May 19, 2023 • 21 mins
This textbook is designed specifically for Kansas State's Biology 198 Class. The course is taught using the studio approach and based on active learning. The studio manual contains all of the learning objectives for each class period and is the record of all student activities. Hence, this textbook is more of a reference tool while the studio manual is the learning tool.
Authors: Robert Bear, David Rintoul, Bruce Snyder, Martha Smith-Caldas, Christopher Herren, and Eva Horne
Kansas State University Libraries
New Prairie Press
Bear, Robert; Rintoul, David; Snyder, Bruce; Smith-Caldas, Martha; Herren, Christopher; and Horne, Eva, "Principles of Biology" (2016). Open Access Textbooks. 1. https://newprairiepress.org/textbooks/1
The textbook was originally published and is also available to download at http://cnx.org/contents/db89c8f8-a27c-4685-ad2a-19d11a2a7e2e@24.1.It is licensed under a Creative Commons Attribution License 4.0 license.
Authors: Robert Bear, David Rintoul, Bruce Snyder, Martha Smith-Caldas, Christopher Herren, and Eva Horne
Kansas State University Libraries
New Prairie Press
Bear, Robert; Rintoul, David; Snyder, Bruce; Smith-Caldas, Martha; Herren, Christopher; and Horne, Eva, "Principles of Biology" (2016). Open Access Textbooks. 1. https://newprairiepress.org/textbooks/1
The textbook was originally published and is also available to download at http://cnx.org/contents/db89c8f8-a27c-4685-ad2a-19d11a2a7e2e@24.1.It is licensed under a Creative Commons Attribution License 4.0 license.
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Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
(00:00):
Welcome to Principles of Biology. Thisbook was written by the Open Alternative Textbook
Initiative at Kansas State University and isbeing released as a podcast and distributed under
the terms of the Creative Commons AttributionLicense. Today's episode is chapter twenty six
point four Systems of Gas Exchange.All hyperlinks, images and sources can be
(00:22):
found at the link to the book. In the description, the inspired and
expired air may be sometimes very usefulby condensing and cooling the blood that possss
through the lungs. I hope thatthe depuration of the blood in that passage
is not only one of the ordinary, but one of the principal uses of
respiration. Robert Boyle in New ExperimentsTouching the Spring of Air, sixteen sixty.
(00:45):
The primary function of the respiratory systemis to deliver oxygen to the cells
of the body's tissues and remove awaste product, carbon dioxide, the process
which Boile called depuration. The mainstructures of the human respiratory system are the
nasal cavity, the rachia, andlungs, and these structures are what brings
oxygen into the human body and removescarbon dioxide from the human body. As
(01:07):
you learned previously, the circulatory systemis responsible for moving oxygen from the lungs
to the tissues and for moving carbondioxide from the tissues and taking it to
the lungs. At the cellular levelof the oxygen is needed to make ATP
from the energy stored in glucose andother organic molecules. Carbon dioxide is a
waste product of harvesting that energy.In other words, the respiratory system gets
(01:30):
the oxygen inside the body. Thecirculatory system moves the oxygen around the body,
getting it to the cells. Thecells use the oxygen to produce energy
and in the process produce carbon dioxideas a waste. The circulatory system removes
the carbon dioxide from the cell anddelivers it to the lungs, and the
respiratory system removes the carbon dioxide fromthe body. Invertebrates, the respiratory and
(01:53):
circulatory work vary closely together in orderto allow for gas exchange between the inside
and outside of the organism. Allaerobic organisms require oxygen to carry out their
metabolic functions. Over evolutionary time,different organisms have devised different means of obtaining
oxygen from the surrounding atmosphere. Theenvironment in which the animal lives greatly determines
(02:16):
how an animal respires. The complexityof the respiratory system is correlated with the
size of the organism. As animalsize increases, diffusion distances increase in the
ratio of surface area to volume drops. In unicellular organisms, diffusion across the
plasma membrane is sufficient for supplying oxygento the cell. Figure diffusion is a
(02:39):
slow passive transport process. Therefore,dependence on diffusion as a means of obtaining
oxygen and removing carbon dioxide remains feasibleonly for small organisms or those with highly
flattened bodies, such as many flatwormsplat helmets. Larger organisms had to evolve
specialized respiratory tissues such as gills,lungs, and respiratory passages, accompanied by
(03:02):
complex circulatory systems to transport oxygen throughouttheir entire body. The photo shows around
green cell with a smooth, shinysurface. The cell resembles a balloon.
The cell of the unicellular algae Ventricaryaventricosa is one of the largest known,
reaching one to five centimeters in diameter. Like all single celled organisms, V.
