Circulatory system Flashcards
Name three common features of a mammalian circulatory system
-suitable medium for transport, water based to allow substances to dissolve
-means of moving the medium and maintaining pressure throughout the body, such as the heart
-means of controlling flow so it remains directional, such as the valves
draw a diagram of the human heart
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relate the structures of the chambers to their function
atria: thin walled and elastic, so they can stretch when filled with blood
-ventricles, thick muscular walls pump blood under high pressure. The left ventricle is thicker than the right because it has to pump blood all the way around the body
relate the structure of the vessels to their function
-arteries have thick walls to handle high pressure without tearing, and are muscular and elastic to control blood flow.
-veins have thin walls due to lower pressure, therefore requiring valves to ensure blood doesn’t flow backwards. Have less muscular and thick elastic tissue as they don’t have to control blood flow
why are two pumps (left and right) needed instead of one?
-to maintain blood pressure around the whole body. When blood passes through narrow capillaries of the lungs, the pressure drops sharply and therefore would not be flowing strongly enough to continue around the whole body. Therefore it is returned to the heart to increase the pressure.
describe what happens during cardiac diastole
The heart is relaxed. Blood enters the atria, increasing the pressure and pushing open the atrioventricular valves. This allows blood to flow into the ventricles. Pressure in the heart is lower than in the arteries, so semilunar valves remain closed
describe what happens during atrial systole
-the atria contract pushing any remaining blood into the ventricles
describe what happens during ventricular systole
the ventricles contract. The pressure increases, closing the atrioventricular valves to prevent backflow, and opening the semilunar valves. Blood flows into the arteries
names the nodes involved in heart contraction and where they are situated
sinoatrial node (SAN) : wall of right atrium
atrioventricular node (AVN) : in-between the two atria
what does myogenic mean?
the heart’s contraction initiated from within the muscle itself, rather than by nerve impulses
how is the structure of the capillaries suited to their function?
- walls are only one cell thick; short diffusion pathway
-very narrow, so can permeate tissues and red blood cells can lie flat against the wall, effectively delivery oxygen to tissues
-numerous and highly branched, providing a large surface area
what is tissue fluid? (PLANTS)
a watery substance containing glucose, amino acids, oxygen, and other nutrients. It supplies these to the cells, while also removing waste material
how is tissue fluid formed? (PLANTS)
-as blood is pumped through increasingly small vessels, this creates hydrostatic pressure which forces fluid out of the capillaries. It bathes the cells, and then returns to the capillaries when the hydrostatic pressure is low enoug
