Flashcards in Block 2 W1&2 Deck (181):
What is internal respiration?
Tissue respiration - metabolic process in which oxygen is released to tissues or living cells and carbon dioxide is absorbed by the blood. Inside cell - oxygen is used to make ATP.
Transfer of gas between blood and cells.
What is external respiration?
Breathing - inhaling O2 from air to lungs and expelling CO2 from lungs to air.
Transfer of gas between respiratory organs and outer environment.
Describe the cough reflex (6 steps).
1. Diaphragm (innervated by phrenic nerve) and external intercostal muscles (innervated by segmental intercostal nerves) contract, creating negative pressure around lungs.
2. Air rushes into lungs to equalise the pressure.
3. The glottis closes and vocal cords contract to shut off larynx.
4. Abdominal muscles contract to increase air pressure in the lungs.
5. Vocal cords relax and glottis open -> releasing air at over 100mph.
6. Bronchi and trachealis collapse to form slits through which air is forced -> clears out any irritants attached to respiratory lining.
What are the 3 central control mechanisms of respiration?
Central neural rhythm
Central neural rhythm - where and what are the two groups of the respiratory centres?
Rhythm generated in respiratory centres in medulla.
2 groups: Dorsal respiratory group (initiates inspiration) and ventral respiratory group (inspiration and expiration).
Where is respiratory rhythm modified?
Pons and cortex.
What are the respiratory motor output and their innervations?
Diaphragm - phrenic nerve (Inhalation) (C345 keep the diaphragm alive).
Internal intercostals (Exhalation).
What is the chemical control of breathing?
Sensing of PO2 and PCO2 is done by central and peripheral chemoreceptors in ventral medulla (central) + aortic arch + carotid artery (peripheral). Elicit respiratory rate changes.
What is the role of central chemoreceptors in breathing?
Monitor pH in CSF.
CO2 + H2O H+ + HCO3-
Increase in CO2 - decrease in pH.
Fall in pH -> central chemoreceptors stimulate respiratory centres to increase ventilatory rate -> reduced PCO2.
What is the role of peripheral chemoreceptors in breathing?
Monitor PO2, pH and PCO2 in blood of carotid artery.
Fire more frequently when low PO2 and pH and high PCO2.
Firing rate increases as PO2 decreases below 100mmHg.
What is the link between diabetic ketoacidosis and hyperventilating.
Diabetic ketoacidosis -> hyperventilate as low pH sensed by carotid bodies.
What is hypoxic drive?
In type 2 respiratory failure (CO2 retained), pH drive to breath is replaced by hypoxic drive - body uses O2 instead of CO2 to regulate respiration.
What is the role of hormones in breathing?
Adrenaline (fight/flight hormone) increases ventilation.
How does sensory input control breathing?
Peripheral mechanoreceptors in joints sense speed of movement -> elicits brain to increase ventilation to compensate during exercise.
What is the Herring-Breuer reflex?
Lung stretching -> inhibit inspiration.
What is partial pressure?
A measure of the concentration of a gas in a mixture of gases.
What are the effects of opiates on respiration?
- Opiates inhibits the respiratory centres in the medulla.
- Reduce cough by acting as respiratory depressant.
- Reduce sensitivity to CO2 in medulla.
What are the 3 different body cavities?
What is present in the cranial end?
Will form the heart.
Where does the mouth form?
What is present in the caudal end?
Cloacal membrane - precursor of GIT and urinary tract opening.
What happens to cardiogenic mesoderm at 22 days?
Cranial and caudal ends rotate around and fold towards the centre of developing torso, constricting the yolk sac in the middle.
Forms the beginnings of gut tube - lined with endoderm.
Folding -> foregut + midgut + hindgut.
How does the umbilical cord develop?
At 28 days, the yolk sac begins to degenerate due to ectoderm tissues closing in laterally, anteriorly and posteriorly -> forms the umbilical cord.
What is the septum transversum?
Precursor of diaphragm, which separates the thoracic and abdominal cavities.
Describe the migration of the septum transversum.
22 days - specialised mesoderm is dragged along with heart as it rotates towards the centre.
26 days - septum transversum is between base of heart and stalk of yolk sac.
28 days - further rotation -> septum transversum is at inferior surface of heart.
What happens to the extra-embryonic coelom?
Closing of the yolk sac causes formation of space surrounding gut tube = coelom (cavity).
