Compendium 4 Flashcards
For complete exchange of oxygen (O2)
and carbon dioxide (CO2) in respiration, four steps occur
simultaneously:
- Ventilation
- This is what most of us think of as breathing. It is the movements of the thorax and certain muscles that cause air to go into and out of our lungs.
- Movement of air in and out of lung - External respiration
- Oxygen enters the blood in the lungs and CO2 exits the blood in the lungs.
- Gas exchange between lungs and blood - Gas transport
- Carbon dioxide and O2 are circulated in the blood to and from tissues. - Internal respiration
- Gas exchange with the tissues involves the exit of O2 from blood to move into the tissues, while CO2 exits the tissues to enter the blood.
- Gas exchange between blood and tissues
Functions of the respiratory system
- Respiration
- Ventilation
- External respiration
- Transport of respiratory gases
- Internal respiration - Regulation of blood pH- can be altered by changing levels of blood CO2
- Voice production- air moving past the vocal folds makes sounds and speech possible
- Smell/ olfaction
- Protection- preventing microorganisms entering and removing it
- Production of chemical mediators- lungs produce ACE enzyme important for blood pressure regulation
7 structures make up respiratory system
- The external nose
- Nasal cavity
- Pharynx
- Larynx
- Trachea
- Bronchi
- Lungs
Classified in 2 ways
- Structurally
- Upper respiratory tract
External nose, nasal cavity, pharynx, larynx
- Lower respiratory tract
Trachea, bronchi, bronchioles, lungs - Functionally
- Conducting zone
Exclusively air movement
Nose to bronchioles
- Respiratory zone
Lungs, where gas exchange between air and blood takes place
The Nose
Consists of the external nose and nasal cavity
External nose:
- Visible structure
- Largest part is composed of hyaline cartilage plates
Nasal cavity
- The open chamber where air first enters
- Extends from anterior structures called nares (nostrils) to posterior structures, choana
Nares - External opening of the nasal cavity
- Just inside each naris, in the anterior part of the nasal cavity is the region called vestibule
Vestibule - Lined with stratified squamous epithelium
The choanae are the in the posterior part of the nasal cavity are the openings into the pharynx
Hard palate - Anterior portion of the roof of the mouth
- It is formed by the palatine process of the maxillae and the palatine bone
- Covered by a highly vascular mucous membrane that forms floor of nasal cavity
- Separates nasal cavity from oral cavity
Nasal septum - Divides nasal cavity into left and right portions
- Anterior part = cartilage
- Posterior part = vomer bone and the perpendicular plate of the ethmoid bone
Conchae - 3 lateral bony ridges on each side of the nasal cavity
- Used to be named turbinate bones – ‘wind turbine’ helping air churn through tunnels
- These tunnels are called meatus
- Superior, middle and inferior concha
- Superior, middles and inferior meatus
Functions of the nose
- Passageway for air
- Cleans the air
- Vestibule is lined with hairs which trap some of the large particles of dust
- Nasal septum and nasal conchae increase the surface area of the nasal cavity and make airflow more turbulent, increasing the likelihood that air will come into contact with mucus membranes (pseudostratified ciliated epithelium with goblet cells)
- Goblet cells secrete mucus which traps debris in the air
- Cilia on the surfaces of mucus membranes sweep the mucus posteriorly to the pharynx, where it is swallowed and eliminated by stomach acid - Humidifies and warms air
- Via warm blood flow through cavity
- Via moisture from mucus epithelium and excess tears which drain into nasal cavity - Smell
- Olfactory epithelium, the sensory organ for smell located in superior part of nasal cavity
Pharynx
- Receives air from the nasal cavity
- From superior to inferior, there are 3 regions of the pharynx = nasopharynx, oropharynx, laryngopharynx
Nasopharynx - Immediately posterior to nasal cavity
Specifically - posterior to choanae and superior to soft palate - Soft palate
Incomplete partition composed of muscle and cartilage – separates nasopharynx and oropharynx
Posterior extension of soft palate = uvula
Blocks swallowed materials away from the nasopharynx and nasal cavity - Nasopharynx is lined with mucus membrane which traps debris
