Respiration Flashcards
what does respiratory pathway consist of ?
. nose . nasal cavity . paranasal sinuses . pharynx . larynx . trachea . bronchi . alveoli
what is the conducting portion of respiratory tract ?
nose through the larger bronchioles
what is the function of conducting portion of respiratory tract ?
. no gas exchange occurs here
. air is cleaned , warmed , moistened
what is in the respiratory part of tract ?
. small bronchioles and alveoli
what happens in the respiratory part of tract ?
. gas exchange
what is the function of nasal cavity ?
. conducts air to the pharynx . contains olfactory receptors . warms air . moistens air . cleans air
why is the air warmed in nasal cavity ?
lung has a big surface air so when you breathe in cold air temperature drops
why does nasal cavity moisten air ?
in order for gas exchange to happen oxygen and carbon dioxide must dissolve so air must be moist
if alveoli was dry, it would not be able to absorb respiratory gases.
why is air cleaned in nasal cavity?
to get rid of dirt and junk in air
what are olfactory receptors?
they line superior region of the nasal cavity
they are bipolar cells
produce action potential
what is the nasal cavity most lined with ?
pseudostratified ciliated epithelium containing goblet cells and nasal glands
what are the nasal glands secretions?
serous and mucous
they also contain antibacterial enzymes such as lysozyme
what is the function of mucous in the nasal cavity ?
traps impurities to clean the air
/they help warm and moisten hair
what is the function of serous secretions in nasal cavity ?
moisten the air
what is the function of superficial blood vessels in nasal cavity?
warm the air
what is the function of cilia ?
the cilia of the nasal epithelium beat moving trapped impurities to the pharynx were they are swallowed (the mucous)- get rid of it.
what happens in cold weather to the beating of cilia ?
beating of cilia slows down and nose drips
what do increased nasal secretions do ?
increased nasal secretions account for stuffed up , runny noses
what is the function of sensory nerve endings?
trigger the sneeze reflex to expel impurities
what is paranasal sinuses ?
air filled spaces/sinues that surround nasal cavity, they also contain blood vessel- (also serve to warm the air)
found in bones around nose
what is the function of paranasal sinuses ?
decrease the weight of skull , they also warm and moisten the air
what happens after air passes through nasal cavity ?
enters the pharynx before entering larynx
what is larynx?
is the complex tube (modified part of the trachea) - which is made of muscle and cartilage.
what is the function of larynx?
muscles contract to vibrate the vocal folds- sound
what is trachea?
10-12 cm long tube connecting the larynx to the primary bronchi
what happens when primary bronchi goes into lungs ?
they subdivide into secondary bronchi and bronchioles
what lies next to trachea ?
oesophagus where food goes through
what is the trachea surrounded by ?
C-shaped cartilaginous rings
what is the function of C-shaped cartilaginous rings that surround trachea?
its c-shaped to allow trachea to change shape
stops trachea collapsing every time we eat
what is the structure of trachea?
. inner surface is covered by mucosa which is ciliated pseudostratified epithelium , goblet cell
. the submucosa contain seromucous glands whose secretion along with goblet cells trap impurities and moisten the air
-the cilia beat to move the trapped impurities to the pharynx- to swallow mucous
. smooth muscle
why is there smooth muscle in trachea?
regulate flow of air by increasing/decreasing diameter of trachea
how does the structure of respiratory tract simplify as one progress downwards from the trachea?
. the cartilaginous rings are simplified to isolated plaques before disappearing
. the epithelium changes form pseudostratified to simple columnar to cuboidal to squamous in alveoli
. the number of goblet cells decrease
. number of cilia also decrease
. elastic fibres remain constant through out system
why cilia still made when there is no mucous ?
mucous falls down due to gravity
what does terminal bronchioles signify ?
the end of the conducting portion of the respiratory tract ?
describe what makes up the respiratory portion of respiratory tract ?
. terminal bronchioles which branch into smaller respiratory bronchioles , which are studded with isolated alveoli
. these lead to alveolar ducts containing more alveoli
. finally leading to alveolar sacs made up of many alveoli
where does gas exchange happen ?
within alveoli
what is the function of pulmonary artery?
delivers deoxygenated blood to the lungs
what does pulmonary artery divide into?
it divides into smaller vessels (arterioles) until each alveolus is covered by a network of capillaries , before blood returns to the heart via pulmonary vein
what is each alveolus surrounded by ?
each alveolus is surrounded by a dense network of capillaries containing oxygenated blood
what are the three types of cells that line the alveoli/separating the air in alveoli from the blood in the capillaries?
- the walls of the alveoli are mostly composed of simple squamous epithelial cells (type 1)
- surfactant secreting cells (type of epithelial cells) (type 2)- produce surfactant
- alveolar macrophages -to protect surface
everything contains elastic fibres/c.t in respiratory system
what is the function of alveolar pores between alveoli ?
equalise the pressure within the lungs
what is function of surfactant?
.contains antimicrobial proteins
. lowers surface tension - this is because water molecules are more attracted to each other than to air/atmosphere , thus when alveoli is emptied of air they tend to collapse and walls stick together making it hard to reinflate
. surfactant ensure that lungs don’t collapse when you breathe in by interfering with cohesiveness of water molecules
what is the air:blood interface?
thin barrier that separates air in alveoli and blood in capillaries
provides a barrier of minimal thickness for the diffusion of oxygen and carbon dioxide- SIMPLE DIFFUSION
what is the size of air:blood interface?
