05 - Hearts and Circulatory Systems

closed circulatory - blood vessel

serious of vessels are all connected

closed circulatory system - circulatory fluid

blood

Blood is separate from the extracellular fluid (ECF)

Blood Flow Pathway - closed circulatory system

Heart → Arteries → Capillaries → Veins → Back to the Heart

closed circulatory system - single circuit

fish

closed circulatory system - multiple circuit

advanatage of closed circulatory system

being high pressure systems - blood pressure can be kept high leading to high levels of blood flow to tissues and therefore high levels of oxygen and nutrient delivery.

allow for blood to be directed to specific organs - it is possible to regulate

blood flow to individual organs; increasing or decreasing flow as required

open circulatory system - circulatory fluid

haemolymph - can be considered to be a mixture of blood and extracellular fluid. I

open circulatory system - blood vessels

blood vessels (i.e., arteries, capillaries and veins) do not form a complete enclosed circuit starting and ending at the heart.

the haemolymph is pumped from the heart into arteries. It is then “dumped” into the body cavity or sinuses in the tissues before being picked up by veins and returned to the heart.

open circulatory system - pressure system

low pressure systems

that blood flow to organs is not as fast or efficient as seen in closed circulatory systems.

parts of the heart

two ventricles (left and right) and two atria (left and right).

purpose of left side of heart

high pressure pump that pumps oxygenated blood to the systemic tissues.

purpose of right side of heart

low pressure pump that pumps deoxygenated blood to the lungs

left atria

Oxygenated blood returning to the heart from the lungs enters the left atria

how does oxygynated blood enter the left atria

pulomnary veins

what happens to the blood after left atria

It then moves through an atrioventricular (AV) valve into the left ventricle. (Blood in)

right atria

Deoxygenated blood returning to the heart from the systemic circulation (all organs not including the lungs) enters the right atria

how does deoxygynated blood enter the right atria

superior and inferior vena cava.

what happens to the blood after right atria

moves through an atrioventricular valve into the right ventricle.

left ventricle

Oxygenated blood leaves the left ventricle

right ventricle

Deoxygenated blood leaves the right ventricle t

how does Oxygenated blood leave the left ventricle

through a semilunar valve and enters the aorta (Blood out)

how does Deoxygenated blood leave the right ventricle

hrough a semilunar valve and enters the pulmonary arteries (Blood out)

atrioventricular valves

valves that separate the atria and the ventricles

semilunar valves

separate the left ventricle from the aorta and the right ventricle from

the pulmonary artery.

pathway The Human/Mammalian Circulation

Deoxygenated blood → Superior and Inferior Vena Cava → Right Atria → Right

Ventricle → Pulmonary Arteries → Lung → Oxygenated Blood → Pulmonary Veins →

Left Atria → Left Ventricles → Aorta → Systemic Tissues → Deoxygenated Blood

how does mammalian fetus receive blood

from the placenta

blood pathway for fetal

From the placenta, blood flows, via the umbilical vein, into the right atria of the fetus.

what do fetals breath

amniotic fluid

why is blood shunted away from lungs

fetal lungs breathe amniotic fluid and not air

thus lungs not involved in oxygen exchange

thus no point in sending blood to lungs

how is blood shunted away from lungs

2 ways

foramen ovale and ductus arteriosus

shunted away from lungs - foramen ovale

blood flowing into the right atria (from the umbilical vein) is not sent to the right ventricle

it is shunted through a “hole-in-the-heart” called the foramen ovale into the

left atria.

shunted away from lungs - ductus arteriosus

if blood isnt shunted through foramen ovale

(moved from right atria to right ventricle to pulmonary artery)

it gets shunted through the ductus arteriosus into the aorta.

The ductus arteriosus is a hole between the pulmonary artery and the aorta.

what happens to oramen ovale and the ductus arteriosus at birth

close immediately at birth due to a complex series of changes in blood pressure and blood flow resistance that are triggered once the lungs start to breath air rather than amniotic fluid.

cephalopods - circulatory pathway

3 hearts

deoxygenated blood is pumped via two branchial hearts across the gills where it is oxygenated

Oxygenated blood then flows to the systemic heart which pumps it to the systemic circulation.

the branchial hearts are the equivalent to what of the mammalian heart

right side

pumping deoxygenated blood to the gas exchange organ – the gills for cephalopods; lungs for mammals

the systematic hearts are the equivalent to what of the mammalian heart

left side

pumping oxygenated blood to the systemic tissues

Why are both the oxygenated and deoxygenated blood blue of cephalopod

• Unlike mammals (which use iron-based hemoglobin, making blood red), cephalopods use copper-based hemocyanin to transport oxygen.

• Deoxygenated hemocyanin = Darker blue

• Oxygenated hemocyanin = Lighter blue

afferent

inflow

efferent

outflow

examples of Cephalopods

squid and octopi

structure of fish heart

4 chambers in series (i.e., one following the other)

sinus venosus

atrium

ventricle

bulbus arteriosus

fish circulatory system path way

Venous (deoxygenated) blood enters the heart through the sinus venosus.

Blood then flows through the sinoatrial valve into the atrium (a very thin-walled chamber).

Blood then passes through the atrioventricular valve into a muscular ventricle.

Finally blood moves through the bulbal valve into the bulbus arteriosus

contractile force of fish circulatroy system

The atrium and the ventricle are both contractile but most of the contractile force arises from the ventricle.

Windkessel vessel

This means that it expands (fills with blood and bulges outward) when the heart is contracting and then collapses back into its initial “shape” when the heart is relaxing. This helps force blood through the arteries when the heart is relaxing

bulbous arteriosus functions as windkessel vessel

Circulation in Gill pathway

Deoxygenated blood from the tissues (systemic circulation) returns to the heart through the venous system.

