Adaptions for Gas exchange Flashcards
What happens when a cell increases in size?
The diffusion pathway gets longer and so diffusion from outer the cell surface to the centre of the cell is slower
what happens when a cell becomes very large?
diffusion will not meet the cells needs
Why do cells need diffusion?
-to supply nutrients
-To remove waste
What are are examples of nutrients a cell needs?
Oxygen and glucose
what are examples of waste that must be removed via diffusion?
-carbon dioxide
-Urea from the liver cells
What is gas exchange?
process by which oxygen reaches cells and carbon dioxide is removed from them
What is ventilation?
-process of moving the respiratory medium over the respiratory surface to maintain a concentration gradient
what are respiratory mediums?
Air or Water
What is respiration?
Series of chemical reactions that results in the release of energy in the form of ATP
what must happen for an organism to become larger?
A number of cells must come together (it becomes multicellular)
which organism has the largest surface area:ratio volume?
Amoeba
what happens as the size of an animal increases?
The surface area to ratio volume decreases
what does unicellular mean?
Single celled
what is an example of a unicellular organism?
Amoeba
what type of cell is amoeba?
Aquatic
what are the features of a unicellular organ?
-Extremely large surface: volume ratio
-Diffusion is sufficient to the oxygen requirements of the organism
-Specialised gas exchange organs are not required
-Permeable membrane allows diffusion of gases
Gas exchange occurs across the whole surf
What is the size of amoeba?
100 µm
what are examples of simple multicellular organisms?
-Flatworm
-Earthworm
What type of simple multicellular organism is a flatworm?
aquatic
Why is there no specialised gas exchange organs in a flatworm? (simple multicellular organism)
-have evolved a flattened shaped overcome the problem of an increase in size- increases their SA:V, so cell no in the body is far from the surface (short diffusion pathway)
how do flatworms exchange gases? (simple multicellular organism)
-Exchange gases directly with environment via diffusion; diffusion across the permeable membrane is sufficient to meet the oxygen requirements of the organism
what type of simple multicellular organism is an earthworm?
Terrestrial
What shape has an earthworm developed and what is it restricted to?
Developed a tubular shaped and restricted to damp environments
why do earthworms secrete mucus?
To keep the cells of the body surface moist (allows gases to dissolve in diffuse)
What does the elongated shape of an earthworm provide?
provide the large surface area to volume ratio, compared with a compact organism (e.g. spherical shape) volume
How do earthworms exchange gases?
-The exchange gases directly with the environment by diffusion across the moist surface
What do blood vessels being close to the body surface in earthworm mean?
gases can diffuse in/out the blood, and then across the cells covering the body surface
What does blood circulating in the vessels of an earthworm do?
This maintains the concentration gradient for diffusion of oxygen into the cells and carbon dioxide out
what does the blood of an earthworm contain?
The respiratory pigment haemoglobin to carry oxygen to the body cells
What does an amoeba not contain?
blood or blood vessels because it’s a cell
why do multicellular organisms require specialised gas exchange surface?
-As size of organism increases, SA:V ratio decreases
-Diffusion across body=insufficient to provide enough O2 for organism to survive
-Larger organisms- more metabolically active- higher O2 demand so larger multicellular organisms need a specialised gas exchange surface between organisms and its external environment
-Provide a large no. of gas exchange surfaces to increase SA for diffusion
-Also need a method of circulation to distribute the gases around the body
-many animals have a toughened body surface so have internal gas exchange surfaces e.g. lungs
why have many animals and plants evolved exchange surfaces?
so that diffusion of gases into an out of cells can take place rapidly and efficiently
examples of gas exchange surfaces
-Gill lamellae in fish
-Alveoli in the lungs of mammal
-End of tracheoles of insects
what must all respiratory surfaces be in order to achieve the maximum rate of diffusion?
-Thin (shorter diffusion pathway)
-Moist (gases dissolve and diffuse)
-Large SA- relatively greater area for diffusion of gases
-Permeable to gases
what additional feature increases the efficiency of gas exchange and organisms which possess a circulatory system?
-extensive blood supply and blood circulates to maintain a diffusion gradient
why do insects need a good supply of oxygen for respiration?
