Surface area and gas exchange (p1) Flashcards
paper 1 (and 3)
surface area
total area of an organism that is exposed to the external environment
volume
total internal volume (amount of space inside an organism)
as the surface area _______ the surface area:volume ratio decrease.
This is because volume ________ more rapidly than the surface area as the size increases.
as the surface area increases the surface area:volume ratio decrease.
This is because volume increases more rapidly than the surface area as the size increases.
single cell organisms have a ____ SA:V ratio which allows for exchange of substance via simple __________. large surface area allows for maximum absorption of nutrients and secretion of gases. small ______means diffusion distance to all organelles is short.
single cell organisms have a high SA:V ratio which allows for exchange of substance via simple diffusion. large surface area allows for maximum absorption of nutrients and secretion of gases. small volume means diffusion distance to all organelles is short.
in ____ organism diffusion across the outer membrane is too slow because:
1.________ diffusion distance to cells and tissues in the organisms.
2.less ______ for absorption and secretion of substances.
in multicellular organism diffusion across the outer membrane is too slow because:
1.longer diffusion distance to cells and tissues in the organisms.
2.less surface area for absorption and secretion of substances.
As an organism increase in size the SA:V ratio _______
As an organism increase in size the SA:V ratio decreases
large___________ animals and plants evolved __________ to facilitate exchange of substances with environment. Have a large variety of specialised,cells, tissues,organs and systems.
large multicellular animals and plants evolved adaptations to facilitate exchange of substances with environment. Have a large variety of specialised,cells, tissues,organs and systems.
rather than diffusion multicellualr organism use specialised exchange ________ to absorb and excrete substances.
rather than diffusion multicellualr organism use specialised exchange organs to absorb and excrete substances.
exchange organ example
lungs
mass transport
multicellular organisms need efficent systems to carry substances to and from indivdual cells e.g circulatory system.
need for a specialised system for gas exchange
- supply of oxygen-organisms require ATP for survival. Majority of ATP produced through aerobic respiration requring oxygen
- removal of co2-is a waste product of aerobic respiration, if accumulates in tissues alters the pH.
Gas exchange surface
gas exchange occurs over gas exchnage surface= a boundary between outside envrionment and internal environment. organisms need oxygen and co2 to diffuse across exchange surface as quick as possible.
what do gas exchange surfaces have in common
-large surface area
-thin= short diffusion pathway across surface
-maintains a steep concentration gradients. (increases rate of diffusion)
relationship between surface area to volume ratio and metabolic rate.
-the greater the mass of an organism, the higher the metabolic rate
-although metabolic rate increases with body mass the BMR per unit of body mass is higher in smaller animals than in larger animals
-Smaller animals have a greater SA:V ratio so they lose more heat, meaning they have to use up more energy to maintain their body temperature
metabolic rate
energy expended by an organism within a given time
basal metabolic rate (BMR)
metabolic rate when organism is at rest. BMR is significantly lower than when organism is moving
how can metabolic rate be measured
oxygen consumption, co2 production, heat production
body ______ and shape affects heat exchange as impacts surface area to volume ______.
body size and shape affects heat exchange as impacts surface area to volume ratio.
Other behavioural and physiological adaptations other than size and shape animals may have
1- animals with high SA:V ratio tend to lose more water . some small desert animals hvae kidney structure adaptions to produce less urine tocompensate
2- to support high BMR small mammals in cold regions eat large amounts of high energy foods e.g seeds and nuts
3-larger organisms in hot regions e.g elphants and hippos fid it hard to keep cool due to relatively slow heat loss . Elphants hace large flat ears increas SA. hippos spend much of the day in water-bhevaioural adaptaion.
Fish use a _______–_______ system for exchange
Fish use a counter current system for exchange
There is a _______ concentration of oxygen in water than air. so fish have special _______ to get enough of it.
