Exchange Surfaces Flashcards
What are the main factors needed for an exchange system
-size in single celled organisms substances can diffuse in and out directly so diffusion is quick
In multicellular organisms diffusion is too slow as the cells are too deep in the body
- small organisms have a large surface area to volume ratio so have a large surface to supply all their cells with oxygen
Large organisms have a small surface area to volume ratio so diffusion is not efficient
-multicellular organisms have a high metabolic rate than single celled organisms so they use up oxygen and nutrients faster
What is the surface area to volume ratio formula
Surface area / volume
What are features of a good exchange surface
Large surface area -more space for particles to move e.g root hair cell covered in microscopic hairs increasing rate of absorption
Thin - so short diffusion pathway e.g alveoli made from single layer of alveolar epithelium which helps to decrease distance
Good blood supply- maintains steep concentration gradient e.g fish gills so diffusion can occur rapidly
How does air pass through in a mammalian gas exchange system
Nose > trachea > bronchi > bronchioles > alveoli
Explain the advantages of large surface in relation to lungs
- many alveoli means large surface area
-molecules can pass through
-alveoli lined by moisture which evaporated when we breathe out
What is the benefit of thin barrier in relation to the lungs
-alveoli is one cell thick
-short diffusion pathway
-capillaries in close contact with alveoli so easy diffusion
-squamous cells are thin for diffusion
What is the benefit of good blood supply in lungs
-helps maintain good blood supply
-so diffusion can occur rapidly
-highe level of CO2 in blood than alveoli so it diffuses in alveoli blood is transported away from lungs to ensure conc of O2 in blood is kept lower than that in the alveoli so O2 diffuses in the blood
What is the benefit of ventilation in relation to lungs
Replaces used air with fresh air bringing in O2 and removing CO2
What are the mechanics of inspiration (inhalation)
-Diaphragm contracts
-external intercostal muscles contract pulling ribs up and out
-volume of chest increases
-pressure in chest decreases
-air moves into lungs
What are the mechanics of expiration (exhalation)
-diaphragm relaxes
-intercostal muscles contract pulling ribs down and in
-volume decreases in chest
-pressure increases in chest
-air moves out of lungs
What is the role of elastic fibres
Stretch during inhalation
Recoil during exhalation
What is the role of ciliated epithelium
-keeps lung healthy by moving mucus along
What is the role of goblet cells
-secretes mucus and traps dust and pathogens
What is the role of cartilage
-prevents lungs from collapsing
What is the role of smooth muscle
-contracts to control airflow
What 2 tissues found in the lungs and airways
-ciliated epithelial
-squamous epithelial
What is oxygen consumption measured with
Spirometer
How does using a spirometer work
-float chamber consisted of oxygen floating on a tank of water
-during inspiration air is drawn from the chamber so the lid moves down
-during expiration air returns to the chamber raising the lid
-movements are recorded to make a trace
What is the use of soda lime in this experiment
-co2 rich air is passed through a chamber of soda lime which absorbs the CO2 which allows measurement of O2 concentration
What are precautions needed for this experiment
-mouthpiece must be sterile
-soda lime must be fresh
-participant must be healthy
What is vital capacity and what does it depend on
The maximum volume of air that can be moved by lungs in one breath
Depends on:
-Size of person
-Age and gender
-level of regular excercise
What is tidal volume
Volume of air moved in and out with each breath
What is residual volume
Volume of air that remains in lungs after breathing out
What are adaptations of bony fish
-2 rows of filaments that are thin and fold into many lamellae
-this gives a large surface area
-capillaries carry deoxygenated blood close to the surface of the secondary lamellae where exchange takes place
-gives it a shorter diffusion pathway
What is the countercurrent flow
-blood flows along gill arch and filament to the secondary lamellae
-blood then flows in the opposite direction which crates a countercurrent flow
-this absorbs the maximum oxygen
Explain the ventilation in bony fish
-Buccal cavity lowers drawing water in
-mouth closes and floor is raised again
-this pushes water through the gills
-as water is pushes through the buccal cavity the operculum moves outwards
-this reduces pressure in opercular cavity helping water flow through the gills
How do you see the fish gills properly when doing a dissection
Cut the operculum out as it covers it
What type of circulatory system do insects have
Open
Circulation is slow and is affected by body movements
Explain the tracheal system in insects
Supplies air to all respiring tissues
Air enters a spiracle (pore)
Air is transported through a series of tubes (trachea)
These divide into tracheole which are open and have tracheal fluid
Gas exchange takes place between air in tracheole and the tracheal fluid
What happens to the tracheal fluid when the insect is active
Tracheal fluid can be withdrawn into bod fluid to increase surface area of the tracheole exposed to air
So there’s more O2 when insect is active
Explain how inspiration can be demonstrated with a balloon and jar
-sheet is diaphragm which is pulled down
-This increases volume in thorax
-Pressure decreases
-Atmospheric pressure is higher
-Air rushes in ballon (which is lungs)
