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A-Level Biology - Three > 8.1-5 Transport in animals > Flashcards

8.1-5 Transport in animals Flashcards

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1
Q

What are the five basic structures of arteries, arterioles, venules and arteries?

A

Tough collagen outer layer - provides structural support to maintain shape of vessel and resist pressure

Smooth muscle layer - can contract and relax to control the flow of blood by changing the size of lumen

Elastic layer - can stretch and recoil to maintain blood pressure, contains elastin

Endothelium - inner lining of cells, a smooth layer to prevent friction and thin for a short diffusion pathway (in the case of capillaries)

Lumen - not a layer, a cavity which blood flows through

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2
Q

What is the function of arteries?

A
  • to transport blood rapidly at high pressure away from the heart to tissues
  • most carry oxygenated blood (except the pulmonary artery)
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3
Q

What is the structure of arteries?

A

Thick muscle layer - control the flow of blood via constricting and dilating (contracting)

Thick elastic layer - to allow stretching under high blood pressure when ventricle contracts and recoils under low blood pressure when ventricles relaxes to withstand and maintain high pressure and to smooth blood flow during pressure surges created by the beating heart

Smooth endothelium - reduces friction to allow blood to flow easily

Overall very thick wall - withstands high pressure to prevent burning

No valves - blood always at high pressure due to heart pumping and so blood doesn’t naturally flow backwards

Collagen - thick collagen layer to maintain shape of vessel and prevent it stretching too much, it also helps to withstand high pressure

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4
Q

What is the function of arterioles?

A
  • to transport blood from arteries to capillaries
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5
Q

What is the structure of arterioles?

A

more smooth muscle than arteries (relative to their size) = to allow vasoconstriction to reduce blood flow before entering the capillaries

thinner elastic layer than arteries (relative to their size) = as blood pressure is lower in arterioles

smaller in diameter

no valves

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6
Q

What is the function of capillaries?

A
  • to exchange metabolic substances between blood and body tissues
    example = very slow blood flow, and single file red blood cells
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7
Q

What is the structure of capillaries?

A

overall very thin wall - one cell thick endothelium for short diffusion pathway

numerous and branched - large surface area for exchange

narrow diameter - can permeate tissues so no cell is far away from capillary (short diffusion pathway), forces red blood cells to move slowly in single file to allow time for diffusion to take place, also allows for greater surface area of red blood cell to be in contact with the capillary wall to help make diffusion more efficient by decreasing the diffusion pathway

Spaces between endothelial cells - allows white blood cells to leave blood and enter tissues fluid, also allows exchange of some substances

Total cross-section area of capillaries is greater than the arteriole supplying them - this makes the rate of blood flow decrease, giving more time for exchange substances

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8
Q

What is the function of venules?

A
  • to transport blood slowly at low pressure from capillaries to veins
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9
Q

What is the structure of venules?

A

very thin muscle layer - as they don’t control the flow of blood via constricting and dilating

very thin elastic layer - as blood pressure is low and so veins do not need to stretch and recoil

valves - to prevent backflow of blood (when they get compressed when muscles contract) as blood is always at low pressure

smooth endothelium - reduces friction to allow blood to flow easily

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10
Q

What is the function of veins?

A
  • to transport blood at low pressure from venules to the heart
  • most carry deoxygenated blood (except the pulmonary vein)
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11
Q

What is the structure of veins?

A

thin muscle layer - as they don’t control the flow of blood via constricting and dilating

thin elastic layer - as blood pressure is low and so veins do not need to stretch and recoil

overall thin wall - no need to withstand high pressure and so no risk of bursting, allows compression which aids blood flow

do not have a pulse - the surges of blood are lost as the blood passes through the narrow veins

valves - to prevent backflow of blood (when they get compressed when muscles contract) as blood is always at low pressure

smooth endothelium - reduces friction to allow blood to flow easily

collagen - thick collagen layer to maintain shape of vessel as veins carry large volumes of blood

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12
Q

What are the two types of circulatory systems?

A
  • open
  • closed
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13
Q

Where is the blood confined in mammals and fish?

A
  • blood vessels
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14
Q

Explain the double closed circulatory system in both single and double form.

A
  • single = heart with two chambers meaning the blood passes through the heart once for every circuit of the body
  • double = heart has four chambers and blood passes through the heart twice for every circuit of the body
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15
Q

Define tissue fluid.

A
  • a liquid containing dissolved oxygen and nutrients which serves as a means of supplying the tissues with the essential solutes in exchange for waste products such as carbon dioxide
  • enables exchange of substances between blood and cells
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16
Q

What is the process of hydrostatic pressure?

A
  • created when blood is pumped along the arteries, into arterioles and then capillaries
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17
Q

What do hydrostatic pressure cause?

A
  • forces blood out of the capillaries
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18
Q

What does oncotic pressure do?

A
  • pushes some of the fluid back into the capillaries
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19
Q

Which parts of the circulatory system has different water potentials?

A
  • capillaries have negative water potential due to how the blood and tissue fluid contain solutes
  • blood is less negative than caps due to more solutes
  • tissue fluid has positive water potential due to how water moves down the water potential gradient from the tissue fluid to the blood by osmosis
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20
Q

Where does the rest of the tissue fluid remaining go?

A
  • not pushed back into the capillaries
  • carried back via the lymphatic system
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21
Q

What does the lymphatic system contain?

A
  • lymph fluid
22
Q

What does tissue fluid contain?

A
  • less oxygen and nutrients compared to tissue fluid
  • as its main purpose is to carry waste products
  • lymph nodes
23
Q

What are lymph nodes?

