Transcript 2a) How many of each type of chamber does the heart of a

Comparing Various Closed
Circulatory Systems
Mammals
Frogs
Fish
Circulation in Mammals (and birds)
Double circulation
FROG
Questions
1a) How many of each kind of chamber does a
frog's heart have?
b) Compare and Contrast the functioning of the
frog’s heart with that of a mammal.
c) The diagram of the path of circulation in a
frog (above) shows that there is an extensive
blood supply to the body wall. Frog's skin is
usually moist. Frogs can spend considerable
time under water. How could this type of
circulation be an advantage when the frog is
underwater?
Frog
Double Circulation
FROG: Circulatory System
Answers
1a) How many of each kind of chamber does a frog's heart have?
Three chambers: 1 Ventricle and 2 Atria
b) Compare and Contrast the functioning of the frog’s heart with that of
a mammal.
They are similar in that both have a right and left atria that
function to receive blood and pump it to the ventricle (s).
But they differ in that oxygen rich and poor blood mix in the
ventricle of the frog and the ventricle functions to send blood
with a relatively low oxygen concentration (compared to in a
mammal) to the tissues of the body.
Mammals don’t have blood returning from the body and the
lungs mixing; they are kept in separate ventricles and so only
oxygen rich blood from the left ventricle is distributed to the
tissues of the body.
So Blood moving to body tissue will contain less oxygen per unit
of volume than mammalian blood
Cont.
c) …..How could this type of circulation be
an advantage when the frog is underwater?
Oxygen (from the water) can be absorbed
across the moist skin of the frog when it
is under water (and can’t use its lungs for
gas exchange). (Oxygen enables aerobic
respiration to proceed and thus ATP to be
produced without waste such as lactic
acid accumulating.)
FISH
Questions
2 a) How many of each type of chamber does the
heart of a fish have?
b) Fish have a single circulation as compared to the
double circulation of mammals. Examine the
diagram of the path of circulation in a fish (above)
and explain what is meant by a single circulation.
c) Suggest a possible advantage of a double
circulatory system over a single circulatory system.
d) Why is a single circulatory system effective for a
fish, when it would be ineffective for a mammal?
Fish
Single circulation
Low
pressure
FISH: Circulatory System Question
2a) How many of each type of chamber does the heart of a fish
have?
1 atrium and 1 ventricle
b) Fish have a single circulation as compared to the double
circulation of mammals. Examine the diagram of the path of
circulation in a fish (above) and explain what is meant by a
single circulation.
Blood moves through the heart only once in each complete
circuit around the body. It goes from heart to gills and from
gills to the rest of the body. (as opposed to double
circulation which involves the blood passing through the
heart twice in each complete circulation of the body. It is
returned to the heart after being reoxygenated at the lungs,
before being pumped to the rest of the body)
c)
Suggest a possible advantage of a double circulatory system over
a single circulatory system
(i)
The heart receives blood which is oxygen rich. The heart is a
muscle and muscle tissue being active requires a rich supply of
oxygen so that ATP can be generated during aerobic respiration
Freshly oxygenated blood will then be pumped by the heart to
other tissues of the body. This pumping forces the blood along
and ensures rapid delivery to tissues.
(single circulation in comparison means the actual heart tissue
only receives oxygen poor blood and that blood pumped to other
tissues is under low pressure and is delivered fairly inefficiently
(ii)
d) Why is a single circulatory system effective for a fish, when it
would be ineffective for a mammal.
Fish are poikilothermic ectotherms (their body temp fluctuates
with that of the environment and they don’t adjust their
production of metabolic heat) and less metabolically active than
mammals. Thus their tissues require less ATP to fulfill their
needs, thus oxygen and glucose can be supplied at a slower rate
for the respiration to still be sufficient. Mammals are
homeothermic endotherms (maintain a stable core temperature
and control generation on metabolic heat to do so) and more
metabolically active and need to supply oxygen and glucose to
cells more efficiently to enable supply of ATP fast enough to
sustain their cells