The respiratory systemThe respiratory system

Lung structure and function

Respiration Respiration VCE Unit 1 BiologyVCE Unit 1 Biology

Structure of the respiratory system?Structure of the respiratory system?

1.1. Air enters the Air enters the nose/mouthnose/mouth

2.2. Air travels _______Air travels _______

3.3. Air reaches major Air reaches major bronchibronchi

4.4. Air then gets fed Air then gets fed through a number through a number of smaller tubes of smaller tubes called the called the __________________________

5.5. Air eventually Air eventually reaches the _____reaches the _____

Functions of the upper airwayFunctions of the upper airway

• Nose, larynx and trachea

• Warms and ____________ inspired air

• Traps & eliminates foreign particles – involved in coughing

• Not involved in __________________

Functions of the lower airwayFunctions of the lower airway

• From the ________to __________

• Secrete mucus to catch foreign material

• Cilia (hair-like structure on top of cell) can beat to push mucus back up airways where it can be coughed out

The alveoli are the site of gas exchangeThe alveoli are the site of gas exchange

• There are approximately __ _____ alveoli in our lungs

• The look a bit like a bunch of grapes

• If you spread out each of these alveoli, they would take up an entire ________ ________!

Alveoli are surrounded by capillariesAlveoli are surrounded by capillaries

Why do you think this is the case?

Alveoli are surrounded by capillariesAlveoli are surrounded by capillaries

Answer: • Capillaries ensure that the breathed “air” is brought into close proximity to the “pulmonary” blood.• This allows _________ ____ _________ _________ ___ ___ ____ ____ _______.

Thin tissue separates blood from alveoliThin tissue separates blood from alveoli

• ________ ___ _______ walls are thin, permitting rapid _________ of gases.

• Each RBC is only in lung capillary for 1 second

(RBC)

Answer the following in your workbooksAnswer the following in your workbooks

• Where does gas exchange occur?Where does gas exchange occur?

• What structures does air pass through to get to the site of What structures does air pass through to get to the site of gas exchange?gas exchange?

• What would happen if there was a thick gap between the What would happen if there was a thick gap between the alveoli and the capillaries?alveoli and the capillaries?

• Name a disease where the gap between the alveoli and Name a disease where the gap between the alveoli and capillary is increased.capillary is increased.

• What respiratory structure is affected in bronchitis and What respiratory structure is affected in bronchitis and asthma?asthma?

Questions to be finished for homework and handed in next Questions to be finished for homework and handed in next classclass

Respiratory muscles allow us to inspireRespiratory muscles allow us to inspire

• There are There are two phasestwo phases in respiration in respiration (breathing): ________ ___ ________.(breathing): ________ ___ ________.

• Inspiration Inspiration (breathing in)(breathing in) allows gas to allows gas to enter the lungenter the lung

• ExpirationExpiration (breathing out) allows gas to (breathing out) allows gas to exit the lungexit the lung

The process of inspirationThe process of inspiration

• Inspiration relies on the _________ and the rib Inspiration relies on the _________ and the rib musclesmuscles

• The diaphragm is _ ____ ___ _____ that The diaphragm is _ ____ ___ _____ that separates the chest cavity from the abdomenseparates the chest cavity from the abdomen

• During inspiration, the diaphragm and rib muscles During inspiration, the diaphragm and rib muscles ______. This increases the size of the chest ______. This increases the size of the chest cavity.cavity.

• The increase in chest cavity size _______ The increase in chest cavity size _______ _______ inside the chest. _______ inside the chest.

• As a result, the lungs are expanded and air is As a result, the lungs are expanded and air is sucked in (just like a ______!)sucked in (just like a ______!)

The process of expirationThe process of expiration

• _______ occurs when the _____ ___________ occurs when the _____ ____• The lungs undergo a process called ______ which The lungs undergo a process called ______ which

allows them to return to their original sizeallows them to return to their original size• Recoil of the lungs occurs because the lungs are Recoil of the lungs occurs because the lungs are

very elastic – just like an elastic band! very elastic – just like an elastic band!

Question:Question: what what happens to an elastic happens to an elastic

band after you band after you stretch it?stretch it?

Muscles of Respiration Muscles of Respiration

InspirationInspiration

• Inspiratory muscles Inspiratory muscles act to act to chest chest volumevolume

• Diaphragm - major Diaphragm - major inspiratory muscleinspiratory muscle

• Rib muscles – help Rib muscles – help the diaphragm to the diaphragm to increase chest volumeincrease chest volume

ExpirationExpiration

• The muscles relaxThe muscles relax

• The lungs recoil The lungs recoil because they are because they are elasticelastic

Lung expansion relies on intrapleural pressure.Lung expansion relies on intrapleural pressure.

• How does increasing and How does increasing and decreasing thoracic volume decreasing thoracic volume alter lung volume?alter lung volume?

• The lungs are only attached The lungs are only attached at the hilus!at the hilus!

