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A level Biology > Animal transport ( Component 3 ) > Flashcards

Animal transport ( Component 3 ) Flashcards

1
Q

Describe the vascular system of insects ( transport system )

A

Open circulatory system
Dorsal tube shaped heart
Fluid filled body cavity ( haemocoel )
Lack of respiratory gases in blood

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2
Q

What is open circulatory system ?

A

Transport medium pumped by the heart is not contained within vessels, but moves freely
Transport fluid comes into direct contact with the cells
Fluid bathes in tissues directly in a cavity called the haemocoel

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3
Q

Describe the vascular system of earthworms ( transport system )

A

Closed circulatory system, with blood under pressure
Vascularisation
Organs are not in direct contact with blood
Respiratory gases are transported in blood

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4
Q

What is a closed circulatory system ?

A

Blood pumped by the heart is contained within the vessels
Blood does not come into direct contact with the cells

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5
Q

Advantages of closed circulatory system compared to open circulatory system

A

Blood pressure can be maintained
Blood supply to different organs can vary
Lower volumes of transport fluid required

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6
Q

What is a single circulatory system ?

A

Blood travels through the heart only once
Blood travels in one circuit
Blood flows through the heart and is pumped around the body before returning to the heart

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7
Q

What is a double circulatory system ?

A

Blood travels through the heart twice in two circuits
Blood is pumped from the heart to the lungs before returning to the heart, it is then pumped around the body after which it returns back to the heart again

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8
Q

What type of circulatory system do fish have ?

A

Single circulatory system

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9
Q

What type of circulatory system do mammals have ?

A

Double circulatory system, double circulation where mammals have two atria and two ventricles

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10
Q

What are the benefits of a double circulatory system compared to a single circulatory system ?

A

Maintains blood pressure around the whole body
Uptake of oxygen is more efficient
Delivery of oxygen and nutrients is more efficient
Blood pressure can differ in pulmonary and systemic circuits

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11
Q

Name the 4 chambers of the mammalian heart ?

A

Left atrium
Right atrium
Left ventricle
Right ventricle

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12
Q

What are the five major blood vessels in the heart ?

A

Aorta
Vena cava
Pulmonary veins
Pulmonary arteries
Coronary arteries.

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13
Q

Describe the pathway of blood around the heart naming all the different structures

A

Pulmonary vein → Left atrium → Left ventricle → Aorta → Body → Venacava → Right atrium → Right ventricle → Pulmonary artery → Lungs

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14
Q

How is the heart a specialised organ ?

A

It has :
cardiac muscle
own blood supply
variation in thickness of walls
valves

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15
Q

Where are the atrioventricular valves found and what is their function ?

A

Found between atria and ventricles
Prevents backflow of blood from the ventricles into the atria

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16
Q

What are the two types of atrioventricular valves ?

A

Bicuspid ( left )
Tricuspid ( right )

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17
Q

Where are the semilunar valves found and what is their function ?

A

Found between the ventricles and the arteries
Prevent the backflow of blood from arteries into ventricles

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18
Q

Name the 5 types of blood vessel

A

Arteries
Arterioles
Capillaries
Venules
Veins

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19
Q

Describe the pathway of blood through the blood vessels

A

Heart → arteries → arterioles → capillaries → venules → veins → heart

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20
Q

What are the three main layers in large vessels ?

A

Tough collagen outer layer
Elastic muscular layer to sustain pressure
Endothelium which is smooth to reduce friction; capillary walls are one cell thick.

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21
Q

What is the function of arteries ?

A

Carry blood away from heart to tissues, under high pressure

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22
Q

Relate the structure of the arteries to their function

A

Thick muscular walls to handle high pressure without tearing
Elastic tissue allows recoil to prevent pressure surges
Narrow lumen to maintain pressure

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23
Q

What is the function of the veins ?

A

Carry blood towards the heart under low pressure

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24
Q

Relate the structure of veins to their function

A

Thin walls due to lower pressure
Require valves ( semi lunar ) across the length of the vein to prevent back flow of blood
Have less muscular and less elastic tissue as they don’t have to control blood flow.

