Unit 5&6

Conducting Zone (no gas exchange)

Send air to respiratory zone

Structures:

Nasal & oral cavities

Pharynx & larynx

Trachea

Bronchi

Terminal bronchioles

Respiratory Zone (gas exchange)

Receive air from conducting zone

Structures:

Respiratory bronchioles

Alveolar ducts

Alveolar sacs

Alveoli

4 function of the respiratory system

Ventilation – move air in & out of lungs

Transportation – oxygen & carbon dioxide between lungs & tissues

External respiration – gas exchange between lungs & blood

Internal respiration – gas exchange between blood & all body cells

Nasal Cavity

Provides an airway for respiration

Moisten, warm or cool, filter air

Resonating chamber (speech)

Olfactory receptors

Vibrissae

moist hairs that filter particles

Respiratory mucosa

Lines the remainder of the nasal cavity

Mucus contains lysozyme

Destroys bacteria

Nasal mucosa and conchae 

Inhalation: filter, heat, & moisten air 

Exhalation: reclaim heat & moisture 

Larynx (voice box) functions

Airway to the lungs

Voice production

Speech

release of expired air while opening and closing glottis

Loudness

forces of air rushing across vocal cords

Trachea 3 layers 

Mucosa- goblet cells (mucus) & cilia

Submucosa – connective tissue

Adventitia – hyaline cartilage w/ C-shaped rings

Alveoli

(300 million)

Most of the lungs’ volume

↑Surface area (gas exchange)

Alveolar structure 

surrounded by elastic fibers & capillaries 

Type I alveolar cells function

Gas exchange

Type II alveolar cells function

secrete surfactant (soap)

Alveolar pores 

connect alveoli 

equalize air pressure throughout lung

Pulmonary circulation

RV → Pulmonary trunk → pulmonary arteries → pulmonary capillaries (surrounding alveoli) → pulmonary veins → LA

Inspiration

air enters lungs

diaphragm & external intercostal muscle

Rib cage rises and expands

Intrapulmonary pressure decreases below atmospheric pressure

Expiration 

air exits the lungs 

diaphragm & external intercostal muscles relax

rib cage lowers

lung volume decreases intrapulmonary pressure rises above atmospheric pressure

Boyle’s law

Inverse relationship between volume and pressure of gases

Atmospheric pressure

pressure exerted by air surrounding the body

Intrapulmonary pressure 

pressure w/in alveoli 

Intrapleural pressure

pressure w/in pleural cavity

Transpulmonary pressure

intrapulmonary pressure - intrapleural pressure

Friction 

major source of resistance to airflow 

Relationship between flow (F) & resistance (R)

Increased R → decreased F

Decreased R → increased F

Surface tension

attraction of water molecules for one another

Surfactant 

Soap-like

Prevents alveoli from collapsing 

Forced inspiration 

diaphragm, external intercostals, sternocleidomastoids scalenes, pectoralis minor contract 

Forced expiration

internal intercostals, abdominal muscles contract

Tidal Volume (TV)

air moving into & out of the lungs w/ each breath (500mL)

Inspiratory Reserve Volume (IRV) 

air inspired forcibly beyond tidal volume (3100 mL) 

Expiratory Reserve Volume (ERV)

air evacuated from the lungs below tidal volume (1200mL)

Residual Volume (RV)

air remaining in lungs after forced expiration (1200mL)

Vital Capacity (VC) 

amount of exchangeable air during normal breathing (4800mL) 

TV+IRV+ERV= VC

Total Lung Capacity (TLC)

maximum amount of air that can be held in the lungs (6000mL)

VC+RV=TLC

Respiratory Rate (RR) 

total breaths per minute (BPM) 

Respiratory Minute Volume (RMV)

normal air volume exchanged per minute (mL/min)

RRxTV = RMV

Forced Vital Capacity (FVC)

air forcibly expelled after taking a deep breath

Forced Expiratory Volume (FEV) 

air expelled during time interval (1.0 sec) 

Obstructive disorders

asthma, bronchitis emphysema

abnormal FEV

Normal VC

Restrictive disorders

Pulmonary fibrosis, black lung, white lung, all others 

normal FEV

abnormal VC

Eupnea

Normal respiratory rate & rhythm

RR = 12-18 per min

Apnea

cessation of breathing

Dyspnea 

difficult or labored breathing 

often occurs in people who smoke 

Hyperventilation

above normal rate & depth of breathing

Hypoventilation

below normal rate & depth of breathing

Shortness of breath 

reduced ability to inhale completely 

Anoxia

severe oxygen deficiency

Pneumothorax

Pressure of atmospheric air between parietal pleural & visceral pleural membrane

caused by chest wall perforation

may lead to atelectasis

Atelectasis 

collapsed lung 

caused by chest wounds or tearing of pleural membranes 

COPD

Chronic bronchitis & emphysema

respiratory failure, hypoxia, CO2 retention, respiratory acidosis

Asthma

Characterized by: dyspnea, wheezing, chest tightness

Airway inflammation

Immune response to dust mites, cockroaches, dander, pollen, mold spores, rubber particles

Stimulates IgE (recruits inflammation)

Airways thickened w/ mucus (obstruction)

Sense of panic

Tuberculosis 

Infectious disease

Cause: airborne bacterium Mycobacterium tuberculosis

Resistant strains are increasing

Symptoms: fever, night sweats, weight loss, coughing, severe headache, blood in sputum, destruction of lungs & other body organs (“consumption”)

Treatment: 12-month course of antibiotics

Bronchogenic Carcinoma

⅓ of cancer deaths (U.S.)

