Exchange Surfaces

Question 1

Features of specialised exchange ssytem

Answer 1

Increased surface area- Provides area needed for exchange and overcomes limitations of SA:V ratio of larger organisms e.g. root hair

Thin layers- DIstances for diffusion are ashort, making the process fast and efficient

Good blood supply- Steeper concentration gradeint, faster diffusion rate= substances contstly removd from surface

Ventilation to maintain diffusion gradient- Gases, helps maintain concentration gradeints adn makes process more efficient

Question 2

Why do humans have to have a specialized gaseous exchange system

Answer 2

Need to take in lots of o2 and therefore§ remove co2
High metabolic rate because they ate active and maintain body temp
Relatively big
Small sa:V ratio

Question 3

Key structures in human gaseous exchange system

Answer 3

Nasal cavity 
Trachea 
Bronchus 
Bronchioles
Alveoli

Question 4

Nasal cavity

Answer 4

Large surface area with good blood supply, warm air to body temp
Hairy lining, secretes mucus and traps dust
Moist surfaces increase humidity of incoming air reducing evaporation

Question 5

Trachea

Answer 5

The main airway carrying clean warm and moist air from the nose down teh chest
Wide tube supported by incomplete rings of strong flexible cartidifge , stopping it from collapsing( incomplete so food can easily move down oesphagus)
Lucid with ciliated epithelium

Question 6

Bronchus

Answer 6

In the chest cavity, trachea divides to form left bronchus = left lung and right bronchus leading to right lung
Similar structure to trachea
Small supporting rings on cartilage

Question 7

Bronchi oles

Answer 7

In the lungs bronchi divide to form bronchi oles
Smaller bronchioles( 1mm) have no cardilidge
The walls of the broncholes contain smooth muscle, When the smooth muscle contracts, bronchioles constrict
When it relaxes, the bornchioles dilate( open up), this changes the amount of air reaching teh lungs.
Lined with thin layer of flattened epithelium

Question 8

Alevoli

Answer 8

Tiny air sacs, main gas exchange surfaces of bod
Diameter of 200-300 um
Layer of thin, flattered epithelial cells+ some collagen and elastic fibers
Elastic tissues allow alveloi to stretch as air is drawn in and return to their resting size= squeeze air out
= ELASTIC RECOIL

Question 9

Adaptations of alveoli

Answer 9

Large surface area( 300-500 per lung, 50-75km2)

Thin layers- 1 cell thick

Good blood supply- Constant flow

Good ventilation- Breathing moves air in and out of the alveoli, helping maintain steep diffusion gradients of co2 and o2 between blood and air lungs

Question 10

Lung surfacant

Answer 10

Inner surface of alveoli

Makes it possible for alveolar to remain inflated, o2 dissolved in water before diffusing into the blood

Question 11

The lungs - why is air moved into and out

Answer 11

Pressure exhanges in teh thorax brought by breathing movements

Question 12

What is ventilation?

Answer 12

Movement of air

Question 13

What is the thorax?

Answer 13

Chest cavity

Lined by pleural membranes

Question 14

Where are the intercoastal and external muscles found

Answer 14

Between ribs

Question 15

What is inspiration?

Answer 15

Taking in air

Uses energy

Question 16

Steps for inspiration

Answer 16

Diaphragm( dome shaped), contracts, flatterning and lowering
The external intercostal muscles contract,moving the ribs upwards and outwards
The volume of thorax increases= pressure reduced
Lower pressure than that of atmospheric air, so drawn in

Question 17

Steps for expiration

Answer 17

Muscles in diaphragm relax
Moves up into resting domed shape
External intercostal muscles relax, ribs move down and inwards under gravity
Elastic fibers in the alveoli of lungs return to normal length
Decrease volume of throax
Pressure inside the thorax greater than atmospheric air, air moves out of lungs

Question 18

Peak flow meter

Answer 18

Used to measure rate at which air can be expelled q

Question 19

Vitalographs

Answer 19

Sophisticated version of peak flow meter, the patient breathes as quickly as tehy can = graph of the anout of air and how fast its breathed out

Question 20

Spirometer

Answer 20

Measure aspects of lung volume or breathing

Question 21

Features of a spirometer

Answer 21

Soda lime absorbs co2 from exhaled air 
Enough air/oxygen and sterile medical grade 
Nose clip
check helath 
All seals secure
Not too mcuh water

Question 22

TIdal volume

Answer 22

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

Question 23

Vital capacity

Answer 23

Volume of air that can be breathed in whne the strognest possible exhalation is followed by deepest breath

Question 24

Inspiratory reverse volume

Answer 24

Max volume of air you can breathe in over adn above normal inhalation = EXTRA

Question 25

Expiratory reserve volume

Answer 25

Extra air you can force out of lungs aboce normal tidal volume you can breathe out

Question 26

Residual volume

Answer 26

Air left in lungs when exhaled hard

Question 27

Total lung capacity

Answer 27

Residual volume + vital capacity

Question 28

Breathing rate

Answer 28

Breaths per minute

Question 29

Ventilation rate

Answer 29

Total volume of air inhaled in 1 minute ( tidal * breathing rate per minute