3 - Exchange and Transport Sytems Flashcards
What materials need to be exchanged
Oxygen , co2 ( respiratory gases)
Glucose, fatty acids, vitamins, minerals (nutrients)
Excretory products ( urea and co2)
Heat
What 2 ways can substance exchange take place
Passively ( diffusion / osmosis )
Actively ( active transport)
How do organisms evolve to meet the needs of SA:volume ration
Flattered shape so that no cell is ever to far away from the surface
Specialised exchange surface with larger areas to increases SA to volume ratio
Simple diffusion of materials across the surface can only meet needs of……
Relatively inactive organisms
Why are there Features of specialised exchange surface
To allow effective transfer of material across them by diffusion or activate transport
What are the features of specialised exchange surfaces
Large SA to VOL ration to increase. The rate rate of exchange
Very thin so diffusion distance is show and therefore crosses the exchange surface rapidly
Particallly permeable to allow selected material to cross without obstruction
Movement of environment medium eg, air to maintain gradient
How do you calculate rate of diffusion
Surface area x differnce in concentration
____________________________________________
Length of diffusion pathway
Where are exchange surfaces located usually and why
Inside
As easily damaged
Why do small organisms not need an exchange surface
Diffusion across their body surface is suffocating as the distances are short (less that 0.5mm)
Surface area is relatively large
Area of circle formula
Pi r ^2
Area of a square formula
B x h x l
area of a sphere
4/3 pi r ^3
Surface area of a sphere
4pi r ^2
What do large organisms do to meet demands of O2 / minerals
A specialised exchange surface
What 3 ways does gas exchange happen in insect s
1) along a diffusion gradient
2) muscle contraction
3) using water potentials
How does gas exchange age in insects a long a diffusion gradient
conc of oxygen decreases along a tracheol
Causes diffusion gradient between atmosphereic O2 and cells
CO2 works in the opposite direction as cells respire
Is diffusion quicker in air or water
Air
How does gas exchange in insects
( contraction of muscle )
Mass transport
Contraction of muscles in an insect squeeze air in and out which speeds up exchange
How does gas exchange in insects
( water potential)
The ends of the tradheoles are filled with water
During active periods, muscle cells around tracheoles carry out aerobic respiration
Produces lactate which us soluble thus lowers water potential of the muscle cells
Water therfore move into cells from the tracheoles by osmosis. The water in the end of the tracheoles decrease in volume thus increasing the amount of water which may fit in
If you increase air into the tracheoles in an insect what does it lead to
Greater evaporation of water
How can you reduce water loss from insects
Hairs whichh trap water
The spiricles close most of the time
What are spiracles
Pores at the end of tracheoles om surface of insect
They can open and close by valves
What can happen when spiracles are open
Water Vapor can evaporate so insects may have them closed
Why do spiracles open periodically
To allow gas exchange
What are the similarities between stomata and spiricles
Open and close to reduce water loss
Positioned on the outside of the organism
Differences of spiracles and stomata
Spiracles have valves
Stomata have guard cells
Limitations of insects
Relies a lot on diffusion
Requiring a short diffusion pathway
The insect therefor has to be relative,y small
(Super hornets defy this)
what does photosynthesis use and release
Use co2
Release O2
What gases dowm respiration requires and which gas is released
Requires O2
Releases CO2
What reduces gas exchange with external air
In plants
At time gases for, one process can be used by the other
(respiration and photosynthesis)
Where does most of the O2 go from photosynthesis in plants and where does some go
Most diffuses out of lease but some used in respiration
Describe how gasses move out of leaves
Diffusion in the gaseous phase ( more rapid than in water )
No living cell is far from external air + therfore sources of O2 and CO2
short diffusion pathway, air spaces to provide very large Sa:V of loving tissues
Is there any specific transport system for gases in plants.
