CVA: CIRCULATION

Is the lymphatic system pumped by the heart?

No

What else does fluid mvmt also regulate?

Temp and pressure

Arteries

Carries blood AWAY from heart

MOST carry O2-rich blood

Elasticity > veins

Start off big then thins out

Arterioles

v small arteries

Viens

Carries blood towards heart

MOSTLY carries O2-poor blood

1-way valves control flow

Start off small then thickens as you approach the heart

Venules

v small veins

Capillaries

tiny ass vessels b/w arteries and veins; sites of exchange

1x Circuit

Once through heart per circuit (most fishes)

(Heart→gills→systemic→Heart)

2x Circuit

twice through heart per circuit (amniotes)

Includes pulmonary circuit to oxygenate blood before systemic circuit

Lungfishes, amphibians, and some reptiles have

intermedite-type systems

Aortic arches

paired arteries immediately after heart (and ventral aorta)

Aortic arches are numbered I to IV based on embryo with 6 arches, but Arch I is almost always

lost

Afferent branchial arteries

enter gills

Efferent branchial arteries

exit gills

W/in sharks, the 1st arch is reduced to

spiracle

Arch II supplies

internal carotid (to brain)

Arch II-VI supplies

the rest of the body

Arch I and II are lost in

amphibians

Salamanders

Arches III-V carry external gills

Arch VI forms pulmonary artery (to lungs) (except in neotenic taxa like Necturus)

III and IV: form common carotid artery (to head)

Frogs

III-VI form gills in larvae; gills lost along with all of V

III: head

IV: body

VI: pulmonary circuit

Arches tend to become asymmetric in

amniotes

Vertebrate hearts probably originated as contractile blood vessel as in

lacelets

What’s the valve(s) between the Atrium and Ventricle?

Atrioventricular valve(s)

The 4 seried chambers of the heart:

Sinus venosus → Atrium → Bulbus cordis (embryo) or conus arteriosus or bulbus arterious (adults)

What do valves create?

1 way flow; permit aspiration filling of chambers

Hagfish hearts are

3 chambers (no bulbus/ conus arteriousus) and are not controlled by nerovous impulse

Lampreys hearts are

innervated with a basic 4 chamber plan that includes the bulbus arteiousus

Chondrichthyes' hearts are

4 chamber plan incl. conus arteriosus (muscular)

Osteichthyes hearts are

4 chamber plan + bulbus arteriosus (nonmuscular)

Lungfish hearts have

Interatrial and interventricular septum, which partially divide chambers and permits partial separation of oxygenated and deoxygenated blood

When breathing air, left side carries

MORE O2

When breathing air, right side carries

LESS O2

Spiral valve

helps separate O2-rich and O2-poor

MOST amphibian hearts are

3 chambered (2 atria, 1 ventricle)

Amphibians w lungs have

interatrial septum

Amphibian hearts separate O2-rich vs O2-poor via

trabeculae w/in ventricle

Turtles and squamates heart consist of

5 chambers: 2 atria, 1 ventricle (3 interconnected compartments);

Ventricle divided by muscular ridge, Cavum pulmonale, Cavum venosum, Cavum ateriosum

Croc hearts are

o4 chambers: 2 atria, 2 ventricles;

Foramen of Panizza connects left and right systemic arches; and VALVES control blood flow, separate O₂-rich and O₂-poor blood

Turtle and croc have

right-to-left shunt when diving

Birds and mammal hearts are

4 heart chambers: 2 atria + 2 ventricles;

Sinus venosus greatly reduced, especially in mammals; Conus arteriosus splits during development, forms pulmonary trunk and single aortic trunk

Bird and mammal hearts arose

independently…4 chambered hearts are CONVERGENT evolution

For birds and mammals, L/R sides of heart are

completely separated after birth, separating O2-level differing blood

Blood vessels can act as heat blocks or radiators to maintain

body temperatures (vasodilation vs vasoconstriction)

Counter current exchange MAXIMIZES

heat transfer

Carotid rete

Regulates brain temp by cooling incoming blood

Cetaceans

artery-vein networks retain body heat