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Biology > Surface Area to Volume Ratio and Gas Exchange > Flashcards

Surface Area to Volume Ratio and Gas Exchange Flashcards

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1
Q

What is the need for specialised exchange surfaces?

A

As the size or an organism and it’s surface area to volume ratio increases.

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2
Q

What are the main features of an efficient exchange surface?

A
  • Large surface area
  • Short diffusion distance
  • Good blood supply/ventilation
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3
Q

What are the main features of Fish exchange system?

A
  • Four pairs of gills, each supported by an arch
  • Along each arch are gill filaments
  • Gill filaments lined with lamellae
  • Projections held apart by water flow = stick together out of water = fish can’t breathe
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4
Q

What is meant by counter current flow?

A
  • Blood and water flow in opposite directions
  • Ensures a steep diffusion gradient maintained
  • Maximum amount of oxygen is diffusing into deoxygenated blood from the water
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5
Q

How does ventilation occur in fish?

A
  • Continuous unidirectional flow
  • Fish opens mouth = lowering the floor of buccal cavity
  • Allows water to flow in
  • Fish closes mouth = raising buccal cavity floor, increasing the pressure.
  • Water is forced over gill filaments by the difference in pressure.
  • Operculum acts as a valve and pump.
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6
Q

What are the main features of terrestrial insects gas exchange systems?

A
  • Spiracles = small openings covering insects body
  • Trachea and Tracheoles
  • Cellular fluid
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7
Q

How does the terrestrial insect gas exchange system work?

A
  • Gases move in and out through diffusion, mass transport as a result of muscle contraction and as a result of volume changes in the trachea.
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8
Q

What is the plant gas exchange system?

A
  • Leaves have many small holes called stomata
  • Large number of stomata of these = no cell is far from the stomata, reducing the diffusion distance.
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9
Q

What is the structure of mammalian lungs?

A
  • Pair of lobed structures with large surface are located in the chest cavity, that are able to inflate.
  • Surrounded by a ribcage to protect them.
  • External and internal intercostal muscles between ribs contract and relax to raise and lower the ribcage.
  • Diaphragm.
  • Trachea, bronchi, and bronchioles.
  • Alveoli = gas exchange occurs.
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10
Q

How is the airway held open?

A
  • Rings of cartilage, incomplete in the trachea to allow passage of for food down the oesophagus behind the trachea.
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11
Q

What is loose tissue?

A

The inside surface of cartilage is a layer of glandular and connective tissue, elastic fibres, smooth muscle and blood vessels.

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12
Q

How are alveoli adapted for gas exchange?

A
  • Very thin (one cell thick), surrounded by one cell thick capillaries = short diffusion pathway
  • Constant blood supply by capillaries = step concentration gradient maintained
  • Large number of alveoli = large collective surface area
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13
Q

What is the function of the Goblet cells?

A
  • Present in the trachea, bronchi and bronchioles involved in mucus secretion, to trap bacteria and dust = reduces risk of infection.
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14
Q

What is the function of the Ciliated Epithelium?

A
  • Present in bronchi, bronchioles and trachea, involved in moving mucus along to prevent lung infection, by moving it toward the throat to be swallowed.
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15
Q

What is the function of smooth muscle?

A
  • Ability to contract enables them to play a role in constricting the airway, controlling the flow of air to and from the alveoli.
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16
Q

What is the function of Elastic fibres?

A
  • Stretch when we exhale and recoil when we inhale thus controlling the flow of air.
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17
Q

What is the process of inspiration?

A
  • External intercostal muscles contract
  • Internal intercostal muscles relax
  • Diaphragm contracts and flatterns
  • Increases the volume inside the thorax, lowering the pressure
  • Difference in pressure creates a gradient and causes air to be forced into the lungs.
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18
Q

What is the process of expiration?

A
  • Internal intercostal muscles contract
  • External intercostal muscles relax
  • Diaphragm relaxes and returns to domes shape
  • Decreasing the volume inside the thorax, increasing pressure forcing air out of the lungs.
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19
Q

What is a Spirometer?

A
  • A device used to measure lung volume
  • A person breathe in and out of the air tight chamber, causing it to move up and down, leaving a trace on a graph
20
Q

What is vital capacity?

A

The maximum volume of air that can be inhaled or exhaled in a single breath
- depends on gender, age, size and height

21
Q

What is tidal volume?

A

The volume of air we breathe in and out at each breath at rest

22
Q

What is breathing rate?

A

The number of breaths per minute, can be calculated from the spirometer trace by counting the number of peaks or troughs per minute

23
Q

What is digestion?

A

The hydrolysis of large biological molecules into smaller molecules which can be absorbed across cell membranes

24
Q

How are carbohydrates broken down?

