Unit 5: Respiration, exchange, and transport

Question 1

Define respiration

Answer 1

A chemical process which involves the breakdown of nutrient molecules (specifically glucose) in order to release the energy stored within the bonds of the molecule. Cellular respiration just means the same thing as respiration. Respiration can take place with oxygen (aerobically) or without oxygen (anaerobically).

Question 2

Define aerobic respiration

Answer 2

The chemical reactions in cells that uses oxygen to break down nutrient molecules to release energy.

Question 3

Define anaerobic respiration

Answer 3

Chemical reactions in cells that breakdown nutrient molecules to release energy without using oxygen.

Question 4

State the balanced chemical equation for aerobic respiration (as well as the word equation):

Answer 4

Glucose + Oxygen —> Carbon dioxide + Water

C6H12O6 + 6O2 —-> 6CO2 + 6H2O

(recognise that this is the backwards reaction of photosynthesis)

Question 5

What processes require energy in the human body?

Answer 5

• Muscle contraction (so that we can move parts of our bodies)
• Protein synthesis (by linking amino acids into long chains)
• Cell division (so that we can repair damaged tissues and grow)
• Growth(by making new cells)
• Nerve impulse
• Maintenance of a constant body temperature (37 *C) - so that we can adapt to the changes in external temperature

Question 6

What is the equation for anaerobic respiration in muscles during vigorous exercise / in animals?

Answer 6

Glucose —> Lactic acid

It does produce energy too but you cant put this in the equation.

Question 7

What is the equation for anaerobic respiration in microorganism yeast?

Answer 7

Glucose — alcohol + carbon dioxide

Question 8

In anaerobic respiration in muscles this toxic chemical is produced…

Answer 8

Lactic acid builds up in muscles and blood during vigorous exercise causing a oxygen debt. Lactic acid provides a more acidic environment for you muscle cells - this is what leads to the burning sensation. The lactic acid needs to be oxidised to carbon dioxide and water later. The amount of oxygen required to remove the lactic acid, and replace the body’s reserves of oxygen, is called the oxygen debt. This is why, when the period of activity is over, a person’s breathing rate and heart rate do not return to normal straightaway.

Question 9

Name and identify (in the human respiratory system):

Answer 9

• lungs
• diaphragm
• ribs
• intercostal muscles
• larynx
• trachea
• bronchi
• bronchioles
• alveoli
• associated capillaries

Question 10

State and explain the differences in composition between inspired and expired air

Answer 10

Inspired gas (during inhalation):

• More oxygen
• Less CO2
• Less water vapour

Expired gas (during exhalation):

• Less oxygen
• More CO2
• More water vapour

Question 11

What is the test/practical to see the difference in inspired vs expired air

Answer 11

Use limewater as a test for carbon dioxide
to investigate the differences in composition
between inspired and expired air.

Lime water changes colour when the gas is bubbled through, from colourless to milky. There is more CO2 present in expired air —> it makes limewater change colour more quickly (than inspired air).

Question 12

List the features of gas exchange surfaces in humans…

Answer 12

… limited to large surface area, thin
surface, good blood supply and good ventilation
with air.

• Alveolar walls are very thin – only a single cell thick – reducing the diffusion distance.
• Capillary walls are very thin – only a single cell thick – reducing diffusion distance.
• Alveolar walls are moist, to prevent the cells from drying out and to allow the gases to dissolve in the water on the alveolar walls. This reduces diffusion distance.
• Alveoli have a very high surface area: volume ratio, making diffusion easier.
• Collectively, the alveoli have a huge surface area, making it possible for large amounts of gas to diffuse at the same time.
• Good blood supply and proper ventilation ensure that steep carbon dioxide and oxygen concentration gradients are maintained. Ventilation, or breathing, is the movement of air through the conducting passages between the atmosphere and the lungs. The air moves through the passages because of pressure gradients that are produced by contraction of the diaphragm and thoracic muscles.
• Gas exchange surfaces are close to an efficient transport system to take gases to and from the exchange surface
• Gas exchange surfaces have a good supply of oxygen (mainly brought in by breathing movements)

Question 13

Investigate and describe the effects of physical activity on rate and depth of breathing

Answer 13

During exercise there is an increase in physical activity and muscle cells respire more than they do when the body is at rest. The heart rate increases during exercise. The rate and depth of breathing increases - this makes sure that more oxygen is absorbed into the blood, and more carbon dioxide is removed from it.

