2. Flashcards
How do seals optimize oxygen during a dive?
- seals can consciously program where their blood flows
- needs to hold breath for a long time during a dive, but make sure tissues get oxygen
- scientists monitored their blood flow, and notices that the change for optimal flow for diving occurred before diving, thus likely consciously
- human bodies do this passively
Components of Circulatory system
- circulatory system move fluids by increasing the pressure of the fluid in one part of the body
- fluid flows through body, “down” pressure gradient
THREE MAIN COMPONENTS ARE NEEDED:
1. Pump or propulsive structures
2. Fluid that circulates through the system
3. System of tubes, channels, or spaces (vessels)
Single Pump
- One way flow is controlled by valves present
- Has a contractile chamber
- The contractile chamber creates a pressure gradient that opens and closes valves, and blood flows unidirectionally through the vessel
Types of Pumps
There are three pumps that could be present in the circulatory system:
Contractile Chamber:
- the heart is composed of chambers which as individual pumps
(())
Skeletal Muscle:
- may contract to propel fluid
- plays important role in returning blood from lower extremities
- speed and pressure are lost as moves through the vessels, therefore, skeletal muscles are wrapped around vessels and when they contract (walking) it helps move blood upwards ((||))
Pulsating Blood Vessels:
- tube-like hearts in invertebrates and early vertebrate embryos (or heart embryos) (||)
**good photo pg 21
Heart/circulatory structure can vary in
- heart structure
- number of hearts, number of chambers
- snake hearts get bigger when needed
- zebrafish hearts can regenerate
of Chambers
- Bony dish - arranged in series
Amphibian - 3 chambers
Non-crocodilian reptiles - 5 chambers
Fish Heart (path)
Sinus venosus –> atrium –> ventricle –> bulbus arteriosus
Fish Heart (Info)
- chambers are in organized series
- serial contractile chambers
(Sinuous venosus, atrium, ventricle, bulbus arteriosus) - a simple one-way circuit
- there is no pulmonary circuit because fish do not breath through lungs
- valves are passive
- open and close according to pressure differences/gradient
(fluid into space, build up pressure, eventually opens valve, flows out) - ensure unidirectional blood flow
- blood flows into spongy myocardium in ventricle
Spongy Myocardium - patchy area in ventricle - receives oxygen from blood flowing through ventricle, to oxygen heart (spongy - not as compact as other hearts) - in teleosts, bulbus arteriosus is volume and pressure reservoir (called conus arteriosus in cartilaginous fish)
Amphibian Heart (pathway)
sinus venosus –> right atrium –> ventricle –> conus arteriosus –> pulmonary artery –> lungs–> pulmonary vein–> left atrium –> ventricle –> conus arteriosus –> systemic arteries
Amphibian Heart (Info)
*two atria, one ventricle
- ventricle is main contractile unit of the heart
- the atria can contract to a less extent, providing blood from an oxy or deoxy source
*Atria
Left: receives oxygenated blood from lungs/pulmonary veins
Right: receives deoxygenated blood from system circulation through sinus venosus; oxygenated slightly from skin
*Ventricle
- oxy- and deoxy- kept separate
–> TRABECULAE - lines of contractile tissue in ventricle that helps separate deoxy and oxy
–> there is risk of mixing, but this heart still fits the frogs needs the best
- sends blood to the conus arteriosus
*Conus arteriosus
- receives blood from ventricle
- moves blood to pulmocutaneous (pulmonary artery), or to systemic arteries (arteries that will supply blood to the rest of the body)
- SPINAL FOLD - keep blood separate in conus arteriosus
Why does the frog permit/withstand mixing of deoxygenated blood?
