The mammalian gases exchange system 7.2 Flashcards
why are gases exchange surfaces moist and what is the problem with this
so oxygen dissolves in the water before diffusing into the body tissues.
As a result for the conditions needed to take in oxygen successfully are also ideal for the evaporation of water
where does the exchange of gases take place in human
in humans it takes place in the lungs
What are the important features of the nasal cavity
- large surface area with good blood supply
- secretes mucus to trap debris and pathogens
- Moist surfaces
what is the trachea
- main airway carrying clean, warm, moist air from the nose into the chest.
what is the structure of the trachea
- wide tube supported by incomplete rings of strong, flexible cartilage
^stop trachea from collapsing
^rings incomplete so food can move easily down the oesophagus - lined with ciliated epithelium and goblet cells
what is the function goblet cells and cilia in the trachea
- goblet cells produce mucus to trap debris and pathogens
- cillia beat in rhythmic pattern to move away mucus
how does cigarette smoke effect cilia
1 of the effects of cigarette smoke is that it stops cilia beating
what path does the air involved in gaseous exchange in humans take through the human body
Nasal cavity
trachea
bronchus
bronchioles
alveoli
- what is the bronchus structure
- what is the function
- where can you find it in the body
- trachea divide to form the bronchus
- found in the lungs
- tubes with supporting ring of cartilage but are smaller than trachea
- carry air from trachea to the bronchioles
- what are bronchioles split from
- what is there structure and how does this aid there function
- bronchi divide to form small bronchioles.
- have no cartilage rings.
- there walls contain smooth muscle
^can contract and relax, so vol of air reaching lungs is influenced - lined with thin layer of flattened epithelium which makes some gaseous exchange possible
what is the alveoli structure and function and where can you find it in the body
- tiny air sacs
- main gas exchange surface
- Each alveolus consists of layer of thin, flattened epithelial cells, along with some collagen and elastic fibres
what is meant by the elastic recoil of the lungs
The elastic tissues in the alveoli allow the alveoli to stretch as air is drawn in. When they return to their resting size, they help squeeze the air out.
How is the surface area in the alveoli adapted for effective gaseous exchange
large surface area
there are 300-500 million alveoli per adult lung. The alveolar surface area for gaseous exchange in the 2 lungs combined is around 50-75 m^2 which is larger than the average floor area of a house at 67m^2
How are the layer of cells in the alveolus adapted for effective gaseous exchange
they have thin layers
both the alveoli and the capillaries that surround them, have walls that are only a single epithelial cell thick, so the diffusion distance between the air in the alveolus and the blood in the capillaries are very short
How is the blood supply for alveoli adapted for effective gaseous exchange
- Good blood supply
- supplied by network of capillaries.
- constant flow of blood maintains steep concentration gradient for both CO2 and O2
How is ventilation adapted in the alveoli for effective gaseous exchange
Good ventilation
breathing moves air in and out of the alveoli, helping maintain steep diffusion gradients for oxygen and carbon dioxide between the blood and the air in the lungs
How are the alveoli adapted for effective gaseous exchange
Large surface area
Thin layers
Good blood supply
Good ventilation
what is the inner surface of alveoli covered in
The inner surface of the alveoli is covered in a thin layer of a solution of water, salt and lung surfactant
what are the pros and cons of the solution lining the inner surface of the alveoli
the lung surfactant makes it possible for the alveoli to remain inflated.
Oxygen dissolves in the water before diffusing into the blood
Water can also evaporate into the air in the alveoli
How are the lungs ventilated
changes in volume and pressure in the thorax drawws air into and out of the lungs
what does inspiration mean
taking air in or inhalation is an energy using process
Name all the sections of the thorax involved in ventilation and where are they found
The rib cage provides a semi-rigid case within which pressure can be lowered with respect to the air outside it.
The diaphragm is a broad, domed sheet of muscle which forms the floor of the thorax.
The external intercostal muscles and the internal intercostal muscles are found between the ribs.
The thorax is lined by the pleural membranes, which surround the lungs.
The space between them, the pleural cavity, is usually filled with a thin layer of lubricating fluid so the membranes slide easily over each other as you breathe
how does the process of inspiration occur
diaphragm contracts, flattening and lowering.
external intercostal muscles contract, moving the ribs upwards and outwards.
this increases volume decreasing pressure compared to atmospheric air so air moves into lungs
what is expiration
Breathing out or exhalation is a passive process
How does the process of expiration work
passive
diaphrgam relaxes moving up, external intercostal muscles relax, rib cage moves down and in, elastic fibres in alveoli reuturn to normal shape
forcible expiration
internal intercostal muscles contract pulling ribcage in and down fast, abs contract forcing diaphragm up
all of these decrease volume and increase pressure so air is pushed out of lungs
How much more force is needed for your first breathe
The first breathe of a newborn baby takes needs a force 15-20 times greater than any normal inhalation to inflate the lungs. The lungs are enormously stretched as the air flows in, and the elastic tissue never returns to its original length
What does the lung surfactant important for the alveoli
Lung surfactants contain phospholipids and both hydrophilic and hydrophobic proteins. The surfactant stops the alveoli collapsing and sticking together as you take your first breathe, without it your second breath would be as hard as your first breathe and breathing would be impossible
