Lab Topic 28
Investigating Circulatory Systems

General
What are the parts that any circulatory system must include?
What are the functions of circulatory systems in vertebrate animals? How is circulation important in gas exchange, nutrient uptake, waste disposal, and body defense?
What is the functional importance of capillaries, and what structural features are important to that function?
What regulates blood flow in a capillary bed?

Invertebrate Circulatory System
  • Do crayfish, like that illustrated here, have an open or closed circulatory system? What other animals have a circulatory system of this type?
  • What is the circulatory fluid in this animal called? Why isn't it just called blood?
  • Where would you find the heart in this animal?
  • Where do you find an ostium (Latin for door; plural is ostia) in the crayfish and what is its functional importance?
  • How does hemolymph return to the crayfish heart?
  • Diagram how a crayfish circulatory system works.
  • Do crayfish have arteries? What is their function? Do crayfish have veins?

Mammalian Circulatory System
The Heart and Its Vessels
  • Name the 4 chambers of the heart and describe what they do.
  • Where are the aorta and vena cavae, and what is the function ofe each?
  • What is the main difference between the atrial and ventricular chambers?
  • What is ths function of the carotid arteries?
  • Is this a ventral or dorsal view of the heart? How can you tell?
  • Which chamber of the heart is the strongest and why? Where is it in this picture
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  • Point out the right and left atria, and the right and left ventricles.
  • Point out a coronary artery. Is the blood in this vessel oxygen rich or oxygen poor? Why does heart muscle need a blood supply, when all the blood in the body passes through the heart every minute or so?
  • Where does the blood flow immediately after leaving the pulmonary artery? Is this blood oxygen rich or oxygen poor?
  • Where would you find the pericardial membrane?
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  • Name and point out the vessel that brings blood to the right atrium
  • Name the four valves that control blood flow in the heart, and for each, list the chamber or blood vessel on the upstream side and the downstream side.
  • When this chamber contracts, will this valve close or open?
  • In this model, where is the aorta? The pulmonary artery? What is the function of each?

Vessels Cranial to the Heart
  • The internal and external jugular veins connect which body regions to the heart?
  • Do the jugular veins carry blood to or from the heart?
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  • Identify these blood vessels and indicate where each carry blood.
  • Locate the jugular vein and carotid artery.
  • What is the function of each?
  • Which has the higher blood pressure? Why?

Vessels Caudal to the Heart
This image has the liver, stomach, pancreas, and intestine removed.
  • What remaining organs can you identify?
  • Point out a spinal nerve. An intercostal (= between the ribs) artery
  • Name and identify the large vein and large artery that run caudal to the heart.
  • What is the largest vein in a fetal pig and why?
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  • What are the paired organs in this illustration? What is their function?
  • What are the blood vessels that bring blood to and away from these organs? Why do such small organs have such a large blood supply?
  • What are the whitish tubes running posterior from the middle of each kidney? What is their function? Where do they go after leaving the kidneys?
  • Where would you look for the adrenal glands in this picture?
/ This illustration shows a fetal pig's left hind leg with the femoral artery exposed.
  • What would be the name of the corresponding artery that supplies blood to the foreleg of this pig?

Internal Heart Structure
 / /
Longitudinal section of heart
  • Can you identify the chambers of the left and right ventricle? Left and right atrium?
  • Point out the tricuspid valve. The bicuspid valve.
  • Where does the blood leave the left ventrical?
  • Where are the chordae tendinae, and what is their function
/ Cross section of the heart
  • Point out the left ventricle and the right ventricle. How can you tell the two apart in this section?
  • Why does the left ventricle have thicker walls than the right ventricle? Is there any difference in the amount of blood that each pumps?
  • What is the ventricular muscle doing during systole? During diastole?
/ Heart model
  • What are the structures near the top of each ventricle that are colored white in this model? What is their function and how do they work?
  • What is the large blue vessel near the top of the heart in th center, and what is its function?
  • What is the smaller blue vessel running down the middle of the heart, and what is its function?
  • Which of the four chambers has the most pumping power? Which has the second most pumping power? What anatomical details support your answer?

Blood vessel histological structure and function
 / /
Cross-sections of artery and vein
  • How do arteries and veins differ in structure and function? Which contain blood under higher pressure? Which have relatively thicker layers of muscle in their walls?
  • Where in these sections is the endothelium? The muscle layers? The blood cells?
  • How many cell layers thick are the walls of a capillary?
  • Can you think of a reason why arteries have heavy muscle and connective tissue layers and veins have thin layers?
  • What prevents blood in veins from flowing backward? Why do veins have valves that prevent backflow, but arteries do not?
  • If blood vessels did not have endothelial cells what would happen?

Artery Wall / Vein Wall

What are the lightly stained cells inside the artery and vein sections? What kind of muscle is in the walls of these vessels?

Blood
Mammalian blood smear
  • What types of cells are visible in this image? Point out an erythrocyte and a leucocyte.
  • How many nuclei do the red blood cells of this species have?
  • Does human blood contain more red blood cells or white blood cells per unit volume?
/ Mammalian blood smear, stained with Wright's stain
  • What are the functions of the white blood cells?
  • What is the function of red blood cells?Why are they red?
  • The most common leukoycytes are ____ which are instrumental in consuming cell debris and bacteria and ______which are important to the immune response.
  • Platelets represent another cellular element, or at least a cell fragment in blood. In this slide platelets are visible as small purple dots. Locate one. What is the function of platelets?

General and Comparative Questions

  • As animals get bigger and more complex, why is a circulatory system needed to maintain homeostasis?
  • What functions does a circulatory system perform?
  • Describe the differences between open and closed circulatory systems.
  • Compare the heart pumping systems of arthropods, annelids, and vertebrates.
  • Trace a red blood cell from the time it leaves the lungs to the time it arrives in the carotid artery.
  • Trace a red blood cell from the time it leaves the liver to the time it enters the capillaries of the lungs.
  • Trace a molecule of oxygen from the time it enters the nostril to the time it leaves the body as oxygen in a water molecule voided in the urine.
  • What is the definition of artery and vein? In which is blood normally best oxygenated? Are there any arteries that routinely carry poorly oxygenated blood? Any veins that routinely carry well-oxygenated blood?
  • Where is the spleen and what does it do? Why is it dangerous to have a ruptured spleen?
  • If you played a contact sport, why would the spleen be an easy organ to damage?

Credits
Images and layout provided by Warren D. Dolphin and Linda M. Westgate