RESPIRATORY SYSTEM 11F

7 structures making up respi system

1. External nose

2. Nasal cavity

3. Pharynx

4. Larynx

5. Trachea

6. Bronchi

7. Lungs

Ventilation

Movement of air into and out of the lungs

Respiration

diffusion of gases across cell membranes

2 types of respiration

external - movement of gases between atmospheric air in lungs and blood

internal - movement of gases between blood and body cells

division of respiratory tract

upper - nose to larynx

lower - trachea through alveoli in lungs

upper and lower respiratory tract division

conducting zone - nose to smallest air tubes in lungs. strictly for ventilation.

respiratory zone - solely within lungs. specialized small air tubes & alveoli. gas exchange happens here.

4 simultaneous processes involving gas exchange

ventilation - “breathing” air moves into and out respi passages

external respiration

• site: Lungs (Alveoli and pulmonary capillaries)

• oxygen moves out the alveoli and into blood

• co2 enters from blood to alveoli

gas transport - co2 and o2 travel in blood to and from cells.

internal respiration

• site: Body tissues (Systemic capillaries and cells)

• oxygen from blood into cells

• co2 from cells into blood

respiratory system functions

1. regulation of blood ph (by changing blood co2 levels)

2. production of chemical mediators (angiotensin-converting enzyme for blood pressure regulation)

3. voice production (air moving past the vocal folds)

4. olfaction (when airborne molecules are drawn into the nasal cavity)

5. protection (prevent microorganisms from entering and removing them from respiratory surfaces)

upper respiratory tract

1. external nose

2. nasal cavity

3. pharynx

4. larynx

nose and nasal cavity

nose

• external nose and nasal cavity.

• largest part is composed of hyaline cartilage.

• nose bridge consists of bone.

nares

• nostrils.

• beginning of nasal cavity.

• anterior external openings.

choanae

• extends from posterior openings of nose to pharynx.

hard palate

• floor of nasal cavity.

• separates oral cavity in mouth.

• covered by highly vascular mucous membrane.

nasal septum

• wall of tissue.

• separate nasal cavity into right and left halves.

conchae

• wind turbines.

• three lateral bony ridges on each side of nasal cavity.

• help air churn through nasal cavity.

5 functions of nasal cavity

1. passageway for air (remains open even when mouth is full)

2. cleans the air

• hairs trap large particles of dust

• nasal septum and conchae increase nasal cavity surface area = increased likelihood of air to come in contact with mucous membrane lining nasal cavity

• mucous membrane consists of pseudostratified ciliated columnar epithelium w goblet cells. goblet secrete mucus. cilia sweep mucus posteriorly to pharynx to be swallowed and eliminated by acids in stomach.

3. humidifies and warms air

4. contains the olfactory epithelium

5. helps determine voice sound

pharynx

• common opening of both the digestive and respiratory systems.

• connected to respiratory system at larynx.

• connected to digestive system at esophagus.

nasopharynx

• pharynx region

• most superior. posterior to nasal cavity. superior to soft palate

• (uvula is the extension of the soft palate) which is the partition between naso and oro. it also prevents swallowed material from entering nasopharynx and nasal cavity.

• continuous with middle ear. (auditory tubes)

• its posterior wall houses pharyngeal tonsils or adenoids

oropharynx

• pharynx region

• immediately posterior to mouth and begins at the soft palate

• air food and drink all pass through here

• moist stratified squamous epithelium lining

• palatine and lingual tonsils are found here

laryngopharynx

• spans posterior length of larynx: epiglottis - esophagus

• a small amount of air may be swallowed with food and drink

• moist stratified squamous epithelium lining

larynx

• voice box

• anterior to laryngopharynx

• extend from base of tongue to trachea

• held in place by membranes n muscles superior to hyoid bone

• rigid walls maintain open passageway between pharynx and trachea

larynx cartilages/ligaments

thyroid cartilage

• largest. shield shaped.

• Adam’s Apple

cricoid cartilage

• base of larynx where other cartilages rest

epiglottis

• attached to thyroid cartilage and projects superiorly.

• freely movable flap made of elastic cartilage.

• helps divert food away from trachea opening during swallowing

vestibular folds - false vocal cords

vocal folds - true vocal cords. laryngitis if inflamed

vestibular and vocal folds

• vocal folds vibrate when air passes thru and makes sound

• force of air moving past vocal folds determine sound loudness

• frequency of vibration determines pitch

• skeletal muscles control movement of cartilages in larynx, changing position and length of vocal folds, thus changing pitch of sound

• males have longer vocal folds, lower pitch

• vestibular and vocal folds move medially to close glottis when swallowing, also to prevent passage of air like holding ur breath

lower respiratory tract

1. trachea

2. bronchi

3. tracheobronchial tree

4. alveoli

trachea

windpipe. allows air to flow into lungs. membranous tube attached from larynx to T5. pseudostratified ciliated columnar epithelium with goblet cells.

tracheal rings

• 15-20 C shaped pieces of hyaline cartilage.

• supports anterior (thickest anteriorly) and lateral side of trachea.