Question 14

What is the route that gasses take in the human body?

Answer 14

Pathway of air: nasal cavities (or oral cavity) > pharynx > larynx > trachea > primary bronchi (right & left) > secondary bronchi > tertiary bronchi > bronchioles > alveoli (site of gas exchange)

During gas exchange, oxygen diffuses from the alveoli, across the alveolar membrane and capillary wall, into the bloodstream, to be picked up by the RBCs. Carbon dioxide diffuses from the blood into the alveoli. This causes the partial pressure of oxygen in the alveoli to dwindle and the partial pressure of carbon dioxide in the alveoli to increase.

Note: partial pressure is the pressure of one gas in a mixture of gases. It is proportional to its concentration.

Therefore, inspiration allows the dwindling supply of oxygen in the alveoli to be replenished, and expiration enables the maintenance of a low carbon dioxide concentration.

The steady flow of blood prevents oxygen from building up and keeps bringing more carbon dioxide close to the alveoli.

These two processes help maintain the steep oxygen and carbon dioxide concentration gradient.

Question 15

Explain the differences in the composition of inspired and expired air

Answer 15

When you inspire air, you are breathing in the air in our atmosphere. This is why inspired air has 21% oxygen, 0.04% carbon dioxide and variable water vapour levels.

While that air is in your alveoli, it loses oxygen to your blood and picks up carbon dioxide from your blood. Because the inside of your body is moist – your mouth has saliva, your nasal cavity and airways are lined with mucus, and your alveoli have a thin layer of water inside – a lot of the water evaporates into the air that you inspired.

So when you expire, the air that you expired has less oxygen, more carbon dioxide and more water vapour than atmospheric air. This is why expired air has 16% oxygen, 4% carbon dioxide and is saturated with water vapour.

Question 16

Explain the effects of physical activity on rate and depth of breathing in terms of the increased carbon dioxide concentration in the blood, causing an increased rate of breathing

Answer 16

The brain constantly monitors the pH of the blood. If there is a lot of carbon dioxide or lactic acid in the blood, this causes the pH to fall. When the brain senses this, it sends nerve impulses to the muscles that cause breathing movements, the diaphragm and the intercostal muscles. The nerve impulses stimulate these muscles to contract harder and more often. The result is a faster breathing rate and deeper breaths.

Question 17

Explain the concept of ‘repaying the oxygen debt’

Answer 17

• Frequency and depth of breathing increase when exercising
• This is because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them (and carbon dioxide removed) to keep up with the energy demand
• If they cannot meet the energy demand they will also respire anaerobically, producing lactic acid
• After exercise has finished, the lactic acid that has built up in muscles needs to be 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’
• This can be tested by seeing how long it takes after exercise for the breathing rate and depth to return to normal - the longer it takes, the more lactic acid produced during exercise and the greater the oxygen debt that needs to be repaid

Question 18

Explain the role of goblet cells, mucus and ciliated cells

Answer 18

They protect the gas exchange system from pathogens and particles.

Some of the cells that line the passages through which air moves towards the alveoli are goblet cells. These cells secrete a sticky mucus. As the air passes over the mucus, microorganisms and particles of dust in the air get trapped in it.

There are other cells that have microscopic hair-like extensions called cilia. These beat in a synchronised wave, sweeping the mucus towards the back of the throat. Once there, it is swallowed.

