Circulatory System

SBI 3U

Ms. Raper

Open circulatory system• Found in many

insects• Blood returns to the

heart via the movement of the animal’s body.

• inefficient

http://fajerpc.magnet.fsu.edu/Education/2010/2010_INDEX.HTM

Closed Circulatory System

• Found in some invertebrates such as worms and in fish, reptiles, birds and mammals

• Blood never leaves a system of tubes

• Heart pumps blood around the body

William Harvey 1568 -1657

• Was a physician trained in Italy.

• Was the first to accurately describe the action of the heart pumping blood around the body.

• He confirmed the presence of valves in the veins to prevent the backflow of blood.

• He confirmed his theories by carrying out dissections. http://www.bbc.co.uk/history/historic_figures/harvey_william.shtml

Blood Vessels• Arteries – carry blood AWAY from the heart.

• Veins – carry blood back to the heart – blood returns VIA the veins.

• Capillaries – CONNECT arteries and veins, it is here that substances are loaded and unloaded into the

blood by diffusion.

http://www.owensboro.kctcs.edu/gcaplan/anat2/notes/Notes5%20Circulatory%20Anatomy.htm

Arteries

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookcircSYS.html

•Thick elastic muscular walls

•Small lumen

•Carry oxygenated blood (except pulmonary artery)

•Carry blood away from the heart.

Veins

• Have thin walls

•Large lumen

•Carry deoxygenated blood (except pulmonary vein)

•Have valves to prevent backflow of blood

•Carry blood back to the heart

Circulatory System

Blood vessels

Arteries

• Have a smaller lumen than veins

• Have thick Muscular walls.• Carry oxygenated blood

(except the Pulmonary artery)• Have a pulse• Carry blood away from the

heart• Have blood under high

pressure• Blood is BRIGHT red• A cut artery spurts with the

heart beat.• Main artery is the AORTA

Cross section through an artery.

Capillaries

• Connect arteries and veins.

• Are found in organs.• Are where substances

are dropped off or picked up from the cells

• Are only one cell thick.• Red Blood Cells must

travel through in single file.

• Low pressure• Cut capillaries ooze Cross section of a capillary

• Veins have thinner muscular walls than arteries,

• Have a large lumen,• Have valves to prevent

backflow of blood• Carry blood back to the heart• Carry deoxygenated blood

(except the pulmonary vein)• Have blood that is DARK red.• Low pressure• A cut Vein will gushes.• Main vein is the VENA CAVA

Blood Vessels.

http://iws.ccccd.edu/mweis/Images/Histology/2402%20histology/Circulatory%20Histo/labeled%20circ%20histo/circ_vessels_av_compare_heading.png

Exchange in Capillaries

Coronary Arteries

http://www.patient.co.uk/showdoc/Pilsinl/112.gif

Peripheral Arteries

http://www.patient.co.uk/showdoc/Pilsinl/101.gif

3 parts to the Circulatory System

• Cardiac - blood supply to and through the heart.

• Pulmonary – blood flow through the lungs.• Systemic – blood flow through the body other

than the lungs and heart.• Because blood flows through the heart twice for

every complete circuit, it is referred to as a DOUBLE circulation.