(03:27):
Ventricosa exchanges gases across the plasma membranedirect diffusion. For small multicellular organisms,
diffusion across the outer membrane is sufficientto meet their oxygen needs. Gas
exchange by direct diffusion across surface membranesis efficient for organisms less than one millimeter
in diameter. In simple organisms,such as nigerians and flatworms, every cell
(03:51):
in the body is close to theexternal environment. Their cells are kept moist
and gases diffused quickly via direct diffusion. Flat Worms are small, literally flat
worms, which breathe through diffusion acrossthe outer surface. Figure. The flat
shape of these organisms increases the surfacearea for diffusion, ensuring that each cell
(04:11):
within the body is close to theouter surface and has access to oxygen.
If the flatworm had a cylindrical body, then the cells in the center would
not be able to get oxygen.The photo shows a worm with a flat,
ribbon like body resting on sand.The worm is black with white spots.
This flatworms process of respiration works bydiffusion across the outer membrane. Credit
(04:35):
Stephen Childs. Skin and gills,earthworms and amphibians use their skin integument as
a respiratory organ A dense network ofcapillaries lies just below the skin and facilitates
gas exchange between the external environment andthe circulatory system. The respiratory surface must
be kept moist in order for thegases to dissolve and diffuse across plasma membranes.
(05:00):
Organisms that live in water need toobtain oxygen from the water. Oxygen
dissolves in water, but at alower concentration than in the atmosphere. The
atmosphere has roughly twenty one percent oxygen. In water, the oxygen concentration is
much less than that. Fish andmany other aquatic organisms have evolved gills to
(05:20):
take up the dissolved oxygen from water. Figure gills are thin tissue filaments that
are highly branched and folded. Whenwater passes over the gills, the dissolved
oxygen in water rapidly diffuses across thegills into the blood stream. The circulatory
system can then carry the oxygenated bloodto the other parts of the body.
(05:42):
In animals that contain coalambic fluid insteadof blood, oxygen diffuses across the gill
surfaces into the coalambic fluid. Gillsare found in mollusks, analids, and
crustaceans. The photo shows a carpwith a wedge of skin at the back
of the head cut away, revealingpain gills. This common carp, like
many other aquatic organisms, as gillsthat allow it to obtain oxygen from water.
(06:08):
Credit guitardued zero twelve slash Wikimedia Commons. The folded surfaces of the gills
provide a large surface area to ensurethat the fish gets sufficient oxygen. Diffusion
is a process in which material travelsfrom regions of high concentration to low concentration
until equilibrium is reached. In thiscase, blood with a low concentration of
(06:29):
oxygen molecules circulates through the gills.The concentration of oxygen molecules in water is
higher than the concentration of oxygen moleculesand gills. As a result, oxygen
molecules diffuse from water high concentration toblood low concentration, as shown in figure.
Similarly, carbon dioxide molecules and theblood diffuse from the blood high concentration
(06:53):
to water low concentration. The illustrationshows of fish with a box indicating the
location and of the gills behind thehead. A close up image shows the
gills, each of which resembles afeathery worm. Two stacks of gills attached
to a structure called the columnar gillarch, forming a tall V. Water
travels and from the outside of theV between each gill, then travels out
(07:15):
of the top of the V.Veins travel into the gill from the base
of the gill arch, and arteriestravel back out on the opposite side.
A close up image of a singlegill shows that water travels over the gill,
passing over deoxygenated veins first, thenover oxygenated arteries. As water flows
over the gills, oxygen is transferredto blood via the veins. Credit Fish
(07:36):
modification of work by Dwane raver Noah. Trachial systems, insect respiration is independent
of its circulatory system. Therefore,the blood does not play a direct role
in oxygen transport. Insects have ahighly specialized type of respiratory system called the
trachial system, which consists of anetwork of small tubes that carries oxygen to
(07:58):
the entire body. The trachial systemis the most direct and efficient respiratory system
in active animals. Insect bodies haveopenings called spiracles along the thorax and abdomen.
These openings connect to the tubular network, allowing oxygen to pass into the
body figure and regulating the diffusion ofC O two and water vapor. Air
(08:20):
enters and leaves the trachial system throughthe spiracles. Some insects can ventilate the
trachial system with body movements. Theillustration shows the trachial system of a bee.
Openings called spiracles appear along the sideof the body. Vertical tubes lead
from the spiracles to a tube thatruns along the top of the body from
(08:41):
front to back. Insects perform respirationvia a trachial system mammalian systems. In
mammals, pulmonary ventilation occurs via inhalationbreathing. During inhalation, air enters the
human body through the nasal cavity locatedjust inside the nose figure. As air
(09:03):
passes through the nasal cavity, theair is worn to body temperature and humidified.
The respiratory tract is coated with mucusto seal the tissues from direct contact
with air. Mucus is high inwater. As air crosses these surfaces of
the mucus membranes, it picks upwater. These processes help equilibrate the air
(09:24):
to the body conditions, reducing anydamage that cold, dry air can cause.