No there are just adaptations that cause raid diffusion
How does a leaf have a short diffusion pathway
As no cell is far away from the stomata
As airspace’s interconnect cells
Adaptations in plants for rapid diffusion
Shot diffuion pathway
Large SA od mesophyll cell for rapid diffusion
Where are the stomata located
Underside of leaves
What are stomata surrounded by
Guard cells
Which open and close the stomata pore
What do guard cells do
Control the rate of gaseous exchange and prevent loss of too much water by evaporation
What are the layers of a leaf blade
Waxy cuticle
Upper epidermis
Palisade layer }
Air spaces } spongy mesophyll
Lower epidermis }
What are phloem and xylem known as
Vascular bundle
What does the phloem transport
Sucrose + minerals
What does the xylem transport
Water + minerals
How many times denser us water than air and with what fraction of O2
1000 times denser with 1/30th the O2
How many time more viscous than air is water
100x
For fish Moving water in and out under water would use too much energy So what do they do
Only in one direction in counter current with bloof
Counter current flow maintains a favourable conc. gradient across the entire exchange surface
How do fish obtain the oxygen needed form the water
By the gills
As water flows of the bill surface respiratory gases are each edged between the blood and water
As % of dissolved oxygen in water is much less than air there are high rate of oxygen extraction form water
T or f
Fish have a closed circulatory system
Yes
What does it mean that fish have a closed circulatory system
The blood is entirely contained within the vessel
Do fish have a double circuit system
No single
What is a gill cover called
Operculum
What is inspiration
Mouth open
What is expiration in fish
Mouth closed
Describe fish gills
Many folded which are supported and kept apart for each other by the water
This gives them a high SA
How does gas exchange occur in fish
Diffusion vetween the water and blood across the gill memebrane and capillaries
The operculum permits exit of water and acts as a pump
Describe inspiration in fish
Oral valve opened
Mouth cavity expands taking in water through open mouth
Operculum is closed and moved outwards to assist water intake
Descirbe expiration in fish
Oral valve shirt s
Mouth cavity contracts forces water back across the gills
Operculum is open
What is rhe bony bar in fish called
Branchial arch
Describe how gas exchange rate in fish is optimised
A constant steam of oxygen rich water flows over the gill filaments in the opposite direction to the direction of blood flow through the gills. This is called counter current flow
Blood flowing through the fill capillaries Will encounter water of increase ot oxygen content , so the conc gradient for O2 across the grill is manintian across the entire distance of the hill lamella
What would happen if fish exchanged gas is parallel current flow
Wouldn’t achieve the same oxygen extraction r stem as conc across frill would quickly equalise
What vessel takes blood away form the bill
Efferent vessel
What vessel brings deoxygenated blood to the gill
Afferent vessel
What are gill plates
Folds in lamellase
Single cell layer
It’s the Exchange surface
What is the thickest part of the stomatal cell
Inner wall
What is the type of plant derived form a seed which contains two cotyledons
Dicotyledonous
What needs to be exchanged within the environment in an organism
Oxygen and nutrients
Waste products, co2 urea
Heat
How easy the exchange of substances depends on what
the organisms surface area to volume ratio
In single celled organisms how do substances exchange
And how fast
Can diffuse directly out of or into the cell across the cell surface membrane.
