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Biology Paper 1 > 3.3.4.1 - Mass transport in animals > Flashcards

3.3.4.1 - Mass transport in animals Flashcards

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1
Q

How does the structure of red blood cells link to their function?

A
  1. biconcave disc - high SA:V ratio
  2. No nucleus or organelles - contains only haemoglobin which improves the oxygen carrying capacity
  3. Flexible - allows oxygen to pass through narrow capillaries
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2
Q

Describe the primary structure of haemoglobin

A

two alpha and two beta polypeptide chains

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3
Q

Describe the secondary structure of haemoglobin

A

each polypeptide chain is coiled into a helix

Hydrogen bonds

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4
Q

Describe the tertiary structure of haemoglobin

A

each polypeptide chain is folded into a precise shape

Hydrogen, ionic and disulphide bonds

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5
Q

Describe the quaternary structure of haemoglobin

A
  • all four polypeptides are linked to form a spherical shape
  • each polypeptide chain is associated with a haem group
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6
Q

How does the structure of haemoglobin help overcome the lack of solubility in oxygen?

A
  • hydrophillic R groups face out, which maintains solubility
  • this allows oxygen to be transported effectively once it binds to the iron containing haem group
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7
Q

Define affinity

A

attraction between molecules that results in the formation of a new molecule

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8
Q

Define partial pressure

A

measure of oxygen concentration in cells

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9
Q

Define association

A

process by which haemoglobin binds with oxygen

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10
Q

Define dissociation

A

process by which haemoglobin releases its oxygen

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11
Q

How does the affinity of haemoglobin change based on the environment?

A
  • Site of gas exchange (alveoli) - high partial pressure of oxygen so haemoglobin has a **high oxygen affinity and readily associates **
  • Site of respiration - low partial pressure of oxygen so haemoglobin has a low oxygen affinity and readily dissociates
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12
Q

What two factors affect the type of haemoglobin present in an organism?

A
  1. high altitude - increased affinity for oxygen (oxygen loads more readily as there is a limited supply)
  2. high metabolic rate - decreased affinity for oxygen (oxygen unloads more readily for respiration)
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13
Q

Describe the trend of an oxygen dissociation curve in humans?

A
  • curve is initially shallow - at low partial pressure little oxygen binds to the haemoglobin (due to the shape it is difficult for the first molecule to bind)
  • gradient on the curve** steepens** - once the first oxygen molecule has bound, the quaternary structure changes which changes the haemoglobin shape - this induces other subunit to bind
  • (POSITIVE COOPERATIVITY) - it takes a smaller increase in partial pressure to bind the second oxygen
  • graph plateaus - majority of binding sites are now occupied (3/4) so there is a** lower probability of an oxygen molecule bonding to an empty haem group**
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14
Q

What does a steep increase mean on an oxygen dissociation curve?

A

enables a large change in the haemoglobin saturation with a small change in oxygen partial pressure

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15
Q

What doe the Bohr shift show?

A

movement of the oxygen dissociation curve to the right due to increased carbon dioxide levels
(when the partial pressure of carbon dioxide is high, haemoglobins affinity for oxygen is reduced)

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16
Q

Describe the effects of increasing carbon dioxide on oxyhaemoglobin dissociation

A
  • highly respiring tissues produce a lot of carbon dioxide
  • this decreases the affinity of haemoglobin for oxygen (as there is a lower oxygen partial pressure)
  • so there is increased unloading of oxygen at respiring tissues
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17
Q

Describe the Bohr shift in respiring tissues

A
  • ** carbon dioxide concentration increases *and dissolves in the blood plasma
  • carbon dioxide forms carbonic acid
  • increase in the H+ ion concentration so pH of blood plasma decreases
  • oxygen affinity of haemoglobin is reduced so oxygen is more readily dissociated *
  • MORE oxygen is available for respiration at the same partial pressure
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18
Q

Describe the Bohr shift in gas exchange surfaces such as the alveoli

A
  • Bohr effect is reversed
  • concentration of carbon dioxide is lower
  • haemoglobin has a higher affinity for oxygen (due to the increased pH)
  • oxygen associates more readily
  • more oxygen is taken in at the same partial pressure
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19
Q

How does the oxyhaemoglobin dissociation curve for a lugworm compare to a human?

