3.1.1 - Exchange Surfaces (set A - Diffusion And Addaptions Of The Lungs)

Question 1

Define the process diffusion?

Answer 1

the net movement of particles from an area of higher concentration to an area of lower concentration down a concentration gradient until equilibrium is reached

• passive process

Question 2

Explain briefly the link between the SA:V ratio and an organisms size?

Answer 2

As an organism increases in size their SA:V ratio decreases so a larger organism will have a smaller SA:V ratio

• diffusion is slower

Question 3

Give two reasons why diffusion is enough to supply the needs of single-called organisms?

Answer 3

• low metabolic activity - oxygen demands and carbon dioxide production of the cells are relatively low
• large SA:V ratio of the organism

Question 4

Why is diffusion not enough for larger organisms?

Answer 4

• made up of more cells - this means they will have a higher metabolic activity then a single called organism
• require and produce more substances - the distance these substances diffuse across increases - slower diffusion
• SA:V ratio is smaller so gasses can’t be exchanged fast enough in large enough amounts to allow for survival

Question 5

Give 4 examples of features required for effective exchange surfaces?

Answer 5

• increased surface area
• thin layers
• good blood supply
• ventilation to maintain diffusion gradient

Question 6

How does increased surface area help provide an effective exchange surface - give some exmaples of this?

Answer 6

Provides the area needed for exchange and overcomes the limitations of the SA:V ratio of larger organisms - for example root hair cells in plants and villi in small intestines

Question 7

How do thin layers help to provide an effective exchange surface give some examples of this?

Answer 7

The distance that substances have to diffuse are short, making the process fast and efficient

• examples include the alveoli in the lungs (1 cell thick) and villi in small intestine

Question 8

How does a good blood supply help to provide an effective exchange surface?

Answer 8

ensures substances are constantly delivered to and removed from the exchange surface, which maintains a steep concentration gradient for diffusion - example the gills of a fish and alveoli in lungs

Question 9

How does ventilation help provide an effective exchange surface?

Answer 9

For gases a ventilation systems helps to maintain concentration gradients and makes the process more efficient - for example the alveoli and the gills of a fish where ventilation means a flows of water carrying dissolved gases

Question 10

Give two reasons why organisms need to exchange substances - explain them?

Answer 10

• supply every one of its cells with substances like glucose and oxygen - needed for respiration to release energy to drive metabolic reactions or move substances across membranes
• remove waste products which might damage the cell

Question 11

Why is it important that substances and products are taken in and removed quickly?

Answer 11

To help maintain a steep concentration gradient to allow for efficient diffusion

• maintain organisms survival and metabolic reactions

Question 12

Why do humans need a system like the lungs for exchange of gases?

Answer 12

• Humans have a small SA:V ratio and a high metabolic rate as humans are active and require energy to maintain their temperature
• we need lots of oxygen for respiration and therefore produce lots of carbon dioxide which can not be supported just by diffusion across a membrane

Question 13

Give three key structures of the nasal cavity, explain how they are important?

Answer 13

• hairy lining secretes mucus to trap dust and pathogens, protects lung tissue
• moist surface increases the humidity of the incoming air, reduces evaporation
• large SA and good blood supply, warms the air to body temp

Question 14

Explain how the nasal cavity is adapted to keep the entering air at a similar temperature to air already in there?

Answer 14

A large surface area and good blood supply, warms the air to body temperature which means the temp of the entering air is already the same as the temp of the air in the lungs

• done to prevent any damage to delicate lung tissue

Question 15

What is the trachea, briefly explain its structure - what does it do?

Answer 15

Main airway carries warm, moist air from the nose down into the chest - wide tube supported by incomplete flexible cartilage rings which allows food to move easily down the oesophagus (which is behind the trachea)

Question 16

Explain in depth the structure of the trachea?

Answer 16

Wide tube supported by incomplete rings of strong, flexible cartilage (prevents it from collapsing) inside is lined with ciliated epithelium with goblet cells between and below epithelial cells - goblet cells secrete mucus

Question 17

What is the function of goblet cells - where are they located?

Answer 17

• found in the trachea,nasal cavity, bronchi and larger bronchiole
• secrete mucus which traps pathogens and dust from reaching the alveoli - protects alveoli

Question 18

Why are the epithelium of the trachea, bronchi and bronchiole ciliated?

Answer 18

Cilia beats and wafts the mucus (and trapped pathogens)moving it up towards the throat where it can be swallowed and destroyed in the stomach

• protects lungs from infection

Question 19

What are bronchioles - give brief structure?

