Gas exchange and respiration

Question 1

What features do all gas exchange surfaces have in common that maximise the rate of gas exchange?

Answer 1

• Large surface area, to allow faster diffusion of gases across the surface
• Thin walls- so that diffusion distance remains short
• Good ventilations with air so that diffusion gradient can be maintained
• Good blood supply to maintain a high concentration gradient so diffusion can occur faster.

Question 2

what are alveolus

Answer 2

Tiny air sacs at the end of the bronchioles (tiny branches of air tubes in the lungs).

Question 3

What process occurs at the alveoli?

Answer 3

The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out.

Question 4

How many alveoli does each lung contain approximatly?

Answer 4

Around 250 million alveoli

Question 5

What are the features that all exchange surfaces have in common? ex. villi, root hair cells

Answer 5

• Large surface area
• Good blood supply
• Steep concentration gradient

These features allow the efficient movement of substances across their surface by diffusion, active transport and osmosis

Question 6

Ribs

Answer 6

Bone structure that protects internal organs such as the lungs

Question 7

Intercostal muscle

Answer 7

Muscle between the ribs which control their movement causing inhalation and exhalation

Question 8

Diaphragm

Answer 8

Sheet of connective tissues and muscle at the bottom of the thorax that helps change the volume of the thorax to allow inhalation and exhalation

Question 9

Trachea

Answer 9

Windpipe that connects the mouth and nose to the lungs

Question 10

Larynx

Answer 10

Also known as the voice box, when air passes across here we are able to make sounds

Question 11

Bronchi (PL)

Answer 11

Large tubes branching off the trachea with one bronchus (SIN)

Question 12

Bronchioles

Answer 12

Bronchi split to form smaller tubes called bronchioles in the lungs connected to alveoli

Question 13

Alveoli

Answer 13

Tiny air sacs where gas exchange takes place

Question 14

Clavicle

Answer 14

Collar bone

Question 15

Why is the composition of inhaled air different to the one of exhaled air?

Answer 15

Air that is inhaled differs in gas composition to air that is exhaled, this is due to the process known as gas exchange that takes place in the alveoli.

Question 16

What happens during gas exchange in the alveoli?

Answer 16

During gas exchange in the alveoli, oxygen enters the blood from the alveoli and CO2 and water vapour leave the blood to enter the alveoli

Question 17

What is the composition of inhaled air?

Answer 17

Inhaled air contains around 21% of oxygen, 0.04% of CO2, 0.2-4 % water vapour and 78% nitrogen

Question 18

What is the composition of exhaled air?

Answer 18

Exhaled air contains 16% of oxygen, 4% CO2, 5-7 % of water vapour and 78% of Nitrogen

Question 19

Why are there two sets of intercostal muscles?

Answer 19

Muscles are only able to pull on bones, not push them. This means that there must be two sets of intercostal muscles, one to pull the rib cage up and another to pull it down

Question 20

Where can the intercostal muscles be found?

Answer 20

One set of them can be found outside of the ribcage (external intercostal muscle) and the other set is found inside the ribcage (internal intercostal muscle)

Question 21

What does cartilage surround?

Answer 21

The trachea and the bronchi

Question 22

What is the function of the cartilage?

Answer 22

To support the airways and keep them open during breathing

Question 23

What could happen if cartilage wasn’t present?

Answer 23

If they were not present then the sides could collapse inwards when the air pressure inside the tubes drops.

Question 24

What is the function of the diaphram?

Answer 24

It is a thin sheet of muscle that separates chest activity from the abdomen. It is responsible for controlling ventilation in the lungs.

Question 25

What happens when the diaphragm contracts?

Answer 25

When the diaphram contracts, it flattens and this increases the volume of the chest cavity (thorax), which leads to decreased air pressure inside the lungs (thorax) , relative to outside the body, drawing air in. This process is known as inhalation, during this process, the external set of intercostal muscles contract to expand the ribcage.

Question 26

What happens when the diaphragm relaxes? exhalation OR expiration

Answer 26

When the diaphragm relaxes, it moves up, becoming dome- shaped , which causes an increase in pressure in the lungs (thorax), a decrease in volume of the thorax and causes air to be forced out of lungs. The external intercostal muscles relax, allowing the ribcage to drop inwards and downwards.

