Transcript Every eukaryotic cell needs oxygen. So the big

Every eukaryotic cell needs oxygen.
So the big question is...
Small Organisms
(single or few cells)
• Single-celled organisms can simply absorb
Oxygen from the environment through diffusion
• No circulatory or pulmonary system needed
Just a large surface area that is moist is all that is
needed.
Complex Water Organisms
• Water is a more efficient
exchange medium for
Oxygen (than air)
• But Water has a lower
percentage of Oxygen
dissolved in it (than air)
• Gills develop to maximize
surface area
– Constant circulation of
water
– Water is difficult to move
• Bulk Flow now necessary
Complex Land Animals
• Air is a less efficient
means of absorbing
Oxygen than water
• Air has a higher percent
of Oxygen than water
• Lungs evolve to
maximize surface area
– S.A. of tennis court
– Intercostal/diaphragm
muscles allow periodic
exchange
• Bulk Flow also necessary
The 4 steps of Respiration in Mammals
1. Air or water, containing oxygen, is moved past a
respiratory surface by bulk flow.
2. O2 and CO2 are exchanged through the respiratory surface
by diffusion. O2 enters the capillaries and CO2 is removed.
3. Gases are transported between the respiratory system &
the tissues by the bulk flow of blood (pumped by the heart)
4.Gas exchange between tissue and circulatory system. O2
diffuses out of capillaries and CO2 diffuses into them.
Diffusion =
movement of particles from a region of high
concentration to one of low concentration.
Bulk flow =
movement of many particles from an area of
higher pressure to one of lower pressure
Diffusion of O2 and CO2
• When a cell carrying O2
nears another cell that is
lacking in O2, diffusion
will occur
• When a cell is lacking in
O2 and nears an O2 rich
region, diffusion will
occur
• The same process
happens with CO2
Summary of diffusion in the lungs and tissue
So now we understand how this diffusion works
between neighboring cells
The next question is...
Transporting O2 and other stuff
(The Circulatory System)
• A liquid conduit
containing the liquid
“blood”
• This Bulk Flow is
necessary to bring O2 to
every cell in the body
• Also necessary to protect
and upkeep cells
• The liquid that is
circulated around has a
number of components...
The Components of Blood
• Red Blood Cells:
– Transport O2
• White Blood Cells:
– Protect the cells from
infection/invasion
• Platelets:
– Clot the blood to prevent it from
spilling out when a rupture of the
fluid conduit occurs
• Plasma:
– Glucose, hormones, etc.
suspended in a viscous goo
Functions of Blood
1. Transportation:
Blood transports oxygen, carbon dioxide,
nutrients, hormones, heat, and wastes.
2. Regulation:
Blood helps regulate pH, body temperature,
and water content of cells.
3. Protection:
Protects against blood loss through clotting,
and against foreign microbes and toxins
through the activities of phagocytic white
blood cells and plasma proteins.
Red Blood Cells
• Have a protein called
“Hemoglobin” which binds
to O2
• Binds to CO much more
strongly
• Contain no nucleus!
• Recycled every week or so
• Biconcave shape
Oxygen atoms bond to the heme
Each can hold 4 o
White Blood Cells
• Slip in between cells
• Recognize and destroy foreign matter
Platelets
• Aid in blood clotting
• Recognize micro tears in blood conduits and
bind together to form a clot
How blood is transported
• Arteries:
– Structures that carry blood
away from the heart
– Rigid to take pressure of
blood right out of heart
• Veins:
– Looser to expand more
– Store great quantities of
blood
• Capillaries:
– Very narrow tubes between
arteries and veins where
diffusion occurs
How Blood Flows:
The Heart
The Heart
• Contraction of ventricles
– Larger of heart chambers
– Takes blood in from the atria
– Pumps blood out to the body
• Contraction of atria
– Smaller chambers
– Takes blood in from body
– Pumps blood into the
ventricles
• Coordinated beating of one
then the other