This protects the lungs from any harmful microorganisms, pathogens, that might be in the air, reducing the chance of getting infections in the lungs. It also stops too many particles (eg soot,dust) getting to the lungs where they might cause inflammation.

Question 19

State that tobacco smoking can cause…

Answer 19

chronic obstructive pulmonary disease (COPD), lung cancer and coronary heart disease.

A person may develop COPD - chronic obstructive pulmonary disease. This condition includes the diseases chronic bronchitis and emphysema . In COPD: smoking damages the bronchioles and can eventually destroy many of the alveoli in the lungs.

Question 20

Describe the effects on the gas exchange system of tobacco smoke and its major toxic components, limited to carbon monoxide, nicotine and tar

Answer 20

• Chemicals in cigarettes include:
  
  • Tar - a carcinogen (a substance that causes cancer)
  • Nicotine - an addictive substance which also narrows blood vessels
  • Carbon monoxide - reduces the oxygen-carrying capacity of the blood

Nicotine

• Nicotine narrows blood vessels leading to an increased blood pressure
• It also increases heart rate
• Both of these effects can cause blood clots to form in the arteries leading to heart attack or stroke

Carbon monoxide

• Carbon monoxide binds irreversibly to haemoglobin, reducing the capacity of blood to carry oxygen
• This puts more strain on the breathing system as breathing frequency and depth need to increase in order to get the same amount of oxygen into the blood
• It also puts more strain on the circulatory system to pump the blood faster around the body and increases the risk of coronary heart disease and strokes

Tar

• Tar is a carcinogen and is linked to increased chances of cancerous cells developing in the lungs
• It also contributes to COPD, which occurs when chronic bronchitis and emphysema (two different diseases which are frequently linked to smoking) occur together
• Chronic bronchitis is caused by tar which stimulates goblet cells and mucus glands to enlarge, producing more mucus
  
  • It destroys cilia and mucus (containing dirt, bacteria and viruses) builds up blocking the smallest bronchioles and leading to infections
  • A smoker’s cough is the attempt to move the mucus
• Emphysema develops as a result of frequent infection, phagocytes that enter the lungs release elastase, an enzyme that breaks down the elastic fibres in the alveoli
  
  • This means the alveoli become less elastic and cannot stretch so many burst
  • The breakdown of alveoli reduces the surface area for gas exchange
  • As it progresses, patients become breathless and wheezy - they may need a constant supply of oxygen to stay alive

Question 21

Describe the role of anaerobic respiration in yeast during bread-making.

Answer 21

Yeast, a single celled fungus, can respire anaerobically. It breaks down glucose to alcohol. Bread is made from flour, which is made from grinding seeds from cereal crops. Most bread is made from wheat flour. Contains a lot of starch and protein - in particular, a protein known as gluten. The dough is made from mixing the flour with water and yeast.

Amylase enzymes break down some of the starch into maltose and glucose, which the yeast can use in anaerobic respiration. It produces bubbles of CO2. These get trapped in the dough. The gluten makes the dough stretchy. The CO2 bubbles cause the dough to rise.

Anaerobic respiration also produces alcohol, but when the bread is baked this is broken down. When the bread is baked, the yeast is also killed.

Question 22

Differences between anaerobic and aerobic respiration

Answer 22

Question 23

Describe 2 features of the trachea

Answer 23

• There is a piece of cartilage called the epiglottis, this either closes or opens up to let things into the trachea. It stops food from going into the trachea.
• The trachea has rings of cartilage around it which keep it open.
• Just below the epiglottis is the voice box, which contains vocal chords, the vocal chords can be tightened by muscles so that they make a noise when air passes over them.

Question 24

Why do we end up having to resort to anaerobic respiration while doing exercise?

Answer 24

Because while doing intense exercise, our breathing rate increases (CO2 build up thingy), so then the muscles in our lungs must contract more and our heart must pump more. These movements by these muscles takes up energy in themselves. So as you can see our energy demands can grow quite large, just to get to that extra bit of energy we require anaerobic respiration.

