Exchange Surfaces and Breathing Flashcards
Why is diffusion alone, enough to supply the needs of single celled organisms?
- the metabolic activity of a single celled organism is usually low and the need for oxygen even lower
- the SA:V ratio of the organism is large
What are the 4 examples of things an effective exchange surface has?
- increased surface area
- thin layers (faster rate of diffusion)
- good blood supply (to maintain the concentration gradient)
- ventilation to maintain diffusion gradient
What is the human exchange system called?
gaseous exchange system
Why do mammals e.g. humans need a high volume of oxygen and be able to get rid of c02 quickly?
they have a small SA:V ratio
they have a high metabolic rate (in order to maintain body temp independent of the environment)
need for respiration
The Nasal cavity involves the first step of the human gas exchange system. How does it work?
- large SA, good blood supply, warms body temp
- hairy lining, secretes mucus and protects lungs from irritation and infection
The trachea involves the second step to the human gas exchange system. How does it work?
Wide tube which is supported by rings of cartilage (stops the trachea from collapsing)
the rings are incomplete so that the food can move down the oesophagus behind trachea
trachea lined with ciliated epithelium with goblet cells between and below the epithelial cells
What do goblet cells do?
secrete mucus onto lining of trachea, cilia beat and move the mucus, along with trapped dirt and microorganisms
The third step in the human exchange system is the Bronchus. How does it work?
they are similar structure to the trachea , with supporting rings of cartilage but smaller
The fourth step in the human gas exchange system is the bronchioles? How do thy work?
(1mm diameter or less)
inner walls contain smooth muscle, when muscle contracts they constrict and close, when the muscles relax they dilate
Changes the amount of air reaching the lungs
The final step in the human gas exchange system is the alveoli? How do they work?
tiny air sacs, each one consists of a layer of thin, flattened epithelial cells, along with some collagen and elastic fibres
Allow to stretch to air in
What are the main adaptations of the alveoli for effective gaseous exchange?
- Large surface area - 300 - 500 million per adult lung, large SA:V ratio
- Thin layers, capillaries and alveoli are one cell thick, shorter diffusion distance between the air and the blood
- good blood supply
- good ventilation
What is lung surfactant?
Makes it possible for the alveoli to remain inflated, located on the inner surface of the alveoli of water and salt and lung surfactant
What is the difference between internal and external intercostal muscles?
internal = inside
external = outside
Inspiration is an energy using process. What is it?
- the dome shaped diaphragm contracts, flattening
- external intercostal muscles contract , moving ribs upwards and outwards
- volume of the thorax increases so pressure is reduced
- pressure is lower than the atmospheric air, so air is drawn in
- travels down the conc gradient to reach equilibrium
Expiration is a passive process. How does it work?
- muscles in the diaphragm relax, into a dome shape
- external intercostal muscles relax, causing gravity to move the ribs down and inwards
- the elastic fibres in the alveoli return to normal length
- this decreases the volume of the thorax
- pressure inside the thorax is greater than the atmospheric air so air is forced outwards to reach equilibrium
What are the three methods used for measuring the capacity of the lungs?
- peak flow meter
- vitalograph
- spirometer
What is tidal volume?
volume of air that moves into and out of the lungs with each resting breath
What is vital capacity?
volume of air that can be breathed in when deepest inhalation and deepest exhalation
What is meant by inspiratory reserve volume?
max volume of air you can breathe in over and above normal
What is meant by expiratory reserve volume?
extra amount of air you can force out of your lungs over and above normal
What is meant by residual volume?
volume of air that is left in your lungs when exhaling as hard as possible (can’t be measured directly)
What is meant by total lung capacity?
sum of the vital capacity and the residual volume
What is meant by breathing rate?
number of breaths taken per minuet
How do you calculate the ventilation rate?
tidal volume x breathing rate
How does a peak flow meter work?
what you use to measure the rate at which air is expelled e.g. when you have asthma
Why can no gaseous exchange take place in insects?
they have a tough exoskeleton
How does gas exchange take place in insects?
along thorax and abdomen, there are small openings known as spiracles
air moves in and out of these as well as water
What open and close the spiracles in insects?
the spiracle sphincters (used to prevent water loss)
What structure leads away from the spiracles and what does it do?
The tracheae, large tubes in the respiratory system
run both into and along the body
lined with chitin (which makes up the cuticle)
relatively impermeable to gases
The tracheae branches to form what and what does it do?
tracheoles, single elongated cell, no chitin so permeable to gases
they are so small spread throughout tissue running between cells
gas exchange takes place
What is located at the end of tracheoles and what does it do?
tracheal fluid, which limits the penetration of air for diffusion
when oxygen is low, lactic acid can build up causing the water to spread out more, more efficient gas exchange
When insects have a higher energy demand, the may use mechanical ventilation of the tracheal system. How does this work?
air actively pumped into the system by muscular pumping system in the thorax, causes pressure changes
air is forced in/out
How does having collapsible enlarged trachea/ air sacs help gas exchange?
they are used to increase the amount of air moved, they can be inflated/deflated by ventilating movements of the thorax/abdomen
What is the meaning of viscosity?
thickness
How are gills adapted and what is the role of them in the fish respiratory system?
they maintain the flow of water in one direction over the gills.
They have a large surface area, good blood supply and thin layers to allow faster rate of diffusion
What is an operculum?
(a bony flap), which is also active in maintaining a flow of water over the gills
What are the gill lamellae?
with their rich blood supply and large surface area, are the main site of gaseous exchange in the fish
What are the gill filaments?
occur in large stacks (gill plates) and need a flow of water to keep them apart
What is another name for a fish mouth?
buccal cavity
What happens when the buccal cavity is opened? (the start of ventilation)
the mouth opens and the buccal cavity is lowered, increasing the volume of the cavity = the pressure inside the cavity drops allowing water to move in
opercular valves shut and the gills expand
