3.1 Exchange surfaces Flashcards
Why is diffusion alone enough to support single celled organisms?
Metabolic activity is low
Large surface area to volume ratio
How is surface area to volume ratio calculated
Surface area : Volume
Surface area/ volume : 1
What is the surface area of a sphere
4πr²
What is the volume of a sphere
4/3πr3
What happens to surface area to volume ratio and diffusion distance as the size of an organism increases
Surface area to volume ratio decreases, and diffusion distance increases
What is an exchange surface
Where diffusion occurs
What are the four adaptations of an exchange surface
Increased surface area, Thin layers, Good blood supply, Ventilation
How does increased surface area increase diffusion rate
Overcomes limitations of SA:V ration
What is an example of an increased surface area
Root hair cells in plants
How does once cell thick layers increase diffusion rate
Decreased diffusion distance, fast and efficient
What is an example of one cell thick tissue
Squamous epithelium, in the alveoli, lungs
How does good blood supply increase diffusion rate
Substances are constantly delivered and removed from the exchange surface, maintaining a steep concentration gradient
What is an example of a good blood supply
Alveoli in the lungs
How does ventilation increase diffusion rate
Maintain a concentration gradient, as gas is constantly supplied and removed
What is two examples of good ventilation in animals
Alveoli in lungs, gills of a fish
What happens to gasses in mammals before they are able to diffuse into the blood
Oxygen dissolves in water on gas exchange surface
What are conditions like in mammalian lungs, why is this?
Moist, allows for oxygen to dissolve into water before diffusing into blood. Conditions are ideal for evaporation of water and gas exchange
Why do humans need to have a gaseous exchange system
Small surface area to volume ration, high metabolic rate (active, maintain temperature
What is the gaseous exchange system in humans
Need oxygen for cellular respiration, produce carbon dioxide which needs to be removed
Where does gaseous exchange occur in humans
In the lungs, at alveoli
Recite the path of air going into lungs
Mouth, trachea, bronchus, bronchioles, alveoli.
Why is the nasal cavity important?
Large surface area with good blood supply - warms air to body temperature
Hairy lining - secrets mucus to trap dust and bacteria, protecting the lungs
Moist surface - Increases humidity of air, reducing evaporation from exchange surface
What is the trachea
Main airway
What tissues are found in the trachea
Ciliated Epithelium, Cartilage, Elastic fibres, Smooth muscle
What is the role of cartilage
Supports the trachea and prevents from collapsing when pressure drops
What shape is the cartilage in the trachea, why?
C shaped rings (incomplete) - allow food to move down oesophagus
What is the job of goblet cells
Secrete mucus, to trap dust and pathogens
What is the job of ciliated epithelium cells
Waft mucus away from the lungs to the throat, where it is swallowed and digested
What is the impact of smoking on the ciliated epithelium
Stops cilia being able to waft mucus
What is the role of elastic fibres
Stretch and recoil, forcing air out at the end of breath
What is the role of smooth muscle
Contracts and relax, changing the diameter of the trachea, altering air flow. Relaxed = wider.
What is the Bronchus (singular)/ bronchi (plural)
Trachea divides to form left and right bronchus, smaller then the trachea
What tissues are found in the bronchi
Ciliated epithelium, cartilage, elastic fibres, smooth muscle
What shape is cartilage in the bronchi
Irregular blocks
What is the bronchioles
Bronchi divide to form many bronchioles
What tissues are found in the bronchioles
Ciliated epithelium, Elastic fibres, smooth muscle,
What is the alveolus (singular)/alveoli (plural)
tiny air sacs where gas exchange occurs
What tissues are found in the alveoli
Squamous epithelium, Elastic fibres
What is the role of squamous epithelium
One cell thick, creating a short diffusion distance, allowing for efficient gas exchange
Why are elastic fibres important, especially in the alveoli
Allows for stretch and recoil, when gas enters, alveoli expand, when gas leaves it returns to the original shape
How are goblet cells distinguishable under a microscope?
Have circles with outer casing, surrounded by ciliated epithelium
How are ciliated epithelium distinguishable under a microscope?
Many hair like projections
How are squamous epithelium distinguishable under a microscope
One cell think
How are cartilage distinguishable under a microscope?
Looks like eyes
How are Elastic fibres distinguishable under a microscope?
stringy
How are smooth muscle distinguishable under a microscope?
uniform, spindle shapes
What are the four adaptations of alveoli?
large surface area - many hundreds of millions of alveoli in an adult lungs
One cell thick (squamous epithelium) - short diffusion distance
Good blood supply - maintains a steep concentration gradient
Good ventilation - maintains a steep concentration
What is the movement of air through the lungs called
Ventilation
What is the use of the ribs
Protect organs inside
Where are intercoastal muscles found
Between the ribs
What is the diaphragm
A broad, domed sheet of muscle, forming the floor of the thorax
Where are pleural membranes found
surrounding the lungs
What is the space between the lungs called
pleural cavity, filled with lubricating fluid, so membranes can slide as you breathe
What is inspiration, is it energy requiring?
