Unit 1 Section 4: The gaseous Exchange System

Question 1

gaseous exchange system in mammals is based around

Answer 1

the lungs

Question 2

basic structure of gaseous exchange system

Answer 2

• Air enters the Trachea (windpipe
• Trachea splits into two bronchi (One bronchus to each lung)
• Each bronchus branches off into smaller tubes called bronchioles
• On the end of Bronchioles are air sacs called alveoli (where gases are exchanged
• in order for this system to work the ribcage, intercostal muscles and diaphragm must work together to ove air in and out

Question 3

Alveoli

Answer 3

• form the gaseous exchange Surface
• arranged in bunches on the end of Bronchioles
• surrounded by capillaries giving each alveolus its own blood supply
• made from a single layer of thin, flat cells called alveolar epithelium.
• Capillary walls made from capillary Endothelium (still a type of epithelium)
• alveoli walls contain Elastic Fibres to help the alveoli return to their normal shape after inhaling/exhaling air.

Question 4

Gas exchange in the alveoli

Answer 4

*oxygen difuses out of alveoli across epithelium into haemoglobin in the blood
*Carbon Dioxide difuses into the alveoli crossing endothelium from the blood
It is then breathed out

Question 5

most exchange surfaces have 2 things in common…

Answer 5

• Large surface area to increase the rate of diffusion

* Thin providing a short diffusion pathway which increases the rate of difusion

Question 6

Lung adaptions

Answer 6

• Many Alveoli increase surface area
• Alveolar epithelium and Capillary endothelium are only 1 cell thick
• Alveoli have a good blood supply (constant exchange of CO2 and Oxygen) maintaining the concentration gradient
• Diaphragm and intercostal muscles involved in ventilation ( keeps high concentration gradient)

Question 7

Goblet Cells

Answer 7

*secrete mucus - which traps microorganisms and dust particles in the inhaled air (bronchus/Trachea/Bronchiole)

Question 8

Cilia

Answer 8

*hair-like structures on the suface of epithelial cells.
*beats mucus
*moving mucus and trapped microorganisms towards the throught where it is swallowed.
(Bronchus/Trachea/Bronchiole)

Question 9

Elastic Fibres

Answer 9

*breathing in inflates lungs and Fibre stretch
*Fibres recoil to help puch the air out when exhaling
(Bronchus/Trachea/Bronchiole/Alveolus)

Question 10

Smooth muscle

Answer 10

*allows control of airway diameter
*Muscles Relax making the tubes wider meaning less resistance to air flow (during exercise)
(Bronchus/Trachea/Bronchiole)

Question 11

Cartillage

Answer 11

*Provides Support
*Strong & Flexible
*Prevents collapsing when breathing in and the pressure drops
(Bronchus/Trachea)

Question 12

Distribution of features: Trachea

Answer 12

• Large C-Shaped Cartilage pieces
• Smooth muscle
• Elastic Fibres
• Goblet Cells
• Ciliated Epithelium

Question 13

Distribution of features: Bronchi

Answer 13

• small Pieces of cartilage
• Smooth muscle
• Elastic Fibres
• Goblet Cells
• Ciliated Epithelium

Question 14

Distribution of features: Larger Bronchiole

Answer 14

• No Cartilage
• Smooth muscle
• elastic Fibres
• Goblet Cells
• Ciliated Epithelium

Question 15

Distribution of features: Small Bronchiole

Answer 15

• No Cartilage
• Smooth muscle
• elastic Fibres
• No Goblet Cells
• Ciliated Epithelium

Question 16

Distribution of features: Smallest Bronchiole

Answer 16

• No Cartilage
• NoSmooth muscle
• elastic Fibres
• No Goblet Cells
• No Cilia

Question 17

Distribution of features: Alveoli

Answer 17

• No Cartilage
• NoSmooth muscle
• elastic Fibres
• No Goblet Cells
• No Cilia