topic 10 powerpoint 10.0 Flashcards
Two primary operating features of gas exchange
The respiratory medium refers to the air or water that is involved in the exchange of gases. The respiratory surface, on the other hand, is the wetted epithelium where gas exchange takes place. Ex: gil
What is the respiratory surface in mammals?
lungs
What is ventilation?
Ventilation refers to the flow of the respiratory medium (air or water) over the external side of the respiratory surface.
Ex: air moves into and out of the lungs
What is perfusion?
Perfusion refers to the flow of blood or other body fluids on the internal side of the respiratory surface.
Ex: movement of blood through the capillaries surrounding the alveoli in the lungs, where gas exchange occurs.
Optimal gas exchange depends on
-A large respiratory surface is a wetted epithelium where gas exchange takes place, thus larger area means more gas exchange
-simple diffusion, process gases move from high concentration areas to lower area, determined by SA available for exchange
In mammals, the lungs carry out what extra features to prevent drying of respiratory surface?
-lungs are invaginated, meaning they have pockets or folds. These pockets help to keep the lungs from drying out by minimizing the exposure of the respiratory surface to dry air. AKA prevent evaporation
-Lungs allow air to become saturated with
water before it reaches the respiratory surface
What are the two types of ventilation?
-positive pressure breathing(frog), the air is forced into the lungs by muscle contractions, air pressure inside is greater than outside
-negative pressure breathing(mammals), air is pulled into lungs by muscle contractions that expand lungs and lowering air pressure inside, air pressure inside is lower than outside
If you had a highly infectious disease, such
as Covid- 19, should you stay in a hospital room that has a positive pressure ventilation system or a negative pressure ventilation system?
A. Positive
B. Negative
negative pressure in the room
Air is being pulled into the room, so the Coronavirus is not being pushed out of
the room to infect others)
What if you had a severely compromised
immune system?
A. Positive
B. Negative
positive
The air pressure in the room is greater than that outside of it, so it
pushes potential infection agents or chemicals away from the patient.
Air flows from the room to the outside adjacent space, so germs from the
outside are not being pulled into the room
What are some characteristics of the Mammalian Respiratory System?
- airways connecting exterior to lungs, filter, moisten, and warm entering air
2.Contractions of the diaphragm and muscles between the ribs
ventilate the lungs - The volume of inhaled and exhaled air varies.
- The centers that control breathing are located in the brain stem(medulla oblongata)
Describe air passageway in lungs
1.nasal passages: chamber for air wash
2.pharynx(throat): connects nasal passages to mouth, expect air + food +liquid
3. epiglottis: closes larynx during swallowing
4.larynx(voice box)
5. trachea(windpipe): airway that connects the larynx to two bronchi that lead into the lungs
6. lungs: elastic organ that exchanges gases between internal and external air
7. bronchi are branched airways that become bronchioles, leading into alveoli surrounded by networks of blood capillaries
food travels down the __ not the ___
esophagus, trachea
intercostal muscle
skeletal muscle between ribs that contract to fill and empty lungs
diaphragm
muscle sheets between chest cavity and abdominal cavity that contracts to fill lungs
T/F Gas exchnage has a small area
false: Large area for gas exchange: 150 million alveoli, each
surround by a dense network of capillaries
Larynx, trachea and large bronch have what in common?
are non-muscular tubes; have rings of cartilage around them for support
What controls the diameter of the Small Bronchi and bronchiole?
smooth muscle cells
bronchi has what two features?
Ronchi have cilia and mucus-secreting cells. Mucus traps dust, pollen, bacteria; cilia move material up to the throat
Air is exhaled passively due to:
-relaxation of diaphram + intercostal muscle
-Elastic recoil of lungs (pleural membranes)
Explain mechanism of inhalation
diaphragm contracts downward
external intercostal muscle contract,increase volume lifting rib cage upward and outward-decrease pressure-
lung volume expands- draw air into lungs
Palv(lung pressure)< Patm
explain mechanism of exhalation
Exhalation during breathing or rest. Diaphragm and external intercostal muscles return to the resting positions. Rib cage moves down. decrease in volume-Lungs recoil passively-increase pressure- expel air
Palv(lung pressure) > Patm
pleura
double layer of epithelial tissue
that covers the lungs
Visceral: inner layer that’s attached to lung surface
Parietal: outer layer that attaches to surface of the chest cavity
liquid in between layers help to prevent friction and abrasion between the lungs and the chest wall.
negative pressure
refers to a situation in which an enclosed area has lower
pressure than the area around it
What keeps lungs in contact with chest wall?
negative pressure in intrapleural space, liquid in space between visceral and parietal in pleura
T/F Lungs are inelastic and stiff
false; that’s why there is a pleura, to prevent friction when lungs moved upward and downward
They are compliant (stretchy)
tidal volume
Amount of air moved in and out of lungs during an
inhalation and exhalation
vital capacity
total volume of air a person can inhale and exhale by
breathing as deeply as possible
residual volume
Air remaining in the lungs after as much air as possible is
exhaled
What is the ideal gas law?
PV=nRT
*air flows from areas of higher to lower pressure
What is Boyle law?
P1V1=P2V2 pressure of gas is inversely proportional to volume
What does it mean by “Pathways in and out of lungs offer low resistance to flow”?
The airways are designed to be wide and open, allowing for smooth and unobstructed airflow.
What is ventilation in mammals?
exchange of air between the atmosphere
and alveoli in the lungs
F= change in pressure/ R , how do we calculate change in pressure?
Palv- Patm
lungs, Palv is less than and greater than Patm
What do you think would happen…
When the pressure in the alveoli is less
than the atmospheric pressure?
Air flow into lungs (Inspiration)
When the pressure in the alveoli is greater than the
atmospheric pressure?
Air flows out of lungs (Expiration)
Why does the lung expand when the chest
cavity expands since they are not directly
attached?
negative pressure in the intrapleural space that keeps the lungs in contact with the chest wall
Ptp
Ptp: transpulmonary pressure: difference in pressure between the
inside and outside of lungs
Ptp= Palv-Pip
Palv: alveolar pressure: pressure in the alveoli
Pip: intra pleural pressure: pressure in the pleural space
According to Ptp= Palv-Pip, which is always positive and which is always negative? Which changes?
- transpulmonary pressure is always positive;
-intrapleural pressure is always negative,
-alveolar pressure moves from slightly positive to slightly negative as a person breathes
Relate inspiration to Ptp= Palv-Pip
Breathe in, chest wall expands, pip has negative pressure aka lowerring pressure
when pip is lower, ptp increases and expands lungs.
Palv- Patm
Palv is less than Patm, air rushes in
What happens between breathes (at the end of an expiration) in terms of
pressure?
End of expiration, no air flow palv=patm
lungs lways have air in them so, ptp is positive and pip is negative. This negative intra pleural pressure “holds” the lungs open and the chest wall in.
In between breaths, we can expect who two things to be a zero? And what to be negative?
Alv and patm, pip is negative(-4)
expansion of the chest wall (increase in volume) at the end of
inspiration, the Pip has gone
from -4 to -7
Two Determinants of lung compliance:
1.“Stretchability” of the lungs.
The greater the lung compliance, the easier it is to expand
the lungs at any given change in transpulmonary pressure.
2. Surface tension:
surfactant on alveolar cells forms layer of fluid over it to reduce surface tension, which increases lung compliance
What would happen if there was no surfactant?
The tendency of the water molecules to attract (and form
a droplet) can cause the alveoli to collapse, thus
producing a fluid filled alveoli with smaller volumes than
an air filled alveoli. (Surfactant prohibits this)