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25
What is the function of the capillaries ?
Form a large network through the tissues of the body and connect the arterioles to the venules
26
Relate the structure of capillaries to their function
Walls are one cell thick so short diffusion distance Very narrow so can permeate tissues and red blood cells can lie flat against the wall, reducing the diffusion distance Numerous and highly branched, providing a large surface area Small diameter and friction with the walls slows the blood flow There are many capillaries in the capillary bed, providing a large total cross-sectional area which further reduces blood flow. This low velocity in very thin walled vessels enhances their ability to exchange materials with the surrounding tissue fluid.
27
What is the function of arterioles ?
Connect the arteries and the capillaries Arterioles adjust diameter to adjust blood supply
28
What is the function of the venules ?
Connect the capillaries and the veins
29
Relate the structure of arterioles and venules to their function
Branch off arteries and veins in order to feed blood into the capillaries Smaller than arteries and veins so that the change in pressure is more gradual as blood flows into the capillaries.
30
What is meant by the cardiac cycle ?
The cardiac cycle refers to a sequence of events which takes place during the beating of the heart ( one complete contraction and relaxation of the heart ) Three stages include : atrial systole, ventricular systole and ventricular diastole
31
5 stages of the Cardiac cycle
1) Blood enters the atria from the vena cava and pulmonary veins, AV valves open , SL valves closed 2) Atria contracts, volume of blood decreases and pressure increases, blood enters the ventricles down a pressure gradient, AV valves open, SL valves closed ( atrial systole ) 3) Blood enters the ventricles through the AV valves, low pressure in ventricles, AV valves open, SL valves closed 4) Ventricles contract, volume of blood decreases and pressure increases Av valves closed, SL valves open ( ventricular systole ) 5) Blood forced through SL valves into aorta and pulmonary artery, Av valves closed, SL valves open
32
What happens during atrial systole ?
Atria contract, pushing any remaining blood into the ventricles AV valves pushed fully open
33
What happens during ventricular systole ?
Ventricles contract, pressure in ventricles increases, closing the AV valves to prevent backflow and opening the SL valves. Blood flows into the arteries
34
What happens during ventricular diastole ?
Heart is relaxed. Blood enters the atria, increasing the pressure and pushing open the AV valves. This allows blood to flow into the ventricles. Pressure in heart is lower than pressure in arteries, so SL valves remain closed.
35
Why is cardiac muscle described as myogenic ?
It initiates its own contraction without outside stimulation from nervous impulses
36
Explain how the heart contracts ( electrical control )
1) The sinoatrial node (SAN) initiates a wave of excitation ( electrical impulses ) 2) This spreads over the walls of the atria causing them to contract ( atrial systole ) 3) It is prevented from spreading to the ventricles by a thin layer of connective tissue that is non conductive 4) The electrical impulses reach the atrioventricular node ( AVN ). The wave of excitation is delayed through this node which allows complete contraction of the atria before the ventricles start to contract 5) The wave of excitation then travels down highly conductive tissue in the septum ( " bundle of His " ). As it reaches the base of the ventricles it causes the ventricles to contract as it travels through the purkinje fibres up the side of the ventricles from the apex upwards ( ventricular systole ) 6) The heart then goes into a period of relaxation called " diastole " as the electrical impulse is terminated as there is no conductive tissue.
37
Where are the highest pressures of blood found when blood leaves the heart ? What do they show ?
Found in the aorta and main arteries which show a rhythmic rise and fall which corresponds to ventricular contraction.
38
What does friction of blood with vessel walls cause ?
Progressive blood pressure drop
39
Why do arterioles cause substantial reduction from aortic pressure ? What does the pressure in the arterioles depend on ?
Arterioles have a large total surface area and relatively narrow bore which causes substantial reduction from aortic pressure. Their pressure depends on whether they are dilated or contracted.
40
Why does blood pressure fall across a capillary / capillaries and in capillary beds ( larger resistance ) ?
They have a large cross sectional area Lower volume of blood Friction
41
What does the velocity of blood flow relate to ?
The velocity of blood flow is directly related to the pressure. In the capillary beds the pressure drops further due to leakage from capillaries into tissues
42
Is the flow of blood returning to the heart rhythmic or non rhythmic ?
Non rhythmic
43
Is the blood pressure in veins high or low and how can it be increased ?
Return flow to the heart is non-rhythmic and the pressure in the veins is low but can be increased by the massaging effect of muscles.
44
What is an ECG ( electrocardiogram ) ?
A graph showing the electrical activity of the heart during the cardiac cycle. The electrical activity that spreads through the heart during the cardiac cycle can be detected using electrodes placed on the skin. The electrical signals can then be shown on a cathode ray oscilloscope or a chart recorder. The record produced by this procedure is called an electrocardiogram (ECG)
45
Explain the characteristic patterns displayed on a typical ECG