A
  • curve is** shifted to the left**
  • lugworms live in burrows and when the tide goes out burrow contains progressively less oxygen (low partial pressure) - depleted oxygen environment
  • difficult for oxygen association to occur
  • so the lugworm haemoglobin has a HIGHER affinity for oxygen (so it if fully loaded even when there is minimal in the environment)
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20
Q

How does the oxyhaemoglobin curve of the Llama compare to a human?

A
  • Curve is shifted to the left
  • ** High altitude **so partial pressure of oxygen is low
  • difficult for oxygen association to occur
  • haemoglobin has a higher affinity for oxygen
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21
Q

How does the oxyhaemoglobin curve of a bird or small mammal compare to a human?

A
  • curve is shifted to the right
  • high metabolic rate - high oxygen demand
  • so haemoglobin has a lower affinity for oxygen
  • so oxygen dissociates more readily for use in respiration
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22
Q

Define saturation

A

when all the oxygen binding sites are taken up (so haemoglobin contains four oxygen molecules)

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23
Q

What two factors determine whether an organism will have a specialised transport system or pump?

A

They need a pump if…
1. high metabolic rate
2. small surface area to volume ratio - greater need for a pump as substances need to travel further

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24
Q

Why is it important that mammals have a closed, double circulatory system?

A

allows pressure to be increased and decreased depending on where in the body blood is going
** lungs - blood pressure is reduced** but if this passed to the rest of the body circulation would be very slow
* Heart - **pressure is increased **before being circulated to the rest of the tissues - allows substances to be delivered quickly which is important as mammals have a high temp and rate of metabolism

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25
Q

Give the four main features of an effective transport system
-why are they important?

A
  • **medium such as water **to carry materials - also a mechanism to move the transport medium (eg a pressure difference)
  • ** closed system of vessels*** which form a branching network to reach all tissues
  • movement mechanism (either muscle contraction or passive process like evaporation of water in plants)
  • valves to maintain unidirectional flow
    *
26
Q

Function of the vena cava

A

connected to the **right atrium **and delivers deoxygenated blood from the tissues in the body

27
Q

;

Function of the pulmonary artery

A

connected to the **right ventricle **and carries deoxygenated blood to the lungs to be replenished with oxygen

28
Q

Function of the aorta

A

largest blood vessel in the body and carries oxygenated blood away from the left ventricle to all parts of the body (apart from the lungs)

29
Q

Function of the pulmonary vein

A

connected to the** left atrium** and delivers oxygenated blood from the lungs ready to be pumped around the body

30
Q

Define atrium

A

thin walled and elastic so it can stretch as it collects blood

31
Q

Define ventricle

A

thick muscular wall as it has to contract strongly to pump blood to the lungs or body

32
Q

Why does the heart have two separate pumps?

A
  • blood to the lungs is very low pressure (due to tiny capillaries) - blood flow to the rest of the body would be very slow
  • blood is returned to the heart so** pressure can be increased **before distribution to the rest of the body
33
Q

The muscular walls of the** ventricles are much thicker than the wall of the atria **- why is this?

A
  • blood from the ventricles is pumped a much greater distance than from the atria
  • so thick walls allow the ventricles to **contract **with more force
  • so they can generate a high enough** pressure** to pump blood to the lungs or body
34
Q

The wall of the left ventricle is thicker than that of the right ventricle - why is this?

