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Lecture 77

BIO SCI 94 Lecture Notes - Lecture 77: Red Blood Cell, Protozoa, Passive Transport


Department
Biological Sciences
Course Code
BIO SCI 94
Professor
Michael Clegg
Lecture
77

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1
RESPIRATORY
SYSTEM
1. Define diffusion. Where does this occur in
the
respiratory system?
A type
of
passive transport (no
ATP
required), therefore,
it
is
a net movement
of
molecules in
and
out
of
the cell across the cell membrane along a concentration gradient,
or
from regions
of
higher
to
regions
of
lower concentration.
It
occurs between water/air and blood.
In
animals with lungs
it
occurs in the alveol
i.
2.
Describe
the
general changes in
gas
exchange mechanism
from
Protozoa
to
Arthropods.
Relate these changes in design
to
increased size and metabolic rate.
Protozoa: Are conformed by few cells (small
size),
and have low metabolic rates.
"'All
ofthe
ir cells come
in
contact
with
environment (important
for
diffusion
to
work).
"'
Therefore, diffusion suffices their vital needs.
Arthropods: Are conformed by many cells (large
size),
and have higher metabolic rates.
"'
Not all
of
their cells
can
come in contact
with
the environment. Therefore diffusion
is
no longer
good enough
to
keep them alive.
"'
A respiratory system was developed.
"'
The respiratory system
of
insects
is
a complex network
of
tubes (called a tracheal system)
that
delivers oxygen-containing air
to
every cell
of
the body.
"'
Air enters the insect's body through valve-like openings
in
the exoskeleton.
These
openings
(called spiracles) are located laterally along the thorax and abdomen
of
most insects -- usually
one pair
of
spiracles per body segment. Air
flow
is
regulated
by
small muscles
that
operate one
or
two
flap-like valves within each spiracle -- contracting
to
close the spiracle,
or
relaxing
to
open it.
3.
What particular changes in gas exchange mechanisms happened in
the
Mollusks and
Arthropods
that
moved
onto
land?
They developed cutaneous respiration. (Gills
~
spiracles).
4.
What
is
external respiration and internal respiration? Define ventilation.
External respiration:
The
exchange
of
gases
between
an
organism's respiratory system and
the environment, e.g. the lungs in vertebrates, and the outside environment.
Internal respiration:
Gas
exchange between
an
organism's tissues (cells) and blood.
Ventilation:
The
pumping
of
water in gills and
of
air in lungs.
5. How do you increase
the
efficiency
of
the
respiratory system?
Increase surface area between
water/air
and blood.
Decrease thickness
of
membrane between
water/air
and
blood.
Increase contact
of
each
red blood cell
with
water/air.
Establish a concentrati
on
gradient
so
gases
diffuse quickly. (Bigger difference
of
concentration between both sides
of
the membrane means faster, more efficient diffusion).
"
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6.
Explain
how
gas
is
exchanged
across
the
skin
(cutaneous respiration).
Which
group
uses
this
method
as
their
only
means
of respiration?
By
diffusion;
gas
exchanged between outside air and capillaries through
the
skin
of
the
animal. A group
of
salamanders
uses
this
as
their
only means
of
respiration.
7. Understand
and
be
able to draw the structure of a gill.
8.
How
is
blood
flow
and
water flow
set
up
in
a counter
exchange
mechanism?
Explain
how
this
works.
How
is
the
cross-current
mechanism
found
in
birds
even
better?
Use
diagrams.
Lamellae are
or
iented parallel
to
the stream
of
water, which always
passes
between them from the
inside
of
the gill apparatus
to
the outside. Blood always flows in the lamellae from the outside
of
the
apparatus inward. Consequently, when blood first enters
the
area
of
respiratory exchange,
it
contacts
water
that
is
almost depleted
of
oxygen. This blood however,
has
even
less
oxygen content,
so
a
gradient exists and oxygen immediately diffuses into
the
blood.
As
the
blood continues through the
lamellae, its oxygen content increases,
but
so
does the oxygen content
of
the ever fresher water wi
th
which
it
comes
in
contact. Thus, a diffusion gradient
is
maintained and gaseous exchange continues until
the blood leaves the lamellae.
The
transfer
of
heat
or
diffusible materials between current
of
gas
or
liquid passing one another in
opposite directions is called Countercurrent
Exchange.
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