Circulatory System

Blood is the correct answer. The circulatory system's primary function is transporting blood throughout the body, which carries oxygen, nutrients, hormones, and waste products. Water, oil, and minerals are not the main transport medium - they are substances dissolved or carried IN the blood.

Blood vessels are the correct answer. The circulatory system comprises three main components: the heart (pump), blood (transport medium), and blood vessels (the network of tubes). Lungs, bones, and ribcage are parts of other body systems (respiratory, skeletal).

Four is correct. The human heart has four chambers: right atrium, right ventricle, left atrium, and left ventricle. This is a fundamental anatomical fact. Fish hearts have two chambers, amphibian hearts have three, but mammalian hearts have four.

WBC (White Blood Cells) is correct because white blood cells are the primary component of the immune system that fights infections and diseases. RBCs carry oxygen, platelets help with blood clotting, and plasma is the liquid medium that carries the cells.

Arteries is correct. Arteries carry oxygenated blood away from the heart to body tissues (except pulmonary arteries which carry deoxygenated blood to lungs). Veins bring blood back to the heart. Capillaries are tiny vessels for exchange. Ventricles are heart chambers.

RBC (Red Blood Cells) is correct because red blood cells contain hemoglobin, which binds to oxygen molecules in the lungs and releases them to tissues. WBCs fight disease, platelets help clotting, and plasma is the liquid medium that carries the cells.

Plasma is correct because plasma is the liquid portion of blood (about 55% of blood volume) that carries blood cells, nutrients, hormones, and waste products. RBCs and WBCs are cells, not liquid. Water alone is not the transport medium in blood.

Right atrium is correct because the two upper chambers of the heart are the left atrium and right atrium. The lower chambers are ventricles. Aorta is the main artery, not a chamber. This is basic heart anatomy.

Veins carry blood toward the heart. After body cells use oxygen, blood becomes deoxygenated (impure) and returns through veins to the right side of the heart, which then pumps it to the lungs via pulmonary arteries. The key distinction is that veins carry blood back to the heart regardless of oxygenation level.

The heart has four chambers: two upper chambers (atria) and two lower chambers (ventricles). The question specifically asks for the TWO LOWER CHAMBERS, which are the left ventricle and right ventricle. The atria receive blood; the ventricles pump blood out.

The three types of blood vessels in the circulatory system are arteries (carry blood away from heart), veins (carry blood toward heart), and capillaries (tiny vessels where gas/nutrient exchange occurs between blood and tissues). Arteries and veins are transport vessels; capillaries are exchange vessels.

Heart valves are one-way gates that prevent backflow of blood. The atrioventricular valves (tricuspid on right, mitral on left) prevent backflow from ventricles to atria. Semilunar valves (pulmonary and aortic) prevent backflow from arteries back into ventricles. This ensures blood flows only in the forward direction.

The right side of the heart receives deoxygenated blood from the body through the superior and inferior vena cava. This blood has delivered its oxygen to body tissues and picks up carbon dioxide as waste. The right ventricle then pumps this deoxygenated blood to the lungs via pulmonary arteries for reoxygenation.

Blood vessels form the complete circulatory pathway through which blood travels. Red blood cells, platelets, and plasma are components carried WITHIN the blood, but the vessels themselves (arteries, veins, capillaries) are the infrastructure that allows circulation to all body tissues.

Lymphocytes (specifically B-lymphocytes) are white blood cells responsible for producing antibodies as part of the adaptive immune response. When they detect foreign antigens, they differentiate into plasma cells that mass-produce specific antibodies to neutralize pathogens. Leucocytes is the general term for all white blood cells; phagocytes engulf pathogens; erythrocytes are red blood cells.

Platelets (thrombocytes) are cell fragments essential for blood clotting (coagulation). When a blood vessel is damaged, platelets adhere to the site, release chemical signals to recruit more platelets, and provide surface for clotting factors to form fibrin mesh that traps blood cells to stop bleeding. RBCs carry oxygen; WBCs fight infection; plasma is the liquid medium.

Blocked blood circulation deprives tissues of oxygen and nutrients. When coronary arteries are blocked, heart muscle cells die from oxygen deprivation, causing a myocardial infarction (heart attack). Fever and headache have different causes; fractures are bone injuries, not circulation problems. This is why timely restoration of blood flow (e.g., angioplasty) is critical.

Hemoglobin is the red pigment found in red blood cells that gives blood its characteristic red color. It contains iron and binds to oxygen, allowing red blood cells to transport oxygen throughout the body. Plasma is the liquid portion of blood, platelets help with clotting, and carbon dioxide is a waste product transported by blood.

Clotting (or coagulation) is the process where blood changes from liquid to solid form to stop bleeding. This process involves platelets and clotting proteins that work together to form a clot at the site of injury. Supporting, collecting, and resisting are not terms used to describe blood solidification.

Phagocytes and lymphocytes are both types of white blood cells (leukocytes) that play crucial roles in the immune system. Phagocytes engulf and digest pathogens, while lymphocytes (including B and T cells) target specific threats. Red blood cells carry oxygen, platelets aid clotting, and plasma is the liquid portion.

Leucocytes (or leukocytes) is the scientific term for white blood cells, which are responsible for fighting infections in the body. While phagocytes are a specific type of white blood cell that engulf pathogens, leucocytes is the broader category. Erythrocytes are red blood cells, melanocytes produce skin pigment.

Blood constitutes approximately 8% of total body weight in an average adult. This percentage can vary slightly based on factors like age, sex, and overall health. The other options (9%, 10%, 12%) are not accurate representations of blood's proportion of body weight.