Download Gas Exchange and Circulation

Gas Exchange and Circulation
Victoria Cambridge
12TAR
Respiration in Humans
In humans, and also in mammals, respiratory gas exchange is carried out by the
heart and lungs. It is how we get oxygen, from the air, into our blood and the carbon
dioxide out of our system. The Lungs are a pair of organs in the chest which
perform respiration. Humans have two lungs and each lung is between 10 and 12
inches in length. The two lungs are separated by the Mediastinum which contains
the heart, trachea, oesophagus and blood vessels. Within the lungs are the Alveoli
which are small air sacs within the lungs. Respiration happens by the diffusion of
gases across the thin walls of the Alveoli . The Alveoli are surrounded by numerous
small capillaries which means there is lots of blood for the gases to pass into or out
of. The Alveoli have a moist lining which helps to dissolve the gases.
http://en.wikipedia.org
/wiki/Gas_exchange
In humans blood carries oxygen around the body using red blood cells. They have
a double circuit which is where blood flows in two different circuits, one carrying
blood to the lungs and the other carrying blood to the tissues. It is a closed system
where the blood is contained within vessels.
The human heart has four chambers which are seperated pumps, one for each
circuit. The right atrium recieves
deoxygenated blood from the
body at a low pressure and
then pumps it to the right
ventricle which pumps the
dioxygenated blood to the
lungs at pressure. The blood
passes through one way
valves as it passes through
each chamber to prevent
black-flow. The left atrium
recieves oxygenated blood
from the lungs and pumps it to
the left ventricle which pumps
the oxygenated blood to the
http://www.gonzaga.k12.nf.ca/academics/science/s
body at a high pressure.
ci_page/biology/heart.jpg
Humans require more oxygen then fish
and insects as they are larger and need
more energy. As we have high energy
needs and a larger area to get blood to
our system is very efficient and generally
suits our lifestyle.
http://thetragictruth-of-me.deviantart.com/art/Don-t-Speak-83944782
Respiration in Fish
The gills of a fish extract oxygen from the water and excrete carbon dioxide and
other metabolic wastes (e.g. Ammonia or acid). The gills are positioned behind
the head of the fish and are made up of numerous folds of arches and rows of
filaments which gives them a large surface area. These folds are supported and
kept moist by the water coming in from the mouth of the fish and flowing over the
gills. They use a respiration system called the counter current flow. They extract
oxygen from the water by moving in in the opposite direction to the blood.
Oxygen is removed from the water and passes into the blood at the gills, this is
also where carbon dioxide is removed as it diffuses out of the water. Using the
counter current flow fish can extract oxygen at three times the rate that a human
can. Oxygen is carried around the fish using red blood cells.
A fish has an open circulatory system which is the
arrangement of internal transport where there is no
distinction between blood and interstitial fluid. The
fluid “bathes” the organs of the fish directly with
nutrients and oxygen. This fluid is called
hemolymph and while muscular movements of the
animal can help to move the fluid it is very limited
as when the heart relaxes blood is drawn back
towards the heart through a series of open ended
pores.
Fish also have a single circulatory system which
means that blood goes once around the body
before returning to its two-chambered heart. Its
heart is the simplest vertebrate hearts and is made
up of two main chambers. It has a thinly walled
atrium and a muscular ventricle. The atrium pumps
blood into the bentricle which then pumps blood
into the conus which is an elastic compartment
which doesn’t pump but instead stretches and
squeezes. From the conus the blood travels to the
gills of the fish where is becomes oxygen enriched.
This oxygenated blood flows through the body and
then returns to the heart.
http://library.thinkquest.org/C003
Gas exchange for fish is more difficult
than it is for mammals as the
concentration of oxygen in the water is
less then 1% and the amount in the air
is 20%. This means that fish have had
to develop specialized gills for gas
exchange. Without water the gills
collapse and the fish suffocates. Fish
cannot have lungs because water is
denser then air and cannot be
contained in the delicate sac-like lungs
of air breathing mammals. Fish have a
large surface area availible on the folds
of their gills which allows them to
absorb lots of oxygen. As fish are
generally quite small and do not need
lots of energy for activities such as
hunting or running they need less
oxygen then humans and so this
system although not very efficient is
sufficient to the requirements of their
lifestyle.
http://goodbye-kitty975.deviantart.com/art/Happy-Fish-31143682
Respiration in Insects
Insects are different then both humans and fish in the fact that they do
not breathe through their mouths. This is because they have no lungs
and their blood does not carry carbon dioxide or oxygen through their
bodies. Instead of lungs insects have a system a tracheae, which are
tubes that penetrate through the insects body. Air enters into the
tracheae through pores called spiracles which are found on each side of
the insects abdomen. The tube endings in are in contact with cells and
contain a fluid for dissolving gas. This direct exchange provides lots of
energy allowing the insect to patake in high level activities such as
flying or jumping.
http://houstonryan.deviantart.com/art/Praying-Mantis-Autumn-69503538
Insects have an open blood system which
means that the hemolymph baths the
organs and tissues directly.
The insects heart is more commonly
known as the Dorsal Vessel. It is closed
at the posterior end and open at the
anterior end. The dorsal vessel is a
flexible tubes running longitudinally
through the insects thoras, abdomen and
the dorsal body wall. In the abdomen the
dorsel vessel is divided into chambers
seperated by valves called ostia which is
where blood enters the heart. Each
chamber has two alary muscles which
help the flow to the heart by alternately
contracting and expanding. After the
heart is the aorta which is a simple tube
used to transport the haemolymph to the
head of the insect (the anterior end)
where it empties into the body cavity.
http://bugs.bio.usyd.edu.au/Ento
mology/internalAnatomy/imageP
ages/heart.htm
An open system is suitable for
insects because of their small size.
It means shorter distances for the
diffusion of nutrience and materials.
Their systems are only suitable for
small creatures and allows them to
quick diffusion which provides the
power for high energy activities like
flying.
http://triagon.deviantart.com/art/Bee-17686915