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Human Gas Exchange
Lungs
http://www.answers.com/topic/lung?cat=health
The human organ for respiration is the lungs. When breathing, the air enters through
the nose and passes down the trachea into the left and right bronchi. These are each
connected to one lung where it then divides into smaller branches called bronchioles.
These end in alveoli (air sacs). Humans have two lungs that contain 2400km of airways.
Some of the structures within the lungs are:
Larynx: The larynx is an organ found in the neck of an animal. The larynx is also known
as the voice box and is involved in producing sound. When the larynx is stimulated by
foreign matter it produces a strong coughing reflex, so that the matter does not gain
access to the lungs.
Cartilage Rings: Cartilage rings are structures of cartilage in a C shape that surround
the trachea. Their purpose is to reinforce the trachea to maintain an open passageway
for air.
Trachea: The trachea is a windpipe that allows air to pass into the lungs. It is covered
in a layer of mucus that traps any foreign particles before they reach the lungs.
Bronchus: The trachea divides into 2 bronchi (one to the left and one to the right).
They are a passageway for air to pass into the lungs.
Pulmonary Artery: This is where deoxygenated blood from the heart is transported into
the lungs.
Pulmonary Vein: This is where oxygenated blood is carried to the heart from the lungs.
Pulmonary alveolus: A hollow sac that is found in the lungs. They come off the bronchi
and are the site of gas exchange.
Heart
http://en.wikipedia.org/wiki/Image:Diagram_of_the_human_heart_%28cropped%29.svg
The heart is the organ that is responsible for moving blood through the body. It does
this by moving in a regular pumping motion. Some of the structures included in the heart
are:
Aorta: The aorta is an artery originating in the Left Ventricle. It is the largest artery
in the human body. Its task is to bring oxygenated blood to all parts of the body.
Pulmonary Artery: The pulmonary artery’s job is to supply blood to the lungs. It begins
in the Right Ventricle of the heart.
Pulmonary Vein: There are four pulmonary veins in the human heart and they carry
oxygenated blood from the lungs into the Left Atrium.
Pulmonary Valve: The pulmonary valve is located between the Right Ventricle and the
Pulmonary Artery. It allows blood to flow in one direction and it prevents the back flow
of blood as it is pumped from the right ventricle to the pulmonary artery.
Left Atrium: The Left Atrium is one of the four chambers of the human heart. It
receives oxygenated blood from the Pulmonary Vein and pumps it into the Left Ventricle.
Right Atrium: The Right Atrium is one of the four chambers of the human heart. It
receives deoxygenated blood from the Vena Cava’s and pumps it into the Right Ventricle.
Left Ventricle: The Left Ventricle is one of the four chambers of the human heart. It
receives oxygenated blood from the Left Atrium and pumps it into the Aorta.
Right Ventricle: The Right Ventricle is one of the four chambers of the human heart. It
receives deoxygenated blood from the right atrium and pumps it into the Pulmonary
Artery.
Mitral Valve: The Mitral Valve is a flap located between the Left Atrium and Left
Ventricle. It permits blood to flow one way only, from the Left atrium into the Left
ventricle.
Aortic Valve: The Aortic Valve is a flap located between the Left Ventricle and Aorta.
Superior Vena Cava: The Superior Vena Cava is a thick and short vein that carries
deoxygenated blood from the upper half of the body to the Right Atrium.
Inferior Vena Cava: The Inferior Vena Cava is a vein that carries deoxygenated blood
from the lower half of the body to the Right Atrium.
Tricuspid Valve: The Tricuspid Valve is a flap like structure that allows blood to flow in
only one direction. It is located between the Right Atrium and Right Ventricle and
prevents the back flow of blood as it is pumped from the right atrium to the right
ventricle.
