Respiratory Module 1 Part 2: Anatomy and Physiology PDF

Respiratory Module 1 part 2 Anatomy and Physiology Colleen Daniels MS, CRNA  Intrinsic muscles of the Larynx Control movement of the Vocal Cords T H E O W KN W IN G L L O ! FO ES ! !! S L ID ...

Respiratory Module 1 part 2 Anatomy and Physiology Colleen Daniels MS, CRNA  Intrinsic muscles of the Larynx Control movement of the Vocal Cords T H E O W KN W IN G L L O ! FO ES ! !! S L ID  Posterior Abducts cords (dilates the Cricoarytenoid cords) muscle Know Lateral (anteroir) Adducts cords function of Crycoarytenoid muscle positions cords so air following Transverse Crycoarytenoid passes through (closes muscle rima glottis) RLN Intrinsic Thyroarytenoid Relaxes cords (reduces Muscles muscle cord tension) shortens Cricothyroid Tenses cords (elongates muscle cords)  Posterior Cricoarytenoid Muscles Pull inferiorly and on the lateral angles of the arytenoids Causing the cords to pull apart ABDUCT Remember: Posterior Cricoarytenoids ABDUCT the Cords!! er i or t Pos apart l pul Lateral Cricoarytenoid Muscles Remember Lateral Cricoarytenoids ADDUCT Cords !!!! Opposes action of posterior cricoarytenoid muscles Pull laterally on the lateral angles of the arytenoids causing cords to move together ADDUCTION i sa L an ! c d! Ad Transverse Arytenoid Muscles Pull arytenoid cartilages together Position cords so they vibrate as air passes through during exhalation Generate sound and speech or singing  Thyroarytenoid muscles Lie IN the vocal cords lateral vocal ligaments Contraction pulls the arytenoids forward  this action loosens vocal cord ligaments Allows for lower frequency phonation  Cricothyroid muscle Located on anterior surface of the larynx Can swing the entire thyroid cartilage anteriorly Tenses the cords Changes frequency of phonation Remember CRICOTHYROID TENSES the cords  Nervous innervation Vagus Nerve (2 branches) Superior laryngeal nerve Arises from ganglion nodosum of vagus Divides into 2 branches Internal branch superior laryngeal nerve Provides sensation to laryngeal side of epiglottis to true cords (tongue side is innervated by glossopharyngeal) Internal branch also innervates interarytenoid muscle (phonation) External branch superior laryngeal nerve MOTOR Inferior constrictor muscle of the pharynx and to cricothyroid muscle Lengthen or increase tension of cords If paralyzed  weak rough voice easily fatigued Inferior laryngeal nerve (AKA Recurrent laryngeal nerve) Left descends with vagus and loops around the aorta and comes back up Right travels with vagus along subclavian artery loops around this artery and comes up Supplies sensation to larynx (except cricothyroid part) Nervous innervation  Nervous Innervation Motor innervation External branch of Superior Laryngeal nerve innervates Cricothyroid muscle (tenses cords) Recurrent Laryngeal Nerve is major motor nerve of larynx Sensory innervation Internal branch of Superior laryngeal nerve is major sensory nerve of Larynx Supplies laryngeal tissue from vocal cords ↑ Recurrent laryngeal nerve supplies sensory innervation to laryngeal mucosa inferior to cords  Laryngospasm Sensory  Internal branch of Superior Laryngeal Nerve (branch of vagus) Motor  External Branch of Superior laryngeal nerve (branch of vagus) Muscle involved  cricothyroid muscle tenses the cords Easy way to remember!! If the CRICOTHYROID muscle tenses the cords and causes a laryngospasm…………… You may need to do a CRICOTHYROTOMY  Clinical Application Damage to External branch SLN  Weakness, huskiness of voice. Cricothyroid muscle is paralyzed – cords cannot be tensed Unilateral Right RLN injury  Hoarseness as paralyzed cord assumes intermediate position Bilateral RLN Nerve damage  Each cord is paralyzed and assumes intermediate position Cords can flop together causing airway obstruction, aphonia. Rare. Emergency! Intubation!  Clinical Application Hoarseness after subtotal thyroidectomy can be caused by either Unilateral RLN injury SLN damage (rarely) Stridor following thyroidectomy caused by either Hypocalcemia (tetany) Bilateral RLN injury (floppy cords) Lower Airway  Tracheobronchial Tree After passing through larynx inspired air enters the tracheobronchial tree A series of branching airways referred to as “generations” or “orders” Consists of 23 divisions or generations*** Airways become progressively Narrower Shorter More numerous Tracheobronchial Tree  2 major forms of airways Cartilaginous airways Serve only to conduct air between external environment and sites of gas exchange Non-cartilaginous airways Serve as both conductors and as sites of gas exchange Which generation “by number” does gas exchange or respiration begin ? M&M  Histology Tracheobronchial tree composed of 3 layers Epithelial lining Lamina propria Cartilaginous layer Histology of the Tracheobronchial tree Tissue cell types A.Stratified squamous epithelium B.Pseudostratified columnar ciliated epithelium C.Simple cuboidal epithelium D.Simple squamous epithelium  Epithelial lining Primarily pseudostratified ciliated columnar epithelium (extends from trachea to bronchioles) 200 cilia per ciliated