10: Respiratory system Flashcards
The function of the respiratory system
supply body with oxygen and to rid co2
Pulmonary ventilation
movement of air into and out of the lungs
external respiration
exchange of O2 and CO2 between air within the lings and blood
Transport of respiratory gases
via blood stream
Internal respiration
exchange of O2 and CO2 between blood and tissues (ISF)
Other integral roles of the respiratory system include;
- Speech/vocalisation
- Olfactory sense facilitation
- Control pH of body fluids via co2 removal
- Creation of pressure gradients that promote the flow of venous blood and lymph
- Help expel abdominopelvic urination, defecation and childbirth via breath holding.
Structure and function of the upper respiratory system
clean, humidify and warm incoming air, reabsorb heat and water from out going air.
Structure and function of the lower respiratory system
conducts air to the gas exchange surface (trachea and bronchi also help to clean, warm and humidify incoming air), gas exchange.
The function of the conducting zone
passageway that conducts, cleanses, humidifies and warms incoming air and reabsorb heat and water from outgoing air.
The function of the respiratory zone
where gaseous exchange occurs. Includes bronchioles, alveola ducts and alveoli.
Structures of the respiratory zone (upper respiratory system)
the nose or nostrils, nasal cavity, mouth, throat (pharynx), and voice box (larynx)
Structures of the conducting zone (lower respiratory system)
the passageway that conducts, cleanses, humidifies and warms incoming air and reabsorb heat and water from the outgoing air.
The nose summary
- only external structure
- beginning of the system
nostrils
nares
Nasal cavity contains
hair
mucosal epithelium lining
olfactory epithelium
sensory nerve endings- trigger sneeze to prevent irritants from getting to lungs
Mucosal epithelium purpose?
- around 1-1.5L/day is produced
- traps particles
humidified incoming air
contains antibacterial agents such as lysomes and definsins
Cilia structure and function
small hairs that move contaminated mucociliary to throat
mucociliary escalator
cilia and mucous
- moves contaiminated mucus up the throat-> stomach
protects respiratory zine from infection.
What stops cilia from working well?
age
cold temps (hence colds in winter)
damage from smoking (hence smokers cough)
nasal conchae structure and function
called a nasal turbinate or turbinal, is a long, narrow, curved shelf of bone that protrudes into the breathing passage of the nose in humans and various animals
- increases surface area of mucosal and creates turbulence so particles hit the walls and get stuck to the mucus.
Pharynx structure and function
aka the throat
- for both food and air
- shaped like a funnel that connects mouth to larynx
- Passageway for air (nasal cavity to larynx) and food (oral cavity to oesophagus)
- Contains lymphoid tissue (tonsils) which help to protect against pathogens
3 regions of the pharynx
1- nasopharynx (air only)
2- oraopharynx (dual)
3- laryngopharanyx (dual but begins to diverge)
Larynx structure and function
Structure= cartilage Function= - provide an open air wat to the trachea - separate food and air - facilitates voice production (holds vocal cords that are mucosal covered elastic fibers that vibrate when air rushes out of lungs to produce sound.) - includes the mucociliary escalator
Trachea structure and function
aka windpipe
connects the larynx to main bronchioles
structure= highly elastic, lined with ciliated mucociliary membrane, smooth muscle can constrict when we need to cough.
Function= mucociliary escalator, cartilage rings keep it from closing
approx 15-20 rings
Lungs and conducting zone structure and function
- Cone shaped
- elastic organs
- Apex= smallest tip. Lies deep to the clavicle
- Concave base= lies in superior to diaphragm
- Apex of heart lies to the left of the mid line
- Each lung is suspended in its own plural cavity, separated by plural membrane that compartmentalises the parts of the lung.
- Advantageous if one is infected/impacted the others can still able to function normally.
Parietal pleura structure and function
- Lines outside of lung separating it from thoracic wall.
- Continuous membrane that turns into visceral pleura when on lungs surface
Plural space structure and function
- Holds pleural fluid
- Acts at lubricant so that visceral and parietal and plural can slide along one another.
- Clings lungs to the thoracic wall
How many lobes are on each lung
Left: 2 (superior and inferior)
Right: 3 (superior, middle and inferior)
Lobes of the lungs structure
- Each lobe is functionally independent
- Each lobe is further divided into segments via connective tissue
- Each segment is served by;
o own artery
o own vein
o own airway (segmental bronchus)
Bronchi subdivisions
- divide into right and left primary bronchi
- branch up to 23 times to form bronchial tree of 2400km of airways
i. Primary bronchi
ii. Bronchi (that supply each lobe)
iii. Tertiary bronchi (divide repeatedly)
iv. Bronchioles= diameter <1mm
v. Terminal bronchioles= diameter <0.5mm
vi. Respiratory bronchioles= diameter <0.5mm
Respiratory zone
- where gas exchange occurs
Alveoli structure/components and function
Structure= thin-walled, expandable sacs
Function= site of gaseous exchange
Connected via pores
-
The function of alveoli pores
Pores= small holes that allow air pressure through lungs to be equalised + another rote for air to travel to other alveloi whos bronchi may have collapsed.
