Breathing and Gas exchange

What is respiration?

• chemical reactions that break down nutrient molecules in living cells to release energy

Why do we need energy?

• for life processes

• active transport

• cell division

• protein synthesis

• muscle contraction

Where does respiration occur?

• MITOCHONDRIA

• release of energy from food

• occurs in every living cell

• in eukaryotic cells the main reactions occur in the mitochondria

What does respiration produce and where is it stored?

• produces energy stored in glucose

• stores it in ATP

• Energy in ATP used by the cell to carry out all its activities

What are the products of respiration?

• Carbon dioxide

  • limewater turns cloudy in presence of CO2

• heat

  • its an exothermic reaction

  • rise in temperature

• Water

• energy

What is the equation for aerobic respiration

What are examples of anaerobic respiration?

• yeast causes bread to rise

• yeast producing ethanol in beer production

• animals carrying out short bursts of exercise

• plant roots in waterlogged soils

What is the equation for anaerobic respiration in animals

What are the disadvantages of anaerobic respiration?

• less ATP is produced for every molecule of glucose

• lactic acid is toxic + can result in fatigue and muscle cramps

• Oxygen debt

  • after anaerobic respiration has taken place

  • lactic acid must be broken down

  • which requires extra oxygen

What is the anaerobic respiration equation in plants + yeast

Compare aerobic + anaerobic respiration

compare energy supplied for aerobic + anaerobic on a graph

How can CO2 be detected?

• using limewater

  • turns cloudy in presence of CO2

• using hydrogen carbonate indicator

  • changes color depending on level of CO2 in surrounding air

What is the scale of hydrogen carbonate indicator?

• yellow = high level

• red = normal/atmospheric levels

• purple = low levels

what is a respirometer?

• a setup which allows us to investigate respiration

What is the method for investigating respiration

• Measure out 10 cm³ of hydrogencarbonate indicator into 3 boiling tubes

• Put in a layer of cotton wool

• Place 10 germinating seeds in tube A

• Place 10 boiled/dead seeds in tube B

• Place 10 glass beads in tube C

• Seal each tube with a rubber bung

• After 3 hours, observe the colour of the indicator

What are the results?

What is breathing?

• movement of gases in and out of the lungs

• muscles are involved

• aka ventilation

• inhalation = breathing in

• exhalation = breathing out

• NOT respiration

What is the link between respiration + breathing?

• organisms breathe to obtain oxygen so their cells can aerobically respire

Label

what is the purpose of alveoli?

• air sacs where gas exchange occurs

what are bronchi?

• 2 tubes that trachea splits into

• contains rings of cartilage to keep airways open while breathing

What are bronchioles?

• smaller tubes bronchi split into

• lead into alveoli

what is the diaphragm?

• muscular sheet at bottom of the thorax

• involved in ventilation

what are the intercostal muscles?

• muscles used to move the ribs during ventilation

• 2 sets - internal + external

what is pleural membranes?

• moist membranes between the inside of the thorax + lungs

• provides lubrication to prevent the lungs from sticking

what are the ribs

• bones that surround the lungs

• act as protection + involved in ventilation

what is the trachea?

• windpipe

• passage of air from outside to inside

• contains rings of cartilidge

what is the pleural fluid?

• fills the gap between the pleural membranes (pleural cavity)

What is ventilation?

• breathing in and

• breathing out

• involved:

  • internal + external intercostal muscles

  • diaphragm

What is the process of inhalation?

1. external intercostal muscles contract - moving ribs up + out

2. diaphragm contracts - flattens

3. increases volume of chest

4. decreases pressure below atmospheric pressure

5. air enters lungs

What is the process of exhalation?

1. external intercostal muscles relax

2. intercostal muscles contract - move ribs down + in

3. diaphragm relaxes - dome

4. decreases volume of chest

5. increases pressure below atmospheric pressure

6. air forced out of lungs

What is gas exchange?

• process of oxygen + carbon dioxide moving between the lungs + the blood

• oxygen - diffuses from air → blood

• carbon dioxide - diffuses from blood → air

What is the process of gas exchange throughout the body?

1. oxygenated blood is picked up by RBC - oxygenated blood

2. oxygenated blood is pumped around the body to the cells in our tissues

3. cells of the tissues use the oxygen- blood is now deoxygenated

4. tissues produces waste carbon dioxide

5. carbon dioxide is removed from the blood in the lungs

why can small unicellular organisms such as bacteria simply diffuse resources?