- Pseudostratified ciliated columnar epithelium
- Houses openings of Eustachian tubes
- Posterior surface has pharyngeal tonsils
Oropharynx - Middle portion of the pharynx
- Immediately posterior to the mouth and begins at soft plate
- Region called fauces joins mouth and oropharynx
- Moist stratified squamous epithelium
- Palatine tonsils and lingual tonsils located near fauces
Laryngopharynx - Stratified squamous epithelium
- Posterior to epiglottis
Larynx
- Also know as voice box
- Passageway for air only
- Located in the anterior part of the laryngopharynx and extends from the base of the tongue to end of trachea
- Held in place by membranes and or muscles superior to hyoid bone
- Its rigidity is due to being made up of 9 cartilage pieces which are connected to each other by muscles and ligaments
- 6 paired (present on left and right side of larynx)
Arytenoid – seen by posterior aspect and medial not anterior
Corniculate – seen by posterior and medial
Cuneiform - 3 unpaired (single cartilage)
Thyroid – largest, also known as Adams apples
Cricoid
Epiglottis – prevents food going into trachea
Functions of the larynx
- Maintains an open passageway for air movement
- Thyroid and cricoid cartilage maintain this open passageway - Directs food into the oesophagus away from respiratory tract
- Epiglottis and vocal folds - Sound production via vocal folds
- Expired air moves passed vocal folds causing them to vibrate and produce sound - Trap debris from entering lungs
- Cilia on the pseudostratified ciliated columnar cells which line the larynx below the vocal folds
Trachea (windpipe)
- Descends from the larynx and sits anterior to oesophagus
- Has 15-20 ‘C-shaped’ hyaline cartilage rings -> support
- C-shape provides structural support to maintain open
- Dense connective tissue and smooth muscle in between cartilage rings
- Tracheal lumen (empty space) lined with pseudostratified ciliated columnar epithelium with goblet cells (mucous producing)
Tracheobronchial tree
- Carina is the last piece of cartilage of the trachea and is where it splits into 2 bronchi and is very sensitive so if any debris gets there you’ll have coughing fit
Moving from trachea to terminal bronchioles: - Increase in smooth muscle
- Decrease in cartilage
- Change in epithelium in lumen from pseudostratified ciliated columnar -> simple ciliated columnar -> simple ciliated cuboidal
Alveolus side
Simple squamous epithelium and the special name for this is called type 1 pneumocytes
- Type 1 pneumocyte
Gas exchange occurs here ->simple diffusion
- Type 2 pneumocytes (scattered in type 1 pneumocytes)
Cuboidal cell
Secretes a surfactant to reduce surface tension in the lungs and prevent collapse of the alveoli – so walls won’t stick together upon breathing out
Macrophages in the alveoli
Basement membrane
Capillary side
- Basement membrane
- Capillary endothelium
- Simple squamous epithelium
- Red blood cells
Lungs
- Cone shaped with a base and apex (top)
- Left lung has 2 lobes + cardiac notch where heart sits
- Right lung has 3 lobes
- Lobes separated by fissures- indentations of tissue
- Hilum on medial surface – entry point for blood and nervous supply, lymphatic vessels and bronchi
- Hilum – entry point for blood vessels, nerves and tracheal tree
- Bronchopulmonary segments
Theres 10 segments
Segment seprated by connective tissue septum and each segment receives own artery and vein from an individual tissue or segmental bronchus
Classify the structures into whether they fall within the ‘conducting zone’ or ‘respiratory zone’
Conducting zone: nasal cavity, pharynx, larynx, trachea, primary bronchus, secondary bronchus, tertiary bronchus, bronchiole, terminal bronchiole,
Respiratory zone: respiratory bronchiole, alveolar duct, alveolar sac, alveoli
Match the structure with its correct epithelium: vestibule, nasal cavity, nasopharynx, oropharynx, laryngopharynx, trachea, alveoli
Vestibule – stratified squamous epithelium
Nasal cavity – pseudostratified ciliated columnar epithelium
Nasopharynx - pseudostratified ciliated columnar epithelium
Oropharynx - stratified squamous epithelium
Laryngopharynx - stratified squamous epithelium
Trachea – pseudostratified ciliated columnar epithelium (with goblet cells)
Alveoli – simple squamous epithelium
Why do we breathe oxygen?