Question 27

Why is there a diffrence in concentration of oxygen levels in inspired and expired air?

Answer 27

Oxygen is removed from the blood by respiring cells so blood returning to lungs has a lower oxygen concentration than the air in the alveoli which means oxygen diffuses into the blood in the lungs

Question 28

Why is there a difference in the concentration of CO2 in expired and inspired air?

Answer 28

Carbon dioxide is produced by respiration and diffuses into the blood from respiring cells; The blood transports the carbon dioxide to the lungs where it diffuses into the alveoli as theres a higher concentration in the blood than in the air of the alveoli.

Question 29

Why is there a diffrence in the concentration of water vapour in expired and inspired air?

Answer 29

Water evaporates from the moist lining of the alveoli into expired air as a result of the warmth of the body.

Question 30

Why are the levels of nitrogen the same in expired and inspired air?

Answer 30

Nitrogen gas is very stable and so cannot be used by the body, for this reason its concentration does not change in inspired or expired air

Question 31

Why does frequency of breathing increase during exersice?

Answer 31

Because muscles are working harder and aerobically, respiring more and they need more oxygen to be delivered to them (and Co2) to keep up with the energy demand.

Question 32

What happens when the aerobic respiration can't meet the energy demands?

Answer 32

If they cannot meet the energy demand they will also respire anaerobically, producing lactic acid.

Question 33

What happens to lactic acid after exercise has finished?

Answer 33

The lactic acid that has built up in muscles needs to removed as it lowers the pH of cells and can denature enzymes catalysing cell reactions. It can only be removed by combining it with oxygen, this is known as "repaying the oxygen debt"

Question 34

What happens after Co2 is produced as a product of aerobic respiration?

Answer 34

Co2 levels increase in the muscle cells, this co2 diffuses out of the cells into the blood plasma, this causes a slight drop in pH so the blood becomes slightly more acidic.

Question 35

Where does the blood with CO2 from aerobic respiration flow?

Answer 35

The blood flows around the circulatory system and passes to the brain where the increased CO2 levels are detected by chemoreceptors in the brain

Question 36

What are chemoreceptors, where are they located?

Answer 36

Chemoreceptors are cells that detect chemical changes in the body, they can detect changes in blood gas levels, as well as changes in pH. They are located in the medulla oblongata of the brain

Question 37

What does the brain do to increase the rate and depth of muscle contraction?

Answer 37

The brain sends nerve impulses to the diaphragm and the intercostal muscles to increase the rate and depth of muscle contraction. The rate of inspiration increases, along with the volume of air moved in and out with each breath. This results in greater absorption of oxygen and removal rate of co2. This supports the increased rate of respiration

Question 38

Which processes require enzymes?

Answer 38

Aerobic respiration, anaerobic respiration in yeast and animals, all catabolic reactions

Question 39

why does anaerobic respiration of glucose release less energy in muscle cells than aerobic respiration?

Answer 39

In aerobic respiration, glucose is completely broken down into carbon dioxide and water. However, in anaerobic respiration, the breakdown of glucose is incomplete. The end product of anaerobic respiration is lactic acid instead of carbon dioxide and water.

Question 40

What helps oxygen to be absorbed rapidly in the lungs?

Answer 40

Alveoli have thin walls and a large surface area

Question 41

which materials are excreted by kidneys

Answer 41

The kidney regulates/controls the water and salt content and removes urea. It is excreted in urine.. The filtered excess water, salts and urea form a liquid called urine

Question 42

which process uses the greatest amount of energy

Answer 42

Respiration is the process uses the greatest amount of energy.

Question 43

how is an effective oxygen supply maintained between the alveoli and the lung capillaries

Answer 43

Effective oxygen supply between the alveoli and lung capillaries is maintained by (large surface area, thin diffusion barrier) and (high blood flow, steep diffusion gradient, hemoglobin binding). These factors ensure a continuous and efficient oxygen supply to the blood while removing carbon dioxide.