Question 25

What exactly is an oxygen debt?

Answer 25

Lactic acid build up = must be broken down with oxygen in the liver = require more oxygen in order to break down the lactic acid = it is this ‘oxygen debt’ we must repay = that is why often times athletes pant after a race, they are recovering their oxygen debts. The blood carries the lactic acid from the muscles to the liver, where it is converted back to glucose.

Question 26

Revise the paper (physical) flashcards in your biology folder about the heart/lungs (the bio folder in the closet in your room with all the other folders)

Answer 26

ok

Question 27

You HAVE to read B7 in the textbook

Question 28

You HAVE to go through these essential questions slides: https://docs.google.com/presentation/d/1iGrEelEgimb4xGGT2bd2gCRsNtkfRF__hmCxYYZ719c/edit#slide=id.p

And these are the answers to the essential questions: https://docs.google.com/presentation/d/16NL3wmLCn0pJWwmAQqSmsQDlHyK6A5_36hwaIW2Dde0/edit#slide=id.p

Question 29

Describe the circulatory system

Answer 29

a system of blood vessels with a pump and valves to ensure one-way flow of blood. Pump = heart, tubes = vessels

Question 30

Describe double circulation

Answer 30

a low pressure circulation to the lungs and a high pressure circulation to the body tissues and relate these differences to the different functions of the two circuits.

The lungs are very close to the heart, therefore the heart doesn’t need to pump that hard = low pressure.

In order for the heart to send blood into arteries throughout the entire body, it needs to pump really hard = high pressure.

Question 31

Explain the advantage of double circulation.

Answer 31

• Keeps oxygenated and deoxygenated blood separate
• Double circulation gives the ability to create more pressure to pump blood round the whole body system
• There is a greater flow of blood to the tissues.
• It is more efficient
• As blood travels it loses pressure, through double circulation this pressure is “re-installed”.
• This allows for more efficient supply of oxygen to the body, which is very important for respiration

Question 32

Describe the functioning of the heart

Answer 32

The contraction of muscles of the atria and ventricles and the action of the valves, in order to pump blood throughout the correct parts of the blood.

Question 33

Name the main blood vessels to and from the:

• heart
• lungs
• kidney

Answer 33

ー heart, limited to vena cava, aorta, pulmonary artery and pulmonary vein

ー lungs, limited to the pulmonary artery and pulmonary vein

ー kidney, limited to the renal artery and renal vein.

• Liver, limited to the hepatic artery, portal vein, and hepatic vein

Question 34

Investigate and state the effect of physical activity on pulse rate.

Answer 34

Increases pulse rate.

A pulse is caused by the expansion and relaxation of an artery, caused by the heart pushing blood through it.

The rate at which the heart beats is controlled by a patch of muscle in the right atrium called the pacemaker. The pacemaker sends electric signals through the walls of the heart at regular intervals, causing the muscles to contract.

During exercise there is an increase of CO2 levels in the blood, lowering the pH of the blood. Receptor cells in the brain sense this drop in pH and send nerve impulses more frequently to the pace maker to make the heart contract more.

Question 35

Describe coronary heart disease (CHD) in terms of the blockage of coronary arteries and state the possible risk factors as diet, stress, smoking, genetic predisposition, age and gender (extra point: obesity).

Answer 35

See page 80 of the textbook for diagrams.

Coronary arteries are the blood vessels on the outside of the heart. These arteries supply blood to the heart muscles.

The blood that is in the heart can’t penetrate through its thick walls to get to the muscles and all, thats why these additional arteries are needed.