We breathe oxygen because it is a gas our bodies need to produce energy
Describe the path air takes as it move into and out of the lungs
Nose – nasal cavity – the pharynx – larynx – trachea – trachea splits into left and right bronchus – air continues through primary/ main bronchus – moves into secondary/ lobar bronchus – then into tertiary/ segmental bronchus – bronchioles – terminal bronchiole – respiratory bronchiole – alveoli
And same on the way out but in reverse
How does the respiratory tract protect the lungs from dust and pathogens?
Ciliated epithelium cam carry dust pathogens away from cells, out of body, away from lungs. Found in concha of nasal cavity, nasal pharynx, trachea, parts of the trachea bronchiole tree
Tonsils in nasopharynx and oropharynx which have immune protection
Mucus producing goblet cell scattered in epithelium that produce mucus, trap things cilia then move that mucus away from lungs
Hairs in vestibule of nasal cavity
Macrophages lining alveoli
Factors affecting gas exchange through the respiratory membrane
- Thickness of the respiratory membrane
- Thicker membrane reduces the rate of movement of gas
- Normal thickness is 0.5 to 1 micrometre, if thicker rate of exchange across respiratory membrane will be reduced (thicker due to fluid, Tb) - Surface area
- Lower surface area reduces volume of gas exchange taking place
- 300-500 million alveoli
- Emphysema – walls of alveoli break down reducing SA - Diffusion coefficient
- Diffusion coefficient – how easily a gas can diffuse in and out of a liquid or tissue
- A relative number
- Higher the diffusion coefficient = faster - Partial pressure - pressure exerted by each gas in a mixture of gases
- When the partial pressure (Pp) of a gas is greater on one side of the respiratory membrane compared to the other side, the gas moves from the side with the higher Pp to the side with the lower Pp
Gas transport
Oxygen (O2 ) - Transported via: Red blood cells (haemoglobin) (98.5%) most oxygen transported attached to a protein called haemoglobin Dissolved in blood plasma (1.5%) Carbon dioxide (CO2 ) - Transported as: HCO3 – dissolved as bicarbonate ions in plasma (70%) CO2 dissolved in plasma (7%) Bound to haemoglobin (23%)
How are O2 and CO2 exchanged in the alveoli
oxygen is breathed in by lungs, makes its way to alveoli and crosses the respiratory membrane, remembering most O2 travels attached to haemoglobin, so that oxygen moves from the alveoli across the respiratory membrane into the capillary and you’ve got your RBC here with haemoglobin protein, O2 binds to it, this blood then transported to different parts of the body through CS where O2 is transferred to various tissues for chemical reactions for energy production, and after reaction CO2 produced as by-product, leaves tissues and transported around body most dissolved in plasma as hydrogen carbonate, transferred from blood across respiratory membrane to be exhaled out of lungs
pulmonary ventilation
Process of moving air into and out of the lungs Some structures involved in ventilation: - Lungs - Diaphragm - Rib cage - Sternum - Intercostal muscles
inspiration
LUNGS: volume increases as it fill with air
DIAPHRAGM: moves inferiorly and flattens, contract
RIB CAGE: elevated moves upward
STERNUM: elevated moves upward with rib cage
INTERCOSTAL MUSCLES: contract
Expiration
LUNGS: volume decreases as air leaves DIAPHRAGM: moves superiorly as it relaxes into its dome-shape RIB CAGE: depresses move down STERNUM: depresses move down INTERCOSTAL MUSCLES: relax
Boyle’s law
volume is inversely proportional to pressure
the 2 pressures
Barometric air pressure (PB ) – atmospheric air pressure outside the body
Intra-alveolar pressure (Palv) – pressure inside the alveoli
End of expiration
Just blown all air out, the barometric pressure, so atmospheric pressure around you is equal to the intra-alveolar pressure
Pb = Palv
End of inspiration
Pb = Palv
During expiration
Volume of lungs decrease, pressure in lungs increases, diaphragm relaxes, rib-cage and sternum depress down
Palc > Pb
Changing alveolar volume
- Intrapleural pressure = pressure in the pleural cavity
- Forces which promote alveoli recoil:
Alveoli are covered in fine elastic fibers
Fluid which coats alveoli which is surfactant
——- Surfactant produced by pneumocyte - Forces which promotes lungs expansion:
Intrapleural pressure < intra alveolar pressure
——–Visceral pleura adhering to parietal pleura via pleural fluid, if other way around lungs would collapse
Why does expanding your thoracic cavity make you take a breath in?