Answer 19

Small airways which branch out from the bronchi and end at the alveoli, they have no cartilage rings but do have elastic fibres and smooth muscles in the walls to control their diameter

Question 20

What is the function of elastic fibres - where are they located?

Answer 20

Elastic fibres in the walls of the trachea,bronchi and bronchioles help with breathing out, when you breath in the lungs inflate and the fibres stretch when you exhale the fibres recoil and push the air out

Question 21

What is the function of smooth muscles - where are they located?

Answer 21

Found in the walls of the trachea, bronchi and bronchioles they allow the diameter to be controlled - for example during exercise they relax making the tube wider, means there is less resistance to airflow so air can move in and out easier

Question 22

Explain the importance of smooth muscles in regard to airflow?

Answer 22

Rate of airflow can be controlled - for example, during exercise they relax making the tube wider, means there is less resistance to airflow so air can move in and out easier

Question 23

What are bronchi - what’s its structure?

Answer 23

the two major extensions of the trachea which directly transport the air from the trachea

• similar structure to trachea - same supporting rings of cartilage

Question 24

Describe the structure of bronchi?

Answer 24

Similar to that of the trachea, ciliated epithelium with goblet cells but have smaller supporting pieces of cartilage - also has smooth muscles in walls and elastic fibres

Question 25

What are alveoli - what is their role?

Answer 25

Tiny air sacs which act as the main gas exchange surface of the body found at the end of bronchioles

Question 26

What is the structure of alveoli?

Answer 26

Tiny air sacs consisting of thin flattened epithelial cells along with collagen and elastic fibres - do not have cartilage, goblet cells or cilia

• walls are single cell thick

Question 27

Explain how the aveoli are adapted - mention blood supply and ventilation?

Answer 27

• good blood supply - network of 280 million capillaries, maintains a constant steep concentration gradient
• good ventilation - air moves in and out helped by elastic fibres - maintains steep concentration gradient between blood and air in lungs

Question 28

Explain fully the process which happens when you inhale?

Answer 28

• external intercostal muscles contract, rib cage moves up and out
• diaphragm contracts, causes it to flatten down
• increase volume of the thoracic cavity
• decrease pressure in thorax
• air rushes down a pressure gradient and alveoli inflate

Question 29

Explain fully the process which happens when you exhale?

Answer 29

• external intercostal muscles relax, rib cage moves down and in
• diaphragm relaxes, causes it to move up
• decrease volume of the thoracic cavity
• increase pressure in thorax
• air rushes down a pressure gradient and alveoli deflate

Question 30

Explain how the alveoli are adapted - mention SA and thin layers?

Answer 30

• large SA - and lots of them about 300 to 500 million in each lung
• thin layers - capillaries and epithelial cells of alveoli are single cell thick, short diffusion distance between air in alveolus and blood in capillaries

Question 31

Explain how a peak flow meter can measure the volume of air drawn in and out of the lungs?

Answer 31

Simple device that measures the rate at which air can be expelled from the lungs

• people with asthma will use this to monitor how well their lungs are working

Question 32

explain who peak flow meter can be used for?

Answer 32

People will asthma to measure the rate at which air can be expelled from the lungs

Question 33

Explain how vitalographs can measure the volume of air drawn in and out of the lungs?

Answer 33

• Sophisticated version of the peak flow meter
• patient will breath out as quickly as they can through a mouth piece - graph is produced of the amount of air they breathed out and how quickly it is breathed out

Question 34

Explain how a spirometer can measure the volume of air drawn in and out of the lungs?

Answer 34

Used to measure different aspects of the lung volume, or to investigate breathing patterns

Question 35

Give three different ways the volume of air that is drawn in and out of the lungs can be measured?

Answer 35

• peak flow meter
• vitalogrphs
• spirometer

Question 36

Define tidal volume?

Answer 36

The volume of air that moves into and out of the lungs with each resting breath

• about 500cm^3 in adults at rests

Question 37

Define vital capacity?

Answer 37

The volume of air that can be breathed in, when the strongest possible exhalation is followed by the deepest possible intake of breath

Question 38

Define inspiratory reserve volume?

Answer 38

Is the maximum volume of air you can breathe in over and above a normal inhalation

Question 39

Define expiratory reserve volume?

Answer 39

The extra amount of air you can force out of your lungs over and above the normal tidal volume of air you breath out

Question 40

Define residual volume?

Answer 40

The volume of air that is left in your lungs when you have exhaled as hard as possible

• cannot be measured directly