1. Eating a diet high in salt, saturated fats (fats from animals), trans fat (from meat and mil fat) increases cholesterol levels, which increases the buildup of fatty plaques.
2. The hormone cortisol is released in response to stress. Hormones released due to stress can increase blood pressure, causing blockages.
3. Nicotine in cigarettes will cause blood vessels to become narrower, increasing blood pressure, which will cause the build up of fat globules. If this occurs in the coronary artery this will cause CHD.
4. Genetic predisposition just means you have genes that make you more likely to have the disease. Studies show that people who have families with a history of CHD are more likely to get it.
5. Aging can cause changes in the heart and blood vessels that may increase a person’s risk of developing cardiovascular disease.
6. There is a higher CHD risk in men than women.

Question 36

What is Coronary Heart Disease (CHD)?

Answer 36

• The heart is made of muscle cells that need their own supply of blood to deliver oxygen, glucose and other nutrients and remove carbon dioxide and other waste products
• The blood is supplied by the coronary arteries
• If a coronary artery becomes partially or completely blocked by fatty deposits called ‘plaques’ (mainly formed from cholesterol), the arteries are not as elastic as they should be and therefore cannot stretch to accommodate the blood which is being forced through them - leading to coronary heart disease
• Partial blockage of the coronary arteries creates a restricted blood flow to the cardiac muscle cells and results in severe chest pains called angina
• Complete blockage means cells in that area of the heart will not be able to respire and can no longer contract, leading to a heart attack

Question 37

What muscle is responsible for the pumping motion of the heart

Answer 37

Cardiac muscle

Question 38

Explain the effect of physical activity on heart rate.

Answer 38

Increases (same reasoning as pulse rate)

Question 39

Describe the structure and functions of arteries, veins and capillaries.

Answer 39

read pages 82-83 of textbook

MEMORISE THIS TABLE:

https://drive.google.com/drive/u/0/folders/13d2mTcY9fqOAzYTy3jpkSm6KfzRjRDoG

Question 40

List the components of blood as

Answer 40

red blood cells, white blood cells, platelets and plasma.

Question 41

Explain everything you need to know about red blood cells

Answer 41

• made in the bone marrow of some bones
• They are produced very rapidly. RBCs need to be produced really quickly because they dont live for very long, one reason they don’t live long is because they don’t have a nucleus.
• They are red because they contain the pigment haemoglobin
• Haemoglobin is a protein, it contains iron. Iron readily combines with oxygen where the gas is in good supply, and gives it up where it is in weak supply. It carries oxygen.
• Lack of nucleus = more space for haemoglobin
• Biconcave shape = higher surface area to volume ratio to increase rate of diffusion of oxygen into and out of the cell
• Very small size = enables it to squeeze through tiny capillaries so that oxygen can be taken very close to every cell in the body.

Question 42

Identify red and white blood cells, as seen under the light microscope, on prepared slides and in diagrams and photomicrographs.

Answer 42

Question 43

Explain everything you need to know about the components of plasma

Answer 43

Question 44

Summarise everything you need to know about the components of blood

Answer 44

Question 45

State the functions of the following components of blood:

ー red blood cells

ー white blood cells

ー platelets

ー plasma

Answer 45

ー red blood cells in transporting oxygen, including the role of haemoglobin

ー white blood cells in phagocytosis and antibody production

ー platelets in clotting (details are not required)

ー plasma in the transport of blood cells, ions, soluble nutrients, hormones and carbon dioxide.

Question 46

Explain everything you need to know about platelets

Answer 46

• Platelets are small fragments of cells with no nucleus
• They are made in the red bone marrow
• They are involved in blood clotting
• Blood clotting stops pathogens getting into the body through breaks in the skin
• It is also an important process that prevents excessive bleeding when a blood vessel is injured
• Blood clotting normally occurs when there is damage to a blood vessel. Platelets immediately begin to adhere to the cut edges of the vessel and release chemicals to attract even more platelets. A platelet plug is formed, and the external bleeding stops

Question 47

Explain everything you need to know about white blood cells and the immune system

Answer 47

Link: https://www.youtube.com/watch?v=63XExOKWrqg

Link (white blood cells specifically, VERY GOOD): https://www.youtube.com/watch?v=bGKsGEByr0w