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Biology: Unit 3 > 3.2: Transport in animals > Flashcards

3.2: Transport in animals Flashcards

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1
Q

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

A

Size:
Cells inside a large organism are further from its surface
The diffusion pathway is increased - diffusion rate is reduced - too slow to supply all the requirements

Surface area to volume ratio
Small organism - sufficient area of body surface where exchange can occur
Large organism - smaller area of body surface

Level of metabolic activity
Animals that are very active need good supplies of oxygen (for respiration - food) and nutrients in cells to supply the energy for movement

  • Animals that keep themselves warm need energy
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2
Q

What are features of a good transport system?

A
  • Fluid or medium to carry oxygen, water and nutrients around the body - blood
  • A pump to create pressure and push the fluid around the body - heart
  • Exchange system enable substances to enter and leave the blood - Capillaries
  • Tube of vessels to carry the blood by mass flow
  • Two circuits - one to pick up oxygen and another to deliver it to the tissues
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3
Q

What is a single circulatory system?

A

Blood flows through the heart once for each circuit of the body
Heart -> gills -> body -> heart ->
Blood has low pressure (as it flows towards the body) and it doesn’t flow quickly

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4
Q

What is a double circulatory system?

A

Two separate circuits

  • Pulmonary circulation - blood to lungs to pick up oxygen + low pressure as it may damage capillaries in lungs
  • Systemic circulation - oxygen and nutrients around the body to tissues + blood can be made to flow more quickly by increasing blood pressure in the heart
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5
Q

What is an open circulatory system?

A

Blood fluid circulates through the body cavity - not always held within blood vessels

  • Blood pressure is low and blood flow is slow
  • Circulation of blood may be affected by body movements or lack of
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6
Q

What is a closed circulatory system?

A

Blood stays entirely inside vessels, tissue fluid bathes the tissues + cells

  • Higher pressure - blood flows more quickly
  • More rapid delivery of oxygen and nutrients
  • More rapid removal of carbon dioxide and other wastes
  • Transport is independent of body movements
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7
Q

What are arteries?

A

Blood vessels that carry blood away from the heart
Adapted to carry blood at high pressure

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8
Q

What are arterioles and their structure?

A

Carry blood from arteries into capillaries

  • Smaller that arteries
  • Larger lumen
  • Walls have more smooth muscle and less elastin as they do not need to withstand high pressure
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9
Q

What are capillaries?

A

Site of diffusion between blood and body tissues
Form extensive network between arterioles and venules

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10
Q

What are venules and their structure?

A

Carry blood from capillaries into veins

  • Smaller than veins
  • They have very thin walls
  • Very little smooth muscle
  • Has valves
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11
Q

What are veins?

A

Blood vessels that return blood to the heart
Adapted to carry at low pressure

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12
Q

What are adaptations of arteries?

A
  • Collagen - provides strength to prevent the vessel form bursting and to maintain vessel shape
  • Elastic fibres - contain elastin that lets them stretch and recoil to minimise changes in pressure
  • Thick smooth muscle layer - contracts/relaxes to constrict/dilate the lumen and control blood flow
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13
Q

What controls blood flow in the arteries and how does it do it?

A

Smooth muscle
Does this by vasoconstriction and vasodilation

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14
Q

What is vasoconstriction?

A

Smooth muscle contracts, constricting the blood vessel and decreasing blood flow

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15
Q

What is vasodilation?

A

Smooth muscle relaxes, dilating the blood vessel and increasing blood flow

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16
Q

What are adaptations of capillaries?

A
  • Lumen is very narrow - allows red blood cell to be close to body cells
  • Wall are thin - substances can be exchanged across a short diffusion distance by diffusion
  • Highly branched - this provides a large surface area for diffusion
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17
Q

What are adaptations of veins?

A
  • Collagen - provides strength to prevent the vessel from bursting and maintain vessel shape
  • Little smooth msucle and elastic fibre - not much is needed due to low blood presssure and thinner walls allow veins to be easily compressed, aiding the flow of blood
  • Valves - pocket valves shut to prevent the backflow of blood when veins are squeezed by surrounding skeletal msucle tissues
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18
Q

What does blood consist of?

A
  • Plasma - mostly water, transports substances in solution
  • Red blood cell - carry oxygen
  • White blood cell - immune cells
  • Platelets - involved in clotting
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19
Q

What are the functions of blood?

5x

A
  • Transports O2 and CO2
  • Transports nutrients from digestion
  • Transports waste for excretion
  • Transports hormone
  • Transports food from storage
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20
Q

What is tissue fluid?

A

Fluid where cells are soaked in to facilitate substance exchange between cells and blood

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21
Q

What is tissue fluid not made out of?