Septum transversum divides coelom into:
- Pericardial cavity
- Peritoneal cavity.
What are the pericardioperitoneal canals?
Septum transversum doesn't completely separate the thoracic and abdominal since there are openings in the back on either side of the foregut = pericardioperitoneal canals.
They connect the pericardial and peritoneal cavities.
How do lungs begin to develop?
25 days - lungs evaginates from ventral gut wall above the septum transversum.
28 days - protrusion buds into two -> primary bronchial buds.
30 days - secondary bronchial buds.
38 days - tertiary bronchial buds.
What grows from the lateral thoracic wall and when?
42 days - the pleuropericardial fold.
What can be found within the pleuropericardial fold?
- Common cardinal vein
- Phrenic nerve
What happens to the pleuropericardial fold?
They continue to grow medially until they meet and zip up.
The lungs expand laterally and ventrally.
The pleuropericardial fold separates the pericardium and pleural cavity.
Describe the pleura.
As the lungs expand, they grow underneath the mesothelial lining covering it entirely.
- Pleura membrane is a continuous layer.
- Visceral pleura lines lung.
- Parietal pleura lungs pleural cavity wall.
What is the functional significance of the pleural space?
For low friction movement.
How does the diaphragm develop?
- Pericardioperitoneal canals close off towards the septum transversum.
- pleuroperitoneal membrane zips towards the septum transversum.
- Muscle tissues (precursor myoblasts) migrate from lateral body wall into precursor diaphragm.
From what embryonic structures does the diaphragm derive from?
Dorsal mesentery of oesophagus
Mesoderm of body wall.
How is the innervation of the diaphragm related to its embryological origin?
- Initially, septum transversum is at level of 3rd, 4th, 5th cervical somites.
- Migrating myoblasts bring nerve supply from C3, C4 and C5.
- Definitive diaphragm descends into inferior thorax, cervical innervation is maintained.
What is eventration of the diaphragm and how does it occur?
The pericardioperitoneal canal fails to close so gut grows into thoracic cavity -> causes congenital diaphragmatic herniation.
This causes lung compression and hypoplasia.
What is parasternal hernia and how does it occur?
Lack of muscular tissue from body wall -> floppy diaphragm so gut grows into thorax.
Why does oesophageal hernia occur?
Due to congenital shortness of oesophagus.
Describe the tracheobronchial tree.
Trachea -> left primary bronchus -> secondary bronchus -> tertiary bronchus -> bronchioles -> terminal bronchioles -> respiratory bronchioles -> alveolar sac.
What is the level of bronchial bifurcation?
Angle of Louis - T4.
What is the difference between right and left main bronchi?
Right bronchi - wider, shorter and vertical. Gives off 3 lobar bronchi to 3 lobes. (easier to get foreign particles stuck).
Left bronchi - longer and horizontal. Gives off 2 lobar bronchi to 2 lobes.
What are bronchopulmonary segments?
Areas that are discrete anatomical and functional units and each are supplied with:
What are the 10 bronchopulmonary segments?
Right superior - apical + posterior + anterior segments.
Right middle - lateral + medial segments.
Right inferior - superior + anterior basal + medial basal + lateral basal + posterior basal.
Left superior - apical + posterior + superior + inferior.
Left inferior - anterior basal + medial basal + lateral basal + posterior basal.
Describe the structures of bronchioles.
Supported by smooth muscle.
Describe the histology of terminal bronchioles.
Ciliated cuboidal cells without glands.
What is visceral pleura?
Membrane that directly surrounds the lungs - simple squamous epithelium.
What is parietal pleura?
Membrane that lines the pulmonary cavity.
Where do the two pleura meet?
Hilum - where they are continuous. Visceral reflects and becomes parietal.
What are the costomediastinal and costodiaphragmatic recesses?
Spaces between visceral and costal pleura - lungs expand and retreat into these recesses during inspiration and expiration respectively.
What are the surfaces of the lungs?
- Costal surface - area in contact with ribs.
- Diaphragmatic surface
- Mediastinal surface
- Apex - above 1st rib, covered by cervical pleura.
What are the borders of the lungs?
- Anterior border - costal + mediastinal meet anteriorly.
- Posterior border - costal + mediastinal meet posteriorly.
- Inferior border - diaphragmatic surface.
- Cardiac notch - anterior border of left lung.
