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Circulation
Blood in more primitive organisms
Primitive organisms might be absent or if present may be rudimentary
In vertebrates, there is particular organism responsible for transportation of
substances and materials
Heart as pumping organ and blood vessels which restrict flow of blood, type of
system called close circulatory system blood always confined in blood
vessels, blood transports gasses
Functions
Transport of substances
Open circulatory system - anthropods molluscs not confined in blood vessels
Blood transports gasses
Transports heat
Whenever we feel too hot in the core, blood will preferentially cause
flow of heat toward the periphery or edges of the body so heat
can escape from body through diffusion or sweating (evaporative
cooling)
Metabolic products, whenever we breakdown food we eat, blood from small
intestines bring metabolic products to diff. parts of the body after
going through river for screening
Hormones glands particularly endocrine glands - produce hormone
secretions directly to blood stream, many such hormones regulating
autonomic regulatory functions in the body, need to eat to urinate and
to breathe
Wastes transported by the blood excess salt, excess Ion
Blood – liquid medium special type of connective tissue
Origin of the Cardiovascular system
Mesoderm or mesenchyme (loosely arranged cells of mesodermal origin)
Gives rise to blood islands and the muscular heart
Also gives rise to Blood islands precursors of either blood vessels or
blood cells, called this because during the development of the
embryo they’re just small separated structures
Angiogenesis - when blood islands give rise to blood vessels
Hematopoiesis – when blood islands give rise to blood cells
Heart: Once develops in the embryo becomes immediately contractile
Thus, able to pump the blood immediately
Primitively, has four embryonic chambers: sinus venosus – branch of in more
derived or newer vertebrates in the major vein which is the
post and pre cava or superior and inferior vena cavae, atrium,
ventricle, bulbus cordis – give rise to derived or newer
vertebrates to major artery or aorta
This system of having 4 chambers seen in primitive vertebrates which are
mainly the fishes
Mammalian, avian, reptilian and amphibian heart – major blood vessels are
atrium and ventricle
Pre and Post cavae are major veins of vertebrate heart, derived vertebrates
like ourselves mammals, derivatives of sinus venosus – just major
blood vessel that pumps deoxygenated blood into the atrium
Primitive fish heart – find sinus venosus first before blood enters the atrium,
atrium to ventricle, from ventricle have the bulbus cordis which is another chamber
Components of Blood
Plasma: liquid medium, matrix of special connective tissue
All types of connective tissue has a matrix
Formed elements:
Erythrocytes RBCs: Oxygen carriers of blood
Leucocyctes(WBCs): fighting infection and disease, phagocytose on foreign
substances
Thrombocytes (platelets): blood clotting, when have injury responsible for
forming network of proteins that will close wound and prevent too
much blood from flowing out, cells congregate upon the cytoflamage
and fix it with protein fibers
Blood Vessels
Origin comes through process of angiogenesis
Structure:
Layers: tunica intima (innermost), tunica media, tunica adventitia
(outermost) has connections/branches of connective tissue,
Essentially epithelial, very thin since blood vessels
Each one is single layer
Some blood vessels are connected via connective
tissue with surrounding muscle
Smallest blood vessel - Capillaries has one layer normally tunica
intima sites for gas exchange diffusion
Function
Blood transport in closed circulatory system (hemodynamics) –
highest pressure of blood coming from the ventricular contraction the
blood squirts out of the aorta at highest pressure – Systole
Diastole - blood at most relaxed or least pressure going into heart via
atrium
When read blood pressure, 120 is systolic and 80 is diastolic
Blood vessels since muscular in nature, have smooth muscles coming from
mesenchyme able to do muscular actions particularly since they form
a tube, type of muscle action they do is dilation versus constriction
Vasoconstriction - tightens, Vasodilation – loosens
When have blood vessel constricting blood will not flow such as when
an animal with a vertebrate dives underwater its pulmonary