Particulate matter that is floating in theair is removed in the nasal passages
via mucus and cilia. The processesof warming, humidifying, and removing particles
are important protective mechanisms that prevent damageto the trachea and lungs. Thus,
(09:45):
inhalation serves several purposes in addition tobringing oxygen into the respiratory system. The
illustration shows the flow of air throughthe human respiratory system. The nasal cavity
is a wide cavity above and behindthe nostrils, and the pharynx is the
passageway behind the mouth. The nasalcavity and ferynx join and enter the trachia
(10:05):
through the larynx. The larynx issomewhat wider than the trachia and flat.
The trachia has concentric, ring likegrooves, giving it a bumpy appearance.
The trachea bifurcates into two primary bronchi, which are also grooved. The primary
bronchi enter the lungs and branch intosecondary bronchi. The secondary bronchi, in
(10:28):
turn branch into many tertiary bronchi.The tertiary bronchi branch into bronchioles, which
branch into terminal bronchioles. Each terminalbronchiole ends in an alveolar sack. Each
alveolar sac contains many alveoli clustered togetherlike bunches of grapes. The alveolar duct
(10:48):
is the air passage into the alveolarsac. The alveoli are hollow and air
empties into them. Pulinary arteries bringdeoxygenated blood to the alveolar sac and thus
appear blue, and pulmonary veins returnoxygenated blood and thus appear red. To
the heart. Capillaries form a webaround each alveolis. The diaphragm is a
(11:09):
membrane that pushes up against the lungs. Air enters the respiratory system through the
nasal cavity and pharynx and then passesthrough the trachea and into the bronchi,
which bring air into the lungs creditmodification of work by NZI. From the
nasal cavity, air passes through thepharynx throat and the larynx voice box as
(11:31):
it makes its way to the trachea. Figure. The main function of the
trachea is to funnel the inhaled airto the lungs and the exhaled air back
out of the body. The humantrachea is a cylinder about ten to twelve
centimeters long and two centimeters in diameterthat sits in front of the esophagus and
extends from the larynx into the chestcavity, where it divides into the two
primary bronchi at the mid thorax figure. The trachea is lined with mucus producing
(11:56):
goblet cells and ciliated epithelia. Thesilli of propel foreign particles trapped in the
mucus towards the pharynx. The cartilageprovides strength and support to the trachea to
keep the passage open. The smoothmuscle can contract, decreasing the trachea's diameter,
which causes expired air to rush upwardsfrom the lungs at a great force.
(12:18):
The forced exhalation helps expel mucus whenwe cough. Smooth muscle can contract
or relax depending on stimuli from theexternal environment or the body's nervous system.
Lungs, bronchi, and alveoli.The end of the trachea bifurcates divides to
the right and left lungs. Thelungs are not identical. The right lung
(12:41):
is larger and contains three lobes,whereas the smaller left lung contains two lobes.
Figure The muscular diaphragm, which facilitatesbreathing, is inferior below to the
lungs and marks the end of thethoracic cavity. The illustration shows the trachea,
which starts at the top of theneck and continues down down into the
chest, where it branches into thebronchi which enter the lungs. The left
(13:05):
lung has two lobes. The upperlobe is located in front of and above
the lower lobe. The right lunghas three lobes. The upper lobe is
on the top, the lower lobeis on the bottom, and the middle
lobe is sandwiched between them. Thediaphragm presses against the bottom of the lungs
and has the appearance of skin stretchedover the top of a drum. Wide
(13:26):
flops of the diaphragm extend downward onthe front, left and right sides of
the body. On the back,thin flaps of diaphragms stretch downward on either
side of the spine. The tracheabifurcates into the right and left bronchi in
the lungs. The right lung ismade of three lobes and is larger to
(13:46):
accommodate the heart. The left lungis smaller and has only two lobes.
In the lungs, air is divertedinto smaller and smaller passages or bronchi.
Air enters the lungs through the twoprimary may bronchi singular bronchis. Each bronchis
divides into secondary bronchi, then intotertiary bronchi, which in turn divide,
(14:07):
creating smaller and smaller diameter bronchioles.As they split and spread through the lung,
the terminal bronchioles subdivide into microscopic branchescalled respiratory bronchioles. The respiratory bronchioles
subdivide into several alveolar ducks. Numerousalveoli and alveolar sacs surround the alveolar ducks.
(14:28):
The alveolar sacs resemble bunches of grapestethered to the end of the bronchioles
figure. Alveoli are made of thinwalled peranchomal cells, typically one cell thick,
that look like tiny bubbles. Withinthe sacs, alveoli are in direct
contact with capillaries one cell thick ofthe circulatory system. Such intimate contact ensures
(14:50):
that oxygen will diffuse from alveoli intothe blood and be distributed to the cells
of the body. In addition,the carbon dioxide that was produced by cell
as a waste product will diffuse fromthe blood into alveoli to be exhaled.