A
  • Amylase in the mouth = large polymers
  • Maltase in the ileum break down monosaccharides
  • Sucrase and lactase break down the disaccharides sucrose and lactose
25
Q

How are lipids broken down?

A
  • Lipases hydrolyse ester bonds between the monoglycerides and fatty acids
  • Emulsified into micelles by bile salts released by the liver
  • Increases the surface area for enzymes to act on
26
Q

How are proteins broken down?
(Three types of enzyme?)

A
  • Endopeptidases = hydrolyse peptide bonds between amino acids in the middle of a polypeptide
  • Exopeptidases = hydrolyse bonds at the end of polypeptides
  • Dipeptidases = hydrolyse dipeptides into individual amino acids.
27
Q

How are amino acids absorbed in mammals?

A
  • Absorbed in the ileum
  • Amino acids by facilitated diffusion, in epithelial cells
  • With each amino acid a Na+ is also taken up through co-transport.
  • Diffusion gradient for Na+ is maintained by active transport through the epithelial cells.
28
Q

How are monoglycerides and fatty acids absorbed in mammals?

A
  • They are polar so they can easily diffuse across the cell membrane into the epithelial cells.
  • They are then transported to the endoplasmic reticulum, where they are made into triglycerides again.
  • Then they move out of the cells by vesicles into the lymph system.
29
Q

What is Haemoglobin?

A
  • A water soluble globular protein, which consists of two beta polypeptide chains and two alpha helices.
  • Each molecule contains a haem group.
  • Carries oxygen in the blood, oxygen binds to the haem group.
    Each molecule can carry four oxygen molecules.
30
Q

What is affinity of oxygen and how does it vary?

A
  • Varies depending on the partial pressure of oxygen which is a measure of the oxygen concentration.
  • The greater the concentration of dissolved oxygen in cells the greater the partial pressure.
  • As partial pressure increases, the affinity of haemoglobin for oxygen increases.
31
Q

What happens to affinity for oxygen during repatriation?

A
  • Oxygen is used up and the partial pressure decreases so = affinity of oxygen decreases.
  • Oxygen is released in respiring tissues where needed.
  • The haemoglobin returns to the lungs to be loaded again.
32
Q

What do oxygen dissociation curves tell us?

A
  • The change in haemoglobin saturation as partial pressure changes.
  • The saturation of haemoglobin is affected by its affinity for oxygen, therefore when partial pressure is high, haemoglobin has a high affinity for oxygen, so it is highly saturated.
33
Q

How does saturation affect oxygen affinity?

A
  • After bing to the first oxygen, the affinity of haemoglobin for oxygen increases due to a change in shape, making it easier for the other oxygen molecules to bind.
34
Q

How is fetal haemoglobin different to adult?

A
  • It needs to be better at absorbing oxygen because by the time oxygen reaches the placenta, oxygen saturation of the blood has decreased.
  • So fetal haemoglobin has a higher affinity for oxygen.
35
Q

How does the partial pressure of carbon dioxide affect the affinity of haemoglobin?

A
  • Presence of carbon dioxide, the affinity of haemoglobin for oxygen decreases, causing it to be released.
  • This is BOHR EFFECT
36
Q

What is the circulatory system in mammals?

A
  • Closed double circulatory system.
  • One pumps bloods to the lungs to be oxygenated whilst the other is large and string and pumps oxygenated blood around the body.
37
Q

What’s is the atrium?

A

Thin walled and elastic, the atrium can stretch when filled with blood

38
Q

What is a ventricle?

A

Thick muscular wall to pump blood around the body or to the lungs

39
Q

What is the name of the valves between the atria and ventricles?

A

Atrioventricular valves
(Bicuspid and Tricuspid valves)

40
Q

what is the name of the values between the ventricles and the aorta or pulmonary artery?

A

Semi-lunar valves

41
Q

What is the aorta?

A

Connected to the left ventricular and carries oxygenated blood to the body

42
Q

What is the pulmonary artery?

A

Connected to the right ventricle and carries deoxygenated blood to the lungs where it is oxygenated and the carbon dioxide is removed

43
Q

What is the pulmonary vein?

A

Connected to the left atrium and brings oxygenated blood back from the lungs

44
Q

What is the vena cava?

A

Connected to the right atrium sand brings deoxygenated blood back from the tissues except the lungs

45
Q

What is the term for when a heart can initiate its own contraction?

A

Myogenic

46
Q

What is the sinoatrial node and what does it do?

A
  • Region of specialised fibres which are the pacemaker of the heart.
  • They initiate a wave of electrical stimulation which causes the atria to contract at roughly the same time.

Biology (5 decks)

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