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A Level Biology > Chapter 8: Transport in Animals > Flashcards

Chapter 8: Transport in Animals Flashcards

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1
Q

Outline similarities between closed + open circulatory systems.

A
  • Liquid transport mediums.
  • Vessels to transport the medium.
  • Pumping mechanism to move the transport fluid around system.
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2
Q

Outline differences between open + closed circulatory system.

A

Open –> few vessels to transport the medium.
Closed –> transport medium (blood) enclosed in vessels.

Open –> transport medium pumped into haemocoel under low pressure.
Closed –> heart pumps blood around body under pressure.

Open –> transport medium comes into direct contact with body cells + tissues.
Closed –> transport medium does not come into contact with body cells.

Open –> transport medium returns to heart through open ended vessel.
Closed –> blood flows relatively fast + returns to heart all within vessels.

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3
Q

Function and structure of elastic fibres (EF)?

A
  • Composed of elastin and can stretch + recoil.

- Provides vessel wall with flexibility.

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4
Q

Function and structure of smooth muscle (SM)?

A
  • Contracts or relaxes altering size of lumen.
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5
Q

Function and structure of collagen (CO)?

A
  • Provides structural support to maintain shape + vol of vessel.
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6
Q

Structure and function of arteries?

A
  • Carry oxygenated blood away from heart.
  • SM + EF + CO
  • Pressure > veins.
  • Walls too thick for diffusion of O2 –> diffusion distance too large.
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7
Q

How do artery walls withstand pressure?

A
  • Wall is thick.
  • Thick layer of collagen to provide strength.
  • Smooth endothelium folded –> no damage to endothelium/artery wall as it stretches.
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8
Q

How do artery walls maintain pressure?

A
  • Thick layer of elastic tissue to cause recoil.

- Thick layers of SM to constrict lumen/artery.

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9
Q

Structure and function of arterioles?

A
  • Carry oxygenated blood away from heart.
  • Link capillaries and arteries.
  • Vasoconstriction + vasodilation.
  • More SM + less EF than arteries.
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10
Q

Explain vasoconstriction.

A
  • SM in arteriole contracts –> constricts lumen/vessel.

- Prevents/reduces blood flowing into capillary bed.

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11
Q

Explain vasodilation.

A
  • SM in arteriole relaxes –> dilates lumen/vessel.

- Allows/increases blood flowing into capillary bed.

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12
Q

Structure and function of capillaries?

A
  • Link arterioles and venules.
  • Blood entering capillaries from arterioles is oxygenated.
  • Blood leaving capillaries for venules is deoxygenated.
  • Thin walls –> short diffusion distance –> where Hb releases O2.
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13
Q

Adaptations of capillaries.

A
  • Large s.a. to vol ratio –> more rapid diffusion.
  • Thin walls –> short diffusion distance.
  • C.S.A of capillaries > arteriole supplying it –> slower rate of blood flow –> more time for exchange of materials by diffusion.
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14
Q

Structure and function of veins?

A
  • Carry deoxygenated blood from body back to heart.
  • Lots of CO + little EF in walls.
  • Valves –> prevent back flow.
  • Thin walls, wide + large lumen/endothelium
  • Pressure < capillaries.
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15
Q

Structure of LARGE veins?

A
  • Wide lumen + smooth lining –> blood flows easily.
  • Thin walls –> don’t have to withstand pressure of arterial system.
  • SM contracts/relaxes –> constriction/dilation –> change amount + pressure of blood.
  • Large lumen –> hold a large vol of blood.
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16
Q

Structure of MEDIUM size veins?

A
  • Wide lumen + smooth lining.
  • Thin walls.
  • Large lumen.
  • SM contracts/relaxes.
  • Valves –> prevent back flow of blood –> ensures it returns to heart.
17
Q

Structure and function of venules?

A
  • Link capillaries with veins.

- Very thin wall with little SM.

18
Q

Adaptations of veins that allow blood to flow under low pressure against force of gravity.

A

One-way valves:

  • Blood flows in direction of heart –> valves stay open.
  • Blood flows backwards –> valves close.

Bigger Veins Run Through Big, Active Muscles in Body:

  • Muscles contract –> squeezing vein to force blood towards heart.

Breathing Movements of Chest Act as Pump:

  • Pressure changes + squeezing actions move blood in veins of chest + abdomen towards heart.
19
Q

How do substances dissolved in blood plasma enter tissue fluid from the capillaries?

A
  1. Diffusion –> from high conc. to low conc. down conc. gradient.
  2. HP in capillaries (arterial end) > tissue fluid
  3. Capillary walls leaky.
  4. Fluid/plasma forced out of capillary from higher pressure to lower pressure.
  5. As fluid/plasma moves out, glucose/O2/small molecules leave with fluid/plasma.
20
Q

Explain the process of carrying O2.

