transport in animals Flashcards
why is there a need for a transport system in animals
- size - o2 and nutrients wont reach cells deeper down as its used by outer layer of cells, diffusion distance too great
- SA:V - have a small SA:V ratio, require a transport system to transport o2 and nutrients
- level of activity - aerobic resp. requires o2, cells need good supply of o2 and nutrients for energy to move etc
what is an open circulatory system
blood flows over all the tissues, not contained in arteries/veins/capillaries
blood doesnt transport respiratory gases
insects have an open circulatory system
what is a closed circulatory system
blood flows through system of tubes (arteries etc)
exchange respiratory substances with tissues
fish and mammals have a closed circulatory system
what is a single circulatory system
a full circuit of the organism requires only one visit through heart
insects and fish have a single circulatory system
what is a double circulatory system
full circuit of the organism requires two visits through the heart
why is a double circulatory system more efficient than a single one
maintains a higher pressure,
heart gives blood an extra push betw. lungs and rest of body,
blood travels faster and delivered to tissues quicker
why do mammals have a double circulatory system but fish only have one
fish arent as active and dont maintain their body temperature
why dont all mammals have an open circulatory system
blood will remain at a low pressure and flow rate is slow
not sufficient to supply the muscles of active mammals with o2 and glucose
the cardiac cycle
- atrial systole
muscles of atrium wall contract, decreasing the volume,
pressure increases and is greater than in the ventricle
this forces the atrioventricular valve open
blood flows high to low pressure (atrium–>ventricle)
muscle of atrium wall begins to relax - ventricular systole
muscles of ventricular wall contract, decreasing volume
pressure increases, and is greater than atrium, forcing AV valve shut
muscles continue contracting increasing pressure
pressure greater than in artery forcing semilunar valve open
blood flows to artery, stretching its elastic fibres - ventricular diastole
elastic fibres recoil, decreasing volume and increasing pressure, forcing SL valve shut
blood moves out of artery, high to low hydrostatic pressure
during ventricular diastole, atria refill with blood
why is pressure in the left ventricle more than the atrium
ventricle has to pump blood further, all around the body not just to the lungs
how is tissue fluid formed
blood enters capillaries at a high blood pressure
forces small molecules such as water, glucose, ions through walls of endothelial cells
most water returns to blood through osmosis by lymph vessels- ensures tissues arent filled w too much fluid
coordination of the cardiac cycle
- SAN initiates wave of depolarisation,
- spreads down both atrium walls stimultaneously
- atria contract from top to bottom
- wave stops at non conducting collagen tissue at base of atria
- wave is delayed at the AVN, giving time for the atria to completely empty before ventricles contract
- wave is transferred to bundle of His then up the Purkyne fibres at base of ventricle
- wave travels up both ventricle walls stimultaneously
- ventricles contract bottom to top
- cells repolarise
ECG
PQRST:
P spike - depolarisation of atria
delay betw P + Q - delay at AVN
QRS complex - depolarisation of ventricle wall
T spike - repolarisation of ventricle wall
types of ECGs
tachycardia - too fast
brachycardia - too slow
ectopic - one irregularity
fibrillation - lots of irregularities
fetal haemoglobin
fetal haemoglobin has a higher affinity for o2
at the same partial pressure, fetal hb will be more saturated w o2 than adult hb
