MBLEx Study Guide: Circulatory System
Latest Update with complete solution
Primary functions of the circulatory system - Answer--Picking up oxygen from the lungs
and delivering it to the cells of the body.
-Removing carbon dioxide that is produced by cellular metabolism, and delivering it to
the lungs to be removed.
-Transporting nutrients that are absorbed through the gastrointestinal system (GI) to the
body cells to produce energy.
-Transporting blood through the filtering organs to remove or recycle waste products.
These filtering organs are the kidneys, liver, and spleen.
-Circulating hormones that act like messengers to communicate with other organs and
tissues.
-Transport other substances like antibodies, electrolytes and platelets.
-Transfer heat from the core to help warm the extremities when cold, and dissipate heat
when hot.
pulmonary circulation - Answer-Blood circulates to and from the lungs in a process
called pulmonary circulation. The blood is pumped out through the right ventricle to the
lungs, and returned to the left atrium of the heart. This process works with the
respiratory system to get rid of carbon dioxide (CO2) and pick up oxygen (O2) at the
alveoli.
Systemic circulation - Answer-covers the rest of the body, from the brain to the toes. In
systemic circulation, CO2 and waste products are picked up from the cells of the bodies
and later removed or recycled. The transfer of these substances occurs at the
capillaries.
Arteries - Answer-Arteries carry blood away from the heart, to the rest of the body. The
blood in arteries is usually oxygenated, except in the arteries that carry blood to the
lungs in pulmonary circulation.
The walls of the arteries are thicker in order to withstand the higher blood pressure in
arteries. Arteries also have a muscular layer, which allows them to adjust the pressure
in the circulatory system. Normal blood pressure is 120/80 mmHg. Large arteries divide
into smaller arterioles, which eventually connect with the capillaries.
Veins - Answer-Veins carry blood towards the heart. They usually carry blood that has
already delivered the oxygen to the body cells, and has picked up carbon dioxide (CO2)
to be taken to the lungs for removal. An exception to this are the pulmonary veins which
carry oxygenated blood back from the lungs to the heart.
The walls of veins are thinner because there is very little pressure. Because of this low
pressure, veins have valves to prevent backflow of blood.