Gas Exchange
The site of gas exchange in humans is in the alveoli of the lungs. The alveoli provide a
large surface area for gas exchange to occur (70m2) and have a very thin membrane (0.5
nanometres) which aids rapid diffusion. Oxygen and CO2 is exchanged between the lungs
and the pulmonary capillaries which results in the re-oxygenation of the blood that has
entered the lungs through the pulmonary artery. This blood then returns to the heart
through the pulmonary veins where it is pumped through the rest of the body. CO2 is
diffused into the lung capillaries where it can then be exhaled out of the body.
Fish Gas Exchange
Gills
http://www.mrothery.co.uk/images/gill.gif
The gills are an anatomical structure found in many aquatic creatures. It is an organ that
is responsible for respiration. It does this by extracting oxygen from the water and
expiring carbon dioxide. Gills consist of plates of tissue, that increase the surface area,
through which gases can diffuse. Some of the structures within the gills include:
Afferent Artery: The Afferent Artery brings deoxygenated blood from the heart to
be re-oxygenated.
Efferent Artery: The Efferent Artery takes the re-oxygenated water from the gills to
tissues within the fish’s body.
Primary Gill Filaments: Primary gill filaments are the feather-like projections of the
gills across which diffusion of gases occurs.
Secondary Lamellae: The secondary lamellae cover the primary gill filaments and
contain blood capillaries so that the blood can be oxygenated.
Heart
http://library.thinkquest.org/C003758/Development/fish.htm
The heart of a fish is different from that of a mammal in that instead of having four
chambers it has only two. The disadvantage of this is that there is some mixing of
oxygenated and deoxygenated blood. Some of the structures within the heart of a fish
include:
Atrium: This is a thin walled structure that pumps blood into the ventricle.
Ventricle: This structure pumps blood into the conus.
Conus: The conus is an elastic compartment that cannot pump but rather stretches and
squeezes. From the conus, blood is transported to the gills where it is enriched with
oxygen.
Gas Exchange
Fish obtain the oxygen they need from the water around them. To do this they need a
system that is far more efficient at extracting oxygen than other non-aquatic animals
because of the small amount of oxygen available in water. For this purpose, fish have
gills. The gills of a fish have a large surface area due to the primary gill filaments and
secondary lamellae. Water is either pumped actively across the gills or encouraged by
the fish swimming with its mouth open. Fish have a closed circulatory system in which
the blood is contained solely within the vessels. They also have a single circuit system.
This is where the blood only flows once through the heart in each circulation of the
body. The blood of a fish goes from the heart to the gills where it is oxygenated. This
blood then circulates around the body and returns to the heart as deoxygenated blood
where it begins the cycle again.
Insect Gas Exchange
Spiracle
http://www.dwm.ks.edu.tw/bio/activelearner/44/images/ch44c3.jpg
Spiracle: Spiracles are small openings in an insects body that lead to the respiratory
system. They allow air to enter the trachea and CO 2 to exit. They can be opened and
closed to control water levels within the insect.
Tracheal Tube: The tracheal tube delivers oxygen to the tissues of the insect.
Tracheole: These branch of the tracheal tube and penetrate the tissues of an insect to
provide oxygen. They contain enzymes that get rid of bacteria and particles that may be
harmful.
Heart
http://bugs.bio.usyd.edu.au/Entomology/images/Topics/intAnatomy/heart2.gif
The heart of an insect is a tube that is located just under the surface of the body.
Insect blood does not contain red blood cells so does not have a high oxygen holding
ability. This is countered by the fact that insects have a large surface area: volume ratio
that allows diffusion and osmosis to occur directly into cells in a way that can’t happen in
larger vertebrates. Some of the structures in an insect heart include:
Aorta: This is the large dorsal blood vessel in invertebrates. It pumps blood to the rest
of the body.
Ostium: These are small openings inside the heart.
Gas Exchange
The tracheal system of an insect is where gas exchange occurs, specifically the
tracheoles. Oxygen enters through the spiracles and down the tracheal tubes. It then
goes into the tracheoles where it diffuses into the body tissues. Carbon dioxide moves
in the opposite direction.