- Lingula - left superior lobe extends below cardiac notch.
What are the fissures and lobes of the lung?
Right lung -> superior + middle + inferior lobes.
- horizontal fissure separates superior and middle lobes.
- oblique fissure separates middle and inferior lobes.
Left lung -> superior + inferior lobes.
- oblique fissure separates superior and inferior lobes.
What does the scapula line?
Describe the relationship between the lungs and the ribs.
- 2nd & 4th rib -> sternal line anteriorly.
- 6th rib -> midclavicular line anteriorly.
- 8th rib -> mid-axillary line laterally.
- 10th rib -> mid-scapular line posteriorly.
What is the hila of the lungs?
Point of contact between lungs and outside.
What is the content of the hila?
1) 2 principle bronchi
2) Pulmonary arteries - left and right
3) Pulmonary veins - left and right superior and inferior
4) Bronchial arteries and veins
5) Pulmonary ligament
How are the lungs innverated?
Vagus nerve branches - anterior and posterior pulmonary plexus.
Describe the lymphatics of the lungs.
Describe the pulmonary arteries organisation.
Right anterior, left superior.
What level is thoracic place at and what does it do?
- Manubrio-sternal joint
- 2nd costal cartilage
- T4/T5 intervertebral disc
Separates superior and inferior mediastinum.
What are the contents of superior mediastinum?
- Aortic arch + 3 branches (brachiocephalic artery, left common artery & left subclavian artery).
- Brachiocephalic veins
Trachea + oesophagus + thoracic duct + vagus & phrenic nerve -> inferior mediastinum too.
How is inferior mediastinum organised?
- Anterior -> sternum - pericardium
- Middle -> pericardium
- Posterior -> pericardium - vertebrae.
What are the contents of anterior (inferior) mediastinum?
- Thymus gland/fibrofatty tissue
- Lymph nodes
- Sternopericardial ligaments
What are the contents of middle (inferior) mediastinum?
- Phrenic nerve
What are the contents of posterior (inferior) mediastinum?
- Thoracic duct
- Descending aorta
- Azygos vein
Describe the respiratory epithelium in nose, trachea and bronchus.
Pseudostratified columnar epithelium with 3 cell types:
- cilia -> mucociliary escalator
- goblet cells -> secrete mucus
- basal cells -> stem cells
Describe bronchiole epithelium.
Pseudo-stratified cuboidal epithelium with Clara cells replacing goblet cells.
Describe oropharynx and laryngopharynx epithelium.
Stratified squamous epithelium.
Subject to abrasive swallowing of food so change from respiratory epithelium.
What is lamina propria?
Loose connective tissue with blood vessels and nerves. Contain lymphocytes and are rigid components that keep airways open.
Describe respiratory bronchiole epithelium.
Simple cuboidal epithelium.
Describe alveoli epithelium.
Simple squamous epithelium - requires thin walls for minimal diffusion distance for gas exchange.
Describe olfactory epithelium.
Pseudo-stratified columnar epithelium made of olfactory cells - bipolar nerve cells. Contains non-motile olfactory cilia -> receptors for odour.
Describe the micro anatomy of trachea and primary bronchi (wall, sub-mucosa & mucosa).
Wall -> lumen kept open by 20 C-shaped hyaline cartilages anterolaterally.
Smooth muscle in gaps between cartilage - trachealis - posteriorly.
Sub-mucosa -> sero-mucus glands.
Mucosa -> pseudo-stratified ciliated columnar epithelium + lamina propria (connective tissue with elastin)
Describe the micro anatomy of the bronchi.
Tertiary bronchi -> less hyaline cartilage plates (don't completely encircle lumen) + more smooth muscle.
Goblet cells & bronchial arteries.
Describe the micro anatomy of the bronchioles.
Smooth muscle helical bands + no cartilage + un-ciliated.
Pseudo-stratified cuboidal epithelium + Clara cells (secrete some components of surfactant).
What is the features and function of mucociliary escalator?
Features: Mucus - gel phase over thin sol phase.
Semi-permeable barrier for nutrient exchange (H2O & gases).
Impermeable to pathogens.
Goblet cells + mucus glands.
Function: coordinated beating of cilia transports the particles towards oro-pharynx & nano-pharynx.
Escalator damaged by inflammation, smoking, pollution and infections.
What are the components of mucus?
- anti-proteases -> inhibits proteases released by bacteria.
