Definition of alveoli
Tiny folds of the living epithelium to increase SA
Definition of bronchi/bronchioles
Small airways leading into lungs
Definition of diaphragm
Layer of muscle beneath lungs
Definition of intercostal muscles
Muscles between ribs, which contract to raise ribcage
Definition of trachea
Main airway leading from back of mouth to lungs
Definition of ventilation
Refreshing of the air in the lungs, so there's a higher oxygen conc than in blood and lower conc of CO2
Definition of cartilage
Form of connective tissue
Definition of ciliated epithelium
Layer of cells that have many cilia
Definition of elastic fibres
Protein fibres that can deform then recoil to their original size
Definition of goblet cells
Cells that secrete mucus
Definition of smooth muscle
Involuntary muscle that contracts without the need for conscious thought
Definition of breathing rate
Number of breaths per min
Definition of oxygen uptake
Vol of O2 absorbed by lungs in one minute
Definition of tidal volume
Vol of air inhaled or exchanged in one breath, usually measured at rest
Definition of spirometer
Device that can measure movement of air into and out of lungs
Definition of vital capacity
The greatest vol of air that can be expelled from lungs after taking the deepest possible breath
Definition of buccal cavity
The mouth
Definition of countercurrent flow
Where 2 fluids flow in opposite directions
Definition of filaments
Slender branches of tissue that make up gill (often called primary lamalle)
Definition of operculum
Bony flap that covers and protects the gills
Definition of spiracle
External opening/pore that allows air in and out of trachea
Definition of tracheal fluid
Fluid found at end of tracheoles in the tracheal system
Definition of tracheal system
System of air-filled tubes in insects
What does gaseous exchange in mammals consist of?
Lungs and airways carrying air in and out of lungs
What are the lungs?
Pair of inflatable sacs lying in chest cavity
What are the lungs protected by?
The ribcage
What holds the ribs together?
Intercostal muscles
What produces breathing movements (ventilation)?
The action of muscles and the diaphragm
How does gaseous exchange happen in the lungs?
Gases pass by diffusion through the thin walls of the alveoli
Summarise how gaseous exchange occurs in the lungs
Gases pass by diffusion through thin walls of alveoli
O2 passes from air in alveoli to bood in caps
CO2 passes from blood to air in alveoli
Must maintain steep conc grad in each direction to ensure diffusion can occur
How does O2 diffuse in gas exchange?
Passes from air in alveoli to blood in capillaries
How does CO2 diffuse in gaseous exchange?
Passes from blood to air in alveoli
What must the lungs do to ensure diffusion can occur?
Maintain a steep concentration gradient of gases in each direction
How big are individual alveoli?
100-300 micrometres
Do the lungs or skin have a larger surface area and why?
Lungs as there are many alveoli
What are the alveoli lined with?
Thin layer of moisture which evaporates and is lost as we breathe out (surfactant)
Why must the lungs produce a surfactant that coats the internal surface of the alveoli?
To reduce the cohesive forces between the water molecules as these forces tend to make alveoli class collapse
What is the barrier to gaseous exchange comprised of?
Wall of alveolus and wall of blood capillary
What do the cells and their plasma membranes of the wall of the alveolus and wall of blood capillary readily allow the diffusion of and why?
Oxygen and carbon dioxide as the molecules are small and non-polar
What are the five adaptations to reduce the distance for gaseous exchange?
Alveolus walls are one cell thick
Capillary walls are one cell thick
Both walls consist of squamous cells
Capillaries in close contact with alveolus walls
Capillaries so narrow that red blood cells are squeezed against the wall to reduce the rate of flow
How thick is the title barrier for gaseous exchange?
2 flattened cells (less than 1 micrometer thick)
What does a good blood supply do in the gaseous exchange system?
Helps maintain a steep concentration gradient so gases continue to diffuse
What does the blood system transport?
Carbon dioxide from the tissues to the lungs
What does the blood system ensure?
That the concentration of carbon dioxide in the blood is higher than that of the air in the alveoli so CO2 diffuses into the alveoli
What does blood transport?
O2 away from the lungs
What does the blood ensure?
Put the oxygen concentration in the blood is kept lower than that in the alveoli so oxygen diffuses into the blood
Why can mouth-to-mouth be effective?
In one breathing cycle the air in the lungs loses some of its oxygen content as we don't use all of the oxygen we breathe in
What's the first thing that happens during inspiration?
(Diaphragm)
Diaphragm contracts to move down and become flatter, this displaces the digestive organs downwards
What's the second step of inspiration?
(Intercostal muscles)
The external intercostal muscles contract to raise the ribs
What's the third step of inspiration?
(Volume)
Volume of chest cavity is increased
What's the fourth step of inspiration?
(Pressure)
Pressure in chest cavity drops below atmospheric pressure
What's the final step of inspiration?
(Equilibrium)
Where is moves into the lungs from trachea to obtain a pressure equilibrium
What's the first step of expiration?