The illustration shows a terminal bronchial tubebranching into three alveolar ducts. At the
end of each duct is an alveolarsack made up of twenty to thirty alveoli
(15:13):
clustered together like grapes. The airspace in the middle of the alveolar sack,
called the atrium, is continuous withthe air space inside the alveolus,
so that air can circulate from theatrium to the alveolus. Capillaries surround each
alveolus, and this is where gasexchange occurs. A pulonary artery shown in
blue, runs along the terminal bronchiole, bringing deoxygenated blood from the heart to
(15:37):
the alveoli. A pulonary vein shownin red, running along the bronchial brings
oxygenated blood back to the heart.Small flat mucus glands are associated with the
outside of the bronchial tubes. Terminalbronchials are connected by respiratory bronchials to alveolar
ducts and alveolar sacks. Each alvvelar sac contains twenty to thirty spherical alveoli
(16:03):
and has the appearance of a bunchof grapes. Air flows into the atrium
of the alveolar sac, then circulatesinto alveoli, where gas exchange occurs with
the capillaries. Mucus glands secrete mucusinto the airways, keeping them moist and
flexible. Credit modification of work byMarianna ruis vaaale transport of gases in blood.
(16:23):
Once the oxygen diffuses across the alveoli, it enters the bloodstream and is
transported to the tissues, where itis unloaded and carbon dioxide diffuses out of
the blood and into the alveoli tobe expelled from the body. Although gas
exchange is a continuous process, theoxygen and carbon dioxide are transported by different
mechanisms transport of oxygen in the blood. Although oxygen dissolves in blood, only
(16:48):
a small amount of oxygen is transportedthis way. Only one point five percent
of oxygen in the blood is dissolveddirectly into the blood itself. Most oxygen
eight point five percent is bound toa protein called hemoglobin and carried to the
tissues. Hemoglobin hemoglobin or HB,is a protein molecule found in red blood
(17:10):
cells erythrocytes, made of four subunits, two alpha subunits and two beta subunits.
Figure Each subunit surrounds a central heinggroup that contains iron and binds one
oxygen molecule, allowing each hemoglobin moleculeto bind for oxygen molecules. Molecules with
more oxygen bound to the heen groupsare brighter red as a result. Oxygenated
(17:33):
arterial blood, where the HB iscarrying four oxygen molecules, is bright red,
while venous blood that is deoxygenated isdarker red. Partishos disc shaped red
blood cells and aeropoints from a redblood cell to the hemoglobin in part be
Hemoglobin is made up of quilled helices. The left, right, bottom,
and top parts of the molecule aresymmetrical. For small hem groups are associated
(17:59):
with hemoglobin. Oxygen is bound tothe hem the protein inside a red blood
cells that carries oxygen to cells andcarbon dioxide to the lungses b hemoglobin.
Hemoglobin is made up of four symmetricalsubunits and four heing groups. Iron associated
with the hembines oxygen. It isthe iron in hemoglobin that gives blood its
(18:22):
red color. Transport of carbon dioxidein the blood. Carbon dioxide molecules are
transported in the blood from body tissuesto the lungs by one of three methods,
dissolution directly into the blood, bindingto hemoglobin, or carried as a
bicarbonate ion. Several properties of carbondioxide in the blood affect its transport.
First, carbon dioxide is more solublein blood than oxygen. About five to
(18:48):
seven percent of all carbon dioxide isdissolved in the plasma. Second, carbon
dioxide can bind to plasma proteins orcan enter red blood cells and bind to
hemoglobin. This form transports about tenpercent of the carbon dioxide. When carbon
dioxide binds to hemoglobin, a moleculecalled carbaminohemoglobin is formed. Binding of carbon
(19:11):
dioxide to hemoglobin is reversible. Therefore, when it reaches the lungs, the
carbon dioxide can freely dissociate from thehemoglobin and be expelled from the body.
Third, the majority of carbon dioxidemolecules eighty five percent are carried as part
of the bicarbonate buffer system. Inthis system, carbon dioxide diffuses into the
(19:33):
red blood cells. Carbonic in hydraseCAA within the red blood cells quickly converts
the carbon dioxide into carbonic acid Htwo COO three. Carbonic acid is an
unstable intermediate molecule that immediately dissociates intobicarbonate ions hcominus three and hydrogen H plus
ions. Since carbon dioxide is quicklyconverted into bicarbonate ions, this reaction allows
(19:59):
for the continued uptake of carbon dioxideinto the blood down its concentration gradient.
It also results in the production ofH plus ions. If too much H
plus is produced, it can alterblood pH. However, hemoglobin binds to
the free H plus ions and thuslimits shifts in pH. The newly synthesized
(20:19):
by carbonate ion is transported out ofthe red blood cell into the plasma of
the blood and exchange for a chlorideion cl This is called the chloride shift.