- the heart is built/structured to minimize mixing (trabeculae, spiral fold)
- the frog can exchange o2 and co2 in lungs and through skin
–> deoxygenated blood running through system can pick up oxygen
Turtle, Lizard and Snake Hearts (info)
** non-crocodilian
* 5 - chambered heart
- two atria + (3-chambered) ventricle
- Conus arteriosus has disappeared
*Ventricle split into three different chambers
Cavum Venosum: leads to systemic arteries
- receives from right atrium (deoxygenated), sends to cavum pulmonale
- receives from cavum arteriosum, sends to systemic arteries
Cavum Pulmonale - leads to pulmonary artery
Cavum Arteriosum - receives from pulmonary vein and left atrium, sends to cavum venosum
Turtle, Lizard, Snake (pathway)
- 5-chambered heart
sinus-venosus –> right atrium –> cavum venosum –> cavum pulmonale –> pulmonary artery –> lungs –> pulmonary vein –> left atrium –> cavum arteriosum –> cavum venosum –> systemic arteries (left or right aorta) –> systemic body
Shunting in Reptile Hearts
- reptiles tend to go underwater for long periods of time, thus need to maximize oxygen circulation to important places
- functions of the two shunts are debated
- mostly see shunts as adaptions
R-L SHUNT - associated with diving
- circulates low deoxy blood back into system
- blood flows right atrium to right aorta
L-R SHUNT - associated with oxygenating the heart
- sending oxy blood into pulmonary circuit because the pulmonary circuit returns oxygen quicker to the heart blood vessels
- blood flows left atrium to pulmonary artery
Birds & Mammals Circulatory Circuits
birds and mammal’s circuits are very similar
- 2 atria, 2 ventricles
- separated pulmonary and systemic circuit
- differences, ex. birds would be optimized for flight
4 systems have evolved to supply oxygen to hearts of animals
- mammalian heart - coronary vessels
- most teleost - spongy myocardium
- some fishes - vessels and spongy myocardium
- some octopuses - vessels, and mixing of blood from the ventricle to the coronary vessels
Mammal Heart Oxygen Supply
- the heart is an active muscle demanding large amounts of O2, and nutrients
- the mammalian heart is compact - really dense network of myocardium (myocardial cells packed closely together)
- blood from ventricles cannot perfuse cardiac muscles
- coronary arteries supply blood to heart (myocardium)
–> profuse the whole heart - has coronary vessels
- compact myocardium
- outside of the heart is covered in vessel
- blood pumped through heart does not oxygenate
Most Teleost Heart Oxygen Supply
- has spony myocardium
–> directly oxygenated from blood flowing through ventricle
–> blood flowing through ventricle, profusion through myocardiocytes/myocardium, has exchange - no coronary vessels
- ancestral heart
- blood not well oxygenated (deoxy through heart to gills, gills to system, system to heart)
- underwater, different ways to profuse, evolved on land to have more efficient ways (coronary vessels)
Some Fish Heart Oxygen Supply
- outer layer compact
–> require coronary arteries to supply blood - inner layer spongy myocardium
Some Octopuses Heart Oxygen Supply
- myocardium of mixed structure with blood flowing from lumen into coronary veins
- from lumen to coronary veins
- mixing of blood from the ventricle to the coronary vessels
- octopi can have more than one heart
Myocardial Cells
Main contractile unit of heart, able to function as one coheasive unit
Mammalian Cardiac Cycle
- movement from the atria to ventricles relies on pressure gradients
- contraction of the ventricles actively moves blood to the aorta or pulmonary artery
- works as a cohesive unit
- atrial contraction, ventricle contraction, valve opening and closing must all work cohesively in the right order
Two Phases of Mammalian Cardiac Cycle
SYSTOLE
- contraction
- blood is forced out into the circulation
DIASOTLE
- relaxation
- blood enters the heart
Definition:
vein and artery
Vein - blood vessel returning to heart
Artery - blood vessel leaving/leading away from heart
Human Heart (pathway)
vena cava –> right atria –> right atrioventricular valve –> right ventricle –> pulmonay valve –> pulmonary trunk (artery) –> lungs (pulmonary circuit)
–> pulmonary veins –> left atrium –> left atrioventricular valve –> left ventricle –> aortic valve –> systemic aorta –> systemic circuit