Diaphragm relaxes and it's pushed up by the displaced organs underneath
What's the second step of expiration?
External intercostals relax and ribs fall, internal intercostal can contract to push air out more forcefully (usually only happens during exercise or coughing and sneezing)
What's the third step of expiration?
Volume of chest cavity is decreased
What's the fourth step of expiration?
Pressure in lungs increases and rises above the pressure in the surrounding atmosphere
What's the fifth step of expiration?
Air is moved out of the lungs to obtain a pressure equilibrium
What does ventilation ensure?
Concentration of O2 of air of alveolus remains higher than in the blood
Concentration of carbon dioxide in alveoli is lower than in the blood
What do breathing movements do?
Ventilate the lungs replacing the used air with fresh air bringing in more oxygen and removing CO2
Why is ventilation in insects and mammals similar?
An increase in volume of body cavity reduces pressure and so air enters tracheal system, a decrease in volume raises pressure to push air out again
What must bony fish exchange gases with?
The water in which they live
How do bony fish perform gaseous exchange?
They use the gills to absorb oxygen dissolved in the water and release carbon dioxide back into the water
Does water or air have a lower O2 concentration?
Water
How many pairs of gills do most bony fish have?
5
What are fishes gills covered with?
A bony plate called operculum
What does each gill consist of?
Two rows of gill filaments (primary lamalle) attached to a bony arch
Describe filaments
Very thin and their surface is folded into many secondary lamalle which provides a large surface area
What do blood capillaries do in bony fish?
Carry deoxygenated blood close to the surface of the second lamalle where exchange takes place
What does a countercurrent flow do?
Absorb the maximum amount of oxygen from the water
How is a countercurrent flow created in bony fish?
Blood flows along gill arch and and outer long filaments to secondary lamalle
Blood then flows through capillaries in opposite direction to the flow of water over the lamalle
Buccal cavity can…
Change volume
How does water keep flowing over gills?
By using buccal-opercular pump
What movements are coordinated in bony fish?
Movements of operculum and buccal cavity
How does water flow through the gills?
As water is pushed from cavity, operculum moves outwards reducing the pressure in opercular cavity
How does water move through a fish?
The floor of the mouth moves downwards drawing water into buccal cavity, mouse closes and floor is raised again pushing water through gills
What doesn't transports oxygen in the blood?
Insects
What type of circulatory system do insects have?
Open circulatory system
What's the issues with insects having an open circulatory system?
Circulation is slow and can be affected by body movements
Where does gaseous exchange occur in insects?
Between air in trancheole and tracheal fluid
How does air enter an insects tracheal system?
Via pore in each segment (spiracle)
How is air transported into an insects body?
Via series tubes - trachea which split into smaller tubes - tracheoles
Why can more O2 be absorbed when an insect is active?
When tissues active, tracheal fluid can be withdrawn into bodily fluid to increase SA of tracheole wall exposed to air
How do larger insects ventilate their tracheal system?
Movement of body - sections of tracheal system have flexible walls and are expanded, movement of wings alters vol of thorax, specialised breathing movemets to alter vol of abdomen (locusts)
How do flexible and expandable walls of an insects tracheal system help larger insects ventilate?
Act as air sacs which can be squeezed by action of flight muscles - repetitive expansion and contraction of sacs ventilates system
How does the movement of an insects wings to alter the vol of the thorax help it ventilate?
As vol decreases, air in system put under pressure and pushed out of system
When increases in vol, pressure inside drops and air drawn into system from outside
How do specialised breathing movements to alter the vol of the abdomen help locusts ventilate?
Coordinated with opening and closing valves in spiracle as abdomen expands. Spiracles at front end of body open and air enters system. As reduces in vol, spiracles at rear end open so air leaves system
What factors affect the need for a transportation system?
Size
SA:V
Level of activity
Why don’t single-celled organisms need exchange systems?
All cytoplasm very close to enviro which live - diffusion will supply enough O2 and nutrients to keep cells alive and active
Why do multicellular organisms require an effective exchange system?
Have several layers of cells - O2 and nutrients diffusing from outside have longer distance so diffusion too slow to enable sufficient supply to innermost cells
Why is it advantageous small animals have a large SA:V?
Means their SA large enough to supply all their cells with sufficient O2
How can organisms increase SA?
Adopt diff shape e.g flat worms
How is SA:V written?
X:1
Small organisms
What does metabolic activity require?
O2 to release the energy from food in aerobic resp
How does level of activity affect an organisms need for an exchange system?
Cells of active organism need good supply nutrients and O2 to supply energy needed for movement
When is the need for energy of an active organism increased?
In animals that need to keep themselves warm
What are the features of a good exchange surface?
Large S.A
Thin barrier permeable to substances being exchanged
Good blood supply
Why is a large surface area a feature of a good exchange surface?
