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Biology Mrs Champion > Exchange Surfaces > Flashcards

Exchange Surfaces Flashcards

1
Q

What is an exchange surface?

A
  • A specialised area that is adapted to make it easier for molecules to cross from one side of the surface to the other
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2
Q

How does a large surface area help efficiency?

A
  • More space for molecules to diffuse
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3
Q

How does a thin barrier help efficiency?

A
  • Short diffusion distance
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4
Q

How does a permeable membrane help efficiency?

A
  • Allows desired molecules through
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5
Q

How does a good blood supply help efficiency?

A
  • Keeps concentration high so diffusion gradient is high
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6
Q

How does ventilation help efficiency?

A
  • Maintains diffusion gradients of gases by bringing/removing 02 and CO2
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7
Q

Explain the adaptions and functions of the small intestine

A

Adaptions:
- Villi are 1 cell thick so allows short diffusion distance
- Network of blood capillaries in each villi to maximise amount of exchange

Functions:
- Rich blood supply to allow absorption to take place efficiently
- Villi 1 cell thick so digested nutrients can cross walls to reach blood capillaries

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8
Q

What are microvilli?

A
  • Located on surface of epithelial cells
  • Increase surface area of small intestine
  • Good at absorption of nutrients
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9
Q

Explain the adaptions and functions of the liver

A

Adaptions:
- Hepatocytes are main liver cells
- Spaces between hepatocytes increases amount of 02

Functions:
- Produces bile which breaks down fats in small intestine
- Regulates blood levels of amino acids
- Absorbs nutrients
- Receives O blood from heart via hepatic artery
- Receives D blood from hepatic portal vein

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10
Q

Explain the adaptions and functions of the alveoli

A

Adaptions:
- Good blood supply, network of capillaries
- Large surface area
- Thin wall layers, 1 epithelial cell thick
- Elastic recoil, tissues stretch as air enters and return back to normal, helps squeeze air out

Functions:
- Moves O2 and CO2 molecules in&out of bloodstream
- Large SA helps increase rate of gas exchange
- Capillaries close to walls = short diffusion distance

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11
Q

Why is the lining of alveoli moist?

A
  • Allows gases to dissolve which allows them to diffuse at a faster rate
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12
Q

Explain the adaptions and functions of root hair

A

Adaptations:
- Large SA beneficial in water and nutrient absorption in soil
- Thin surface layer so diffusion and osmosis take place quick
- Large structures to take up mineral ions and water from soil

Functions:
- Small sizes so can penetrate easily between soil particles
- Large amounts of mitochondria releases energy from glucose in respiration to provide energy needed for AT

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13
Q

Explain the adaptions and functions of hyphae

A

Adaptations:
- Large network
- Firm cell wall
- Cross wall structures called septa dividing hyphae into compartments

Functions:
- Feathery filaments making up multicellular fungi
- Release enzymes and absorb nutrients from food source
- Branches out and creates large network called mycelium

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14
Q

Why do large, active organisms need special surfaces for exchange?

A
  • Large animals have a small SA:Vol
  • Means there is not enough surface to provide many of the central cells with the supplies they need as the distance the substances need to travel is too great
  • The more active the organism, the more supplies and waste products will need to be transported
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15
Q

Name the air sacs and why there are many air sacs in the lungs

A
  • They are called alveoli and they have a large SA for diffusion
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16
Q

Name the type of epithelium in the walls of the air sacs

A
  • Flattened epithelium
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17
Q

Air sacs contain many elastic fibres
Explain the role of these elastic fibres during ventilation

A
  • Enables the air sacs to expand and return to their original shape as they recoil which allows air to be squeezed out
  • Prevents alveoli from bursting
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18
Q

Explain how refreshing the air in the air sacs helps to maintain a steep diffusion gradient

A
  • Alveoli has lots of oxygen supply met with deoxygenated blood
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19
Q

Explain inhalation (inspiration)

A
  • External intercostal muscles contract to raise rib cage
  • Diaphragm contracts to become flatter pushing digestive organs down
  • Volume of chest cavity increases
  • Pressure of thorax decreases
  • Air moves into lungs
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20
Q

Explain exhalation (expiration)

A
  • External intercostal muscles relax and ribs fall
  • Diaphragm relaxes and is pushed up by displaces organs underneath
  • Volume of chest cavity decreases
  • Pressure in lungs and thorax increases
  • Air moves out of lungs
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21
Q

How are 2 opposing concentrations gradients maintained?

A
  • Ventilation replenishes needed oxygen and gets rid of waste CO2
  • This ensures conc gradients are maintained so that these gases moves
  • Blood transports both o2 and CO2 separate so both can move at once
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22
Q

What is a spirometer? How does it work?

A
  • Airtight oxygen-filled chamber
  • As person breathes in and out, the lid moves up and down
  • Chamber gas volume decreases with time
  • Any Co2 is breathed out by soda lime
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23
Q

What is the breathing rate?

A
  • Number of breaths taken per minute
24
Q

What is ventilation rate?

A
  • Total volume of air inhaled in one minute
25
Q

Do fish have a large or small SA:Vol?

A
  • Small
26
Q

What direction does water flow over gills?

A
  • 1 direction
27
Q

What are features of gills?

A
  • Large SA
  • Good blood supply
  • Thin layers
28
Q

Describe how single-called organised exchange respiratory gases

A
  • By the process of diffusion
29
Q

The method of gas exchange is only possible in very small organisms. Explain why

A
  • Small organisms often have thin cell walls
  • So distance from gas exchange surface to inside of organism is short enough so that diffusion can be efficient
30
Q

Why do insects have high oxygen demands?

