Regents Biology

37.1 – The Circulatory System

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§  Compare and contrast open and closed circulatory systems

§  Examine how the circulatory system evolves with animal complexity

Objectives

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Exchange of materials §  ALL organisms must

exchange materials with their environment.

§  Cells exchange substances across membrane.

§  Easy for unicellular organisms! Substances simply diffuse across.

§  How about multicellular organisms?

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Circulatory system §  ensures that no substance must diffuse very far

§  What needs to be transported: -  nutrients -  respiratory gases (O2,

CO2) - waste (water, salt,

nitrogenous wastes) -  protective agents

(white blood cells, antibodies) and blood-clotting agents

-  regulatory molecules (hormones)

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§  Read “Open and closed circulatory systems” and answer review question 1

§  Read “Single- and double-loop circulation” and answer review question 2

§  Spend a few minutes discussing with your partner about what you just read.

Jigsaw

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In animals with many cell layers… The circulatory system has 3 basic components:

§  circulatory fluid (blood)

§  tubes (blood vessels)

§  muscular pump (heart)

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OPEN circulatory system §  in many invertebrates

(insects, arthropods, mollusks)

§  no separation between blood and interstitial fluid

§  Hemolymph

§  heart(s) contract to pump hemolymph into sinuses, relax to draw hemolymph back

§  little pressure!

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CLOSED circulatory system §  in some invertebrates

(earthworms, squid, octopuses)

§  in vertebrates §  blood confined to

vessels and separate from interstitial fluid

§ more pressure! § material diffuses

between blood vessels and interstitial fluid

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Evolution of Vertebrate Circulatory System

A

2 chamber 3 chamber 3 chamber 4 chamber

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Evolution of 4-chambered heart §  increase body size §  endothermy §  flight §  all result in higher metabolic rate,

greater need for energy, O2, waste removal

§  endothermic animals need 10 times more energy than animals of comparable size; thus, need to deliver 10 times more fuel and O2 to cells

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§  Describe the structures of the circulatory system §  Describe the flow of blood in the circulatory system §  Compare and contrast the 3 types of blood vessels §  Discuss common causes for heart diseases

Objectives

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The Heart §  enclosed in

pericardium (a protective sac of tissue)

§  thick layer of muscle called myocardium makes up wall of heart

§  myocardium contracts to pump blood

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The Heart §  septum divides the

heart into right and left sides

§  4 chambers – 2 atria and 2 ventricles

§  upper chamber (atrium) receives the blood

§  lower chamber (ventricle) pumps blood out of the heart

How Heart Pumps Blood http://www.youtube.com/watch?

v=JA0Wb3gc4mE

§  Blood enters heart through atria

§  right ventricle pumps oxygen-poor blood from heart to the lungs (pulmonary circulation)

§  In the lungs, oxygen is absorbed. Oxygen-rich blood returns to left atrium.

§  Oxygen-rich blood is pumped by left ventricle to the rest of the body (systemic circulation)

Right Ventricle

Right Atrium

Left Atrium

Inferior Vena Cava Vein that brings oxygen-poor

blood from the lower part of the body to the right atrium

Tricuspid Valve Prevents blood from flowing back into the right atrium after it has

entered the right ventricle

Pulmonary Valve Prevents blood from flowing back into the right ventricle

after it has entered the pulmonary artery

Pulmonary Veins Bring oxygen-rich blood from each of

the lungs to the left atrium

Superior Vena Cava Large vein that brings oxygen-poor blood from the

upper part of the body to the right atrium Aorta Brings oxygen-rich blood from the left

ventricle to the rest of the body

Pulmonary Arteries Bring oxygen-poor blood to

the lungs

Aortic Valve Prevents blood from flowing

back into the left ventricle after it has entered the aorta

Mitral Valve Prevents blood from flowing back into

the left atrium after it has entered the left ventricle

Left Ventricle

Septum

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Heartbeat

§  each contraction begins in the sinoatrial (SA) node in the right atrium

§  pacemaker cells §  atria contracts, blood from atria flows into ventricles §  ventricles contract, blood flows out of the heart

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter22/

animation__conducting_system_of_the_heart.html

§  carry blood from heart to tissues

§  thick walls §  narrow

§  1-cell thick wall. Advantage?

§  carry blood to heart

§  thinner walls §  wider diameter

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Exercise

§  Large veins have valves that keep blood moving toward the heart.

§  Many veins are located near and between skeletal muscles. Why?

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Diseases of the Circulatory System

Atherosclerosis http://www.youtube.com/watch?

v=qkeHUsJSViE

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