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what are the 2 major respiratory system processes?
Ventilation of the lung and gas exchange
What does the respiratory system work with to maintain homeostatsis?
What are the major functions of the respiratory system?
- gas excahnge,
- regulate blood pH
- produces vocal sounds
- excretes excess water and heat
- filters out impurities in air
- sense of smell
why do cells need oxygen?
to produce ATP, which is the energy needed for all metabolic activity
why is there CO2 in our system?
a byproduct from metabolic reactions.
why does CO2 need to be regulated?
CO2 plus H2O makes what?
Carbonic acid H2CO3 which can turn to bicarbonate ion HCO3 + H. So as CO2 increases, so does the H, so you become too acidic. We then breather faster to try to expel more CO2
What are the two functioning parts of respiratory system?
- Conducting portion (conducts air into lungs, filters, warms and moistens air) and:
- Respiratory portion where gas exchange occurs
what does the conducting portion consist of?
nose, pharynx, larynx,trachea, bronchi, bronchioles and terminal bronchioles
what does the repsiratory portion consist of?
tissues within the lungs where gas exhange occurs: respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.
What does inhalation and exhalation result from?
Presure changes coming from muscle relaxation and contraction
what are the 4 distinct processes of respiration?
- Pulmonary ventilation (breathing),
- external respiration
- internal respiration
what is pulmonary ventilation?
breathing, moving air in and out.
what is external respiration?
gas exchange between lungs and blood; blood in pulmonary capillaries gain O2 and lose CO2
explain respiration transport
transportation of oxygen and carbon dioxide between the lungs and tissues by the systemic blood vessels.
explain internal respiration
gas exchange between the systemic blood vessels and tissues. Blood in systemic capillaries loses O2 and gains CO2, while blood in tissue loses CO2 and gains O2.
What is celluar respiration?
when tissues lose CO2 and gain O2
What are the intercostal muscles?
2 sets of muscles between the ribs
what muscles are involved in inspiation?
external intercostal muscles
what muscles are involved in expiration?
internal intercostal muscles
what is the diaphragm?
dome shaped muscle between thoracic and abdominal cavities
what does the diaphragm do during inspiration?
flattens and increases the volume in the thoracic cavity. This increase in volume means a decrease in pressure so air rushes in
describe the steps of inspiration
inspiratory muscles contract (diaphragm descends, rib cage expands), thoracic cavity increases increasing volume and lowering intrapulmonary pressure, air flows down pressure gradient into lungs until pressure equal with outside pressure.
what happens during expiration
inspiratory muscles relax (diaphragm rises), thoracic cavity volume decreases which increases pressure so air flows down pressure gradient to the outside until intrapulmonary pressure is zero.
As alveoli pressure increases what does air do?
Describe tidal volume
the air we breathe in and out during normal respiration
what is inspiratory capacity volume?
is your maximum inhale, the most air you can inhale at a time.
explain expiratory reserve volume
Extra volume that can be maximally exhaled following normal tidal exhalation.
explain residual lung volume
this is the air that remains in your lungs after you have exhaled as much as you can
what is the functional residual capacity?
- all the air remaining in your lungs after a tidal exhalation.
- Sum of Residual Volume + Expiratory Reserve Volume
what is minute ventilation?
total volume of air inhaled and exhaled in one minute. Equals tidal ventilation x number of breathes per minute.
what is vital lung capacity?
is the most you can breathe in and breath out. So your inspiratory capacity (including tidal) and the expiratory reserve
describe total lung capacity
it is all the lung capacites, incl the residual capacity.
what does the p in pO2 or pCO2 mean?
It refers to the partial pressure in the lungs or blood stream
what does a spirometer measure?
lung volumes exchanged during breathing and rate of respiration.
What is atmospheric pressure?
It is the sum of all partial pressures in air. If atmospheric pressure is 760 then partial pressure for O2 is 21% x 760 (air is 21% oxygen)
what is parital pressure?
In a mix of gases, parital pressure is the pressure exerted by each gas in the mixture. If the partial pressure is higher, there is more gas. So 100mmHg contains more O2 than 40mmHg
which contains more oxygen, venous blood or alveoli?
more oxygen in alveoli (about 104 vs 40mmHg) which means O2 moves very quickly from alveoli to blood (about 0.25 seconds)
what is the purpose of external respiration or pulmonary gas exchange?
to oxygenate the deoxygenated blood
where does internal respiration/systemic gas exchange occur?
in tissues throughout the body. O2 diffuses from systemic capillaries into pheripheral tissue cells; CO2 diffuses in opposite direction.
what factors influence the rate of gas exchange? (4 things)
- surface area available
- partial pressure difference
- diffusion distance
- molecular wieght and solubility of gases
how is oxygen transported around body?