0.5 um
what is the air:blood interface composed of ?
- layer of surfactant
- simple squamous epithelia of alveoli
- basement membranes of alveolar epithelial cells and capillary endothelium
- simple squamous capillary endothelial cells
why is the alveoli lined with fluid?- gas diffusion (at lungs and tissues)
- allowing gases to diffuse and dissolve
- gas will move from an area of high concentration to low concentration
what is daltons law?
in a mixture of gases , the total pressure exerted is equal to the sum of partial pressure of individual gases
what is normal atmospheric pressure?
760mmHg
partial pressure of oxygen is 21% of 760 = 160mmHg
partial pressure of carbon dioxide is 0.3% 0f 760 = 0.3mmHg
explain the partial pressure of oxygen and carbon dioxide in the alveoli compared to the atmosphere?
the partial pressure of oxygen is lower and the partial pressure of carbon dioxide is higher in the alveoli compared to the atmosphere , this is because alveoli contains stale air and oxygen is absorbed while carbon dioxide is given off
why does oxygen diffuse into blood and carbon dioxide into the capillaries ?
blood arriving at the lungs is poorer in oxygen and richer in carbon dioxide than the alveoli
why does oxygen diffuse into tissue and carbon dioxide into blood?
blood arriving at the tissue has a higher partial pressure of oxygen therefore diffusing into tissue and lower partial pressure of carbon dioxide than the tissue
explain what happens to oxygen and carbon dioxide at lungs ?
oxygen diffuses into blood
carbon dioxide diffuses out blood
what happens to oxygen and carbon dioxide at tissue?
oxygen diffuses into tissue
carbon dioxide diffuses out into blood
how is most oxygen transported?
most oxygen is transported in combination with heamoglobin in red blood cells
what is heamoglobin composed off ?
heamoglobin is composed of 4 polypeptide chains , each bound to a heam group
the iron in each heam binds a molecule of oxygen
how is carbon dioxide distributed in the body?
. 7-10% of carbon dioxide is dissolved in the plasma
. 20% is bound to the globin portion of heamoglobin
. 70% is dissolved in plasma as bicarbonate ion
where is the lung located?
the lungs sit in the pleural cavity of the thorax
what are the lungs surrounded by ?
they are surrounded by a double layered serosa - the pleura
what does pleura secrete?
the pleura secretes a fluid that fills the pleural cavity
what is the function of fluid that is secreted by the pleura?
the fluid lubricates the movement of the lungs and surface tension ensures the lungs adhere to the walls of the thorax.
when the thorax moves so do the lungs
what is boyles law?- mechanics of breathing
the pressure of gas is inversely proportional to its volume
so decreasing volume increases collisions and increases pressure
- 2nd law- a gas will move from an area of high pressure to a region of low pressure
what are the 2 main muscles involved in pulmonary ventilation?
. intercostal muscle that join the ribs
. the diaphragm that separates the thorax from abdomen
what happens during inspiration (inhalation)?
. thoracic volume increases
. external intercostal muscles contract , raise the rib cage , expanding the thorax- increasing throaic volume ( front/back direction)
. the diaphragm contract ,flattens expanding the thoracic volume ( up/down direction)
. the pressure in the lungs falls below atmoshperic pressure ( as their volume has increased and pressure decreases)
and air enters the lungs
how much is thoracic dimensions changed by during inspiration?
. thoracic dimensions are only changed by a few mm in each direction , this is enough to change the volume around 500 ml
. during forced inspiration volumes are increases as secondary muscle produce bigger volume
what happens during expiration ( exhalation)
. inspiratory muscles relax and the elasticity of the thorax decreases its volume
. pressure within the lungs increase above atmospheric pressure forcing air out
-passive process
what happens during forced expiration?
abdominal muscle are forced against the diaphragm and internal intercostals pull down the ribs
how is the basic rhythm of respiration is generated?
. is generated in a group of neurons in the pons of the brainstem called the ventral respiratory group (VRG)
. VRG uses pacemaker neuron like in the heart and stomach via a.p
. inspiratory neurons in the VRG stimulate the diaphragm and external intercostal muscle
what is the function of neurons in the dorsal respiratory group (DRG) ?
they receive input from peripheral stretch receptors and chemoreceptors and modulates the rhythm set by the VRG
what is the function of pontine respiratory system (PRC) ?
they modify the activity of VRG ( during speech , sleep and exercise)
how is respiration modulated to suit the body’s need ?
. central and peripheral chemoreceptors respond to low oxygen and high carbon dioxide levels to increase respiration.
. proprioceptors in muscle detect muscle activity(muscles are active) and facilitate respiration
. respiration can be influenced cortically
. stretch receptors in the lungs to inhibit respiration , preventing over inflation
. nociceptors in the lungs detect irritants and cause sneezes , coughs
explain respiratory volumes?
. tidal volume - normal breath
. inspiratory reserve volume - amount of air that can be inspired forcibly beyond tidal volume
. expiratory reserve volume - amount of air that can be expired forcibly beyond tidal volume
. vital capacity - biggest possible breath
. residual volume- air that cannot be expelled