- lysozyme -> anti-bacterial + anti-fungal
- lactoferrin + peroxidase + defensins
What are type I pneumocytes?
- Simple squamous alveolar cells
- Form the thin diffusion barrier for gas exchange.
What are type II pneumocytes?
- Simple cuboidal alveolar cells
- Produce surfactant.
What is the role of surfactant?
Reduces surface tension to prevent alveoli from collapsing.
- increase pulmonary compliance
- alveolar size regulation
- innate immunity -> contains SP-A & SP-D for opsonisation.
What is the respiratory membrane?
(layer of surfactant)
- alveolar epithelium
- alveolar basement membrane
- capillary basement membrane
- capillary endothelial membrane
What are the defence mechanisms of the respiratory tract?
- warming and humidification of air
- muco-ciliary escalator
- cough & sneeze
- secreted factors e.g. lysozyme & anti-proteases.
What are the immune defence mechanisms of the respiratory tract?
- leukocytes -> neutrophils, lymphocytes, D cells
- alveolar macrophages -> phagocytose particles
- mast cells
- inflammatory response
- Bronchus-associated lymphoid tissue (BALT)
What is minute volume?
volume of air entering and leaving the lungs each minute (pulmonary ventilation).
minute volume = respiratory rate x tidal volume
6000ml/min = 12/min x 500ml
What is tidal volume?
amount of air inhaled and exhaled during one normal breath
TV = dead space + volume of air entering alveoli
What is the normal respiratory rate?
New born - 30-60
young children - 20-30
adults - 12-20 breaths/min
What is compliance?
ability of the lungs and thorax to expand.
reduces the pressure difference needed to allow the lung to inflate
If alveolar ventilation is lower than pulmonary ventilation, how does this relate to dead spaces?
it is lower because there are anatomical and physiological dead spaces in the lungs
anatomical - volume of conducting airways (150ml)
physiological - non-perfused alveolus or areas don't participate in gas exchange
What is the equation for alveolar volume?
alveolar volume = RR x (TV - DS)
AV = 12 x (500 - 150)
AV = 4200ml/min
What is spirometry?
measure of ventilation
Define inspiratory reserve volume (IRV).
volume of extra gas that can be inhaled after normal inspiration by maximal inspiratory efforts
Define expiratory reserve volume (ERV).
volume of extra gas that can be exhaled after normal expiration by maximal expiratory efforts
Define residual volume (RV).
volume of gas that remains after maximal expiration
Define functional residual capacity (FRC).
volume of gas that remains after normal expiration
FRC = RV + ERV
Define inspiratory capacity (IC).
volume of gas that can be inhaled after normal expiration by maximal inspiratory efforts
IC = TV + IRV
Define vital capacity (VC).
maximum volume of gas that can be inhaled or exhaled in a respiratory cycle
VC = TV + IRV + ERV
Define total lung capacity (TLC).
total lung volume that the lung can hold
TLC = VC + RV
Since RV and FRC cannot be directly measured, how can they be measured indirectly?
When does increased RV occur?
emphysema, COPD and asthma
Define forced expiratory volume (FEV1).
volume of gas is expired in the first second of forced maximal expiration
Define forced vital capacity (FVC).
total volume of gas that can be forcibly expired after maximal inspiration
What does the FEV1:FVC tell us?
High - lungs are not compliant -> restrictive lung disease
Normal - 80%
Low - lungs are resistant -> obstructive lung disease
What is peak expiratory flow rate (PEFR)?
measures airway obstruction
peak flow rate decreases as lung volumes decrease as airway resistance increases
Obstructive diseases - PEFR reduces
Restrictive diseases - no change
What is the driving force of gas exchange?
Partial pressure difference of O2 and CO2.
What are the factors affecting rate of gas exchange?
- Partial pressure of the gas
- Solubility of gas in liquid (CO2 x20 than O2)
- Surface area available for gas exchange
- Membrane thickness of alveoli
Define diffusing capacity (DL).
Ability of gas to diffuse between alveolar air and blood.
High - exercise as more capillaries open and greater surface area.
Low - emphysema as reduced surface area.
How is oxygen carried in the body?
Dissolved in the blood
Bound to haemoglobin
Hb - tetramer 2a2b.
4 haem group (porphyrin ring + Fe2+) - each carry 1 O2.
Describe the reaction between Hb and O2.