• small organisms have a large surface area to volume ratio

• diffusion of resources such as oxygen is therefore very efficient

how do large multicellular organisms with small SA:V get sufficient resources such as oxygen?

• large organisms with small SA:V need specialised exchange surfaces such as lungs to obtain the resources they need

where does gas exchange take place?

• takes place in alveoli

• oxygen diffuses into the blood + carbon dioxide diffuses out of the blood

What makes alveoli efficient for gas exchange?

1. short diffusion path

   • one cell thick alveoli + one cell thick capillaries

   • surface across diffusion occurs is thing → rate is high

2. Large surface area

   • alveoli increase the surface area immensely

3. Large difference in concentration

   • maintained by breathing + a continuous blood flow

   • increase rate of diffusion

4. moist surface

   • moist surfaces allow gases to dissolve + diffuse across the wall more effectively

5. Many of them

   • large surface area

6. well ventilated

   • maintains large concentration gradient - increase rate of diffusion

why does breathing rate increase during exercise?

• during exercise muscle cells respire more to produce ATP for muscle contraction

• oxygen - must be delivered to them more quickly

• waste carbon dioxide must be removed more quickly

• achieved by increasing breathing rate

what is the method of effect of exercise on breathing rate?

• Work out student A's breathing rate at rest

  • Count their number breaths for 15 seconds and multiply by 4

  • Repeat several times to calculate an average

• Student A should then exercise for a set time (at least 4 minutes)

• Immediately after exercising, count the breaths taken in 15 seconds and multiply by 4 to obtain the breathing rate per minute

  • Compare the result to the breathing rate at rest in order to work out the change in breathing rate as a result of exercise

• Repeat this last step every minute after exercise for 5 minutes

• Repeat the process for student B

• Finally, repeat the whole investigation for each student after a period of rest

what are the results?

• Frequency of breathing increases 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 breathing rate remained elevated for a period of time

  • This is because 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 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

Why do people smoke?

• it helps them think

• it relieves stress

• to break the ice when socialising

• to calm down after a fight

• to have a break from work

• to pass time or relieve boredom

What is in cigarettes?

What is nicotine + its effect?

• addictive drug

• affects central nervous system

• increases the heart rate + narrow blood vessels

• causing high blood pressure

• can lead to heart disease

What is carbon monoxide + its effect?

• a poisonous gas that reduces the amount of oxygen that RBC carry around the body

• combines with haemoglobin in RBC preenting oxygen from combining with it

• also causes an increases in heart rate to compensate for the reduced oxygen-carrying capacity of the blood

• can lead to heart disease

What is cilia and mucus purpose?

• cells in the lining of the respiratory tract

• produce sticky mucus to trap dirt + microbes

• cells with tiny hair like parts - cilia

• normally move the mucus out of the lungs

What is tar + its effect?

• brown sticky substance consisting of tiny particles

• formed when tobacco smoke condenses

• deposited in the lungs + coats the surface of the cilia - making them non-funcitonal

• leads to build up of mucus with trapped pathogens

• pathogens in warm + moist airways - leading to infection such as bronchitis

• carcinogenic

• causes cells to mutate + divide uncontrollably - leading to a tumour

what types of cancer does tar lead to?

• lung

• tongue

• bladder

• kidney

• liver

How does smoking affect the skin?

• premature aging + wrinkles

• poor wound healing

how does smoking affect the respiratory system?

• chronic obstructive pulmonary disease

• increased risk of viral + bacterial infection

• increased risk of active tuberculosis

• increased risk of asthma

how does smoking affect the cardiovascular system?

• increased risk of heart failure + stroke

• peripheral vascular disease

how does smoking affect the immune system?

• weakens it

how does smoking affect the teeth?

gum disease

how does smoking affect reproduction?

• infertility in men + women

• paternal germline DNA mutation

• increased risk of sexually transmitted diseases

how does smoking cause diabetes?

• non-insulin dependent diabetes melitus

What is emphysema?

• smoke damages the delicate alveoli

• they lose elasticity

• and the walls break down + fuse back togehter forming large irregular air spaces

• this reduces surface area for gas exchange

• gas exchange becomes very inefficient

• sufferers struggle to carry out even light activities

How does smoking effect pregnancy?

• underweight baby

• heart defects

• decrease lung function

• brain function affected

• death