Transcript The Respiratory System

The Respiratory System
How it contributes to homeostasis.
Why do we breathe?
Structures.
Anatomical changes.
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Alveolar-Capillary Membrane
300-600 million alveoli

Type I and Type II alveolar cells

Macrophages

Respiratory Membrane
1)
2)
3)
4)
Type I and II-alveolar wall
Epithelial basement membrane
Capillary basement membrane
Capillary endothelium
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Do not confuse the two terms: Respiration and Ventilation
What is Respiration?
What is Ventilation?
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Pulmonary Ventilation
Inspiration / Inhalation
Normal (quiet) = diaphragm and external intercostals
Forced (deep) = scalenes, sternocleidomastoid, pectoralis minor
Expansion of thoracic cavity
Lung stretched, lung volume increases
Pressure gradient
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Pulmonary Ventilation
Expiration / Exhalation
Normal (quiet) = diaphragm and internal intercostals
Forced (deep) = abdominal obliques and transverse
Relaxation and Retraction of thoracic cavity –
-Elastic recoil
Lung volume decreases
Pressure gradient
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Pulmonary Ventilation
Surface tension


Alveolar fluid
Surfactant
Compliance


HighLow-
Airway resistance


Bronchioconstriction
Bronchiodilation
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External Respiration
Gas Laws
Dalton’s Law of partial pressures = Total pressure exerted by a mixture of
gases is the sum of the pressures exerted independently by each gas in the
mixture.
Partial pressure of oxygen – PO2
Air Pressure
.
**Goal**
Oxygen uptake,
Carbon Dioxide
unloading
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External Respiration
Gas Laws
Henry’s Law of solubility = The quantity of a gas that will dissolve in a liquid is
proportional to the partial pressure of the gas and its solubility.
Much more CO2 is is dissolved in blood plasma because the solubility of CO2 is
24x greater than that of O2.
.
**Goal**
Oxygen uptake,
Carbon Dioxide
unloading
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Questions for you..
O2 diffuses rapidly from the alveoli into the blood. CO2 diffuses slower.
Why?
But wait!!
In our bodies, equal amounts must be exchanged. How does this
happen?
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Partial pressures of the gases determine their movements.
 If atmospheric high, pressure increased.
Ex. Scuba diving.
If atmospheric pressure is low, rate of flow into the blood/body is
decreased.
Ex. Altitude sickness; sob, dizziness.
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Internal Respiration
Tissue gas exchange

(aka-systemic gas
exchange)
Once inside the cell, the oxygen is used for aerobic respiration.
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Transport of oxygen and carbon dioxide
Oxygen
Hemoglobin (Hb)
Transported 2 ways.
Affinity
Carbon dioxide
Transported 3 ways.
Chloride shift
Animation??
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The rate of internal and external respiration is
determined by:
1. The partial pressures
2. The surface area
3. Solubility of the gasses
4. Diffusion distance
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Control of Respiration – Breathing Rhythm
Respiratory Center in brain stem
Medulla and Pons
Sends impulses along the
phrenic and intercostal nerves
Sets the eupnea
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Control of Respiration – Breathing Rate and Depth
Chemoreceptors
-- central
--peripheral
Uses chemoreceptors to detect fluctuations.
1. Acidosis (acidemia) = blood pH falls
below 7.35
2. Alkalosis = blood pH rises above 7.45
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Control of Respiration – Breathing Rate and Depth
Cortical influences
-- cerebral cortex
1. voluntary control
2. emotions
-hypothalamus
-lymbic system
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Control of Respiration – Breathing Rate and Depth
Proprioceptor stimulation

Detect movement of joints and muscles
Inflation reflex

Baroreceptors

More on table 22.2 in textbook
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Disorders
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Questions:
22.13 If the volume of the cylinder in Figure 22.12 decreased from 1 liter to ¼ liter,
how would the pressure change?
22.15 Would contraction of the external intercostals increase or decrease alveolar
pressure? Would it cause air to enter or leave the lungs? Would contraction of the
internal intercostals increase or decrease alveolar pressure? Would it cause air to
enter or leave the lungs?
22.18 Would airflow into alveoli be greater with higher or lower compliance of the
lungs? Larger or smaller bronchioles?
22.25 What are the diffusion paths of O2 and CO2 during external and internal
respiration?
22.26 What causes O2 to enter pulmonary capillaries from alveolar air and to enter
tissue cells from systemic capillaries?
22.27 Which factors affect the rates of diffusion of O2 and CO2?
22.35 Which nerves convey impulses from the respiratory center to the diaphragm?
22.40 Which chemicals stimulate peripheral chemoreceptors?
22.42 What happens to the rate and depth of breathing when the PCO2 becomes
elevated?
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