Blood and Circulation Flashcards
Why do single celled organisms not need circulatory systems?
They can obtain oxygen through the surface membrane of the cell
What do valves control?
The flow of blood to the heart
What does blood clotting prevent?
The entering of pathogens and the prevention of excess blood loss
Why do people need a transport system to carry sugar and oxygen to cells?
Humans have a very low surface area:volume area
What is the process of double circulation?
The heart pumps blood to the lungs, getting back oxygenated blood which is sent to the heart to pump around the body
What do valves do in veins?
Stop blood flowing in the wrong direction
How are arteries adapted?
They have thick muscular walls to smooth out the pulses blood flow from the heart. Their walls must be able to stretch and they must be able to stretch and recoil.
How are capillaries adapted?
They have very thin walls so that diffusion can occur more quickly. They bring the blood close to every cell in the organ. They must be small enough to fit between cells.
How are veins adapted?
Large to carry blood to the heart Pressure is lower than in arteries, blood must be able to flow easily.
What do arteries do?
Usually carry blood AWAY from the heart (except pulmonary artery)
What do veins do?
Carry deoxygenated blood BACK to the heart (except pulmonary vein)
Where does blood enter?
The atria of the heart
What happens when the ventricles contract?
Blood leaves the heart and travels to the lungs and around the rest of the body
How many heartbeats a minute (approx)
70
What does your heartbeat increase after excercise
More oxygen is needed in the body
Wat (lady) changes as the heart empties and fills?
The blood pressure
What does the aorta do?
Carries oxygenated blood around the body
What does the pulmonary vein do?
Brings oxygenated blood from the lungs
What does the heart valves do?
Controls blood flow