Diffusion rate is quick becuase of the small distance the substance have to travel
How does a single felled organism exchange surface and how fast
Diffuse directly across the cell surface membrane
Diffusion rate is quick becuase of the small distance
In multicellular animals why is diffusion across the outer membrane too slow
Some cells are deep within the body (there is a large distance between them and the outside environment)
Larger animals have a low surface area to volume ratio. It’s difficult to exchange enough substances to supply a large volume of animal through a relatively small outer surface
How do multicellular organism exchange substances
Exchange organs
Mass transport (eg, blood to carry glucose and O2, and I o ants water and solutes)
What 2 things does the rate of heat loss depend on
Shape and Size
Why does the rate of heat loss depend on surface area
Is an organism has a large volume it’s SA is relatively small, this makes it harder for it to lose heat from its body, if an organism is small is has a relatively large SA so heat is lost more easily. This means smaller organisms need a relatively high metabolic rate in order to generate enough heat to stay warm
How does shape effect rate of heat loss
Animals with a compact shape have a small surface area relative to their volume ratio - minimising heat loss form the surface
Animals weight less compact shape have a larger surface area relative to volume thus increases heat loss form the surface
Weather an animal is compact or not depends on the temp of the environment
Animals with hight surface area to volume ration tend to lose more water. How have some small desert mammals adapted
Kidney structure adaptations so they they produce less urine to compensate
To support their high metabolic rates what to small mammals livening in cold regions do
Need to eat large amounts of high energy food such as seeds or nuts
What adaptations do small mammals have when weather gets could
Thick layers of fur
or hibernate
How have larger organisms libing in hot regions adapted
Eg,
Elephants lathe flat ears to increase Sa to vol rayon
Hippos spend most day in water (behavioural adaptation)
What are Xerophytes
+ examples
Plants with are adapted to survive in very dry conditions
Marram grass / cacti
Feature or marram grass
Lives on Sandy ground where there is little water + may be very salty
Thick cuticle to reduce water loss
Stomata in pits
Pits surrounded by hairs, there trap layers of moisture outside stomata reducing diffusion gradient so less water is lost in transpiration
What are hinge cells
Allows leaf of marram grass to roll up when short of water so that stomata are not exposed to wind or dry air
What are some general features of xerophytes
Long shallow spread our roots
Swollen succulent stem
Leaves reduced to spikes
Round shape
Hairs on surface to reflect light
Why do xerophytes have long shallow spread out roots
Absorbs more water
Why do xerophytic plants have swollen succulent stem
To retain water
Why do xerophytic plants have leaves reduces to spikes
To reduce water loss ( as reducing SA to volume ration)
Why do xerophytic plants have leaves reduces to spikes
To reduce water loss ( as reducing SA to volume ration)
Why do xerophytic plants have round shape
Reduces SA to volume ratio
What do most exchange surfaces have in commmen
Large surface area
Thin
steep conc. gradient
Explain gass exchange in fish
Water, containing oxygen, enters the fish through its mouth and passes out through the gills.
2) Each gill is made of lots of thin plates called gill filaments,
which give a big surface area for exchange of gases.
3) The gill filaments are covered in lots of tiny structures called
lamella
(plural = lamellae)
lamellae, which increase the surface area even more.
4) The lamellae have lots of blood capillaries and a thin surface layer of cells to speed up diffusion.
5) blood flows through the lamellae in one direction and water flows in the opposite direction. This is called a counter current system. It maintains a large conc gradient between water and the blood. Thus conc of oxygen in the water is always high than in the blood so as much oxygen as possible diffuses form the water into the blood
Insects have microscopic air filled pipes called what?
Tracheae
Describe gas exchange in insects
Air moves into the tracheae through pores called spiracles
Oxygen travels down the conc gradient towards the cells
The tracheae branch off into smaller tracheoles which have thin permeable walls and go to individual cells. This means that oxygen diffuses directly into the respiring cells.
Carbon dioxide for the cells move down its own conc gradient gradient towards the spiracles to be released into the atmosphere
Insects use rhythmic abdominal movements to move air in and out of spiracles
What gases are needed in plants and why
CO2 FOR photosynthesis
o2 for respiration
What is the main gas exchange surface for dicotydonous plants
Mesophyll cells
What are th spores in the epidermis of the leaf called
Stomata
(Singular stoma )
How are you mesophyll cells adapted for their function
Larger SA
What controls the opening and closing of the stomata
Guard cells
How do insects minimise water loss
Close their spiracles using muscles
Also waterproof waxy cuticles all over their body and tiny hairs aorund their spiracles, both which reduce evaporation
How does water levels effect the opening or closing of stomata
Water enetrees the guar d cells making them turgid which opens the stomatal pore.