There is a lower concentration of oxygen in water than air. so fish have special adaptaions to get enough of it.
structure of the gills
each gill is made out of thin plates called gill filaments, which give big surface area for of exchange gases
gill filaments are covered in lots of lamellae increasing surface area further.
lamellae have lots of blood cappilaries and thin surface layer to speed up diffusion
counter current system in fish gills
1.blood flows though the lamellae in one direction water flows over in the opposite direction
2. this is called a coungter current system
3.maintains the concerntartion gradient between the water and the blood
4.concentraions of oxygen in water always higher than in blood,so as much oxygen as possible diffuses from the water to the blood.
water containing _____ enters the fish through the mouth and passes out through the _______.
water containing oxygen enters the fish through the mouth and passes out through the gills
how does the counter -current system maintain a concentration gradient
-water and blood flow opposite directions
-so water with relatively high oxygen always flows next to blood with lower concerntartion
Adaptations of gas exchange surfaces, shown by gas exchange:
-across the body surface of a _______-celled organism
-in the _______ system of an insect (tracheae, tracheoles and spiracles)
-across the gills of fish (gill lamellae and filaments including the counter-______ principle)
-by the _______ of dicotyledonous plants (mesophyll and stomata).
Adaptations of gas exchange surfaces, shown by gas exchange:
-across the body surface of a single-celled organism
-in the tracheal system of an insect (tracheae, tracheoles and spiracles)
-across the gills of fish (gill lamellae and filaments including the counter-current principle)
-by the leaves of dicotyledonous plants (mesophyll and stomata).
Gas exchange in insects
-terrestrial insects have microscopic airfilled pipes that they used for gas exchange called tracheae
-air moves into the tracheae through pores on the surface called spiracles.
-oxygen travels down concentration gradient towards the cells
-tracheae branch off smaller tracheoles which have thin permeable walls and go to individual cells, means oxygen diffuses directly to the respiraing cells (the insects circulatory system doesn’t transport o2)
-CO2 moves down concerntration gradients towards the spiracles , where it is released into the atmosphere
-use rhythmic abdominal movements to move air in and out if the spiracles.
how do insects control water loss
-if loosing to much water close spiracles using muscles to prevent all water loss.
-have a water proof waxy cuticle over there bodies (exoskeleton) and tiny hairs around their spiraces which reduces water loss.
- small surface area: volume ratio minismise area from which water is lost.
what ways is the tracheal system in insects designed to allow gas exchange
-larger surface area of tracheoles and tracheae.
-short diffusion pathway from spirical to tracheae to tracheoles.
-concertrantion gradient between CO2 and oxygen allowing diffusion
why are the end of the tracheoles filled with fluid ( insects)
-tracheal system contains a special fluid for carrying oxygen
-sometimes water build up in the bottom of the tracheoles causing slow diffusion
-to removes this lactic acid begins to build up (anaerobic repiration) this decreses the water potential , water then moves back into the cells. (osmosis)
Spiracles (insects)
Tiny holes that let the air enter the body and prevent water loss. controlled by specialised muscles to be opened and closed. (are mostly closed to prevent water loss)
used to pass air into the trachea
trachea (insects)
Tube lined with chitin , branches into smaller tubes called tracheoles (contribute to large surface area)
tracheoles (insects)
deliver oxygen to cells and tissues of the insect
lined with a single layer of cells to reduce diffusion distance
fluid filled ends
chitin (insects)
inpermeable rings work to stop structure collapsing . Impermeable stop diffusion
lactic acid- oxygen dissolved into this fluid when reaches indvidual cells through simple diffusion, ______is released from this proccess into the environment through the _________
(insects)
lactic acid- oxygen dissolved into this fluid when reaches indvidual cells through simple diffusion, CO2 is released from this proccess into the environment through the spiracles
exoskeleton (insects)
all insects have an exoskeleton, with a waxy coating that is impermeable to gases
how does gas exchange occur at respiring tissues ( insect)
-concentration gradient created as oxygen used by respiring tissues allowing o2 to diffuse through spiracles via diffusion (co2 produce by respiring tissues moves out)
how does gas exchange occur at respiring tissues in very active flying insects
-active flying insects require more rapid intake of oxygen. so create a mass flow of air into the tracheal system by
-closing the spiracles,using muscles to create a pumping movement for ventelation
-during fligh the production of lactate in respiring tissues decreas water potentila of muscle cells
-water in narrow end of tracheoles drawn into respiring cells by osmosis
-this allows gases to diffuse more quickly
limitations of insect tracheal system
relies on a short diffusion pathway so they are limited to how big they can become
Gas exchange in dicotyledonous plants
-need carbon dioxide for photosynthesis,produce oxygen as a waste product
-they need oxygen for respiration,which produces carbon dioxide as a waste product
Structural and _________ compromises between the opposing
needs for efficient gas exchange and the limitation loss
shown by terrestrial _________and xerophytic plants
Structural and functional compromises between the opposing
needs for efficient gas exchange and the limitation of water loss
shown by terrestrial insects and xerophytic plants
the main gas exchange surface is the surface of ______ cells in the leaf.