Insects fly, which requires a lot of energy
Why is the gas chain system different from other land animals in an insect?
Because they do not use blood to transport gases
where does air diffuse into an insect?
Through paired holes called spiracles running along each side of the body (segments of the thorax and abdomen)
what do the spiracles in an insect lead to?
-System of branched Chitin lined air tubes called tracheae
why is it important that spiracles can open and close like valves?
-they open to allow gas to enter and close to reduce water loss.
what happens to an insect at rest?
simple diffusion of gases meets oxygen demands of the insect
what happens to an insect during periods of activity? (flight)
-Movements of the abdomen ventilate the tracheae
Why do insects have air sacs off the tracheae?
To aid ventilation of the tracheal system
What problems are caused by living in water? (fish)
-water contains less oxygen than air
-Rate of diffusion is slow water
-Water is a dense medium, so doesn’t flow as freely as air
How are fish categorised into two main groups?
according to the material which makes up their skeleton and also their gill ventilation mechanisms
What are the two types of fish?
-Cartilaginous fish
-Bony fish
what is an example of cartilaginous fish?
shark
What is an example of a bony fish?
Herring
what are the features of a cartilaginous fish? (shark)
-skeleton made entirely of cartilage
-Nearly all live in seawater
-Just behind head on each side are 5 gill clefts, which open at gill slits
-Water is taken into the mouth and forced through the gill slits when the floor of the mouth is raised
what is gas exchange like in a cartilaginous fish?
-Gas exchange involves parallel flow (blood in the capillaries circulates in the same direction as water flowing over the gills)
what are the features of a bony fish (herring)?
-Having an internal skeleton made of bone
-Gills are covered with a flap called the operculum
what does gas exchange in a bony fish involve?
-Counter current flow (blood in the gill capillaries circulates in the opposite direction as water flowing over the gills
What are the features of the head of a bony fish?
-four gills on each side (revealed when the operculum is pulled back)
-gill arch
-eye
-nostril
-mouth (buccal cavity)
what does the horizontal section through the pharynx and gill region of a bony fish show?
-water taken through mouth, passes over girls and expelled via the operculum
-Movement of buccal cavity floor and operculum allow a one-way current of water to flow through the girls for gas exchange
What is the ventilation mechanism in fish (water flows in)?
-The mouth opens
-The operculum closes
-The floor of the mouth (buccal cavity) is lowered
-Volume inside the mouth cavity increases
-The pressure inside the cavity decreases
-Water flows in as the external pressure is higher than inside the mouth.
what is the ventilation mechanism in fish (water flows out)?
The mouth closes
The operculum opens
The floor of the mouth (buccal) cavity is raised
Volume inside the mouth cavity decreases
The pressure inside the cavity increases
Water is forced out across the gill filaments as the external pressure is lower than inside the mouth.
what is the direction of water flow in ventilation when water flows in?
Higher
what is the direction of water flow in ventilation when water flows out?
lower
what are found along each gill of a bony fish?
-thin filaments and on these are gill lamellae (gill plates)
-Gill filaments therefore have a large surface area of a gas exchange
What do long gill filaments provide?
A very large surface area
what are found on each gill filament and what are they rich in?
-gill lamellae (plates) which are rich in blood capillaries
what does blood circulating through the gill lamellae create and what process occurs?
A concentration gradient- oxygen diffuses through the gill lamellae into the capillaries and carbon dioxide diffuses into the water
What is countercurrent flow?
water flows between the gill lamellae in the opposite direction to the blood flow
what is seen in the countercurrent flow diagram?
-Deoxygenated blood from the cells
-extensive capillary network in hill lamellae containing haemoglobin= efficient gas exchange
-oxygenated blood returns to body cells
-Water flows in the opposite direction to the blood flow
what is countercurrent flow like compared to parallel flow?
-blood always meets water with higher O2 conc
-Gradient for diffusion of oxygen into the blood from the water is maintained over the whole length of the gill
-Oxygen diffuses into blood across length of gill lamellae
-more efficient than parallel flow as it result in a higher blood oxygen saturation level
what is parallel flow like compared to countercurrent flow?