circulation shuts of because its pulmonary artery constricts at
the base, dilates when animal gets off the water and starts to
breathe in air
Aortic arch Evolution
Venous system evolution
Heart evolution
Single vs Double Circulation
Retes
Lymphatic System lymph nodes, what swells when have mumps
Aortic Arch Evolution
Talks about how aorta develops
Aorta – major artery that pumps oxygenated blood from heart to diff. parts of the body
Just 1 aortic arch in the humans in left side of the body, big white artery
Birds have a right aorta, big white artery branches off in the diff. tributaries in the aorta
Ancestors have several
Cladogram
Upper left to lower right
More advanced modifications at the lower right
Dorsal and ventral aortae in adults and embryos
Fish has both Dorsal and Ventral aorta
Ventral Aorta for carrying deoxygenated blood from heart to gills so that blood can
get oxygen from gills found in both adults and embryo
Dorsal aorta oxygenated blood to the body tissues from gills found in both adults
and embryo
Petromyzontiformes
Group of lamphreys
8 or more aortic arches
Makes sense because they have gills
Each aortic arch is for each gill arch, each gill has to have blood vessels so
that can extract oxygen from gills
Primitive fish heart with sinus venosus receiving venous blood from body
tissues, four chambers atrium ventricle, bulbus cortis - conus
arteriosus branches off to ventral aorta, Afferent arteries bring blood
to gills to get oxygen, Efferent bring oxygenated blood to dorsal aorta
for transport
Later innovation 6 aortic arches, 2 reduced, in sharks atleast 1 gill slit is reduced into
spiracle Lessening of number of aortic arches because if you have 1 gills slit
reduced into non respiratory surface don’t need a blood vessel
Chondricthyes
Arterial loops in the pre and post
Lessening of aortic arches, essentially the same
Blood flowing to ventral aorta
Afferent arteries to gills
Efferent arteries to dorsal aorta
First and second aortic arches being lost or modified, in some fishes can have less than
6, more important because first branchial arch becomes the mandibular arch the
second hyoid arch
Actinopterygians bony fishes
Four afferent and efferent branchial arches w/ presure drop across gills
As they pass through gills, pressure drops across them that’s why they are able to
load in oxygen through flow of water
First and second aortic arches, why are they lost?
First branchial arch becomes the mandibular arch and second hyomandibula
Four afferent and efferent branchial arches with pressure drop across gills
Relatively the same execpt the lessening of branchial arches
Pulmonary artery and vein and embryonic ductus arteriosus
Dipnoi lungfishes
Primary modification is the appearance of lung
Primitive condition Lung is still attached to the efferent arteries
Doctus arteriousus primitive connection bet. the lung and arterial system,
eventually becomes lost, don’t have in mammals
Necessary because not exclusively dependent on lungs, have to switch from
lungs to gills depending on condition, cannot live indefinitely outside
water still highly dependent on gills, live outside when drought
Pulmonary artery and vein appearing
Third and fourth artic arches not interrupted by gill capillary, not impt function for
oxygen extraction because by that time they already have gill to supplement
First two lost because they have jaws and hyomandibula
Third and fourth recede lose modification because they have lungs
Interatrial septum – fully developed, partition completely separating left and right
atrium, very special evolutionary modification accompanies appearance of lung, not
appear yet in lung fishes, means pulmonary circulation in lung fishes is not efficient
Urodeles
Complete dependence on pulmonary circulation
Separation bet. left and right atrium necessary to distinguish or separate
oxygenated blood
Rule of thumb, deoxygenated blood always enters the right side, oxygenated enters
left side of heart (can’t have unless have two atria)
In fishes its same blood vessel going into 1 chamber always deoxygenated blood
Lungfishes – left and right atrium are not distinguished but there is somewhat
a partition
Typical fish heart just one flow always deoxygenated blood
Lungfish when uses its lung needs separate
How to prevent mixing there are incomplete partitions, not so efficient, Lungfishes
don’t need to have completely efficient lung for pulmonary circulation
because they switch to that only during certain times