If a plant gets dehydrated the guard cells lose water and become flaccid which closes the pore
What are xerophytes
Plants adapted for life in warm dry windy habitats where water loss is a problem
What are some xerophytic adaptations
Stomata sunk in pits that trap moist air, reducing the concentration gradient of water between the leaf and the air. This reduces the amount of water diffusing out of the leaf and evaporating away.
• A layer of ‘hairs’ on the epidermis — again to trap moist air round the stomata.
• Curled leaves with the stomata inside, protecting them from wind (windy conditions increase the rate of diffusion and evaporation).
• Areduced number of stomata, so there are fewer places for water to escapes.
• Wary, waterproof cuticles on leaves and stems to reduce evaporation.
What must a gas exchange surface be like
Thin
Large SA
constantly ventilated
any factor that effects a gas exchange surface will effect what
Efficiency of gas exchange
Why do we need a breathing system
-all aerobic organisms require constant O2 to release ATP
- Build up of co2 - toxic to body (as acidic and can cause harm to enzyme action / organelles) - -volume O2 needed and vol ifCO2 removed is greater than that can be delt with by diffusion alone
- mammals also need to maintain body temp + have high metabolic c respiratory rates
Where are the lungs loacted in humans
In thorax protected by rib cage
Why can’t lungs exits outside the body
Air is not dense enough to support and protect the delicate structures
They would also dry out if outside the body
What is pulmonary ventilation
Total volume of air moved into the lung in one minute
Pulmonary ventilation calculation
Pulmonary ventilation = tidal volume X ventilation rate
What is tidal volume
Volume of air normally taken in at each breath when the body is at rest
What is tidal volume usually around
5dm-3
What is ventilation rate
The number of breaths taken in one muinet
What is ventilation rate normally
12-20 breaths in healthy adult
Units for ventilation rate
Dm3 min-1
Describe inspiration
The external intercostal muscles contract, while internal intercostal muscles relax
The ribs are pulled upwards and outwards, increasing the volume of the thorax
Diaphragm muscles contract, causing it to flattern, also increases the volume of the thorax
The increased volume of the thorax results in reduction of pressure in the lungs
Atmospheric pressure is now greater than pulmonary pressure, and so air s forced into the lungs
Describe expiration
The internal intercostal muscles contract, external intercostal muscles relax
Ribs move down and in, decreasing thorax volume
diaphragm muscles relax, returns to its upwardly domes position, decreasing volume of thorax
Decreased volume of thorax in cereals pressure in lungs
Pulmonary pressure is now greater that that of the atmosphere and so air is forced out of the lungs
Explain how air gets to the alveoli
as you breathe in air enters the trachea
The trachea splits into two bronchi - one bronchus leading to each lung
Each bronchioles then branched off into smaller tubes called bronchioles
The bronchioles end in small ‘air sacs’ called alveoli
What does ventilation consist of
Inspiration
Expiration
Is inspiration active or passive
Active
Is expirationactive or passive
Passive
Can expiration be forced
Yes
What happens during forced expiration
External intercostal muscles relax and inter costal muscles contract, pulling the rib cage further down and in
during this time , the movement of the two sets of intercostal muscles is said to be antagonistic
What is each alveolus made from
Single layer of thin , flat cells called alveolar epithelium
What are alveoli surrounded by
Network of capillaries
Descirbe gas exchange in the alveoli
O2 diffused out of the alveolu across the alveolar equilibrium m and into haemoglobin in the blood
Co2 diffuses into the alveoli from, the blood and is breathed out
Alveoli adaptation for gas exchange
Thin - short diffusion pathway
Large SA
Steel conc gradient - maintained by the flow of blood and ventilation
What is forced expiratory volume (FEV)
The maximum volume of air that can be breathed out in 1 second
What js forced vital capacity (FVC)
Maximum volume of air it is possible to breathe forcefully out of the lungs after a deep breath in
How can you figure out tidal volume, ventilation rate
Spirometer
How does TB effect the lungs
When someone becomes affected with tuberculosis bacteria, the immune system cells build a wall around the bacteria in the lungs. This form small, hard lumps known as tubercles
Infected tissue within the tubercles die and the gas is exchange surfaces damaged so tidlevolume is decreased
Reduce tide avoid means less can be inhaled at each breath so in order to take enough oxygen, they have to breathe faster so ventilation rate is increased .
