VentilationLO:

All must label the respiratory system

Most could describe how ventilation occurs

Some could explain how ventilation ensures a steep concentration gradient for gas exchange.

Starter:

1)Read the marking I have done and RESPOND TO IT!

2) Describe how we breathe in and out

TITLE: Photosynthesis - making the links

Objectives:•To know that the lungs are the site of gas exchange in mammals (grade C)•Villi and microvilli allow efficient exchange in the small intestine (grade C/B)•Gas exchange is efficient due to structural adaptations (Grade B/A)•Gas exchange occurs by the process of diffusion (Grade B/A)•The diaphragm separates the thorax from the abdomen

KEY WORDS:

LungsAlveoli/alveolusBlood vesselsCapillariesExchangeDiaphragmIntercostal musclesInternalExternalSurface areaThin layerMonocellularMoistureVilliMicrovilli

Outcomes:

•Label a diagram of the lungs and an alveolus•Active listening – extracting information from alternative sources.

The Respiratory System

-The respiratory system consists of any part of the body that aids breathing.

SIMPLIFIED (check the science)

- The whole process begins with breathing in.

- Air is inhaled through the nose or mouth and air is sucked (is this good science?) down the wind pipe.

-This air travels around the lungs delivering oxygen to the red blood cells and taking carbon dioxide away. The air is then pushed back up the wind pipe and out through the mouth and nose.

Task

• Check your labelling of the diagram of the lungs.

• Video: Make notes on these videos

• BBC - Learning Zone Class Clips - Gaseous exchange in the lungs - Science Video

• http://www.dnatube.com/video/2903/How-does-gas-exchange-occurs-in-the-lungs-3D-animation

Words: abdomen, diaphragm, ribs, intercostal muscles, thorax, trachea, bronchi, lung, heart, alveoli, nose, mouth

Words: abdomen, diaphragm, ribs, intercostal muscles, thorax, trachea, bronchi, lung, heart, alveoli, nose, mouth

How does ventilation happen?

• Ventilation requires pressure changes to occur in the lungs, so that air can be forced in and out of the alveoli.

• The pressure changes are brought about by the movement of two sets of muscles....

How does ventilation happen?

1. The diaphragm, which is a sheet of muscle that separates the thorax (chest) from the abdomen moves

2. The intercostal muscles which lie between the ribs. There are two sets of intercostal muscles....

The intercostal muscles – an antagonistic pair

• The internal intercostal muscles, whose contraction leads to exhalation.

• The external intercostal muscles, whose contraction leads to inhalation.

INHALATION and EXHALATION

Ventilation Flow diagram

Intercostal muscles contract pulling your ribs up and out. Diaphragm also flattens.

Volume of thorax increases

Therefore, pressure in thorax decreases

Air enters the lungs

Task – 10 minutes• Draw a table like the one below....

• Fill in what happens to the things on the left (i.e diaphragm, air pressure in lungs...) during inspiration and expiration.

Inhalation Exhalation

External intercostal muscles

Internal intercostal muscles

Diaphragm

Air pressure in lungs

Air movement along pressure gradient

Lung volume

Answers, please!

Inhalation Exhalation

External intercostal muscles

Contract – pulling ribs upwards and outwards.

Relax – permitting rib cage to move downwards and inwards.

Internal intercostal muscles

Are relaxed. Contract – moving the ribs downwards and decreasing the volume of the thorax.

Diaphragm Contracts – moves downwards from domed position.

Relaxes – elasticity returns to domed position,

Air pressure in lungs Decreases Increases

Air movement along pressure gradient

Into lungs Out of lungs

Lung volume Increases Decreases

Describe the relationship between these two columns

Air in the lungs/GASEOUS EXCHANGE

The inhaled air travels down the trachea into the lungs via a network of tubes. Q – What are these tubes called?

The air then circulates inside the millions of alveoli. ALVEOLI are small air sacs that are each coated in a network of very small blood vessels which allows the blood to absorb oxygen that diffuses across the membranes Q use terms to describe how this occurs

Carbon dioxide also diffuses across from the blood into the alveoli. Q Use suitable terms to describe how.

GASEOUS EXCHANGE

6 mark Question

• In this question you will be assessed on the quality of written communication including spelling, punctuation and grammar.

• Explain in detail how a steep concentration gradient is maintained in the lungs to ensure rapid gas exchange.

Plenary Glossary

• What words can you think of that relate to this topic?

• Discuss

• Now produce a glossary of these terms which must be written in your own words.