2.46-2.50 gas exchange

What is A and function

Nasal cavity - sense of smell, filtering out foreign particles, moistening air we breath in

Name H and function

Bronchus - large tubes branching off from trachea (one per lung)

Name I and function

Bronchiole - bronchi split into smaller tubes called bronchioles connected to alveoli

Name J and function

Alveoli - tiny air sacs where gas exchange takes place

What is B and function

Pleural cavity - the fluid filled space between pleural membranes which reduces friction and allows the lungs to move freely

Name C and function

Intercostal muscle - muscles between ribs which control movement

What is D and function

Ribs - protects the lungs

What is E and function

Diaphragm - large sheet of muscle that stretches across chest under rib cage, causes chest to expand during inhalation

What is G

Lungs- gas exchange

Describe the contraction of the diaphragm when inhaling and exhaling

I- contract

E- relax

Direction of rib movement during inhaling and exhaling

I- upward and outward

E- downward and inward

External intercostal muscle contraction during inhalation and exhalation

I- contract

E- relax

Internal intercostal muscles contraction during inhalation and exhalation

I- contract

E- contract (only when exhalation is forced)

Lung volume during exhalation and inhalation

I- increase

E- decrease

Lung pressure during inhalation and exhalation

I- decreases (lower than atmospheric pressure)

E- increases (higher than atmospheric pressure)

What is a cavity

A space/chamber

How are alveoli adapted for gas exchange by diffusion between air in the lungs and blood in capillaries?

• many rounded alveolar sacs- large surface area to volume ration

• Thin, single layers of cells to minimise diffusion distance

• Ventilation maintains high level of oxygen and low levels of CO2 - steep concentration gradient

What harmful chemicals are in cigarettes and effects of them?

Nicotine: narrows blood vessels, increases heart rate - increased blood pressure - leads to blood clots in arteries - can result in heart attack or stroke

Carbon monoxide: binds to haemoglobin- reducing capacity of blood to carry oxygen, puts more strain on breathing system - circulatory system needs to pump blood faster - raising blood pressure and increasing risk of coronary heart disease and stroke

Tar: is a carcinogen - lung cancer, contributes to COPD (chronic bronchitis and emphysema together)

Explain how smoking causes chronic bronchitis

• Tar stimulates goblet cells and mucus glands to enlarge and produce more mucus

• blocking the bronchioles and leading to infections and damaging the cilia (preventing them removing the mucus)

• when a smoker coughs - attempt to remove mucus

Explain how smoking causes emphysema

• it is the result of frequent infection (from the build up of mucus)

• The phagocytes that enter the lungs release elastase (enzyme that breaks elastic fibres in alveoli)

• Alveoli is less elastic and cannot stretch - many burst- reduces surface area for gas exchange

• Patients become breathless and wheezy - may need constant supply of oxygen