Human Gas Exchange System + Ventilation

Question 1

What is the main function of the human gas exchange system?

(alw. O diff. bld. + CO2 diff. o/bld.)

Answer 1

To allow oxygen to diffuse into the blood and carbon dioxide to diffuse out of the blood

Question 2

Why must carbon dioxide be removed from the body?

(bldup. CO2 - hrmfl. - lwr pH + afct. enz actvty.)

Answer 2

A buildup of carbon dioxide can be harmful, as it can lower pH and affect enzyme activity

Question 3

What specialised surface have mammals evolved for gas exchange?

Answer 3

Lungs

Question 4

Why are the lungs located inside the body?

1. A = /dnse. - spprt./prct. delcte. lng. strctres.
2. Prev. wtr. lss = bdy. dryng.

Answer 4

1/ Air is not dense enough to support and protect the delicate lung structures

2/ To prevent excessive water loss and the body drying out

Question 5

Label the diagram of the human gas exchange system

Answer 5

1. Bronchi
2. Bronchioles
3. Trachea
4. Alveoli
5. Internal intercostal muscles
6. External intercostal muscles
7. Diaphragm

Question 6

What structure protects and support the lungs?

Answer 6

The rib cage

Question 7

What are the lungs?

(pr. lbd. strctrs. cont. hghly. brnch. bronc. - end. alvli.)

Answer 7

A pair of lobed structures containing highly branched bronchioles that end in alveoli

Question 8

How is the trachea adapted for its function?

(C shpe. rngs. ctrlge. - prvnt. clpse. - lmen. lnd. w/ cltd. epthlem. + glbt. clls. = prod. mucs. - trp. pthgns.)

Answer 8

Has C - shaped rings of cartilage to prevent collapse. The lumen is lined with cilated epithelium and goblet cels. The goblet cells produces mucus to trap pathogens

Question 9

What is the role of cilated epithelial cells in the trachea and bronchi?

Answer 9

Cilia waft mucus containing trapped pathogens towards the throat

Question 10

What are the bronchi, and how do they function?

Answer 10

The bronchi are two divisions of the trachea, each leading to a lung.

They have mucus - producing goblet cells and cilia to move mucus to the throat.

Question 11

How are bronchioles structurally adapted to control airflow?

(ct. smth. musc. - cntrct/rlx - cont. flw. air - alvli.)

Answer 11

They contain smooth muscle which can contract or relax to control the flow of air to the alveoli

Question 12

Why do bronchioles not contain cartilage?

(dimtr. cont. smth. musc. > crtlge.)

Answer 12

Their diameter is controlled by smooth muscle rather than cartilage

Question 13

How do elastic fibres in the alveoli aid gas exchange?

(alw. alvli. - strch. durg. inh. + rcl. dur. exh. - aid. vntltn.)

Answer 13

They allow the alveoli to stretch during inhalation and recoil during exhalation to aid ventilation

Question 14

What is ventilation, and what is it also known as?

(prc. mve. air in/out - lngs. - mntn. diff. gses. acrs. alvelr. epthlem.)

Answer 14

The process of moving air in and out of the lungs to maintain diffusion of gases across the alveolar epithelium
BREATHING

Question 15

What happens to the intercostal muscles during inspiration (inhalation)?

Answer 15

External intercostal muscles contract and internal intercostal muscles relax

Question 16

How does the ribcage move during inspiration (inhalation)?

Answer 16

The ribs pulled upwards and outwards, increasing the volume of the thorax

Question 17

Outline how inspiration (inhalation) occurs in the lungs

1. External IM contract - Internal IM relaxes
2. Ribs - up + out - volume inc. - thorax
3. Diaphragm contract - flattens - inc thoracic vol
4. Inc thoracic volume - lung P decreases
5. ATM pressure > LUNG pressure = air forced in

Answer 17

1. The external intercostal muscles contract whilst the internal intercostal muscles relax
2. The ribs move upwards and outwards, increasing the volume of the thorax
3. The diaphragm’s muscles contract, causing it to flatten increasing the thorax’s volume
4. Increase in thoracic volume, reduces lung pressure
5. Atmospheric pressure is now greater than the pulmonary pressure so air is forced into the lungs

Question 18

What happens to intercostal muscles during expiration (exhalation)?

Answer 18

Internal intercostal muscles contract, and external intercostal muscles relax

Question 19

How does the rib cage move during expiration (exhalation)?

Answer 19

The ribs move down and inwards, decreasing the volume of thorax

Question 20

Outline how expiration (exhalation) occurs in the lungs

1. Internal IM contract - External IM relax
2. Ribs - down + in - thoracic vol = decreases
3. Diaphragm - relax - pushed up - contents of abdomen - thorax volume - decreases
4. Low vol in thorax - inc lung pressure
5. ATM p < LUNG p = air forced out

Answer 20

1. The internal intercostal muscles contract whilst the external intercostal muscles relax
2. The ribs move down and inwards, decreasing the thoracic volume
3. The diaphragm muscles relax, being pushed up by the contents of the abdomen, the thoracic volume further decreases
4. The low volume in the thorax, increases the pressure of the lungs
5. The atmospheric pressure is now less than the pulmonary pressure, so air is forced out of the lungs

Question 21

Where are the intercostal muscles located?

Answer 21

Between the ribs

Question 22

Name the two types of intercostal muscles

Answer 22

Internal intercostal muscles and external intercostal muscles

Question 23

What is pulmonary ventilation rate?

(ttl. vol. air. mvd. lngs. - 1min)

Answer 23

The total volume of air moved into the lungs in one minute

Question 24

State the equation for pulmonary ventilation rate

Answer 24

Pulmonary ventilation rate = tidal volume x breathing rate

Question 25

What are the units of pulmonary ventilation rate?

Answer 25

dm³ min⁻¹

Question 26

What is tidal volume?

Answer 26

The volume of air taken in per breath at rest

Question 27

What is breathing (ventilation) rate?

Answer 27

The number of breaths taken per minute