gaseous exchange Flashcards
Distinguish between breathing, gaseous exchange and cellurar respiration
breathing is the mechanical process whereby air moves in and out of the lung
gaseous exchange is a physical process which involves the exchange of gases between the air and the blood in the lungs
cellular respiration is a chemical process which takes place within the cells in order to release energy
Requirements for for an effective gaseous exchange system
the gaseous exchange surface must :
- be large to maximize the gaseous exchange
- be thin for quick and easy diffusion
- be moist because oxygen and carbon dioxide must be in solution to diffuse through a membrane
- be having a transport system for efficient transport of gases
- be well protected because it is very thin and fragile
the movement of molecules from a high concentration to a low concentration until equilibrium is reached
diffusion
the air passage,lungs and respiratory muscles are part of this system
he human respiratory sysyem
the air passage
it transports air to and from the lungs ,
it consists of the nasal cavity, pharynx,trachea,bronchi an bronchioli and alveoli
the nasal cavity
it has 2 external nostrils that lead to the two nasal cavities. # small hairs in the nasal cavity filter large particles from the inhaled air.
how is the nasal cavity adapted to suit its function
it is lined with a mucous membrane that is line up with cilliated columnar epithelial cells
+ the columnar epithelial cells are richly supplied with superficial blood capillaries the warm the incoming air
+ goblet cells in the columnar epithelial secret mucus
+ the mucus -traps ducts and germ particle
-it is also antiseptic and prevents inhaled
germs from multiplying
-moistens the incoming air
+ the cilia on the columnar epithelial continuously performs sweeping movements in the direction away from the lungs
the pharynx
- connects the nasal cavity with the larynx
- it is lined with a mucus membrane
- it leads to 2 openinngs: the glottis that leads to the trachea and the oesophagus
how is the pharynx’s membrane adapted to suits its functions
it is lined with a mucous membrane that is line up with cilliated columnar epithelial cells
+ the columnar epithelial cells are richly supplied with superficial blood capillaries the warm the incoming air
+ goblet cells in the columnar epithelial secret mucus
+ the mucus -traps ducts and germ particle
-it is also antiseptic and prevents inhaled
germs from multiplying
-moistens the incoming air
+ the cilia on the columnar epithelial continuously performs sweeping movements in the direction away from the lungs
trachea
^it is a long , tubular structure the is located in-front of the oesophagus
^ The larynx is located at the top of the trachea
^ the epiglottis is a leaf-shaped cartilage structure that closes when food is swallowed, preventing food from entering the trachea and choking
^ C-shaped cartilage ring protects the trachea and keeps it open for easy movement of air
^it is also lined with cilliated columnar epithelial cells
bronchi and bronchioli
& the trachea divides into the left and right bronchus that enters the lungs respectively
$ the bronchi are lined with a mucous membrane and held open by o-shaped cartilage rings
inside the lung, the bronchi branches into bronchioles and loses their cartilage
$ each bronchioli ends in an infundibulum which consists of groups of alveoli
alveoli
- they are site for gaseous exchange
- the many alveolis increase the surface area to maximize gaseous exchange
- they have this walls of squamous epithelial cells allowing for easy diffusion of gases
- tissue fluids keep the walls of the alveolis moist
- a large blood capillary network surrounds the alveolis
- the walls of the capillaries consits of a single layer endothelium
lungs
- lungs are spongy and elastic
- they are surrounded and protected by 12 pairs of ribs
- intercostal muscles are found between the ribs
- the right ling has 3 lobes
- the left lung has 2 lobes
- surrounded by a double pleura membrane
- intrapleural fluid between the 2 pleura membranes acts as a lubricant and helps prevent friction during inhalation and exhalation
- the lungs are conical and rest the bottom on a dome-shaped muscle plate called the diaphragm
adaptions of the lungs for their functions
- lungs are spongy and elastic- can expand and contrast easily during breathing
- lungs are surrounded by a double pleura membrane, with intrapleural fluid between the 2 membrane - prevents friction during breathing
- Bronchioli eventually ends in millions of alveoli- increases the gaseous exchange sites
- the wall of the alveolus consists of a single layer of squamous epithelium- thin surface for efficient gaseous exchange
- alveoli are surrounded by a network of blood capillaries-transports of oxygen to the tissue and carbon dioxide to the lungs
- walls of blood capillaries consist of a single layer of endothelium - thin surface for efficient gaseous exchange
respiratory muscles
Diaphragm- it is a dome shaped muscle plate that separates the chest and abdomen to form a airtight thoracic cavity
Intercostal muscles- the are located between consecutive rib and consists of two sets
- external intercostal muscles
- internal intercostal muscles
red blood cells
erythrocytes
hemoglobin
oxygen carrying protein pigment in the blood
iron
the element found in the hemoglobin molecule to which oxygen atom bonds
what happens during inhalation
- The diaphragm contrast and the thoracic cavity enlarges from top to bottom
- the external intercostal muscles contrast causing the ribs to move upwards and outwards
- the thoracic cavity enlarges from side to side and front to back
- the abdominal muscles relax so that the abdominal cavity can accommodate the viscera being pushed down by the diaphragm
- the total volume of the thoracic cavity is increased and the pressure in the thoracic cavity and lungs decreases
- the elastic lung expands
- since the atmospheric pressure is higher than the pressure in the thoracic cavity and the lungs, oxygen rich air flows into the lungs
explain why inhalation is considered an active process
inhalation is associated with contraction of the diaphragm and external intercostal muscles, which increases the volume of the thoracic cavity
what happens during exhalation
- the diaphragm relaxes and returns to original position while the thoracic cavity becomes smaller from top to bottom
- the external intracostal muscles relaxes causing the ribs to move down and inward
- the thoracic cavity reduces in size and the total volume of the thoracic cavity is reduced while the pressure increases in the thoracic cavity and the lungs
- since the pressure in the chest cavity and the lungs is higher than the atmospheric pressure, carbon dioxide rich air flows out of the lungs
explain why exhalation is considered as a passive process
exhalation is associated with the with the relaxation of the diaphragm and the external intercostal muscles, which decreases in the volume of the thoracic cavity
gaseous exchange in the alveoli in detail ( external gaseous exchange)
- the air entering the the alveoli from inhalation has a high oxygen concentration compared to the oxygen concentration in the blood of the surrounding capillaries
- this results in oxygen diffusion from the alveoli into the blood and carbon dioxide from the blood and back into the alveoli. THEREFORE gases are exchanged due to concentration gradient
- Deoxygenated blood comes from the heart and past the alveoli has a low oxygen concentration
- Oxygenated blood leaves the alveoli with a high concentration of oxygen
- The blood will take the oxygen to the cells where it is need
- the air in the alveoli will be exhaled with more carbon dioxide than the air that is inhaled
explain the the transport of respiratory gases occur
Oxygen is transported by erythrocytes since most oxygen combines with haemoglobin present in the erythrocytes to form OXYHAEMOGLOBIN. it is transported via the circulatory system to all body cells
most of the carbon dioxide is transported in the blood plasma as BICARBONATE IONS and also combines with haemoglobin to form CARBOMINOHAEMOGLOBIN
