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Anatomy and Physiology of the Upper and Lower Respiratory Tract

Respiratory System

involved in gas exchange

Functions of the Respiratory System

1. Respiration - ventilation
2. pH Balance in the blood
3. Olfaction
4. Protection
5. Voice Production


- mechanical
- act of moving air in and out of the lungs
- necessary for gas exchange

pH Balance in the Blood

↑ of CO₂ ↓ blood pH, management of CO₂ will manage the pH level in the blood


specialized adaptations for inhalation of pathogens


smell depends on inhalation

Voice Production

sounds are made by the movement of air


study of the lungs

Upper Respiratory Tract

1. nose
2. nasal cavity
3. pharynx

Lower Respiratory Tract

1. larynx
2. trachea
3. bronchi
4. lungs



Functions of Nasus

1. taking in air
2. acts to warm, cleanse, and humidify air
3. olfaction - detects odors
4. acts to amplify the voice

Upper Region - bridge of the nose

1. made of 2 nasal bones - fragile
2. determines medial shape

Lateral side of nasus

a. Maxillary bones
b. Defines the wideness of the nasal cavity

Extension from nasus

a. Contains lateral cartilage - forms sides of nose
b. from nasal bone
c. Ala Nasi

Ala Nasi

wings of the nose, round portion on the sides of the nose
i. Contains Alar cartilage
ii. Provides wing shape


a. Small depression above the upper lip
b. Non-functional in humans

External Nares

Openings of the nose (nostrils)

Right and Left External Nares

1. nasal cavities
a. Separated by cartilage wall - nasal septum
b. lined with pseudostratified epithelium
c. secretes mucus - which prevents from drying out, captures small particles in the mucus
d. ciliated push stuff out of the nasal cavity into the throat and into the digestive tract

Nasal Septum

a. Made of septal cartilage
b. Anchored by Vomer inferiorly
c. separated by Ethmoid (Superior)

Hard Palate

Located on floor of nasal septum
a. Consists of palatine bone
b. There is a mucus membrane cover
c. Boundary between nasal and oral cavity - ability to chew and breathe at the same time

Roof of Nasal Cavities

a. Comprised of sphenoid and ethmoid bone
b. Covered by Olfactory mucosa

Olfactory Mucosa

detects odors


1. located on the anterior portion of the nasal cavity
2. tiny guard hairs to prevent foreign matter from entering
i. Can be triggered by Trigeminal nerve to initiate sneezing

Nasal Conchae

a. 6 spiraling bones- 3 in each nostril
i. Superior - covered olfactory mucus - sinuses
ii. Middle - sinuses
iii. Inferior - sinuses below inferior conchae connects to nasolacrimal duct
b. below nasal conchae is a meatus

Nasolacrimal Duct

primary drainage for tears that is excreted with mucus

Paranasal sinuses

1. extended from meatus
2. hollow spaces within bone
3. Lined with moist mucus membrane
4. Acts to provide resonance to voice
5. Decreases the mass of the head


1. in the rear of nasal cavity
2. aka internal nares
3. opening of nasal cavity to the larynx

Deviated Septum

nasal septum angles slightly off to 1 side or the other
1. Occurs in 10-20% of people
2. Common birth defect
3. Caused by nasal injury

Deviated septum affects....

a. Quality of voice
b. Creates pockets where mucus accumulates - can increase infection


Persistent Nose Bleeding
1. trauma to base of nasal septum
2. Nose is highly vascular
3. Atmospheric pressure and humidity can cause epstaxis

sinus infectons

buildup of mucus in the sinuses
1. An infection results from bacteria being trapped in the sinuses
2. Membrane may swell and form sinusitis


swelling of nasal membrane
a. Inflammation of the sinus cavity
b. traps mucus
c. persistent - because bacterial will hide and spread throughout the ear, nose, and throat
d. deviated septums, or people with smaller sinuses are more prone to sinus infections
e. surgery can enlarge sinus cavities

Sneezing Reflex

response to nasal irritation
i. Mediated by the CN - V, Trigeminal Nerve
ii. Expels stuff that shouldn't be in the nose
iii. Small percent of people(1-4) - contains a branch in CN-V associated with vision and visual stimulation.
1. Causes people to sneeze when they see the sun.

