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OCR A-level Biology > Transport in Animals > Flashcards

Flashcards in Transport in Animals Deck (67)
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Why do animals need a transport system?

The need to supply cells with oxygen

Remove waste products

They are too large to perform these actions by simple diffusion (SA : V)


What are the 3 factors that influence the need for a transport system?


Surface area to volume ratio

Level of metabolic activity


How does size affect the need for a transport system?

If an organism is large the pathway for diffusion to their cells becomes too large

Therefore a transport system is required to supply cells with oxygen and to remove waste


How does surface area to volume ratio affect the need for a transport system?

When an organism has a low surface area to volume ratio the rate of diffusion is slow

Therefore it would take too long for oxygen to diffuse into the cells and so a transport system is required


How does the level of metabolic activity affect the need for a transport system?

Metabolic activity requires energy

Energy is produced in respiration

Aerobic respiration requires a lot of oxygen

Highly active organisms require lots of oxygen and thus need a transport system to provide it


What is a single circulatory system?

Where the blood flows through the hear once per circuit of the body


Give an example of a type of animal with a single circulatory system


Heart -> Gills -> Body -> Heart


What is a double circulatory system?

Where there are two different circuits performing different roles

One takes blood to the lungs to pick up oxygen

The other takes this oxygenated blood the working muscles


Describe the route of blood in a double circulatory system

Heart -> Lungs -> Heart -> Body -> Heart


What are the names of the two circuits in humans?

Pulmonary circuit

Systemic circuit


What are the advantages of a double circulatory system?

Can deliver the nutrients more quickly

The heart is able to increase the pressure of the blood after it has passed through the lungs so damage isn't caused to delicate capillaries

Can remove waste products more efficiently


What is an open circulatory system?

Where the blood is not always held in blood vessels

Instead the blood can flow freely through the body cavity


What are the disadvantages of open circulatory systems?

Blood pressure is low and blood flow is slow

Circulation of blood may be affected by movement or lack of movement


What is a closed circulatory system?

Where blood flows in specialised blood vessels


What are the advantages of a closed circulatory system?

High pressure so blood moves quickly

More rapid delivery of oxygen and nutrients

More rapid removal of CO2 and waste

Transport is unaffected by body movements


What is the name of the thin single cell layer on the inside of blood blood vessels?



Describe and explain the differences in structure between veins and arteries

Arteries have thick layer of smooth muscle and thick layers of collagen whereas veins have thinner layers of smooth muscle and collagen

Arteries have a narrow lumen to maintain high blood pressure whereas veins have a wider lumen to allow ease of flow

Veins have valves to prevent back flow of blood because the blood is maintained at a lower pressure. Arteries don't need this as the blood is much higher in pressure


What are the names of the 3 layers of an artery?

Tunica intima - a thin layer of elastic tissue

Tunica media - thick layer of smooth muscle

Tunica adventitia - Thick layer of collagen and elastic tissue


Describe the structure of capillaries?

Very narrow lumen - helps oxygen transfer as it reduces the diffusion distance

Very thin walls - consist of 1 layer of flattened endothelium, reduces diffusion distance

Walls are leaky - allows blood plasma and dissolved substances to leave the blood


What does blood plasma contain?

Carbon dioxide
Mineral ions
Amino acids
Clotting Factors

WBC's (leucocytes)


What is tissue fluid made of and how is it formed?

Similar to plasma but without any blood cells in it

Formed by plasma leaking out of the capillaries


What is hydrostatic pressure?

The pressure pushing out on the walls of a blood vessel from the blood inside


What is oncotic pressure?

The pressure from water trying to move into the blood vessel due to solute concentrations inside

Oncotic pressure opposes hydrostatic pressure


What's the function of the lymphatic system?

To drain excess tissue fluid out of the tissues and return it to the blood


How does the composition of lymph fluid differ to tissue fluid?

Lymph fluid contains more lymphocytes


Where are the lymphocytes in lymph fluid produced?

In the lymph nodes


At the arterial end of a capillary bed what is higher; hydrostatic pressure or oncotic pressure?