Taking in air, energy using process
What happens during inspiration
Diagram contracts and flattens, intercostal muscles contract, moving the ribs up and out, increasing the volume of the thorax, so pressure is reduced, to below atmospheric pressure, so air is forced into the lungs
What is expiration, is it energy requiring?
Breathing out, passive process
What happens during expiration
Diagram relaxes, becoming dome shaped, intercostal muscles relax, ribs move down and inwards, elastic fibres in alveoli return to normal length, volume of thorax decreases, increasing pressure to above atmospheric pressure, so air move out of lungs until equilibrium is reached
What is asthma?
A condition that has airways that are sensitive to triggers
What happens during an asthma attack
cell lining in the bronchioles release histamines, inflaming epithelial cells, overstimulating goblet cells, and contracting smooth muscles.
Airways are narrow and filled with mucus
What are the two was to treat asthma
Relievers, attach to active sites on membranes, relaxing muscles
Preventors - steroids that reduce sensitivity of the lining
How is a babies first breath possible
First breath is the hardest.
Lung surfactants, stops alveoli from collapsing and sticking together
What is a peak flow meter
measures rate at which air an be expelled from the lungs
What is a vitalographs
Patient breathes out as quicky as possible, instrument produces a graph, measuring the forced expiratory volume in one second
What does a spirometer measure
Aspects of lung volume, investigate breathing patterns
What is the tidal volume
Volume of air moving in and out of lungs which each resting breath (average)
What is vital capacity
Voulme of air that can be breathed in and out, strongest exhalation and deepest intake
What is inspiratory reserve volume
maximum volume of air that can be breathed in - normal inhalation
What is expiratory reserve volume
Extra volume of air in the lungs that could be forced out after a breath
What is the residual volume
Volume of air left in the lungs when you have exhaled as hard as possible
What is the total lung capacity?
sum of the vital capacity and residual volume
What is the breathing rate
Number of breaths per minute
What is the ventilation rate
total volume of air inhaled in a minute
VR = tidal volume x breathing rate
What happens to tidal volume and breathing rate as exercise is increased
increases
Why do plants have a different gaseous exchange system to humans
Have a tough exoskeleton, where no gas exchange can occur, oxygen is delivered directly into cells.
How does gas exchange occur in insects?
Air enters through spiracles (small openings). air then enters the tracheae, which then divides into tracheoles, oxygen then dissolves in moisture on the walls, and diffuses into the cell
How is gas exchange in insects made more efficient
Spiracles can open and close to prevent water loss.
When oxygen demands are low, spiracles are closed, when carbon dioxide levels raise, or demand increases, they open
Where is tracheal fluid found?
towards the end of tracheoles
What job does tracheal fluid serve
Limits oxygen diffusion. When oxygen demands increase, fluid moves out of the tracheoles, increasing diffusion
How many some larger insects get extra oxygen?
mechanical ventilation
Collapsible enlarged tracheae or air sacs
What is mechanical ventilation
Air is actively pumped into the system via muscles in the thorax and/or abdomen, changing the volume and pressure in the trachea and tracheoles
What is collapsible enlarged trachea or air sacs
increasing the amount of air moved
Why do fish need specialised respiratory systems
Viscosity of water and lower oxygen content, leading too slower rate of diffusion
What is the gaseous exchange system in fish
Gills
What are the adaptations of gills
Large surface area, good blood supple, thin layers
What is the gill filaments
Occur in large stacks - gill plates.
large surface area for gaseous exchange. Fan out when in water to increase surface area
What are the gill lamellae
Bumps on the gill filament which increases surface area
What is the operculum
The flap that covers the gill
What do most fish rely on for gills to work, what is this called
Constant flow of water
Ram ventilation
How do bony fish do diffusion while not having a constant flow of water
Mouth is opened and the floor of buccal cavity is lowered. increasing the volume and decreasing the pressure. This forces water into the mouth. Floor of buccal cavity moves up, increasing pressure, and decreasing volume, forcing water over the gills, the mouth closes, operculum opens, maintaining a constant flow of water over the gills
What happens to the gill filaments when water runs over them
They fan out, increasing surface area
What are some things that make gaseous exchange in bony fish effective
Tips of adjacent gill filaments overlap, increasing resistance to water, decreasing speed of water, increasing time for diffusion
Counter current exchange system, water flows over gills in one direction, blood flows the other way. Creating steep concentration gradient, as when oxygen diffuses into gills, it is immediately transported by the blood
Large surface areas, Hundreds of gill filaments, Lamella, Gills fan out in water
