary Ventilation
A

• gas exchange between atmospheric air and the alveoli of the lungs

At Rest:

  • before inspiration, alveolar p = atmospheric p (760 mmHg)
  • diaphragm is relaxed (dome-shaped)

Inspiration –
- diaphragm and external intercostals contract
thoracic cavity increases in size
- lungs expand
- pressure in lungs decreases from 760 to 758 mmHg

Expiration –

  • diaphragm and external intercostals relax
  • thoracic cavity decreases in size
  • lungs recoil
  • pressure in lungs increases from 760 to 762 mmHg
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12
Q
  1. External (Pulmonary) Respiration
A

• gas exchange between the alveoli and blood in the pulmonary capillaries
• O2 and CO2 diffuse down their pressure gradients
> Oxygen: alveolar (105 mmHg) → to the blood (40 mmHg)
> Carbon Dioxide: blood (45 mmHg) → to alveolar (40 mmHg)
• pO2 measurement – indicated amount of O2 dissolved in plasma NOT bound to Hb
• since O2 solubility is so low, we need an “extra” mechanism to transport O2 – role of hemoglobin

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13
Q

gas exchange is aided by: 3

A
  • thinness of respiratory membrane
  • extensive surface area of the alveoli
  • numerous small pulmonary capillaries
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14
Q

how much gas dissolves in plasma depends on:

A
  1. partial pressure of the gas in air

2. solubility of the gas in water (Henry’s law)

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15
Q
  1. Internal (Tissue) Respiration
A

• gas exchange between the blood in the systemic capillaries and tissue cells
• O2 and CO2 diffuse down their pressure gradients
> Oxygen: blood (100 mmHg) → to tissue (40 mmHg)
> Carbon Dioxide: tissue (45 mmHg) → to blood (40 mmHg)

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16
Q
  1. Transport of Respiratory Gases: Oxygen
A
  • 98% of O2 is transported bound to the iron in the heme group of hemoglobin
  • 2% transported dissolved in plasma
  • O2/heme binding reversible
  • if pO2 increase, more O2 binds to Hb
  • can reduce affinity of Hb for O2 to enhance offloading at the tissues, as the body O2 needs change
3 products of metabolism:
↑ p CO2
↑ [H+] which will ↓ pH
↑ Heat
All reduce affinity of Hb for O2
17
Q

What is the Bohr effect?

Why Bohr effect?

A

at any given pO2 value, Hb releases more O2 when pH decreases

Why Bohr effect?
• a decrease in pH means there is more H+
• H+ binds to amino acid in Hb that alters Hb structure and decreases its O2 carrying capacity
• drives O2 off Hb so more O2 available to tissues

18
Q
  1. Transport of Respiratory Gases: Carbon Dioxide
A
  • 70% of CO2 is transported as bicarbonate ions (HCO3-) in the blood plasma
  • 23% is transported by Hb (globin portion) in RBCs as carbaminohemoglobin
  • 7% is dissolved in the blood plasma
19
Q

The Respiratory Center can be divided into two principal areas:

A

1) the medullary respiratory center in the medulla oblongata
> dorsal respiratory group (DRG)
> ventral respiratory group (VRG)

2) the pontine respiratory group in the pons

20
Q

1) Medullary Respiratory Center

A

• Controls basic rhythm of breathing. nerve impulses generated in DRG
• DRG inactive = passive expiration
• VRG inactive = quiet breathing
• VRG activated = forceful breathing
• Pre-Bötzinger complex: in VRG, generation of rhythm of breathing
composed of pacemaker cells that provide input to the DRG, driving the rate at which the DRG
neurons fire action potentials

21
Q

2) Pontine Respiratory Group

A
  • neurons are active during both inhalation and exhalation
  • transmits nerve impulses to the DRG in the medulla
  • MODIFIES the basic rhythm of breathing
22
Q

Pre-Bötzinger complex

A
  • in VRG
  • generation of rhythm of breathing
  • composed of pacemaker cells that provide input to the DRG, driving the rate at which the DRG
  • neurons fire action potentials
23
Q

Factors that Influence Breathing Rate/Depth

A

1) Higher brain inputs (cerebral cortex – voluntary control holding your breath)
2) Pulmonary irritants (presence of dust, smoke)
3) Inflation (Hering-Breuer) reflex (keep lungs from over-inflating)
4) Proprioceptor stimulation (monitor movement of joints and muscles)
5) Chemical factors (chemoreceptors monitor levels of CO2, O2 and H+ and provide input to respiratory center)

24
Q

Homeostasis is Disrupted:

A

Homeostasis is Disrupted

Increased arterial pCO2 = Decreased pH in blood and CSF

Chemoreceptors Stimulated
stimulates
Medullary Respiratory center

Dorsal Respiratory Group

Inspiratory muscles

Increased respiratory rate (more CO2 expired)

Decreased arterial pCO2 = Increased pH of blood and CSF

Homeostasis is Restored

A&P Winter (10 decks)

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