3.1 exchange surfaces Flashcards
(37 cards)
why can’t large organisms rely on simple diffusion
- have a lower volume to surface area ratio so there is less surface area for the absorption of nutrients and gases and secretion of waste products
why is having a high surface area to volume ratio good
- large surface area allows for maximum absorption of nutrients and gases and secretion of waste products
- small volume means the diffusion distance to all organelles is short
large organisms have a…
low sa:v ratio and so have developed a specialised transport system
why do organisms need a specialised gas exchange system
Supply of Oxygen
- Organisms require ATP in order to carry out the biochemical processes required for survival. The majority of ATP is produced through aerobic respiration which requires oxygen
Removal of Carbon Dioxide:
- Carbon dioxide is a toxic waste product of aerobic respiration
- If it accumulates in cells/tissues it alters the pH
what sis the metabolic rate
the amount of energy expended by that organism within a given period of time
what is basal metabolic rate (BMR)
the metabolic rate of an organism when at rest. The BMR is significantly lower than when an organism is actively moving
During periods of rest, the body of an organism only requires energy for the functioning of vital organs such as the lungs, heart and brain
how to calculate the matbolic rat eo fan organism
Oxygen consumption (respirometers)
Carbon dioxide production (carbon dioxide probe)
Heat production (calorimeter)
what doe sexchange surfaces have
- Large surface area
- Short diffusion distance (thin)
- Good blood supply
- Ventilation mechanism
how have root hair cells sepcialised for gas exhange
- larger surface area
- large vacuole containign sap to increase water potential graident
how are alveoli adapted for good gas exchange
- air in the alveoli contains a high concentration of oxygen. The oxygen diffuses from the alveoli and into the blood capillaries
- blood in the capillaries has a relatively low concentration of oxygen and a high concentration of carbon dioxide. The carbon dioxide diffuses from the blood and into the alveoli and is then exhaled
- walls of the alveoli are only one cell thick and these cells are flattened gases have a very short diffusion distance so gas exchange is quick and efficient
- Large number of alveoli - increases the surface area available for oxygen and carbon dioxide to diffuse across
- Extensive capillary network - constant flow of blood through the capillaries means that oxygenated blood is brought away from the alveoli and deoxygenated blood is brought to them, maintains the concentration gradient necessary for gas exchange to occur
describe the structure of gills
main gill arch with blood vessels, one to carry oxygenated and deoxygenated blood
going off the igll arch are fillaments which have lamellae on them
why do fish need a good blood supply
- helps to maintain a concentration gradient as it is continuously flowing, bringing substances that have just entered the blood away from the exchange site
- Fish gills are adapted to directly extract oxygen from water as they have a large capillary network
- extensive capillary system that covers the gills ensures that the blood flow is in the opposite direction to the flow of water - it is a counter-current system
- ensures the concentration gradient is maintained along the whole length of the capillary
- Water continues to supply the blood with oxygen along the whole gill arch and ends with water with the lowest oxygen concentration adjacent to the most deoxygenated blood with continued diffusion occurring
what is cartilage
- strong and flexible tissue found in various places around the body
- c-shaped rings - flexibility, They are C-shaped to prevent any friction from rubbing with the oesophagus located close behind
- hekp suport and prevents collapse whe the air pressur einside is low after expirateion
what si ciliated epithelium
- specialised tissue found along the trachea down to the bronchi
- Each cell has small projections of cilia which waft mucus, dust and bacteria upwards and away from the lungs to cough out or swallow
what is goblet cells
- found scattered throughout the ciliated epithelium in the trachea
- mucus-producing cells that secrete viscous mucus which traps dust, bacteria and other microorganisms and prevents them from reaching the lungs
- mucus is then swept along by the cilia of the ciliated epithelium upwards and is swallowed
- mucus and any microorganisms will then be destroyed by the acid in the stomach
what are squamous epithelium cells
forms the structure of the alveolar wall and so is very thin and permeable for the easy diffusion of gases
where is smooth muscle found in the circulatry system
- throughout the walls of the bronchi and bronchioles
- helps to regulate the flow of air into the lungs by dilating when more air is needed and constricting when less air is needed
where are elastic fibres found in the circulatry system
present in all lung tissues. They are very important as they enable the lung to stretch and recoil. This ability to recoil is what makes expiration a passive process
funcion of capilaries in gas exchange
Each alveolus is surrounded by an extensive network of capillaries
Carbon dioxide diffuses out of the capillaries and into the alveoli to be exhaled, while oxygen diffuses the other way from alveoli and into the capillaries to be carried around the body
These capillaries have a diameter of around 3-4µm, which is only wide enough for one red blood cell to travel through at any one time
This ensures that there is sufficient time and opportunity for gas exchange to occur
componenets of gas echange system
nasal cavity:
- hairs and mucus membrane, warms cleans and humidifies air
trachea:
- channel that allows air to travel to the lungs
- lined with ciliated epithelium and goblet cells to trap dust and bacteria to prevent them from entering the lungs
- wall of the trachea contains smooth muscle and elastic fibres
Bronchi:
- similar structure to the trachea but they have thinner walls and a smaller diameter
- artilage in the bronchi can form full rings, and irregular blocks
Bronchioles:
- narrow self-supporting tubes with thin walls, not ussualy suprted by cartilage but somemay have some cartilage
- large number of bronchioles
- lined with ciliated epithelium though usually do not contain any goblet cells
- vary in size and structure, getting smaller as they get closer to the alveoli - laregr have elastic fibres and smooth muscle
alveoli:
- located at the ends of the bronchioles
- single layer of epithelium
- extensive capillary network
- A watery fluid lines the alveoli, facilitating the diffusion of gases
pleural membranes:
- smooth surface, secrete pleural fluid, lubricant to allow lungs to move freely
intercostal muscles:
- 2 sets, internal and external, move ribcage up and out, and down and in
diaghram:
- sheet of muscle and fibrous tissue, contract, flatten increase volume of thorax, inhilation
describes what happens when you inhale
- contraction of diaghram so it flattens
- contraction of externla intercostal muscles so ribs move up and out
- internal intercostal muscles relax
- incrrease in volume of thorax
- decrease in presur ein thorax
- pressure gradient established from atmosphere to alveoli
inhalation - equalises pressure
describes what happens when you exhale
- relaxation of diaghram, dome shape
- relaxatio of external intercostal muscles
- contraction of internal intercostal muscles
- elastic fibres of alevoli and return to normal size
- decrease in volume of thorax
- increase in pressur ein thorax
- presur egradient established from alveoli to atmosphere
exhale - pressure equalises
what is a spirometer
- a device used to record the volume of air moving in and out of the lungs as we breathe
- person (subject) being examined breathes in and out through the spirometer
- Carbon dioxide is absorbed from the exhaled air by soda lime in order to stop the concentration of carbon dioxide in the re-breathed air from getting too high
- As the subject breathes through the spirometer, a trace is drawn on a rotating drum of paper or a graph is formed digitally, which can be viewed on a computer
- From this trace, the subject’s vital capacity, tidal volume and breathing rate can all be calculated
what is total lung capacity
The volume of air in the lungs at maximum inflation