• Lung expansion following Lung expansion following increased thoracic volumes is increased thoracic volumes is dependent on dependent on _______ _______ __________________

Lung only attached at hilus

What is intrapleural space?What is intrapleural space?

• Each lung is attached to and Each lung is attached to and surrounded by a thin ______ surrounded by a thin ______ called a visceral pleural saccalled a visceral pleural sac

• The inside of the rib cage is also The inside of the rib cage is also covered in a thin membrane covered in a thin membrane called the parietal pleuracalled the parietal pleura

• These two membranes are These two membranes are separated by the a thin layer of separated by the a thin layer of liquid known as the ________ liquid known as the ________ ____________

• Imagine effects of drop of water Imagine effects of drop of water between two glass sheets - between two glass sheets - easy to easy to slide; hard to pull apartslide; hard to pull apart

Intrapleural space (-5cmH2O)

Visceral pleura

Parietal pleura

• The pressure within the intrapleural The pressure within the intrapleural space is negative (like a vacuum). This space is negative (like a vacuum). This ______ ___ _____ _____ even though ______ ___ _____ _____ even though they want to collapse like an elastic they want to collapse like an elastic bandband

• When the chest expands during When the chest expands during inspiration, the intraplueral pressure inspiration, the intraplueral pressure becomes even more negative and becomes even more negative and sucks the lung to the chest wallsucks the lung to the chest wall

• This results in the lungs This results in the lungs ________during inspiration________during inspiration

Intrapleural space

Visceral pleura

Parietal pleura

Why is intrapleural space important?Why is intrapleural space important?

Sheep diaphragmLoss of intrapleural pressure…

Loss of intrapleural pressure Loss of intrapleural pressure

What is in the air we breathe?What is in the air we breathe?

• Atmospheric air contains mostly _______ Atmospheric air contains mostly _______ gas and oxygengas and oxygen

• Nitrogen makes up approximately _____ of Nitrogen makes up approximately _____ of air but is “inert”air but is “inert”

• Oxygen makes up approximately ___ __ __Oxygen makes up approximately ___ __ __

• Not much carbon dioxide is in atmospheric Not much carbon dioxide is in atmospheric air – it only makes up a ____ percentage air – it only makes up a ____ percentage (0.0004%!)(0.0004%!)

• Small amounts of water vapour and other Small amounts of water vapour and other gases are also presentgases are also present

What do our cells need?What do our cells need?

• The cells in our body need ______ to The cells in our body need ______ to survivesurvive

• They use this oxygen in a process called They use this oxygen in a process called __________ to create energy__________ to create energy

• A by-product of metabolism is the A by-product of metabolism is the generation of _______ ______generation of _______ ______

• Carbon dioxide can be _____ if it builds up Carbon dioxide can be _____ if it builds up in the bodyin the body

• Therefore, the lungs need to supply oxygen Therefore, the lungs need to supply oxygen for our cells but remove carbon dioxidefor our cells but remove carbon dioxide

How do the lungs do this?How do the lungs do this?

• Via a process called “___ ________”Via a process called “___ ________”

• Gas exchange does not occur on a 1:1 Gas exchange does not occur on a 1:1 basis (ie 1 molecule of oxygen is not basis (ie 1 molecule of oxygen is not exchanged for every molecule of carbon exchanged for every molecule of carbon dioxide)dioxide)

• Rather the entry of oxygen into the blood Rather the entry of oxygen into the blood and the removal of carbon dioxide occurs and the removal of carbon dioxide occurs according to differences in ________ according to differences in ________ between the alveoli and bloodbetween the alveoli and blood

• That is, it occurs via That is, it occurs via ______________, down a , down a __________ ____________________ __________

What happens then?What happens then?

• Once oxygen diffuses across the alveoli, it Once oxygen diffuses across the alveoli, it enters the blood. enters the blood. Which components of Which components of blood carries oxygen?blood carries oxygen?

• Gases dissolve within the blood. They __ Gases dissolve within the blood. They __ ___ ____ __ _______.___ ____ __ _______. (eg The bends in (eg The bends in diving –diving – what happens when bubbles of gas what happens when bubbles of gas form in the body?)form in the body?)

• The oxygenated blood travels to the heart The oxygenated blood travels to the heart and then around the body to the and then around the body to the tissues/cells.tissues/cells.

Blood goes to tissues and then returns Blood goes to tissues and then returns to the lungto the lung

• The oxygen diffuses down its concentration The oxygen diffuses down its concentration gradient to enter the tissuesgradient to enter the tissues

• Carbon dioxide concentrations are high in Carbon dioxide concentrations are high in the cells.the cells. What do you think happens to the What do you think happens to the carbon dioxide here?carbon dioxide here?

• Blood returning to the lung is deoxygenated. Blood returning to the lung is deoxygenated. What does this mean?What does this mean?

• What happens to this blood at the lungs?What happens to this blood at the lungs?

• What happens to the blood then? What happens to the blood then? Think Think back to your circulation lessons!back to your circulation lessons!

Diffusion of gases at the alveoliDiffusion of gases at the alveoli