Pharynx (Throat)

1. part of digestive and respiratory tract
2. moves food, liquid, air to respective locations

Structure of Pharynx

1. two inferior branches - one to digestive tract and one to respiratory tract
2. 3 regions of Pharynx

3 Regions of Pharynx

1. Nasopharynx
2. Oropharynx
3. Laryngopharynx


1. receives air from the nose
2. Posterior to Choanae
3. Floor - formed by a soft palate
3. Closes pharynx when swallowing which prevents a up flow of food
4. contains Uvula
5. Openings that lead to auditory and Eustachian tubes (connection to middle ear and nasopharynx)
6. home of pharyngeal tonsil


1. extends form soft palate, posterior end of soft palate

soft Palate

soft tissue extension of hard palate

Eustachian Tubes and Nasopharynx Function

1. used for pressure regulation within the ear
2. Vulnerable to infections - which can travel to the ears

Structure and location of Oropharynx

1. cavity behind the mouth
2. Begins at soft palate ends at epiglottis
3. Lined with moist stratified epithelium
4. Home of palatine and lingual tonsils
5. Terminates at Epiglottis - fold of elastic cartilage that angles upwards

Functions of Oropharynx

1. Common passageway for all food, drink, and air
2. Acts as door to lower respiratory tract
3. Prevents food from going to larynx
4. Fold will cover up the passageway to the larynx to allow only food and drink to go through the laryngopharynx


1. Esophagus
2. directs food to the digestive tract


1. anterior part of throat
2. Extends from base of tongue to trachea
3. Consists of 9 masses of cartilage - joined together by small muscles and ligaments
4. Supported by hyoid bone
5. Thyroid Cartilage
6. On either side of larynx - there are 2 pairs of ligaments
7. receives air from oropharynx and sends to trachea

Hyoid Bone

which is suspended, anchors muscle to tongue, and does not articulate with another bone in the body
i. Required for speaking

Thyroid Cartilage

1. (adam's apple)
2. Smaller in women
3. Reason why men have lower voices - result of thickened and lengthened vocal cords
4. Opening is protected by epiglottis

2 Ligaments on either side of Larynx

1. False Vocal Cords
2. True vocal cords -

False Vocal Cords

vestibular folds, larger


space between the false and true vocal cords

True Vocal Cords

1. inferior vocal folds
2. Responsible for voice production

Voice Production is caused by

vibrations in vocal folds - changing tension and vibrations
3. Air is flowed over picking up vibrations
4. Sound is modified by actions of lips, tongue, and teeth

Factors that affect the sound of base voice

1. thickness and length of vocal cords
2. shape of teeth: affects base of voice
3. shape and size of nasal cavity

Trachea (windpipe)

1. Membranous tube
2. Begins at bottom of larynx
3. Runs to T5
4. Average length 10-12 cm, 12 mm wide
5. 15-20 cartilage rings (c-shaped bands of cartilage) - props the trachea open
7. Lined with pseudo stratified ciliated epithelium
8. Goblet cells that make mucus
9. Cilia pushes mucus from trachea up to larynx through laryngopharynx

Cough Reflex

1. initiated by blockage in trachea
2. Trachalis (smooth muscle) triggers coughing to move stuff out
3. Irritated of inflammation of trachea will cause a cough, respiratory infections

Persistent Inflammation of Trachea

pseudostratified epithelium will turn into stratified squamous epithelium and loses its ability to move mucus
i. Ie) smoker's cough

Purpose of Goblet cells

makes mucus to catch particles, preventing particles from getting to the lung

2 Primary Bronchi

1. two branches at the bottom of the trachea
2. attached to Carina
3. leads into right and left lungs, respectively
4. Left bronchi is more horizontally oriented
5. right bronchi allows stuff to move through more efficiently


last cartilage ring on trachea links to bronchi


1. Primary Respiratory Organs
2. Right and Left one
3. Cone shaped
4. Base of each lung rests against diaphragm
5. Apex comes up 2.5 cm under clavicles
6. Contains tons of elastic tissue for expanding and condensing
7. Found in the Pleural cavity of the Thoracic Cavity
8. Right lung is bigger than left because of the heart
9. Divided into 3 lobes
10. Within in each lobe - divided into segments - Broncho Pulmonary Segments

Pleural Cavity

1. Enclosed by membrane sac that surrounds the lungs
2. 2 layers - Parietal Pleura and Visceral Pleura -
3. Pleural cavity is filled with pleural fluid

Parietal Pleura

lines thoracic cavity and covers parts of diaphragm

Visceral Pleura

covers surfaces of lungs

Pleural Fluid

that lubricated membrane of lungs


1. inflammation of the pleural cavity
2. Result of infection
3. Most common cause of death in post thoracic surgery

3 Lobes of the Lungs

1. Superior - Rt and left lung, anterior
2. Middle - rt lung only, posterior
3. Inferior - rt and left lung, anterior

Broncho Pulmonary Segments

1. 9 segments each of the left lung's lobes (18 segments left)
2. 10 segments each in rt lung's lobes (30 segments Rt)
3. Contains septums between segments
4. Segments can be removed and will not affect the lung's functions