Interatrial septum fully developed
Carotid duct lost in adults, what they develop is carotid arteries - supply our
brain with oxygen much more impt. in organisms
Internal carotid formed by extension of dorsal aorta in adults
Another modification – there’s separation, in amphibians begin to lose dorsal aorta,
just one aorta coming from the heart
Anura
Appearance of Pulmocutaneous artery also seen in salamanders
Takes oxygen or air from both pulmonary path (lung path) and skin cutaneos
Single artery that branches of into the skin and then also has branches into
lungs but all single artery - pulmocutaneous
Doctus arteriosus – begins to get lost in modern amphibians, looses circulatory
function
Ductus arteriosus become ligamentum arteriosum in adults, looses circulatory
function, doesn’t have blood flow anymore, vestigial characteristic
Testudines, Crocodila, Aves, Mammals
Testudines
Squamates (lizards and snakes) – there’s distinct interventricular canal serves as
slight separation bet. left and right ventricle
Complete separation does not appear until you find crocodile group
Crocodiles
Have Foramen of Panizza
Carotids develop from third aortic arch and parts of dorsal and ventral aorta,
much more impt. need much more blood supply for brain for more active
animals
Major diff. between birds and mammals
Birds retain right systemic arch
Mammals retain a left systemic arch only from ancestors
Meaning: Reptilian ancestors have two systemic arches
Crocodile, snake, lizard and turtle heart have left and right aortic arch
Left supplies the viscera, right supplies the upper portion
Recap: Evolution
Shark having around five or six aortic arches
First two become reduced because have mandibular arch and hyoid arch
Teleost Modern Fishes relatively the same, lessening
Lungfish
Develop lung, connection Ductus Arteriosus
Amphibians
Appearance of Pulmocutaneous Artery, further disappearance of aortic arches
because they are not dependent on gills except as juveniles
Reptiles
Still have two aortic arches
Birds
Only retain the right systemic arch
Mammals
Retain only the left
Subclavian blood vessel going to arms
Left systemic arch primarily for viscera
Instead of both aortic arches retained, one becomes retained, still mostly supplies
viscera
Instead of keeping another major artery, switched to just one, more completely left
behind the aquatic environment
Having two systemic arches has advantages to type of lifestyle where organism goes
into water from time to time, Ex. crocodile, turtles
Venous system evolution
In very primitive vertebrates, as embryo develops, you start of having 3 veins
Three major embryological venous systems:
Vitelline (supplies yolk), cardinal (supply upper portions of embryo where
head will develop) eventually give rise to post cava pre cava jugular
vein, lateral (found in side but more inferior region, Abdominal)
All veins come from those three
Anastomoses – repeated branching/linking patterns between primordial or
primitive blood vessels
Vein system is a network of veins result of Anastomoses
All succeeding veins become that through Anastomoses
Post Cava and Pre Cava found in the right side
Initially Major veins emerging into both sides
Eventually during development of embryo, lose it and have branch but only coming
from right, further development you will have further branches, Fuse
together to form single post cava and pre cava
Anastomes – multiple branches and connections forming networks
Heart Evolution
Primitive embryonic chambers: Sinus venosus and conus arteriosus
anterior and posterior
In typical fish heart you have oxygen poor blood entering the heart from the body
via the Sinus venosus
Sinus venosus
Major veins coming back from the body, carrying deoxygenated blood
Single circulation and double circulation
S: One flow of blood through the heart (fishes)
Blood enters the atrium, atrium expands creation of negative pressure, pumped into
ventricle when atrium contracts through atrioventricular valve
structure that closes and opens depending on the need for flow of
substance
Atrium to ventricle
Ventricle to conus arteriousus then branch off into ventral aorta then afferent
arteries into the gills then efferent then dorsal artery
Amphibians have a 3 chambered heart do not have a separation between the ventricle have
a separation between left and right atrium
Ventral aorta then afferent arteries then from gills efferent arteries
