Topic 6: Exchange with the environment Flashcards
What three things affect rate of diffusion
- SA:V ratio
- Concentration gradient
- Diffusion Distance
Why do larger organisms need more exchange adaptations
They have (typically) a higher metabolic rate, so they need to transport waste material away efficiently
What is Ficks Law
Equation
Rate of diffusion = (SA x Conc. Gradient) / distance
What does Ficks Law state
That any exchange surface will have:
- A Large Surface Area
- A mechanism to maintain conc. gradient
- Short diffusion pathway
Villi and Microvilli
What is it and what mechanism its found in
What
Folds in the walls of an exchange surface and extensions in individual cells on those surfaces
Where
Absorption of digested foods
Alveoli and Bronchioles
What is it and what mechanism its found in
What
Air sacs at the end of the bronchioles and small airway passges
*Where *
Gas Exchange
Spiracles and Tracheoles
What is it and what mechanism its found in
What
Respiratory openings on the thorax and abdomen on insects to control air flow and small airway passages
Where
Gas Exchange
Gill filaments and Lamellae
What is it and what mechanism its found in
What
A tissue on a fish where gas exchange occurs and flaps on these structures to increase surface area
Where
Gas exchange
Thin, Wide leaves
What is it and what mechanism its found in
Where
In Plants
What
Gas exchange
Capillary network
What is it and what mechanism its found in
What
Many tint blood vessels that surround exchange surfaces to maintain a gradient
Where
Gas exchange
What is the exoskeleton on insects made of and why
Chitin, for protection
Lipid Layer, to prevent water loss
What do insects have instead of lungs
Tracheal system
Why do insects need gas exchange surfaces
Water evaporates off the surface of terrestial insects,
Adaptations of gas exchange prove ideal conditions for evaporation
What are the structures part of the tracheal systems
- Spiracles
- Trachea
- Tracheoles
What are Spiracles?
Round, valve like openings
Where are the spiracles located
They run along the length of the abdomen
What enters and leaves via the spiracles
Oxygen and Carbon dioxide
What are the trachea
Network of internal tubes
Why do the trachea have rings within them
- To strengthen the tubes
- To keep them open
What does the trachea branch into
Tracheoles
Where do you find the tracheoles
deeper in the abdomen
Where do the tracheoles extend to
All tissues in the insect
What is the purpose of the tracheoles
To deliver oxygen to all respiring cells
What are the three methods of moving gas in the tracheal system
- Diffusion
- Mass Transport
- Osmosis
How does gas exchange occur by diffusion in the tracheal system?
- Cell respiration uses up O2 and produces CO2.
- Creates concentration gradient from tracheoles to atmosphere
How does gas exchange occur by Mass Transport in the tracheal system?
- Insect contracts and relaxes its muscles to move gases in larg amounts
How does gas exchange occur by Osmosis in the tracheal system?
- Insect in flight respires anaerobically
- Produces lactate
- Lowers water potential of cells
- Water moves into cells via osmosis
- Decreases pressure in the tracheoles
- draws more air from the atmosphere
When will gas exchange by osmosis be facillitated?
When the insect is in flight
Name the three adaptations of the tracheal system
- Large SA:V
- Short Diffusion Pathway
- Maintained conc gradientt
What is the example of a large surface area in the trahceal system
Large abundance of find tracheoles
How is short diffusion pathway implemented in the tracheal system
Walls of tracheoles are thin
Distance between spiracles on the outside, and tracheoles on the inside is short
How is a maintained conc gradient implemented in the tracheal system
Use of oxygen and production of CO2 creates steep conc gradient
What prevents gas exchange across the surface of fish bodies
Their scales making them waterproof
What structure do fish have for gas exchange?
Gills
What is fish’ SA:V
Small / large
Small
How do fish obtain oxygen
From water
How many layers are there on fish gills
Four layers
What do you call each layer of the gill
Gill filament
What is each gill filament covered in
Lamellae
How are the lamellae positioned on the gill filament
Adjacent to the gill filament (right angles)
Why do fish have lamellae
To increase surface area
Where does diffusion of oxygen in fish occur
On the lamellae
How do fish obtain oxygen
- water enters through mouth
- rushes over gills where oxygen diffuses in lamellae
- out through a gap in the side of the fish head
What is countercurrent exchange?
Countercurrent is when the water flows over the gills, in the opposite direction to the flow of blood in the capillaries
Why do fish need countercurrent exchange?
- ensures the concentration gradient is maintianed across the entire length of gill lamellae
- equillibrium of oxygen conc. never reached
State and explain the three adaptations do fish have for gaseous exchange?
