CH. 23 - RESPIRATORY SYSTEM
I. RESPIRATION IS:
A. VENTILATION - Air in & out of lungs
B. GAS EXCHANGE
1. Blood Û air
2. Blood Û tissues
C. GAS TRANSPORT in blood
D. CELLULAR METABOLISM
1. ANAEROBIC - 2 ATP/glucose
2. AEROBIC - 36 ATP/glucose
E. FUNCTION - "GORPP"
1. GAS EXCHANGE & VOICE
2. OLFACTION
3. REGULATION OF pH
4. PROTECTION – ê entry, sneeze, cough, hairs, mucus
5. PRODUCTION of VOICE
II. ANATOMY & HISTOLOGY - Lungs & Accessory Structures (Fig. 23.1, p. 821)
UPPER: A. NOSE & NASAL CAVITY (Fig. 23.2, p. 822)
1. EXTERNAL NARES è Vestibule, Strat. Sq. Epith & hairs
2. NASAL CAVITY - lined w/ PCCE & mucous cells
a. Hard palate - floor
b. Conchae - walls, Turbinates
c. Olfactory epith. - roof
d. Nasal septum - divides into 2
e. Nasolacrimal duct - drains into
f. Paranasal sinuses - drain into
3. INTERNAL NARES - to pharynx
B. PHARYNX - Common chamber of Resp. & Dig. systems
1. NASOPHARYNX - Internal nares è Uvula
a. Auditory tube - to middle ear
b. Pharyngeal tonsil
2. OROPHARYNX - Uvula è Epiglottis
3. LARYNGOPHARYNX - Epiglottis è Larynx/Esophagus
LOWER: C. LARYNX - Voicebox, “Adam’s apple”
- Enlarges due to androgens - tone deeper in males
- 9 pieces of cartilage + muscles + ligaments (Fig. 23.3, p. 824)
1. Single (3) a. Epiglottis - elastic
b. Thyroid - shield, hyaline
c. Cricoid - signet ring, hyaline
2. Pairs (3) a. Cuneiform
b. Corniculate
c. Arytenoid
3. Glottis - opening into larynx
D. TRACHEA - “Windpipe”, PCCE (Fig. 23.5, p. 826)
1. Membranous tube, 1/2” diameter, 10-15 cm long
2. “C”-rings, hyaline cartilage supports, 15-20
3. Esophageal groove, opens posteriorly
E. 10 BRONCHI - to lungs, PCCE, carina - branch (Fig. 23.6, p. 828)
1. Right - more vertical, wider, é infections/inhaled objects
2. Left - more horizontal, narrower
F. LUNGS
1. Hilum - where main (1o) bronchi enter lungs
Conduct. 2. Lobar (2o) bronchi (PCCE) è
zone a. R. lung has 3 + 3 lobes
b. L. lung has 2 + 2 lobes
3. Segmental (3o) bronchi (PCCE) è lobules (Fig. 23.9, p. 832)
(p. 828) 4. Bronchioles - no cartilage rings, é C.T., ésmooth muscle
a. Asthma-constriction of smooth muscle
Resp. zone 5. Terminal bronchioles (ciliated, simple cuboidal) è
(p. 829) respiratory bronchiolesèalveolar ductsèalveolar sacè
alveoli (simple sq.) (300 million!) = GAS EXCHANGE
G. MUSCLES of RESPIRATION (Fig. 23.10, p. 833)
1. Inspiration - é thoracic volume, expands depth
a. Diaphragm - most important
b. External intercostals - expands width
2. Expiration -ê thoracic volume, mostly passive recoil
a. Abdominal - forcibly contract
b. Internal intercostals - “ “
H. PLEURA (Fig. 23.12, p. 835)
1. Visceral
2. Parietal
3. Fluid - lubricates & holds membranes together
I. BLOOD SUPPLY
1. Pulmonary - Deoxygenated in, oxygenated out
2. Systemic a. Supplies alveoli w/blood
b. Dumps deoxy into oxygen. blood, <1%
III. VENTILATION
A. BREATHE
1. ê pressure in lungs (vacuum) è opens lungs è air in
2. é pressure in lungs èê space in lungs è air out
B. CHANGING LUNG/ALVEOLAR VOLUME
1. REDUCED BY:
a. Recoil of elastic fibers
b. H20 surface tension of fluid lining alveoli
2. EXPANDED by:
a. Surfactant - lipoprotein, ê surface tension, 7 mos. fetus
b. Pleural pressure, "suction effect", pleural fluid holds visceral &
parietal pleurae together, like “syringe & plunger”