It is then pumped through the ventral aorta (VA) to the gills where it is oxygenated.

Oxygenated blood leaves the gills via the dorsal aorta (DA) and flows into the systemic circulation.

The circulation is therefore a single loop – heart to VA to gills to DA to systemic circulation (arteries then veins) and then back to the heart.

heart → ventral aorta → gills → dorsal aorta → systemic circulation → heart

in fish circulatory system blood must be pumped in how many capillary beds

Blood must be pumped across two capillary beds – capillaries in the gills and capillaries in the systemic circulation.

Therefore, the heart must generate sufficient pressure to drive the blood through the entire circuit while simultaneously having a low enough pressure to prevent pressure-induced damage to the delicate gill tissue.

which circulatory system does the lung fish resemble to

more of a mammel than a fish even though its a fish

Circulation in the Lungfish

Deoxygenated blood returns to the heart from the tissues (i.e., the systemic circulation).

It is then pumped through the gills to a pulmonary artery (PA) and then into the lungs where it is oxygenated.

It then returns to the left side of the heart.

It is then pumped through the gills to the dorsal aorta (DA)

then to the systemic circulation (tissues) where it supplies oxygen to the tissues and becomes deoxygenated

It then returns to the right side of the heart.

right artria → right ventricle → gills → pulomnary artery → lungs → left atria → left ventricle → gills → dorsal aorta → systematic circulation →

simmilarty and differences between lung fish and mamalian circulatory system

differences:heart is not completely divided like a mammalian

simmilarity: The right side of the heart receives deoxygenated blood from the systemic circulation and the left side of the heart receives oxygenated blood from the lungs.

role of gills in lung fish circulatory system

the gills play very little role in gas exchange (i.e., O2 uptake from the water or CO2 excretion into the water) since they are much reduced in size

Amphibian Heart

3 chambers

left atrium, right atrium, single ventricle

Amphibian circulatory system

Deoxygenated blood from the tissues enters the sinus venous (part of the venous system)

Then flows into the right atria.

It enters the ventricle and then the conus arteriosus.

This deoxygenated blood then flows through the pulmocutaneous arteries to the lungs and the skin.

Within the lungs and skin, blood picks up oxygen (becomes oxygenated) and also loses CO2

Oxygenated blood from the lungs returns to the left atria via the pulmonary vein.

Then enters the ventricle and the conus arteriosus before moving through the systemic arteries to the tissues (systemic circulation)

where it gives up oxygen to the tissues and picks up CO2 (a waste product of metabolism).

tissue → sinus venous → right atria → ventricle → conus arteriosus → pulmocutaneous arteries → lungs/ skin → pulmonary vein → left atria → ventricle → conus arteriosus → systemic arteries → systemic circulation

how doesnt oxygenated and deoxygenated blood mix within the ventricle

very little mixing occurs. There are anatomical features of the ventricle and the conus arteriosus that prevent this. In addition, slight differences in the timing of contraction of the right and left atria also help prevent this

oxygynated blood = higher con vol %

deoxygynated = lower

Reptilian Hearts - non crocodiles

two atria and two ventricles

the ventricles are not completely divided (i.e., there is a connection between

the left and right ventricle such that blood can move between the two ventricles

three blood vessels that arise directly from the ventricles

pulmonary artery → transports blood to the lungs

two aorta → transport blood to the systemic circulation.

reptilian - circulation non crodile

Deoxygenated blood from the tissues enters the right atrium.

It will then move into the ventricles and ultimately be pumped to the lungs.

Oxygenated blood from the lungs enters the left atrium.

It will then move into the ventricles

Then be pumped through the aorta to the systemic circulation.

In the turtle, the left aorta actually receives deoxygenated blood rather than oxygenated blood.

Reptilian Hearts - crocodiles, parts, vessels, valves

two atria and two ventricles

The ventricles are completely divided into a left ventricle and a right ventricle

Blood cannot move from one ventricle into the other ventricle

pulmonary artery that leaves the right ventricle → deoxygenated blood to the lungs.

left aorta (systemic arch) that leaves the right ventricle → when open it carries

deoxygenated blood to the systemic tissues

right aorta (systemic arch) leaves the left ventricle

valve that separates the right ventricle from the left aorta.

valve that separates the left ventricle from the right aorta

connection between the right aorta and the left aorta → Foramen of Panizza.

Blood Flow from the Crocodilian Heart during Normal Breathing

• Low resistance in the pulmonary artery (PA) → Blood easily flows to the lungs.

• Deoxygenated blood from the right ventricle (RV) → into the pulmonary artery (PA) → reaches the lungs for oxygenation.

• Pressure in the right ventricle (RV) is lower than in the left aorta (LA) → Keeps the RV-to-LA valve closed, preventing mixing.

• Oxygenated blood from the left ventricle (LV) → flows into the right aorta (RA) and (to a lesser extent) into the left aorta (LA) through the Foramen of Panizza.

Crocodilian Heart during Normal Breathing simmilarity to humans

• Right side pumps deoxygenated blood to the lungs.

• Left side pumps oxygenated blood to systemic circulation.

• Main difference: Crocodiles have two aortas (RA & LA), while humans have one.

Blood Flow from the Crocodilian Heart during Diving

• crocodile doesnt breathe = Lung and pulmonary artery (PA) blood vessels constrict, increasing resistance to blood flow.

• Less or no blood reaches the lungs, leading to a pressure build-up in the right ventricle (RV).

• Pressure in the right ventricle (RV) exceeds that in the left aorta (LA) → Opens the RV-to-LA valve.

• Blood that should have gone to the lungs is redirected into the systemic circulation via the left aorta (LA).

• Deoxygenated blood is recycled back into the body instead of being reoxygenated.