Transcript document
The Respiratory System
Pulmonary Anatomy and
Physiology
Chapter 15: 393-423
What is Respiration?
Closely Matched to Activity
Includes:
Breathing:
Moving air into lungs
Gas Exchange: Between lungs and
blood
Gas Transport: By the blood
Gas Exchange: Between blood and
tissues
Cellular Respiration: O2 use
Pulmonary Overview:
Structure and Function
Mechanics of Breathing
Lung
Volumes and Capacities
Gas Exchange
Gas Laws: Partial Pressures
O2, CO2, and pH Homeostasis
Control of Ventilation
Special Issues: Exercise/Disease
The Lungs and
Homeostasis!
The primary effector in Maintaining
constant blood gases:
O2
CO2
pH (H+ and HCO3-)
You Guessed it! Exercise causes a
blood gas homeostatic
emergency!
Pulmonary Anatomy
Upper Respiratory Tract:
Nose,
Nasal Cavity,Pharynx etc.
Lower Respiratory Tract:
Larynx,
Trachea, Bronchi
Lungs
Pleural Membrane
Circulation and Lymphatics
Structure and Function:
Ventilation: Breathing –
airways/respiratory muscles
Gas Exchange: Interface
between air/blood
Alveoli
Pulmonary
capillaries
VERY thin diffusion distance
VERY great surface area
Assignment:
Read pages 393-406
Note: How do pressure
gradients affect breathing (page
402-403)
What is surfactant?
What is a “pneumothorax”?
Horace Pippin: “Cabin in the Cottonfields”
1930’s
Gases and Gases in
Solution
Oxygen is a gas!
Atmospheric Gases:
Concentrations:
Oxygen:
21%
Nitrogen: 78+%
Carbon Dioxide: 0.03%
Concentration vs. Partial
Pressure
Concentration (content) reflects
the relative amount of gas in a
gas mixture
Pressure: The force of
“bouncing” gas molecules
against the walls of any
container (lungs, atmosphere,
balloons)
Speaking of Balloons!
Let’s fill this
balloon with
expired air from
our lungs:
What are the
gases?
Put in the fridge
Pressure and Partial Pressure
Pressure: The force of ALL the
gas molecules as they “bounce
of the walls”
Partial Pressure: The force of
one particular TYPE of gas
molecule as they bounce…
In
this room: Partial Pressure
of guys vs. girls…
Gas Laws: The effect of T
and V on P…
What happens to molecular
movement when they heat up?
T =
P
What happens to the force
exerted against the walls, when
the walls close in?
V=
P
General Gas Law:
•PV = T
Or:
P = T/V
P = 1/V
P = T
Let’s check out the balloon…
Temperature and Volume
What happened
to the cooled
balloon?
Why “Hot Air
Balloons?
Hot air
molecules
“expand”…
Calculating Partial
Pressures
The atmospheric pressure at
sea level is 760 mm Hg:
21% of that pressure force is
from oxygen molecules:
760 mmHg X .21 = 160 mmHg
Pressure and Diffusion:
Gas Molecules move from
levels of high pressure to lower
pressure
PRESSURE GRADIENT
The pressure gradient of O2
between the alveoli and
pulmonary capillary DRIVE O2
into the blood
Oxygen “Gradients” in
the Lung:
105
Pulmonary
Capillary
40
= 40 mmHg
Alveolus
=
105 mmHg
When the blood
leaves the lung
=
105 mmHg
105
105
105
Gas Pressures: mmHg
Atm
PO2 160
PCO2
0.3
Alv
Deoxy
Blood
Oxy
Tissue
Blood Cells
105 40
105 40
40
40
45
45
Oxygen and Tissues
The relative
pressures of
CO2 and O2
drive oxygen
into the
tissues and
CO2into the
blood
Ventilation:
Inspiration: Breathing in
Diaphragm
contracts
Thorax Expands
Increased Volume = Decreased
Pressure compared to the air
Air Moves from high to low
pressures
Ventilation:
Expiration: Breathing out
Diaphragm
relaxes
Thorax recoils
Decreased Volume = Increased
Pressure compared to outside
air
Air moves out of the lungs
Surfactant:
Lungs Expand: Pleural
membranes pull lungs out
during inspiration
Alveoli Expand: Surfactant
coats the inner surface of the
alveoli, and reduces surface
tension –which keeps the
alveoli from collapsing during
exhalation
The Purpose of Ventilation:
To Get Oxygen from the
atmosphere to the needy
tissues
Gas enters the blood only
from the alveoli.
The remainder of the
respiratory tract is “Dead
Space”
Gas Exchange:
Efficiency Depends on:
Pressure
Gradients between
alveoli and capillary PO2
Solubility constant:(O2 is OK)
Diffusion Distance: 2 cells thick
Surface Area: All those alveoli
increase the surface area of the
lungs to 70 m2
The Hemoglobin Assist!
Hemoglobin in Red Blood
Cells increases the O2 carrying
capacity of the blood
Hemoglobin has a “heavy
attraction” (affinity) to oxygen
Hemoglobin carries ~98.5% of
the O2 in the blood
Hemoglobin-Oxygen
Dissociation Curve:
Carbon Dioxide:
Highest in the tissues
High solubility and diffusion
7% dissolved in plasma
23% combine with hemoglobin
70% combine with H2O
CO2 + H2O
H2CO3
Bicarbonate and pH
At physiologic conditions
(tissues):
H2CO3
+
H
+ HCO3
-
So CO2 causes a decrease in
pH
CARBONIC ANHYDRASE is
the enzyme catalyst
Breathing and pH
In the lung, the reaction
reverses:
H2CO3
H2O + CO2
So Exhaling blows off CO2 …
AND reduces H+
RESPIRATORY
COMPENSATION (of acidosis)
Assignment:
Read Pages: 406-410
Read Lab for Monday
Have a good weekend!