Adaptations for transport: Animals C3 Flashcards
does insects have an open or closed circulatory system?
open
explain and describe an insect’s circulatory system
fluid is pumped at relatively low pressure from one main long, dorsal tube-shaped heart running the length of the body
fluid called haemolymph bathes the tissue directly, enabling the exchange of substances
when the heart relaxes the haemolymph is sucked slowly back to the heart
there is no respiratory pigment in the insect haemolymph as oxygen diffuses directly to respiring cells through the tracheal system
what does dorsal mean?
at the top/front
what is the blood cavity in the insect called?
haemocoel
what are two examples of organisms with a closed circulatory system?
mammals
fish
explain and describe a mammal/fish’s circulatory system
blood circulates in a fully enclosed system of tubes (blood vessels)
the heart is a muscular pump, pushing blood at high pressure and with a rapid flow rate
organs are not in direct contact with the blood but are bathed in tissue fluid
blood carrier a respiratory pigment which carries oxygen
explain and describe an earthworm’s circulatory system which is closed
has dorsal and ventral vessels running through the length of the body
these are connected by five pairs of pseudohearts
blood contains a respiratory pigment which carries oxygen
what is the difference of blood pressure in a closed vs open circulatory system?
open -
blood under low pressure as it’s not contained within vessels
closed -
blood under high pressure as it is contained within vessels
what is the difference between fluid being in direct contact with organs in an open vs closed circulatory system?
open -
as haemolymph leaves the circulatory system it bathes the organs directly
closed -
as blood is contained within blood vessels, blood never has direct contact with organs
where is blood contained in in open vs closed systems?
open -
blood is pumped from a long dorsal tubular heart into spaces within the body cavity
closed -
blood is always within vessels which include arteries, veins and capillaries
is a respiratory pigment needed in a closed and open system?
open -
oxygen reaches the gas exchange surface via a tracheal system so no respiratory pigment needed to carry oxygen around the body
closed -
oxygen diffuses into the blood and is carried around the body in blood bound to haemoglobin which is the respiratory pigment
where is oxygen transported in a closed and open system?
open -
oxygen is transported directly to tissues
closed -
oxygen is transported from the exchange surface/lungs to the heart and then towards capillaries in body tissues
what is single circulation and which organism has this?
blood passes through the heart once in one complete circulation eg fish
what is double circulation and which organism has this?
blood passes through the heart twice in one complete circulation eg mammals
what are the two circuits in double circulation?
pulmonary circulation
systemic circulation
what is the pulmonary circulation?
to do with lungs
all of the blood vessels involved in transporting blood between the heart and the lungs
what is systemic circulation?
to do with respiring tissues
all of the blood vessels involved in transporting blood between the heart and respiring tissues
how many chambers does a fish heart have?
2
how many chambers does a mammal heart have?
4
give three advantages of a double circulation system over a single circulation system
maintains a high blood pressure in the systemic circulation
allows a lower pressure in the pulmonary circulation
rapid circulation in the systemic circuit
explain the advantage of maintaining a high blood pressure in the systemic circulation
high blood pressure ensures blood reaches all tissues even those very far from the heart
explain the advantage of allowing a lower pressure in the pulmonary circulation
low pressure prevents tissue fluid being pushed out of capillaries into the lungs
explain the advantage of paid circulation in the systemic circuit
ensures oxygen is delivered to respiring cells rapidly
why is it important that oxygenated and deoxygenated blood is kept separate?
maintains a steep concentration gradient for oxygen at the lungs and at respiring tissues
what are the 3 major blood vessels that make up the mammalian circulatory system?
arteries
veins
capillaries
what is the role of arteries?
carries deoxygenated blood away from the heart at high pressure
what is the role of veins?
transports blood to the heart at low pressure
what is the role of capillaries?
smallest vessels that allows exchange of substances with body cells and takes blood as close as possible to all cells
what is the size of an artery?
1-10 mm
what is the size of a vein?
1-15mm
what is the size of a capillary?
<1
describe the endothelium present in the 3 major blood vessels
it is the innermost layer of the vessel, is one cell thick and provides a smooth lining
why is it important that the endothelium is smooth?
to minimise friction to reduce resistance to blood flow
what is the tunica media made of in the arteries?
elastic fibres and smooth muscle
out of veins and arteries, which has the thicker tunica media?
arteries
what is the function of thick smooth muscle in arteries?
allows the vessel to contract and withstand changes in pressure as blood is pumped by the heart
what is the function of thick elastic fibres in arteries?
they are able to recoil to maintain high pressure
what is the tunica externa made of in the blood vessels?
collagen fibres
what is the role of collagen fibres in the blood vessels?
resistant to over-stretching
why do veins have wide-diameter lumens?
