FACT
Memory trick: the
tRIcuspid valve is
found on theRIght
side of the heart.Figure 8.8: Flow diagram depicting movement of blood from the heart through the circulatory system.
The blue boxes represent deoxygenated blood, the purple boxes represent capillary networks where
gaseous exchange occurs and the red boxes represent stages at which the blood is oxygenated.
Major organs and systemic circulation DUMMY
All the organs of the body are supplied with blood. This is necessary so that the cells can
obtain the necessary nutrients as well as oxygen which is required for cellular respiration.
Each organ has an artery that supplies it with blood from the heart. Metabolic wastes,
including carbon dioxide, need to be removed from cells and returned to the heart. These
move into the capillaries which enter into veins that eventually enters either the superior or
inferior vena cava which then enters the right atrium.
Arteries and veins have been named according to the organ to which they supply blood.
Theliverreceives oxygenated blood from the heart via the hepatic artery. This artery runs
alongside thehepatic portal vein. The hepatic portal vein contains nutrients that have been
absorbed by the digestive system. This nutrient-rich blood must first pass through the liver,
so that the nutrient composition of the blood can be controlled. Blood passes from the liver
to the heart through thehepaticvein. Metabolic waste is circulated in the blood, and if
allowed to accumulate, would eventually reach toxic levels. Thekidneysare supplied with
blood (which contain waste) via therenalarteries. The kidneys filter metabolic waste from
the blood, passing it to urine to be excreted safely. Blood leaves the kidney via the renal
vein.
Thebrainis supplied with blood via thecarotidarteries and the vertebral arteries. The blood
from the brain is drained via thejugularveins. The brain is supplied with 15% of the total
amount of blood pumped by the heart. The heart is also a muscle (myocardium) that requires
blood flow to work. Blood is supplied to the heart via twocoronary arteries, and leaves the
heart via fourcardiac veins.
Chapter 8. Transport systems in animals 229