10. Mass Transport In Animals Flashcards
Why is it important oxygenated and deoxygenated blood doest mix?
Less oxygen will be delivered to cells of respiring tissue so less oxygen available for aerobic respiration so tissue/organ does grow/develop properly so may stop working and die.
What blood vessel delivers blood to cardiac muscle of heart?
Coronary artery- if not enough glucose/oxygen delivered to cardiac muscle via coronary artery, could cause heart attack.
What is the cardiac cycle? (Remember pressure volume and valves.)
ATRIAL SYSTOLE: atrial walls contract, vol atrial decreases, pressure atria increases, force remaining blood through AV valve into ventricles, blood flow into ventricles
VENTRICULAR SYSTOLE: ventricle wall contract from base of heart up, vol ventricle decreases, increases pressure above that of atria, pressure increases in ventricle above arteries, semi lunar valves open, blood flow into arteries and put heart via aorta/pulmonary artery.
DIASTOLE: ventricles relax and recoil, semi lunar valves close, AV valve open and whole heart fills with blood, pressure increases ventricle decreases, blood flow into atria.
What change in pressures cause AV and semi lunar valves to open and close?
- pressure in atria higher than ventricles, AV open
- pressure in ventricles higher than atria, AV close
- pressure ventricles higher than aorta, semi lunar open
- pressure aorta higher than ventricles, semi lunar close
Whats the structure of arteries?
- thick muscular wall (withstand high pressure)
- contains elastic tissue ( allow stretching/recoil to smooth out blood flow maintain blood pressure)
- smooth endothelium layer next to lumen (reduce friction)
- semi lunar valves open (from aorta into ventricles)
- narrow lumen (maintain high blood pressure)
Whats the structure of veins?
- thinner walls
- valves (prevent back flow of blood)
- larger lumen (reduce resistance to blood flow)
- smaller amount of elastic fibres ( as pressure is lower)
- contain smooth endothelium layer next to lumen ( reduce friction)
What are arterioles? Why do aorta have a higher blood pressure than smaller arterioles?
Smaller vessels than arteries and connect artery to capillaries as diameter of lumen is smaller than arteries, more friction between blood and wall, reducing blood pressure. They can reduce blood
flow to capillaries by contracting muscle layer which narrows lumen
Aorta closer to heart where pressure is very high, has elastic tissue which stretch and recoil when heart beats causing greater blood pressure.
What is the structure of capillaries?
- 1 cell thick ( increase rate of diffusion as short diffusion pathway)
- branched (increases SA for diffusion)
- narrow lumen (RBC in contact with wall , reduces diffusion pathway)
- pores between smooth endothelium ( allow exchange of substances.)
How does tissue fluid form?
At the arterial end, hydrostatic pressure high due to the heart contracting. Higher than opposing water potential gradient so fluid (dissolved substances) forced out the capillary into tissue. Plasma proteins remain in the capillary as they are to large. Increases in proteins in capillary lowers water potential gradient. Hydrostatic pressure lowers as move to venous end as distance from heart increases and loss of water/friction. Water move back into capillary at venous end due to hydrostatic pressure being lower than opposing water potential gradient so move by osmosis. Excess fluid reabsorbed by Lymphatic system.
Why does high blood pressure lead to an accumulation of tissue fluid?
High blood pressure lead to high hydrostatic pressure, so increases outward pressure from arteriole end and reduces inward pressure at venous end so more fluid formed and less reabsorbed. Lymphatic system not able to drain excess fast enough.
Why does starving lead to tissue swelling?
Reduction in plasma proteins so water potential isn’t as low as normal, reducing the water potential gradient between plasma and tissue. so less fluid is reabsorbed at venous end so more stays in the tissue.
What is a correlation in data?
When theres an increase in one variable that causes an increase in another. Positive correlation.
Strong correlation doesn’t mean that theres a causal link (something which causes it).
In answer say theres a +/- correclation however this doesnt show a causal relationship because (state factor: e.g. lack data, gaps in data, not all points follow trend, no sig difference.)
How does the heart control/coordinate the regular contraction of atria and ventricles (control of cardiac cycle)?
SA Node sends a cardiac impulse causing atriall to contract as it spreads through muscles cells of wall of atria.
Non conducting tissue prevents immediate contraction of ventricles.
AV Node delays impulse whilst blood leaves atria.
AVN sends impulse down Bundle of His. Spreads up the walls of 2 ventricles by Purkinje Fibres causing the ventricles to contract from the base up and pushing blood out heart via pulmonary artery and aorta.