so that they can deliver large volumes of blood back to the heart and to reduce resistance to flow
why do veins have thin walls?
since the pressure inside is much lower due to the further distance from the heart
what can the thin muscle layer in the walls do in veins?
they can be compressed easily allowing contracting skeletal muscle to squeeze veins and push blood upwards towards the heart
what do pocket valves do in the veins?
ensure blood flows in one direction towards the heart
how do valves work?
blood above the valves tries to flow back
blood fills the pockets
this forces the valves shut
why do veins above the heart have no valves?
due to gravity
what is role of arterioles?
they can adjust their diameter to vary the blood supply to a capillary bed
what are the walls of capillaries like?
consist of only an endothelium and are one cell thick
some have pores in their walls
capillaries are permeable to water and dissolved substances such as glucose, amino acids, urea, oxygen and carbon dioxide
what do the thin capillary walls allow?
for a more efficient exchange of materials and gases as there is a shorter diffusion pathway and a large cross-sectional area
what is the role of a narrow lumen in capillaries?
restricts blood flow, slowing down the blood to allow more time for the exchange of materials in the tissues and blood cells must distort to pass through the narrow lumen
what is the blood pressure like in capillaries?
falls as the velocity of blood decreases
what does the heart consist largely of?
cardiac muscle
what is special about the cardiac muscle in the heart?
it is a specialised tissue that is capable of rhythmical contraction and relaxation over a long period without fatigue
give the names of the main structures of the heart
there are 16
aorta
superior vena cava
semilunar valves
right atrium
tricuspid (atrioventricular valve)
inferior vena cava
right ventricle
apex
left ventricle
septum
bicuspid (atrioventricular valve)
chordae tendinae (tendinous chords)
papillary muscle
left atrium
pulmonary vein
pulmonary artery
what is the function of tendinous chords in the heart?
when the ventricles contract, the volume of the ventricles decreases and therefore the pressure increases, forcing the atrioventricular valves shut to prevent backflow into the atria
the tendinous chords stop the valves inverting into the atria
what is important to consider when dissecting a heart?
ethical issues
ensure that animals are treated humanely and no animals are killed needlessly
what is the function of the aorta?
it is the largest artery and transports blood from the heart to the body
what is the function of the vena cavae?
two veins that carry deoxygenated blood to the heart from the upper and lower parts of the body
what is the function of the pulmonary arteries?
transport deoxygenated blood from the heart to the lungs where gas exchange takes place
what is the function of the pulmonary veins?
transport oxygenated blood from the lungs back to the heart
what is the function of coronary arteries?
supplies the heart cells with oxygenated blood and glucose for contraction
what is the function of coronary veins?
remove deoxygenated blood from the cardiac muscle
describe the blood flow through the heart and body
10 points to make
oxygenated blood travels from the lungs to the heart in the pulmonary vein
blood leaves the pulmonary vein and enters the left atrium
the left atrium contracts and forces blood into the left ventricle through the bicuspid valve
the ventricle contracts and the bicuspid valve closes, forcing blood upwards into the aorta through the semilunar valves
oxygenated blood leaves the heart via the aorta to travel to the body tissues
deoxygenated blood from the body tissues returns to the heart tissues in the vena cavae
deoxygenated blood moves from the superior and inferior vena cava into the right atrium
the right atrium contracts and blood moves into the right ventricle through the tricuspid valve
the right ventricle contracts closing the tricuspid valve and forcing blood into the pulmonary artery through the semilunar valve
deoxygenated blood travels in the pulmonary artery towards the lungs
give the three stages of the cardiac cycle: the sequence of events in the heartbeat
1 - atrial systole
both the atria contract forcing the tricuspid and bicuspid valves open
blood flows from the atria where there is higher pressure, into the ventricles where there is low pressure
backflow of blood into the veins is prevented by the closure of the valves in the veins
2 - ventricular systole
both ventricles contract forcing the blood up and out of the heart where there is higher pressure, into the arteries where there is lower pressure
the bicuspid and tricuspid valves close due to the pressure from the blood in the ventricles preventing the backflow of blood into the atria
the semilunar valves in the aorta and pulmonary artery open
3 - diastole
atria and ventricles relax creating a low pressure in the heart
semilunar valves in aorta and pulmonary artery close due to blood in the aorta where there is higher pressure, attempting to flow backwards into the ventricles where there is lower pressure
blood flows from the veins through the atria and into the ventricles as there is a higher pressure in the veins
what is stroke volume?
the volume of blood pumped from the left ventricle per beat
approx. 70mL in a healthy person
what is cardiac output?
the product of stroke volume and heart rate
how does stroke volume itself correlate with cardiac function?