Provides more space for molecules to pass through at same time
Why is a thin barrier a feature of a good exchange surface?
Reduces diffusion distance
Why is a good blood supply a feature of a good exchange surface?
Maintains steep conc grad of molecules so diffusion can raidly occur
S.A = 4πr²
V =
4/3πr³
What are spirometers used for?
Measuring lung volumes
How does a float chamber spirometer work?
During inspiration, air drawn from chamber so lid moves down. During expiration, air returns to chamber, raising lid. Movements recorded in data logger. CO2 rich air passed through soda lime chamber which absorbs the CO2 allowing measurement of O2 consumption
What precautions should be taken when using a spirometer?
Subject healthy and free from asthma
Soda lime fresh aand functioning
No air leaks in apparatus
Mouth piece sterilised
Water chambers not overfilled (would leak into tubes)
What does a peak flow meter measure?
Rate at which air can be expelled from the lungs
What’s the inspiratory reserve volume?
Vol of extra air we breathe in by breathing deeper
What’s the expiratory reserve volume?
Vol of extra air we can exhale after normal expiration
What does total lung vol consist of?
Vital capacity and tidal vol
Can vital capacity be measured using a spirometer?
Vital capacity =
Tidal vol + IRV + ERV
How is vital capacity measured?
Taking deep breathe and expiring all air poss from lungs
Can residual volume be measured using a spirometer?
What does vital capacity depend on?
Size of person (particularly height)
Age
Gender
Level of regular exercise
What’s tidal volume?
Vol air moved in and out during one ventilation cycle
Why does the overall vol of gas in the tank decline over time?
Spirometer contains soda lime which absrobs CO2
When breathing, using up O2 from tank while CO2 we breathe out is absorbed by soda lime
As result, vol O2 decreases over time
Decreases by vol of O2 used up by participant
What does breathing do?
Supplies O2 for resp and removes CO2 produced in resp
What happens as person breathes from spirometer?
O2 absorbed by blood and replaced by CO2
Why can we calculate the rate of O2 uptake using a spirometer?
Can measure gradient of decrease in vol as can assume vol of CO2 released and absorbed by soda lime is equal to vol of O2 absorbed by blood
What do we breathe in under normal conditions?
Air
What do we breathe out under normal conditions?
Air rich in CO2
How can breathing rate be calcuated from a spirometer trace?
Counting number of peaks in each minute
Avg breathing rate at rest
12-14
What will increase O2 uptake?
Increased breathing rate
Deeper breaths
How do you calculate O2 uptake from a spirometer trace?
Draw line from axis to point a and axis to point b
Measure length time between points
Measure difference in vol between points
Rate = vol/time
Where is the pharynx found?
Back of throat
What does the larynx do?
Connects pharynx and trachea
Voicebox
What’s the function of the epiglottis?
Stops blood entering trachea when swallowing
What type of epithelium lines the trachea, bronchi and bronchioles?
Ciliated
What does the trachea consist of?
Connective tissue
Elastic fibres
Cartilage
What do the bronchioles consist of?
Smooth muscle
Which lung is slightly smaller and why?
Left to make room for heart
Smooth muscle can _
Contract
What does the action of smooth muscle in the airway do?
Constricts airway making lumen of airway smaller which restricts flow of air to and from alveoli
When is controlling flow of air in airway important?
If harmful substances in air
Contraction of smooth muscle and control of airflow in airway is
When may contraction of smooth muscle in the airway occur?
As result of allergic reaction
What happens when smooth muscle in airway contracts?
Deforms the elastic fibres
How does the airway dilate after being constricted?
Smooth muscle relaxes and elastic fibres recoil to origional size and shape
What causes asthma?
Bronchioles constrict unnecessarily due to reacting with substances in the air
What’s alveoli comprised of?
Squamous epithelium
What are the alveoli surrounded by and why?
Blood caps so short diffusion distance
What do the alveolus walls contain and why?
Elastic fibres - stretch during inspiration then recoil to push air out during expiration
Are the alveolus walls thin or thick?
Thin
To be effective, airways must be:
large enough to allow sufficient airflow without obstruction
supported to prevent collapse when air pressure low during inspiration
flexible to allow movement
What are the airways lined with?
Ciliated epithelium
Where are goblet clells found?
Epithelium of airways
What do goblet cells do?
Release mucus to trap pathogens
What does cilia do?
Move mucus to top of airway to be swallowed
What does glandular tissue do?
Produce mucus
What are the trachea and bronchus supported by and why?
Rings of cartilage - prevent collapse during inspiration
What shape are the rings of cartilage in the trachea and why?
C-shaped - allows flexibility and space for food to pass down oesophagus
Which is narrower?
What are the walls of the bronchioles comprised of?
Elastic fibres and smooth muscle
Total lung capacity
Tidal vol
Inspiratory reserve vol
Expiratory reserve vol
Residual vol
Vital capacity
Last changeda year ago
