TOPIC 7 : EXCHANGE AND TRANSPORT Flashcards
3.1.1 SPECIALISED EXCHANGE SYSTEM
How do you calculate the surface area to volume ratio for a cube?
OF A CUBE:
volume : 1 X 1 X 1 = 1cm3
surface area = 6 X 1 X 1 = 6cm2
6 BECAUSE A CUBE HAS 6 SIDES AND 1CM IS THE MEASUREMENT OF EACH LENGTH, WIDTH AND HEIGHT
6:1
3.1.1 SPECIALISED EXCHANGE SYSTEM
What is the equation for the volume of a cylinder, volume of a sphere and area of a sphere?
pie X radius (squared) X height = volume of cylinder
volume of a sphere = 4/3 pie R cubed
area of a sphere = 4 pie R squared
3.1.1 SPECIALISED EXCHANGE SYSTEM
Why do multicellular organisms need a specific exchange surface?
Diffusion alone would be too slow
the bigger the organism the smaller its surface area to volume ratio
higher demand for substances as activity levels are higher - more metabolically active
layers of cell and tissues - so there is a larger distance between the cells and the external environment
3.1.1 SPECIALISED EXCHANGE SYSTEM
What is an exchange surface?
Specialised area that is adapted to make it easier for molecules to cross from one side of the surface to the other
3.1.1 SPECIALISED EXCHANGE SYSTEM
What are the features of a good exchange surface?
large surface area
large surface area to volume ratio
thin, permeable barrier
maintenance of steep concentration or diffusion gradient
- good blood supply
- good ventilation mechanism (gas exchange)
3.1.1 SPECIALISED EXCHANGE SYSTEM
Why is a large surface area good feature?
Because it can increase their efficiency
3.1.1 SPECIALISED EXCHANGE SYSTEM
Why is it being thin a good feature?
decreases the distance that the substances being exchanged have to travel over, and so improve efficiency
3.1.1 SPECIALISED EXCHANGE SYSTEM
Why is a good blood supply and/or ventilation a good feature?
to increase efficiency
3.1.1 SPECIALISED EXCHANGE SYSTEM
What is the importance of surfactant?
surfactant forms a thin film that covers the alveoli and reduces the surface tension
this reduces the alveoli’s tendency to collapse and reduce the risks of the lugs collapsing
overall, surfactant allows humans to inspire and expire easier
3.1.1 SPECIALISED EXCHANGE SYSTEM
What is a pleural cavity?
each lung surrounded by a pleural cavity which is lined by two pleural membranes (pleural)
the pleural secrete pleural fluid into the cavity
his helps to lubricate and prevent friction during breathing movements
3.1.1 SPECIALISED EXCHANGE SYSTEM
How does forced expiration work?
Normal expiration is a passive process - it doesn’t require energy
Forced expiration is an active process - it requires additional energy
The internal intercostal muscles contract, pulling the ribs down hard and fast, the abdominal muscles contract, forcing the diaphragm up to increase the pressure in the lungs rapidly
3.1.2 GAS EXCHANGE IN MAMMALS
Explain the structure of the gaseous exchange system
as you breathe in, air enters the trachea
the trachea splits into two bronchi - one leading to each lung
each bronchus then branches off into smaller tubes called bronchioles
the bronchioles and in small ‘air sacs’ called alveoli
this is where gases are exchanged
there are lots of alveoli in the lungs to provide a large surface area for diffusion
the ribcage, intercostal muscles and diaphragm all work together to move air in and out
3.1.2 GAS EXCHANGE IN MAMMALS
What is the role of cartilage in the lungs?
supports the tranchea and bronchi; holding the open
in the tranchea there is a C shaped cartilage rings to allow flexibility when turning the neck and to allow the oesophagus to expand when swalling food
stops the tranchea and the bronchi collapsing when you beath in and the pressure drops
3.1.2 GAS EXCHANGE IN MAMMALS
What is the role of smooth muscle in the lungs?
can contract to constrict the airways therby allowing fine control of air/ resistance to airflow and air can move in and out of the lungs more easily
3.1.2 GAS EXCHANGE IN MAMMALS
What is the role of elastic fibres in the lungs?
stretch and recoil
in the airways this helps to dilate the airways after constriction
also helps to push air out of the airways on exhaltation
prevents alveoli from bursting
3.1.2 GAS EXCHANGE IN MAMMALS
What is the role of gobet cells in the lungs?
secrete mucus which traps particles such as dirt and bacteria in the inhaled air and stopping them from reaching the alveoli
3.1.2 GAS EXCHANGE IN MAMMALS
What is the role of ciliated epithelium in the lungs?
