Respiration and Gas Exchange

Why do we Breathe?Why do we Breathe?

• Breathing is needed to provide oxygen for organisms.

• Aerobic respiration produces much more energy than anaerobic.

• Needs a gas exchange surface for this to happen.

Respiration & Gas ExchangeRespiration & Gas ExchangeKey Words:

Thorax

Breathing

Diaphragm

Intercostal muscles

Gas exchange

Objectives:

Discuss the mechanics of breathing

Outcomes:

-Define breathing and why we breathe.-Identify the parts of the breathing system & name their functions.-Explain how breathing happens in terms of pressure & muscles.-State the difference between breathed in & expired air.

Breathing is the taking of air in and out of the lungs.

Gas exchange is the intake of oxygen and the excretion of carbon dioxide at the lung surface. Oxygen moves into the blood and carbon dioxide moves out of the blood.

Cell respiration is the process that releases energy from the food. It happens in all cells.

Can you explain how these 3 processes all depend on each other?

Bronchi

Lung

Bronchiole

Mucus and hairs trap pathogens (germs) and dust.

They must be kept out of the delicate lung tissue.

Sinuses are large blood-filled spaces that warm the air before it enters the lung.

Epiglottis

A flap of tissue called the epiglottis stops food or water going down the windpipe (trachea) into the lung.

Larynx – Vocal Chords

Vibrations across the larynx produces sounds.

Trachea and BronchiLarynx

The windpipe is called the trachea.

Trachea is protected and supported by rings of cartilage.

Bronchi also have these rings.

Trachea are cleaned by cilia which beat a layer of mucus up out of the trachea.

The mucus is sticky so it traps dust, dirt and pathogens.

Bronchioles

• Bronchi branch into many smaller bronchioles.

• Bronchioles are not supported with cartilage.

• Smooth muscles adjust the size of bronchioles (dilate).

Cartilage at end of ribs allows them to move during breathing.

The ribs protect the heart and lungs.

BreathingBreathing is due to pressure changes in the lung.

This is due to the action of the diaphragm and intercostal (rib) muscles.

Lungs sit in the pleural cavity which is airtight.

Inhalation happens because the diaphragm contracts and the ribs expand (lift up). This increases volume so reduces pressure in the lungs and air rushes in. Exhalation is the opposite.

Breathing Out Breathing In

External Intercostal Muscles

• Rib muscles are arranged in two layers: internal and external intercostal muscles.

• External intercostal muscles contract to pull the ribcage upwards and outwards.

Internal Intercostal Muscles

• Internal intercostal muscles contract to pull the ribs closer together and pull the ribcage down.

• This produces exhalation.

• Internal and external muscles work against each other.

Respiration & Gas ExchangeRespiration & Gas ExchangeKey Words:

Aerobic

Anaerobic

Respiration

Symbol equation

Balanced equation

Respire

Lactic Acid

How does the Body use Energy?How does the Body use Energy?

• To move around• To make the heart beat and to move blood

around the body• To speak• To keep our bodies warm• To reproduce• To grow• To excrete and to feed• To send nerve messages around the body

Where do we get Energy Where do we get Energy from?from?

• Energy comes from food

• Food is broken down in cells in a process called respiration

• This breakdown of food releases energy

• Enzymes control the breakdown

RespirationRespiration

• Respiration is the release of energy from food substances in living cells.

• Aerobic respiration requires oxygen and releases more energy than anaerobic respiration.

• Sugar + oxygen carbon dioxide + water + energy

• CC66HH1212OO66 + O + O22 CO CO22 + H + H22O + energyO + energy

Anaerobic Respiration

• Anaerobic means without oxygen

• Muscles can become low in oxygen under stress

• Makes less energy than aerobic but continues to release energy without O2

• They produce lactic acid which causes muscle fatigue:

• Glucose lactic acid

• CC66HH1212OO66 2C 2C33HH66OO33

Lactic AcidLactic Acid

• Lactic acid (lactate) is poisonous and builds up in the muscles during anaerobic exercise

• Lactic acid is sent to the liver where it must be broken down

• This breakdown requires oxygen and is called the oxygen debt

• This happens when oxygen becomes available again

ComparisonComparison

Aerobic Respiration Anaerobic Respiration

1. Oxygen is used 1. Does not use oxygen

2. A lot of energy is released

2. Less energy is released

4. All multicellular organisms

4. Unicellular plants and muscles for short periods

Gas ExchangeGas ExchangeKey Words:

Breathing

Alveolus

Diaphragm

Trachea

Addiction

Emphysema

Objectives:

Gas exchange, smoking & asthma

Outcomes:

D:-Define gas exchange

A-C:

-Identify the parts of the body involved in gas exchange-Explain how gas exchange occurs-Explain the health effects of smoking-Understand emphysema

Composition of Air

Percentage of the gas present in

Gas Air breathed in Air breathed out

Carbon dioxide

0.04 4

Oxygen 21 17

Nitrogen 78 78

Water vapour low high

Artificial Breathing

• There is still 17% of oxygen in the air we exhale.