90% of lung cancer patients were smokers

Emphysema

Destruction of alveolar walls

Chronic inflammation

Loss of lung elasticity

Collapse of bronchioles during expiration

Typically caused by: smoking

Bronchitis 

↑Mucus production

Inflammation

Frequent infections

Causes: inhaled irritants (smoke, chemical fumes, dust, microbes)

Pneumonia

Inflammation of lung passages & spaces

Fluid accumulation w/in alveoli

↓Gas exchange (hypoxia)

Potential for severe illness, death

Mainly caused by viruses & bacteria

Cystic Fibrosis (CF)

Overproduction of mucus

Blocks: respiratory passageways, pancreatic duct, common bile duct

Recessive genetic disease

Caused by a faulty gene that codes for thickened mucus

Nitrogen symbol and percentage 

N2

78.60%

Oxygen symbol and percentage

O2

20.90%

Carbon Dioxide symbol and percentage

CO2

0.04%

Water symbol and percentage 

H20 

0.46%

Partial pressure definition

pressure extended by a single gas in a system (atmosphere, blood, tissues, lungs )

Sea level pressure

760mmHg

Equation of partial pressure 

% of gas X total pressure 

Pulmonary ventilation

Air exchange between atmosphere & lungs (breathing)

Depends on chest & diaphragm movements & clear airways

Inhalation decrease pressure inside lungs

Exhalation increase pressure inside lungs

External Respiration

Gas exchange between lung alveoli & pulmonary circulation blood

Depends upon :

Gas partial pressure differences

Lung membrane health

Blood flow into & out of lungs

Internal Respiration 

Gas exchange between blood & body cells 

Depends upon: 

Gas partial pressure differences 

Blood ←> cells 

Law of Diffusion

Gases move from a region of HIGH partial pressure to a region of LOW partial pressure

Venous blood oxygen and location in PO2

40mmHg

Blood in the lungs

Alveolar oxygen and location in PO2

104mmHg 

Air in the lungs 

Venous blood carbon dioxide and location 

46mmHg 

Blood at lungs 

Alveolar carbon dioxide in PCO2

40mmHg

Air in lungs

How much more soluble is CO2?

20x more soluble in plasma than oxygen

CO2 transport that is dissolved in plasma percentage? 

10% 

CO2 transport chemically bound to Hemoglobin in the RBC percentage?

20%

CO2 transport as a bicarbonate Ion (HCO3-) in Plasma percentage?

70%

O2 transport dissolved in plasma percentage? 

1%

O2 transport chemically bound to Hemoglobin in the

Oxyhemoglobin and locations?

Forms when an O2 molecule reversibly attaches to the heme group of hemoglobin

Hb + O = HbO2 (in lungs)

HbO2 → Hb = O2 (at body cells)

Carbaminohemoglobin and locations? 

Forms when a CO2 molecule reversibly attaches to the heme group of hemoglobin 

Hb+ CO2= HbCO2 (AT BODY CELLS )

HbCO2-> Hb+ CO2 (AT LUNGS) 

Carboxyhemoglobin and locations?

Forms when a CO molecule irreversibly attaches to the heme group of hemoglobin

Hb + CO = HbCO

HbCO → Hb + CO

Carbonic Acid and locations?

Forms in RBC when CO3 catalyzes water to combine w/ CO2 to form CO3

CO2+ H20= H2CO3 → H+HCO3- (AT LUNGS)

H+HCO3- → H2CO3 → CO2 + H20 (AT BODY CELLS )

Bicarbonate Ion 

Forms in RBC when carbonic acid breaks down to release hydrogen ion & bicarbonate ion 

H2CO3 → H+ HCO3- 

Chloride Shift in Tissue Capillaries

As RBCs move through tissue capillaries, they take in CO2 & release the bicarbonate ion to the plasma

As bicarbonate ion LEAVES, CI- shifts into the RBC in order to replace the negative bicarbonate ion (HCO3-)

Preserves charge balance in RBC

Chloride Shift in Pulmonary Capillaries

As RBCs move through pulmonary capillaries, they take in the bicarbonate ion from the plasma & release CO2 to the plasma

As the bicarbonate ion (HCO3-) shifts into the RBC from plasma, CI- shifts out of the RBC to the plasma

Preserves charge balance in RBC

4 Factors that Induce Hemoglobin to Unload O2

Increased Temp (Root Effect)

Increased H+ from acids (Bohr Effect)

Increased H+ from CO2 (Bohr Effect)

Increased 2,3 diphosphoglycerate (DPG)

Causes a right shift in the O2 dissociation curve

Influence of the Bohr Effect on hemoglobin saturation

Increase CO2 in blood

Increased CO2 = O2 is released and saturation decreases

Decreased CO2= hemoglobin hold O2 and saturation increases

O2 dissociation Curve shifts to right

Right-shift decreases ability of hemoglobin to hold O2

Results in additional O2 unloaded to cells

When pH is decreased, O2 saturation decreased from 75% to about 65%

This makes an extra 10% O2 available during any increase in physical activity

Pneumotaxic center location 

Pons 

Pneumotaxic center

Secondary respiratory centers

Modify the basic respiratory rate

P

Apneustic center location

Pons

A

Apneustic center 

Secondary respiratory center 

modify the basic respiratory rate 

A

Medullary respiratory center location

Medulla Oblongata

Medullary respiratory center

Primary respiratory center

Sets basic respiratory rate

Pneumotaxic function 

Inhibits inspiration 

Apneustic function

Stimulates inspiration

Medullary function

stimulates basic breathing

Dorsal respiratory group

Issues output to the VRG that modifies the respiratory rhythm to adapt to varying conditions

Hering - Breuer Reflex 

Inflation reflex 

Lung stretch receptors are stimulated by lung inflation

Sends signal to medullary center to stop inspiration and allow expiration

Prevents over-inflation of lungs and damage to the alveoli