When the blood reaches the lungs,the bicarbonate ion is transported back into
the red blood cell in exchange forthe chloride ion. The H plus ion
dissociates from the hemoglobin and binds tothe bicarbonate ion. This produces the carbonic
(20:44):
acid intermediate, which is converted backinto carbon dioxide through the enzymatic action of
CAA. The carbon dioxide produced isexpelled through the lungs during exhalation. Cootwo
plus H two O can become Htwo COO three, carbonic acid can become
HCO three plus H plus bicarbonate.The benefit of the bicarbonate buffer system is
(21:04):
that carbon dioxide is soaked up intothe blood with little change to the pH
of the system. This is importantbecause it takes only a small change in
the overall pH of the body forsevere injury or death to result. The
presence of this bicarbonate buffer system alsoallows for people to travel and live at
high altitudes. When the partial pressureof oxygen and carbon dioxide change. At
(21:26):
high altitudes, the bicarbonate buffer systemadjusts to regulate carbon dioxide while maintaining the
correct pH and the body. Thispodcast will be released episodically and follow the
sections of the textbook in the description. For a deeper understanding, we encourage
you review the text version of thiswork voice by voicemaker dot I n.
(21:48):
This was produced by Brandon Casturo asa creative Common Sense production.
Welcome to Principles of Biology. Thisbook was written by the Open Alternative Textbook
Initiative at Kansas State University and isbeing released as a podcast and distributed under
the terms of the Creative Commons AttributionLicense. Today's episode is chapter twenty six
point four Systems of Gas Exchange.All hyperlinks, images and sources can be
(00:22):
found at the link to the book. In the description, the inspired and
expired air may be sometimes very usefulby condensing and cooling the blood that possss
through the lungs. I hope thatthe depuration of the blood in that passage
is not only one of the ordinary, but one of the principal uses of
respiration. Robert Boyle in New ExperimentsTouching the Spring of Air, sixteen sixty.
(00:45):
The primary function of the respiratory systemis to deliver oxygen to the cells
of the body's tissues and remove awaste product, carbon dioxide, the process
which Boile called depuration. The mainstructures of the human respiratory system are the
nasal cavity, the rachia, andlungs, and these structures are what brings
oxygen into the human body and removescarbon dioxide from the human body. As
(01:07):
you learned previously, the circulatory systemis responsible for moving oxygen from the lungs
to the tissues and for moving carbondioxide from the tissues and taking it to
the lungs. At the cellular levelof the oxygen is needed to make ATP
from the energy stored in glucose andother organic molecules. Carbon dioxide is a
waste product of harvesting that energy.In other words, the respiratory system gets
(01:30):
the oxygen inside the body. Thecirculatory system moves the oxygen around the body,
getting it to the cells. Thecells use the oxygen to produce energy
and in the process produce carbon dioxideas a waste. The circulatory system removes
the carbon dioxide from the cell anddelivers it to the lungs, and the
respiratory system removes the carbon dioxide fromthe body. Invertebrates, the respiratory and
(01:53):
circulatory work vary closely together in orderto allow for gas exchange between the inside
and outside of the organism. Allaerobic organisms require oxygen to carry out their
metabolic functions. Over evolutionary time,different organisms have devised different means of obtaining
oxygen from the surrounding atmosphere. Theenvironment in which the animal lives greatly determines
(02:16):
how an animal respires. The complexityof the respiratory system is correlated with the
size of the organism. As animalsize increases, diffusion distances increase in the
ratio of surface area to volume drops. In unicellular organisms, diffusion across the
plasma membrane is sufficient for supplying oxygento the cell. Figure diffusion is a
(02:39):
slow passive transport process. Therefore,dependence on diffusion as a means of obtaining
oxygen and removing carbon dioxide remains feasibleonly for small organisms or those with highly
flattened bodies, such as many flatwormsplat helmets. Larger organisms had to evolve
specialized respiratory tissues such as gills,lungs, and respiratory passages, accompanied by
(03:02):
complex circulatory systems to transport oxygen throughouttheir entire body. The photo shows around
green cell with a smooth, shinysurface. The cell resembles a balloon.
The cell of the unicellular algae Ventricaryaventricosa is one of the largest known,
reaching one to five centimeters in diameter. Like all single celled organisms, V.
(03:27):
Ventricosa exchanges gases across the plasma membranedirect diffusion. For small multicellular organisms,
diffusion across the outer membrane is sufficientto meet their oxygen needs. Gas
exchange by direct diffusion across surface membranesis efficient for organisms less than one millimeter
in diameter. In simple organisms,such as nigerians and flatworms, every cell
(03:51):
in the body is close to theexternal environment. Their cells are kept moist
and gases diffused quickly via direct diffusion. Flat Worms are small, literally flat
worms, which breathe through diffusion acrossthe outer surface. Figure. The flat
shape of these organisms increases the surfacearea for diffusion, ensuring that each cell
(04:11):
within the body is close to theouter surface and has access to oxygen.
If the flatworm had a cylindrical body, then the cells in the center would
not be able to get oxygen.The photo shows a worm with a flat,
ribbon like body resting on sand.The worm is black with white spots.
This flatworms process of respiration works bydiffusion across the outer membrane. Credit
(04:35):
Stephen Childs. Skin and gills,earthworms and amphibians use their skin integument as
a respiratory organ A dense network ofcapillaries lies just below the skin and facilitates
gas exchange between the external environment andthe circulatory system. The respiratory surface must
be kept moist in order for thegases to dissolve and diffuse across plasma membranes.