No separation of left and right atrium
Oxygenated blood enters left atrium from lungs
Deoxygenated blood enters right atrium from body tissues
When both left and right atria contract both pump blood into common ventricle
Potential complication – mixing of oxygenated and deoxygenated blood
Happens Not as much as you expect, otherwise it will be a very inefficient
respiratory system, reason why they do not mix because of presence
of concavities and pits in muscle of heart ventricle
Amphibians have a cutaneous respiration doesn’t have to be completely
efficient
Trabeculae - serve to separate two types of blood, different in terms of
density, denser will settle in the trabeculae, on top settle the deoxygenated
blood, not really mixed, flow out of ventricle when contracts not really
synchronous, not at same time
Deoxygenated – flow out first, coming from ventricle go to right atrium
Oxygenated – flow out second
If have deoxygenated blood in heart, have to be oxygenated, deoxygenated blood
from ventricle goes to lungs via pulmonary artery
Already oxygenated blood goes to aorta into diff. parts of the body
Reptiles have two aortic arches left and right
Reptile heart
Similar to lizards snakes turtles
Foramen of Panizza – channel that joins left and right aortic arches, becomes
much more important, no complete separation in left and right
ventricle in reptile heart so potential mixing, despite not having
complete septum or partition it is
Divided into three incompletely separated compartments
Cavum venosum
Cavum pulmonale
Cavum arteriosum
Simplified forms
distinction between blue and red
When blood enters atria its deoxygenated enters right atrium coming from
systemic circulation - rest of the body
Red going to left atrium come from lungs carried to heart via pulmonary
vein
Arteries carry oxygenated blood, veins carry deoxygenated blood with
the exeption of pulmonary artery – only artery in the adult vertebrate
that carries deoxygenated blood from ventricle to lungs, pulmonary
vein – only vein in adult vertebrate that carries oxygenated blood
from the lungs back to heart
All other adults veins carry deoxygenated blood
All other adult arteries carry oxygenated blood
In fetus some other veins carrying oxygenated blood
Veins come from mother to embryo, mother has to supply
embryo with oxygenated blood via veins
Post Cava and Pre Cava found in the right side
Veins always go back to heart
Lizard
Oxygenated blood entering left atrium and deox entering the right atrium
Separated but have common ventricle
There’s a potential for mixing, but there’s no mixing actually because there
are compartments
What happens when deoxygenated blood enters right atrium goes to Cavum
venosum – receives deoxygenated blood, blood travels into
interventricular canal - pocket rather isolated from rest of ventricle
into the cavum pulmonale – cavum that pump blood in pulmonary
artery brought toward the lungs
Interventricular canal into cavum pulmonale cavum is a cavity, cavum
pump blood in pulmonary artery brought toward the lungs
At same time oxygenated blood enters the left atrium but goes into a
separate compartment cavum arteriosum
When ventricle contracts, all of the blood pump out at the same time
One in rightside goes to pulmonary artery – path of least resistance
Cavum pulmonary leads directly to pulmonary artery
Cavum pulmonary does not lead only exclusive to pulmonary but also to left
aortic arch
Have implication if animal dives, blood that comes from
cavum pulmonale goes to pulmonary artery, path of least resistance
Blood from cavum arteriosum goes to the left and right aortic
Typical heart of squamate lizard snake or turtle
Cavum pulmonale, Cavum arteriosum, Cavum Venosum
Red arrow going outward – Aorta – blood vessel pumps oxygenated blood out of
heart
Blue arrow going outward – Pulmonary artery – carries deoxygenated blood from
heart to lungs
Blue arrows going inside – comes from major veins going to right atrium – always
receives deoxygenated blood from the body
Left atrium – receives Oxygenated blood from lungs entering pumped into cavum
arteriosum
There’s a partition that is not complete, sort of isolate certain blood flows
Deoxygenated blood entering the Cavum Venosum then going to cavum pulmonale
Deoxygenated blood reached the Cavum Venosum
When ventricle contracts all blood squirt out
Deoxygenated blood goes out of the pulmonary artery
Rather spontaneous blood flow out
