Lecture 10 - Respiratory System Anatomy

Breathing & Respiration

  • 3 processes required for respiration to occur

    1. Ventilation: Movement of air into/out of lungs

    2. External Respiration: Gas exchange between air in lungs & blood

      • Transport of oxygen & carbon dioxide in blood from outside

    3. Internal Respiration: Gas exchange between blood & tissues

Other Respiratory System Functions

  1. Regulation of blood pH: Altered by changing blood carbon dioxide levels

    • Bicarbonate System - buffers pH changes in blood

  2. Production of Chemical Mediators: ACE

    • Angiotensin Converting Enzyme - produced by lungs

    • Controls blood pressure

  3. Voice Production: Movement of air past vocal folds - makes sound & speech

    • movement of air past vocal folds produces sounds + movements of mouth & tongue + resonating chambers (nasal passages & sinuses)

  4. Olfaction: Smell occurs when airborne molecules are drawn into nasal cavity

  5. Protection: Against microorganisms by preventing entry & removing them from respiratory surfaces

    • Structures from nasal passageways → alveoli to remove microorganisms entering body/attempting

Respiratory System

  • Upper Respiratory System

    • Nose, Nasal Cavity

    • Pharynx (Throat)

    • Larynx (Voice box)

  • Lower Respiratory System

    • Trachea (Windpipe)

    • Bronchi (Branches of trachea → lungs)

    • Lungs

  • Conducting Zone:

    • Movement of air, no gas exchange

    • All structures leading up to alveoli

  • Respiratory Zone:

    • Gas exchange

    • Alveoli - only location of gas exchange

Nose/Nasal Cavity

  • Cartilage creates openings → Nares

    • Nares/Nostrils - Air enters nasal cavity

  • Nasal Vestibule - Stratified Squamous Epithelial Cells

    • Aligned w/ hairs

    • Traps large particles floating in air

    • First line of defence into respiratory system

    • Stratified Squamous → closest to external environment, greatest layers of protection

  • Hard Palate - Base of nasal cavity

    • Maxillary bones, maxilla, palatine bone

    • Separates nassal cavity from oral cavity

  • Nasal Conchae - Ridges that line the lateral sides of nasal cavity on right & left

    • Superior, middle, & inferior

    • createas turbulent airflow

    • Large surface area for mucous membranes

  • Mucous Membranes - Produce mucus, help trap smaller particles, highly vascular

    • Help heat air moving through passageway

    • Adds moisture to air

  • Nasal Meatus - Canals formed in between Nasal Conchae

    • Superior meatus between superior & middle conchae

    • Middle meatus between middle & inferior conchae

    • Inferior meatus below inferior conchae

    • Passageway where air moves from vestibule → back of nasal cavity

    • Creates surface area for contact with nucous membranes

  • Olfactory Epithelium - On superior region of nasal cavity

  • Sinuses - Structures in bones of nasal cavity

    • Small cavities w/in bone

    • Frontal Sinus - W/in frontal bone

    • Sphenoidal Sinus - Sinus in sphenoid bone

      • Both makes up → Paranasal Sinus

  • Paranasal Sinus - lined w/ mucous membranes

    • Secreats secretions into nasal cavity - layers of protection for air

    • helps w/ speech production

      • Resonate sounds

  • Choana (Choani) - opening, end of nasal cavity

    • Internal Nares (openings) → pharynx

  • Septum - Separates left & right side

  • Matrices - Where some mucous is drained into

  • Lacrimal Duct - Drains into inferior meatus

Functions of Nasal Structures:

  • Olfactory epithelium for smell

  • Pseudostratified Ciliated Columnar w/ goblet cells lines nasal cavity

    • wwarms air due to high vascularity

    • Mucous moistens air & traps dust

    • Cilia move mucous towards pharynx

  • Paranasal Sinuses - open into nasal cavity

    • lighten skull

    • resonate speech

Pharynx

  • Muscular Tube (13cm long)

    • Skeletal muscle & mucous membrane

  • Choanae → esophagus

  • Functions

    • Passageway for food and air

    • Resonating chamber for speech production

    • tonsil (lymphatic tissue) - immunological functions

  • 3 Main sextions

    • Nasopharynx

    • Oropharynx

    • Laryngopharynx

  • Choanae → esophagus

    • Esophagus starts same level as trachea

    • Esophagus → digestive system

    • Trachea → Respiratlry system

  • Nasopharynx - most superior portion of pharynx

    • Choanae → soft palate

    • Soft Palate - Muscle w/ mucous membrane

      • Continuation of hard palate at back of oral cavity

      • closes off nasal cavity when swallowing

    • Uvula - At very end of soft palate

      • closes off passageway - food/fluids dont move into nasal passage

    • Auditory Tube - Equalize air pressure in middle ear

    • Pharyngeal Tonsils - Adenoids

      • First tonsils

      • Mass of lymphatic tissue

      • Inflammed in response to cold

  • Oropharynx - Next region of pharynx

    • soft palate → epiglottis

    • Epiglottis - Closes off airway when swallowing

    • Back of oral cavity → pharynx

    • Where food & fluids are able to move from oral cavity into throat/pharynx

    • Fauces - Opening of oral cavity

    • Palatine Tonsils - More superior

    • Lingual Tonsils - More inferior

  • Laryngopharynx - Most inferior part of pharynx

    • Epiglottis → beginning of esophagus

    • Carries both food & fluid to esophagus + air to trachea

Pharynx: Epithelium

  1. Nasopharynx:

    • Posterior to choanae/superior to soft palate

    • Passage of air only

    • Lined with pseudostratified ciliated columnar epithelial cells

      • Just like nasal cavity

  2. Oropharynx:

    • Soft palate to epiglottis

    • Common passageway for air & food

    • Stratified squamous epithelial cells (protection)