(05:00):
Organisms that live in water need toobtain oxygen from the water. Oxygen
dissolves in water, but at alower concentration than in the atmosphere. The
atmosphere has roughly twenty one percent oxygen. In water, the oxygen concentration is
much less than that. Fish andmany other aquatic organisms have evolved gills to
(05:20):
take up the dissolved oxygen from water. Figure gills are thin tissue filaments that
are highly branched and folded. Whenwater passes over the gills, the dissolved
oxygen in water rapidly diffuses across thegills into the blood stream. The circulatory
system can then carry the oxygenated bloodto the other parts of the body.
(05:42):
In animals that contain coalambic fluid insteadof blood, oxygen diffuses across the gill
surfaces into the coalambic fluid. Gillsare found in mollusks, analids, and
crustaceans. The photo shows a carpwith a wedge of skin at the back
of the head cut away, revealingpain gills. This common carp, like
many other aquatic organisms, as gillsthat allow it to obtain oxygen from water.
(06:08):
Credit guitardued zero twelve slash Wikimedia Commons. The folded surfaces of the gills
provide a large surface area to ensurethat the fish gets sufficient oxygen. Diffusion
is a process in which material travelsfrom regions of high concentration to low concentration
until equilibrium is reached. In thiscase, blood with a low concentration of
(06:29):
oxygen molecules circulates through the gills.The concentration of oxygen molecules in water is
higher than the concentration of oxygen moleculesand gills. As a result, oxygen
molecules diffuse from water high concentration toblood low concentration, as shown in figure.
Similarly, carbon dioxide molecules and theblood diffuse from the blood high concentration
(06:53):
to water low concentration. The illustrationshows of fish with a box indicating the
location and of the gills behind thehead. A close up image shows the
gills, each of which resembles afeathery worm. Two stacks of gills attached
to a structure called the columnar gillarch, forming a tall V. Water
travels and from the outside of theV between each gill, then travels out
(07:15):
of the top of the V.Veins travel into the gill from the base
of the gill arch, and arteriestravel back out on the opposite side.
A close up image of a singlegill shows that water travels over the gill,
passing over deoxygenated veins first, thenover oxygenated arteries. As water flows
over the gills, oxygen is transferredto blood via the veins. Credit Fish
(07:36):
modification of work by Dwane raver Noah. Trachial systems, insect respiration is independent
of its circulatory system. Therefore,the blood does not play a direct role
in oxygen transport. Insects have ahighly specialized type of respiratory system called the
trachial system, which consists of anetwork of small tubes that carries oxygen to
(07:58):
the entire body. The trachial systemis the most direct and efficient respiratory system
in active animals. Insect bodies haveopenings called spiracles along the thorax and abdomen.
These openings connect to the tubular network, allowing oxygen to pass into the
body figure and regulating the diffusion ofC O two and water vapor. Air
(08:20):
enters and leaves the trachial system throughthe spiracles. Some insects can ventilate the
trachial system with body movements. Theillustration shows the trachial system of a bee.
Openings called spiracles appear along the sideof the body. Vertical tubes lead
from the spiracles to a tube thatruns along the top of the body from
(08:41):
front to back. Insects perform respirationvia a trachial system mammalian systems. In
mammals, pulmonary ventilation occurs via inhalationbreathing. During inhalation, air enters the
human body through the nasal cavity locatedjust inside the nose figure. As air
(09:03):
passes through the nasal cavity, theair is worn to body temperature and humidified.
The respiratory tract is coated with mucusto seal the tissues from direct contact
with air. Mucus is high inwater. As air crosses these surfaces of
the mucus membranes, it picks upwater. These processes help equilibrate the air
(09:24):
to the body conditions, reducing anydamage that cold, dry air can cause.
Particulate matter that is floating in theair is removed in the nasal passages
via mucus and cilia. The processesof warming, humidifying, and removing particles
are important protective mechanisms that prevent damageto the trachea and lungs. Thus,
(09:45):
inhalation serves several purposes in addition tobringing oxygen into the respiratory system. The
illustration shows the flow of air throughthe human respiratory system. The nasal cavity
is a wide cavity above and behindthe nostrils, and the pharynx is the
passageway behind the mouth. The nasalcavity and ferynx join and enter the trachia
(10:05):
through the larynx. The larynx issomewhat wider than the trachia and flat.
The trachia has concentric, ring likegrooves, giving it a bumpy appearance.
