3 - MZH - Mammalian gaseous exchange

Question 1

Why do larger organisms need specialised gaseous exchange systems?

Answer 1

SA:Vol ratio is too low for diffusion.

Distances from surface to the tissues to too great.

High metabolic rate compared to unicellular organisms so demand for oxygen is greater.

Question 2

During inspiration and expiration what happens to the:

Diaphragm muscles

Intercostal muscles

Volume of thorax

Pressure in lungs

Answer 2

Question 3

Function of:

Cartiladge

Answer 3

Provides strength to trachea and bronchi, holding open the airways so there is little resistance to air flow

Question 4

Function of:

Goblet cells

Answer 4

Secrete mucus which is sticky and trapss particles of dust, fungal spores and bacteria

Question 5

Function of:

Ciliated epithilial cells

Answer 5

Cilia moves mucus up the airways out of the lungs

Question 6

Function of:

Smooth muscle

Answer 6

Contracts, it will constrict the airway makng the lumen of the airway narrower. Effect us most obvious in the bronchioles whenconstricting the airways reduces the flow of air to and from the alveoli

Question 7

Function of:

Elastic fibres

Answer 7

Smooth muscle can only contract. Elastic fibres allow the smooth muscle to relax/recoil back to it’s original state before contraction

Question 8

Function of:

Squamous epilelium

Answer 8

Gives a short diffusion pathway for oxygen and carbon dioxide in the alveoli

Question 9

Define inspiration and expiration

Answer 9

Inspiration = Air being pushed into the lungs from the atmosphere providing fresh air to the alveoli

Expiration = Air being forced out of the lungs to the atmosphere removing stale air from the alveoli

Question 10

What does diaphragm muscle do?

Answer 10

When it contracts it pulls the diaphragm downwards to increase volume of the thoracic cavity

Question 11

What does the external intercostal muscles do?

Answer 11

They’re attached to the outside of the ribs. When they contract they pull the ribs upwards and outwards to increase volume inside the thoracic cavity

Question 12

Breathing rate = ?

Units = ?

Answer 12

Breathing rate = Number of peaks per minute

Number of breaths per minute

Question 13

Mean tital volume = ?

Units = ?

Answer 13

Mean tidal volume = Mean of sevel tidal volumes from the trace

Units = dm³

Question 14

Ventilation rate = ?

Units = ?

Answer 14

Volume of air taken into the lungs per minute

Ventilation rate = Breathing rate x mean tidal volume

Units = dm³

Question 15

Oxygen consumption

Units = ?

Answer 15

Decrease in preaks over a period of 1 minute

Question 16

What is breathing rate?

Answer 16

The number of breaths per minute

Question 17

What is tidal volume

Answer 17

Volume breathed out of the lungs in one breath

Question 18

What is oxygen uptake

Answer 18

Everytime the person breathes out the volume is less than for the previous expiration this represents the oxygen that has been absorbed by the lungs in that breath

Question 19

Vital capacity

Answer 19

Maximum volume of air that can be breathed in adn out of the lungs in one breath.

Often approx 5dm³ but it depends on many factors such as age, fitnes and state of health

Question 20

What is a spirometer?

Answer 20

Used to measure lung volumes, breathing rates, ventilation rates and oxygen consumption

Question 21

How does the spirometer ensures tha tthe levels of CO₂ exhaled doesn’t affect the inhalation of the next breath?

Answer 21

The exhaled air returns to the chamber through the soda lime which absorbs any exhaled CO₂