Most of oxygenated blood enters spontaneously the aortic arches
The right atrium will receive Deoxygenated blood will go into Cavum Venusom
The left atrium will receive oxygenated blood will go into Cavum Arteriosum carries
deoxygenated blood travels further to Cavum Pulmonale when ventricle
contracts pump blood to pulmonary artery whereas Cavum arteriousum
pump blood directly to Aorta left and right
Cava allowed because of the incomplete partitions
Amphibian one chamber no partitions, function of density
Since there are incomplete partitions, it doesn’t matter if oxygen rich blood on top or
oxygen poor blood bottom because of presence of cavum arteriosum
When animal dives underwater, the pulmonary artery constricts so there will be no blood
entering, where will blood go coming from the Cavum Pulmonale? Instead of going to
pulmonary artery it will go to left aortic arch
Cavum Pulmonale leads into two blood vessels pulmonary artery and left aortic arch
When pulmonary circulation shuts of blood coming from cavum pulmonale has no choice
but to go to left aortic arch, at certain point as animal is under water it will still have
oxygenated blood coming from the left side of ventricle or cavum arteriosum,
pumping blood through the right aorta
When animal is underwater can animal maintain that? No cause eventually it will run
out of oxygen, reason why reptiles can’t live indefinitely underwater
When the animal is underwater, the left aorta is carrying deox right aorta carrying
oxygenated blood
Unless like sea snake that does cutaneous respiration so have to break surface of
water, can borrow oxygen from tissues, to supply parts of the body with
oxygen like brain and heart
Marine turtles can stay for hours in water
Crocodile heart
Distinct difference: Have completely separated left and right ventricle No Cavum
Left and right aortic arches joint together by a channel Foramen of Panizza
Left aortic arch comes from the right side of crocodile heart ventricle
Right aortic comes from the left ventricle
Foramen of panizza
Right side deoxygenated has to go to the lungs
From right ventricle it has to go to the Pulmonary artery, when animal is under the
water it will shut down through vasoconstriction, right ventricle when it
contracts pump blood not into pulmonary artery goes to the left aortic arch
Right aortic arch carry oxygenated at start because it came from left ventricle whose
blood comes from lungs
Blood comes from the lungs, when animal is underwater advantage of foramen of
panizza is it allows for some oxygenated blood to go to left aortic arch so it
can keep on supplying a bit of oxygen in viscera
Left supplies the viscera
Right normally supplies the top parts
Without foramen of panizza, what happens in squamates tendency for viscera to
lose oxygen much more quickly than upper part/brain part crucial part to keep
oxygenated but technically speaking, crocodile can stay under water bec. its viscera
is supplied with oxygen coming from foramen of panizza connection
Mammalian heart
Oxygen-rich blood
enters the heart from the lungs and goes out to the body
Oxygen-poor blood
enters the heart form the body (systemic circulation) and goes out to the
lungs
Right side of heart always carries deoxygenated blood
Left always oxygenated blood
Arteries carry blood away from heart
Veins back to heart
Right atrium always receives deoxy blood
Left always receive oxygenated blood
Arteries always carry oxygenated blood
Veins deoxygenated blood
Pulmonary circulation flow of blood from heart to lungs and back exclusively
Systemic circulation from heart to rest of body and back to heart
Systemic circulation
Deoxygenated blood entering the body through the major veins superior vena cava
and inferior vena cava both bringing blood to right atrium, at the same time
left atrium receives oxygenated blood from lungs via pulmonary veins
Left atrium with oxygenated lungs via the pulmonary veins
When atria contract both pump bood via the respective ventricles
Separate right and left ventricle
Right ventricle receives deoxygenated blood from right atrium
Left Ventricle receives oxygenated blood from left atrium
When Ventricle contracts systolic
Blood from right ventricle to go into the only blood vessel that leads out that is the
pulmonary artery, blood coming from left ventricle goes into major artery or
aorta
Left side of the heart are the ones concerned with pulmonary circulation
Right ventricle pumps blood into lungs