- similar to the artery circle in the brain, is helps avoid major damage and allows for function when injury occurs.
Alveoli macrophages
macrophages= provide as defense against any particles that manage to evade the cleansing processes of the upper respiratory ways
Two types of epithelial cells in the membrane
- Walls= made of type 1 epithelial cells for the respiratory membrane where they contact capillaries.
- Type 2 epithelial cells= scattered in alveoli and secrete fluid containing surfactant- detergent-like substance that coats alveoli surface, helping to keep them open.
Respiratory membrane structure and function
Function= Site of gas exchange via simple diffusion.
Structure= Thin air-blood barrier (0.5 nanometre wide)
- Thinness facilitates efficient gas exchange in conjunction with large surface area
- Respiratory membrane coated with fluid containing surfactant to;
o prevent delicate membrane from drying out
o acts to facilitate gas exchange.
Compose of
- single alveolar epithelial cell (types 1 cell)
- basement membrane
- Pulmonary capillary endothelial cell
Surfactant=
A fluid secreted by the cells of the alveoli (the tiny air sacs in the lungs) that serves to reduce the surface tension of pulmonary fluids; surfactant contributes to the elastic properties of pulmonary tissue, preventing the alveoli from collapsing.
2 ways blood is supplied to the lungs
- Pulmonary circulation
2. Bronchial circulation
Describe pulmonary ventilation
- Pulmonary arteries deliver deoxygenated blood to lungs
- Provide nutrients to alveoli (e.g. glucose)
pulmonary circulation: provides blood w/ nutrients to alveoli
Bronchial circulation
- Rise from aorta to provide oxygenated systemic blood to all lung tissue (except alveoli)
Bronchial circulation: all lung tissue except alveoli
3 types of lung innovation
- Visceral sensory fibres- monitor the conditions in the lungs
e. g. degree of stretch, presence of irritants-> inform brainstem (influence respiratory rhythm) - sympathetic fibres- dilate bronchioles via relaxing smooth muscles
- Parasympathetic fibres- construct the bronchioles by constricting smooth muscles making them smaller and allowing less air through the bronchioles.
- Changing bronchiole diameter alters resistance to air flow, thus regulating airflow.
Pulmonary ventilation definition and phases
breathing the concists of two phases
- Inspiration/inhalation: air flow into lungs
- Expiration/exhalation: air flows out of lungs
Pulmonary ventilation depends on
Breathing mechanical process that depends on volume and pressure changes in the thoracic cavity and lungs.
What is the relationship between pressure and volume
when pressure increases volume decreases (inverse)
- one goes up the other goes down.
Boyl’s law
Boyle’s law for a gas in a closed container, at a constant temp, the pressure is inversely proportional to the volume.
Define intrapleural pressure (suction)
the lungs adhere to the pleura so they are pulled during inspiration expanding the diagram and changing pressure.
Define Intrapulmonary pressure
the pressure inside the lungs
Define negative respiratory pressure
pressure in the region is lower than atmospheric pressure
Define positive respiratory pressure
pressure in the region is higher than atmospheric pressure
Define zero respiratory pressure
pressure is equal to atmospheric pressure
Recall the events of inspiration
- Inspiratory muscles (diaphragm + intercostal muscles) contract (diaphragm descends; rib cage rises)
- Increase thoracic cavity volume
- Lungs stretch and interpulmonary pressure increases.
- Interpulmonary pressure decreases.
Pressure in atmosphere is higher so the air flows in aka down the pressure gradient.
Recall the events of exploration
1- inspiratory muscles relax (diaphragm rises; rib cage descends due to recoil of costal cartilage)
2- thoracic cavity volume decreases
3- lung elasticity recoil passively; intrapulmonary volume decreases
4- intrapulmonary pressure rises (to +1mmHg)
5- air (gases) flows out of the lungs down its pressure gradient until intrapulmonary pressure is 0.
Define passive expiration
- Involves muscle relaxation only, no contraction.
- Depends on the elastic recoil of lungs (why don’t the lungs recoil to collapse?)
Define forced expiration
- Internal intercostals -> contract further depress the ribcage.
- Occurs in physical activity or specific vocalisations
- Involves contraction of accessory muscles
- Various abdominal muscles, e.g. rectus abdominus-> pull down rib cage, increasing intra-abdominal pressure and push diaphragm further upwards.
- All of these are an attempt to increase pressure in lungs to force it out much faster.
