A & P Respiratory System

What tissue types are present?

- pseudostratified ciliated columnar epi
- simple squamous
- non-keratinized stratified squamous
- simple cuboidal
- hyaline cartilage
- elastic cartilage
- areolar CT
- adipose CT
- smooth muscle
- skeletal muscle
- autonomic nervous
- somatic nervous

ciliated pseudostratified columnar

nose/pharynx/larynx/trachea/bronchus/bronchi 2/bronchi 3 {mucus secretion, traps foreign substances, propels substances out of system}

Simple squamous

lining lungs and alveoli/alveolus/respiratory bronchioles {gas exchange}

nonkeratinized stratified squamous

nose/mouth/pharynx/larynx {areas exposed to outside environment}

hyaline cartilage

trachea

elastic cartilage

epiglottis

autonomic nervous is what muscle?

smooth muscle

somatic nervous is what muscle?

skeletal muscle

major functions of system:

1. O2 & cO2 exchange {O2 delivery, CO2 removal: to/from blood}
2. acid-base regulation {i.e. blood pH}
3. Immune protection
4. Smell {olfaction: cranial nerve \#1}
5. Speech production {larynx and voice box}
6. thermoregulation {breath out relieves heat}
7. Warm/humidify inhaled air {necessary for alveoli gas exchange}
8. CV regulation {increase venous return w/increase ventilation/breathing: activation of proteins involved on BP regulation (ACE)}

Ventilation

movement of air in and out of the lungs

Respiration

gas exchange {O2 and CO2}

pulmonary ventilation

breathing {inhalation/inspiration: exhalation/expiration}

external respiration

exchange of gases between lungs and blood
{alveolar air sacs - pulmonary blood capillaries}

internal respiration

Exchange of gases between tissue cells of the body and the blood {systemic blood capillaries - Tissue cells}

cellular respiration

use of O2 w/in cells -\> ATP + CO2

structural classifications

- upper respiratory tract
- lower respiratory tract

Functional classifications

- conducting zone
- respiratory zone

upper respiratory tract

- nose
- mouth
- pharynx
- larynx

lower respiratory tract

- trachea
- bronchus 1
- bronchi 2
- bronchi 3
- bronchioles
- terminal bronchioles
- respiratory bronchioles
- alveolar duct
- alveolus w/alveoli sacs

conducting zone

- thicker epi
- goblet cells-\> mucus
- cilia
{bottom two: muco-ciliary clearance}

respiratory zone

- thinner epi
- type 1 & 2 alveolar cells
- immune protection {resident macrophages}

hyaline cartilage and smooth muscle trend throughout respiratory system

thicker cartilage and less smooth muscle in upper respiratory -\> little to no cartilage and more smooth muscle in lower respiratory

ciliated simple columnar

bronchioles

simple cuboidal

respiratory bronchioles

Cells of respiratory zone

- type 1 aveolar cells
- Respiratory membrane (aveolar epi. cells)
- type II aveolar cells
- macrophages

Type 1 Aveolar cells

simple squamous epi cells; make up wall of aveolus {site of gas exchange}

Respiratory cells

aveolar epi. cells + pulmonary capillary endothelial cells {simple squamous}
-\> fused basement membrane

Type II aveolar cells

*less numerous/scattered throughout that Type I*
- produce surfactant {helps lower surface tension}
-\> patency maintenance {keeping open}

Macrophages

reside in alveoli/immune protection

Lungs {basic Info}

- housed in thoracic cavity
\[clavicle, ribs, vertebrae, sternum]
- serious membrane
\[parietal pleura + serious fluid + visceral pleura]

Parietal Pleura

lines the walls of the thoracic cavity

Pleural cavity

intrapleural fluid between parietal pleura and visceral pleura {reduces friction}

Visceral Pleura

directly on the surface of the lungs {every crack/cannot be separated in lab}

Respiratory muscles

- Diaphragm
- external intercostals
- internal intercostals
- transverse abdominus
- sternocleidomastoid

Spirogram

the record of air volume and respiratory rate measured by the spirometer

Tidal Volume (Vt)

restful breathing range/amount of air per breath during restful breathing

Inspiratory reserve volume (IRV)

maximum inhale after normal inhale

Expiratory reserve volume (ERV)

maximum exhale after normal exhale

Residual Volume (RV)

what remains in the lungs after maximum exhale
*never able to fully empty the lungs*

Inspiratory capacity (IC)

{Vt + IRV}
maximum inhale after normal exhale

Functional residual capacity (FRC)

{ERV + RV}
amount in lungs after normal exhale

Vital capacity (VC)

{IRV + Vt + ERV}
Maximum exhale to maximum inhale

Total Lung Capacity (TLC)

maximum amount of air contained in lungs after a maximum inspiratory effort {total sum volume}

Capacities

- inspiratory
- functional residual
- vital
- total lung

Components of pulmonary ventilation

- minute ventilation
- tidal volume
- breathing frequency
- alveolar ventilation
- dead space volume