they are well adapted-they have a large surface area
Gases move in and out through special pores in the _______(mainly lower) called _______. They can open for gas exchange and close if loosing to much water._______ cells control the opening and closing of the stomata.
the main gas exchange surface is the surface of mesophyll cells in the leaf.
they are well adapted-they have a large surface area
Gases move in and out through special pores in the epidermis (mainly lower) called stomata. They can open for gas exchange and close if loosing to much water. Guard cells control the opening and closing of the stomata.
upper epidermis
layer of tightly packed cells
waxy cuticle
waterproof
paliside mesophyll
layer of elongated cells with chloroplasts
spongy mesophyll
-has an extensive network of air spaces
-air spaces in spongy mesophyll layer to diffuse rapidly into cells
lower epidermis
layer of tightly packed cells
Guard cells
control opening and closing of the stomata
stomata
-tiny pores usually on the underside of leaves
-usually kept open during the day to allow gas exchange
-each is surroinded by guard cells which open and close the stomatal pore
-in this way control rate of gas exchange and water loss by evapouration-as stomata are closed at time water loss would be excessive
mechanism of gas exchange in plants
-when guard cells are turgid (full of water) stomata remains open allow air to enter the leaf.
-air spaces in spongy mesophyll layer to diffuse rapidly into cells
-CO2 is used up quickly in photosynthesis by cells containing chloroplast -maintaing the concerntration gradient
-there is no active vetinlation required as thinnes of plant tissues and presence of stomata create a short diffusion pathway
how do guard cells control stomata open and close
-when guard cells are turgid (full of water) stomata remains open allow air to enter the leaf.
-if plant become dehydrated the guard cells become flaccid and stomata shut
some plants are specially adapted to warm,dry and windy habitats where water loss is a problem. these plants=xerophytes. Some adaptaions are:
-stomata sunk in pits to trap water vapour, reducing the concerntartion gradient of water between leaf and the air . reducing evapouration.
-layer of hairs on the epidermis to trap water vapour around the stoma
-curled leaves with stomata on the inside protecting them from wind (wind can increase evapouration)
-reduced number of stomata so their are fewer places water can escape
-thicker waxy waterproof cuticles on leaves and stem to reduce evaporation.
why do humans need gas exchange?
-humans need to get oxygen into the blood for respiration
-they need to remove carbon dioxide produce by respiring cells
Ventilation and the exchange of gases in the lungs. The
mechanism of breathing to include the role of the diaphragm and
the _______ interaction between the external and internal _________ muscles in bringing about pressure changes in the
thoracic cavity.
Ventilation and the exchange of gases in the lungs. The
mechanism of breathing to include the role of the diaphragm and
the antagonistic interaction between the external and internal
intercostal muscles in bringing about pressure changes in the
thoracic cavity.
structure of the human gas exchange system
As you breathe in air enters the trachea. the trachea splits into two bronchi-one bronchus leading to each lung. Each bronchus branches off into smaller tubes called bronchioles. each bronchioles ends in small air sacs called alveoli. This where gas exchanged. the rib cage,intercostal muscles and diaphragm work together to move air in and out.
what allows gas exchange in humans?
breathing /ventilation
trachea (human)
aiway that leads from the mouth and nose to bronchi.
