Biology 2017-2018 Name: Noble efforts change lives. Excellence. Tenacity. Community. Reflection.

Topic #6: Human Physiology6.4: Gas Exchange

Skeleton NotesSyllabus Statement Guidance6.4.U1 Ventilation maintains

concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries.

6.4.U2 Type I pneumocytes are extremely thin alveolar cells that are adapted to carry out gas exchange.

6.4.U3 Type II pneumocytes secrete a solution containing surfactant that creates a moist surface inside the alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension.

6.4.U4 Air is carried to the lungs in the trachea and bronchi and then to the alveoli in bronchioles.

Students should be able to draw a diagram to show the structure of an alveolus and an adjacent capillary.

6.4.U5 Muscle contractions cause the pressure changes inside the thorax that force air in and out of the lungs to ventilate them.

6.4.U6 Different muscles are required for inspiration and expiration because muscles only do work when they contract.

6.4.A1 Causes and consequences of lung cancer.

6.4.A2 Causes and consequences of emphysema.

6.4.A3 External and internal intercostal muscles, and diaphragm and abdominal muscles as examples of antagonistic muscle action.

6.4.S1 Monitoring of ventilation in humans at rest and after mild and vigorous exercise. (Practical 6)

Recommended resources: Allott, Andrew. Biology: Course Companion. S.I.: Oxford UP, 2014. Print.

Breathing is NOT respiration!

Ventilation: Movement of air into and out of the lung in two stages:

a.

b.

This is controlled by movement of the diaphragm and ribcage.

Gas Exchange:

Cell Respiration: This is production of ATP at the cellular level.

How do small organisms ventilate? Provide examples

How do larger organisms ventilate? Provide examples

6.4.U1 – Ventilation maintains concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries.

Why do we need ventilation systems?

Where are the ‘moist membranes’ located?

McGraw Hill Video (use link on the webpage or enter on chromebook) http://highered.mheducation.com/sites/0072495855/student_view0/chapter25/animation__gas_exchange_during_respiration.html

6.4.U4: Air is carried to the lungs in the trachea and bronchi and then to the alveoli in bronchioles.

PRACTICE: Add labels to the image. Produce a flow chart to show the passage of air into the lungs.

6.4.A3: External and internal intercostal muscles and diaphragm and abdominal muscles as examples of antagonistic muscle action

AND

6.4.U5: Muscle contractions cause the pressure changes inside the thorax that force air in and out of the lungs to ventilate them.

Summary of the mechanics of ventilation:

Inspiration Expiration

pressure changevolume changeribcage movementexternal intercostal muscles

internal intercostal muscles

diaphragmabdominal muscles

diagrams

6.4.U6: Different muscles are required for inspiration and expiration because muscles only do work when they contract.

PRACTICE: Which muscles work together antagonistically? Explain this process.

6.4.A3: External and internal intercostal muscles and diaphragm and abdominal muscles as examples of antagonistic muscle action. AND6.4.U5: Muscle contractions cause the pressure changes inside the thorax that force air in and out of the lungs.

Ventilation involves two pairs of opposite movement that change the volume and therefore the pressure inside the thorax:

Structure Inspiration Expiration

Diaphragm Moves downward and flattens Moves upwards and becomes more domed

Ribcage Moves upwards and outwards Moves downwards and inwards.

Antagonistics pairs of muscles are needed to cause these movements

Inspiration Expiration

Volume and pressure changes

Volume inside thorax increases and consequently the pressure decreases

The volume inside thorax decreases and consequently the pressure increases.

Inspiration Expiration

Movement of the diaphragm

Diaphragm The diaphragm contracts so it moves downwards and pushes the abdomen wall out

The diaphragm relaxes so it can be pushed upwards into a more domed shape

Abdominal wall muscles

Muscles in the abdomen wall relax allowing pressure from the diaphragm to push it out

Muscle in the abdomen wall contact pushing the abdominal organs and diaphragm upwards.

Movement of ribcage

External intercostal muscles

External intercostal muscles contract, pulling the ribcage upwards and outwards

The external intercostal muscles relax and are pulled back to their elongated state.

Internal intercostal muscles

The internal intercostal muscles relax and are pulled back into their elongated state

The internal intercostal muscles contract pulling the ribcage inwards and downwards.

6.4.U2: Type I pneumocytes are extremely thin alveolar cells that are adapted to carry out gas exchange. AND6.4.U3: Type II pneumocytes secrete a solution containing surfactant that creates a moist surface inside the alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension.

Type I pneumocytes Type II pneumocytes

How many layers? What does it secrete?

Thick or thin? What does it moisten?

Why does it need to be thin? What is the fluid needed for?

Why does it need to be permeable? What is the purpose of the SURFACTANT?

Other general information:● Wall of each alveolus consists of a single

layer of cells called the EPITHELIUM● Most cells in the epithelium are Type I

pneumocytes● Flattened cells, thickness of only about

0.15 µm of cytoplasm● Wall of adjacent capillaries also single

layer of very thin cells● Air in alveolus and blood are less than

0.5 µm apart.

What can Type II pneumocytes divide into? Why?

6.4.A2: Causes and consequences of emphysema.

What is the main cause of emphysema? What other factors can impact emphysema?

●

●

●

● All which cause an

PROTEASE is released by the leukocytes (white blood cells) and inflamed lung tissue. What does it do?

●

● Example:

● Results in:

● Results in:

● Breaks down:

What are the consequences?

● SA: Volume

● Causes

● When combined with reduced blood supply =

● __________________ blood oxygen levels.

Diagrams:

Symptoms of Emphysema?

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●

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●

Review – 1.6.U6: Mutagens, oncogenes, and metastasis are involved in the development of primary and secondary tumors.

Tumors are abnormal growth of tissue that develop at any stage of life in any part of the body. A cancer is a malignant tumor and is named after the part of the body where the cancer (primary tumor) first develops. Use the links on the website to find out:

most common types of cancer what causes cancer and associated risk factors how cancer can be treated

6.4.A1: Causes and consequences of lung cancer.

Answer the following questions:

- What are the main causes of cancer?

- What are the symptoms of lung cancer?