The trachea bifurcates into two primary bronchi, which are also grooved. The primary
bronchi enter the lungs and branch intosecondary bronchi. The secondary bronchi, in
(10:28):
turn branch into many tertiary bronchi.The tertiary bronchi branch into bronchioles, which
branch into terminal bronchioles. Each terminalbronchiole ends in an alveolar sack. Each
alveolar sac contains many alveoli clustered togetherlike bunches of grapes. The alveolar duct
(10:48):
is the air passage into the alveolarsac. The alveoli are hollow and air
empties into them. Pulinary arteries bringdeoxygenated blood to the alveolar sac and thus
appear blue, and pulmonary veins returnoxygenated blood and thus appear red. To
the heart. Capillaries form a webaround each alveolis. The diaphragm is a
(11:09):
membrane that pushes up against the lungs. Air enters the respiratory system through the
nasal cavity and pharynx and then passesthrough the trachea and into the bronchi,
which bring air into the lungs creditmodification of work by NZI. From the
nasal cavity, air passes through thepharynx throat and the larynx voice box as
(11:31):
it makes its way to the trachea. Figure. The main function of the
trachea is to funnel the inhaled airto the lungs and the exhaled air back
out of the body. The humantrachea is a cylinder about ten to twelve
centimeters long and two centimeters in diameterthat sits in front of the esophagus and
extends from the larynx into the chestcavity, where it divides into the two
primary bronchi at the mid thorax figure. The trachea is lined with mucus producing
(11:56):
goblet cells and ciliated epithelia. Thesilli of propel foreign particles trapped in the
mucus towards the pharynx. The cartilageprovides strength and support to the trachea to
keep the passage open. The smoothmuscle can contract, decreasing the trachea's diameter,
which causes expired air to rush upwardsfrom the lungs at a great force.
(12:18):
The forced exhalation helps expel mucus whenwe cough. Smooth muscle can contract
or relax depending on stimuli from theexternal environment or the body's nervous system.
Lungs, bronchi, and alveoli.The end of the trachea bifurcates divides to
the right and left lungs. Thelungs are not identical. The right lung
(12:41):
is larger and contains three lobes,whereas the smaller left lung contains two lobes.
Figure The muscular diaphragm, which facilitatesbreathing, is inferior below to the
lungs and marks the end of thethoracic cavity. The illustration shows the trachea,
which starts at the top of theneck and continues down down into the
chest, where it branches into thebronchi which enter the lungs. The left
(13:05):
lung has two lobes. The upperlobe is located in front of and above
the lower lobe. The right lunghas three lobes. The upper lobe is
on the top, the lower lobeis on the bottom, and the middle
lobe is sandwiched between them. Thediaphragm presses against the bottom of the lungs
and has the appearance of skin stretchedover the top of a drum. Wide
(13:26):
flops of the diaphragm extend downward onthe front, left and right sides of
the body. On the back,thin flaps of diaphragms stretch downward on either
side of the spine. The tracheabifurcates into the right and left bronchi in
the lungs. The right lung ismade of three lobes and is larger to
(13:46):
accommodate the heart. The left lungis smaller and has only two lobes.
In the lungs, air is divertedinto smaller and smaller passages or bronchi.
Air enters the lungs through the twoprimary may bronchi singular bronchis. Each bronchis
divides into secondary bronchi, then intotertiary bronchi, which in turn divide,
(14:07):
creating smaller and smaller diameter bronchioles.As they split and spread through the lung,
the terminal bronchioles subdivide into microscopic branchescalled respiratory bronchioles. The respiratory bronchioles
subdivide into several alveolar ducks. Numerousalveoli and alveolar sacs surround the alveolar ducks.
(14:28):
The alveolar sacs resemble bunches of grapestethered to the end of the bronchioles
figure. Alveoli are made of thinwalled peranchomal cells, typically one cell thick,
that look like tiny bubbles. Withinthe sacs, alveoli are in direct
contact with capillaries one cell thick ofthe circulatory system. Such intimate contact ensures
(14:50):
that oxygen will diffuse from alveoli intothe blood and be distributed to the cells
of the body. In addition,the carbon dioxide that was produced by cell
as a waste product will diffuse fromthe blood into alveoli to be exhaled.
The illustration shows a terminal bronchial tubebranching into three alveolar ducts. At the
end of each duct is an alveolarsack made up of twenty to thirty alveoli
(15:13):
clustered together like grapes. The airspace in the middle of the alveolar sack,
called the atrium, is continuous withthe air space inside the alveolus,
so that air can circulate from theatrium to the alveolus. Capillaries surround each
alveolus, and this is where gasexchange occurs. A pulonary artery shown in
blue, runs along the terminal bronchiole, bringing deoxygenated blood from the heart to
(15:37):
the alveoli. A pulonary vein shownin red, running along the bronchial brings
oxygenated blood back to the heart.Small flat mucus glands are associated with the
outside of the bronchial tubes. Terminalbronchials are connected by respiratory bronchials to alveolar
ducts and alveolar sacks. Each alvvelar sac contains twenty to thirty spherical alveoli
(16:03):
and has the appearance of a bunchof grapes. Air flows into the atrium
of the alveolar sac, then circulatesinto alveoli, where gas exchange occurs with
the capillaries. Mucus glands secrete mucusinto the airways, keeping them moist and
flexible. Credit modification of work byMarianna ruis vaaale transport of gases in blood.
