Adaptations for Transport: Animals Flashcards
where are open circulatory systems found?
In insects
What is the process of an open circulatory system?
-Fluid is pumped at relatively low pressure from one long, dorsal (top) tube-shaped heart running the length of the body
-Fluid called haemolymph bathed with tissues 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
where are two places a closed circulatory system is found?
-Mammals and fish
-Earth worms
what is the closed circulatory system in mammals and fish?
-blood circulate 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 contains a respiratory pigment, which carries oxygen
What is the circulatory system in earthworms?
-has dorsal and ventral vessels running the length of the body
-These are connected by five pairs of pseudohearts
-Blood contains a respiratory pigment, which carries oxygen
What is the blood pressure like in an open circular system?
-Blood is under low pressure as it is not contained within vessels
has haemolymph got direct contact with organs in an open circulatory system?
yes- as haemolymph leaves the circulatory system it bathes organs directly
where is blood contained in an open circulatory system?
-Blood is pumped from a long, dorsal (top) tubular heart into spaces within the body cavity
why is respiratory pigment to carry oxygen not needed for an open circulatory system ?
oxygen reaches the gas exchange surface via a tracheal system
Where is oxygen transported in an open circulatory system?
oxygen is transported directly to tissues
what is the blood pressure like in a closed circulatory system?
-Blood is under high-pressure, as it is contained within blood vessels
why does blood never have direct contact with organs in a closed circulatory system?
blood is contained within the blood vessels
where is blood contained in a closed circulatory system?
Vessels which include arteries, veins and capillaries
what is the respiratory pigment a closed circulatory system?
-oxygen diffuses into the blood, and is carried around the body in blood bound to haemoglobin (respiratory pigment)
how is oxygen transported in a closed circulatory system?
-oxygen is transported from the lungs to the heart and then the capillaries in the body tissues
What is meant by single circulation?
blood passes through the heart once in one complete circulation
What is meant by a double circulation system?
Blood passes through the heart twice in one complete circulation
Where does single circulation occur?
Fish
What does double circulation occur?
mammals
What are the two circuits in double circulation?
-pulmonary circulation
-Systematic circulation
What is pulmonary circulation?
-All the blood vessels involved in transporting all the blood from the heart to the lungs
what is systematic circulation?
all of the blood vessels involved in transporting blood from the heart to the rest of the body/tissues (excluding the lungs)
what is the circulation type in an insect?
-Open
What is the circulation type in an earthworm?
-Closed
-Single
what is the circulation type in a fish?
-closed
-single
what is the circulation type in a mammal?
-Closed
-double
what animal does not have respiratory pigment?
An insect
what is the heart in an insect?
-dorsal tube shaped
what is the heart in an earth worm?
pseudohearts
what is the heart in a mammal?
-2 atria
-2 Ventricles
What is the heart of a fish?
-1 atria
-1 ventricle
What are the advantages of a double circulation system?
-maintains a high blood pressure in the systematic (body) circulation (higher pressure to body cells)
-allows for a lower pressure in the pulmonary (lung) (at alveoli)
-rapid circulation in the systematic circuit
-higher rate of blood flow
what does the advantage of maintaining high blood pressure in the systematic circulation mean? (double circulation)
-Increases rate of flow to the tissues, so therefore an increased rate of oxygen to tissues for aerobic respiration
what is the advantage of allowing for lower pressure in the pulmonary circulation mean? (double circulation)
if the pressure was too high tissue fluid buildup in the lungs
what is the advantage of rapid circulation in the systematic circuit mean? (double circulation)
-oxygen and other nutrients can be transported to all the body’s tissues quickly and waste (e.g. Carbon dioxide) can also be removed from tissues quickly
why is it important that the oxygenated and the deoxygenated blood is kept separate in a double circulation system?
maintains a steep concentration gradient for oxygen at the tissues and carbon dioxide in the lungs for efficient exchange
What does the transport system in mammals consist of?
-Closed double circulatory system
what are the three types of major blood vessels that make up the circulatory system?
-Arteries
-veins
-Capillaries
What do arteries do?
Transport blood away from the heart
what do veins do?
Transport blood to the heart
what are capillaries?
Smallest vessels that allow exchange of substances
what are the features in arteries and veins?
-Tunica externa
-Tunica media
-Tunica intima
-Endothelium (one cell thick)
-Lumen
What is the size of an artery?
0.1-25mm
what is the size of a vein?
1-15mm
What are the features of an capillary?
endothelium (one cell thick)
What is the size of the capillary?
5-10 um
What is the endothelium?
-Th innermost layer of the vessel and is one cell thick
-It provides a smooth lining
why is the endothelium providing a smooth lining an important feature?
-reduces friction to reduce resistance to blood flow
-In capillaries, being one cell thick provides a short diffusion distance
what is the tunica externa made up of?
collagen fibres
what is the tunica media made up of?
-Elastic fibres and smooth muscle
What do the elastic fibres and smooth muscle make up?