• This makes it possible to breathe for someone who is unable.

Gas ExchangeGas Exchange

• Small animals exchange gases across their surface by diffusion.

• Larger organisms have too small a surface area to volume ratio to supply oxygen by diffusion.

• They have a lung or gills for gas exchange• Need a concentration gradient in the lung for

gas exchange by diffusion.

Gas Exchange SurfacesGas Exchange Surfaces

To be efficient a gas exchange surface

must:• have a large surface area.• be supplied with lots of blood vessels to take

gases away – maintains concentration gradient.• be moist so gases can dissolve for diffusion.• be very thin so diffusion across the membrane is

easy.• have a concentration gradient due to movement

of air and its use

Alveolus

Bronchioles lead to air sacs called alveoli. They are the sites of gas exchange.

Alveoli provide an efficient surface for gas exchange because:

1.They are thin for rapid diffusion.

2.They are moist for diffusion of gases.

3.They are surrounded by lots of blood vessels (capillaries) to carry oxygen away and maintain the gradient.

4.They have a very large surface area.

Testing for Carbon Dioxide

• Carbon dioxide can be tested for with limewater.

• A clear solution of limewater turns cloudy when CO2 is bubbled through it.

Breathing Rate with Exercise

• Exercise means cells need more energy from respiration.

• This means more oxygen is needed for respiration.

• This means we breathe faster.

Exercise Builds up Toxins

• Exercise produces carbon dioxide so CO2 increases in concentration.

• CO2 makes blood acidic so pH of blood drops.

• This drop in pH causes the breathing rate to increase to get rid of the CO2.

• At the same time O2 is breathed in as it is exchanged for CO2.

Smoking

• Smoking increases the risks of heart disease many times.

Tobacco Smoke

• Burning tobacco releases carbon monoxide which is poisonous – it stops haemoglobin transporting oxygen.

• Nicotine increases heart rate and blood pressure and it is carcinogenic – causes cancer. It is used in some insecticides because it is poisonous. It is addictive.

Smoking and the Heart

• Muscles in the heart need a steady supply of oxygen-rich blood to work efficiently.

• Smoking reduces the amount of oxygen the blood can carry by up to 30%.

• Over time, smoking damages the heart by overworking it and this disease is called coronary heart disease (CHD).

• Even light smokers have a higher risk of CHD than non-smokers.

Strokes

• Smokers are much more likely to have a stroke than non-smokers. People who smoke more than 20 cigarettes a day are four times more likely to suffer a stroke than a non-smoker.

• Smoke particles irritate the air passages leading to inflammation, mucus production, coughing and emphysema.

• Tar is a carcinogen also and it damages the cilia causing bronchitis.

The tar taken in by a smoker in one year.

Addiction

• It all starts in the brain.

• Nicotine reaches the brain within 10 seconds of inhaling smoke from a cigarette.

• The nicotine attaches itself onto the brain’s working cells called neurons.

• These cells send messages to a different part of the brain to release stimulants.

• They make the smoker ‘feel’ more relaxed (although actually they’re not because their heart is beating even faster).

• These feelings don’t last long and over time, a person needs to smoke more and more cigarettes to get these feelings back.

• When the nicotine levels start to drop, the smoker starts to feel like they need another cigarette. These are cravings, and the stronger the cravings get, the more stressed the person feels.

• When the person finally has another cigarette, the whole process starts again.

Passive Smoking

• Passive smoking affects everyone around a smoker.

• If a baby’s parents smoke 20 cigarettes a day that baby will have smoked 80 cigarettes by the time it is one year old!

Emphysema

If bronchioles fill with fluid the alveoli can swell up and explode. Alveoli have reduced surface area. Smoking causes.

AsthmaBronchioles fill with mucus and muscles fail to dilate properly.