Common symptoms therefore include persistent cough , coughing up blood and mucus, chest pains, shortness of breath and fatigue
How does fibrosis affect the lungs?
Fibrosis is the formation of scar tissue in the lungs. This can be result of infection exposure to a substance like asbestos or dust.
Scott tissue was thicker less elastic than normal lung tissue
Means lungs are less able to expand them so can’t hold as much air as normal so tidle volume is reduced There is a reduction in rate of gas exchange and diffusion slow across a thicker scarred membrane.
Symptoms include shortness of breath, dry cough, chest, pain, fatigue, and weakness
How does asthma affect the lungs?
Asthma is respiratory condition where airways become inflamed and irritated
During an asthma attack, the smooth muscle lining of the bronchioles contracts and a large amount of mucus is produced. This causes construction of the airways, making it difficult to breathe airflow in and out of the lungs is reduced so less oxygen enters the alveoli and moves into the blood reduced airflow means the forced expiratory volume is reduced Symptoms include wheezing, tight chest and shortness of breath
What is the effect of emphysema on the lungs
Emphysema is a lung disease caused by smoking and long-term exposure to air pollution. This causes inflammation, which tracks phagosites the area the phaosites producd anenzyme that breaks down the elastin, which is a protein found in the wars of the alveoli elastin is elastic. It helps alveoli to return to the normal shape after inhaling an exhaling Loss of elastin means I can’t recoil to as well. It was destruction of the alveoli wall which reduces the surface area of the alveoli so the rate of gas is exchanged decreases. The symptoms often include shortness of breathe and wheezing
What is the result of a reduction in gas exchange rate?
Less oxygen is able to diffuse into the bloodstream, the body cells receives less oxygen, and the rate of aerobic respiration is reduced. This means less energy is released, so the suffers often feel tired and weak.
Does correlation mean one thing causes another?
Not always
What should be the condition of your dissecting tools?
Clean, sharp and free from rust as blunt tools don’t cut as well and can be dangerous
In a lung dissection, how could you inflate the lungs?
Attach a piece of rubber tubing to the trachea and pump air into the lungs, using a foot or bicycle pump. Lungs will deflate by themselves because the last in the walls of the elastin in the walls of the alveoli
What is the trachea supported by?
C shaped rings of cartilage
How should you cut open the trachea in a lung dissection
Cartilage is tough you won’t open the trachea it’s best to cut it length way down the gap in the sea shaped rings use dissecting scissors or scalpels
How should you dissect a fish gill?
Place on a dissection tray,
gills are located on either side of a fish head, and they’re protected on each side by a bony flap called the operculum and supported by Gil arches
to remove the gillspush back to the operculum, use scissors to remove the gills . Cut each arch through the bone at the top and the bottom
How to carry out dissection on an insect
Fix insect dissecting board with pins to hold it in place,
Cut and remove a piece of exoskeleton from along the length of the insects abdomen. You can examine this trachea optical microscopes.