These components make up the middle layer of the vessel
in which blood vessel is the elastic fibre and smooth muscle layer thicker?
arteries
what is the function of smooth muscle in arteries?
-Allows arteries to withstand high blood pressure produced by the pumping action of the heart -
contracts (vasoconstriction) or relaxes (vasodilation) to direct blood flow to tissues
What is the function of elastic fibres in arteries?
-stretch and recoil to maintain a high blood pressure
What are collagen fibres?
these fibres are found in the outer layer of the vessels and are resistant to over-stretching
Why do veins have wide diameter lumens?
So they can deliver large volumes of blood back to the heart
Why do veins have thin walls?
As the pressure inside is much lower, due to the further distance from the heart
What can be done with the thin muscle layer in the walls of the veins?
they can be compressed easily, allowing contracting skeletal muscle to squeeze veins and push the blood upwards towards the heart
What do pocket valves in the veins do?
ensure that blood flows in one direction (towards the heart)
How do pocket valves work?
-blood tried to flow back
-blood fills the pocket above the valve
-this forces the valve to shut
why do veins above the heart have no valves?
-gravity will draw the blood down towards the heart
why do arteries have a thick layer of smooth muscle?
to withstand high pressure blood
why do arteries have a thick layer of elastic fibres?
For elastic recoil to maintain high blood pressure
What do arterioles do?
they are able to adjust the diameter to vary the blood supply to a capillary bed
What do capillary walls only consist of?
an endothelium and are one cell thick
what do some capillaries have in their walls?
pores
What are capillary walls permeable to?
-water and dissolve substances such as glucose, amino acids, urea, oxygen and carbon dioxide
why do thin capillary walls allow for more efficient exchange of materials and gases?
as there is a shorter diffusion pathway and the large cross-sectional area
what does capillaries having a narrow lumen do?
restricted blood flow, slowing down the blood to allow more time for gas exchange of materials at the tissues (blood cells must distort past through)
what happens as velocity falls in the capillaries?
Blood pressure decreases
Why does the left side of a heart have a thicker wall?
-It is more muscular, so it can contract with more force
why is the atria wall thin?
-atria wall only pumps blood to the ventricle
what is the function of the tendinous cords in the heart?
-when ventricles contract, the increased blood pressure causes the AV valves to close simultaneously, preventing the backflow of blood into the atria
-The tendinous cords prevent the valves inverting into the atria
what is the aorta?
Largest artery and transports blood from the heart to the body
what is the vena cavae?
two veins that carry deoxygenated blood to the heart from the upper and lower parts of the body
what do the pulmonary arteries do?
-Transport deoxygenated blood from the heart to the lungs, where gas exchange takes place
What do pulmonary veins do?
transport oxygenated blood from the lungs back to the heart
What do you coronary arteries do?
Supply the heart cells with oxygenated blood and glucose
what do the coronary veins do?
remove deoxygenated blood from the cardiac muscle
How does blood flow through the heart and around the body?
-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 ventricle through the bicuspid valve
-The ventricle contracts and the bicuspid valve closes, forcing blood upwards into the aorta through the semi-lunar valve
-oxygenated blood leaves the heart to via the aorta to travel to the body tissues
-deoxygenated blood from the body returns to the heart tissues in the vena cava
-The deoxygenated blood moves from the superior and inferior vena cava to the atrium
-The right atrium contracts and blood moves into the right ventricle through the tricuspid valve
-The right ventricle contracts, closing the tricuspid valves, and forcing blood into the pulmonary artery through the semilunar valve
-Deoxygenated blood travels in the pulmonary artery towards the lungs
What are the three stages of the cardiac cycle?
-atrial systole
-ventricular systole
-diastole
what is the stage of atrial systole?
-Both atria contract, forcing the tricuspid and bicuspid valves open
-blood flows from atria (high pressure) into the ventricles (lower pressure)
-Backflow of blood into the veins is prevented by closure of the valves in the veins
What is the stage of ventricular systole?
-both ventricles contract, forcing the blood up and out of the heart (high pressure) into the arteries (lower pressure)
-The bicuspid and tricuspid valves close due to the pressure from the blood in the ventricles .
-This prevents the backflow of blood
-The semi valves in the aorta and pulmonary artery are open
what is the stage of diastole?
-atria and ventricles relax creating a low pressure in the heart
-The semi valves in the iota and pulmonary artery close due to the blood in the aorta (higher pressure) attempting to flow backwards into the ventricles (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 (approximately 70 mL in a healthy person)
What is cardiac output?
The product of stroke value and heart rate
Why does stroke volume itself correlate with cardiac function?
because stroke volume decreases in certain conditions and disease states
why can the description of the cardiac cycle begin at any stage?
It is a continuous process
what is the summary of the cardiac cycle?
1.The right atrium receives deoxygenated blood from the Vena cavae and the left atrium receives oxygenated blood form the pulmonary vein
2. At this time, the atrioventricular valves are open: tricuspid in the right atrium and bicuspid in the left atrium.
3. Blood is drawn from the atria (higher pressure) into the ventricles which are relaxed (lower pressure).
4. The atria contract which forces the remaining blood into the ventricles. 5.The ventricles now contract, forcing the blood out via the semi lunar 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 does the left ventricle have a thicker muscular wall and than the right ventricle?