What 2 forces act to collapse lungs
1- lungs natural recoil tendencies (elasticity). They always want to come back together
2. Surface tension of the alveolar fluid which tries to bind to one another.
What 3 factors stop lungs from collapsing
- Surfactant that sits between water molecules in alveoli which stops them from getting to close to each other which reduces surface tension of alveolar fluid.
- Pleural fluid has a adhesive force between parietal and visceral pleura that sticks the lungs to the inner wall of the thoracic cavity.
- Elasticity of the chest wall pulls the thorax outwards while the elastic recoil of the lungs creates an inward pull -> negative intrapleural pressure keeps the lungs adhered to the thoracic wall.
Negative intrapleural pressure
A kind of vacuum like effect to keep lungs attached to thoracic wall. This means wherever the thoracic wall goes the lungs will go.
- it would take too much energy to inhale of the lungs collapse down to their smallest size.
What are the 3 main factors affecting ventilation
- resistance
- compliance
- Alveolar structure
- any changes in these can lead to disease and disorders
Define resistance
= opposition to gas flow
Gas flow= Pressure/resistance (same as blood flow)
caused by friction
between air and the airway walls (how much of airway gas is hitting the walls)
- Dependent upon airway diameter (>diameter = bronchodilation -> decreases resistance -> increases gas flow/ventilation
- Parasympathetic stimulation -> bronchoconstriction -> increases resistance -> decreases gas
Define compliance
= measure of the ability of the lungs and thoracic cavity to expand/stretch and thus enable inhalation.
Depends on:
1) Lung elasticity
2) Alveolar surface tension (surfactant production- if this isn’t produced alveoli will collapse)
3) Flexibility of muscles and joints of the thoracic wall (decrease with age)
A decrease in compliance leads to restrictive disorders
Define alveolar surface tension
=Surface tension between water molecule in alveolar fluid
- Tries to reduce alveoli to smallest possible size
- Makes alveolar expansion during inspiration more difficult
Surfactant plays a major role in this.
Surfactant structure and function
- Lipid-protein complex
- Reduces surface tension of alveolar fluid which;
o Prevents alveolar collapse
o Reduces effort required to expand alveoli -> facilitates ventilation
Define spirometry
- Measure’s volume and speed of air exchange (pulmonary ventilation)
- Pulmonary gas flow or ventilation can be measured using spirometer, graphed and analysed -> diagnose respiratory disorders
Define Tidal volume
amount of air inhales or exhaled during quite breathing
- Aprox. 500ml
Define Inspiratory reserve
tidal volume + what we can breathe in.
Define expiratory reserve respiration
what can forcibly be pushed out of lungs.
Define residual volume
volume of air remaining in the lungs after maximum forceful expiration
define vital capacity
- 3100-4800 ml
max amount of air we can exchange with atmosphere
- Alterations in VC can be used in the diagnosis of pulmonary disease/disorders
Total lung capacity
inspiratory reserve volume + tidal colume + expiratory reserve volume + residual volume= all of these together (6000ml in the average adult male)
OPD= obstructive pulmonary disorder
reduced airway diameter -> increased resistance (hard to get air into/out of the lungs) -> reduced air flow -> dyspnoea (difficulty breathing) -> hypoventilation (not breathing enough)
- takes longer to achieve vital capacity as it is harder to get in air.
OPD- Emphysema
Bronchioles collapse during exhalation, alveolar destruction
OPD- Bronchitis
irritants -> mucus accumulation in lower air ways -> inflammation and fibrosis -> obstructs airway
OPD- asthma
allergic) inflammation within airways-> bronchoconstriction
RPD- Restrictive pulmonary disorder cause
Cause= Decreased compliance (stretch) of lungs or thoracic wall -> inability to change thoracic/lung volume and thus draw in air
- Effect on VC= reduced
e. g. fibrosis, arthritis, paralysis
RPD= feels like they cant breath and have a rope tied around them under their arm pits.
Partial pressure
the concentration of each gas. Expressed in mmHg
4 factors affecting pulmonary gas exchange
1- partial pressure
2- solubility (of gas in alveola fluid)
3- Matching of alveolar ventilation (air flow) and pulmonary blood perfusion (blood flow)
4- structural characteristics of respiratory membrane
External respiration
in alveoli
- Gases diffuse down the partial pressure gradient:
o O2 from alveoli -> pulmonary capillaries
o CO2 from pulmonary capillaries -> alveoli - Equal amounts of CO2 and O2 cross the respiratory membrane (even though gradient for CO2 is small) because CO2 is 20x more soluble.