Rapid and reversible
Without Hb, alveolar PO2 = arterial PO2 = no diffusion.
How is the O2-carrying capacity of Hb limited?
By the number of O2-binding sites on each Hb molecule.
What is the arterial oxygen content (CaO2)?
Amount of oxygen bound to Hb + amount of oxygen dissolved in arterial blood.
Describe the cooperative binding nature of Hb.
Binding of O2 to Hb is cooperative - binding of each O2 to Hb facilitates the binding of the next -> positive cooperatively (tetramers).
---> sigmoidal curve.
How can the Hb-O2 dissociation curve be described as?
Sigmoidal, which facilitates O2 loading in lungs and O2 unloading in tissues.
What are the factors affecting O2 binding to Hb?
- BPG (binds Hb and reduced its affinity to O2)
Shift to right - favours unloading in tissues.
Describe the foetal Hb-O2 dissociation curve.
Left shift -> higher O2 affinity at same PO2.
What happens at PO2 of 100, 40 and 25 mmHg?
100 - Hb is 100% saturated.
40 - Hb is 75% saturated.
25 - Hb is 50% saturated.
Describe O2 transport between lungs and tissues.
- Pulmonary capillaries - 100mmHg -> 100% Hb saturation.
- Peripheral tissues - low PO2 so low affinity -> unloading as reduced Hb saturation.
What is the Bohr effect?
Describes the effects of pH and CO2 on Hb-O2 dissociation curve.
How is CO2 transported in the body?
- HCO3- (70% -- 60%)
- Carbamino (23% --30%)
- Dissolved CO2 (7% -- 10%)
Define the Haldane effect.
Removing O2 from Hb increases the ability of Hb to pick up CO2 and H+.
CO2 dissociates more readily from oxygenated Hb.
How is HCO3- (carbonic acid) made?
CO2 + H2O H2CO3 H+ + HCO3-
Catalysed by carbonic anhydrase
Describe the transport of CO2 as HCO3-.
- CO2 generated in tissues.
- In RBC, CO2 combines with H2O to form HCO3-.
- HCO3- leaves RBC in exchange for Cl- (chloride shift) and is transported to lungs via plasma.
- In lungs, reverse reactions occurs so that CO2 is expired.
What does hyperventilation cause?
Low CO2 and alkalosis.
What does hypoventilation cause?
High CO2 and acidosis.
Describe how blood pH is maintained by ventilation?
Low pH (high H+) sensed by central chemoreceptors -> stimulates increased breathing to expel more CO2 -> less H+ free in blood.
How is blood pH maintained?
- Buffering by chemicals i.e. HCO3- and Hb
- Changes in ventilation
- Changes in renal excretion of H+ and HCO3-
What happens in respiratory acidosis?
Lungs retain CO2 (high HCO3- & pH falls)
What happens in respiratory alkalosis?
Lungs lose excess CO2 (HCO3- falls and pH rises)
What happens in chronic hypoventilation?
If hypoventilation becomes chronic, as in patients with chronic obstructive pulmonary disease (COPD), chemoreceptors lose their sensitivity and respond to increases in carbon dioxide levels inadequately.
When central chemoreceptors fail, peripheral chemoreceptors attempt to regulate respiratory function and restore acid-base balance. Peripheral chemoreceptors are sensitive to the amount of oxygen in peripheral blood.
Therefore, the patient's stimulus to breathe is no longer an increase in carbon dioxide levels, but from a low oxygen level sensed by peripheral chemoreceptors.
If the blood oxygen level is increased significantly by giving supplemental oxygen, the peripheral chemoreceptors will not stimulate breathing, resulting in apnea.
This alteration in physiologic function is the reason that patients with COPD are given supplemental oxygen at very low levels.
What is COPD?
Emphysema and chronic bronchitis are often clinically grouped together and referred to as chronic obstructive pulmonary disease (COPD), since the majority of patients have features of both, almost certainly because they share a major trigger - cigarette smoking.
What is chronic bronchitis?
A productive cough on most days of the week for at least 3 months' total duration in 2 successive years.
It becomes chronic obstructive bronchitis if spirometric evidence of airflow obstruction develops.
What is emphysema?
The destruction of lung parenchyma (alveoli, alveolar duct and respiratory bronchioles) leading to the loss of elastic recoil and loss of alveolar septa (wall) and radial airway traction, which increases the tendency for airway collapse.