The left ventricle has a thicker muscle wall than right ventricle and therefore produces higher pressure as the left ventricle pumps blood to the body, in order to move blood such a large distance. The right ventricle pumps blood to the lungs- a shorter distance from the heart so lower pressure needed.
When are the tricuspid and bicuspid valves (atrio-ventricular vales) open?
When the pressure of the blood is greater in the atria than in the ventricles
When are the tricuspid and bicuspid valves (atrio-ventricular vales) closed?
When the pressure of the blood in the ventricles is greater in the atria
When are the semi lunar valves open?
when the pressure in the ventricles is greater than the aorta and pulmonary artery
when do the semi lunar valves close?
when the pressure in these arteries is greater than ventricles and blood tries to flow backwards
where does the highest pressure occur? (blood pressure changes in the vessels)
-in the aorta/arteries closest to the heart
-there is a rhythmic rise and fall, corresponding to ventricular contraction and relaxation
What happens to the pressure in the arterioles? (blood pressure changes in the vessels?
-friction with vessel walls cause of progressive drop in pressure
-Arterioles have a large cross-sectional area and a relatively narrow and causing a substantial decrease in aortic pressure
What does the pressure in the arterials depend on?
whether they are dilated or constricted
what is the pressure like in the capillaries? (blood pressure changes in the vessels)
-capillaries have a small diameter and friction with the walls reduce 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?
-Reduced flow rate- allows more time for gas exchange
-Less fluid tissue produced
what is pressure like in the veins? (blood pressure changes in the vessels)
-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 0 because of the massaging effect of skeletal muscles
what is the heart muscle? (control of heartbeat)
myogenic i.e. The heartbeat is initiated from within the muscle itself and he’s not due to external stimulation
What is the process of control of heartbeat?
In the wall of the right atrium is a region of specialised cardiac fibres called the sino-atrial node (SAN) which acts as a pacemaker.
2. A wave of depolarisation (electrical impulse) arises at the SAN and nerve impulses spread over the two atria causing them to contract simultaneously.
3. The electrical stimulation is prevented from spreading to the ventricles by a thin layer of connective tissue. This acts as a layer of insulation (it is important that the muscles of the ventricles do not start to contract until the muscles of the atria have finished contracting).
4. After a short delay the nerve impulse reaches the atrio-ventricular node (AVN), which lies between the two atria. This 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 depolarisation upwards through the ventricle muscle.
6. The impulses cause the cardiac muscle in each ventricle to contract simultaneously from the apex upwards. This forces blood up and out of the heart.
How can the electrical activity that spreads to do the heart during the cardiac cycle be detected? (ecg traces)
Using electrodes placed on the skin
how can the electrical signals (from the electrodes) then be shown, and what is the record produced by this procedure called?
-they can then be shown on a cathode rate oscilloscope or a chart recorder
-the record produced by this procedure is called an electrocardiogram (ECG)
what is a p wave? (ecg traces)
The first part of the trace shows the depolarisation of the atria during atrial systole
What does the QRS wave show?
The spread of the polarisation through the ventricles, resulting in ventricular systole
What does the T wave represent?
relaxation and repolarisation of the ventricular muscle during ventricular diastole
what does the length of the PR interval indicate? (ecg traces)
The time taken for the excitation to spread from the atria to the ventricles via the AV node
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
how is heart rate calculated?
-length of the cycle= time taken between equivalent points of the trace
heart rate= 60/cycle length
what would an irregular heart rate look like? (ecg traces)
-rapid, irregular, and lacks a of p wave
what would the change in the QRS wave from a person having a heart attack?
Wide QRS complex
what would the change in the QRS of a person with enlarged ventricle walls be?
-May have a QRS complex showing greater voltage range
How is cardiac output calculated?
heart rate x stroke volume
what is haemocoel?
-Space in an insect body cavity that fluid is pumped into
What is haemolymph?
The fluid in insects that bathes the tissues directly, enabling the exchange of substances
What are chordae tendinae?
tendons attached to the valves in the heart which prevent the valves from prolapsing
what are atrioventricular valves?
Valves between atria and ventricles
What are semi lunar valves?
Valves between major arteries and ventricles
what is the sino atrial node?
pacemaker found in the wall of the right atrium, which sends a wave of depolarisation across the atrium
what is the atrial ventricular node?
bundle of tissue found between the atria and ventricles which delays the wave of depolarisation
what is the bundle of His?
-fibres which transmit the wave of the depolarisation through the septum to the Apex
what are the Purkinje fibres?
fibres which transmit the wave of depolarisation into the ventricular walls to allow contraction
what is systole?
Scientific term for contraction
What is diastole?
Scientific term for relaxation
What is an electrocardiogram?
A test used to check the hearts rhythm and electrical activity