98.5% is attached to haemoglobin (this is the haeme part), and 1.5% is dissolved in plasma
How is CO2 transported around the body?
- 7% is dissolved in plasma
- 70% dissolved as bicarbonate ions
- 23% bound to haemoglobin (globin part)
During exercise is it easier or harder to release O2 from haemoglobin?
Explain the negative feedback regulation of blood pH by the respiratory system
Blood pH decreases (due to increase in H ions concentration); Chemoreceptors in medulla oblongata (central) and in aortic and carotid bodies (peripheral) detact change; send msg to inspiratory area in medulla oblongata; msg to effectors in diaphragm and internal intercostal muscles to increase respiratory rate and total volume so more CO2 expelled; less CO2 means fewer H ions so blood pH increases: homeostasis returned.
what is the anatomic dead space?
area in conducting airways containing air that doesn't undergo gas exchange
what controls our basic rhythm of breathing?
Medullary rhythmicity area within the medulla oblongata. It has 2 parts: inspiratory and expiratory areas.
what does the inspiratory area control?
during quiet breathing it controls the basic rhythm. Usually 2 secs inhalation (on) and 3 seconds exhalation (off).
what does expiratory area do?
helps with forced expiration
describe elastic recoil of lungs
natural tendency of thoracic walls and lungs to spring back once they have been stretched. Normal expiration requiries no muscle contraction, relies on elastic recoil.
what is the function of the nose?
- warms and moistens incoming air
- detects olfactory stimuli
- modifies speech
where does air enter the body?
usually through the external naris. These are 3 ridges inside the nasal cavity called conchae and they filters, warm and humidify incoming air.
what is the role of the epiglottis?
Manages food and air coming down laryngopharynx. Prevents food entering trachea, protects vocal cords and ventricular folds.
passageway for food and air, resonating chamber for speech and houses tonsils. Divided into nasopharynx, oropharynx and layngopharynx.
what is the function of tonsils?
Participates in immunological reactions against foreign invaders.
what is the larynx?
short passageway connecting larynogopharnx with trachea
what is the function of thyroid cartilage?
Adam's apple; forms anterior wall of larynx and gives it a triangular shape.
To do an emergency tracheotomy where would you cut?
Between cricoid and thyroid cartilage
what are the false vocal cords?
ventricular folds: superior pair that protects vocal folds
what are the true vocal cords?
inferior pair of vocal folds.
how is vocal sound made?
the vocal folds vibrate and produce sounds when stretched, narrowing the glottis.
what is the trachea more commonly known as?
Describe the bronchial tree
Trachea - primary bronchi - secondary bronchi - tertiary bronchi - bronchioles - terminal bronchioles
what are the strucural changes as you move down the bronchial tree?
Cartilage becomes less and finally none; smooth muscle increases as amount of cartilage decreases;
Describe the two structural
divisions of the respiratory system.
- Upper respiratory tract – nose, pharynx and associated structures.
- Lower respiratory tract – larynx, trachea, bronchi,
Describe the two functional
divisions of the respiratory system
- Conducting zone – interconnecting cavities and airways that moisten air and conduct it into the lungs- nose, pharynx, larynx, trachea,
- bronchi, bronchioles, terminal bronchioles.
- Respiratory zone – areas of
- the lung where gas exchange takes place (must have alveoli)-respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli.
Describe the pathway of air through the nose and
External nares, through superior, middle and inferior meatuses which are grooves between the superior, middle and inferior conchae of the nasal vestibule, internal naris. The nasal cavity is divided into left and right sides by the nasal septum.
List the 3 functions of the nose.
- 1. Warm, moisten filter air,
- (2) detect olfactory (smell) stimuli, (3) resonance of speech vibrations.
What structures increase the surface area of the nasal cavity to assist in filtering air
- superior, middle and inferior
What are the functions of
the paranasal sinuses
Production of mucus, resonating chambers for voice production, lightens bones of skull.
List the 3 anatomical regions of the pharynx.
Which are shared between the respiratory and gastrointestinal system?
Nasopharynx, Oropharynx, Laryngopharynx. Oro and laryngopharynx have shared respiratory and gastrointestinal function.
Which cartilages comprise the larynx?