have cillia which beat in a synchronised way to waft mucus up the airways to the mouth to be swallowed or removed
prevents lung infections
3.1.2 GAS EXCHANGE IN MAMMALS
The differences between each structure of trachea, bronchi, larger bronchioles, smaller bronchioles and smallest bronchioles and the alveoli and its components
TRANCHEA:
cartilage - yes
smooth muscle - yes
elastic fibres - yes
ciliated epithelium - yes
goblet cells - yes
BRONCHI:
cartilage - yes
smooth muscle - yes
elastic fibres - yes
ciliated epithelium - yes
goblet cells - yes
LARGER BRONCHIOLES:
cartilage - no
smooth muscle - yes
elastic fibres - yes
ciliated epithelium - yes
goblet cells - yes
SMALLER BRONCHIOLES:
cartilage - no
smooth muscle - yes
elastic fibres - yes
ciliated epithelium - yes
goblet cells - no
SMALLEST BRONCHIOLES:
cartilage - no
smooth muscle - no
elastic fibres - yes
ciliated epithelium - no
goblet cells - no
ALVEOLI:
cartilage - no
smooth muscle - no
elastic fibres - yes
ciliated epithelium - no
goblet cells - no
3.1.2 GAS EXCHANGE IN MAMMALS
What is the function of the cartilage in the breathing ducts?
Provides support to the trachea and bronchi, preventing them from collapsing when then the air pressure inside is low during/after expiration
3.1.2 GAS EXCHANGE IN MAMMALS
Why is the cartilage in the trachea C-shaped?
To provide support
more flexibility
allows the trachea to maintain its airways open while still allowing the oesophagus to expand when swallowing food
3.2.2 GAS EXCHANGE IN MAMMALS
Why isn’t the cartilage in the bronchi a complete ring?
no flexibility is required - the bronchi are not placed near to the oesophagus
3.2.2 GAS EXCHANGE IN MAMMALS
What is the function of the smooth muscle in the airways?
allows the diameter of the airways to be controlled
3.2.3 VENTILATION IN MAMMALS
What is ventilation?
consists of inspiration and expiration
it’s controlled by the movements of the diaphragm, intercostal muscles and ribcage
3.2.3 VENTILATION IN MAMMALS
How does inspiration work?
the external intercostal and diaphragm muscles contract
this causes the ribcage to move upwards and outwards and the diaphragm to flatten, increasing the volume of the thorax
as the volume of the thorax increases, the lung pressure decreases
this causes air to flow into the lungs
inspiration in an active process
^^ textbook notes
air brushes into lungs as atmospheric pressure now greater than pressure in thorax
air moves down the pressure gradient
diaphragm contracts
diaphragm flattens and moves down
volume of the thorax increases
^^ class notes
3.2.3 VENTILATION IN MAMMALS
How does expiration work?
the external intercostal and diaphragm muscles relax
the ribcage moves downwards and inwards and the diaphragm becomes curved again
the thorax volume decreases, causing the air pressure to increase
air is forced out of the lungs
normal expiration is a passive process - it doesn’t require energy
The internal intercostal muscles contract, pulling the ribs down hard and fast, the abdominal muscles contract, forcing the diaphragm up to increase the pressure in the lungs rapidly
^^ textbook notes
pressure in the thorax increases
air brishe out of lungs as atmospheric pressure now lower than pressure in thorax
diaphragm relaxes
diaphragm bulges upwards
volume of thorax decreases
^^ class notes
3.2.3 VENTILATION IN MAMMALS
What are the precautions for a spirometer practical?
ensure the spirometer is airtight
use medical grade oxygen and sufficient volume in chamber
check health of the subject
disinfect mouthpiece between each subject
3.2.3 VENTILATION IN MAMMALS
What is the definition of a tidal volume?
the volume of gas exchanged during one breath
3.2.3 VENTILATION IN MAMMALS
What is the definition of a vital capacity?
maximum volume of air that can be exchanged during on breath
3.2.3 VENTILATION IN MAMMALS
What is the definition of a residual volume?
the volume of gas remaining in the lungs after forced expiration
this cannot be expelled
3.2.3 VENTILATION IN MAMMALS
What is the definition of a breathing rate?
number of breaths taken per unit time (usually per minute)
3.2.3 VENTILATION IN MAMMALS
What is the definition of a oxygen uptake?
the rate at which a person uses up oxygen (dm3/minute)
3.2.3 VENTILATION IN MAMMALS
How do use spirometers?
chamber filled with medical grade oxygen floats on tank of water
subject wears a nose clip to ensure breathing through mouth only so exhaled gas returns to tank only and not to be atmosphere
subject breaths in, takesin gas from chambers so chamber volume decreases and chamber moves down - pen on kymograph moves down with chamber
subject breathes out exhales gas into chamber so chamber volumes increases chamber moves up - pen on kymograph moves upwith chamber
kymograph turns slowly to give spirometer trace
soda lime absorbs carbon dioxide from exhaled air
over time overall volume in chamber decreases as subject takes up oxygen and carbon dioxide absorbed
traces falls over time
3.2.3 VENTILATION IN MAMMALS
Suggest a chemical that could be used in a spirometer to absorb carbon dioxide
soda lime
3.2.1 SPECIALISED EXCHANGE SYSTEM?
How does gas exchange work in the alveoli
the alveoli are the gas exchange surface in the lungs
each alveolus is made from a single layer of thin, flatt cells called the alveolar epithelium
O2 diffuses out of the alveolar space into the blood
CO2 diffuses in the opposite direction
the thin alveolar epithelium helps to decrease the distance over which O2 and CO2 diffusion takes place, which increases the rate of diffusion
3.2.1 SPECIALISED EXCHANGE SYSTEM
What are the features of an alveoli?