A
  • No red blood cell
  • Fewer white blood cellss
  • Fewer proteins
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22
Q

How is the formation of tissue fluid determined?

A

It is determined by the filtration pressure which is determined by osmotic and hydrostatic pressure

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23
Q

What is osmotic pressure?

A

Tendancy of H2O moving into blood by osmosis
Generated by plasma proteins that decrease water potential in the blood
Always -3.3kPa

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24
Q

What is hydrostatic pressure?

A

Pressure generated by heart contraction
Changes due to location:

  • Arteriol = +4.6kPa
  • Venous = +2.3kPa
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25
Q

What is…

  • Negative pressure
  • Positive pressure
A
  • Move into blood (plasma proteins never leave bloodstream - too big)
  • Move out of blood
26
Q

What happens at the arteriole end of the capillaries?

A
  1. A high hydrostatic pressure, exerted by the force of the heart pumping, forces fluid out of capillaries
  2. This forms tissue fluid surrounding body cells
27
Q

What happens at the venule end of capillaries?

A
  1. The hydrostatic pressure is lower
  2. The proteins in blood exert a high oncotic pressue in capillaries
  3. The water potential is lower in capillaries than in tissue fluid due to fluid loss
  4. Some tissue fluid moves back into capillaries by osmosis
28
Q

What is lymph and what is it made up of?

A

Fluid that flows around the lymphatic system via lymph vessels

  • Less oxygen and nutrients
  • More fatty acids
  • More white blood cells
29
Q

What is the steps of formation and transport of lymph?

5 steps

A
  1. Some tissue fluid doesn’t re-enter capillaries from tissue fluid
  2. This fluid instead drains into lymph vessels forming lymph
  3. Lymph is transported through the lymph vessels by muscle contractions
  4. Lymph is passed through lymph nodes to filter pathogens
  5. Lymph is eventually returned to the blood
30
Q

What is haemoglobin?

A

Large globular conjugated protein

31
Q

What are features of haemoglobin?

A
  • Bound to an inorganic group (haem group)
  • 4 subunits (2 alpha and 2 beta)
  • Each subunit has one haem group (each binds to one oxygen molecule)
  • 300 million Hb per rbc
  • Shows positive cooperativity
32
Q

What is positive cooperativity?

A

Binding of one oxygen molecule changes the Hb shape (conformational change allows subunit to bind to O2 easier)
Increases Hb’s affinity for oxygen
When haemoglobin is mostly saturated with oxygen, it is harder for more oxygen to bind

33
Q

What happens to oxygen and haemoglobin?

A
  1. Red blood cells contain haemoglobin which have haem groups
  2. In the capillaries in the lungs, oxygen binds to iron ions haem groups forming oxyhaemoglobin
  3. Each haemoglobin molecule can carry 4 oxygen molecules
  4. Oxyhaemoglobin can be transported via blood to respiring body tissues
  5. At body cells, oxygen dissociates from haemoglobin
34
Q

What are factors affecting haemoglobin saturation?

A

Oxygen concentration or partial pressue of oxygen (pO2)

35
Q

What does a higher and lower partial pressure of oxygen do to haemoglobin saturation?

A
  • Higher pO2 - haemoglobin has a high affinity and binds with it (e.g in the lungs)
  • Lower pO2 - haemoglobin has a low affinity for oxygen and releases it (e.g at respiring body cells)
36
Q

What are differences between fetal and aduly haemoglobin?

A

Fetal haemoglobin - found in the rbc of an unborn fetus

  • Fetus needs to obtain oxygen from the mother’s blood
  • The fetal haemoglobin therefore has a higher oxygen affinity than the adult haemoglobin found in the mother’s blood
  • Oxygen dissociates from the mother’s haemoglobin and bind with Hb in fetal blood
  • Ensures the fetus gets enough oxygen to surivive while it develops
37
Q

What is the Bohr effect?

A

Haemoglobin has lowe affinity for O2 at higher partial pressure for carbon dioxide (pCO2)

  • Shifts oxygen dissociation curve to the right
38
Q

How does partial pressure of carbon dioxide affect haemoglobin saturation?

A

Higher pCO2 at respiring tissues causes haemoglobin to release oxygen
This means the oxygen saturation of haemoglobin is lower for a given pO2

39
Q

What are the three ways CO2 is transported via the blood?

A
  1. A small percentage of CO2 is trnasported dissolved in plasma
  2. Some CO2 enters rbc and is transported bound to haemoglobin as carbominohaemoglobin
  3. Most CO2 enters the rbc and undergoes a reaction in the cytoplasm to form hydrogen carbonate ions
40
Q

Why is it beneficial for CO2 to be converted into another form in the blood?

A

Maintains a steep diffusion gradient between respiring tissues, need to get rid of CO2, and the blood which removes CO2 to the lungs

41
Q

How is CO2 transported a respiring tissues which have a high pO2?