Epiglottis, larynx, cricoid, arytenoid (x2)
Differentiate between ventricular and vocal folds
Vocal folds (true vocal cords) are involved in sound production; ventricular folds (false vocal cords) protect the vocal folds and close the glottis (space between vocal and ventricular folds) during straining to lift or defecate.
Which laryngeal cartilages move (due to laryngeal muscle contraction) to open and close the glottis in
What is the role of the epiglottis?
- To close off the glottis during swallowing to
- prevent food entering the larynx and trachea
Which gastrointestinal structure lies directly behind the C shaped cartilage rings of the trachea?
Where is the trachealis muscle found and what is
- Between the ends of the C shaped cartilage of the
- trachea; to allow expansion and contraction of trachea during inhalation/exhalation and allow food bolus to pass through esophagus (immediately posterior) more easily during swallowing.
What is the carina?
- Specialised last tracheal cartilage band that
- forms the bifurcation into left and right primary bronchi.
Describe the branching pattern of bronchi and
identify which structures each bronchi delivers air to.
- Primary (lung) to secondary (lobar) bronchi to tertiary
- (segmental) bronchi . Further branching but not specifically named.
What does a terminal bronchiole terminate?
The conducting zone
Describe the changes in respiratory epithelium from nasal cavity to alveoli
Generally decreses in thickness from columnar to cuboidal to squamous with progression to alveoli. Nasal cavity and nasopharynx=pseudostratified ciliated columnar epithelium; oro- and laryngopharynx = stratified squamous epithelium; larynx (below vocal folds), trachea and bronchi= pseudostratified ciliated columnar epithelium; larger bronchioles=ciliated simple columnar epithelium; terminal bronchioles= simple cuboidal epithelium; alveoli=simple squamous epithelium
Describe the changes in cartilage distribution
from trachea to bronchioles.
Cartilage decreases with progression through airways. Trachea & primary bronchi =C shaped/incomplete rings; smaller bronchi = plates of cartilage in wall; bronchioles=no cartilage in wall.
How many lobes are there in the left and right lung
Left = 2 lobes; Right=3 lobes
Describe the membranous layers that cover the
lung and line the thoracic cavity.
- Parietal pleura lines thoracic cavity; visceral pleura
- covers lung; pleural cavity between with serous fluid
Why does trauma to one lung not necessarily
affect the other lung?
Each lung is enclosed in a separate double layered pleural membrane and they are separated by mediastinum.
What is the role of pleural fluid?
- Reduce friction between membranes allowing
- them to slide easily during breathing.
Where are the base, apex and hilus of the lung located?
Base sits on diaphragm; apex is just above clavicle, hlius is found on medial surface (facing mediastinum) and is where primary bronchi enter lung and blood vessels enter and exit
Differentiate between a terminal bronchiole and
a respiratory bronchiole.
A terminal bronchiole terminates the conducting zone; a respiratory bronchiole has at least one alveoli in its wall and starts the respiratory zone.
What structure leads into an alveolar sac?
What 2 types of alveolar cells make up an
alveolus and what is the role of each?
Type 1 Alveolar cell=simple squamous epithelial cell that forms the alveolar wall; Type II alveolar cell= rounded epithelial cells that secrete alveolar fluid with surfactant.
What is surfactant and what is its role?
Surfactant is a mixture of phospholipids and lipoproteins which lowers surface tension of alveolar fluid and reduces the tendency for alveolar collapse.
Which muscle is primarily responsible for ventilation of the lung?
What is the first step in causing the volume and
pressure changes necessary for inhalation?
Contraction of the diaphragm (and external intercostal muscles).
Which accessory muscles assist the diaphragm during maximal inspiration?
- External intercostal muscles, sternocleidomastoid,
Which muscles are active in forced exhalation?
Internal intercostals, abdominals
Subatmospheric pressure in which space causes
the thorax and lung to move in tandem?
What is elastic recoil and what two forces contribute to it
- Elastic recoil is the natural tendency for elastic
- structures to spring back after being stretched. The surface tension of alveolar fluid and recoil of lung elastic fibres that where stretched during inhalation contribute to elastic recoil.
Define surface tension
inward force tending to collapse alveoli caused by polar water molecules that are attracted to each other
Define lung compliance
a measure of how easily the lungs can be stretched, pressure difference required to cause a change in volume.
Define airway resistance
resistance to flow caused by friction between air molecules and airway wall.
How does surface tension, lung compliance and airway resistance affect ventilation of the lung?
- surface tension –reduction of surface tension reduces effort required to inflate alveoli therefore ventilation increases for given level of effort.