A
  • filter out bacteria and foreign material from the fluid with the help of lymphocytes which destroy the invaders as part of the immune system defences
24
Q

What is the word called that explains the hearts ability to initiate its own contraction?

A
  • myogenic
25
Q

What is in the walls of the right atrium?

A
  • specialist fibers called the sinoatrial node
  • pacemaker of the heart
  • initiates a wave of electrical stimulation which causes the atria to contract at roughly the same time
26
Q

When do the ventricles contract?

A
  • do not start contracting until the atria have finished due to the presence of tissue at the base of the atria which is unable to conduct the wave of excitation
27
Q

What does the electrical wave reach after SVN?

A
  • atrioventricular node
  • located between the two atria which passes on the excitation to ventricles down the bundle of his to the apex of the heart
28
Q

What does the bundle of his attach to?

A
  • purkyne fibers which carry the wave upwards
  • cause ventricles to contract
29
Q

What are the three stages of the cardiac cycle?

A
  • atrial systole
  • ventricular systole
  • cardiac diastole
30
Q

What is the atrial systole?

A
  • during the atrial systole the atria contract (both)
  • this forces the atrio-ventricular valves open and blood flows into the ventricles
31
Q

What is the ventricular systole?

A
  • contraction of the ventricles causes the atrio-ventricular valves to close
  • semi-lunar valves to open thus allowing blood to leave the left ventricle through the aorta and right ventricle through the pulmonary artery
32
Q

What is the cardiac diastole?

A
  • atria and ventricles relax
  • elastic recoil of the heart lowers the pressure inside the heart chambers
  • blood is drawn from the arteries and veins
  • causing semi-lunar valves in the aorta and pulmonary arteries to close preventing backflow of blood
33
Q

What is haemoglobin?

A
  • a water soluble globular protein which consists of two alpha and two beta polypeptide chains each containing a haem group
34
Q

What does haemoglobin do?

A
  • carries oxygen in the blood as oxygen can bind to the haem (Fe 2+) group and oxygen is the released when required
  • each molecule can carry four oxygen molecules
35
Q

What happens in relation to affinity of oxygen?

A
  • varies depending on the partial pressure of oxygen which is a measure of oxygen concentration
36
Q

What is concentration in relation to oxygen in cells?

A
  • the greater the concentration of dissolved oxygen in cells the greater the partial pressure
37
Q

If the partial pressure were to increase, how does this relate to the affinity of oxygen?

A
  • the affinity of haemoglobin for oxygen increases
  • that is oxygen binds to haemoglobin tightly
38
Q

Where is the body does increased affinity of haemoglobin and oxygen?

A
  • occurs in the lungs in the process called loading
39
Q

What happens during respiration relating to the affinity of oxygen?

A
  • oxygen is used up = partial pressure decreases = decreasing the affinity of oxygen for haemoglobin
  • oxygen is released in respiring tissues where it is needed
40
Q

What happens after the unloading process?

A
  • the haemoglobin returns to the lungs where it binds to oxygen again
41
Q

What do the dissociation curves present?

A
  • change in haemoglobin saturation as partial pressure changes
42
Q

What is the saturation of haemoglobin affected by?

A
  • its affinity for oxygen
  • therefore when partial pressure is high, haemoglobin has high affinity for oxygen and is highly saturated and vice versa
43
Q

What can saturation also affect?

A
  • affinity
  • as after binding to the first oxygen molecule affinity of haemoglobin for oxygen increases due to change in shape
  • making it easier for the other oxygen molecules to bind
44
Q

What is fetal haemoglobin?

A
  • has different affinity for oxygen compared to adult haemoglobin
  • needs to be better at absorbing oxygen because by the time oxygen reaches the placenta
  • the oxygen saturation of the blood has decreased
  • must have high affinity for oxygen in order for the fetus to survive at low partial pressure
45
Q

What can the affinity of haemoglobin for oxygen also be affected by?

A
  • the partial pressure of carbon dioxide
  • presence of CO2 affinity of haemoglobin for oxygen decreases causing oxygen to be released = Bohr effect
46
Q

Where is carbon dioxide used?

A
  • released by respiring cells which require oxygen for the process to occur
47
Q

What is meant by diastole?

A
  • period of relaxation
  • atria and then ventricles fill with blood
  • volumes and pressures of the blood in the heart increases but is low in the arteries
48
Q

What is meant by systole?

A
  • period of contraction
  • pressure of blood inside heart increases quickly and blood is forced out of the both sides of the heart
  • by end of systole blood pressure inside the heart is very low and is high in arteries
49
Q

What are the two types of valves?

A
  • atrioventricular valves
  • semi-lunar valves
50
Q

What are the atrioventricular valves?

A
  • between atria and ventricles
  • prevent backflow of blood from ventricles contract and atria relax, blood pressure becomes higher in ventricles than atria
  • ensures blood flow in pulmonary artery
  • open when pressure in atria higher than in ventricles
  • close when pressure in ventricles is higher than atria
51
Q

What are the semi-lunar valves?

A
  • in aorta and pulmonary artery
  • prevents backflow of blood from aorta/ pulmonary artery into ventricles when blood pressure in the aorta/ pulmonary artery becomes higher than in the ventricles
  • ensures blood flow through aorta and pulmonary artery when their elastic walls recoil to increase pressure within them and ventricles relax reducing the pressure in them
  • open when pressure in ventricles is higher than in arteries
  • close when pressure in arteries is higher than in ventricles

A-Level Biology - Three (3 decks)

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