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A Level Biology OCR A > 3.1.2 > Flashcards

3.1.2 Flashcards

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1
Q

What is a double circulatory system?

A

One in which the blood flows through the heart twice for each circuit of the body.

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2
Q

What is a single circulatory system?

A

One in which the blood flows through the heart once for each circuit of the body.

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3
Q

What are the main substances transported by the transport system?

A
  • Oxygen
  • Nutrients
  • Hormones
  • Waste
  • Heat
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4
Q

What is the primary need for a transport system in animals?

A

To supply oxygen and nutrients to cells and remove waste products.

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5
Q

Why do very small animals not require a separate transport system?

A

Their cells are surrounded by or very close to the environment, allowing diffusion to supply needs.

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6
Q

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

A
  • Size
  • Surface area to volume ratio
  • Level of metabolic activity
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7
Q

How does size affect the need for a transport system?

A

Larger organisms have cells further from the surface, increasing diffusion distance and reducing rate.

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8
Q

How does surface area to volume ratio affect transport needs?

A

Smaller animals have a larger ratio, allowing sufficient exchange through the body surface.

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9
Q

What is the significance of metabolic activity in the need for a transport system?

A

Higher metabolic activity requires more oxygen and nutrients for energy production.

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10
Q

What are the features of a good transport system?

A
  • A fluid to carry nutrients and wastes (blood)
  • A pump to create pressure (heart)
  • Exchange surfaces (capillaries)
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11
Q

What is pulmonary circulation?

A

The circuit that carries blood to the lungs to pick up oxygen.

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12
Q

What is systemic circulation?

A

The circuit that carries oxygen and nutrients around the body to the tissues.

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13
Q

Which type of circulatory system do fish have?

A

Single circulatory system.

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14
Q

What are the advantages of a double circulatory system?

A
  • Delivers oxygen and nutrients quickly
  • Higher blood pressure increases flow speed
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15
Q

What are arteries?

A

Vessels that carry blood away from the heart.

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16
Q

What are arterioles?

A

Small blood vessels that distribute blood from an artery to the capillaries.

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17
Q

What are capillaries?

A

Very small vessels with very thin walls that allow material exchange.

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18
Q

What is a closed circulatory system?

A

One in which blood is held entirely within vessels.

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19
Q

What is an open circulatory system?

A

One in which blood is not always held within vessels and bathes tissues directly.

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20
Q

What are the disadvantages of open circulatory systems?

A
  • Low blood pressure
  • Slow blood flow
  • Circulation affected by body movements
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21
Q

What are the advantages of closed circulatory systems?

A
  • Higher pressure for faster blood flow
  • Rapid delivery of oxygen and nutrients
  • Independent transport from body movements
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22
Q

What is blood plasma?

A

The fluid portion of the blood containing dissolved substances.

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23
Q

What is tissue fluid?

A

Fluid surrounding cells, formed by plasma leaking from capillaries.

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24
Q

What is lymph?

A

Fluid in the lymphatic system that returns excess tissue fluid to the blood.

