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Terms in this set (31)
Higher surface area to volume ratio means that there is more diffusion able to happen real-time to size.
Good for diffusion in organisms, heat dissipation, active transport.
Why is surface area to volume ratio important in organisms
We are large so O2 can't diffuse directly into lungs
Ensures blood can be medium for waste removal and nutrient transport etc
We are land borne - diffusion surfaces need to be moist for diffusion
Maintains large concentration of CO2 and O2
Why do we need a ventilation system?
The junction between the trachea and gullet
What is the pharynx?
Supported by cartilage rings to hold the tube open so air can pass through.
Muscle and cartilage rings
Flexible so it can expand to allow more air in
Rings in c shape and expand C
Describe the structure of the travhea
Violated epithelial cells - waft mucus which trap microbes and dust to ensure the air we breathe is clean
Goblet cells - produce mucus which line the trachea
Once microbes are trapped in mucus cilia waft it in upward to top of trachea so it can be swallowed (pathogens killed by stomach acid) or coughed out of body
What are the adaptations of the trachea
Similar to trachea - muscle and cartilage
+ inner walk contains ciliated epithelial and goblet cells
Describe the structure of the bronchi
Narrower areas - bronchi divide into bronchioles
Muscle walk can constrict to control air flow (not always good)
Lined with epithelial cells
Bronchioles join to alveoli - site of gas exchange
What do the bronchioles sounds and what is their structure
Large surface area
Capillary network - maintain conc gradient by removing and supplying O2/CO2
Very thing membranes - thin diffusion path
Walls of alveoli contain collagen and elastic fibres - stretch and shrink for exhalation and inhalation
How are alveoli adapted
Asthma - irritants and allergies
Tuberculosis - exposure to TB bacteria
Lung cancer - family history, exposure to asbestos / other carcinogens
Bronchitis - childhood respiratory diseases, asthma, allergies
Lung disease - exposure to asbestos, radon gas, chronic bronchitis, asthma, emphysema
Second hand smoke
Give examples of respiratory diseases and their risk favtors
Squamous epithelial cells - flat, so very thin. Short diffusion path
So thin that their nucleus creates bump in cell
How are the epithelial cells of the alveoli adapted
An airtight region formed by the rib she - housed by ribs and intercostal muscles
What is the thorax?
A sheet of muscle separating the thorax and the abdomen
What is the diaphragm
External intercostal muscles contract
Internal intercostal muscles relax
Volume is increased by ribs moving up and out
Diaphragm moves down - increase volume , lowers pressure (boyles law)
Air moves from high to low pressure
Air moves from atmosphere into lungs
What is the process of inhalation (inspiration)
Volume is decreased by internal intercostal
External intercostal muscles relax
Rob cage moves down and in
Diaphragm relaxes (moves up)
Decrease in volume - increased pressure - air forces out (boyles law)
What is the process of exhalation (expiration)
Look for patterns in data - correlation
To test wether correlation shows causation use experimental testing eg 1950s, dogs forced to smoked and studied effects - developed lung cancer
How do scientists identify disease risk factors
Something that increases the likelihood of developing a disease
What is a risk factor
Air travels in through spiracles
To tracheoles which deliver O2 directly to respiring tissues eg muscle tissues
How do insects do gas exchange
Rings of chitin
What is the structure of the trachae
Close in hot weather to prevent water loss.
- insect becomes less active because taking in less O2 for respiration
Under what conditions do spircales open and close. +what happens to activity of the insect
Cells in insects are always a short distance form tracheoles - if too large of a body diffusion path comes too long for effective diffusion. Cells can't take in enough O2 for cells to carry out functions eg aerobic respiration
Why are insects limited in how large they can be?
The contraction of abdominal muscles in insects can squeeze the trachae enabling mass movement of air in and out. - further speeds up exchange of respiratory gases.
In flight muscles work anaerobically , producing lactate. This lowers the water potential of the cells. (Tracheoles filled with water)
- causes water to move into the cells from tracheoles
- decreases volume of tracheoles
- more air from atmosphere drawn in
Means final diffusion pathway is gas rather than liquid base - diffusion is more rapid.
Increases rate air is moved into tracheoles and leads to greater water evaporation.
How do insects carry out mass transport. What happens in flight
Gill filaments are stacked in a pile
at right angle to the filaments are lamellae - increases surface area for gas exchange.
Counter current flow - maintains concentration gradient by constantly removing oxygenated blood and ensuring water flowing next to blood is always at a greater oxygen concentration than the blood.
Ensures maximum possible gas exchange.
Short diffusion path - 1 cell thick.
How is gas exchange in fish adapted + structure
Waxy cuticle (part of upper epidermis)
Sponges mesophyll (containing xylem and phloem and airspace)
^both = mesophyll
Lower epidermis (containing guard cells, stomata, waxy cuticle)
Name the layers of the leaf from top of the leaf to the bottom
Thin - short diffusion path
Chloroplasts - containing chlorophyll that absorbs light energy from sun
Can change direction - to face sunlight
Large surface area - more space for more chloroplasts, absorb more light
Waxy cuticle on top layer of leaf - reduce water loss from transpiration
Veins - transport water to leaf and glucose away from leaf
Many stomata - allow for gas exchange
Air space - gases diffuse faster through air than cells
What are the adaptions if a leaf and why
Stomata open to allow for gas exchange
Sensors in guard cells sense light
As light intensity increases, activate potassium pumps
Potassium moves into guard cells
Causes water to move in by osmosis
Guard cells change shape by gaining water by osmosis
Potassium decreases water potential in cell (hypotonic to outside cell)
Causes cell to become turgid - c shape - thick inner wall, expands more on outside where thin wall is.
Describe what happens to the stomata in the morning and hos
Closes to stop loss of water vapour. No gas exchange needed for photosynthesis
Potassium leaves cell by facilitated diffusion.
Water potential in cell increases - water moves out of cell by osmosis, regains original shape - flaccid
Describe what happens to the stomata at night and how?
A plant adapted to a dry habitat
Define a xerophyte
Leaves reduced to spikes - less water loss
Guard cells are sunk into the waxy cuticle - create local humidity, reduced diffusion gradient
waxy cuticle is thickened
What are the adaptations of cacti
Rolled leaves - stomata on inside within rolled leaves
Leaf hairs - local humidity next to leaf, decreases flow of air currents
What are the adaptations of marram grads
Small leaf surface area
Extensive roots - maximise H2O uptake
Thick waxy cuticle
What are (other) xerophyte adaptions
They are too large, their surface area to volume ratio is not great enough to take in enough O2 for enough aerobic respiration to provide their body with enough energy for movement and body functions
Also, diffusion path would b too great so would take too long
Why do multicellular organisms not do gas exchange through diffusion directly across their body surface like single called organisms
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