Download Bio 4850.8Cardiovascular

Cardiovascular physiology
Oxygen delivery and uptake
Circulatory systems
Gastrovascular cavity
thin body walls
flagella stir fluid
Fig. 9.1
Open circulatory system
hemolymph
g volume
large
low pressure
most invertebrates
Closed circulatory system
blood
small volume
high pressure
vertebrates
some invertebrates
Bulk flow of fluid in animals that lack a circulatory system
Fig 9 5
Fig.9.5
Types of circulatory systems
1 OPEN CIRCULATORY SYSTEM
1.
(most invertebrates)
Low pressure (< 1.5 kPa)
High volume (30% body vol.)
Sl
Slow
velocity
l it
pump + vessels
Fig. 9.7
Insects
Open circulatory system
multiple hearts
one
o
e heart/segment
ea t/seg e t
peristalsis
hemocoel
Fig. 9.9
Most invertebrates have
open circulatory
systems
but:
Cephalopods (Molluscs)
and
Oligochaetes (Annelids)
have a closed
circulatory system
Fig. 9.3
2. CLOSED CIRCULATORY SYSTEM
(cephalopods, vertebrates)
High pressure (>12 kPa)
Low volume (5-10%)
High velocity
Distribution regulation
g
Ultrafiltration
Lymphatic system
Fig. 9.10
Circulation
C
cu at o in birds
b ds and
a d mammals
a
as
respiratory and systemic circulations
in parallel
F
Four
chambered
h b d heart
h t
Two completely
p
y separate
p
circuits
pulmonary circuit
(low pressure)
systemic circuit
(high pressure)
Fig. 9.37
Cardiovascular system in water-breathing teleost
Fig. 12.16 Eckert
Cardiovascular system in air or water-breathing teleost
The African lungfish
Fig. 12.16c Eckert
Circulatory systems in air-breathing fish, amphibians, and reptiles
Air-breathing organ (e.g. lung) arranged in parallel to other tissues
Yet the heart is a four chambered pump only in Birds and Mammals
Comparative anatomy of vertebrate hearts
Fish heart: 1 atrium + 1 ventricle
[sinus venosus]
atrium (1)
ventricle (1)
[bulbus or conus arteriosus]
chambers arranged in series
Amphibian heart: 2 atria + 1 ventricle
[sinus venosus]
right
i ht atrium
ti
to ventricle
left atrium
to ventricle
conus arteriosus with spiral fold
systemic arteries (oxygenated blood)
pulmocutaneous artery (deoxygenated)
Cardiovascular system in amphibian
Non-crocodilian reptiles
2 atria
t i + 2(3) iincompletely
l t l separated
t d ventricles
ti l
Fig. 9.16
Crocodilian reptiles - 2 atria + 2 completely separated ventricles
Non-Crocodilian Reptile
partial ventricular septum
RA contracts earlier than LA
earlier flow in pulm.artery than systemic arches
…diving turtles…
…varanid lizards…
Mammalian circulation
Fig. 12.22
Eckert
adult
fetal heart
Mammalian fetal circulation
Where is blood oxygenated? Where does oxygenated blood enter heart?
pulmonary
y artery
yg
go? How can oxygenated
yg
blood be sent
Where does blood in p
to brain and other systemic tissues?
Solutions?
Fetal
circulation
FetalÆ Postnatal circulation
PlacentalÆ Pulmonary Gas Exchange
At birth:
- umbilical vessels constrict
↑ peripheral resistance Î ↑ peripheral blood pressure
↑ Psystemic Î ↓ flow to R atrium
- umbilical venous flow ceases
ductus venosus closes
- lungs inflate
↓ pulmonary resistance Î ↑ blood flow to lungs
↓ Ppulmonary Î ↑ flow to L atrium
LA pressure > RA pressure
foramen ovale closes
fusion of septal leaves (several days)
aortic pressure > pulmonary a. pressure
blood flow in ductus arteriosus reverses
high Po2 in ductus arteriosus
vasoconstriction of d. arteriosus
progressive constriction complete 1-2 days
Effects of gravity on blood pressure and the circulatory system
ΔP = ρ g Δh
ΔP diff
difference in
i pressure (hydrostatic)
(h d t ti )
between two points in a fluid column
ρ ((rho)) densityy of the fluid
g acceleration due to gravity
Δh difference in height of the fluid column
Fig. 9.30
Cardiovascualr challenges in
a giraffe
g
Changes in posture
standing
feeding/drinking
How to mainten blood flow to the head
How to prevent edema in the feet
Vasodilation
Vasoconstriction
Anatomical adaptations
Fig. 12.33 Eckert
Cardiovascular system in
a giraffe
Cardiovascular challenges
in a giraffe
Solutions?
Fig. 9.43
Fig. 9.36 Net filtration pressure along a capillary