respiration part 2 Flashcards
Insects:
what are characteristics about their Tracheal system?
- air filled tubes called tracheae
- opens to outside via spiracle
- tracheae branch to form tracheoles
- contact abdominal muscles or thorax for tidal of unidirectional air flow
- gases diffuse n and out
- do not use circulatory system to deliver gas
Birds:
characteristics of lungs?
Stiff and change little in volume
lungs are between a series of air sacs that act as bellows
Birds
where does gas exchange occur?
Occurs as air flows through air capilaries in lungs
air flow through parabronchi is unidirectional
blood flow is crosscurrent and counter current
Mammals:
what are the two parts of the respiritory system?
Upper:
mouth, nasal cavity, pharynx, trachea
lower:
bronchi and gas exchange surfaces (alveoli)
Mammals:
where is the site of gas echange?
alveoli type 1
thin walled
mammals:
Types 2 alveoli do what?
Secrete surfactant
Mammals:
what is surfactant?
Lipids and protein reduce surface tension, prevent alveoli from collapsing, reduces work of breathing
mammals:
what is the outer surface of alveoli covered in?
capillaries
Surface tension and surfactants:
Surface tension is the force acting to do what?
acting to pull liquid’s surface molecules together at an air-liquid interphase
What do surfactants reduce?
Reduce surface tension, thus less work is required to expand the alveolar volume
Pleural Sac:
what do they surround?
each lung
Pleural Sac:
characteristics of them?
two layers of cells with small space between them
Pleural Sac:
What is the Plural cavity have in it?
Pleural cavity contains a small volume of pleural fluid
Pleural Sac:
What is intrapleural pressure?
In subatmospheric
keeps lungs expanded
Mammalian tidal ventilation: Inspiration
what are the steps in inhilation?
motor neurons stimulate inspiratory muscles
contractions of the external intercostals and diaphragm
ribs move outwatrd and the diaphragm moves downward
volume of thorax increase: intrathoracic pressure decrease
decrease in intrapleural pressure
transpulmonary pressure gradient increse
lungs expand, decrease alveolar pressure and air is pulled in
Mammalian tidal ventilation: Exhalation
Steps of exhalation
Nerve stimulation of inspiratory muscles stops
muscles relax
rebs and diaphragm return to their original positions
intrapleural pressure increase
volume of thorax decrease intrathoracic pressure increase
passive recoil of the lungs decrease lung volume which increase alveolar pressure and results in air flowing out of lungs
during reapid, heavy breathing, forced exhalation is by contracting of the internal intercostal muscles
Lung copliance and elasticity:
what is Lung compliance
How easily the lungs strech during inhalation
surface tension in alveolar fluid decrease compliance
Lung copliance and elasticity:
Surfactants do what>
Reduce surface tension by disruptiong the cohesive forces between waer molecules; increase compliance
reduces tendency of alveolar walls and small airways to stick together makking the lung more compliant
less force required to expand alveoli in lungs
allows you to breather more easily
*in humans Surfactant synthesis does not begin until late gestation
Lung compliance and elasticity:
What is lung elsticity?
The ability of the lung to return to resting volume after streched
Lung compliance and elasticity:
low elasticity?
lungs do not readily return to resting volume when respiratory muscles relax
must actively expire, no longer passive expiration
Lung Disease:
Fibrotic lung disease
Scarring of lung tissue
reduced lung compliance, inspiration difficult
shallow breathing
must breath more rapidly to obtain sufficient o2
Emphysema
smoking
lung is less elastic, damaged elastin fibers and alveoli
lungs more compliant but tend to collapse, inflammation
lung is easily inflated but expend more energy to expire
Asthma
chronic inflammatory disease of respiratory airway
bronchiospasm and constriction of airway
wheezing, coughing, shortness of breath
Airway resistance:
Airway diameter affects resistance to air flow
as diameter decrease resistance increase
higher resistance requires a large transpulmonary pressure gradient
parasympathetic nerve stimulation causes bronchoconstriction
sympathetic nerve stimulation causes bronchodilation
Dead space:
What is Tidal volume?
Volume of air moved in one ventilatory cycle
What is dead space?
Air does not participate in gas exchange
dead space
two components
Anatomical dead space:
colume of trachea and bronchi
alveolar dead space
volume of alveoli that are not perfused
What is inspiratory reserve volume (IRV)
volume of air inhaled over and above resting tidal volume
What is inspiratory capacity?
Tidal volume plus inspiratory volume
What is expiratory reseve volume?
Max air that can be forcibly exhaled above resting tdal volume
What is vital capacity?
max amount of air that can be moved in and out of lungs with one breath
Total lung capacity
Sum of vital capacity pluys residual volume which is the volume of air that remains in lungs even after maximal exhalation
