Transcript Phylogeny of respiratory pigments

Functions of circulation
To transport:
1. Solutes
- gases
- nutrients
- chemical wastes
- chemical signals- hormones
2. Heat - insects
3. Force
- use in locomotion (e.g. spiders, slugs)
- use in ultrafiltration across membranes
4. Immunity
5. Clotting
A version of proposed evolutionary relationships
between animal phyla
Poriphera
No tissues
Unicellular
organisms
Cnidaria
Multicellulariity
Radial
symmetry
Ctenophora
True tissue
organization
Platyhelmintha
Evolution of
Circulatory
systems
No body cavities
Bilateral symmetry
Body cavity
develops from
other cells
Have body cavities
and blood vascular
system
Body cavity
develops from
mesoderm
Nematoda
Annelida
Arthropoda
Mollusca
Echinodermata
Hemichordata
Urochordata
Chordata
Vertebrata
Comparative circulatory systems
Components of circulation system
1. Pump
2. Channels
3. Blood/Hemolymph
Methods of circulation
Circulation of external medium
in Poriphera and Cnidaria
(propulsion by cilia, flagella, or
muscle contraction)
Open circulatory
system of arthropods
and most molluscs
Closed circulation in annelids
and cephalopod molluscs;
respiratory surface may be
skin or gills
hemocoel
heart
heart
respiratory
surface
Open vs. closed systems
Closed
•Blood remains in vessels
•High pressure
•Regulate flow to each organ
•Return to heart rapid
•Found in:
vertebrates, echinoderms,
cephalopods* (why?)
annelids*
Open
•Blood directly bathes tissues
•Usually lower pressure
•Less regulated flow
•Return to heart slower
•Found in:
most arthropods, urochordates
most other molluscs
Vertebrate respiratory mechanisms
Efficiency of O2 extraction
Types of pumps:
Peristaltic
e.g. squirt; insect; worms
Contractile chamber
e.g. vert. branchial heart
Tube chamber with
separate muscles
e.g. vert. veins
Flow in rigid tubes
Flow in a rigid tube can
be described by:
Average flow velocity will
be flow volume rate Q
divided by the x-sectional
area
Q = Velocity
š r2
Poiseuille’s Law
Q = (P1-P2) š r2
8Lh
Q=P/R
Q is flow volume rate
(P1-P2) is pressure diff.
r is radius of tube
L is length of tube
h is fluid viscosity
Flow dynamics
Bernoulli’s theorem:
Energy = Pressure + Kinetic + Gravity
E=(pv)+(mgh)+(1/2mu^2
Where does the
energy go?
Flow dynamics
Bernoulli’s theorem:
Flow from high E to low E
(not high P to low P)
Energy = Pressure + Kinetic + Gravity
assume
flow rate
steady
(no other
path)
Vessels are not rigid tubes
compliance- (1/spring constant)
• Veins are volume reservoir and high
compliance. Terrestrials!! Stand up and you
might get a head rush, which is actually an
“out of head rush”. Compensated by
adrenergic fibers. If you prick me and I bleed,
do I not vasoconstrict?
• Arteries are pressure reservoir. Less
compliance. Smooth heartbeat. Keep pressure
relatively constant to not strain capillaries.
Also maintain efficiency of diffusion with
constant velocity.
The body plan of platyhelminths makes diffusion an
effective mechanism of transport.
S/V= 6 L2/L3
Fick equation:
J = k(Cs - Cx)
Only good when:
very small, very
thin, very inactive-or all three
What energy
drives this?
where J = quantity of a commodity moved per unit time
k = a constant related to how readily the commodity can move
Cs = concentration at the source
Cx = concentration some distance away from the source
A very simple distributing system: the
gastro-vascular system of Cnidaria
radial canal
Each canal is lined
with beating cilia
ring canal
Aequorea victoria,
Open circulation in insect
Low metabolism?
Pulsatile organs
Dorsal diaphragm
Nerve cord
septa
Insect circulation
Anterior dorsal aorta peristalsis
Accessory pumps for
antennae, legs, wings
External muscles assist filling
of dorsal heart (“suction”)
Typical crustacean circulation
THE ANIMAL OF THE DAY
Hagfish (Ph:Chordata; ?:Agnatha)
<2 feet
Why is it interesting?