A
  • left ventricle has to pump blood to the entire body
  • so the ventricle wall is thicker as it needs to contract with more **force **
  • to generate a high enough** pressure**
35
Q

Function of the atrioventricular valves

A
  • separate the atria from the ventricles - as pressure in the ventricles is increased this prevents the valves opening
  • Right atrioventricular valve (Tricuspid) - three cup shaped flaps
  • Left atrioventricular valve (Bicuspid) - two cup shaped flaps
36
Q

Define myocardial infarction

A
  • heart attack
  • arteries become blocked which limits the blood and oxygen which can reach the heart muscle
  • muscles in this area can’t respire anaerobically so die
37
Q

Define systole

A

contraction of the heart and emptying of chambers

38
Q

Define diastole

A

relaxation of the heart and filling of chambers

39
Q

Describe what happens during diastole

A

* RELAXATION OF THE HEART - both the atria and the ventricles are relaxed
**atria passively fill with blood **(via pulmonary vein and vena cava) and the pressure rises.

40
Q

Describe what happens during** atrial systole**

A
  • ATRIA CONTRACT
  • pressure in atria is greater than in the ventricles so the atrioventricular valves open
  • remaining blood is forced into the ventricles
  • ventricles remain RELAXED during this phase
41
Q

Describe what happens during ventricular systole

A
  • CONTRACTION OF THE VENTRICLES
  • once ventricles have been filled with blood they contract together
  • Pressure is HIGHER in ventricles than atria so atrioventricular valve closes (prevents backflow of blood into atria
  • Pressure in ventricles rises further till it is HIGHER than aorta and pulmonary artery so semi-lunar valve opens and blood flows into these vessels - once blood has flowed the semi-lunar valve will close again
42
Q

Describe the role of the atrioventricular valves

A

prevent backflow of blood (into atria) when ventricle pressure is greater than atrial pressure - means blood flows into the aorta and pulmonary artery

43
Q

Describe the role of semi-lunar valves

A
  • within the aorta and pulmonary artery
  • prevents backflow of blood into the ventricles when pressure in these vessels rises
44
Q

Describe the role of pocket valves

A
  • in veins
  • ensures blood flows back to the heart when veins are squeezed
45
Q

How does the shape of blood valves impact whether blood passes through?

A
  • cusp shaped flaps
  • if blood gathers on the convex side flaps open to let blood pass
  • if blood gathers on the concave side, cusps are pushed together which prevents blood passing through
46
Q

What is cardiac output and how is it measured?

A

Cardiac output = volume of blood pumped by one ventricle of the heart in one minute
Cardiac output (dm^3 min -1) = heart rate x stroke volume

Heart rate = rate at which the heart beats
Stroke volume = volume of blood pumped out at each beat

47
Q

How does ventricular pressure change during the cardiac cycle?

A

1.** atrial systole**
- initially low but gradually increases as the atria contract and fill ventricles with blood (Passive filling)
2. ventricular systole
-** atrioventricular valve closes and PRESSURE rises rapidly as ventricles contract**
- pressure rises above aorta so blood flows out via semi-lunar valve
3. *.** diastole (relaxation)**
- Semi-lunar valve closes and PRESSURE FALLS as ventricles empty
- **atrioventricular valve opens **again so pressure in the ventricles rises againas blood flows in

48
Q

How does atrial pressure change during the cardiac cycle?

always tends to be quite low as thin atrium walls cannot create much force

A
  1. atrial systole
    - HIGHEST PRESSURE due to contraction
  2. ventricular systole
    - atrioventricular valve closes and atria walls relax so PRESSURE DROPS
  3. diastole
    - atria fill with blood which results in HIGHER PRESSURE
    - SLIGHT PRESSURE DECREASES as left* atrioventricular valve opens** and some passively blood moves into the ventricles
    - PRESSURE INCREASE as atria continue to fill
49
Q

How does aortic pressure change during the cardiac cycle?

A
  1. atrial systole
    - PRESSURE is low as **semi lunar valve is closed **
  2. ventricular systole
    - semi lunar valve opens so PRESSURE RISES rapidly as blood flows into aorta
  3. diastole
    -** atrioventricular valve closes **so PRESSURE DECREASES as blood is not flowing into aorta
50
Q

How does ventricular volume change during the cardiac cycle?

