Gas Exchange in Humans

Question 1

Why do humans need to get oxygen into blood?

Answer 1

For respiration

Question 2

What do they need to get rid of made by respiring cells?

Answer 2

Carbon dioxide

Question 3

Where does air enter as soon as you breathe in?

Answer 3

Enters into the trachea (windpipe)

Question 4

What is the trachea spilt into?

Answer 4

Bronchi- one bronchus leading to each lung

Question 5

Where do the bronchioles end in small air sacs called what?

Answer 5

Alveoli (gas exchange takes place)

Question 6

What do the ribcage, intercostal muscle and diaphragm work together to do?

Answer 6

Move air in and out

Question 7

What does ventilation consist of?

Answer 7

Inspiration

Expiration

Question 8

What is an inspiration?

Answer 8

Breathing in

Question 9

What is expiration?

Answer 9

Breathing out

Question 10

What is ventilation controlled by movements of?

Answer 10

• Diaphragm
• Internal and external intercostal muscles
• Ribcage

Question 11

Diagram of inspiration

Answer 11

Question 12

Process of inspiration

Answer 12

• The external and diaphragm muscle contract
• Cause ribcage to move upwards and outwards causing the diaphragm to flatten
• Increasing volume of thoracic cavity
• As volume of thoracic cavitiy increases , pressure decreases (below atmospheric pressure)
• Air flows from an area of higher pressure to an area of lower pressure (down a pressure gradient)
• Air flows down the trachea and into the lungs

Question 13

What type of process is an inspiration?

Answer 13

An active process - requires energy

Question 14

Diagram of expiration

Answer 14

Question 15

Process of expiration

Answer 15

• External intercostal and diaphragm muscle relax
• Ribcage moves downwards and inwards and diaphragm becomes curved again
• The volume of the thoracic cavity decreases, causing pressure to increase (above atmospheric pressure)
• Air is forced to down the pressure gradient (high to low) and out of lungs

Question 16

What type of process is normal expiration?

Answer 16

It is a passive process -it doesn’t require energy

Question 17

Example of expiration being forced

Answer 17

Blowing out candles on your birthday cake

Question 18

Process of forced expiration

Answer 18

• External intercostal muscles relax
• Internal intercostal muscles contract, pulling ribcage further down and in
• During this time, the movement of the two sets of intercostal muscles are said to be antagonistic (opposing)

Question 19

What is each alveolus made up of?

Answer 19

A single layer of thin, flat cells called alveolar epithelium

Question 20

What is the resting shape of the diagram?

Answer 20

Curved - dome position

Question 21

What is the alveoli surrounded by?

Answer 21

By a network of capillaries

Question 22

How does oxygen move in humans?

Answer 22

• Oxygen from the air moves down the trachea, bronchi and bronchioles into the alveoli
• This movement happens down a pressure gradient
• Once in alveoli, 02 diffuses across the alveolar epithelium and the capillary endothelium into capillary itself
• Into the haemoglobin in the blood
• Happens down a diffusion gradient

Question 23

How does c02 move in alveoli?

Answer 23

Diffuses into the alveoli from the blood and is breathed out

Question 24

How is alveoli adapted?

Answer 24

• A thin exchange surface: - alveolar epithelium is only one cell thick. There is short diffusion pathway (increase diffusion)
• Large surface area : Large number of alveoli - large SA for gas exchange

Question 25

How is gas exchange adapted?

Answer 25

Steep concentration gradient of oxygen and carbon dioxide between alveoli and capillaries increasing the rate of diffusion this is constantly maintained by the flow of blood and ventilation

Question 26

Describe two ways in which lungs are adapted for efficient gas exchange

Answer 26

* Lungs contain millions of tiny air sacs called alveoli - creating large surface area for gas exchange * Alveolar epithelium is only one cell thick , a short diffusion pathway * Alveoli is surrounded by a dense network of capillaries which maintains a steep concentration gradient of oxygen and carbon dioxide between alveoli and blood

Question 27

Does capillaries have thin epithelium?

Answer 27

Yes offering short diffusion pathway

Question 28

What is the ventilation?

Answer 28

Bring in air with high concentration of C02 replaces air with low concentration of C02

Question 29

What is circulation?

Answer 29

Replaces blood high in oxygen with blood low in 02

Question 30

Why does the volume of oxygen that has to be absorbed and the volume that must be removed are large in mammals? They have evoled specialised surfaces called lungs for gas exchange between air and blood

Answer 30

* Relatively large organisms with a large volume of living cells * Maintain a high body temperature which is related to this having high metabolic and respiratory rates

Question 31

Why are the lungs site of gas exchange inside of the body?

Answer 31

* Air is not dense enough to support and protect these delicate structures * Body as a whole would otherwise lose a great deal of water and dry out

Question 32

List in the correct sequence all structures that air passes through on its journey from the gas-exchange surface of the lungs to the nose

Answer 32

Alveoli Bronchioles Bronchus Trachea Nose E

Question 33

How is the cartilage important supporting the trachea?

Answer 33

Prevents the trachea collapsing as the air pressure inside falls when breathing in

Question 34

What is the tracheal walls made up of?

Answer 34

Muscle lined with ciliated epithelium and goblet cells

Question 35

Advantage of bronchi

Answer 35

* Produce mucus to trap dirt particles and have cilia that move the dirt-laden mucus towards the throat

Question 36

What are the walls of bronchioles made up of?

Answer 36

Walls lined with epithelial cells Muscle allow to constrict so they can control their flow of air in and out of alveoli

Question 37

How has alveoli having collagen and elastic fibres important?

Answer 37

Allow alveoli to stretch as they fill with air when breathing in Spring back during breathing in order to expel the C02

Question 38

Explain how the cells lining the trachea and bronchus protect the alveoli from damage?

Answer 38

The cells produce mucus that traps particles of dirt and bacteria in the air breathed Cilia on these cells move this debris up into the trachea and into the stomach

Question 39

Explain why these figures in table were given per gram of tissue

Answer 39

Easier for comparison Organs differ in size

Question 40

There is a greater percentage reduction in blood flow to the diaphragm than the lungs during dive. Explain the advantage to a diving seal of : Blood continuing to flow the lungs

Answer 40

Some oxygen still in lungs

Question 41

There is a greater percentage reduction in blood flow to the diaphragm than the lungs during dive. Explain the advantage to a diving seal of : Large reduction in blood flow to the diaphragm

Answer 41

There is more blood for other organs to remove C02

Question 42

A mountain climber is climbing at altitiude where there is less oxygen Suggest how this will affect gas exchange in alveoli

Answer 42

Less air - less oxygen would be inhaled in each breath The concentration gradient of oxygen between alveoli and capillaries are less steep Slowing rate of diffusion