3.1.1 Exchange surfaces

Question 1

Method of gas exchange in single called organisms?

Answer 1

Simple diffusion

Question 2

Why do single celled organisms not need specialised exchange surfaces?

Answer 2

• Short diffusion distance due to high SA:V ratio
• Low metabolic activity

Question 3

Why do multi celled organisms need specialised exchange surfaces?

Answer 3

• Long diffusion distance due to low SA:V ratio
• High metabolic activity

Question 4

How is increased SA a feature of efficient gas exchange?

Answer 4

Overcomes limitations of low SA:V ratio

Question 5

How are thin layers a feature of efficient gas exchange?

Answer 5

Allows for shorter diffusion distances

Question 6

How is a good blood supply a feature of efficient gas exchange?

Answer 6

Maintains steep concentration gradient so faster diffusion

Question 7

How is ventilation a feature of efficient gas exchange?

Answer 7

For gases it maintains a steep concentration gradient so faster diffusion

Question 8

Pathway of air in mammalian gas exchange system?

Answer 8

Nasal cavity -> trachea -> bronchus -> bronchioles -> alveoli

Question 9

Why does the nasal cavity have a good blood supply and moist surfaces?

Answer 9

To warm incoming air and create a humid environment (reduced water loss)

Question 10

Why are the trachea rings incomplete?

Answer 10

To allow it to bend when food travels down the oesophagus

Question 11

What is the trachea supported by?

Answer 11

Incomplete rings of cartilage

Question 12

What is the trachea lined with?

Answer 12

Ciliated epithelial and goblet cells

Question 13

What component is similar in structure to the trachea, but is smaller?

Answer 13

Bronchus

Question 14

What is the structure of bronchioles?

Answer 14

No cartilage rings, have smooth muscle and elastic fibres instead

Question 15

Diameter of alveoli?

Answer 15

200-300 µm

Question 16

What are alveoli made up of?

Answer 16

Thin layer of flattened epithelial cells, collagen and elastic fibres

Question 17

Function of elastic fibres in alveoli?

Answer 17

Can stretch when air is drawn in and then return to original size (elastic recoil)

Question 18

Adaptations of alveoli?

Answer 18

• Large SA
• Thin walls
• Good blood supply
• Good ventilation
• Liquid surfactant

Question 19

Function of liquid surfactant on alveoli?

Answer 19

Prevent water loss

Question 20

There is a _______ concentration of oxygen in the alveoli
There is a _______ concentration of oxygen in the blood

Answer 20

High
Low

Question 21

Inspiration is an _________ process

Answer 21

Active

Question 22

Exhalation is a _________ process

Answer 22

Passive

Question 23

INHALATION

External intercostal muscles __________

Answer 23

Contract

Question 24

INHALATION

Rib cage moves ____ and _____

Answer 24

Up and out (expands)

Question 25

INHALATION Diaphragm __________ and __________

Answer 25

Contracts (moves down) Flattens

Question 26

INHALATION Volume of thorax __________

Answer 26

Increases

Question 27

INHALATION Pressure inside thorax _________ until slightly _______ than atmospheric pressure

Answer 27

Decrease Lower

Question 28

What is the mechanism of **inhalation** during **exercising**?

Answer 28

Same mechanism as without exercise

Question 29

EXHALATION External intercostal muscles _______

Answer 29

Relax

Question 30

EXHALATION Rib cage moves ____ and _____

Answer 30

Down and in

Question 31

EXHALATION Diaphragm __________ and becomes __________

Answer 31

Relaxes (moves up) Dome shaped

Question 32

EXHALATION Volume of thorax __________

Answer 32

Decreases

Question 33

EXHALATION Pressure inside thorax _________

Answer 33

Increases

Question 34

FORCED EXHALATION (exercising) ________ intercostal muscles ________

Answer 34

Internal Contract

Question 35

FORCED EXHALATION (exercising) Ribcage pulled _______ and ______

Answer 35

Down Back

Question 36

What do the abdominal muscles do during forced exhalation?