-water taken into mouth and blood flows through the gill capillaries in the same direction as water
-gas exchange very efficient at first as there is a very steep concentration gradient
-However, about halfway along the hill lamellae , equilibrium is reached and diffusion of oxygen and carbon dioxide is no longer possible
What are the five classes that vertebrates include?
-amphibians
-Reptiles
-Birds
-Fish
-Mammals
How was life to have thought to have evolved?
Life is thought to have evolved in water with animals adapting in order to colonise the land.
what does terrestrial mean?
Land living
what do amphibians include?
-Frogs
-Toads
-Newts
Where do amphibian larvae live and what do they have for gas exchange?
-Live in water and have gills for gas exchange
Why do adult amphibians live on land?
they are terrestrial
what gas exchange surfaces do adult amphibians have?
-one lung
-external gills
How does gas exchange occur in adult amphibians when inactive (at rest)?
-diffusion across the moist surface (skin)
how does gas exchange occur in amphibians when active (e.g. mating)
Using simple lungs and through the skin
what is the lung structure of an amphibian in comparison to a mammal?
-simple structure, with little infolding of the gas exchange tissues (small SA)
What are the structures of the human breathing system diagram?
-epiglottis
-larynx
-Rings of cartilage
-Trachea
-lung
-Bronchus
-heart
-Diaphragm
-Alveoli
-Plural membrane
-Rib
-Pleural cavity
-Internal intercostal muscle
-External intercostal muscle
-Bronchiole
what do the rings of cartilage support?
-The trachea
-The bronchi
-The bronchioles
what is the reason for the rings of cartilage?
-to prevent them collapsing when the pressure is lowering inspiration
What is the name of the airtight compartment of the body that encloses the lungs?
-Thorax
what are the features of a microscopic a transverse section of trachea (low magnification)?
-Cartilage
-ciliated epithelium containing goblet cells
What do goblet cells do?
Produce and secrete mucus to trap microorganisms
what do cilia do after goblet cells produce and secrete mucus to trap microorganisms?
-waft to move the mucus up and out of the trachea
what is the process of ventilation of the human lungs (inspiration)
-external intercostal muscles contract moving ribs out and up
-outer pleural membrane pulled outwards, reducing the pressure in the plural cavity
-Inner pleural membrane pulled outwards
-Lung surface is drawn out causing alveoli to expand
-Pressure in the alveoli is lower than atmospheric pressure so air moves in
What is the process of ventilation in the human lungs (expiration)?
-external intercostal muscles relax ribs in and down
-outer of pleural membrane moves
outwards
-inner plural membrane moves inwards
-lungs move in causing alveoli to deflate
-Pressure in the alveoli is higher than atmosphere pressure so air moves out
what are the features of alveoli?
-Air in alveolus
-Alveolar Wall
-Capillary Wall
-Erthrocyte
What are they alveoli suitable for gas exchange?
-Large SA- lots of them creating it for diffusion gases
-Thin (one cell thick) short diffusion pathway
-moist so gases can dissolve and diffuse
-extensive capillary network with blood circulating to maintain a diffusion gradient
What is surfactant?
A chemical substance which covers the surface of the alveoli
What does surfactant do?
reduces surface tension and prevents the alveoli from sticking together and collapsing when breathing out
What is the function of the intercostal muscle?
-when they contract, the ribs are pulled up and out, increasing the volume of the thorax
what are bronchioles?
bronchi branch into these small tubes
what is the larynx?
-box shaped structure above trachea, contains vocal cords
what is the alveoli?
Main site of gas exchange, have a large SA
what is the Bronchus?
-Trachea splits into 2 of these
What are the trachea?
-Tubes held open by rings of C-shaped cartilage
what is the function of the ribs?
-these bones are moved by the intercostal muscles and alter the size of the thorax (chest cavity)
What is the diaphragm?
-domed shaped muscle that relaxes and contracts altering the volume of the thorax
What is the pleural cavity?
Contains plural fluid, which acts as a lubricant to reduce friction between the lungs and inside wall of the thorax during ventilation
What is the epiglottis?
-flap of skin that stops food entering the trachea when swallowing
what are pleural membranes?
Act as lubricant, allowing friction, free movement against the inner wall of the thorax
Do Amphibians contain haemoglobin?
No
