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Flashcards in Exchange & Transport Deck (55):

Why is diffusion alone enough to supply the needs for single celled organisms

Metabolic activity is usually low so oxygen demands and CO2 production is low
Surface area to volume ratio is large


Problems bigger organisms face

Smaller SA:V ratio
Distance between the cells and where oxygen is needed and the supply of oxygen is too far for effective diffusion to take place.
Have high oxygen demand


What does an increased surface area do?

Gases can be exchanged quickly And in large amounts


What do thin layers do?

The distances that substances have to diffuse are short, making the process fast and efficient


What does a good blood supply do?

The steeper the concentration gradient, the faster diffusion takes place. Ensures substances are constantly delivered to and removed from the exchange surface. This maintains a steep concentration gradient for diffusion.


What does good ventilation do?

A ventilation system helps maintain a concentration gradient and makes the process more efficient.


What components do mammals have?

Small SA:V ratio
Large volume of cells
High metabolic rate as they are active and maintain body temp
Need lots of oxygen for cellular respiration.


What does the nasal cavity do

Large surface area with good blood supply, which warms the air
Hairy lining which secretes mucus to trap dust and bacteria
Moist surfaces which increases the humidity of the incoming air reducing evaporation


What is the trachea

The main airway carrying clean warm moist air from the nose to chest.
Wide tube made of incomplete rings of cartilage which stop it from collapsing


What do goblet cells do

Secrete mucus onto the lining of the trachea to trap dust that have escaped the nasal cavity


What do ciliated epithelial cell’s do?

The cilia beat and move the mucus away from the lungs.


Structure of bronchus

Trachea divides to form bronchus. Similar structure to trachea with same rings of cartilage but are smaller


What do bronchioles do

Bronchi divide into small bronchioles. Small ones have no cartilage rings. Walls of them contain smooth muscle.
Lined with thin layer of flattened epithelium


What happens when smooth muscle of bronchioles contract

Bronchioles constrict- changes amount of air reaching lungs


What happens when smooth muscle of bronchioles relax

The bronchioles dilate- which changes amount of air reaching lungs


What do the alveoli do

Tiny air sacs which are the main exchange surfaces of the body
Consist of a layer of thin flattened epithelial cells along with some collagen and elastic fibres. The elastic tissues allow the alveoli to stretch as air is drawn in- elastic recoil


What allows alveoli to remain inflated?

Lung surfactant


Define ventilation

Movement of air
(In and out of the lungs)


What happens during inspiration

Diaphragm contracts and flattens
External intercostal muscles contract, moving the ribs upwards and outwards
Volume of thorax increased so pressure reduces, and is now lower than atmospheric pressure so air is drawn in


What happens during expiration

Diaphragm relaxes and turns dome shaped
External intercostal muscles relax so ribs move down and inwards.
Pressure is greater than atmospheric pressure so air moves out of lungs


What happens when you exhale forcibly?

You use energy
Internal intercostal muscles contract pulling the ribs down hard and fast and the abdominal muscles contract forcing the diaphragm up to increase pressure rapidly


What is a peak flow meter

Measures the rate at which air can be expelled from the lungs


What are vitalographs

Produces a growth of the amount of air breathed out and how quickly it is done so


What is a spirometer

Measures lung volume/ ventilation


What is tidal volume

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


What is vital capacity

Volume of air that can be breathed in when the strongest possible exhalation is followed by the deepest intake of breath


Wha is inspiratory reserve volume

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


What is exploratory reserve volume

Extra amount of air you can force out of your lungs over and above the normal tidal volume you breathe out


What is residual volume

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


What is total lung capacity

The sum of the vital capacity and the residual volume


What is the breathing rate

Number of breaths taken per minute


How to work out ventilation rate

Tidal volume x breathing rate (per minute)


What does an insect have the prevents gas exchange

A tough exoskeleton and no blood pigments that can carry oxygen


What are spiracles

Small openings along the thorax and abdomen


How are spiracles opened and closed

By sphincters


What are the tracheae (insects)

Carry air into the body and run into and along the body


What are the tracheae tunes lined with

Chitin- keeps them open if they are bent or pressed and is impermeable


What is a tracheole?

A single, elongated cell with no chitin lining- freely permeable and spread throughout the tissues of the Insect


How does air move around in an insect

Moves along the tracheae and tracheoles by diffusion. Oxygen dissolves in moisture on the walls of the teacheoles and diffuses into surrounding cells.


Where is tracheal fluid and what does it do

It is found at the end of the tracheoles and limits the penetration of air for diffusion


What happens when an insect is flying

Lactic acid builds up in the tissue and water is moved out of the tracheoles via osmosis- more surface area


Alternative methods of increasing levels of gas exchange

Mechanical ventilation of the tracheal system
Collapsible enlarged tracheae or air sacs


What does a mechanical ventilation of the tracheal system do?

Air pumped into the system by muscular pumping movements of the thorax, which changes the volume of the body and the pressure in the tracheoles and tracheae- air drawn in or forced out as pressure changes


What do collapsible enlarged tracheae or air sacs do?

Increase amount of air moved through gas exchange system. Inflated and deflated by ventilating movements of the thorax


Differences between water and air

Water 1000 denser than air and 100 times thicker


How do bony fish supply inner cels with oxygen

Maintain a flow of water in one direction Over the gills


What are the features of gills

Large SA:V ratio-Gill lamellae
Good blood supply to maintain a steep concentration gradient
Thin layers


Where are gills on a bony fish

Contained in a full cavity and covered by a protective operculum which maintains a flow of water


How do fish keep a flow of water over the gills

Opening their mouth and operculum


What is ram ventilation

Ram water past the gills


What does the overlapping of the tips of adjacent gills do?

Increase the resistance to the flow of water Over the gill surfaces and slows down the movement of water- more time for gas exchange


Why is a steep concentration gradient needed?

Fast and effficient diffusion.


What does the countercurrent system between blood and water do?

Ensures the concentration gradients are maintained, allowing more gas exchange to take place


What is the countercurrent system?

Blood and water flow in opposite directions do and oxygen concentration between them is maintained along the gill. Oxygen continues to diffuse down the favourable concentration gradient


What is a parallel system?

Blood in the gills and water flowing over goes in the same direction, giving a steep oxygen concentration gradient. Diffusion takes place until the concentrations are equal then no net movement of oxygen in blood occurs