Left pumps blood into the arteries
Single double Circulation
Single circulation blood enters the heart and exits straight single flow
Lungfishes one flow but two flows, one oxygenated one deoxygenated Transition
from single to double
Double in non-fishes blood enters through one opening then exits through another
Both oxygenated and deoxygenated blood in the heart
Retes are veins and arteries help body of animal resist lost of heat
Duck swimming in very cold water tendency of heat in its legs, escape the legs and
go to surrounding water, freeze the legs of the dug and kill the duck, ducks
don’t die normally because they have retes
Arteries bringing blood from heart to limbs, to edges
Once blood reaches edges of feet and if it carries heat with it want heat to be kept
inside body of bird, surrounding the artery it is surrounded by veins, veins
carry blood back to general circulation, carries cold blood, venous blood is
colder than blood in artery
Even before blood in artery reaches the extremities heat is already taken up by each
vein, by time blood reaches the extremities, blood is already cold, no net loss
of heat, heat is already taken by surrounding
Carotid retes so we don’t overheat the brain
Male animals have testicular veins so as not to overheat the testes
Lymphatic system
Accumulation of body fluid, whenever blood is pumped through blood vessels, some
of fluid leaking out, interstitial – rotifers nematodes, found between body
tissues
In cetain parts you can accumulate lymph
In circulation this is what happens
Arteries and Veins, Capillary beds joins them together
Arteries decrease in size called arteriols
Veins decrease in size called venule
Arterial blood carries high pressure blood cause its pumped by the ventricle
Very good analysis is a river very fast going downstream once it joins the open
ocean it decreases pressure
Larger the volume lesser the pressure
Pressure drops considerably, by the time blood enters the venous system, pressure
has been decreased significantly in some 0 capillaries, a network of blood
vessels
High pressure pumping of blood through arteries causes a lot of blood to leak out
that pulls up around blood vessels and tissues is what you call interstitial
fluid or lymph, body has lymph vessels all throughout body lymph nodes
Cannot have indefinite pulling of interstitial fluid otherwise have fluid ruining joints
Edema – excess interstitial fluid, accumulation of fluid in a body part
Not through pressure gradient, through hydrostatic pressure that
fluid leaves the arteries
Body has to get rid of that by getting fluid back into the veins
Through osmotic pressure, More fluid outside than inside vein,
spontaneously some of that fluid will enter the vein so general
circulation resumes, natural process, vessels are rather
attached, one particular function for pulling excess tissue and
another is immune function
Wuchereria bancrofti
Particular nematode that likes dodging itself in lymph tissue carried by mosquito
Drainage of lymph is not efficient, accumulate lymph fluid, Limb swells
Tissue fluid
Causes Elephantiasis
Tissue fluid has to be drained out along with the worms
Given this, expect that arteries are stronger bec. they receive high pressure blood, they
have more elastic fibers than veins that allow arteries to expand, when they receive
high pressure blood aorta has to expand a bit by being elastic, if it weren’t elastic it
might snap or break but bec. it has elastic fibers it is able to accommodate flow by
stretching
As a general rule arteries carry more elastic fibers in their tunica media than veins,
veins, they have valves to prevent backflow, veins carry blood upward
against the defying gravity, veins have to have valves to prevent retrograde
flow, Have surrounding muscles pushing on veins to keep on pumping blood,
Ex. femoral vein - when muscles contract pumping blood upward
Cut through mandibular symphysis
Lower jaw
pull down entire tongue trachea esophagus
Parts of the tongue, taste buds, papillae bumps on surface
salivary glands, esophagus,
epiglottis, leaf shaped structure, glottis, distinct cartilages of trachea, thricoid, larynx
bronchi
have to look for veins and arteries,
not colored, in more equiped institutions, veins are colored with dye, sharks when you
open, colored
Veins are darker, when you see white its an artery,
Systematic, trace the artery from aorta first, goes into the left
pre and post cava vein, post cava