• Unlike other chordates, hagfish possess several hearts.
• A systemic heart & accessory hearts to help with venous return.
• Mostly closed circulation, but some sinuses w/o endothelium.
• As much as 80% of O2 through skin.
• Systemic heart is myogenic, & not innervated.
• Blood pressure is quite low.
THE ANIMAL OF THE DAY
Hagfish (Ph:Chordata; ?:Agnatha)
Amphibian (bullfrog, Rana)
What
happens
when the
frog dives?
separate at high
flow rates
* crocodiles dive too???
S = O2 saturation
Control of heart rate
1. Neurogenic hearts- beat initiated by CNS
- annelids, crustaceans, arachnids
2. Myogenic hearts - they got rhythm
- vertebrates, most molluscs, some insects
- are modulated by autonomic CNS
sympathetic v. parasympathetic input
(noreprinephrine v. acetyl choline)
How change amount transported?
The volume transported over time (Q)
can be changed by:
Q=f•V
1. Increased rate of pumping (f). e.g birds, mammals
2. Increase volume (V) for each stroke of the pump.
e.g. fish
3. Increased carrying capacity of the fluid
(i.e. blood).
Each of these can account for individual differences or species diff.
Heart rate decreases w/size
mammals
Heart rate decreases w/ mammal size
log scale
mammals
Why? (slope)
Other methods?
(predict slope)
logarithmic relationship:
r=k•Mb
(b = slope = –.25)
log r = log k • b(logM)
log scale
Heart mass directly proportional to body mass
(0.6%) in mammals
Stroke volume is
proportional to body
mass in mammals,
and can not account
for phylogenetic
variation in
metabolism.
h.m. = k • b.m 0.98
Heart rate v. Stroke volume
* What else is changing?
*
Lower volume Q compensated by carrying capacity
Hemocyanin is an
O2 carrying pigment
found in many
invertebrate bloods.
Unlike Hb, it is
dissolved in the
hemolymph.
The total cross-sectional
area of the vessels
increases with distance
from the heart.
Q = Velocity
š r2
Why?
Consequently, the
velocity of flow
decreases, and then
increases after passing
the capillaries.
Blood pressure decreases away from heart
As x-sectional area
increases, pressure
decreases in arterioles.
When x-sectional area
decreases again in venules,
the pressure does not
return due dissipation due
to friction w/ capillaries.
Distribution of blood
Control of cardiovascular systems
Baroreceptors
- atrial tonic receptors cause reflexive compensation
Chemoreceptors (CO2, O2, pH)
- if CO2 increases or O2, pH decrease, then slow heart
if not breathing (how maintain B.P.?)
Stretch receptors
- increased atrial volume changes hormones to inc. urine
Thermoreceptors
Sympathetic v. parasympathetic centers & signals
Feedback control in circulation
Control of capillaries
Nervous system:
- Sympathetic norepinephrine to a-adrenergic receptors.
- Parasympathetic ACh release.
(effects on heart rate?)
Local control:
NO; peptides; histamine
Adaptation to posture changes
tree snakes have tight
skin and anteriorly
displaced hearts
ground snakes will pass
out if held upright too
long
Pressure in humans
Giraffe (Ph:Chordata, Ge:Giraffa)
Lowering head could
result in aneurysm.
Giraffe (Ph:Chordata, Ge:Giraffa)
• lower heart pressure
& vasodilation
• tight skin around legs
prevents pooling
• prehensile tongue
What color?
Don’t worry, sea slugs also have the same
problem
Exercise
1) Vasodilation in muscles; reduce
resistance, reflex increases cardiac
output.
2) Increased heart rate and force;
stroke vol. in fish.
3) Release RBCs from spleen.
Diving
Diving verts need to limit consumption of O2.
If CO2 builds up, and lungs not stretched, then
peripheral vasoconstriction -> reduced heart rate.
(vice-versa if lungs stretched)
Bradycardia shown by forced dive animals.
Not in free diving animals, unless chased.
Distribution of blood flow
Relative osmotic pressure & exchange
Ultrafiltration.
protein colloids
regain some fluid
not quite even; lymph
Phylogeny of respiratory pigments
Respiratory Pigments