Transcript Cardivascular System and Diffusion

Cardiovascular System
and Diffusion
Katerina Lin
Kiran Pandher
Rachel Gibbs
Group 5
Goals


Explain how gas exchange takes place at the
cellular level.
What prevents gas from being exchanged in
non-optimal places?
An Overview:
The Respiratory System
Respiratory system: takes oxygen from
the air into the body and releases CO2, the
waste product.
 Gas exchange occurs because of partial
pressure gradients (oxygen and CO2).
Higher pressure = more diffusion.


Lungs: Gases pass through capillaries and
alveoli down partial pressure gradients.
Capillaries and alveoli share a membrane
Body: Gases diffuse through capillaries.
(Starr).

Oxygen…


Simple diffusion
Lungs: oxygen flows from the
alveoli (high) to the
bloodstream (low)
(“Respiration”).


More pressure/higher temp/lower
pH = more oxygen diffuses (Starr).
Most (98.5%) of the oxygen
flowing into the bloodstream
binds onto the hemoglobin in
RBCs
Oxygen does not dissolve well
in blood so needs help from
hemoglobin
(Starr).

(Starr).
Carbon Dioxide…
Simple diffusion
 Body: diffuses from interstitial fluid (high)
into capillaries and carried in blood (low):





10%: dissolves in blood
30%: binds to hemoglobin (carbamino hemoglobin)
60%: becomes bicarbonate (HCO3-) when CO2
dissociates in water or with enzyme (carbonic
anhydrase)
Lung: from the bloodstream (high) to
alveoli (low)
(“Respiration”).

CO2 is released from the CO2 bound to
hemoglobin and HCO3- dissolved in the blood
(Freudenrich).
Diffusion of Carbon Dioxide
What prevents gas from being
exchanged in non-optimal places?
 Surface
areas and rates of flow
influence gas exchange

The more surface area and larger the
partial pressure gradient, the faster
diffusion will occur (Fick’s law)
(Starr).
 Alveoli
sacs provide a lot of surface area for
optimum diffusion.

Gas exchange is most efficient when the
rate of air coming into the body equals
blood flow
(Starr).
What prevents gas from being
exchanged in non-optimal places?


Different parts of body have
characteristics that help create
optimal gas exchange.
Capillaries




Very small and only one cell
thick (“Capillaries”).
Network throughout body
Blood flow slows down
Alveoli


respiratory surface: thin
layer of epithelium/other tissue
that is moist at all times  gas
molecules can diffuse only
when dissolved in a liquid (Starr).
Quick diffusion because very
thin and a lot of surface area
(Starr).
Electron Micrograph of a Capillary
Gas Exchange Simulation!
References








“Capillaries: Connecting Arteries and Veins.” 1996-2009. The
Franklin Institute. 10 Nov. 2009.
<http://www.fi.edu/learn/heart/vessels/capillaries.html>.
Freudenrich, Craig. “How Your Lungs Work.” 30 Oct. 2008. How
Stuff Works. 8 Nov. 2009.
<http://health.howstuffworks.com/lung2.htm#>.
<http://i.ehow.com/images/GlobalPhoto/Articles/5159074/26661
7_Full.jpg>.
<http://student.ccbcmd.edu/courses/bio141/lecguide/unit4/innat
e/images/12188b.jpg>.
<http://www.cdli.ca/~dpower/resp/exchange.htm>.
<http://www.health.com/health/static/hw/media/medical/hw/n55
51117.jpg>.
“Human Physiology: Respiration.” 7 Nov. 2009.
<http://people.eku.edu/ritchisong/RITCHISO//301notes6.htm>.
Starr, Cecie, and Ralph Taggart. Biology: The Unity and Diversity
of Life. 9th ed. United States: Brooks/Cole, 2001.
Note: pictures are also cited throughout this powerpoint in the “Notes” section at the bottom of the screen.