because stroke volume decreases in certain conditions and disease states
give the summary of the cardiac cycle
the right atrium receives deoxygenated blood from the vena cavae and the left atrium receives oxygenated blood from the pulmonary vein
at this time, the atrioventricular valves are open: tricuspid in the right atrium and bicuspid in the left atrium
blood is drawn from the atria where there is higher pressure, into the ventricles which are relaxed and have low pressure
the atria contract which forces the remaining blood into the ventricles
the ventricles now contract, forcing the blood out via the semilunar valves through the pulmonary artery and aorta
both atria contract together and both ventricles contract together
a single heartbeat is one single contraction (systole) and relaxation (diastole)
why is the left ventricle thicker than the right?
it has to pump blood to all the parts and tissues to the body and hence needs thicker walls for more work to be done
when do the atrioventricular valves open and close in terms of the pressure changes of the heart?
they open when the pressure of the blood in the atria is greater than the ventricles
they close when the pressure of the blood in the ventricles is greater than in the atria
when do the semilunar valves open and close due to pressure changes in the heart?
they open when the pressure in the ventricles is greater than the aorta and pulmonary artery
they close when the pressure in these arteries is greater than the ventricles and blood tries to flow backwards
what is the effect of the pressure changes in the heart on arteries?
the highest pressure occurs in the aorta/arteries closes to the heart
there is a rhythmic rise and fall corresponding to ventricular contraction and relaxation
what is the effect of the pressure changes in the heart on arterioles?
friction with the vessel walls causes a progressive drop in pressure
arterioles have a large total cross-sectional area and a relatively narrow lumen causing a substantial decrease in aortic pressure
the pressure in the arterioles depends on whether they are dilated or constricted
what is the effect of the pressure changes in the heart on capillaries?
they have a small diameter and friction with the walls reduces flow rate of the blood and decreases pressure
as some fluid is forced out of the capillaries into the tissues, this further reduces blood flow and pressure in the capillaries
why is the mean pressure in the lung capillary lower than the muscle capillaries?
pressure is generated by the right ventricle which is thinner/weaker/less muscular than the left
reduced flow rate which allows more time for gas exchange and less tissue fluid produced
what is the effect of the pressure changes in the heart on veins?
the return flow to the heart is non-rhythmic as the veins are too far from the heart to be affected by its contraction and relaxation
the pressure in the veins is low but doesn’t fall to zero because of the massaging effect of the skeletal muscles
why is the heart myogenic?
means that the heartbeat is initiated from within the muscle itself and not due to external stimulation ie the brain
what are 6 steps of the control and production of the heartbeat?
in the wall of the right atrium is a region of specialised cardiac fibres called the sinoatrial node(SAN) which acts as a pacemaker
a wave of depolarisation(electrical impulse) arises at the SAN and electrical impulses spread over the two atria causing them to contract simultaneously
the electrical stimulation is prevented from spreading to the ventricles by a thin layer of connective tissues
this layer acts as a layer of insulation since the muscles of the ventricles mustn’t contract until the muscles of the atria have finished contracting
after a short delay, the nerve impulse reaches the atrioventricular node(AVN) which lies between the two atria
AVN passes on the impulse to the ventricles
from the AVN the impulse passes down the Bundle of His to the apex of the heart
the Bundle branches into Purkinje fibres in the ventricular walls which carry the wave of electrical impulse upwards through the ventricle muscle
the impulses cause the cardiac muscle in each ventricle to contract simultaneously from the apex upwards which forces the blood up and out of the heart
what does ECG stand for and what is it?
electrocardiogram and it is a trace/record produced by the procedure of electrical signals detected by electrodes
how can the electrical activity in the heart be detected?
by using electrodes placed on the skin
on what will the electrical signals detected by the electrodes be shown?
a cathode ray oscilloscope or chart recorder
what is the P wave?
the first part of the trace shows the depolarisation of the atria during atrial systole
what is the QRS wave?
shows the spread of depolarisation through the ventricles resulting in ventricular systole
what is the T wave?
represents relaxation and repolarisation of the ventricular muscle during ventricular diastole
what does the length of the PR interval indicate?
the time between the beginning of atrial contraction and the beginning of ventricular contraction
why is the QRS wave bigger than the P wave?
ventricles have more muscle than the atria so the amplitude is bigger than the P wave
what is arrhythmias?
irregular heartbeat
describe the heart rate and rhythm of arrhythmias compared to a normal trace
in atrial fibrillation, the heart rate is rapid, irregular and it may be difficult to distinguish a P/T wave
describe the change in the QRS wave from a person having a heart attack
a person who has had a heart attack may have a wide QRS
suggest the change in the QRS wave of a person with enlarged ventricle walls
they may have a QRS complex showing a greater range