Bronchial Branching in the lungs

1. Primary bronchi - 2- in each lung
2. Branches into lobar bronchi (5) - secondary bronchi - 3 to right lobes and 2 to left lobes
3. Branches in to segmental bronchi (48) - tertiary bronchi - 30 in the right, 18 in the left lung
4. 16 generations of branching within each segment
5. Within 16 generations are bronchioles (small bronchi) - each ends in terminal bronchiole
6. Branch into respiratory bronchioles - 7 generations of branching
7. Alveolar ducts - terminate in the alveoli
8. 300 million air sacs - performs gas exchange


1. thin walled sacs
2. Gas exchange occurs here
3. Lined with thin respiratory membrane
4. Made of pulmonary capillaries
5. Pneumocytes - 2 varieties

Types of Pneumocytes

a. Type I
b. Type II

Type I Pneumocytes

form simple squamous epithelium
i. Participates in most gas exchange

Type II Pneumocytes

1. form simple cuboidal epithelium
2. Participates in little gas exchange
3. Secretes surfactant


1. lubricating fluid
2. Easier for alveoli expansion
3. Prevents walls from sticking to each other

Bronchial Circulation

1. aka lung circulation, lungs own blood circulation system
2. Blood comes from systemic circuit
3. Branch off the aorta - bronchial arteries that get into the capillaries of the lungs
4. Blood drains into bronchial veins - return CO2 blood to the heart


1. process of moving air in and out of the lung, achieved by surrounded muscles
2. 2 Parts

Inspiration (Inhalation)

1. Diaphragm, external intercostals, scalenes, and pectoralis minor elevate the ribs and sternum
2. Diaphragm moves down, ribcage elevate, chest cavity expands
3. Pressure within alveoli decrease, air will move into the lungs
4. Labored breathing = forceful contraction= more air flow

Expiration (Exhalation)

1. Internal intercostals, abdomen muscles
2. Ribcage depresses, diaphragm rises, and Chest cavity shrinks
3. Increase in pleural pressure (pressure within the pleural cavity), causes air to be forced up and out of the lungs
4. Aided by elastic recoil or lung recoil


1. measure of how easily the lungs expand
2. = L of air/cm of H2O
3. Normal compliance in adults = .13 L of air/cm H2O

Factors that cause low compliance

a. Pulmonary edema - fluid buildup in tissue
b. Pulmonary fibrosis - lung scarification
c. Lung cancer
d. Bronchitis
e. Asthma
f. Collapsed lung - due to injury

Factors that cause high compliance

1. Exercise
2. Patients with emphysema

Tidal Volume (TV)

1. amount of air inhaled and exhaled in a standard breathe
2. 500mL

Inspiratory Resolve volume (IRV)

1. amount of additional air that can be exhaled after Tidal Volume
2. 3000mL

Total Respiratory Capacity (TRC)

1. TV + IRV
2. 3500mL

Expiratory Reserve Volume (ERV)

1. amount of air that can be forcefully exhaled after TV
2. 1100mL

Residual Volume (RV)

1. amount left over in the lungs
2. 1200mL

Functional Residual Capacity (FRC)

1. ERV + RV
2. 1100 + 1200 = 2300mL

Vital capacity

1. max. air exhaled after max air inhaled
2. TIC + ERV
3. 4600mL

Total lung Capacity

1. maximum amount of air the lungs can hold
2. TV + IRV + RV+ ERV
3. 5600mL

Factors that Affect Total Lung Capacity

1. Values for males are higher than females
2. size of lungs
3. body size
4. physical condition
5. age affects vital capacity

Factors that decrease Vital Capacity

1. Pulmonary disease
2. Tumors
3. Fibrosis
4. Tumor deformities

Factors that increase Residual volume

1. Not pushing air out
2. Emphysema

Minute Ventilation

how much air movement/min.
1. = TV x Respiratory rate (breathes/min)
2. =500mL x 12 b/min = 6000mL/min or 6L/min

Medullary Respiratory Center

1. regulates Ventilation
2. located inMedulla Oblongata
3. contains 2 Dorsal Respiratory Groups and 2 Ventral Respiratory Groups
2.Modifies base rhythms

2 Dorsal Respiratory Groups

stimulate contraction of diaphragm

2 Ventral Respiratory Groups

controls intercostals and abdominals and controls rhythm of respiration
1. Sets base rhythms

MRC modifies base rhythms on?