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25
What is the role of hydrostatic pressure in fluid movement?
It pushes fluid out of the capillaries into tissues.
26
What are atrioventricular valves?
Valves between the atria and ventricles, ensuring blood flows in the correct direction.
27
What occurs at the arterial end of a capillary?
High hydrostatic pressure pushes fluid out into the tissues.
28
What happens at the venous end of a capillary?
Lower blood pressure allows tissue fluid to return, carrying waste back into the blood.
29
What is the function of venules?
Small vessels that collect blood from capillaries and lead into veins.
30
What are the main components of blood?
* Plasma * Red blood cells * White blood cells * Platelets
31
What is the role of valves in veins?
To help blood flow back to the heart and prevent backflow.
32
What is the function of the heart in the circulatory system?
To pump blood and create pressure for circulation.
33
What is hydrostatic pressure in the context of tissue fluid?
It tends to push fluid into the capillaries ## Footnote Hydrostatic pressure is a key factor in fluid movement across capillary membranes.
34
What does oncotic pressure do in the blood?
It tends to pull water back into the blood ## Footnote Oncotic pressure is primarily due to plasma proteins, which have a negative figure.
35
What is the net effect of hydrostatic and oncotic pressures?
Creates a pressure gradient to push fluid out of the capillary at the arterial end and into the capillary at the venule end.
36
What are atrioventricular valves?
Valves between the atria and the ventricles, which ensure that blood flows in the correct direction.
37
What is cardiac muscle?
Specialised muscle found in the walls of the heart chambers.
38
What is the function of semilunar valves?
Prevent blood re-entering the heart from the arteries.
39
What is the primary role of the mammalian heart?
It is a muscular pump divided into two sides for pumping deoxygenated blood to the lungs and oxygenated blood to the body.
40
Where is the human heart located?
Just off-centre towards the left of the chest cavity.
41
What are the two main pumping chambers of the heart?
The ventricles.
42
What do coronary arteries do?
Supply oxygenated blood to the heart muscle.
43
What can happen if coronary arteries become constricted?
It can reduce the delivery of oxygen and nutrients to the heart muscle, potentially causing angina or a heart attack.
44
What are the four chambers of the mammalian heart?
Two atria and two ventricles.
45
What is the function of the septum in the heart?
Separates the ventricles to ensure oxygenated and deoxygenated blood are kept separate.
46
What is the role of the atrioventricular valves during diastole?
They remain open while the atria contract, allowing blood to flow into the ventricles.
47
What happens during ventricular systole?
The ventricles contract, pushing blood out of the heart.
48
What changes in pressure cause the opening and closing of heart valves?
Changes in blood pressure in the various chambers of the heart.
49
What is bradycardia?
A slow heart rhythm.
50
What is ectopic heartbeat?
An extra beat or an early beat of the ventricles.
51
What does an electrocardiogram (ECG) record?
The electrical activity of the heart.
52
What does fibrillation refer to?
Uncoordinated contraction of the atria and ventricles.
53
What is myogenic muscle?
Muscle that can initiate its own contraction.
54
What is the sinoatrial node (SAN)?
The heart's pacemaker that sends out waves of electrical excitation.
55
What does tachycardia mean?
A rapid heart rhythm.
56
What is the purpose of the wave of excitation generated by the SAN?
To initiate contractions of the heart muscle.
57
What is the role of the atrioventricular node (AVN)?
Conducts the wave of excitation to the ventricles after a delay.
58
What is the function of Purkyne tissue?
Carries the wave of excitation from the AVN down to the ventricles.
59
What does the P wave in an ECG represent?
Excitation of the atria.
60
What does the QRS complex in an ECG indicate?
Excitation of the ventricles.
61
What is the definition of haemoglobin?
The red pigment used to transport oxygen in the blood.
62
What happens when haemoglobin takes up oxygen?
It becomes oxyhaemoglobin.
63
What is affinity in the context of haemoglobin?
A strong attraction for oxygen.
64
What is dissociation in relation to haemoglobin?
Releasing the oxygen from oxyhaemoglobin.
65
What is fetal haemoglobin?
The type of haemoglobin usually found only in the fetus.
66
How does haemoglobin transport oxygen?
Oxygen binds reversibly to haemoglobin in the red blood cells.
67
What is the haemoglobin dissociation curve?
An S-shaped curve that shows how haemoglobin associates with and releases oxygen.
68
What is the significance of the partial pressure of oxygen (pO2)?
It measures the concentration of oxygen in the surrounding tissues.
69
What occurs during the association of oxygen with haemoglobin?
Oxygen binds to haemoglobin in the lungs where pO2 is high.
70
What is the role of blood in oxygen transport?
Carries oxygen from the lungs back to the heart and to the tissues.
71
What facilitates the release of oxygen from oxyhaemoglobin?
The low pO2 in the tissues.
72
What type of curve is produced by the haemoglobin dissociation?
S-shaped curve ## Footnote The S-shaped curve reflects the relationship between oxygen tension and haemoglobin saturation.
73
What happens to haemoglobin at low oxygen tension?
Low saturation level ## Footnote Haemoglobin does not readily associate with oxygen molecules at low oxygen tension.
74
What causes the steepness of the haemoglobin dissociation curve as oxygen tension rises?
Conformational change ## Footnote The change in shape of the haemoglobin molecule allows more oxygen to enter.
75
What is the oxygen tension in the lungs sufficient for?
Close to 100% saturation ## Footnote This ensures efficient oxygen transport from the lungs to the tissues.
76
How does fetal haemoglobin differ from adult haemoglobin?
Higher affinity for oxygen ## Footnote This allows fetal haemoglobin to associate with oxygen in low oxygen tension environments.
77
What is the Bohr effect?
The effect of extra carbon dioxide on haemoglobin, leading to increased oxygen release ## Footnote The Bohr effect explains how increased carbon dioxide concentration facilitates oxygen dissociation.
78
What is carbonic anhydrase?
The enzyme that catalyses the combination of carbon dioxide and water ## Footnote This enzyme plays a crucial role in the formation of carbonic acid from carbon dioxide.
79
What are the three ways carbon dioxide is transported in the blood?
* 5% dissolved in plasma * 10% combined with haemoglobin (carbaminohaemoglobin) * 85% as hydrogencarbonate ions (HCO3-) ## Footnote These methods ensure efficient transport of carbon dioxide from tissues to lungs.
80
What reaction occurs when carbon dioxide diffuses into red blood cells?
CO2 + H2O -> H2CO3 ## Footnote This reaction forms carbonic acid, which subsequently dissociates.
81
What is the chloride shift?
Movement of chloride ions into erythrocytes to balance charge as hydrogencarbonate ions leave ## Footnote This process maintains the electrical neutrality of red blood cells.
82
What is haemoglobinic acid?
The compound formed by the buffering action of haemoglobin with excess hydrogen ions ## Footnote Haemoglobin acts as a buffer to maintain pH levels.
83
What happens to haemoglobin when carbon dioxide concentration increases?
Haemoglobin releases more oxygen ## Footnote Increased carbon dioxide leads to increased hydrogen ions, reducing haemoglobin's affinity for oxygen.
84
True or False: The Bohr effect results in more oxygen being released where more carbon dioxide is produced.
True ## Footnote The Bohr effect aids in oxygen delivery to metabolically active tissues.
85
Fill in the blank: The _______ describes the downward and rightward shift of the haemoglobin dissociation curve due to increased carbon dioxide.
Bohr shift ## Footnote This shift reflects the physiological adaptation of haemoglobin to varying metabolic conditions.

A Level Biology OCR A (3 decks)

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