Exchange and transport Module 3

Question 1

How do small animals SA:V ratio compare to larger animals?

Answer 1

Smaller animals have a much larger SA to volume ratio

Question 2

What does having exchange surfaces allow for single celled organisms?

Answer 2

Substances can diffuse directly in or out of the cell, across the cell surface membrane, as small distances for substances to travel

Question 3

In multi-cellular animals why can’t they rely on diffusion directly from the outer membrane?

Answer 3

Some cells are deep within the body, there’s a big distance between them and the outside environment

Larger animals have a smaller SA:V ratio, meaning difficult to supply enough substances for a large volume when diffusing across a small surface area

Have a higher metabolic rate than single celled, so use up oxygen and glucose faster

Question 4

3 Special features exchange surfaces have to increase their efficiency?

Answer 4

Large surface area
Thin
Good supply and or ventillation

Question 5

Example of an exchange surface with a large surface area?

Answer 5

The cells on plant root grow into long root hairs, which stick out into the soil, increasing it’s surface area, increasing it’s rate of absorption of water by osmosis and mineral ions by active transport

Question 6

Example of an exchange surface with a small surface area?

Answer 6

The alveoli, each alveolus is made from a single layer of thin flat cells called alveolar epithelium
Oxygen diffuses out of the alveolar space and into the blood, CO2 diffuses the opposite way
Thin layer of cells decreases distance substances have to travel, and therefore increases diffusion

Question 7

Example of exchange surface with a good blood supply and or ventillation?

Answer 7

Alveoli, surrounded by large capillary network so each one has it’s own blood supply so Oxygen constantly taken away and CO2 constantly taken in. Also lungs are well ventilated meaning air in alveoli constantly replenished and therefore CO2 and O2 concentrations maintained

Question 8

Describe the journey of air as you breath in?

Answer 8

Air enters the trachea

The trachea splits into 2 bronchi, each bronchus leading to each lung

Each bronchus then then branches off into smaller tubes called bronchioles

The bronchioles end in small air sacs called alveoli, where gasses are exchanged

Question 9

Function of goblet cell lining the airways?

Answer 9

Secrete mucus, which traps microorganisms and dust particles in the inhaled air preventing them reaching the alveoli

Question 10

What do cilia on the surface of cells lining the airways do?

Answer 10

Beat the mucus, moving the muscus and trapped microorganisms and dust away from the alveoli, and towards the throat where it is swallowed.

Prevents lung infections

Question 11

Function of fibres in the walls of the trachea, bronchi, bronchioles and alveoli?

Answer 11

Help with the process of breathing out, as during breathing in they are stretched, and they recoil in the process of exhaling

Question 12

Function of smooth muscle in the trachea, bronchi and bronchioles?

Answer 12

Allows their diameter to be controlled, during exercise smooth muscle relaxes and increases the diameter of the tubes, so air can flow in and out easier

Question 13

Function of rings of cartilage in the walls of the trachea and bronchi?

Answer 13

Provide support, strong and flexible, so prevents the trachea and bronchi collapsing when you breath in and the pressure drops

Question 14

What shape cartilage does the trachea have?

Answer 14

C-shaped

Question 15

Describe what happens during inspiration?

Answer 15

The external intercostal and diaphragm muscles contract
Causing the ribcage to move upwards and outwards and the diaphragm to flatten, increasing the volume of the thorax
As the volume of the thorax increases, the lung pressure decreases, causing air to flow into the lungs

Active process so required ATP

Question 16

Describe what happens during expiration?

Answer 16

The external intercostal and diaphragm muscles relax
Causing the ribcage to move downwards and inwards the diaphragm becomes curved again
The thorax volume decreases, causing causing the air pressure to increase above atmospheric pressure
Air is forced out of the lungs

Normal expiration is a passive process (doesn’t require energy),

Forced expiration does require energy (internal intercostal muscles contract to pull the ribage down and in)

Question 17

What’s the tidal volume?

Answer 17

The volume of air in each breath

Question 18

What’s the vital capacity?