Hydrostatic pressure


At the venous end of a capillary bed what is higher; hydrostatic pressure or oncotic pressure?

Oncotic pressure


What is the role of the coronary arteries?

To supply oxygenated blood to the cardiac muscle


Which vessel delivers deoxygenated blood from the body to the hear?

Vena Cava


Which vessel delivers Oxygenated blood from the lungs to the heart?

Pulmonary vein


Which vessel delivers oxygenated blood from the heart to the rest of the body?



Which vessel delivers deoxygenated blood from the heart to the lungs?

Pulmonary artery


Which chamber does blood from the vena cava flow into?

Right atrium


Which chamber does blood from the pulmonary vein flow into?

Left atrium


What are there names of the valves which separate the atria and the ventricles

Atrio-ventricular valves


What chamber does the pulmonary artery take blood from?

Right Ventricle


What chamber does the Aorta take blood from?

Left Ventricle


What valves are found at the base of the arteries leaving the heart?

Semilunar valves


What is systole?

When the ventricles contract and force blood out of the heart


What is diastole?

After systole the ventricles and atria relax and the heart fill back up with blood


Where is the Sino-atrial node located?

In the right atrium


What is the role of Sino-atrial node (SAN)?

To act as the pacemaker by initiating a wave of excitation in the heart


Why does the bottom wall of the atria not conduct the wave of excitation but the side walls do?

To prevent the wave of excitation spreading to the ventricular walls too quickly which would cause an unsynchronised contraction


What is the name of the area by which the wave of excitation is able to pass from the atria to the ventricles?

The atrio-ventricular node (AVN)


Why does the atrio-ventricular node delay the wave of excitation?

To ensure that the ventricles don't contract too soon

This would cause an unsynchronised heartbeat leading to back-flow


What is the name of the tissue in the septum which carries the wave of excitation?

Purkyne tissue


What is the name of the graph showing electrical activity in the heart?

Electrocardiogram (ECG)


In an ECG, what does the P wave represent?

Excitation of the atria (atrial systole)


In an ECG, what does the QRS complex represent?

Ventricular systole


In an ECG, what does the T wave represent?



What is the name of the condition where someones heart rate is slower than normal?



What is the name of the condition where someones heart rate is faster than normal?



What is the name of the condition where someones heart rate is beating at irregular intervals?

Ectopic heartbeat


What would an ECG of a patient with atrial fibrillation look like?

No clear P wave (atrial systole)


What protein carry oxygen?



What gives haemoglobin its affinity for oxygen?

Fe2+ Prosthetic group


How many molecules of oxygen can be carried per molecule of Haemoglobin?



Describe the shape of the line on a graph showing saturation at different partial pressures of oxygen

Starts low and rises steeply as oxygen enters haemoglobin easily

As saturations reaches 100% the curve flattens off as it becomes harder to add oxygen against a concentration gradient


Compare the haemoglobin dissociation curves of adult and feral haemoglobin

Fetal haemoglobin has a higher affinity than adult haemoglobin

so fetal haemoglobin increases slightly quicker than adult haemoglobin

Still has the same S-shape


How is a majority of carbon dioxide transported in the body?

Hydrogencarbonate ions (HCO3^-)


Describe the formation of hydrogencarbonate ions

CO2 combine with water to form Carbonic acid (H2CO3)

Carbonic acid dissociates into HCO3- and H+


What is the name of the enzyme which catalyses the reaction between water and CO2 to form carbonic acid?

Carbonic anhydrase


What is the Chloride shift?

The movement of Cl- ions into the red blood cell as HCO3- ions move out

Aims to maintain a constant charge inside the cell


What is formed inside the red blood cell to prevent a build of of H+ ions (which could cause pH change)?

Haemoglobinic acid


What is the Bohr effect?

Describes the effect of CO2 concentration on the ability of haemoglobin to take up oxygen

At higher CO2 concentrations uptake is less effective


Why does the Bohr effect occur?

When CO2 combines with water in RBC's it forms carbonic acid

Carbonic acid dissociates to form H+ ions which lowers pH

this causes change in the shape of haemoglobin so it is less effective at holding oxygen