exchange surfaces Flashcards
(21 cards)
why do multicellular organisms require specialised gas exchange
~ diffusion inefficient
~ low sa:vol
~humans- maintain body temp
~fish + humans very active animals
features of an efficient gas exchange surface
~large sa:vol - root hair cells
~thin/ short distance- alveoli
~steep conc gradient maintained by ventilation or blood supply - gills
describe the trachea and its role within the mammalian gaseous exchange system
~wide tube supported by c-shaped Cartlidge to keep the air passage open during pressure changes
~lined with ciliated epithelium cells which move mucus, produced by goblet cells, towards the throat to be swallowed, preventing lung infections
~carries air to the bronchi
describe the bronchi and there function in the mammalian gaseous exchange system
~like the trachea they are supported by rings of cartilage and are lined by ciliated epithelium cells and goblet cells
~however they are narrower and there are two of them , one for each lung
~allow passage of air into the bronchioles
describe the bronchioles and their function in the mammalian gaseous exchange system
~narrower than the bronchi
~do not need to be kept open by Cartlidge, therefore mostly have only smooth muscle and elastic fibres so that they can contract and relax easily during ventilation
~ allow passage of air into the alveoli
describe the alveoli and their function in the mammalian gaseous exchange system
~mini air sacs, lined with epithelium cells
~site of gas exchange
~extensive capillary network to maintain conc gradient
~ walls covered in moisture
~one cell thick - short diffusion distance
explain the processes of inspiration and the changes that occur throughout the thorax
~external intercostal muscles contract ( while internal relax ), pulling the ribs up and out
~diaphragm contracts and flattens
~volume of the thorax increases
~air pressure outside the lungs is therefore higher than the air pressure inside , so air moves in to rebalance
explain the processes of expiration and the changes that occur throughout the thorax
~external intercostal muscles relax
~diaphragm relaxes and domes up
~volume of the thorax decreases
~air pressure inside the lungs is therefore higher than the air pressure outside, so air moves out to rebalance
~is a passive process
~elastic fibres in alveoli also recoil pushing are out
~ strong exhalation - internal intercostal muscles contract while external relax so is a antagonistic relationship- is an active process
explain how a spirometer works
~used to measure lung volume. a person breathes into an airtight chamber which leaves a trace on a graph which shows the volume of the breaths
define vital capacity
~ the maximum volume of air that can be expelled from the lungs in one breath. can be calculated from the spirometer graph by finding the maximum amplitude
define tidal volume
~the volume of air we breathe in and out during each breath at rest. can be calculated from the spirometer graph by finding the amplitude at rest
define breathing rate
~the number of breathes we take per minute. can be calculate from the spirometer graph by counting the number of peaks in one minute
what is the process known as by which oxyhaemoglobin releases its o2 to respiting cells
dissociation
with reference to protein structure, explain how increasing hydrogen ion levels affects haemoglobin
more hydrogen ions lower PH, tertiary structure of haemoglobin altered which reduces its affinity for oxygen
describe how the charge inside a RBC is maintained when hydreogencarbonate ions diffuse into the plamsa
chloride ions move into the RBCs from the plasma
what is the net result of the bohr effect
more oxygen is released where more carbon dioxide is produced in respiration
what is the main difference between foetal haemoglobin and adult haemoglobin
it has a higher affinity for oxygen than adult haemoglobin
describe the formation of hydrogen carbonate ions
carbon dioxide from the blood plasma diffuses into RBCs and combines with water to form carbonic acid ; carbonic acid then dissociates into hydrogen carbonate ions and protons
describe 3 ways in which carbon dioxide is transported
5% dissolved directly in the plasma
10% directly with haemoglobin in the form of carbaminohaemoglobin
85% in the form of hydrogen carbonate ions
describe how the PH inside a RBC is buffered as hydrogen ions build up inside, making the RBC very acidic
hydrogen ions are taken out of solution and combined with haemoglobin to form haemoglobinic acid HHB
describe the simple structure of haemoglobin
-4 subunits - each with a polypeptide chain and a haem group
-haem groups contain an FE2+ ; iron ions can attract and hold an oxygen molecule