Lung hyperinflation, airflow limitation and air trapping follow.
What are the external nose features?
Bone + cartilage covered by facial muscle and skin.
2 apertures (nares)
What are the internal nose features?
Anterior - nares
Posterior - nasopharynx via posterior apertures (choanae)
Describe the nasal septum.
Divides the nasal cavity into 2.
- perpendicular plate of ethmoid
- septal cartilage
Describe the respiratory mucosa.
Pseudostratified ciliated columnar epithelium + goblet cells.
Function - trap and humidify air.
Describe the olfactory mucosa.
At roof of nasal cavity.
Sensory receptors for smell.
Define conchae (turbinates).
3 bony shelves that project medially from the lateral walls of the nasal cavity (inferior, middle and superior).
Function - cleanses and increases SA.
Define nasal meatuses.
Broad opening inferior to each 3 conchae (inferior, middle and superior).
What does the sphenoid-ethmoidal recess have an opening for?
Spheno-ethmoidal recess is superior to superior conchae.
What does the superior nasal meatus have an opening for?
Posterior ethmoidal sinus
What does the middle nasal meatus have an opening for?
Anterior and middle ethmoidal sinus + frontal sinus + maxillary sinus.
What does the inferior nasal meatus have an opening for?
Define paranasal sinuses and list them.
Air filled bony cavities that surround the bone.
2. ethmoidal cells
What are the functions of the paranasal sinuses?
- resonation as hollow
- lined with respiratory epithelium so produce mucus that are drained into nasal cavity
- allow skull to be lighter.
Describe the blood supply to the nose.
Roof, anterior and lateral walls -> anterior and posterior ethmoidal branches of ophthalmic branch.
Meati, conchae and septum -> greater palatine + sphenopalatine + superior labial arteries.
Submucosal venous plexus - sphenopalatine + facial + ophthalmic veins.
Describe the Kiesselbach area/Little's area.
Area rich in anastomosing arteries
Describe the innervation of the nose.
Postero-inferior -> maxillary nerve
Antero-superior -> ophthalmic nerve
Common due to rich blood supply to nasal mucosa.
Bleeding arises from Little's area.
Nose picking -> rupture.
Inflammation and swelling of the paranasal sinuses mucosa.
Due to the paranasal sinuses being continuous with nasal cavity through apertures.
Infection spreads from nasal cavity.
Pansinusitis -> several sinuses inflamed and blocked.
Describe the pharynx
Muscular tube, extends from cranial base to inferior border of cricoid cartilage, C6.
Function - pathway for food and air to oesophagus and trachea.
What are the 3 circular muscles of the pharynx?
- superior (mandible)
- middle (hyoid)
- inferior pharyngeal constrictor muscles (cricoid)
Fan-like structures - all attach to pharyngeal raphe.
Function - constrict walls of pharynx during swallowing.
Describe the location and contents of nasopharynx.
Extends from cranial base -> uvula and soft palate/
- pharyngeal tonsils (adenoids) at roof of nasopharynx
- Eustachian tube -> drains and equalises pressure to optimise hearing.
Define otitis media.
Infection blocks Eustachian tube.
More prevalent in infants as the tube is more horizontally oriented.
Describe the location and contents of oropharynx.
Extends from soft palate -> epiglottis.
Function - receives bolus during deglutition, involuntarily contracts for food to enter oesophagus.
- palatine tonsils (between palatoglossal and palatopharyngeal arches)
- lingual tonsils (posterior to tongue)
Describe the location and contents of laryngopharynx.
Extends from epiglottis -> cricoid cartilage (C4-6).
The posterior and lateral walls - middle + inferior constrictor muscles.
Internal walls - palatopharyngeus + stylopharyngess muscles.
Contents - laryngeal inlet -> communication between laryngopharynx and larynx.
Describe the vasculature and innervation of the pharynx.
Vasculature - external carotid + superior thyroid arteries.
Pharyngeal venous plexus drains into internal jugular vein.
Innervation: sensory -
nasopharynx - maxillary nerve
oropharynx - glossopharyngeal nerve
laryngopharynx - vagus nerve
Motor - all -> vagus, except stylopharyngeus -> glossopharyngeal nerve.
Describe the larynx.
Tube that connects oropharynx with trachea (C3-C6)
- passage for air to lungs
- voice production
- protects trachea and bronchial tree during swallowing.