- lung compliance- high compliance=less effort (pressure difference) required to ventilate lung; low compliance =(stiff lung), more effort required to ventilate lung.
- airway resistance- increased resistance (airway
- narrowing) requires more effort to maintain ventilation.
Explain Dalton’s law
Dalton’s law each gas in a gas mixture exerts its own pressure as if no other gases were present, ie. in proportion to the % of the total gas mixture it occupies.
Why does more CO2 stay dissolved in blood than
Because the solubility of CO2 is 24 times greater than that of oxygen.
What are the diffusion paths of oxygen and
carbon dioxide during external and internal respiration?
External respiration –O2 moves from alveolus to pulmonary capillary blood and CO2 from pulmonary capillary to alveolus
Internal respiration -O2 moves from systemic capillary blood to tissues and CO2 from tissues to systemic capillary blood
What causes oxygen to enter pulmonary
capillaries from alveolar air and to enter the tissue cells from systemic
The partial pressure difference for O2 , gas will move from a region of high partial pressure to a region of lower partial pressure.
How does partial pressure of atmospheric oxygen
change as altitude increases?
PO2 drops because atmospheric pressure drops with altitude, O2 still occupies 21% of air mix but total pressure is reduced.
What is the most important factor in determining
how much oxygen binds to haemoglobin?
The partial pressure of oxygen; the higher the PO2 the more O2 combines with Hb.
What relationship does the oxygen-haemoglobin
dissociation curve show?
The percentage saturation of haemoglobin at any specific PO2 level
What does the term affinity mean when describing the binding of haemoglobin to
Affinity describes ease or the ‘tightness’ with which Hb binds O2.
Describe 3 factors that influence the affinity of haemoglobin for oxygen.
As PCO2 increases and pH decreases the affinity of Hb for O2 declines. As temperature increases the affinity of Hb for O2 decreases.
These changes, increased temperature, more CO2 production and hence a decrease in pH, all occur during exercise. When you are exercising it is advantageous for the affinity of Hb for O2 to decrease so that more oxygen can be delivered to the exercising tissue. This is a useful way to remember the direction of change to Hb affinity.
Write the equation describing formation of hydrogen ion and bicarbonate from CO2 and H2O.
- CO2 + H2O
- H+ + HCO3-
Describe the location of the respiratory centre and the 3 areas that comprise it.
Pons and medulla- medullary rhythmicity centre in medulla oblongata, pneumotaxic area in pons, apneustic area in pons
Which nerves covey impulses from the respiratory centre to the diaphragm
How are the apneustic and pneumotaxic areas related to the control of respiration?
- Apneustic area –send stimulatory signals to the
- inspiratory area that cause long, deep inhalation.
- Pneumotaxic area – transmits inhibitory signals to
- inspiratory area to shorten inhalation and prevent lungs becoming too full of air
Where are the central and peripheral chemoreceptors located?
- Central =In or near medulla oblongata; peripheral=
- carotid and aortic bodies
What is the normal arterial PCO2?
What is hypercapnia?
Increased level of PCO2 above normal (40mmHg).
What happens to the rate and depth of breathing when the PCO2 is elevated?
Depth and frequency of breathing increase in negative feedback mechanism to reduce PCO2
How do proprioceptors affect respiration?
They increase rate and depth of breathing as soon as muscles start moving
What is the inflation reflex?
Stretch receptors in the bronchial/bronchiolar walls prevent overinflation of the lungs by inhibiting the inspiratory area
What is a normal range for pH in systemic arterial blood?
What 3 mechanisms allow removal of H+ from the blood?
Buffer systems, exhalation of CO2, excretion of H+ in urine
How do proteins and bicarbonate ions help maintain the pH of body fluids?
Protein- buffers both acids (H+ added to NH2 when H+ high) and bases (H+ released from COOH when H+ low), Hb buffers H+ when O2 has been released
Bicarbonate- HCO3- buffers H+ to form H2CO3 when H+ high, H+ released from H2CO3 when H+ is low
What is likely to happen to your blood pH if you hold your breath for 30 seconds?
Increase H+ so decreased pH
What are acidosis and alkalosis?
- Acidosis-condition in which blood pH is less than 7.35
- alkalosis-condition in which blood pH is greater than 7.45
What are the major physiological effects of acidosis and alkalosis?
- Acidosis- CNS depression via decreased synaptic
- transmission, disorientation, coma, death
Alkalosis- CNS and PNS overexcitability caused by increased synaptic transmission, causes muscle spasms, convulsions, death.
Which is a factor that does NOT affect haemoglobin's affinity for oxygen?