Spleen
Vertebrate hearts
• White pulp – macrophages, monocyte storage
• Red pulp - (RBC) storage, and prod’n (in nonmammals)
• Pericardial cavity – division in coelum
• Endocardium = endothelium of blood
vessels
Fig. 19.1. Spleen.
Artery
smooth
muscle
elastic tissue
Arteriole
endothelium
elastic tissue
smooth muscle
Arteries contain
connective tissue
with elastin and
collagen
Artery
Vessel walls
endothelium
endothelium
Capillary
Artery
Vein
Vein
smooth muscle,
elastic fibers
endothelium
valve
Veins include
valves
Vein
1
Veins
Large arteries
• Elastic recoil from
arteries drives flow of
blood during diastole
Systole
• Most of the blood volume is in venous
system (60-70%) - resevoir
• Blood volume is variable
• Arteries temporarily
expand and hold
pumped blood
Diastole
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
2
Ancestral vertebrate pattern
Dorsal Aorta
Venous development
Paired dorsal Aortae
Internal Carotid
6 VI 5
V
4
IV 3 III
2
II 1 I
• Sinous venosus, hepatic portal system
Ventral Aorta
Heart
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
3
Fish circulation

Aortic arches
In fish, the aortic arches (AA) are the
afferent and efferent branchial arteries
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
4
Many tetrapods have incomplete
separations
•
•
•
•
Amphibians
Dipnoi
Ancestral crossopterygii
Reptiles
Lungfish aortic arches
facing
A fish with
pulmonary
circulation
Often not using lungs!
In other fish,
swim bladders
supplied from
dorsal aorta
Most blood in systemic
Shunting a must
Aquatic
2
3
4
5
6
On land
Amphibian circulation
Lungfish heart


Has incomplete separation of both rt. &
lt. atria; and rt. & lt. ventricles
Yet two ‘streams’ are separate


• Metamorphosis – heart moves towards lungs
• AA’s are ‘traditional’ tetrapod: 3,4,6 (frog)
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
5
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
6
Frog heart
Frog heart
Ventricle
contraction
Frog spiral valve
• Spiral valve in conus arteriosus
Ventral aorta
shortened
to truncus
arteriosus
Reptile circulation
• Truncus arteriosus
has three trunks
LS
RS
P
7
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
Crocodilia heart
• Ventricles divided
• Crocodiles have
foramen of Panizza
connecting rt. and lf.
systemic
• Lf systemic can receive
rt. ventricle blood
Crocodilia heart
• Using lungs
valve
higher
pressure
– Foramen of Panizza
allows Ox. blood into
left systemic
Left to right shunt
8
Bird
Crocodilia heart
Mammal
• Systemic arch is one-sided in endotherms
lower
pressure
Cog
• Diving– F. of P. allows mixed
blood to flow into
right systemic
Right to left shunt
p.618
Human heart development
Adult mammal circulation
One-way flow
in early
development
9
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 lt atrium goes through
foramen ovale to rt atrium
10
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
11
Portal systems
Hepatic portal system
• Newly absorbed compounds
are brought to liver
• With portal system:
Veins branch again into capillaries
portal vein
• Conservative: found in all
vertebrates
Renal portal system
• From hind limbs to kidney, resorbing
portion of kidney circulation
• All vertebrates except
mammals
12