A
  1. atrial systole
    - VOLUME increases as ventricles stretch while filling
  2. ventricular systole
    - VOLUME decreases as ventricles are contracting which reduced the volume of the chamber
  3. diastole
    - VOLUME increases as ventricles expand as they relax and fill with blood
51
Q

How does atrial volume change during the cardiac cycle?

A
  1. atrial systole
    - VOLUME decreases due to atrial contraction
  2. ventricular systole
    -VOLUME increases as atria expand and fill with blood
  3. diastole
    - VOLUME decreases slightly as some blood passively moves from atria to ventricle when AV valve opens
52
Q

Describe coronary heart disease

A
  • deposits of fatty material build in coronary artery which build up to form an atheroma (fibrous plaque)
  • lumen shrinks which make it more difficult for blood to pass through and increases blood pressure - can lead to a heart attack
53
Q

Define aneurysm
Define thrombosis

A

Aneurysm - balloon-like swelling in the arteries (caused by weakened arteries and high blood pressure)
Thrombosis - formation of a blood clot (causes by platelets and fibrin accumulating at the damaged artery surface) which can caused a blockage in the artery

54
Q

Give the three main risk factors for cardiovascular disease

A
  1. high blood pressure and poor diet - cholesterol = atheromas which can cause blood clots and block blood to the heart
  2. smoking = increases blood pressure and reduces oxygen available to tissues
  3. high blood pressure = increases risk of damage to the artery walls which means increased risk of atheromas
55
Q

What is the function and structure of arteries?

A

carry high pressure blood AWAY from the heart and into arterioles
* thick muscle layer - allows arteries to constrict to control the volume of blood passing through
* thick elastic layer - keeps blood at a high pressure
* thick wall - prevents vessel bursting under high pressure
* no valves - already at high pressure so doesn’t tend to flow backwards

56
Q

What is the function and structure of arterioles ?
How does the structure compare to arteries ?

A

carry blood from arteries to capillaries
* THICKER muscle layer than arteries - allows blood flow into the capillaries to be controlled
* THINNER elastic layer - lower blood pressure

57
Q

What is the function and structure of the veins ?

A

carry low pressure blood from capillaries in tissues to the heart
* thin muscle layer - carrying blood away from tissues so don’t need to constrict/dilate
* thin elastic layer - low pressure so veins will not burst
* thin wall - low pressure - also allows veins to be flattened easily to pressurise blood
* valves - ensures pressurised blood doesn’t flow backwards

58
Q

What is the function and structure of capillaries ?

A

exchange metabolic materials between cells and blood
* very thin - short diffusion path
* numerous and highly branched - large surface area for diffusion
* narrow diameter - permeate tissues to provide a short diffusion path
* narrow lumen - red blood cells are pushed against them which reduces diffusion distance to cells
*

59
Q

Define tissue fluid - why is it useful ?

A

fluid which surrounds cells in tissues - made from small molecules (oxygen, water, nutrients) which have left the blood plasma
- cells take in oxygen and nutrients and release metabolic waste

60
Q

How is tissue fluid formed?

A
  1. **Arterial end **of capillary bed- hydrostatic pressure in capillaries is greater than in tissue fluid - due to pumping of the heart
  2. fluid is forced out of capillaries into spaces around the cells - forms tissue fluid
    - all red blood cells and and most proteins remain in the blood as they are too large to cross the membrane
61
Q

How is tissue fluid returned ?

A
  1. tissue fluid exchanges materials with cells
  2. **hydrostatic pressure reduces in the capillaries as fluid leaves **- lower at venule end
  3. hydrostatic pressure at venule end is lower than surrounding tissue fluid (due to fluid loss and increased concentration of plasma proteins - lower water potential)
  4. so** tissue fluid re-enters capillaries via osmosis** down the water potential gradient
  5. excess tissue is drained into the lympatic system - transports excess fluid back into circulatory system
62
Q

How are the contents of the lymphatic system moved?

A
  • hydrostatic pressure of tissue fluid that has left the capillaries
  • contraction of body muscles

Biology Paper 1 (15 decks)

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