Chapter 23Respiratory System

Respiratory SystemF(x):

Respiratory TractConducting Portion:• Nasal cavity > pharynx >

larynx > trachea > bronchi > larger bronchioles

• Has respiratory mucosa• F(x):

Respiratory Portion:• Smallest bronchioles and

alveoli• F(x):

• Psudostratified ciliated columnar epi– Nasal cavity & superior pharynx– Trachea

• Stratified squamous– Inferior pharynx

• Cuboidal with cilia– Smaller bronchioles

• Alveolar epithelium– Simple squamous

Defense• Filtration of debris-

• Mucus escalator-

• Alveolar macrophages-

Upper Respiratory

• Pathway: nostrils (nares) > nasal vestibule (hairs) > nasal cavity (mucus) > internal nares > pharynx > glottis > larynx > trachea > bronchi > bronchioles > alveoli

• Nasal cavity- highly vascularized– F(x): – Divided by nasal septum

• Paranasal sinuses (frontal, sphenoid, ethmoid, paired maxillary & palatine

• Superior, middle, inferior meatuses- between conchae

Pharynx• Nasopharynx• Oropharynx• laryngopharynx

Lower system-LarynxF(x): 9 pieces of cartilage• F(x):

1. thyroid cartilage (Adam’s apple)- larger in males 2. cricoid cartilage3. epiglottis-door to cover glottis during swallowing

– can not swallow food & breathe at same time

4. 3 pairs of: 1. Arytenoid2. Corniculate3. cuneiform

F(x): opening & closing of glottis

VoiceGlottis: vocal folds & rima glottidis (space)• Vocal folds/cords: • Vestibular folds:

• Phonation-• Articulation-• Amplification-

Lower system- trachea

• Windpipe with cilia• Submucosa surrounded by thick

layer of CT• Tracheal cartilage (c-shaped)

Lower system- Bronchial Tree

• Primary bronchi branch from trachea, separated by

• : where primary bronchi, BV’s, nerves, lymphatics enter lung

• Primary- • Secondary

• Tertiary

• Bronchitis-

• Asthma-

Lungs• R: • L:

• Fissures: • Cardiac notch:

• Tertiary bronchus > bronchioles > terminal bronchiole > respiratory bronchiole > alveolar duct > alveolar sac > alveolus

Bronchioles

Alveolus

Alveolar macrophages:

• Each lung ~150mil alveoli

• Simple squamous epi– Type I

pneumocytes:

– Type II pneumocytes:

Membrane for gas exchange

• Alveoli <>capillary• 3 layers– Alveolar epithelium– Capillary endothelium– Basement membrane

• Short distance = rapid diffusion

• Pneumonia-

Respiration

• 3 steps:– Pulmonary ventilation-

– Gas diffusion- – Transport of O2 & CO2- other

tissues

• Hypoxia- vs Anoxia-

Internal-cellular respiration– Absorbing O2 & release of

CO2

External• All processes involved in the exchange of O2 & CO2 between

the body’s interstitial fluids & external environment

Pulmonary Ventilation• Physical movement of

air in/out respiratory tract

• F(x):

• Boyle’s Law• Pressure & volume

inversely proportional• Gases move from

Compliance

• How easily the lungs expand• Less compliance = more force to fill

1. Loss of CT = – Emphysema-

2. Loss of surfactant = 3. Loss of mobility of rib cage = – arthritis

Inhalation / Inspiration

• Elastic fibers of lungs stretch• Ribs Elevate, Diaphragm contracts & moves

inferiorly >

Exhalation

• Quiet Breathing– Inhalation involves muscle contraction, exhalation is

passive– Deep/Diaphragmatic- diaphragm

contraction/relaxation– Costal/shallow- intercostal muscle

contraction/relaxation• Forced Breathing– Exhalation involves contraction of

• Elastic fibers rebound• Diaphragm moves back >

Respiration Volume• Tidal Volume (VT):

• Residual volume:

• Inspiratory Reserve Volume:

• Expiratory reserve volume:

• Inspiratory capacity:

Functional residual capacity:

Vital capacity:

Total lung capacity:

Gas LawsDalton’s Law• Atmospheric pressure:

mixture of all of the gases colliding (N2, O2, CO2, H2O)

• Partial Pressure:

Henry’s Law•

Pulmonary• Capillary blood P CO2 45mm• Alveolar blood P CO2 40mm• So, CO2:

• Capillary blood P O2 40mm• Alveolar blood P O2 104mm• So, O2:

Systemic• Capillary blood P CO2 40mm• Cell P CO2 45mm• So, CO2:

• Capillary blood P O2 95mm• Cell P O2 40mm• So, O2:

Oxygen Transport• Hemoglobin molecules: 4 protein subunits with iron

ions = bind O2 molecules– 1 hemoglobin binds 4 O2 = oxyhemoglobin (HbO2)

• Release of O2 from HbO2:

• Carbon Monoxide Poisoning (CO)– CO wins over O2 in fight for Hb binding > decrease O2 to

tissues > decrease ATP > cell death

Carbon Dioxide

70% Converted to carbonic acid by RBCs

• Uses carbonic anhydrase

• Dissociates into H+ and bicarbonate ion HCO3

(H+ can leave RBC & drop pH of plasma)• Chloride Shift-

Intracellular bicarbonate ions Can move out of RBC in exchange for Chloride

7% Dissolves in plasma

23% Forms HbCO2-carbaminohemoglobin

Control of Breathing

1. Medulla Oblongata-

– Dorsal respiratory group (DRG)- every cycle• Intercostals & diaphragm

– Ventral respiratory group (VRG)- forced breathing• Neurons for maximal inhalation

– Neurons for inhalation are opposite neurons for exhalation

2. Pons-

• Apneustic:

• Pneumotaxic:

3. Higher Brain Centers (cerebral cortex, limbic system, hypothalamus)• Alter activity of

pneumotaxic centers

SIDS

• 2-4 months• Respiratory center is making connections with

other parts of the brain and has a problem with connection > disrupts respiratory reflex

• Higher in smoking homes

Respiratory Reflexes• Sensory info modifies activities of respiratory

centers • Can change rate of respiration

• Chemoreceptors: sensitive to P of gases &pH in blood– Hypercapnia: • Cause: • Stimulates chemoreceptors > medulla > increase

stimulation to respiratory muscles > eliminate CO2

– Hypocapnia: • Cause:

What affects breathing?• Baroreceptors: aortic/carotid sinuses- sensitive to P

– Decrease in BP =

• Stretch receptors: respond to volume in lungs– Hering-Breuer Reflex- inflation & deflation during forced breathing

• Irritants– Protective- sneezing, coughing– Apnea:

• Glottis is forcefully closed, lungs full, blast air out glottis

• Temp, Pain, Emotion- Hypothalamus, Parasympathetic vs Sympathetic

Disorders

Cystic Fibrosis:• genetic disease of secretory epithelia

(mutation affects the movement of chloride ions across the plasma membranes, causing a buildup of mucus)

• Most common lethal genetic disease in Caucasian