is lined with mucus secreting goblet cells and cilia .
the cilia sweep microorganisms and dust away from the lungs
lungs
humans have two,both a centeral part of the respiratory system and is where gas exchange takes place
bronchi
plural is bronchus . left and right bronchi are at the bottom of the trachea and are similar in structure but narrower.they lead to bronchioles
bronchioles
narrow tubes (less than 1mm) carry air from bronchi to alveoli.as they are so narrow and they have no supporting cartillage they can collapse
alveoli
main sight of gas exchange in the lungs.Tiny sacs with many structural adaptations to enable efficient gas exchange such as thin walls and a large sa:v ratio.
capillary network (humans gas exchange)
extensive network of capillaries surronds the alevoli and are an exchange surface between lungs and blood. during gas exchange oxugen diffuses from the alveoli into the capillaries while co2 diffuses the other way and is exhaled.
intercostal muscles
lie between ribs
internal contract leading to expiration
external contact leading to exhalation
ventilation (humans)
consists of inhalation and exhalation, controlled by movement of diaphragm, internal and external intercostal muscles and the ribs.
passage of air in humans
nose/mouth—> trachea——> bronchi—–> bronchioles—–> alveoli.
inspiration
-external intercostal muscles contract causing ribcage to move up and out
-diaphragm contracts cuasing it to flatten
-this increases the volume of the thoracic cavity, causing the pressure inside to decrease below atmospheric pressure.
-causing air to flow into the lungs
-is an active process (requires energy)
expiration at rest
-external intercostal muscles relax cuasing ribs to move down and back
-diaphragm contracts moving up into dome shape.
-this decreases the volume of the thoracic cavity increasing the pressure forcing air out of the lungs.
-passive
expiration forced/exercising
-active process
-during forced expiration external intercostal muscles relax internal contract pulling ribcage further down and in
-during this time the movement of the 2 sets of intercostal muscles is antagonistic
-abdominal muscles contact and push organs up against diaphragm increasing internal pressure forcing exhalation.
alveoli structure
wall of each alveolus is one cell think, this is the alveloli eputhelium ( short diffusion pathway)
walls of cappillaires are made from capillary endothelium (also 1 cell thick)
walls of alevoli contain elastin , which is elastic and helps alveoli return (recoil) to their normal shape after inhaling or exhaling air
has a layer of moisture
The essential features of the alveolar _________ as a surface over
which gas exchange takes place.
The essential features of the alveolar epithelium as a surface over
which gas exchange takes place.
movement of O2 and CO2 in human gas exchange system
-air contianing oxugen enters through nose/mouth and move down the trachea,bronchi and brinchioles into the alveoli.
-this movemnt is down the pressure gradient
-oxygen then diffuses (down the gradient) into the blood where it can then be transported around the body
-CO2 moves along it pressure and concerntration gradient but in the opposite direction to o2 so it can be breathed out.
Gas exchange in alveoli
oxygen diffuses out of the alveoli through the alveoli epithelium and capillary endothelium into heamoglobin in the blood. co2 diffuses into the alveoli from the blood
Factors affecting rate of diffusion human gas exchnage
alevoli have feature that allow quick gas exchange
thin excange surface-alveolar epithelium is only 1 cell thick providing a shirt diffusion pathway
large surface area-millions of alveoli so large surface area for gas exchnage
also a steep concerntration gradient of o2 and co2 between alveoli and capillaries increasing rate of diffusion this gradient is maintained by flow ofv blood and ventilation.
how is concerntartion gradient maintained human gas exchange
-exchange of oxygen and carbon dioxide occurs between alveoli and capillaires
- they are exchnaged ina process of diffusion
-air in the alveoli contains a high concerntration of o2 and the oxygen diffuses from the alveoli into the blood capillaries before being carried away to the rest of the body for aerobic respiration.
