3.1 exchange surfaces Flashcards
why do we need specialised exchange systems
larger organisms there are multiple layers of cells so body surface no longer sufficient
diffusion cannot take place quick enough and supply enough of o2 and nutrients etc.
3 factors that affect the need for exchange systems
size
SA:V
activity level
why does size not matter for exchange in single celled organisms
cytoplasm is close enough to environment (short diffusion pathway) so diffusion can supply enough oxygen and nutrients
why is size an issue for exchange in multi-cellular organisms
there is several layers of cells and oxygen and nutrients have a larger diffusion pathway happens too slowly
describe the SA:V in small and large organisms
small = large SA:V
large = small SA:V
describe the impact of activity levels for the need for specialised exchange systems
lots of metabolic activity = uses energy = need a good supply of nutrients and oxygen
describe features of a good exchange system
good blood supply - maintain conc. gradient
large SA - provides more space for molecules to pass through
thin barrier - permeable, reduce diffusion distance
define breathing rate
number of breaths per minute
define oxygen uptake
volume of oxygen absorbed by lungs in one minute
define tidal volume
volume of air inhaled or exhaled per breath
define vital capacity
maximum volume of air exhaled after a maximum inhalation
what is a spirometer
device used to measure movement of air into and out of lungs
what is a float chamber spirometer
chamber of air floating on a tank of water
what happens to a float chamber spirometer during inspiration and expiration
air drawn out of chamber
lid moves down
air returns to chamber
raises lid
movement recorded by datalogger to produce a trace
describe the purpose of soda lime
absorbs CO2 as its exhaled to allow measurement of oxygen uptake
precautions taken when using spirometers
healthy subject
fresh/functioning soda lime
no air leaks
sterilised mouthpiece
water chamber overfilled
how do you record oxygen uptake by spirometer
breathing in
oxygen absorbed by blood
replaced by CO2
CO2 now absorbed by soda lime
volume of air decreases in chamber
and volume of CO2 released and absorbed by sodalime = volume of oxygen absorbed by blood
calculating vital capacity
Tidal vol. + inspiratory reserve vol. + expiratory reserve vol.
calculating minute ventilation
Breathing rate x tidal volume
calculate total lung volume
Vital capacity + residual volume
the passage of air you breathe in
Nose - Trachea - bronchi - bronchioles - alveoli
What happens during gas exchange in mammals
Oxygen diffuses from air in alveoli into bloodstream
Carbon dioxide diffuses from blood to air in alveoli
How do lungs maintain a concentration gradient
Large SA
Permeable Barrier
Thin barrier - one cell thick, reduce diffusion distance, squamous cells
good blood network
define ventilation
Action of intercostal muscles and diaphragm allowing inhaling air and expiring CO2
What does ventilation ensure
Concentration of O2 in air of alveoli is higher then in the blood
Concentration of CO2 in the alveoli is lower then the blood
To maintain a concentration gradient
What happens during inspiration
Diaphragm contracts (moves down/ flattens)
External intercostal muscles contract (raises ribs)
Volume of chest cavity increases
Pressure decreases
Air moves in
What happens during expiration
Diaphragm relaxes (pushes up)
External internal muscles relax (ribs fall)
Volume of chest cavity decreases
Pressure in lungs increase
Air moves out
How do bony fish exchange gases
Exchanges gases with the water they live in
Use gills to absorb dissolved O2 and release CO2
What is the operculum
Bony flap that covers and protects gills
What are filaments/ primary lamallae
Slender branches of tissue which makes up gills, attached to bony arc
What are secondary lamallae/ gill plates
Folds of filaments to increase SA
what is the role of lamallae/ filaments in fish
to increase the surface area
define countercurrent flow
Two fluids flow in opposite directions
How does countercurrent flow work in gills
Blood in gills flow in opposite direction to slow of water to maintain concentration gradient
What is the buccal cavity
Mouth of bony fish
How do bony fish keep water flowing over gills
Buccal - opercular pump
How does water get drawn into and out of a fish
Floor of mouth moves down - pressure decreases- water moves in
Floor closes - pressure increases - pushes water through gills
How is water pushed out though the gills
Buccal cavity closes - water pushed out of buccal cavity - operculum moves outwards - reduces pressure in operculum cavity - water flows out
What is an insects circulatory system like
An open circulatory system in which body fluids are both body and tissue fluid
What is the tracheal system
System of air filled tubes in insects
define spiracle
Opening or pore that allows air in or out of the trachea
define trachea
Series of tubes that transport air
define tracheoles
Trachea dividing into smaller branches
define tracheal fluid
Fluid found at the end of the tracheoles
Where does gas exchange occur in insects
Between air in tracheoles and fluid in tracheole fluid
What happens in active tissues in insects
Tracheal fluid is withdrawn to increase the surface area of the trachea wall exposed to air
How does ventilation occur in insects
Happens by movements of the body
How does the tracheal system allow ventilation
Tracheal wall is flexible and the system expands
Acts as air sacs gets squeezed by muscles
Repetitive expansion and contraction of sacs ventilate the system
How does wing movement of insects cause ventilation
Wings alter volume of thorax
Volume decrease - pressure increases in system - air pushed out
Volume increases - pressure drops - air pushed back into tracheal system
How does the abdomen in insects affect ventilation
Volume altered - expands - front spiracles open - air enters system
What cells make up lung tissue
Squamous cells and elastic fibres
What are squamous cells
flattened epithelial cells in the alveoli
What are ciliated epithelium
Lines airways
Hairlike extensions
Helps to waft mucus up trachea
What are goblet cells
Cells that secrete mucus
Traps pathogens
describe cartilage
Form of connective tissue
Prevents airways collapsing
C shaped to allow flexibility
Describe smooth muscles
Involuntary muscles
Contract without conscious thought
how are airways constricted
smooth muscle will contract and constrict the airway - makes the lumen narrower - restricts air flow
why would airways need to be restricted
harmful substances in air
allergic reaction etc.
how do smooth muscles and elastic fibres work together
smooth muscle contracts- deforms elastic fibres
muscles relax- elastic fibres return to normal shape
