Transcript diversity_in_gas_exchange

Diversity In Gas Exchange
- Humans, Insects and Fish.
By Saskia
Human Respiratory System.
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To respire, humans extract
oxygen from the air around them
using their lungs.
The lungs in a human are part of
the respiratory system, which also
consists of airways and respiratory
muscles that control the
movement of air passing in and
out of the body.
When air is breathed in, it moves
through the respiratory system in
the following order : nasal cavity,
pharynx, larynx, trachea, thoracic
cavity (chest), bronchi and finally,
alveoli, the site of the gas
exchange, where it is diffused into
the bloodstream.
Structure of the Human Lungs.
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Nasal Cavity – A large space filled with air above and behind the nose.
Pharynx – A section of the throat that is before the oesophagus. Splits into the
trachea (respiratory system) and the oesophagus (digestive system). Both food and
air pass through it, so a flap of skin called the epiglottis closes the entrance to the
trachea to prevent choking on food.
Larynx – The voice box. Situated just below where the pharynx splits into the trachea
and the oesophagus.
Trachea (windpipe) – A long tube starting where the larynx ends, and ending at the
bronchi. It allows air through to the lungs.
Thoracic Cavity – A chamber in the chest that is protected by muscle, skin and soft
tissue.
Bronchi – An airway that conducts air into the lungs. No gas exchange occurs here.
They split into smaller versions of themselves called bronchioles.
Bronchioles – Braches of the bronchi that do not contain any catriladge. They split
off to form the alveoli.
Alveoli – Small spherical hollow outcroppings of the bronchioles. They are the
primary sites of gas exchange. Alveoli have thin walls, which are moist and elastic.
The diffusion of oxygen into the bloodstream occurs at the alveoli walls (called the
respiratory membrane).
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When a person breathes in, the
oxygen travels down the pharynx,
larynx, windpipe, into the bronchi and
bronchioles and finally into the alveoli,
where the large surface area (about
70-90 square metres) and semi
permeable membrane (called the
respiratory membrane) allows for the
oxygen to be diffused quickly and
efficiently into the bloodstream.
The oxygen diffuses through the
respiratory membrane into capillaries
that are around the alveoli. The
capillaries house red blood cells, and
the oxygen bonds to them and is then
able to be transported to the rest of the
body.
Oxygen is then pumped to the heart
using a process called pulmonary
circulation. The oxygen is taken, and
carbon dioxide is sent back to the
lungs, where it is diffused back from
the bloodstream into the alveoli. It is
then sent back up through the lungs
and expelled through the mouth.
How it works.
Human Circulatory System.
• The circulatory system is a system made up of the heart,
the blood and the blood vessels. It uses a process called
pulmonary circulation to deliver oxygenated blood to the
rest of the body, while pumping deoxygenated blood to
the lungs.
• The human heart beats 70-80 times a minute to deliver
oxygen and nutrients to 300 trillion cells. In a day it
pumps 2,000 gallons of blood. In an average lifetime it
beats more than 2.5 billion times.
Structure Of the Human Heart.
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The heart is divided into four separate chambers by the “interventricular
septum.” These chambers are the right atrium, the left atrium, the right
ventricle and the left ventricle.
Deoxygenated blood is pumped through the right atrium and the right
ventricle to the lungs, while oxygenated blood is through the left atrium and
the left ventricle to the body.
Deoxygenated blood enters the right atrium from the superior vena cava
and the inferior vena cava, while deoxygenated blood leaves the right
ventricle by pulmonary artery.
Oxygenated blood enters the left atrium from the pulmonary veins, while
Oxygenated blood leaves the left ventricle by ascending aorta.
The tricuspid valve in the heart separates the right ventricle and the right
atrium, the pulmonary valve separates the right ventricle from the
pulmonary artery, the bicuspid valve separates the left ventricle and the left
atrium, and the ascending aorta is separated from the right ventricle by the
aortic valve.
How it works.
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1) Deoxygenated blood flows from the body
into the right atrium.
2) Blood flows through the right atrium into
the right ventricle.
3) The right ventricle pumps the blood to the
lungs, where the blood releases waste
gases and picks up oxygen.
4) The newly oxygenated blood returns to
the heart and enters the left atrium.
5) Blood flows through the left atrium into
the left ventricle.
6) The left ventricle pumps the oxygen-rich
blood to all parts of the body.
http://www.pbs.org/wgbh/nova/heart/heartmap.html
Respiration In Fish.
• Fish do not have lungs.