Answer 18

The maximum volume of air that can be breathed in or out (capacity of the lungs)

Question 19

How does a spirometer give reading for tidal volume, vital capacity, breathing rate, and oxygen uptake?

Answer 19

Spirometer has an oxygen filled chamber with a movable lid

The person breathes through a tube connected to the chamber, causing the lid to move up and down

These movements can be recorded by a pen attached to the lid of the chamber, and it writes on a rotating drum, creating a spirometer trace

The soda lime in the tube absorbs the CO2

Question 20

In a spirometer why does the total volume of gas in the chamber decrease?

Answer 20

The air that is breathed out is a mixture of CO2 and O2, but CO2 is absorbed by soda lime, so only O2 is inhaled by the patient who uses it for respiration aswell, so total volume decreases

Question 21

How do you find the breathing rate, tidal volume, vital capacity and oxygen consumption for a spirometer trace?

Answer 21

Breathing rate:
Count the amount of peaks in a time frame

Tidal volume:
Volume between the peak and trough in the normal breathing section

Vital capacity:
Volume between the largest inhale and exhale

Oxygen consumption:
Create a triangle by drawing a trace down the top of the peaks until a specific time frame, and then draw a line vertical from end point, connecting with hoizontal line from starting volume, calculate the volume between them to calculate oxygen consumption per the time frame drawn to

Question 22

Describe the structure of a gill?

Answer 22

Made of thin branches called gill filaments or primary lamellae, which give a big surface area for exchange of gases

Gil filaments are covered in lots of tiny structures called gill plates or secondary lamellae which increase the surface area even more, and have lots of blood capillaries and thin surface layer of cells to speed up diffusion

Each gill is supported by a gill arch

Question 23

Describe the counter-current system in fish for gas exchange?

Answer 23

Water containing oxygen enters the fish through it’s mouth and passes out through the gills

Blood flows over the gill plates in one direction, and water flows over in the opposite direction

This is a counter current system as it maintains a large concentration gradient between the water and blood, as the oxygen concentration is always higher in the water, than the blood, so it’s always diffusing into the blood

Question 24

Describe how the gills are usually ventillated in bony fish?

Answer 24

The fish opens it’s mouth, which lowers the floor of the buccal cavity
The volume of the buccal cavity increases, decreasing the pressure so water is sucked in
When the fish closes it’s mouth the floor of the buccal cavity raises, the volume inside decreases and the pressure increases, water is forced out of the cavity and across the gill fillaments

Each gil is covered by a tiny bony flap called the operculum which when the pressure increases opens on each side of the head and allows water to leave the gills

Question 25

Describe how insects exchange gases?

Answer 25

Insects have microscopic air-filled pipes called tracheae which they use for gas exchange

Air moves into the trachea through pores on the insects surface called spiracles

Oxygen travels down the concentration towards the cells, whilst CO2 from the cells moves down it’s own concentration gradient towards the spiracles to be released

The trachea branch off into smaller tracheoles which have thin permeable walls and go to individual cells. The tracheoles also contain fluid in which oxygen dissolves in

The oxygen then diffuses from this fluid into body cells, CO2 diffues in the opposite direction

Insects use abnominal movents to change the volume of their bodies, and move air in and out of the spiracles. (wing movements can pump their thorax’s too)

Question 26

Out of the trachea, bronchi, larger bronchiole, smaller bronchiole, and smallest bronchiole and aleveoli, which contain cartilage, smooth muscle, elastic fibres, goblet cells, epithelium?

Answer 26

Cartilage:
Trachea has C shaped
Bronchi has smaller pieces
The rest have none

Smooth muscle:
All have smooth muscle apart from smallest bronchiole and alveoli

Elastic fibres:
ALL

Goblet cells:
Only trachea, bronchi and largest bronchioles

Epithelium:
Trachea, bronchi, larger and smaller bronchioles all have cilitated epithelium, smallest bronchiole and alveoli don’t have any

Question 27

Rings of what support trachea?

Answer 27

Chitin