Physiology Lecture 21

8/12/2019 Physiology Lecture 21

http://slidepdf.com/reader/full/physiology-lecture-21 1/17

1

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



2

Announcements

Announcements

http://www.pbs.org/your-inner-fish/watch/



3

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.



4

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



5

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



6

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



7

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



8

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



9

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





11

Relevant pressures during ventilation

http://www.youtube.com/watch?v=NB1aCBId6qA



12

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



13

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



14

1st inhale

Anterior air sacs

lung

Posterior air sacstrachea

Anterior air sacs

1st exhale

lung




15

2nd inhale

Anterior air sacs

lung


2nd exhale

Anterior air sacs

lung




16

Presumed earliest unidirectional

vertebrate lungUpper Cretaceous (85 million years ago) rocks in Argentina

Sereno et al. 2008. PLoS One.



17

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.

Date post:	03-Jun-2018
Category:	Documents
Upload:	jmhiggin9894
View:	217 times
Download:	0 times

Physiology Lecture 21

Documents