the alveoli are surrounded by a large capillary network, giving each alveolus its own blood supply
the lungs are also ventilated so the air in each alveolus is constantly replaced
good blood suppy to maintain a steep diffusion gradient
capillary wall is only one cell thick, so short diffusion distance
spherical shape of alveolus gives larger surface area to volume ratio = increases rate of diffusion
good ventilation system to maintain a steep diffusion gradient
layer of surfactant enables gases to dissolve which ^ rate of diffusion
many alveoli gives a large surface area
3.2.1 SPECIALISED EXCHANGE SYSTEM
How are gills adapted for gas exchange?
contains a large network of capillaries - this keeps them well - supplied with blood
they’re also well-ventilated - fresh water constantly passes over them
these features help to maintain a concentration gradient of O2 - increasing the rate at which O2 diffuses into the blood
3.2.1 SPECIALISED EXCHANGE SYSTEM
Why is diffusion across the outer membrane too slow for multi-organisms?
some cells are deep within the body - there’s a big distance between them and the outside environment
larger animals have a low surface area to volume ratio - its difficult to exchnage enough substances to supply a large volume of animal through a relatively small outer surface
multicelluar organism have a higher metabolic rate than single-celled organisms, so they use up oxygen and glucose faster
3.2.1 SPECIALISED EXCHANGE SYSTEM
Why is that singl-celled organisms diffusion rate faster?
substances can diffuse directly into the cell across the cell surface membrane
the diffusion rate is quick because of the short distances the substance have to travel and because single-celled organisms have relatively high surface are : volume ratio
3.2.4 GAS EXCHANGE IN FISH AND INSECTS
How does ventilation and gill irragtion work?
the cylce of gill irrigation strats by the fish opening it’s mouth which lowers the floor of it’s buccal cavity
water flows into the buccal cavity
the fish closes it’s mouth which raises the floor if it’s buccal cavity
this makes the volume of its buccal cavity smaller so therefore the pressure increases
this forces the water over the gills
the fish opens its mouth again and the sides of the operculum bulge out
this increases the volume of the opercula cavity which decreases the pressure so water is drawn over the gills
the opercula flaps open and the water passes out
the flaps then closes again
the fish opens it’s mouth and the cycle begins again
3.2.4 GAS EXCHANGE IN FISH AND INSECTS
How does ventilation in insects work?
respiratory system is not linked to the circulatory system
insects have an open circulatory system - fluid is not in vessels
cells are bathed by haemolymph
gases obtained by diffusion
3.2.4 GAS EXCHANGE IN FISH AND INSECTS
How does the tracheal system?
air enters insect body via spiracle - valve like openings in exoskeleton
air flow can be regulated by small muscles which can open or close the spiracle
each spiracle leads into a network of TRANCHEA
the trancheae subdivide leading to tracheoles
gases diffuse through the network of tubes
3.2.4 GAS EXCHANGE IN FISH AND INSECTS
How does tracheoles and air sacs work?
tracheoles are the site of exchange between the respiratory system and the cells
tracheoles are filled with fluid so oxygen dissolves and then diffuses into the cytoplasm of cells whilst carbon dioxide diffuses from the cell into the tracheole
air sacs in the system provide a reserve of air
useful to conserve water
as spiracles can be closed under high evaporation stress to reduce water loss
3.2.4 GAS EXCHANGE IN FISH AND INSECTS
How does ventilation work?
small insects rely on diffusion
large insects use their abdominal muscles to flush air through the tracheal system whilst opening some spiracles and closing others
3.2.4 GAS EXCHANGE IN FISH AND INSECTS
What is the structure of gills?
water containing oxygen, enters the fish through its mouth and passes out through the gills
each gill is made of lots of thin plates called gill filaments or primary lamellae which gives a big surface area for exchange of gases = ^ the rate of diffusion
the gill filaments are covered in lots of tiny structures called gill plates or secondary lamellae = ^ surface area even more
each gill is supported by a gill arch
the gill plates have lots of blood capillaries and a thin surface layer of cells to speed up diffusion between the water and the blood
3.2.4 GAS EXCHANGE IN FISH AND INSECTS
What is a counter-current system?
in the gills of a fish, blood flows through the gills plates in one direction and water flows over in the opposite direction
3.2.4 GAS EXCHANGE IN FISH AND INSECTS
How does the counter-current system work?
means water with a relatively high oxygen concentration always flows next to blood with a lower concentration of oxygen
this in turn means that a steep concentration gradient is maintained between the water and the blood - so as much oxygen as possible diffuses from the water into the blood
