chapter 12 Flashcards
Two Types of Circulatory Systems
- Open System:
Blood flows freely within the body cavity.
Makes direct contact with organs and tissues.
Example: Insects, crustaceans. - Closed System:
Blood is physically contained within vessels.
Blood follows a continuous fixed path.
Example: Earthworms, birds, humans.
Structure of the Heart
- The heart consists of two double pumps separated by the septum.
- The right pump receives deoxygenated blood to the lungs (pulmonary circuit).
- The left pump receives oxygenated blood to the cells of the body (systemic circuit).
-Blood flow through the heart is called the cardiac circuit.
Valves in the Heart
Atrioventricular Valves:
Tricuspid valve (right atrium to right ventricle).
Bicuspid valve (left atrium to left ventricle).
Semilunar Valves:
Aortic and pulmonary valves.
Valves control the flow of blood through the heart.
Heart murmur may occur if valves don’t close properly.
The Four Chambers of the Heart
The heart has four chambers: two atria and two ventricles.
Blood Vessels
Arteries:
Carry blood away from the heart at high pressure.
Made up of three strong layers.
Veins:
Carry blood towards the heart at lower pressure.
Thinner than arteries.
Have one-way valves to keep blood moving forward.
Capillaries:
Narrowest blood vessels.
Allow for slow blood flow and low pressure.
Facilitate gas exchange through diffusion.
Recap: Overall Flow
Arteries → Arterioles → Capillaries → Venules → Veins.
The Overall Path of Blood (in a closed system)
Arteries → Arterioles → Capillaries → Venules → Veins → Heart.
Components of Blood
Blood consists of plasma (55%) and cells (45%: RBCs, WBCs, and platelets).
Red Blood Cells (Erythrocytes)
-Made in bone marrow, contain hemoglobin.
-Biconcave shape for maximum O2 transport.
-Hemoglobin gives blood its red color.
Blood Doping
-Athletes may undergo blood doping to increase RBC count for enhanced performance.
Anemia
-Decreased hemoglobin in the blood.
-Can be caused by genetic disorders or lack of dietary iron.
White Blood Cells (Leukocytes)
-Made in bone marrow.
-Defend against foreign invaders.
-Some use phagocytosis to engulf pathogens
Platelets (Thrombocytes)
-Cell fragments that initiate blood clotting.
-Form a plug to prevent further bleeding.
Functions of Blood: Temperature Regulation
-Circulatory system regulates temperature by changing blood flow near the skin.
- Vasodilation releases heat, vasoconstriction conserves heat.
Cardiovascular Disease Risk Factors:
Smoking
Obesity or poor diet
Insufficient exercise
Genetics