BIOL 273 - Unit 5.1 + 5.2

Question 1

What does the respiratory system allow for (4)

Answer 1

1. Exchange of gases between atmosphere and blood
2. Homeostatic regulation of body pH
3. Protection from inhaled pathogens and irritating substances
4. Vocalization

Question 2

4 main processes of the respiratory system

Answer 2

1. Gas exchange between atmosphere and lungs (ventilation)
2. Gas exchange between lungs and blood - CO2 and )2
3. Transport of gases by blood - CO2 and O2
4. Exchange of gases between blood and tissues

Question 3

What structures/systems exist in the respiratory system that is involved in both ventilation and gas exchange

Answer 3

1. Conducting system - airways
2. Exchange surface - alveoli
3. Pumping system - bones and muscles of the thorax

Question 4

Describe the conducting system

Answer 4

passages or airways - lead from environment to the exchange surface of the lungs

Question 5

What two parts can the conducting system divide into and what strucutres are involved

Answer 5

1. Upper respiratory tract
   - Mouth, nasal cavity, pharynx, larynx
2. Lower respiratory tract
   - Trachea, bronchi, bronchioles, lungs

Question 6

Describe the exchange surface

Answer 6

• sites of gas exchange - the alveoli
• tiny hollow sacs found at the ends of the terminal bronchiole
• wrapped with an extensive capillary network which covers 80-90% of the alveolar surface

Question 7

Gas exchange occurs by diffusion between…

Answer 7

alveoli and capillary

Question 8

What are the types of alveoli cells

Answer 8

1. Type I alveolar cells - large but thin
2. Type II alveolar cells - smaller but thicker

Question 9

Function of Type I alveolar cells

Answer 9

rapid gas diffusion

Question 10

Function of Type II alveolar cells

Answer 10

synthesize and secrete surfactant (used to decrease surface tension to keep lung inflated)

Question 11

What allows exchange with alveoli

Answer 11

blood vessels of the pulmonary circulation

Question 12

Why is rate of blood flow high

Answer 12

becuse all the output of the right ventricle goes to the lungs vs. whole body for the blood leaving the left ventricle

Question 13

Describe the pumping system

Answer 13

bones and muscle of the thorax allow for ventilation (inspiration and expiration)

Question 14

What are the two lungs surrounded by

Answer 14

the pleural sac - forms a double membrane around each lung
- pleura is filled with fluid
- Acts as a lubricant

Question 15

Describe the relationship between volume and pressure of a gas

Answer 15

inversely related

Question 16

Amount of gas will dissolve in a liquid is determined by…

Answer 16

1. Partial pressure of the gas
2. Solubility of the gas in the liquid

Question 17

Partial pressure of an atmospheric gas equation

Answer 17

Pressure of atmosphere x % of gas in atmosphere

Question 18

Pressure volume relationships: Boyle’s Law

Answer 18

P1V1 = P2V2

Question 19

What is critical for ventilation

Answer 19

pressure-volume relationship
- during inspiration and expiration, the volume of the thoracic cavity changes

• this causes changes in the alveolar pressure

Question 20

How does volume change occur in the lungs

Answer 20

• lungs do not have muscles so they cannot change volume on their own
• the muscles are in the chest wall - contraction will change thoracic volume

Question 21

What does the volume in the chest depend on

Answer 21

1. The transpulmonary pressure - difference between alveolar pressure and intrapleural pressure
2. Degree of elasticity of lungs

Question 22

What is the pressure inside the lungs referred to as

Answer 22

the alveolar pressure

Question 23

What is the pressure outside the lungs referred to as

Answer 23

pressure in the intrapleural fluid

Question 24

Importance of airways in ventilation and their requirements

Answer 24

• Airways serve an important role in conditioning the air before it reaches the lungs

1. Warm air to 37 degrees to maintain core body temp and protect alveoli
2. Add water vapour to air to prevent drying of epithelia
3. Filter out foreign material

Question 25

Describe the process of filtering foreign material in the airways using watery saline solution

Answer 25

- cells move Cl from ECF into the cell via the NKCC - Cl transported to lumen of airway via apical anion channel - Na+ moves between cells from ECF to lumen - concentration gradient of NaCl draws water towards the lumen creating the watery saline solution

Question 26

What type of cells located in ciliated epithelia secretes mucous

Answer 26

goblet cells

Question 27

Describes how mucous is involved in the filtering of foreign material in the airways

Answer 27

- Mucous contains immune cells that kill invaders - Mucus is moved up to the pharynx (mucus escalator) - Transferred to the digestive tract where additional bacteria are destroyed - transported by cilia

Question 28

Describe the steps of inspiration

Answer 28

1. Somatic motor neurons trigger contraction of diaphragm and inspiratory muscles (external intercostals contract) 2. Thorax expands - thoracic volume up 3. Alveolar and intrapleural pressure decreases 4. Lungs expand resulting in air flowing into lungs

Question 29

Describe the steps of Expiration

Answer 29

1. Impulses from somatic motor neurons stop 2. Diaphragm and thoracic muscles relax which returns thorax to their original positions - volume down 3. Alveolar and intrapleural pressure increases 4. Elastic recoil of the lungs decreases lung volume - air flows out of the lungs

Question 30

Describe expiration during quiet breathing

Answer 30

expiration is a passive process - depends on elastic recoil of the thoracic muscles and the lungs

Question 31

Describe expiration during heavy breathing

Answer 31

expiration is an active process - depends on contraction of internal intercostals and abdominal muscles

Question 32

Which muscles contract during inspiration? Which muscles are active during expiration?

Answer 32

Inspiration - external intercostals Expiration - internal intercostals

Question 33

Describe the Intrapleural pressure in the lung and explain why is it this way

Answer 33

sub- atmospheric: having lower pressure in the pleural fluid (outside lung) than inside lung helps keep lung expanded and open

Question 34

What happens to intrapleural pressure when air gets into pleural cavity

Answer 34

pressure increases

Question 35

Pneumothorax

Answer 35

when pressure difference between in and outside of the lungs is abolished (lung collapse)

Question 36

What are the two factors for breathing

Answer 36

1. Compliance (stretchability) of the lungs 2. The resistance to air flow in the airways