(16:23):
Once the oxygen diffuses across the alveoli, it enters the bloodstream and is
transported to the tissues, where itis unloaded and carbon dioxide diffuses out of
the blood and into the alveoli tobe expelled from the body. Although gas
exchange is a continuous process, theoxygen and carbon dioxide are transported by different
mechanisms transport of oxygen in the blood. Although oxygen dissolves in blood, only
(16:48):
a small amount of oxygen is transportedthis way. Only one point five percent
of oxygen in the blood is dissolveddirectly into the blood itself. Most oxygen
eight point five percent is bound toa protein called hemoglobin and carried to the
tissues. Hemoglobin hemoglobin or HB,is a protein molecule found in red blood
(17:10):
cells erythrocytes, made of four subunits, two alpha subunits and two beta subunits.
Figure Each subunit surrounds a central heinggroup that contains iron and binds one
oxygen molecule, allowing each hemoglobin moleculeto bind for oxygen molecules. Molecules with
more oxygen bound to the heen groupsare brighter red as a result. Oxygenated
(17:33):
arterial blood, where the HB iscarrying four oxygen molecules, is bright red,
while venous blood that is deoxygenated isdarker red. Partishos disc shaped red
blood cells and aeropoints from a redblood cell to the hemoglobin in part be
Hemoglobin is made up of quilled helices. The left, right, bottom,
and top parts of the molecule aresymmetrical. For small hem groups are associated
(17:59):
with hemoglobin. Oxygen is bound tothe hem the protein inside a red blood
cells that carries oxygen to cells andcarbon dioxide to the lungses b hemoglobin.
Hemoglobin is made up of four symmetricalsubunits and four heing groups. Iron associated
with the hembines oxygen. It isthe iron in hemoglobin that gives blood its
(18:22):
red color. Transport of carbon dioxidein the blood. Carbon dioxide molecules are
transported in the blood from body tissuesto the lungs by one of three methods,
dissolution directly into the blood, bindingto hemoglobin, or carried as a
bicarbonate ion. Several properties of carbondioxide in the blood affect its transport.
First, carbon dioxide is more solublein blood than oxygen. About five to
(18:48):
seven percent of all carbon dioxide isdissolved in the plasma. Second, carbon
dioxide can bind to plasma proteins orcan enter red blood cells and bind to
hemoglobin. This form transports about tenpercent of the carbon dioxide. When carbon
dioxide binds to hemoglobin, a moleculecalled carbaminohemoglobin is formed. Binding of carbon
(19:11):
dioxide to hemoglobin is reversible. Therefore, when it reaches the lungs, the
carbon dioxide can freely dissociate from thehemoglobin and be expelled from the body.
Third, the majority of carbon dioxidemolecules eighty five percent are carried as part
of the bicarbonate buffer system. Inthis system, carbon dioxide diffuses into the
(19:33):
red blood cells. Carbonic in hydraseCAA within the red blood cells quickly converts
the carbon dioxide into carbonic acid Htwo COO three. Carbonic acid is an
unstable intermediate molecule that immediately dissociates intobicarbonate ions hcominus three and hydrogen H plus
ions. Since carbon dioxide is quicklyconverted into bicarbonate ions, this reaction allows
(19:59):
for the continued uptake of carbon dioxideinto the blood down its concentration gradient.
It also results in the production ofH plus ions. If too much H
plus is produced, it can alterblood pH. However, hemoglobin binds to
the free H plus ions and thuslimits shifts in pH. The newly synthesized
(20:19):
by carbonate ion is transported out ofthe red blood cell into the plasma of
the blood and exchange for a chlorideion cl This is called the chloride shift.
When the blood reaches the lungs,the bicarbonate ion is transported back into
the red blood cell in exchange forthe chloride ion. The H plus ion
dissociates from the hemoglobin and binds tothe bicarbonate ion. This produces the carbonic
(20:44):
acid intermediate, which is converted backinto carbon dioxide through the enzymatic action of
CAA. The carbon dioxide produced isexpelled through the lungs during exhalation. Cootwo
plus H two O can become Htwo COO three, carbonic acid can become
HCO three plus H plus bicarbonate.The benefit of the bicarbonate buffer system is
(21:04):
that carbon dioxide is soaked up intothe blood with little change to the pH
of the system. This is importantbecause it takes only a small change in
the overall pH of the body forsevere injury or death to result. The
presence of this bicarbonate buffer system alsoallows for people to travel and live at
high altitudes. When the partial pressureof oxygen and carbon dioxide change. At
(21:26):
high altitudes, the bicarbonate buffer systemadjusts to regulate carbon dioxide while maintaining the
correct pH and the body. Thispodcast will be released episodically and follow the
sections of the textbook in the description. For a deeper understanding, we encourage
you review the text version of thiswork voice by voicemaker dot I n.
(21:48):
This was produced by Brandon Casturo asa creative Common Sense production.
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