      • Like nasal vestibule

  3. Laryngopharynx:

    • Epiglottis to esophagus

    • Common passage for air and food

    • stratified squamous epithelial cells (protection)

Larynx: Structure

  • Voice box - opening/passageway of air down to trachea

  • Larynx = pharynx → trachea

  • Thyroid Gland - wraps around trachea region

  • Made up of 9 pieces of cartilage

    • 3 unpaired

    • 6 paired

    • held together via ligaments & muscles

    • Many attach onto Hyoid Bone

  • Epiglottis - First unpaired piece of cartilage

    • flap of elastic cartilage

    • Flexible & movable

    • covers over larynx and opening of trachea when we swallow

    • slightly larger than opening - hangs over edge

    • Attached via ligaments to next piece of cartilage

  • Thyroid Cartilage - Aka adams apple, attached to epiglottis via cartilage

    • Unpaired cartilage

    • Changes during puberty in males

    • Create/maintain opening/passageway in larynx so air can continually enter into conducting tubes & trachea

  • Cricoid Cartilage - Unpaired cartilage, attached via ligaments

    • Ring of cartilage at base of larynx

    • Sits on top of rings that form trachea

    • Create/maintain opening/passageway in larynx so air can continually enter into conducting tubes & trachea

  • Pairs of ligaments covered by mucus membranes → creates folds

    • Vestibular Folds/False Vocal Cords - Most superior folds

    • Vocal Folds/True vocal cords - Most inferior folds

    • lined w/ stratified squamous epithelium

      • Changes in shape as they open and close → creates sound waves

Cartilages of Larynx

  • Tyroid Cartilage - Adams apple

  • Epiglottis - Leaf shapped piece of elastic cartilage

    • During swallowing, larynx moves upwards

    • Epiglottis bends to cover glottis

  • Cricoid Cartilage - Ring of cartilage attached to top of trachea

  • 3 additional pairs of cartilages

  • Bottom of Larynx

    • attachment onto trachea

    • Trachea made up of C shaped cartilage rings (open on posterior side)

  • Larynx = Structure above trachea

    • Epiglottis At the top

      • Attached onto thyroid cartilage via small ligaments

      • Helps to allow it to move during swallowing

    • Thyroid Cartilage - Adams apple

      • Bulk on anterior side, not much in posterior side

      • Attaches onto Hyoid Bone Via a membrane Thyrohyoid Membrane

    • Cricoid Cartilage - More prominant on posterior side

      • Forms complete ring at base of larynx ontop of trachea

    • Arytenoid Cartilage - First paired cartilage

      • Articulates with posterior superior cricoid cartilage

      • Attaches onto vestibular & vocal folds

      • Plays role in speech production

    • Corniculate Cartilage - Second paired cartilages

      • Small, on tips of arytenoid cartilage

    • Cuneiform Cartilage - Final paired cartilage

      • Embedded in mucous membrane anterior to corniculate cartilage

      • Supports lateral aspects of epiglottis & vocal cords

Vocal Folds

  • When vocal folds are open

    • Positon for breathing

  • When vocal folds are closed

    • Stops materials from entering trachea

    • Position for speaking

  • Arytenoid Cartilage - Attaches onto muscles to move them

    • Forms articulation with cricoid cartilage ring

    • Attaches to vocal folds (muscles)

    • Vocal folds attached to arytenoid cartilage on posterior side, and attached to thyroid cartilage on anterior side

    • Moves laterally & medially to change opening of vocal folds

  • Vestibular Folds - Ligaments (superior)

    • Create mucous membrane

    • Not involved in voice production (False vocal Cords)

  • Vocal Folds - Inferior to Vestibular folds

    • Covered in mucous membrane

    • Attached to arytenoid cartilages

      • Open (breathing)

      • Closed (speaking) or closing opening to trachea

  • Glottis - Space between vocal folds

    • Open glottis = braething

    • Close glottis - close airway (speech)

  • Abduction - Vocal folds are apart

    • Lateral rotation of arytenoid cartilages via small muscles

  • Producing sounds → bring vocal folds together

    • Forcing air through vocal folds creates areas of less compressed air & more compressed air (sound waves)

    • Changing pitch of sound waves

      • Move arytenoid cartilages arteriorly/posteriorly

        • Towards posterior side → greater tension → raise pitch

        • Towards anterior side → less tension → lower pitch

  • Adduction - Pulls arytenoid cartilages (and vocal folds) together

    • Causes medial rotation of arytenoid cartilages

Trachea Structure/Function

  • 12 cm long

  • extends from larynx → T5

  • 16-20 C-shaped rings of hyaline cartilage

    • Supports dense regular connective tissue & smooth muscle

  • Open portion of rings on posterior side - accommodates esophagus (posterior to trachea)

    • Other side of C made up of combination of elastic membranes & muscle known as Trachealis Muscle

    • C shape → prevents trachea from collapsing

  • Carina - At base of Trachea

    • Portion of cartilage w/ bifurcation

    • Allows initial branches of bronchi to move into right/left lungs

    • has membrane that’s very sensitive to irritation

      • Particle stimulates cough reflex

  • Trachealis Muscle - Smooth muscle

    • Fibromuscular membrane that fills opening in C-shaped cartilage

    • Allows for esophagus to take up region of windpipe (pass larger things in esophagus)

    • Allows to take up more space for trachea (more air into passageways)

  • lined w/ Pseudostratified Ciliated Columnar Cells w/ Goblet Cells

    • goblet cells → creates mucus (trap debris)

    • Cilia → Propel particulate towards pharynx