cell As bronchioles become smaller columnar become more cuboidal with less cilia (disappear) No cilia in respiratory bronchioles Mucous glands Separated by lamina propria by basement membrane Along basement membrane  basal cells (reserve cells) and mucous cells Brush cells  Mucous layer Covers epithelial layer of tracheobronchial tree 95% water 5% glycoprotiens, carbohydrates, lipids,DNA, cellular debris, foreign particles Mucus produced by Goblet cells Submucosal glands Innervated by vagal parasympathetic nerve fibers CN X Produce 100ml bronchial secretions per day Increased sympathetic activity decreases gland secretion Prominent in bronchioles  disappear in terminal bronchioles  Mucous blanket 2 distinct layers Sol layer Cilia move in wavelike motion in sol layer Propels mucus and foreign particles toward larynx Aka  mucociliary transport Gel layer More viscous Epithelial lining of Tracheobronchial tree  Factors that decrease mucociliary transport Cigarette smoke Dehydration Positive pressure ventilation Endotracheal suctioning High inspired O2 concentrations Hypoxia Atmospheric pollutants (sulfur dioxide, nitrogen dioxide, ozone) General anesthetics Parasympatholytics (atropine) Exposure to irritants (tobacco smoke)↑ #mucus producing goblet cells and ↓ #ciliated cells  ↑ volume Tracheal mucus flow is increased with COPD  Lamina propria Submucosal layer of tracheobronchial tree Loose fibrous tissue Contains tiny blood vessels Lymphatic vessels Branches of the vagus nerve 2 sets Smooth muscle fibers  wrap around tracheobronchial tree Outer portion of Lamina propria is surrounded by thin connective tissue layer  peribronchial sheath  Immune Response Humoral immune response occurs here. Involves circulating antibodies involved in allergic response such as allergic asthma Antibodies (Immunoglobulins) are serum globulins or proteins that defend against antigens (pollen/dander) Immunoglobulins IgG IgA IgM IgD IgE (reaginic) antibody basic to allergic response  IgE antibody antigen reaction Susceptible individual exposed to antigen Lymphoid tissue releases IgE antibodies Attach to surface receptors on Mast cells Estimated 100,000-500,000 IgE receptor sites per Mast cell Once IgE antibodies attach to Mast cell  individual is “sensitive” to specific antigen Each mast cell has 1000 secretory granules that contain chemical mediators Continued exposure or re-exposure to same antigen creates antigen- antibody reaction on surface of mast cell which works to destroy or inactivate the antigen This response causes mast cell to degranulate (break-down)  Mast Cell Releases Chemicals released from Mast cell during Antigen-Antibody-IgE response Histamine Heparin Slow Reacting Substance of Anaphylaxis SRS-A Platelet activating factor (PAF) Eosinophilic chemotactic factor of anaphylaxis (ECF-A) Chemical release from mast cells causes Increased vascular permeability Smooth muscle contraction (bronchial) Increased mucus secretion Vasodilation Edema Immunologic mechanisms  Allergic Asthmatic Attack Bronchial edema Bronchospasms Wheezing Increased mucus production Air trapping Lung Hyperinflation  Cartilagenous Layer Outermost layer Progressively diminishes in size Cartilage is absent in bronchioles < 1mm diameter  Cartlaginous Airways Conducting Airways Trachea Main Stem Bronchi Lobar Bronchi Segmental Bronchi  Trachea 11 – 13 cm long (10-12cm Barash) From incisors to carina  26cm 1.5 – 2.5 cm in diameter (20mm Barash) Extends from cricoid cartilage of larynx to about level of second costal cartilage or T4-T5 At level of carina trachea divides into right and left mainstem bronchi Trachea has 15 – 20 “C” shaped cartilage rings Cartilages are incomplete posteriorly Posteriorly  the trachea and esophagus share a fibroelastic membrane Tracheal epithelial layer pseudostratified columnar ciliated epithelium (damaged by exposure)  Trachea Blood supply  inferior thyroid artery (branch of subclavian artery) Incisors to carina  26cm Incisors to larynx  13cm Innervated by Vagus nerve Diameter approximates index finger Not a fixed structure (moves with head flexion or extension)  Trach vs Cricothyrotomy incisions Tracheostomy Cricothyrotomy  Main Stem Bronchi First generation Right Left Branches off 25° angle Branches off at 40-60° Wider angle More vertical M&M 45º 5cm shorter than left  Lobar Bronchi Lobar bronchi are the tracheobronchial tree’s second generation Left mainstem Right mainstem bronchi bronchi Left mainstem Right mainstem bronchi divides into bronchi divides into Upper Upper Lobar Bronchi Middle Lobar Bronchi Lower Lower Greater diameter than Leaves trachea at left angle ~ 45° Leaves trachea at an angle ~ 25° Aspiration or endobronchial intubation more likely C-shaped cartilages that support the trachea andhere mainstem bronchi progressively form cartilagenous plates around the  Right mainstem bronchus Leaves trachea at angle of 25° Aspiration or endobronchial intubation more likely to occur in Right Right upper lobe bronchus drives almost directly posterior at 90° angle Foreign bodies and aspirated material generally end up in Right upper lobe In children (