• prevents it from collapsing.

posterior - devoid of cartilage and has elastic ligamentous membrane and bundles of smooth muscle.

narrowing of trachea helps expel mucus thanks to smooth muscle contracting

bronchi

carina

• the ridge of cartilage located at the base of the windpipe (trachea) where it splits into the right and left main bronchi leading to the lungs

• its mucous membrane is very sensitive to mechanical stimulation

• stimulates powerful cough reflex when foreign matter touches carina

• beyond it does not stimulate cough reflex

main bronchi - right and left.

tracheobronchial tree

lobar bronchi

• secondary bronchi

• arise directly from main bronchi

• c shaped cartilage rings replaced with cartilage plates

• smooth muscles forms layer between cartilage and mucous membrane

• right lung - 3 lobar bronchi

• left lung - 2 lobar bronchi

• lined with pseudostratified ciliated columnar epithelium

(each lobar bronchus supplies its own section of each lung called “lobes”)

segmental bronchi

• tertiary bronchi

• supply subdivisions within each lung lobe called “bronchopulmonary segments”

bronchioles

• continued branching of the segmental bronchi

• less than 1mm in diameter

• less cartilage more smooth muscle

• lined with ciliated simple columnar epithelium

terminal bronchioles

• several subdivisions of bronchioles

• no cartilage in walls, only smooth muscle

• lined with ciliated simple cuboidal epithelium

alveoli

sites of external respiration.

small, air filled chamber where air and blood come into close contact with each other.

respiratory bronchioles

• have a few attached alveoli

• as it divides more, alveoli attached increases

alveolar ducts

• arise from respiratory bronchioles

• like long branching hallways with many open doorways

• doorways open into alveoli

alveolar sacs

• chambers connected to two or more alveoli at the end of an alveolar duct

alveolar structure

• 300 million alveoli in the two lungs

• diameter of 250 micro meters, thin walls

• cells forming alveolar wall: (1) squamous epithelial cells about 90% (2) surfactant secreting cells for expansion

the respiratory membrane

alveolar walls and surrounding pulmonary capillaries.

location of external respiration.

general components

1. alveolar cell layer

2. interstitial space between alveolar and capillary layer

3. the capillary endothelial layer

lungs

• primary organs of respiration. 2 lobes left. 3 lobes right.

• right lung weight: 620 g

• left lung weight: 560 g

• lobes divided by fissures

• cardiac notch is the medial indentation of left lung where heart lies in between lungs

• bronchopulmonary segments: right lung (10) left lung (9) separated by connective tissue partitions

  • supplied by segmental bronchi

• lobules are the further subdivisions of the bronchopulmonary segments

  • supplied by bronchioles

lung portions

base

• portion of lungs in contact with diaphragm

apex

• portion of lungs extending above clavicle

hilum

• an indentation on the medial surface of the lung

• where structures such as: main bronchus, blood vessels, nerves, and lymphatic vessels enter or exit lung

• all structures passing thru hilum is called “root of lung”

blood supply to lungs

oxygenated blood

• blood that has passed thru lungs and picked up oxygen

deoxygenated blood

• blood that has passed thru tissues and released some of its oxygen

2 blood flow routes to lungs

1. blood flow to alveoli

2. blood flow to tissue of the bronchial tree

Tidal volume

Inspired and expired with each breath 500ml at rest

Expiratory Reserve Volume

Amount of air forcefully expired after normal expiration

Residual Volume

Volume of air still in lungs after most forceful expiration

Inspiratory Reserve Volume

air forcefully inspired after normal inspiration

anatomical dead space

• include all areas of upper and lower respiratory tracts

• all of the conducting zone areas

• volume: 1mL per pound of an individual’s ideal body weight

physiological dead space

anatomical dead space + volume of any alveoli with lower than normal gas exchange

mechanisms of alveolar ventilation

1. alveolar pressure equals atmospheric pressure

2. alveolar pressure is less than atmospheric pressure

3. alveolar pressure again equals atmospheric pressure

4. alveolar pressure is greater than atmospheric pressure

factors affecting alveolar ventilation

1. lung recoil

2. pleural pressure

lung recoil

occurs for two reasons:

1. elastic recoil

2. surface tension - because of hydrogen bonding within alveoli because water molecules in walls attach to center of alveoli, attracted to each other causing it to collapse

surfactant

• preventing alveolar collapse due to surface tension

• mixture of lipoprotein molecules produced by surfactant secreting cells

• infants - Infant Respiratory Distress Syndrome (IRDS)

• cortisol - stimulates surfactant synthesis

pleural pressure

• pressure within pleural cavity: parietal and visceral

• lower than pressure inside alveoli

• pneumothorax

  • separation of visceral and parietal pleurae

  • two causes: penetrating trauma & nonpenetrating trauma

  • treatment: inserting chest tube that aspirates the pleural cavity restoring a negative pressure

  • tension pneumothorax - when a tear in the pleural cavity forms a tissue flap that acts as flutter valve allowing air to enter but not exit

factors affecting diffusion through the respiratory membrane

1. partial pressure gradients (oxygen and carbon dioxide)

2. respiratory membrane thickness (pulmonary edema - accumulation of fluid in alveoli, caused by left-ventricle heart failure)

3. respiratory membrane surface area

transport of oxygen

98.5% is bound to hemoglobin and 1.5% is dissolved in plasma

transport of carbon dioxide

1. dissolved in plasma 7%

2. bound to hemoglobin 23%

3. converted to bicarbonate ion 70%

transport of co2 as bicarbonate ions (reversible)

• carbon dioxide + water - carbonic acid (by carbonic anhydrase)

• carbonic acid dissociates into hydrogen ion + bicarbonate ion

respiratory areas in the brainstem

(1) medullary respiratory center - consists of two sets of neurons

• dorsal respiratory group

  • neurons that are most active during inspiration

• ventral respiratory group

  • neurons that are active during inspiration and expiration

  • pre-Botzinger complex - establish the basic rhythm of respiration

(2) pontine respiratory group - collection of neurons in the pons that help fine tune breathing