Circulation Flashcards
How is the structure of an artery related to its function?
thick muscle wall to transport high pressure, oxygenated blood around around body
What are the adaptations of red blood cells?
no nucleus: more space for haemoglobin
haemoglobin: associates with oxygen to transport around body
Why is a mass transport system needed?
take materials from exchange surfaces to cells when transport is over large distances
What are the key features of a mass transport system?
transport medium e.g. blood
bulk movement over large distances
closed system of tubular vessels, forming a branching network
mechanism for moving transport medium through vessels
mechanism to ensure mass flow is unidirectional
mechanisms for controlling flow to suit changing needs of organism
What is the difference between systemic and pulmonary?
systemic-> oxygenated to body/deoxygenated to heart
pulmonary-> to the lungs
What are the blood vessels going in and out of the liver?
hepatic artery
hepatic portal vein
hepatic vein
What are the blood vessels going in and out of the kidney?
renal artery
renal vein
What makes an organism more likely to have a circulatory pump?
large size: surface area to volume ratio
material need to be transported over large distances
activity of organism -> high activity will require more demand for materials such as oxygen for respiration and metabolic processes
What is the main advantage of double circulation?
more efficient for transporting oxygen and nutrients to the body as greater volume of blood can be pumped out of heart
Why is an arteriole described as an organ?
made of more than 1 tissue
How do arterioles reduce blood flow to capillaries?
muscle fibres contract, reducing size of lumen so less blood can flow through
What is the advantage for slow blood flow in capillaries?
Allows for proper gaseous exchange / gives enough time for diffusion to take place
How does the structure of the capillary adapted to the exchange of substances between blood and the surrounding tissue?
1 cell thick providing short diffusion distance
small diameter gives larger surface area to volume ratio
permeable wall to allow substances to diffuse across
fenestrations allow large molecules through
narrow lumen reduces flow rate giving more time for diffusion
rbc in contact with walls, short diffusion distance
What is transported in plasma?
plasma proteins
nutrients
CO2
Hormones
Urea
Heat energy
What are the specialisations of erythrocytes?
biconcave shape -> larger SA
No nucleus -> more space
haemoglobin -> transport O2
What are albumins?
plasma protein which regulates osmotic pressure of blood
what are globulins?
plasma protein which participate in the immune system and act as transport proteins
what are fibrinogens?
plasma protein involved in the clotting process
How is tissue fluid formed?
in capillaries, hydrostatic pressure is higher at arteriole end
pushes fluid out of capillary
it is opposed by the water potential of blood, which is lower than tissue fluid and hydrostatic pressure of tissue fluid
fluid forced out by ultrafiltration
How is water reabsorbed into capillary?
formation of tissue fluid reduces water potential of blood as plasma proteins remain in capillary as cannot cross basement membrane
creates water potential gradient
water moves in via osmosis
fluid moves into capillary, some tissue fluid drains into lymphatic system to be returned to blood
What happens to the 10% tissue fluid?
drains into lymphatic system where it forms lymph which is a colourless/pale yellow fluid similar to tissue fluid, but contains more lipids
lymphatic system drains into the capillary system near the vena cava via the thoracic duct
What are lymph nodes?
sac-like organs that trap pathogens and foreign substances, which contain large numbers of white blood cells
High blood pressure leads to an accumulation of tissue fluid. Explain why
less tissue fluid reabsorbed
high hydrostatic pressure
increases outward pressure at arterial end / reduces inward pressure at venule end
Why is water potential of blood plasma lower at venule end?
water moves out of capillaries at arteriole end
plasma proteins too large to move out
so water potential decreases due to high concentration of blood proteins
