General Flashcards
Features of an artery
Large amount of elastic tissue to compensate for a large amount of high-pressure blood entering the artery and can control the pressure of blood
Large amount of thin muscle in the arterioles, meaning that when the walls contract, the lumen will decrease in size, allowing for blood to travel from one area to another
Thick walls so the arteries can resist the pressure of the blood
Very smooth endothelium, allows blood to flow smoothly through the artery
No valves inside the artery, only before the artery begins
Small lumen diameter
Expand to reduce pressure
Recoil to increase pressure
Features of a capillary
No elastic tissue
No smooth muscle
One cell thick walls which enhances gas exchange, cells are sideways to further make the walls thins
The wall of a capillary is made of endothelium only, with no other
layers of tissue
No valves
Very small lumen, only being 8μm in diameter
Why do single-celled organisms not need a circulatory system?
Single-celled organism do not need to circulatory systems as they rely solely on ribosomes for respiration purposes, there is not a need for a full system in the single-celled organism as the body of the cell allows for gas exchange. They are small enough that they do not need blood and they can diffuse waste products (co2) and nutrients. Small volume, large surface area
Why do multicellular organisms need a circulatory system?
Animals need circulatory systems so they can control the flow of nutrients and oxygenated/deoxygenated blood through their body. It allows for the nutrients to be distributed through the body’s tissues via capillaries and for the exchange of oxygen in the blood. Too large volume-surface area ratio to rely solely on diffusion, cannot remove co2 and other waste effectively
Function of arteries
To pump blood out of the heart either to be oxygenated (pulmonary artery) or to distribute oxygenated blood through the body (aorta). Moves high-pressure blood and regulates blood pressure because they have thick walls
Function of capillaries
They are the site of nutrient and oxygen transfer
Function of veins
To allow blood to flow back into the heart such as if the blood is oxygenated (pulmonary vein) or to return deoxygenated to the heart for re-oxygenation (vena cava). Moves low-pressure blood.
What aspect of an organism’s lifestyle dictates whether or not the organism needs a circulatory system?
The level of activity affects whether or not an organism needs a pump and a system / the size of the organism