The P wave shows the depolarisation of the atria during atrial systole. The QRS wave shows the spread of depolarisation through the ventricles resulting in ventricular systole. The T wave shows the repolarisation of the ventricles during ventricular diastole.
46
Describe the function and structure of erythrocytes ( eg RBCs )
Type of blood cell that is anucleated and biconcave. Contains haemoglobin which enables the transport of oxygen and carbon dioxide to and from the tissues
47
What is the role of haemoglobin ?
Present in RBCs Oxygen molecules bind to haem groups and are carried around the body, then released where they are needed in respiring tissues
48
How does the partial pressure of oxygen affect oxygen - haemoglobin binding ?
At high p(O2) : oxygen associated to form oxyhaemoglobin ( high affinity ) At low p(O2) : oxygen dissociated to form deoxyhaemoglobin ( low affinity )
49
What is the equation for the formation of oxyhaemoglobin ?
Hb + 4O2 ⇌ Hb.402
50
What do oxyhaemoglobin dissociation curves show ?
Saturation of haemoglobin with oxygen (%), plotted against partial pressure of oxygen (kPa). Curves further to left show that the haemoglobin has a greater affinity for oxygen.
51
Explain the shape of oxyhaemoglobin dissociation curves
Sigmoidal shape ( S shaped ) When the first O2 molecule binds, it changes the tertiary / quaternary structure so that it is easier for the second and third molecules to bind. Third molecule changes tertiary structure of haemoglobin so that it is more difficult for the fourth molecule to bind
52
How does fetal haemoglobin differ from adult haemoglobin ? Why is the higher affinity of fetal haemoglobin important ? Compare the dissociation curves of adult and fetal haemoglobin
Fetal haemoglobin has a higher affinity than adult haemoglobin due to the presence of two different subunits that allow oxygen to bind more readily. Higher affinity enables fetus to obtain oxygen from the mother's blood Fetal haemoglobin dissociation curve is to the left of adult haemoglobin curve - at same partial pressure, % oxygen saturation is greater
53
Compare the dissociation curves of adult and fetal haemoglobin, myoglobin, llama haemoglobin and lugworm haemoglobin
Left to right : Myoglobin, llama haemoglobin, human fetal haemoglobin, human maternal haemoglobin
54
State what is meant by the Bohr effect
The loss of affinity of haemoglobin for oxygen as the partial pressure of carbon dioxide increases. ( curve moves to the right ). The release of oxygen involves the Bohr effect where the lowered pH due to dissolved carbon dioxide reduces the oxygen affinity of haemoglobin, causing it to release oxygen where it is most required
55
Explain the effect of carbonic anhydrase in the Bohr effect
Carbonic anhydrase is present in all red blood cells Catalyses the reaction of carbon dioxide and water to form carbonic acid, which dissociates to produce H+ ions H+ ions combine with the haemoglobin to form haemoglobinic acid Encourages oxygen to dissociate with haemoglobin
56
How is carbon dioxide carried from respiring cells to the lungs ?
Transported in aqueous solution in the plasma As hydrogencarbonate ions in the plasma Carried as carbaminohaemoglobin
57
What is the chloride shift ?
Process by which chloride ions move into the erythrocytes in exchange for hydrogencarbonate ions which diffuse out of the erythrocytes, via faciliated diffusion One to one exchange
58
Why is the chloride shift important ?
It maintains the electrochemical equilibrium of the cell.
59
What is the function of carbonic anhydrase ?
Catalyses the reversible reaction between water and carbon dioxide to produce carbonic acid
60
Write the two equations that show the formation of hydrogen carbonate ions in the plasma
Carbonic anydrase catalyses : H2O + CO2 ⇌ H2CO3 ( carbonic acid ) Carbonic acid dissociates : H2CO3 → H+ + HCO3-
61
Explain what is meant by the Bohr effect
the increased H+ from carbonic acid decreases the affinity of haemoglobin for oxygen. Oxyhaemoglobin binds H+ and releases oxygen which diffuses out of the red blood cells into the tissues.
62
What is plasma ?
Main component of blood ( yellow liquid ) that carries red blood cells Contains proteins, nutrients, mineral ions, hormones, dissolved gases and waste. Also distributes heat.
63
What are the two main roles of plasma ?
Transports digested food products, hormones, proteins, albumin, fibrinogen, antibodies and ions . Also distributes heat.
64
What is tissue fluid ?
Fluid that surrounds the cells of animals Same composition as plasma but does not contain red blood cells or plasma proteins
65
Describe the different pressures involved in the formation of tissue fluid
Hydrostatic pressure = higher at arterial end than of capillary than venous end Oncotic pressure = changing water potential of capillaries as water moves out, induced by plasma proteins
66
How is tissue fluid formed ?
Blood is pumped through increasingly smaller vessels Hydrostatic pressure is greater than oncotic pressure Fluid moves out of capillaries It then exchanges substances with the cells
67
Why does blood pressure fall along a capillary ?
Friction / resistance of the walls Lower volume of blood
68
What happens at arterial end of capillary ?
Hydrostatic pressure is higher than osmotic pressure and so water and small soluble molecules are forced out through the capillary walls, forming tissue fluid between the cells. Proteins and cells in the plasma are too large to be forced out.
69
What happens at venous end of capillary ?
Oncotic pressure is greater than hydrostatic pressure Fluid moves down its water potential gradient back into the capillaries
70
Where does some tissue fluid drain ?
Some tissue fluid drains into the lymphatic system and eventually returns to the blood

A level Biology (10 decks)

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