A
  1. CO2 reacts with water to form carbonic acid (H2CO3) - catalysed by the enzyme carbonic anhydrase
  2. H2CO3 dissociates to H+ and HCO3- (hydrogen carbonate ions)
  3. H+ binds to haemoglobin forming hamoglobonic acid - releases O2
  4. This prevents the blood from becoming too acidic (H+ ions reduce pH)
  5. It also causes the Bohr effect
  6. HCO3- ions leave the rbc and are transported via plasma while chloride ions enter rbc
  7. This is called the chloride shift
42
Q

How is CO2 transported at lungs which have a low pO2?

A
  1. The low pCO2 causes HCO3- and H+ to reform CO2
  2. CO2 diffuses out of the body during expiration
43
Q

What type of blood does the left side of the heart and right side of the heart carry?

A

Left = oxygenated blood
Right - deoxygenated blood
Forms two separate pumping mechanisms

44
Q

Why does the heart have two separate pumping mechanisms?

A
  • Blood pressure drops in the lungs as it flows through the capillaries
  • A single pump would slow the blood flow to the body cells
  • Two pumps increase the pressure before the blood circulates
45
Q

What does the septum do?

A

Separates the two sides of the heart, preventing the mixture of deoxygenated and oxygenated blood

46
Q

What is the structure and function of atrioventricular valves?

A
  • Tricuspid valve - located between right atrium and right ventricle
  • The bicuspid valve - located between left atrium and left ventricle
  • Both valves prevent backflow of blood onto the atria when the ventricles contract
47
Q

What is the structure and function of the semilunar valves?

A
  • These are located between the ventricles and the pulmonary artery and aorta
  • Prevent the backflow of blood into the ventricles when they relax
48
Q

What are the four blood vessels that separate the heart chambers?

A

Pulmonary vein
Aorta
Vena carva
Pulmonary artery

49
Q

What is the role of the pulmonary vein?

A

Moves oxygenated blood into the left atrium from the lungs

50
Q

What is the function of the aorta?

A

Moves oxygenated blood from the left ventricle to the body

51
Q

What is the role of the vena carva?

A

Moves deoxygenated blood into the right atrium from the body

52
Q

What is the role of the pulmonary artery?

A

Moves deoxygenated blood from the right ventricle to the lungs

53
Q

Why do ventricles have thicker walls with more muscle than the atria?

A
  • Atria only need enough pressure to pump blood a short distance into the ventricles
  • The ventricles need a lot of pressure to pump blood a long distance out of the heart to other organs
54
Q

Why does the left ventricle have thicker walls with more muscle than the right ventricle wall?

A
  • Right ventricle only needs enough pressure to pump deoxygenated blood a short distance to the lungs
  • Left ventricle needs a lot of pressure to pump oxygenated blood to the other more distant organs of the body
55
Q

What is stage one of the cardiac cycle?

A

Atrial systole

  1. The ventricles relax and the atria contract
  2. This increases the atrial pressure
  3. The atrioventricular valves open
  4. Blood flows inot ventricles
56
Q

What is the third stage of the cardiac cycle?

A
  1. The ventricles and atria relax
  2. The semi lunar valves close
  3. Blood flows passively into the atria
57
Q

What is stage 2 of the cardiac cycle?

A

Ventricular systole

  1. The ventricles contract and the atria relax
  2. The ventricular pressure increases
  3. The semi-lunar valves open and the atrioventricular valves close
  4. Blood flows into the arteries
58
Q

What is cardiac output and how is it measured?

A

Volume of blood pumped by one ventricle of the heart in one muscle
Heart rate x stroke volume (volume of blood that is pumped out of the left ventricle during ventricular systole)

59
Q

Cardiac cycle is myoygenic so how does the wave of electrical excitation travel?

A
  1. SAN - initiates the heartbeat by stimulating the atria to contract. A layer of collagen fibres prevents direct electrical flow from the atria to the ventricles
  2. AVN - picks up electrical activity form the SAN and imposes a slight delay
  3. Bundle of His - recieves electrical activity and conducts the wave of excitation to the heart’s apex
  4. Purkyne fibres - branch off the bundle of His, causing the right and left ventricle to contract from the bottom upwards
60
Q

What stages of the cardiac cycle do ECGs show?

A

P wave - atrial systole
QRS - ventricular systole
T wave - diastole

61
Q

What are the abnormalities that ECGs help diagnose?

A
  • Tachycardia - abnormally rapid heart rate
  • Bradycardia - abnormally slow heart rate
  • Ectopic heartbeats - heartbeats out of the normal rhythm
  • Atrial fibrilation - abnormally rapid and ineffective contraction of the atria

Biology: Unit 3 (3 decks)

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