Gaseous Exchange Flashcards
What is breathing?
A mechanical process of taking oxygen into the lungs
What is cellular respiration?
Cellular respiration refers to a chemical process which takes place within cells in order to release energy
What is gaseous exchange?
Gaseous exchange is a physical process which involves the exchange of gases between the air and the blood in the lungs. Organs are structurally suited to ensure this process is optimised, mammals have a breathing mechanism that ensures the entry of gases in their bodies, this allows gaseous exchange and cellular respiration to occur efficiently
List the important aspects of gaseous exchange.
- Structure to function: how the organism is designed to carry out gaseous exchange
- Regulation and control of breathing in humans
- How the amount of gases are kept at manageable levels in the blood
- Disease and certain life choices can impact negatively on gaseous exchange. Breathing can be impaired which affects the general health of an individual
Define diffusion
The movement of molecules from a region of high concentration to a region of low concentration until equilibrium is reached
Define catabolism
The breaking down of complex molecules into simple molecules to release energy
Define aerobic
Occurring in the presence of oxygen
Define anaerobic
Occurring in the absence of oxygen
Define cellular respiration
The breakdown of organic compounds (glucose/sugar) in the mitochondria of cells into inorganic products (CO2 & H2O) with the release of cellular energy (ATP) ; either aerobic or anaerobic
Requirement: large
Reason: a large surface area to volume ratio allows enough oxygen and carbon dioxide to defuse
Requirement: thin and permeable
Reason: diffusion can occur more rapidly and efficiently if the surface is thin and permeable
Requirement: moist
Reason: oxygen and carbon dioxide diffuse when in dissolved water
Requirement: protected
Reason: all gaseous exchange surfaces need to be protected from mechanical injury as well as from dying out (desiccation)
Requirement: well-ventilated
Reason: ensuring that oxygen rich air for terrestrial organisms and oxygen rich water for aquatic organisms are continually brought into contact with the gaseous exchange surface
Requirement: vascular
Reason: an efficient method of transporting gases to and from the gaseous exchange surfaces is required
The amount of oxygen taken up and carbon dioxide released depends on the ratio of surface area to volume of the organism.
What does this mean?
- Surface area is the combination of all exposed surfaces of the organism
- The volume is the space taken up by the same organism
- Therefore, the surface area to volume ratio would be the amount of surface an organism has relative to its size
Define terrestrial
Organisms that live on land
Define aquatic
Organisms that live in water
Define gaseous exchange
The exchange of oxygen and carbon dioxide at a respiratory surface occurs at two places in mammals:
- at a gaseous exchange surface (lungs) and the blood
- between the blood and the body cells at the tissue level
Define breathing/ventilation
Mechanical process of inhalation and exhalation through which air moves in and out of the respiratory organs enabling the uptake of oxygen and the removal of carbon dioxide
The human gaseous exchange system consists of the following distinct sections:
- air passages
- lungs
- muscles involved in the mechanism of breathing (ventilation)
Structure: 2 nostrils
Function: air inhaled through nostrils
Structure: 2 nasal cavities
Function:
- cavities are lined with epithelial and goblet cells
- mucous from the goblet cells together with the cilia trap dirt and sweep it out of the nose; keeps cavity moist
- blood capillaries warm the incoming air
Structure: trachea
Function:
- windpipe is situated in front of the oesophagus
- c shaped cartilage rings protect the trachea and keep it open for easy movement of air
Structure: bronchus/bronchi
Function:
- trachea branches into the left and right bronchi that enter the upper lobes of the left and right lungs
- held open by O shaped cartilage rings; lined with mucous membranes
Structure: bronchiolus/bronchioli
Function:
- each bronchus divides into many branches, the bronchioli
- these passages are smaller and narrower and do not have cartilage for reinforcement
Structure: alveoli
Function:
- bronchioli end in a collection of alveoli (air sacs) that are sites for gaseous exchange
- many alveoli increase the surface area to maximise the gas exchange
- have thin wallah of squamous epithelial cells allowing for easy diffusion of gases
- tissue fluid keeps the walls of the alveoli moist
- a large blood capillary network surrounds the alveoli
Structure: pharynx
Function:
- connects the nasal cavity with the larynx
- lined with mucous membranes
- leads into the trachea and the oesophagus
Structure: larynx
Function:
- larynx contains the vocal cords
- air passes over the chords and sound is protected
Structure: epiglottis
Function:
- a cartilage structure on top of the larynx (voice box)
- closes when food is swallowed preventing food from entering the trachea
Structure: lungs
Function:
- each of the two spongy, elastic lungs are surrounded by the double pleural membrane
- pleural fluid acts as lubricant and helps prevent friction during inhalation and exhalation
Structure: ribs
Function:
-on either side of the sternum, protect the lungs from injury
Structure: intercostal muscles
Function:
- found between the ribs
- contract and relax during inhalation and exhalation altering the volume of air in the chest (thoracic cavity)
Structure: diaphragm
Function:
- a sheet of muscle below the lungs
- contracts and flattens altering the volume of the chest cavity and is important in breathing