3. COLLAPSE - lung recoil greater than surfactant or pleural pressure
C. COMPLIANCE - Ease with which lungs expand
êby: 1. Collapsed alveoli
2. Obstructed airway - asthma, bronchitis
3. Depositing of inelastic fibers
IV. MEASURING LUNG FUNCTION - PULMONARY VOLUMES & CAPACITIES (p. 842) [LAB]
A. VOLUMES - 5800 ml = 6 L total
1. Tidal volume (T.V.) normal breath = 500 ml
2. Inspiratory reserve (I.R.) deep breath = 3000 ml
3. Expiratory reserve (E.R.) reserve exhale = 1100 ml
4. Residual vol. (R.V.) can’t exhale, keeps lungs inflated =1200 ml
B. CAPACITIES - 2 or more volumes combined
1. Inspiratory capacity = T.V. + I.R.
2. Functional residual cap = E.R. + R.V.
3. Vital capacity = I.R. + T.V. + E.R.
4. Total lung capacity = V.C. + R.V. = 5800 ml
5. Vital Capacity
a. 20-25% higher in young, tall, thin males
b. Can é 30-40% w/exercise
c. Forced Expir. V.C. = Max inspir, then max expir. Rate
C. MINUTE RESPIRATORY VOLUME = How much/min
1. M.R.V. = T.V. (500 ml.) X Resp. rate (12/min) = 6000 ml./mi
V. PHYSICS OF GAS EXCHANGE
A. PARTIAL PRESSURE (Tab. 23.2, p. 843)
1. 760 mm Hg @ sea level
2. PN2 = 597.5 mm Hg = 78.6%
3. PO2 = 158.4 mm Hg = 20.8%
4. Gases diffuse from air Ûliquid to equilibrate, [Hi]è [Lo]
5. Henry’s Law: [Dissolved gas] = partial pres X sol. coefficient
a. CO2 solubility coefficient is 24X > than O2
B. RESPIRATORY MEMBRANES (Fig. 23.8, p. 831)
1. 6 layers to cross – KNOW!
2. Diffusion gradient/direction determined by partial pressure
3. 4 factors determine RATE of gas exchange:
a. Thickness
b. Diffusion coefficient: CO2 20X > O2
c. Surface area of alveoli = 70 m2 = 1/2 tennis court
d. Gradient - difference in partial pressure across membrane
C. VENTILATION & CAPILLARY BLOOD FLOW
1. é ventilation or éblood flow è é gas exchange
2. Local control:
a. Tissues, precap sphincters open when O2 low, CO2 hi
i.e. exercise é demand for O2 & for CO2 to be removed
VI. O2 & CO2 TRANSPORT IN THE BLOOD
A. O2 (Fig. 23.16, p. 846)
1. 98.5% via Hgb = OXYHEMOGLOBIN, 1.5% in plasma
2. Diffusion gradient: Hi PO2 outside è low PO2 inside
160 in air è104 in alveoli è95 in pulmonary veins, systemic
arteries & capillaries è40 interstitial fluid. è20 in cells (ETC)
3. At PO2 of 80 mmHg and above, Hgb is 95% saturated
- at 104 (pulmonary capillaries), Hgb is 98% saturated
4. Hgb releases 23% of its O2 @ rest, 75% of its O2 in exercise
(Fig. 23.17, p. 849)
5. Bohr Effect = ê ability of Hgb to hold O2 (Fig. 23.18, p. 849)
due to: a. é CO2
b. ê pH (acidic) Tissues & capillaries
c. étemperature
6. Reverse Bohr effect seen in lungs, éability of Hgb to hold O2
B. CO2
1. Opposite gradient to O2 (Fig. 23.16, p. 846)
2. 46 in tissues è 45 interstitial fluid & veins. è 40 in alveoli è
27 expired air è 0.3 in air
3. Transportation in 3 ways:
a. 7% in plasma
b. 23% w/ Hgb = CarbaminoHgb
c. 70% as HCO3- ions (Bicarbonate) (Fig. 23.19a, p. 851)
carbonic anhydrase
CO2 + H2O Û H2CO3 Û H+ + HCO3-
4. Chloride Shift (Fig. 23.19b, p. 851)
a. [HCO3-] gets hi in RBC è diffuses into plasma
b. RBC loses (-), imbalance in charges
c. Cl- diffuses into RBC to replace lost HCO3-
d. Process reverses in lungs
5. Can unload CO2 as quickly as O2 taken up
VII. CONTROL/REGULATION OF RESPIRATION (Fig. 23.21, p. 854)
A. NERVOUS - Respiratory center in medulla & pons (Fig. 23.20, p. 852)
1. Inspiration - rhythmic, spontaneous
2. Expiration - normally passive, so it is inactive
- inhibits inspiration when deep breathing
3. Hering-Breuer Reflex - lungs, prevents over-inflation, saves NRG
B. VOLUNTARY - conscious control, stop, start, rate
C. CHEMICAL - Chemoreceptors - central & peripheral (Fig. 23.22, p. 855)
1. IF CO2 é in blood è ê pH è é respiratory rate
éCO2 pH ê CO2 + H2O Û H2CO3 Û H+ + HCO3-
2. IF é PCO2 by 5 mm Hg è é respiratory rate by 100%
3. PO2 less sensitive, must ê by 50% to cause é respiratory rate
D. OTHER - Touch, temp., pain & exercise stimulate respiratory center