physiology lecture 21
TRANSCRIPT
8/12/2019 Physiology Lecture 21
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Announcements
Popular Physiology Review - Immune
Thursda A ril 17
Posted on D2L
Replacement/Makeup Exam Selection now open
See top right of D2L course page
Can make choice until May 2
Announcements
Exam 3
'v w y x .
Mean = 76.5 ±12.6 SD
Highest grade was 100
Mode = 84
Median = 77.5
This is always the hardest exam of the semester. As a group, you did quite well.
Lecture 21
Tuesday, April 15
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Announcements
Announcements
http://www.pbs.org/your-inner-fish/watch/
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Physiology in the News
Google Doodle from April 11
It’s not every day that you wake up, turn on the laptop, and see chemical structures
in the doodle on the Google search landing page. Especially those of drugs isolated
or made from plants…
Yet today, the Google Doodle marks the 115th anniversary of the birth of “The
cortisone physostigmine
http://www.forbes.com/sites/davidkroll/2014/04/11/todays-google-doodle-honors-pioneering-medicinal-chemist/
Forgotten Genius,” synthetic medicinal chemist, Dr. Percy Julian. Treatments for
glaucoma and rheumatoid arthritis, as well as oral contraceptives and testosterone
gel, are among the drugs made directly by Julian, or were indirectly enabled by thechemistry in one of his 160 U.S. patents.
View a NOVA show about him at http://www.pbs.org/wgbh/nova/physics/forgotten-genius.html
http://blogs.scientificamerican.com/urban-scientist/2014/04/11/google-doodle-honors-chemist-dr-percy-julian/
Physiology in the News B (several students)
Measles Outbreak Traced toFully Vaccinated Patient
for First Time
en comes o e meas es vacc ne, wo s o s are e er an one. … ess an o peop e
who get both [measles] shots will contract the potentially lethal skin and respiratory infection. And
even if a fully vaccinated person does become infected—a rare situation known as “vaccine
failure”—they weren’t thought to be contagious.
That’s why a fully vaccinated 22-year-old theater employee in New York City who developed the
measles in 2011 was released without hospitalization or quarantine. But like Typhoid Mary, this
patient turned out to be unwittingly contagious. Ultimately, she transmitted the measles to four
other people, according to a recent report in Clinical Infectious Diseases that tracked symptoms
in the 88 people with whom “Measles Mary” interacted while she was sick. Surprisingly, two of
the secondar atients had been full vaccinated. And althou h the other two had no record of
http://news.sciencemag.org/health/2014/04/measles-outbreak-traced-fully-vaccinated-patient-first-time
.
receiving the vaccine, they both showed signs of previous measles exposure that should haveconferred immunity.
By analyzing her blood, the researchers found that Measles Mary mounted an IgM defense, as if
she had never been vaccinated. Her blood also contained a potent arsenal of IgG antibodies, but
a closer look revealed that none of these IgG antibodies were actually capable of neutralizing the
measles virus. It seemed that her vaccine-given immunity had waned.
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Respiratory Systems
External respiration =
exchange of O2 and CO2
between organism and
environment
Internal respiration =cellular use of O2 in
metabolisms
See also Figs . 11-1 and 1
Respiratory strategies
Animals more than a few millimeters thick use one of
three respiratory strategies:
1) Circulating external medium throughout body
Sponges, cnidarians, and insects
2) Diffusion of gases across body surface +
circulatory transport (bulk flow)
Cutaneous respiration
Most aquatic invertebrates, some amphibians, bird eggs
3) Diffusion of gases across a specialized respiratorysurface + circulatory transport (bulk flow)
Gills (evaginations) or lungs (invaginations)
Vertebrates
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Ventilation
Reduces formation of static boundary layers
Types of ventilation
Nondirectional - medium flows past respiratory
surface in an unpredictable pattern (e.g., frog skin)
Tidal - medium moves in and out (e.g., humans)
Unidirectional - medium enters chamber at one point
and exits at another (e.g., fish, crustaceans, birds)
Animals respond to changes in environmental
O2 or metabolic demands by altering rate orpattern of ventilation
Movement of blood through respiratory surface
can affect efficiency of gas exchangeNondirectional ventilation
(fully mixed medium and
thin surface)
Nondirectional ventilation
(poorly mixed medium or
thick surface) Tidal ventilation
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Unidirectional ventilation - blood can flow in one of
three ways relative to flow of medium
Crosscurrent flowCountercurrent flowCocurrent flow
See also Fig . 11-6, p. 501
The physics of respiratory systems
1) Rate of di ffusion (Fick equation)
dQ/dt = D x A x dC/dx
dQ/dt = rate of diffusion or mass flux (moles/sec)
D = diffusion coefficient (how easy to diffuse) (cm2/sec)
A = membrane area (cm2)
dC/dx = energetic gradient ([ ], pressure, etc.)