Composed of 9 cartilages bound together by ligaments and muscle. Contains vocal folds.
What are the unpaired and paired cartilages of the larynx?
Unpaired - thyroid, cricoid and epiglottis.
Paired - arytenoid, corniculate and cuneiform.
Describe the thyroid cartilage.
V-shaped, forms laryngeal prominence (Adam's apple).
Attached to hyoid bone by thyrohyoid membrane.
Describe the cricoid cartilage.
Only complete ring of cartilage in RS (signet ring shaped).
Attaches to thyroid cartilage by median cricothyroid ligament.
Attaches to 1st tracheal ring by cricotracheal ligament.
Describe the epiglottis.
Elastic flap of cartilage
Posterior to tongue and hyoid bone, anterior to laryngeal inlet.
Attaches to hyoid bone by hyo-epiglottic ligament.
Attaches to thyroid cartilage by thyroid-epiglottic ligament.
Attaches to arytenoid cartilage by ary-epiglottic folds - which form the opening of the larynx.
Describe the arytenoid cartilage.
3 sided pyramidal
Vocal process provides posterior attachment for vocal ligaments.
Sits superiorly on either side of cricoid.
Describe the corniculate and cuneiform cartilages.
Small nodules in ary-epiglottic fold.
What are the laryngeal cavities?
Laryngeal vestibule - between laryngeal inlet and vestibular folds.
Middle laryngeal cavity - air cavity between vestibular and vocal folds.
Laryngeal ventricle - recess between ventricular and vocal folds.
Infraglottic cavity - between vocal folds and cricoid cartilage.
Describe the vocal folds.
Formed by 2 different folds of mucosa to form a triangular-shaped membrane.
Superior vestibular fold = false vocal cords (protection)
Inferior vestibular fold = true vocal cords (vocalisation)
On either side of opening - rima glottidis.
How does vocalisation occur?
The vocal folds changes the shape and size of rima glottidis -> changes tension and vibrations causes phonation.
Describe the vasculature, innervation and lymphatics of the larynx.
- supraglottic -> superior laryngeal artery
- infraglottic -> inferior laryngeal artery
Superior and inferior laryngeal veins
Innervation (vagus): sensory -
- supraglottic -> superior laryngeal nerve
- infraglottic -> recurrent laryngeal
motor - all recurrent laryngeal except cricothyroid -> external laryngeal branch of superior laryngeal.
- supraglottic -> upper deep cervical lymph nodes
- infraglottic -> lower deep cervical lymph nodes.
Define hoarse voice.
Laryngitis - inflammation of vocal folds causes hoarseness/loss of voice by interfering with the contraction of vocal folds/causing swelling -> folds can't vibrate.
Inflammation of tonsils caused by infection.
Describe the trachea.
Anterior to oesophagus
Extends from inferior border of cricoid (C6) -> bifurcation of trachea (T4/5).
16-20 C-shaped cartilage rings + fibrous muscular bands (trachealis).
Describe the bifurcation of the trachea.
Trachea bifurcates and splits into two -> 2 primary bronchi.
Level of T4/5 - Angle of Louis and sternal angle.
Last tracheal ring - has 2 rings for each primary bronchus.
Differentiate between left and right bronchi.
Left bronchus - shorter and more horizontal
Right bronchus - longer and more vertical (easier to get things trapped).
What is the thoracic cage made of?
Sternum + 12 ribs
1-7 true ribs (articulate directly with sternum)
8-12 false ribs (articulate with sternum via costal cartilage of rib 7)
11 and 12th rib - floating ribs (no articulation).
What are the muscles of inspiration?
3. external intercostal
4. parasternal intercostal
What are the muscles of expiration?
1. internal intercostal
2. external abdominal oblique
3. internal abdominal oblique
4. Transversus abdominus
5. rectus abdominus
Describe the expansion of the thorax in respiration.
Transverse expansion (bucket handle) of thoracic cavity and anteroposterior expansion (pump handle) due to contraction of external intercostals mulches causes the lungs to expand by the elevation of ribs.
Describe the process of inspiration.
1. contraction of diaphragm and external intercostal muscles raise the ribs and increases size of thorax.
2. decrease in intrapleural pressure -> causes increase in lung volume.
3. lung expansion reduces alveolar pressure.
4. air moves down pressure gradient from atmosphere to lungs.