Internal respiration
in tissues
- O2 moves from the blood-> tissue due to large differences in partial pressure
- CO2 moves from tissues-> plasma
- Equal amounts of CO2 and O2 are exchanged
Coupling
Refers to the body’s response to increased ventilation or perfusion.
e.g. more blood flow to the alveoli, increased ventilation and vice versa.
this is controlled by the partial pressure of the blood. Partial pressure in the blood in controlled by localised events such as changing in arteriole diameter.
Perfusion
amount. ofblood flow to the alveoli
ventilation
amount of gas reaching the alveoli
Structure and function of the respiratory membrane
- very thin
- large surface area
- contains alveoil fluid + surfactant to prevent collapse and facilitate expansion and to facilitate gas exchange
Oxygen is transported on what? and why?
Hemoglobin in RBC’s
- they have a large SA:VOL
- stackable and felxable
- no membrane-bound organelles leaving 98% of volume to be used for O2 transport
Affinity
strength to which o2 bines to haemoglobin
Hypoxia
decreased oxygen at tissue level.
Presents with cyanosis= blue skin tone
Causes of hypoxia
o Anemia: too few RBC or decreased Hb
o Ischemia: blood circulation is reduced/blocked
o Hypoxemia: reduced PO2 in the blood (respiratory disease, decreased atmospheric O2)
o Historic hypoxia: cells are unable to use oxygen (poisons such as cyanide)
3 ways CO2 is transported to the lungs
10% dissolved in plasma
20% bound to HB (heamoblobin)
70% as bicarbonate ions in plasma (this is the equation)
Carbonic anhydrase
binds and breaks CO2 and H2 in hemoglobin to exchange them with the blood plasma.
Buffer
substance that resists changes in pH
- They can bind or release H+ ions to regulate
The most important blood ph Buffer is the carbonic acid-bicarbonate buffer system
e. g. if pH is to low buffer will bind H+ ions to being it back to neutral area
e. g. if pH is to high it will release H+ ions to being it closer to neutral
Where can the carbonic acid-bicarbonate buffer system reaction occur?
- This reaction occurs;
o Inside RBC as a part of CO2 transport (Learning objective 4)
o In the plasma (slowly as no enzyme present)as a buffer to control pH
Hypo ventilations effect on pH
- Hypo ventilating= slow, shallow breaths or holding breath
o Increases CO2 in blood stream (tipping balance)
o This causes increase in free H+ ions thus changing pH to a lower number
o Decease in pH= respiratory acidosis
Hyperventilations effect on blood pH
- Hyper ventilating= fast, deep o Blowing out to much CO2 o Decrasing CO2 in the body o Decrease H+ thus increasing pH o Increased pH= respiratory alkalosis
What are respiratoey centres and where re they located
receive information that tell them what the levels of CO2 and O2 are in the body
- They set a respiratory rhythm (both rate and depth) by controlling diaphragm and intercostal muscles
- Respiratory centres are sensitive to both excitatory and inhibitory stimuli
location= Pons and medulla oblongata
Ponds= regulation medulla oblongata= take a breath
Factors rate anmd depth of breathing that are picked up by respiratory centres for innovation
- CO2, H+ and (to a lesser extent) O2- via chemoreceptors
- Stretch/inflammation of the lungs- via stretch receptors
- Emotions (e.g. angry, frightened, excited)- via limbic system and the hypothalamus
- Choice (voluntary control)- controlled by the primary motor cortex
What do chemo receptors do? where are they found?
- Chemoreceptors detect changes in CO2, H+ and O2-> information sent to the respiratory centres
Central chemoreceptors
- Location= bain stem
- Function= detect CO2 changes
Peripheral chemoreceptors
- Location= aortic arch and carotid sinuses (bodies)
- Function= detect changes in pH, CO2 and O2
Chemoreceptors detect the levels of CO2, H+ ions and O2 in the blood stream. These are regulated variables whose levels need to be maintained within strict limits. Therefore if the brain recieves a message that the levels of any of these 3 factors is outside of the ranges of normal, it will send a message to the inspiratory muscles to change the rate of breathing in order to bring that variable back to within normal limits.
Reflexes that protect delicate lung tissue -
Explain the= Pulmonary irritant reflexes
irritants promote reflective constriction of air passages, reduce rate and depth of breathing (to prevent damage of respiratory zone)
o E.g. accumulated mucus, dust, noxious fumes
o Stimulate a cough when present in the larynx or trachea and sneeze when present in nasal
Reflexes that protect delicate lung tissue -
Explain the= - Inflation/stretch reflexes
stretch receptors in the lungs/airways are stimulated by lung inflation
o Upon inspiration, stretch receptors send inhibitory signals to the respiratory centre to end inspiration and allow expiration (prevents over stretching)
Hypoxia
reduced oxygen in the body
Anaemia
no/low haemoglobin
Ischemia
Blood circulation is reduced or blocked
Hypoxemia
low blood oxygen
