Module 3:Exchange Surfaces Flashcards
Is the metabolic activity of single celled organisms high or low?
Is their SA:V ratio high or low?
Low-the oxygen demands and carbon dioxide production is relatively low
High
Is the metabolic activity and SA:V ratio of multicellular organisms high or low?
Metabolic activity is high
Have far greater oxygen demands from the muscle cells etc.
SA:V ratio is much lower , cells at centre of organism are much further away so cant rely on simple diffusion
What are the features of an efficient gas exchange system?
-a large surface area
-have thin walls to provide a short diffusion pathway
-good blood supply and good ventilation to maintain a steep concentration gradient
What components make up the mammalian gas exchange system?
the lungs
the trachea
the bronchi
the bronchioles
nasal passage and mouth cavity
What are the features of the nasal cavity/passage?
3
-large SA with a good blood supply which warms the air to body temp
-a hairy lining which secretes mucus to trap dust and bacteria
-has moist surfaces to increase humidity of incoming air to reduce evaporation from the exchange surfaces
What are the features of the trachea?
2
-a wide tube supported by incomplete rings of strong ad flexible cartilage to prevent it collapsing
-lined with a ciliated epithelium and goblet cells which secrete mucus onto the trachea lining to trap any dust or bacteria , the cilia beat to waft the mucus away from the lungs
What structure are the bronchi similar to , why ?
What is the difference between the two components?
the trachea , because they both contain the incomplete rings of cartilage for support
the bronchi are smaller
What are the other features present in the bronchi?
2
-the inside surface of cartilage is layered with glandular and connective tissue , elastic fibres , smooth muscle and blood vessels
-the inner most lining is an epithelial layer composed of ciliated epithelium and goblet cells
Describe the features of the bronchioles
3
-walls contain smooth muscle and elastic fibres
-the smaller sized ones don’t contain any cartilage and can have alveoli clusters at the end
-they are lined with a thin layer of flattened epithelium which makes some gas exchange possible
Explain how the alveoli create an efficient gas exchange surface
5 points
1)their walls are one cell thick providing a short diffusion pathway
2)contain squamous epithelium which also helps provide a short diffusion pathway
3)contain elastic fibres so can stretch and recoil to help ventilation
4)large number of them in the lungs provides a larger surface area
5)they are very small so can provide a larger SA:V ratio
What does the elastic tissue(collagen and elastic fibres) allow in the alveoli?
What is the name of this function?
they allow them to stretch as air is drawn in and once returned to resting size they help squeeze air out
the elastic recoil of the lungs
What structures are involved in the mammalian gas exchange system
5
-cartilage
-ciliated epithelium
-goblet cells
-smooth muscle
-elastic fibres
What is the function of cartilage?
Which components is it present in?
the trachea , bronchi and some bronchioles
-it acts as a support and prevents the lungs/trachea/bronchi from collapsing due to a pressure drop during exhalation
What is the function of ciliated epithelium?
Where is it found?
involved in moving mucus along towards the throat to prevent lung infection
trachea , bronchi and bronchioles
What is the function of goblet cells?
Where are they present?
Which enzyme is related to its function and how?
they secrete mucus which traps bacteria and dust to prevent it reaching the lungs
trachea , bronchi and bronchioles
lysozyme then digests this bacteria
What is the function of smooth muscle?
it helps to control the flow of air to and from the alveoli by constricting to control the diameter of the airways
What is the function of elastic fibres?
also involved in controlling the flow of air by stretching when we inhale and recoiling when we exhale
What components are involved in the mechanism of ventilation in mammals?
3
the rib cage
the intercostals(internal and external)
the diaphragm
What is meant by the term ventilation?
Name the 2 stages involved
the flow of air in nd out of the lungs as a result of pressure changes in the thorax
inspiration and expiration
Describe the process of inspiration
6 points
(is it active/passive)
its an active process
external intercostals contract and internal ones relax
this forces the rib cage up and out
the diaphragm contracts and flattens
the thoracic volume increases
thoracic pressure decreases so pressure outside the lungs is greater
this creates a pressure gradient so air rushes into the trachea down its pressure gradient
Describe the process of expiration
(Is it active/passive)
its a passive process
the internal intercostals contract and the external ones relax
the diaphragm relaxes and moves upwards
this causes the rib cage to move down and in
the thoracic volume decreases and the thoracic pressure increases which causes air to leave the lungs down its pressure gradient
What does tidal volume mean?
What does vital capacity mean?
the volume of air that moves in and out of the lungs with each resting breath
the largest volume of air that can be breathed in from the strongest possible inhale followed by the strongest possible exhale
What does inspiratory reserve volume mean?
Expiratory reserve volume
the max volume of air you can breathe in over and above your normal inhale
the max volume of air you can force out of your lungs over and above your normal volume of air breathed out
What does residual volume mean?
the volume of air left in the lungs when you have exhaled as hard as possible
What does total lung capacity mean?
How is it calculated?
the total potential volume of air in the lungs at any one time
the sum of your vital capacity and residual volume
What does breathing rate mean?
What does ventilation rate mean?
How is it calculated
the number of breaths taken per minute
the total volume of air inhaled in 1 minute
= tidal volume x breathing rate
Describe the relationship between tidal volume , vital capacity , breathing rate and oxygen uptake
2 points
when the oxygen demands of the body increase , the tidal volume of the lungs per breath can increase from 15% up to 50% of the vital capacity
breathing rate can also increase which increases the ventilation of the lungs and oxygen uptake during gaseous exchange to meet the demands of the tissue