Instead they use structures
called gills to respire.
• Gills are located either side of
the fish’s pharynx, and are
made up of structures called
filaments. In each of these
filaments there is a large
network of capillaries that are
the main sites of gas
exchange. The opening to the
gills is protected by a cover
called the operculum.
How It Works.
• Fish respire by sucking water
into their mouths and pushing
it over their gills. The blood in
the capillaries flows in the
opposite direction and the
oxygen is then able to be
diffused across the capillary
membrane using a process
called countercurrent
exchange.
• When the blood becomes
deoxygenated, it is sent back
to the gills, where it is expelled
through the openings in the
side of the pharynx.
Circulation In Fish.
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Fish’s hearts are relatively simple; they
are only made up of two chambers
(compared to the human, which has 4
chambers), an atrium and a ventricle.
Blood is pumped into the atrium by the
ventricle, and then into the conus,
which is an elastic area whose
purpose is to hold blood. It is able to
expand by stretching when more blood
needs to be held.
After the conus, the blood is pumped
to the gills, where it becomes
oxygenated. After it is pumped to the
rest of the body it becomes
deoxygenated and is returned to the
atrium where it starts the process
again.
The fish’s respiratory system is a
single circuit circulation.
Respiration In Insects.
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An insect’s respiratory system is different to that of a human and a fish. It is a long
and complex network of tubes called a tracheal system. The tracheal system is
separate from the circulatory system, unlike the gills of a fish, or the lungs of a
human.
Air is breathed in through spiracles (which are controlled by valves), where it then
enters a tracheal trunk. Tracheal trunks are longitudinal chambers going up and down
the length of an insects body. After that, the air is diffused throughout a complex web
of tracheal tubes (which are like smaller versions of the tracheal trunk). At the end of
each tracheal branch, there is a tracheole. The gas is able to diffuse through the semi
permeable membrane of the tracheole, which then carries the oxygen to individual
cells.
Blood is not oxygenated, because the oxygen is carried directly to the body cells.
Circulation In Insects.
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Insects have a simple heart
compared to the hearts of a
human or a fish; it is essentially a
tube, open and one end and
closed at the other.
Insects do not have arteries or
veins (open circulatory system)
and their blood just floats around
the body, delivering nutrients to
specific cells.
The blood is sent up through the
tail end of the heart, to the front of
the body and empties in the head.
The blood then flows back to the
end, and the process starts again.
The Circulatory System.
Open/Closed Circulatory System.
Single/Double Circulatory System.
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“The circulatory system is the body's
main transport system, carrying food
and oxygen to the cells and taking
waste products away. Humans have a
double circulatory system because it
has two loops - one from the heart to
the lungs and back, and another from
the heart to the rest of the body and
back. (A single circulatory system,
found for example in fish, has just one
loop from the heart round the body,
passing through the gills on the way.)”
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http://www.bbc.co.uk/schools/gcsebite
size/biology/humansasorganisms/1circ
ulationrev1.shtml
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Insects have an open circulatory system,
unlike a human and a fish, which have
closed circulatory systems.
An open circulatory system is a type of
system that used freely flowing fluid to
transport waste and nutrients to cells, rather
than having them contained in veins.
When an animal has an open circulatory
system, nutrients are delivered directly to
the cells, and all the internal organs are
swimming in blood.
Humans and fish have a closed circulatory
system, while insects have an open
circulatory system.
Conclusion.
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Humans need a double circulatory system because we are larger than
insects or fish, and therefore need more nutrients. The closed circulatory
system ensures that the nutrients and oxygen are delivered to our cells very
fast.
Fish have a single circulatory system because they don’t need the amount
of oxygen that insects or humans have because the water supports them.
Insects are small, and can therefore have an open circulatory system and a
tracheal system, because the nutrients can still be delivered efficiently
(humans can’t have an open circulatory system because they are too large).
Bibliography.
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http://www.scienceclarified.com/Ci-Co/Circulatory-System.html
http://en.wikipedia.org/wiki/Image:Heart-and-lungs.jpg
http://en.wikipedia.org/wiki/Gas_exchange
http://www.gonzaga.k12.nf.ca/academics/science/sci_page/biology/heart.jp
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http://upload.wikimedia.org/wikipedia/commons/thumb/b/bc/Tuna_Gills_cut_out.jpg/6
39px-Tuna_Gills_cut_out.jpg
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookcircSYS.html
http://bugs.bio.usyd.edu.au/Entomology/images/Topics/intAnatomy/heart2.gif
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