Gas exchange surfaces are thin with large
surface area
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Table 11-1, p.464
Venti lation and gas exchange: Water vs air
The different physical properties of air and water
require different strategies from animals
Differences
[O2]air 20-30X greater than [O2]water
Water is denser and more viscous than air
Evaporation only an issue for air breathers
StrategiesUnidirectional: most water-breathers
Tidal: air-breathers
Air-filled tubes: insects
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Fish gills are arranged for countercurrent flow
See Fig. 11-6, p. 501
Breathing in air (compared to water)
O2 easy to get out of air (21% of gases)
For 1 ml O2, need to transport 25 ml of air
For 1 ml O2, need to transport 1 L water
Respiration by diffusion for small animals, ventilated
lungs for most larger ones; some cutaneous respir.
If gills present, need rigid support against gravity
Arthropods – crustaceans, chelicerates, insects, arachnids
Vertebrates
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The lung…
1. Diffusion lungs
no muscular ventilation
Sea cucumber Pulmonate snail
very sma an ma s
invertebrates
2. Ventilation lungs
exchan e via tidal flow
Frog Mammal
amphibians, reptiles, mammals
unidirectional flow - birds
Filling a ventilation lung:
A. pressure pump
Fig. 11-11, p.474
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Relevant pressures during ventilation
http://www.youtube.com/watch?v=NB1aCBId6qA
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Gas exchange at alveoli –
Type I alveolar cells
See also Figs. 11-11
Type II alveolar cells secrete surfactants – reduce surface tension, which increases lung
compliance and decreases force needed to inflate lungs
an -
Reptiles
No true diaphragm - use rib cage to produce negativepressure to fill lungs
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Birds
Lung - stiff, changes little in volume
Series of flexible air sacs act as
bellows
Air sacs ramify into bones
Two bronchi pass through lungs to
air sacs
Gas exchange at parabronchi
Bird ventilation requires
two cycles of inhalationand exhalation
Unidirectional air flow
http://www.peteducation.com
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1st inhale
Anterior air sacs
lung
Posterior air sacstrachea
Anterior air sacs
1st exhale
lung
Posterior air sacstrachea
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2nd inhale
Anterior air sacs
lung
Posterior air sacstrachea
2nd exhale
Anterior air sacs
lung
Posterior air sacstrachea
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Presumed earliest unidirectional
vertebrate lungUpper Cretaceous (85 million years ago) rocks in Argentina
Sereno et al. 2008. PLoS One.
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Insects have extensive tracheal system
Series of air-filled tubes that terminate in tracheolesEnds of tubes are filled with hemolymph – sites of
as exchan e
Open to outside via spiracles
Gases diffuse in and out of trachea
Mechanisms of insect ventilation
Abdominal muscle contractions or thorax movements
Tidal or unidirectional (anterior abdominal spiracles)
e a s e ( m m o l g - 1 m i n - 1 )
OpenClosed phase: no gas exchange.
O2 used and CO2 converted to
HCO3-. in total P
Flutter phase: air is pulled in
R a t e o f C O 2
r e l
Time (h)
Closed
Flutter 2
can no longer be stored as
HCO3-. Spiracles open and
CO2 is released.