B8.1 - Gas exchange

Question 1

Exchange surfaces are

Answer 1

surfaces that are adapted to maximize the efficiency of gas and solute exchange

Question 2

Why do animals need to exchange gases

Answer 2

to supply oxygen for respiration in cells and to remove waste products of respiration i.e CO2

Question 3

How are gases exchanged at surfaces

Answer 3

by diffusion

Question 4

What increases gas exchange surface

Answer 4

a large surface area
A thin membrane so shorter distance that the substance has to diffuse
A good blood supply
Good ventilation to deliver more O2 and remove CO2 from the body

Question 5

What is breathing

Answer 5

the process of ventilating the lungs with air

Question 6

Name the steps to gas exchange within the lungs

Answer 6

Air enters through the nose and mouth
It passes over the larynx where it can be used to make sounds.
Air then travels down the trachea to the lungs
It divides into two tubes called bronchi
Bronchi divide into smaller bronchioles
There are a network of bronchioles
They divide and end up with tiny air sacs called alveoli

Question 7

What are the features of the alveoli

Answer 7

Millions of small tiny air sacs
They are surrounded by a network of capillaries allowing O2 and CO2 to be exchanged between blood in capillaries and air in lungs

Question 8

Describe how alveoli adapted for gas exchange?

Answer 8

Thin membranes one cell thick for shorter diffusion distance.
Good blood supply (surrounded by many capillaries) to maintain a low concentration of oxygen in blood
Large surface area in the lungs so more oxygen can diffuse into the blood at the same time
Kept clear by cilia removing mucus.
High concentration gradients for gases

Question 9

What cells secrete mucus into the linings of the trachea, bronchi and bronchioles

Answer 9

goblet cells

Question 10

Why are goblet cells necessary

Answer 10

they secrete mucus to trap microorganisms and dust particles that are breathed in and moisturize to keep vital organs from drying out

Question 11

The lining of the trachea and bronchi are covered in tiny hairs called

Answer 11

cilia

Question 12

What is the function of cilia

Answer 12

to sweep in a co-ordinated motion to move mucus up from the lungs up the trachea and back into the mouth where it can be swallowed.

Question 13

Alveoli’s are where

Answer 13

oxygen and carbon dioxide diffuse into and out of the blood

Question 14

In the lungs the blood absorbs

Answer 14

oxygen from inhaled air and circulate it around the body

Question 15

The lungs absorb

Answer 15

carbon dioxide from the blood and exhale it into the air

Question 16

describe what happens during inhalation

Answer 16

the internal intercostal muscles contract and external intercostal muscles relax
the ribcage moves upwards and outwards
The diaphragm contracts and becomes flattened and less dome shaped
these two both increase volume of thorax (chest cavity) making pressure inside lower than outside making air rush into the lungs

Question 17

describe what happens during exhalation

Answer 17

the internal intercostal muscles relax and the external intercostal muscles contract
the ribcage moves downwards and inwards
The diaphragm relaxes and becomes more dome shaped
This decreases the volume in the thorax (chest cavity) making the pressure inside more than the outside

Question 18

Why is the trachea made up of rings of cartilage

Answer 18

to stop the trachea from collapsing in on itself and closing

Question 19

What are the percentages for inspired air

Answer 19

oxygen - 21%
carbon dioxide - 0.04%
water - variable

Question 20

What are the percentages for expired air

Answer 20

oxygen 16%
carbon dioxide - 4.5%
water vapor - high

Question 21

Explain why the composition of inspired and expired air is different

Answer 21

Oxygen we inspire is used in respiration so percentage of oxygen expired is lower

CO2 breathed in is less than expired as CO2 is produced by respiration so percentage of expiration increases

Water vapor concentration increases because water evaporates from the moist linings of the alveoli into the expired air as a result of warmth of the body so increase expired.

Question 22

What investigation can be used to compare CO2 inspired and expired

Answer 22

A limewater test for CO2

Question 23

Why is limewater used to test for comparing CO2 inspiration and expiration

Answer 23

Lime water is a clear solution
It reacts with CO2 and turns cloudy
The tubes in the experiment show that expired air contains more carbon dioxide than inspired air

Question 24

Explain why breathing rate increase when exercising

Answer 24

It increase the rate of respiration in cells creating a higher concentration of CO2 in the blood.

If more CO2 is produced it needs to be removed quickly
The brain detects this and receptors send impulses in the lungs to cause breathing to become deeper and faster

This means more CO2 can be breathed out at a quicker rate and more oxygen and be breathed in

Question 25

What piece of equipment can be used to test for rate and volume of someone's breathing

Answer 25

spirometer

Question 26

What are the steps for an investigation on the effect of exercise intensity on breathing rate

Answer 26

Set a timer for 15 seconds Sit still and don't move and measure your pulse for BPM. You can do this by measuring your pulse from your neck or wrist After the 15 seconds do the calculator 4 x amount of beats counted. Now choose an intense exercise like high knees and set a metronome to 30 60 and 120 beats to measure the intensity of the exercise. Do it for 2 minutes for each timed metronome and count how many beats in 15 seconds again. Rest between to allow breathing rate to stabilize. DV: The BPM measured IV: The different intensity of exercise CV: Same exercise used and same person for exercise,

Question 27

Describe the trend for the effect of exercise intensity on breathing rate

Answer 27

As the intensity of exercise increases the breathing rate also increases

Question 28

Why is tobacco smoke dangerous

Answer 28

Tobacco smoke contains mixtures of chemicals that are dangerous to the cells

Question 29

Over time tobacco smoke can lead to diseases like

Answer 29

Chronic obstructive pulmonary disease (COPD) a collection of lung diseases that includes bronchitis, emphysema, lung cancer and coronary heart disease.

Question 30

What are the effects of carbon monoxide on gas exchange

Answer 30

it can replace oxygen in hemoglobin and prevent the body from absorbing too much oxygen

Question 31

What are the effects of nicotine on gas exchange

Answer 31

it is addictive and narrows blood vessels increasing blood pressure and the risk of coronary heart diseases (CHD)

Question 32

What are the effects of tar on gas exchange

Answer 32

the sticky substance can coat cells of the trachea, bronchi and bronchioles leading to coughing and cell damage. There is a decrease in rate of gas exchange and can lead to cancer of the lungs, throat and mouth