a. Blood gas levels
b. Body temp - metabolism increases, increases respiration rate
c. Bodily movements - more fuel needs for O2
d. Emotional state - Increases or decreases RR
e. Relaxation - decrease breathing

Pontine Respiratory Center

1. Responsible for switching between inspiration and expiration
2. causes Hering- Breur Reflex

Hering-Breur Reflex

1. prevents over inflation of lungs
2. Within the pontine respiratory group begins to inhibit muscles to relax lung
3. Occurs 2 sec after inhalation
4. Triggered by stretch receptors of the lungs
5. Inhale for 2sec, exhale for 3 sec

Mechanisms that Regulate Ventilation

1. Medullary Respiratory Center
2. Pontine Respiratory Center
3. CO2 and O2 levels in the blood
4. conscious thought

Regulation by CO2 levels

small increases causes breathe rate to increase, breathe in longer and harder
a. 5% rise of CO2 will increase breathe rate 2x

Regulation by O2 Levels

decrease in O2, increase breathe rate to compensate
a. At rest, you consume double the amount to conserve
b. Hypoxia doesn't settle in until about below 50% normal level
c. A decline in respiratory center function, stops breathing and will result in death


- ability to stop breathing

Reason why conscious thought can regulate ventilation

1. Function to control Speech
2. Requires control of breathing
3. Requires conscious override
4. Correlation between conscious thought and breathing

Partial Pressure in the Lungs

1. gas diffusion in the lungs
2. Increase pressure of O2 in lungs is higher than blood stream, causes a diffusion into blood, therefore pressure of O2 in lungs decrease
3. Increase pressure of CO2 in blood is higher than in lungs, causes diffusion into lungs, thus CO2 in blood decreases
4. CO2 diffuses faster than O2 - loss of O2 diffusion capability will go first and faster compared to CO2

Effects of CO2 and O2 Diffusion

1. Increase CO2 in body will cause increase in respiratory rate, Acidosis can occur
2. Loss of 2/3 and 3/4of respiratory membrane - severe consequences like cancer, emphysema, and surgical removal of parts of lungs will decrease surface area for diffusion of gas
3. TB, smoking, black lung, inflammation can also cause inflammation with alveoli -resulted from loss of cilia
4. Fluid buildup causes edema in tissue that will decrease gas exchange - due to a thickened respiratory membrane


inflammation of bronchi
a. Usually a temporary condition resultant from irritation or infection
b. Caused by infection, cigarette smoke, pollution
c. Swelling of respiratory membrane
d. Difficult into O2 consumption
e. Decreased ability to get rid of mucus
f. Decreased ventilation

Chronic Bronchitis

a. Resultant of smoking and pollution in environment
b. Destruction of cilia
c. Forceful coughing is only possible - which leads to more irritation
d. Can cause emphysema


walls of alveoli break down, air sacs are destroyed
a. Can occur with and without chronic bronchitis

Chronic Obstructive Pulmonary Disease (COPD)

emphysema + chronic bronchitis
a. Domino effect of alveoli loss
b. More irritation and progressive loss of alveoli
c. Fluid will pool within lung causing pneumonia
d. Progressive condition
e. More than 80% are smokers

Effects of COPD

i. Worsening Shortness of breathe
ii. Partial Surgical removal of lungs
iii. Required need for O2 tanks
iv. Transplant may result

Bronchogenic Cancer

aka Lung Cancer
a. Includes neck and throat cancers
b. Arises from endothelium of respiratory rate
c. Highest cancer type
d. Tendency to sneak up, no noticeable signs until too late
e. Increase vascularity will cause metastasis to other areas
f. Genetic predisposition
g. 75% that develop are smokers, 25% live with smokers

Effects of Exercise on Respiration

1. increases breathing
2. Within 4-6 min., most people reach max. Respiratory rate (depending on physical condition)

Anaerobic Threshold

max respiratory rate is reached, will cause you to go into anaerobic respiration, buildup of lactic acid

Factors that affect Respiration with Age

1. Decreases vital capacity
2. Decreased max. ventilation rate
3. Decreased capacity for gas exchange
4. Respiratory membrane thickens, decrease in gas exchange
5. Muscular action decreases, increase in breathe rate
6. Costal cartilage will ossify which causes less expansion
7. Results in fluid build up, decreased cilia
8. Breakdown of elastic tissue, will allow you to expand lungs out which does allow exhalation easily, thus increases residual pressure

Athletic Training can...

3. Increases vital capacity
4. Decreases reserve volume
5. Decrease tidal volume - consumed more air
6. Minute Ventilation = 180L/min, 50% possible increase

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