Answer 36

Contract to push organs upwards against the diaphragm, increasing the internal pressure

Question 37

What happens in asthma?

Answer 37

- Epithelial cells become inflamed - Goblet cells secret excess mucus - Smooth muscle in bronchioles contract - Airways narrowed

Question 38

What is tidal volume?

Answer 38

Volume of air that moves into and out of the lungs with each resting breath

Question 39

What is vital capacity?

Answer 39

Maximum volume of air that can be breathed in or out in one breath

Question 40

What is inspiratory reserve volume?

Answer 40

Maximum volume of air you can breathe in above a normal inhalation

Question 41

What is expiratory reserve volume?

Answer 41

Extra amount of air you can force out above the normal tidal volume of air you breathe out

Question 42

What is residual volume?

Answer 42

Volume of air left in lungs when you have exhaled as hard as possible

Question 43

What is total lung capacity?

Answer 43

Sum of the vital capacity and residual volume

Question 44

What is breathing rate?

Answer 44

Number of breaths (in and out) taken in one minute

Question 45

How to calculate ventilation rate?

Answer 45

Tidal volume x breathing rate (per min)

Question 46

What happens to tidal volume during exercise?

Answer 46

Increases

Question 47

What is the normal breathing rate?

Answer 47

12-18 breaths per minute

Question 48

What does a spirometer show?

Answer 48

- Vital capacity - Tidal volume - Breathing rate

Question 49

What does each curve on a spirometer represent?

Answer 49

Breathing rate

Question 50

What does the vertical size of each curve on a spirometer represent?

Answer 50

Tidal volume

Question 51

How does gas exchange occur in insects?

Answer 51

Tracheal system

Question 52

What is a spiracle?

Answer 52

Opening in the exoskeleton which has valves and allows air to enter

Question 53

What are the valves in a spiracle called?

Answer 53

Sphincters

Question 54

Why does a spiracle need valves?

Answer 54

- To control the opening and closing of it - Closed most of the time to prevent water loss

Question 55

Structure of trachea in insects?

Answer 55

Lined by spirals of chitin which provide support

Question 56

Function of tracheoles in insects?

Answer 56

Site of gas exchange

Question 57

Function of tracheal fluid?

Answer 57

- Provides barrier that prevents oxygen from moving - When insect is moving then fluid is stopped to create more space for gas exchange

Question 58

Mechanism of ventilation in insects?

Answer 58

- Air sacs inflating and deflating - Abdominal muscles creating pumping movement

Question 59

Gas exchange system in fish?

Answer 59

Gills

Question 60

Why do fish gills have stacks of filaments that overlap?

Answer 60

To slow movement of water so there us more time for gas exchange

Question 61

Why do the filaments on fish gills have rows of lamellae?

Answer 61

To increase SA

Question 62

What do lamellae contain?

Answer 62

A rich blood supply of capillaries

Question 63

What is a counter current system?

Answer 63

Blood flow is in the opposite direction to water flow with a constant gradient between them

Question 64

Why is the counter current system needed?

Answer 64

To ensure concentration gradient is maintained

Question 65

In fish gills the water with ________ oxygen concentration is found adjacent to the __________ blood

Answer 65

Lowest Deoxygenated

Question 66

INHALATION IN FISH - Fish _______ mouth - Buccal cavity floor ________ - Volume ________ - Pressure _______ - Pressure is higher outside of mouth so water flows in

Answer 66

- Open - Lowers - Increases - Decreases

Question 67

EXHALATION IN FISH - Fish _____ mouth - Buccal cavity floor ______ - Pressure ________ in buccal cavity - Water flows from buccal cavity to _________ (high to low pressure) - Pressure increases in ________ - _________ forced open and water exists

Answer 67

- Closes - Rises - Increases - Gill cavity (x2) - Operculum

Question 68

What is operculum?

Answer 68

Flap of tissue covering gills