A
  1. When erythrocytes enter capillaries of lungs there is relatively low O2 conc. in cells.
  2. Creates steep conc. gradient between inside of erythrocytes + air in alveoli.
  3. O2 diffuses into erythrocytes + binds to haemoglobin (Hb).
  4. Positive cooperativity arrangement of Hb means that:
    - When one O2 molecule binds to Hb, it changes shape, making it easier for next O2 to bind.
  5. O2 bound to Hb –> free O2 conc. in erythrocytes stays low.
  6. Steep diffusion gradient maintained until all Hb is saturated with O2.
21
Q

Explain the Bohr Shift and why it occurs.

A
  • Reduces affinity of Hb for O2.
  • Formation of haemoglobinic acid –> H+ ions interact with Hb.
  • Hb provides buffering effect –> prevents pH changes.
  • Alter shape of Hb.
  • CO2 binds to Hb forming carbaminohaemoglobin.
  • More O2 released where needed.
22
Q

Why is the fetal Hb curve to the left of the adult Hb curve?

A
  • Placenta has lower pO2.
  • Adult oxyhaemoglobin will release O2 in low pO2.
  • Fetal Hb has higher affinity for O2.
  • More O2 transported around body.
  • Fetal Hb takes up more O2 in lower pO2.
23
Q

Why does blood off load more O2 to actively respiring tissues than resting tissues?

A
  • More O2 released at same pO2.
  • More CO2 produced.
  • Lower affinity of Hb for O2.
  • CO2 produced results in dissociation of carbonic acid.
24
Q

How HCO3 - ions are produced in the erythrocytes.

A
  1. CO2 diffuses into erythrocytes.
  2. CO2 reacts with H2O
  3. Carbonic anhydrase catalyses reversible reaction between CO2 + H2O to form carbonic acid.
  4. Carbonic acid dissociates to form HCO3- and H+ ions.
25
Q

How deoxygenated blood pumped from body to lungs.

A
  1. Enters right atrium through vena cava under relatively low pressure.
  2. Atria –> thin muscular walls.
  3. Blood flows in –> atrio-ventricular valves open –> let blood pass into right ventricle.
  4. Atria contract forcing all blood into right ventricle, stretching ventricle walls.
  5. Ventricle contract –> tricuspid valve closes preventing back flow of blood.
  6. Blood pumped through semilunar valves to pulmonary artery –> pumps blood to capillary blood of lungs.

Summary:

  1. Deoxygenated blood –> vena cava.
  2. Right atrium.
  3. Right ventricle.
  4. Pulmonary artery.
  5. Capillary bed of lungs.
26
Q

How oxygenated blood returns from lungs to body?

A
  1. Enters left atrium from pulmonary vein.
  2. Pressure builds up –> bicuspid valve opens –> atria + ventricles fill with blood.
  3. Atria contract –> forcing all blood into left ventricle.
  4. Ventricles contract –> tricuspid valve closes –> prevent back flow of blood.
  5. Blood pumped through semilunar valves to aorta –> pumps blood all around body.

Summary:

  1. Oxygenated blood –> pulmonary vein.
  2. Left atrium.
  3. Left ventricle.
  4. Aorta.
  5. Pumped all around body.
27
Q

Why is left ventricle thicker?

A
  • Increased force of contraction.
  • Increased pressure.
  • More muscle to create more force.
  • Pump blood against greater resistance.
  • Pump oxygenated blood around body.
  • Prevent damage to capillaries.
  • Right ventricle –> pump deoxygenated blood from body through heart to lungs.
28
Q

What happens in diastole of the cardiac cycle?

A
  • Atria + ventricles relax.
  • Atria then ventricles fill with blood.
  • Vol + pressure increase in heart.
  • Vol + pressure in minimum at arteries.
29
Q

What happens in systole of the cardiac cycle?

A
  • Atria + ventricles contract.
  • Vol + pressure in low in heart but max in arteries.
  • Blood forced out.
30
Q

What is tachycardia?

A
  • Rapid heartbeat.
31
Q

What is bradycardia?

A
  • Slow heartbeat.
32
Q

What is ectopic heartbeat?

A
  • Extra heartbeats that are out of the normal rhythm.
33
Q

What is atrial fibrillation?

A
  • Abnormal heart rhythm.
  • When rapid electrical impulses are generated in atria.
  • Atria contract very fast but not properly.
  • Some impulses passed onto ventricles which don’t contract as much.
  • Blood not pumped efficiently.
34
Q

How does a good blood supply provide efficient gas exchange?

A
  • Maintains steep conc. gradient.

- Removes O2 from lung surface + brings CO2.

35
Q

How does good ventilation provide efficient gas exchange?

A
  • Maintain steep conc. gradient.

- Supplies O2 to alveoli + removes CO2 from alveoli.

36
Q

Explain why oxygen dissociation curve is sigmoidal?

A
  • Co-operative binding of O2 to Hb.
  • First O2 cannot bind easily –> changes shape of Hb.
  • Following oxygens can bind easily.
  • First O2 hardest to remove from oxyhaemoglobin.

A Level Biology (21 decks)

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