chapter 11

Question 1

Describe the features of gas exchange surfaces in humans

Answer 1

Large surface area : for faster diffusion of gases across the surface
Thin walls : Ensure diffusion distances remain short
Good ventilation with air : so that diffusion gradients are maintained
Good blood supply : maintain high concentration gradient so diffusion is faster

Question 2

State the different parts of the breathing system and their functions

Answer 2

Trachea - windpipe connecting mouth and nose to windpipe
Larynx - voice box, helps to make sounds when air passes across
lungs
Bronchi / Bronchus - Branching off trachea
Bronchioles - split from bronchi connected to alveoli
Alveoli - tiny air sacs where gas exchange takes place
Ribs - bone structure that protects internal organs
Diaphragm - At the bottom of the thorax that helps change volume of thorax allows in and exhalation
Intercostal muscles - Between ribs which control movement causing inhalation and exhalation
External and internal intercostal muscles

Question 3

State the function of the cartilage in the trachea

Answer 3

1. to give support , to prevent trachea from collapsing
2. to keep airways open
3. to give flexibility

Question 4

Explain inhalation , exhalation with regards to the ribs, intercoastal muscles and the diaphragm .

Answer 4

Inhalation:
1. External intercostal muscle CONTRACTS
2. internal RELAX
3. Ribcage moves UP & OUT
4. Diaphragm CONTRACTS & moves DOWN
5. Volume of chest INCREASES
6. Pressure of chest DECREASES
7. Air is forced IN to lungs

Exhalation:
1. External intercostal muscle RELAX
2. internal CONTRACTS
3. Ribcage moves DOWN & IN
4. Diaphragm RELAXS & moves UP
5. Volume of chest DECREASES
6. Pressure of chest INCREASES
7. Air is forced OUT of lungs

Question 5

Explain the differences in composition between inspired and expired air

Answer 5

Gas IN OUT
Oxygen 21% 16%

Carbon
dioxide. 0.04% 4%

Water
vapour lower higher. Water evaporates from the moist lining of
alveoli into expired air

Nitrogen 78% 78% Very stable so not used

Temp. lower Higher

Question 6

How can the effect of exercise on breathing be investigated?

Answer 6

1. Measuring number of breath per minute
2. Measuring chest expansion over 5 beats
3. Depth of breath can be measured by a spirometer

Question 7

Explain the link between physical activity and the rat and depth of breathing

Answer 7

1. Frequency and depth of breathing INCREASES during exercise > muscles respire aerobically so need more oxygen and more co2 to be removed

Respiration rates INCREASES, more CO2 produced and enters the blood
Co2 is ACIDIC so it DECREASES the PH of blood, denaturing ENZYMES

Blood flows through brains and the INCREASE carbon dioxide concentration stimulates RECEPTOR CELLS IN BRAIN
These send IMPULSES to MUSCLES of the LUNGS , causing them to CONTRACT and RELAX more frequently.

This causes frequency and depth of breathing to increase to EXHALE MORE CO2 so that CO2 concentration can return to normal

Question 8

Describe the role of goblet cells, mucus and cilated cells in protecting the breathing system

Answer 8

1. passage of lungs lined with ciliated epithelial cells
   2.Cilia beat and push mucus up the passages towards nose and throat to be removed
2. Mucus is made by GOBLET CELLS
3. Mucus traps particles, pathogen and dust and prevents them from getting into lungs
4. Cilia cells contain lots of mitochondria for energy