Increasing volume in lung decreases pressure so atmospheric air goes from high to low into lungs
Why would your lungs collapse if you were stabbed in the chest?
If intrapleural pressure was lost, lungs would collapse like a balloon
How do O2 and CO2 pass between capillaries and tissue cells?
Simple diffusion from high to low concentration
Pulmonary volumes
Tidal volume – the amount of air inspired or expired with each breath, 500 mL healthy adult
Inspiratory reserve volume – the amount of air that can be inspired forcefully after inspiration of the tidal volume
Expiratory reserve volume – the amount of air that can be forcefully expired after expiration of the tidal volume
Residual volume – the volume of air still remaining in the respiratory passages and lungs after the most forceful expiration
Pulmonary capacities
The sum of two or more pulmonary volumes
Inspiratory capacity – the amount of air a person can inspire maximally after normal expiration (tidal volume + inspiratory reserve volume)
Functional residual capacity – the amount of air remaining in the lungs at the end of a normal expiration (expiratory reserve volume + residual volume)
Vital capacity – the maximum volume of air that can be expelled from the respiratory tract after a maximum inspiration (inspiratory reserve volume + tidal volume + expiratory reserve volume)
Total lung capacity – inspiratory reserve volume + expiratory reserve volume + tidal volume +residual volume
some definitions
Respiratory rate – number of breaths taken per minute
Minute ventilation – total amount of air moved into and out of the respiratory system each minute (tidal volume X respiratory rate)
- E.g. 500 ml X 12 breaths per minute = 6000 ml per minute
Anatomic dead space – space formed by nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles and terminal bronchioles. – the regions within the respiratory system where gas exchange is not taking place
Alveolar ventilation - volume of air available for gas exchange per minute
measuring lung function
Why?
- Diagnose and monitor diseases of the lungs
- e.g. asthma, chronic obstructive pulmonary diseases
How?
- Static versus dynamic (dynamic = time factor, static = no time factor)
- Using a spirometer – what we used in class
What?
- Lung volumes and capacities
Dynamic lung function
- Lung volume measurement in relation to time
- Vitalograph
Parameters measured: - Forced vital capacity (FVC) – maximal volume of air that can be forcefully expired as fast as possible after a deep breath in
- Forced expiratory volume in 1 second (FEV1 sec) – the volume of air expired in the first second of the test
- Forced expiratory volume 1% (FEV1%) – FEV1sec expressed as a percentage of the FVC- how much u breathe out in 1 sec, e.g. 72.3%
Obstructive lung disease:
- they can get all the air out of their lungs but the rate at which the air comes out might be slower than healthy person
Vitalograph
FVC: obstructive = normal
FEV1 sec: obstructive «< normal
FEV1%: obstructive «< normal
FEV1 sec is an indicator of an obstructed airway - E.g. Asthma, bronchitis, chronic obstructive pulmonary disorder (COPD)
Restrictive lung disease:
- Can’t get all of air out even though rate might be same as healthy person
vitalograph
FVC: restrictive «< normal
FEV1 sec: restrictive < normal
FEV1% : restrictive = normal
FVC is an indicator of a restricted airway - E.g. Emphysema
Exercise and ventilation
Ventilation increases abruptly - Onset of exercise - Movement of limbs has a strong influence Ventilation increases gradually Exercise adaptations - Slight increase in vital capacity - Slight decrease in residual volume - At maximal exercise, tidal volume and minute ventilation increases
Why do we breathe faster during and after exercise?
Muscles need more O2, lungs are the source
What information do dynamic tests of lung function give you?
Can tell you your lung function
- Vitalograph
