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 are the three main types of blood vessels?
Veins, arteries and capillaries
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?
The heart pumps the blood out at high pressure so the artery walls are strong and elastic with elastic fibres and thick layers of smooth muscle
The walls are thick compared to the lumen
How are capillaries adapted?
Arteries branch into capillaries which supply food and oxygen and take away waste products like CO2
They have very thin (one cell thick with a nucleus) walls - this increase the rates of diffusion by decreasing the distance over which it happens
They have permeable walls so sunstances can diffuse in and out
They carry the blood really close to every cell in the body to exchange substances with them
How are veins adapted?
The blood is at a lower pressure in the veins so the walls don’t need to be as thick as artery walls
They have a big lumen to help the blood flow despite the lower pressure
They have walves to help keep the blood flowing in the right direction
What do arteries do?
Carry blood AWAY from the heart
What do veins do?
Carry blood TO the heart
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
Why does your heart rate increase after excercise?
When you exercise, your muscles need more energy, so you respire more
You need to get more oxygen into the cells and remove more carbon dioxide
For this to happen, the blood has to flow faster, so your heart rate increases
What 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 do the heart valves do?
Controls blood flow
What does the pulmonary artery do?
Takes deoxygenated blood to the lungs