- Short diffusion distance
A capillary network within each gill lamellae - Large SA:V
Four gills. stacks of filaments, covered in lamellae - Maintain conc. gradient
Countercurrent flow mechanism
Name the main structures of the dicotyledonous leaf
- Waxy cuticle
- Upper / Lower Epidermis
- Spongy Mesophyll
- Palisade Mesophyll
- Stomata + Guard cells
Where does gas exchange happen in leaves
Through the stomata on the bottom sides of leaves
Explain Gas exchange in leaves
- gas diffuses through the stomata on bottom of leaves
- CO2 diffuses into spongy mesophyll
- Spongy mesophyll has ots of space, creates conc. gradient
- CO2 diffuses up towards the palisade mesophyll
Name and explain three adaptations of leaves for gas exchange
- Large SA:V
Wide and thin, spongy mesophyll has large sa - Short diffusion pathway
Many stomata, every living cell is close to external air and source of oxygen - Maintained conc. gradient
CO2 and O2 create steep conc. gradient
What strcture on the leaf is responsible for reducing water loss
Stomata (controlled by guard cells)
How do the stomata reduce water loss by evaporation
- Guard cells shrink
- Stomata close at night
- because photosynthesis is slows and stops
What is a xerophytic plant
Adapted to survive in environments with limited water, with features that minimise water loss and maximise efficient gas exchange
What are the 5 adaptations of xerophtes
- Curled leaves
- Hairs
- Stomata are sunken in folds
- Thicker cuticle
- Longer root network
How do curled leaves help xerophytic plants
- Trap evaporated water
- Increase local humdidity
- Reduced conc. gradient
How do Hairs help xerophytic plants
Trap moisture to increase local humidity
How do sunked stomata help xerophytic plants
- stomata sunken in folds
- trap moisture
- increase local humdidty
How does a thicker cuticle help xerophytic plants
Reduces evaporation
How do long root networks help xerophytic plants
Allows them to reach for more water
Define respiration
Chemical reaction that releases energy int eh form of ATP
(In order), state the pathway of air
Trachea
Bronchi
Bronchioles
Alveoli
What allows the trachea to expand and contract during ventilation
C-shaped cartilage rings
Why are th Cartilage rings important for the trachea
- Support the trachea
- Prevent it from collapsing as you exhale and pressure decreases
State and explain the adaptations of the alveoli
- Large SA:V
Millions of alveoli - Short diffusion pathway
Capillaries and epithelia of alveoli are 1 cell thick - Maintained conc. gradient
Capillary network carries oxygen away from lungs and CO2 towards the lungs
How does the capillaries being one cell thick maximise gas exchange
- RBC are slowed as they pass through
- Diffusion distance minimised
- Distance between alveoli air and RBC is reduced
What are the two main muscles involved with Ventilation
- Diaphragm
- Internal / External intercostal muscles
What are the internal and external intercostal muscles
Antagonistic pair
Explain Inspiration (Inhalation)
- External intercostals contract, internal intercostals relax
- Rib cage moves up and out
- Diaphragm contracts, moves down
- Increases volume
- Lowers pressure
- Air rushes into lungs
Explain Expiration (Exhalation)
- Internal intercostals contract, external intercostals relax
- Rib cage moves down and in
- Diaphragm relaxes back to dome shape
- Decreased volume, increased pressure
- Air rushes out
Define tidal volume
The amunt of air that is moved into or out of the lungs in a given time
Define pulmonary ventilation rate
Total volume of air that is moved into the lungs in one minute
What is the equation for pulmonary ventilation rate
Pulmonary ventilation rate = tidal volume x breathing rate
What is a spirometer
- Instrument used to measure lung capacity
- You blow out into it as much as you can with a nose plug on
How does bronchitis affect gas exchange
- Inflammation of bronchioles
- mucus production decreases air flow
- deccreases amount of oxygen entering
- decreases amount of CO2 leaving
- minimises the conc. gradient
- minimises gas exchange
What is asthma
- Chronic condition
- Inflammation of the airways
- Produces mucus
- decreases air flow
What is pulmonary fibrosis
- Scarring of the lungs
- damages alveoli
- thickens walls of tissue
- decreases sa
- reduces gas exchange
What two main enzymes digest carbohydrates
- Salivary amylase
- Membrane bound disaccharidases
Describe digestion of carbohydrates
- Salivary amylase hydrolyses polysaccharides into disacchardie maltose, via hydrolysis of glycosidic bonds
- Travels to duodenum, which recieves enzymes via ducts from the pancrease
- In duodenum and ileum, membrane bound disaccharidases hydrolyse disaccharides into monosaccharides
What are the disaccharides and their monosaccharides
and their disaccharidases
- Glucose + Glucose = Maltose
(maltase) - Glucose + Fructose = Sucrose
(sucrase) - Glucose + Galactose = Lactose
(lactase)
Name and explain the three enzymes that hydrolyse protiens
- Endopeptidases
Hydrolyses peptide bonds in the middle of polypeptide - Exopeptidases
Hydrolyses peptide bonds at the end of polypeptide chain - Membrane bound dipeptidases
Hydrolyse peptide bonds between two amino acids
Where does protien digestion start
In the stomach
