The Circulatory System

Question 1

Role of the circulatory system

Answer 1

• transports substances around the body
• oxygen and carbon dioxide between lungs and body tissues
• nutrients from intestines
• wastes to kidneys
• hormones from endocrine glands
• white blood cells and antibodies for the immune system

Question 2

Types of systems

Answer 2

• closed circulatory systems confine our red blood cells to blood vessels
• plasma and white blood cells are allowed to directly enter tissues
• open circulatory systems allow blood to meander throughout the body cavity, crustaceans use systems like this

Question 3

The heart

Answer 3

• some organisms have simple hearts that are simply twitchy contractile blood vessels
• real hearts have atria to collect blood from veins and ventricles that pump blood back out to arteries
• valves prevent blood from flowing backwards through the heart

Question 4

Types of division

Answer 4

• pulmonary division = the right side of the heart pumps deoxygenated blood to and from the lungs via pulmonary arteries and veins
• systemic division = the left side of the heart pumps oxygenated blood to the rest of the body via the aorta and collects deoxygenated blood from the lower and upper body via the inferior and superior vena cava

Question 5

Blood vessels

Answer 5

• arteries = carry high pressure blood away from the heart
• capillaries = the smallest blood vessel, red blood cells must pass single file, where materials are exchanged between blood and tissues
• veins = carry low pressure blood back to the heart, between skeletal muscles so body movement can squeeze blood back from the extremities, valves prevent blood from flowing backwards

Question 6

Blood

Answer 6

• plasma = about 60%, primarily water and dissolved molecules
• blood cells = about 40%, depending on your fitness, 3 types

Question 7

Red blood cells

Answer 7

• erythrocytes
• contains hemoglobin to carry oxygen and proteins
• a fixed, biconcave shape maximizes surface area and ensures they don’t get stuck in capillaries

Question 8

White blood cells

Answer 8

• leukocytes
• many different types form antibodies, recognize and engulf pathogens
• these are amoeboid and can squeeze out of capillaries and into infected tissues

Question 9

Platelets

Answer 9

• these are cell fragments and gather at an injury

* along with clotting factor proteins, they form clots to stops bleeding from damaged blood vessels