A
  • They are highly active
31
Q

Why can little/no gas exchange take place through insects skin?

A
  • They have an exoskeleton
  • Outer layer is very penetrable and can let gases in
32
Q

How are spiracles opened and closed?

A
  • By sphincters
  • Kept closed as much as possible to reduce water loss
33
Q

For larger insects with high energy demands the tracheal system can’t supply sufficient oxygen so what else can help?

A
  • Mechanical ventilation = thorax actively pumps out air into tracheal system which increases the body volume and changes the pressure in tracheal system. Air is forced in and out of system as new pressure fluctuates
  • Collapsible tracheae = acts as reservoirs, they increase amount of air moved through tracheal system. Mechanical ventilation causes them to inflate/deflate
34
Q

What type of organisms require a specialised transport system?

A
  • Multicellular organisms
35
Q

What is an open circulatory system?

A
  • Nutrients and waste moved through body with haemolymph which flows freely from heart to body cavity
  • Means the haemolymph is under low pressure
  • The transport medium returns to the heart
36
Q

What is a closed circulatory system?

A
  • Circulates blood through a series of vessels in body
  • Allows quick flow and high pressure
  • Cells are bathed in tissue fluid so nutrients reach all cells
  • Blood returns directly to heart
  • Exchange surfaces are needed as blood enters and leaves blood vessels via diffusion
37
Q

What uses a single circulatory system and explain features

A
  • Fish
  • Reduced blood pressure as it passes through 2 sets of small capillaries
  • Blood flow is slow
  • Limits rate at which oxygen and nutrients are delivered to respiring tissues
38
Q

What uses a double circulatory system and explain features

A
  • Mammals and humans
  • Heart increases blood pressure to ensure it flows fast to body tissues
  • Blood only passes through 1 capillary network which maintains blood pressure
39
Q

What are the 3 common components of blood vessels?

A
  • Elastic fibres = stretch and recoil to provide flexibility
  • Smooth muscle = changes lumen size by relaxing and contracting
  • Collagen = provides structural support to maintain vessel shape
40
Q

How are veins adapted?

A
  • One way valves to prevent back flow of blood
  • Large veins running between large muscles and squeeze blood towards heart when contracting
41
Q

What do arteries do?

A
  • Transport blood AWAY from heart to tissues
42
Q

What do arterioles do?

A
  • Arteries branch into narrower blood vessels called arterioles which transport blood into capillaries
43
Q

What do veins do?

A
  • Transport blood to the heart
44
Q

What do venues do?

A
  • Narrower blood vessels transport blood from capillaries to veins
45
Q

What is the structure of arteries ?

A
  • Walls have 3 layers = tunica externa, tunica media, tunica intima
  • Tunica intima made up of endothelial layer, connective tissue and elastic fibres
  • Endothelium is 1 cell thick, smooth and reduces friction
  • Tunica media is thick to withstand high pressure
  • Tunica externa made from collagen so protect vessels from damage
  • Arteries have narrow lumen to maintain high blood pressure
46
Q

What is the structure of veins

A
  • Return blood to the heart
  • Tunica media is thinner in veins
  • Lumen of veins is larger than artery ensuring blood returns at a good speed and reduces friction between blood and endothelial layer
  • Contains valves preventing back flow of blood
47
Q

What is the structure of venules?

A
  • Connect capillaries to veins
  • Few or no elastic fibres and a large lumen
  • Blood is at low pressure so no need for muscular layer
48
Q

What are capillaries?

A
  • Type of blood vessel
  • Thin walls which are ‘leaky’ allowing substances to leave
  • Form capillary beds important for exchange surfaces
  • Small diameter
  • Wall is single later of endothelial cells , 1 cell thick reducing diffusion distance
49
Q

What is blood? What is in it?

A
  • Plasma = liquid part of blood, dilute solution of salts, glucose, amino acids…
  • WBC (leucocytes) = involved in immune system
  • Placelets = blood clotting
  • RBC (erythrocytes) = carrying oxygen
50
Q

What is tissue fluid and how is it made?

A
  • Liquid that surrounds and bathes the cells allowing for transport between blood and cells by diffusion
  • Tissue fluid is plasma without plasma proteins and blood cells in it
  • Occurs as capillary walls are partially permeable
51
Q

What is tissue fluid the result of an interplay of?

A
  • Hydrostatic and oncotic pressure
52
Q

What is hydrostatic pressure?

A
  • The pressure of the blood from heart contractions
  • Forces fluid out of capillaries
  • Blood fluid moves out through tiny gaps in capillary walls
  • Dissolved gases move with it, large plasma proteins dont
53
Q

Explain osmotic pressure (osmosis)

A
  • A net loss of water from the capillaries give the capillaries a negative water potential
  • Water moves down the water potential gradient into capillaries
  • More fluid is lost from capillary at arterial end than gained = net loss
54
Q

What is the equation for filtration pressure?

A

Hydrostatic pressure - oncontic pressure

55
Q

What is lymph?

A
  • Looks same as tissue fluid, clear, sticky white/yellow
  • Not all tissue fluid returns to capillaries, excess drains into lymphatic system where it forms lymph
  • Contains lipids
56
Q

What are lymph nodes?

A
  • Intercept bacteria from lymph
  • Produces antibodies passed into blood and kills pathogens

Biology Mrs Champion (5 decks)

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