-bloof in the capillaries has a relatively low oxygen concerntration and high co2 concerntartion . co2 diffusies from the blood into the alveoli to be exhaled
breathing rate (ventilation)
number of breaths / minute
forced expiatory volume (FEV)
max volume of air that can be breathed out in a second
forced vital capacity
maxiumum volume of air it is possible to breathe forcefully out the lungs after a deep breathe in
tidal volume
volume of inspried air per breath at rest
total lung capacity
total amount of air the lungs can hold
lung diseases affect ________ and gas exchange
lung diseases affect ventilation and gas exchange
Tuberculosis
-pulmonary tuberculosis (TB) is cause by bacteria
-immune system cells build a wall around the bacteria forming small hard lumps called tubercles
-infected tissue in the tubercles dies and gas exchange surface is damaged reducing tidal volume
-reduced tidal volume=less air inhaled with each breath so have to breathe faster to take in enough oxygen
-common symptoms=persistant cough,coughing up blood and muscus,shortness of breathe,chest pains and fatigue
fibrosis
-scar tissue build up in lungs, may be due toinfection or exposure to substances such as asbestos or dust
-scar tissue=thicker and less elastic than normal lung tissue
-this means lungs ability to expand reduced meaning volume of air can hold reduced-reduce tidal volume and forced vital cpacity
-rate of gas exchange reduced as diffusion is slower acroos thick scarred membrane
-sympatoms faster ventilation to get enough oxygen, short breath,dry cough ,chest pain,fatigue and weakness
asthma
-aiways become inflamed and irritated usually becausex of allergic reactions to substances like dust or pollen
-during asthma attach smooth muscle of the bronchioles contracts and a large amount of mucus is produced, causing constriction on the airways making it diffucult to breathe
-airflow in and out of lungs reduced so less oxygen enters alveoli and moves into the blood, FEV severly reduced
symtoms wheezing tight test and shortness of breath in an attack symptoms can come on suddenly. can be relived by drugs often inhalers which cuase the muscles in the bronchioles to relax and open up the airways
emphysema
-cuased by smoking or long term exposure to air pollution- foriegn particles becoem trapped in alveoli
-cause inflammation attracting phagocytes to the area thye release the enzyme that breaks down the elastin in wall of alveoli
-alveoli can’t recoil to exhale air aswell so some air is trapped in alveoli
-can cause destruction to alveoli walls decreasing surface area reducing the rate of gas exchnage
-symptoms=shortness of breathe ,wheezing , increaed venitlation rate as they try and increase oxygen reaching hteir lungs
lung cancer
-tumours devlop if mutations occur in oncogenes or tumour-suppressor genes of bronchiol epitheliol cells-causing uncontolled mitosis and a mass of cells in lumen of the airways
-tomour becomes larger as has no methos of prgrammed cell death as it become larger it develops a blood supply (vascularisation)
-tumour interfers with normal working of lungs e.g squeezing against blood velssels or cancer cells enetr lymphatic system which may develop an second tomour
-symptoms,coughing up blood,persistant cough,coughing increased amount of muscus,bacl or shoulder pain ,wheezing,breathing difficulties,sudden wl.
COPD (chronic obstructive pulmonary disease)
- range of lung based diseases such as chronic bronchitis or emphysema
-cuased by goblet cells in ciliated epithelium becoming enlarged producing more mucus , this destorys cilia in trachea and prevents them from sweeping mucus away from lungs
-mucus contains bacteria,dust and other microorganisms and block narrow bronchioles,causing coughing,scar tissue and infection.
-infection attrats phagocytes to the lungs relasing elastase which damaged elasticity of alveolar walls
-without enough elastin alveoli breakdown na may burst creating large air spaces in alveoli (reduced SA)and patients become wheezing and breathless as the diseas progresses may need a constanr supply of o2.
symptoms shortness of breath, chronic/persistant cough,chest tighness,diffuculty breathing when excersisng or any physical activity.
why would a person with lung disease feel tired and weak
-reduce the rate of gas exchnage
-less oxygen diffuses into the blood, so body cells recive less oxugen and rate of aeribic respiration decreases
-less energy is released causing them to feel tired and weak.
risk factors of lung disease
smoking
air pollution
gentic makeup
infection
occupation
