Circulatory system
Spleen
White pulp – macrophages, monocyte storage
Red pulp - (RBC) storage, and prod’n (in nonmammals)
Vertebrate hearts
Pericardial cavity – division in coelum
Endocardium continuous w/endothelium
of blood vessels
Blood vessels
Artery
smooth
muscle
elastic tissue
Arteriole
elastic tissue
smooth muscle
Capillary
Vein
endothelium
Arteries contain
connective tissue
with elastin and
collagen
endothelium
endothelium
smooth muscle,
elastic fibers
endothelium
valve
Veins include
valves
Artery
Vessel walls
Artery
Vein
Vein
Large arteries
Elastic recoil from
arteries drives flow of
blood during diastole
Systole
Arteries temporarily
expand and hold
pumped blood
Diastole
Veins
Most of the blood volume is in venous
system (60-70%) - resevoir
Blood volume is variable
Vertebrate circulation
Vertebrate circulatory systems are either a
single circuit (fish) or double circuit (tetrapods)
Heart and vessel development
p. 607
Early circulation - amphibian
26 day old human embryo
Ventral aorta, aortic arches, dorsal aorta
Ancestral vertebrate pattern
Dorsal Aorta
Paired dorsal Aortae
Internal Carotid
6 VI 5
V
4
IV 3
III
Ventral Aorta
Heart
2
II 1 I
p.621
Venous development
Sinous venosus, hepatic portal system
Fish circulation
 Heart is below pharynx, near gills
 4 chambers in sequence
 Stiff tissue around heart allow sinus venosus
suction during diastole (no collapse)
Fish circulation
Conus arteriosus – muscular, maintains
pressure during diastole
Teleosts – bulbus arteriosus – enlarged
elastic ventral aorta
Fish circulation
In fish, the aortic arches (AA) are the
afferent and efferent branchial arteries
Aortic arches
Aortic arches in tetrapods
3rd AA – Carotid
4th AA – Systemic arch (dorsal aorta - many
branches!)
6th AA – Pulmonary arch
Tetrapod hearts
 Sinus venosus and conus arteriosis are
lost/reduced
sinus venosus reduced to junction of vena
cava and rt. atrium
 Blood returns from two sources
Many tetrapods have
incomplete separations
Amphibians
Dipnoi
Ancestral crossopterygii
Reptiles
Many tetrapods have
incomplete separations
Amphibians
Dipnoi
Ancestral crossopterygii
Reptiles
Often not using lungs!
Most blood in systemic
Shunting a must
Lungfish aortic arches
facing
A fish with
pulmonary
circulation
In other fish,
swim bladders
supplied from
dorsal aorta
Aquatic
2
3
On land
4
5
6
Lungfish heart
Has incomplete separation of both rt. & lt.
atria; and rt. & lt. ventricles
Yet two ‘streams’ are separate
O2 poor to 5th and 6th (back gills and lung).
AA 3 and 4
O2 rich to 3rd and 4th.
AA 5 and 6
Spiral valve in conus
spiral
valve
Ventricle
septum
Amphibian circulation
Metamorphosis – heart moves towards lungs
AA’s are ‘traditional’ tetrapod: 3,4,6 (frog)
Amphibian heart
Atria are completely divided, ventricle
division is incomplete
Yet very little mixing occurs
Amphibian heart
Ventricle has spongy pockets (trabeculae)
Trabeculae separate deoxy. and oxygenated
blood in ventricle
trabeculae
trabeculae
Frog heart
Frog heart
Frog heart
Frog heart
Frog heart
Ventricle
contraction
Frog heart
Frog spiral valve
Spiral valve in conus arteriosus
Ventral aorta
shortened
to truncus
arteriosus
Reptile circulation
Truncus arteriosus
has three trunks
LS
P
RS
Reptile heart
When not ventilating lungs, pulmonary
resistance increases, blood is shunted from rt
ventricle to lt systemic
Reptile heart
High CO2, acidity causes Bohr effect and
hemoglobin loses affinity for O2
sea snake
Saturation curve
shifts to the right
Early ventricle contraction
Late ventricle contraction
Crocodilia heart
Ventricles divided
Crocodiles have foramen
of Panizza connecting rt.
and lf. systemic
Lf systemic can receive rt.
ventricle blood
Crocodilia heart
higher
valve pressure
Using lungs
Foramen of Panizza
allows Ox. blood into
left systemic
Crocodilia heart
lower
pressure
Cog
DivingF. of P. allows mixed
blood to flow into right
systemic
Bird
Mammal
Systemic arch is one-sided in endotherms
p.618
Dinosaur heart – endothermic!
N.C. Museum of Natural Science
Human
development
Human heart development
One-way flow
in early
development
Adult mammal circulation
Amniote fetus circulation
Oxygenated blood to fetus coming from
outside, not lungs
developing reptiles, birds, mammals
Fetal circulation
Blood flows through umbilical vein, through
ductus venosus to vena cava
Fetal circulation
Most blood from right atrium goes through
foramen ovale to left atrium
Fetal circulation
Meanwhile....some blood in right atrium
goes instead to right ventricle
Most right ventricle
blood goes through
ductus arteriosus
to aorta
Neonatal circulation
At birth pulmonary pressure reduces below
systemic
Foramen ovale
After a day or more:
Ductus arteriosus
Fossa ovalis
Ligamentum
arteriosum
Neonatal problems
Patent foramen ovale
(20% of people)
chest pressure causes
flap to open, strokes
Patent ductus arteriosus
Heart can become enlarged
Venous systems
Normally:
Arteries
Capillaries
Veins
Heart
Portal systems
With portal system:
Veins branch again into capillaries
portal vein
Hepatic portal system
Newly absorbed compounds are
brought to liver
Conservative: found in all
vertebrates
Renal portal system
From hind limbs to kidney, resorbing
portion of kidney circulation
All vertebrates except mammals