Ethical issues of dissecting animals
- morally wrong to kill animals just for dissections (however many dissections that are carried out in schools involve animals that have already been killed for meat)
- Concerns that animals used for dissection are not always raised in a humane way, (they may be subject to overcrowding, extremes or temps or lack of food or they may not be killed humanely)
- if animals are raised in school it’s important they are looked after properly and killed humanely to minimise suffering or distress
Features of the alveoli
- larger Sa to vol ratio
- movement of internal medium (eg, blood flow) maintain a diffusion gradient
- movement of environmental medium (air constantly moving in)
- very thin
-Partially permeable
Capillaries around the alveolu are ………, so what do red blood cells have to do
Thin
Squeeze through which increases the Sa of contact - they are also slowed so allows more time for diffusion
What % of oxygenated air is oxygen
21%
What % of oxygenated air is Co2
0.04%
What % of deoxygenated air is oxygen
16%
What % of deoxygenated air is co2
0.4%
What is digestion
The process by which larger molecules are hydrolysed by enzymes into small molecules which can be absorbed and assimulated
What does assimulated mean (digestion )
A part of the new composition
What does salivary amylase do
Hydrolysis alternate glycosidic bonds in starch to Disaccharide maltose in mouth
What maintains the PH in mouth and why
Minerals
For amylase optimum ( neutral)
why does no further breakdown happen in the stomach from amylase
Acidic conditions denature the amylase enzyme
Food in Small intestines - the remaining starch to maltose is broken down by what
pancreatic amylase hydrolase
What PH is the small intestines and how is it maintained
7-8
Bile
Maltose disaccharide is then hydrolysed into ……….. by ……….. in the ………..
Alpha glucose
Maltase
Ileum
How does maltase in the ileum work
Muscles in the intestine walls push food along ileum ( it’s epithelial lining produces the disaccharide maltose)
Is maltose secreted into the lumen of ileum
No
What is maltase a part of
The cell surface membrane of the epithelium cells of the ileum
What can maltase be described as
Maltase is membrane bound disaccharridase
Where is sucrase
Found in memebrane of the small intestines
Where is lactase found
Small intestine linning
What are proteins hydrolysed be
Peptidases
What do endopepridases hydrolyse
The peptide bond between amino acid in the centre of the molecule
What does exopeptidase hydrolyses
Terminal peptide bonds between amino acids at the end of each molecule , they release dipeptides and single amino acids
What does dipeptidase hydrolyse
The bond between 2 amino acids
Where are dipeptidase found
Part of the CSM of ilium epithelial cells
( they are membrane bound )
What hydrolysis lipids
Lipase
Where is lipase produced
Pancrease
What do lipase specifically hydrolyse to form what
Ester bonds found in triglycerides to form fatty acids and monoglycerides
What is a monoglyceride
Glycerol and 1 fatty acid
How does lipase work
fats and oils firstly split into tiny droplets called micelles by bile salts made in the liver (emulsification) this increases surface area so that the action of lipases is sped up
Why can’t large biological molecules cross cell membranes
And what does this mean
Too big
Can’t be absorbed form the gut into the blood
How can large molecules be broken down into smaller momlecukes
Hydrolysis reactions
What are hydrolysis reactions
Breaks bonds by adding water
Why are differnt enzymes needed to catalyse the breakdown of differnt food molecules
As enzymes only work with specific substrates
What is amylase
A digestive enzyme that catalyses the conversion of starch int the smaller sugar maltose
How does amylase digest starch
Hydrolysis of glycosidic bonds in starch
Where is amylase produced
Salivary glands
Pancrease (releases amylase Into small intestines)
What are membrane bound disaccharides and what do they do
Enzymes that are attached to the cell membrane of epithelial cells losing the ileum
Break down disaccharides into monosaccharides (involving hydrolysis of glycosidic bonds)
What enzyme breaks down maltose into what
Maltase
Glucose + glucose
What enzyme breaks down sucrose into what
Sucrase
Glucose + fructose
What enzyme breaks down lactose into what
Lactase
Glucose + galactose
How can monosaccharides be transported across the cell membrane of ileum epithelial cells via what
Transporter proteins
What does lipase catalyse the breakdown of into what
Lipids into monoglycerides and fatty acids
How does lipase work
Involves hydrolysis of ester bonds in lipids