Minute ventilation (Ve)

amount of airflow in 1 minute
{Vt * Fb}

Breathing frequency (Fb)

respiratory rate

Alveolar ventilation

amount of "fresh air" reaching alveoli in 1 minute
{Ve - (Vd * Fb)}

Dead Space Volume (DSV)

amount of air in conducting zone

Boyle’s Law

pressure and volume are inversely related *pressure moves down a pressure gradient*

Atmospheric pressure (P atm)

at sea level 0mmHg

Alveolar Pressure (P alv)

0 mmHg

interpleural pressure (P ip)

The pressure within pleural cavity: -4 mmHg

* neg. value results in vacumm
* suction visceral pleura (on lung) to parietal pleura (on inside wall)
* if the size of thoracic cavity increase or decrease lungs with it
* airflow at FRC = 0

mechanisms of breathing

* inspiration
* expiration

inspiration \*restful breathing

1. neural input to skeletal muscles of inspiration
* phrenic nerve → diaphragm
* intercostals → external intercostals
2. contraction of inspiration muscles
* increase size of thoracic cavity
3. lungs expand
* increase alveolar volume
* decrease alveolar pressure
* P atm > P alv
4. Air moves down pressure gradient → lungs

\

Expiration \*restful breathing

1. withdrawal of neural input to inspiration muscle
2. relaxation of inspiration muscles
* decrease size of thoracic cavity
3. lungs recoil
* decrease alveolar volume
* increase alveolar pressure
* P atm < P alv
4. Air moves down pressure gradient → out of lungs

Factors Affecting Ventilation

1. increase surface tension = increase work of breathing {WOB}
* reduced by surfactant (produced by type II alveolar cells)
2. Lung Compliance {stretchability of lungs}
* increase of compliance = lungs + chest expand easily (dec. WOB)
* decrease of compliance = lungs + chest resist expansion (inc. WOB)
3. Airway Resistance
* change diameter via smooth mm of bronchioles = change in pressure/ resistance
* bronchodilation: increase diameter, increase airflow, decrease resistance

ex.) sympathetic NS - epinephrine
* bronchoconstriction: decrease diameter, increase resistance, decrease airflow

ex.) parasympathetic NS - histamine

partial pressure

the portion of pressure that an individual gas adds to the total pressure of a gas mixture

* calculated as a percentage of the total pressure in gas mixture

Nitrogon Partial Pressure

\~ 79% (600.4 mmHg)

Oxygen Partial Pressure

\~ 21% (160 mmHg)

Carbon Dioxide Partial Pressure

\~ .04% (0.3 mmHg)

Water Partial Pressure

\~ 0.3% (2.3 mmHg)

Atmospheric pressure

760 mmHg

Partial Pressures determine what?

the movement of CO2 and O2

What prevents alveolar collapse from water vapor?

secrete surfactant from Type II alveolar cells, break down water molecules/bonds

Gases move down what?

partial pressure gradient

inhalers have….

buteral, adrenergic receptors (agonist to receptors = bind and stimulate function)

Epipen

epinepherine (muscle relaxer), allergic reaction

Bronchodilation aspects

* high CO2 = dilation to exhale more CO2
* heat = metabolically active tissues produce heat

Atmospheric Air

* P O2 = 160 mmHg
* P CO2 = 0.3 mmHg

Alveolar Air

* P O2 = 105 mmHg
* P CO2 = 40 mmHg

“Deoxygenated” Blood

* P O2 = 40 mmHg
* P CO2 = 45 mmHg

Oxygenated Blood

* P O2 = 100 mmHg
* P CO2 = 40 mmHg

Tissue Cells Pressure

* P O2 = 40 mmHg
* P CO2 = 45 mmHg

Cellular Respiration

use of oxygen for energy source (ATP and heat, etc.)

Movement down partial pressure gradient is…

passive diffusion

majority of O2 transport as?

oxyhemoglobin - O2 bonded to hemoglobin (Hb)

saturation of hemoglobin in systemic arteriol blood

98%

Saturation of hemoglobin in systemic venous blood

75%

O2 transport

* small amount dissolved in plasma (1.5%)
* mainly transported bound to hemoglobin (98.5%)
* Hemoglobin
* 4 heme groups each containing iron (Fe) capable of binding O2
* binds easily in reversible reaction: Hb + O2 →

Sigmoidal Curve

1. once O2 molecules bind, easier for others to bind “positive cooperating”
2. less available sites as you reach 100% saturation

increased oxygen pressure means….

Hb binds large amounts of O2 pulmonary capillaries/systemic arterial blood

\
100mmHg \~ 100% saturation

Decreased oxygen pressure means….

Hb-O2 dissociation/ O2 unloads because Hb doesn’t hold on to O2 as much

\
→ tissue capillaries/ deoxygenated systemic venous blood

\
40mmHg \~ 75% saturation

Dissociation curve tells us…

how pressure of O2 effects the % saturation of Hb

Leftward Shift of Curve

* increased affinity for Hb to bind O2
* decrease unloading of O2
* increase loading of O2
* increase pH (low acidity)
* decreased temp.
* decrease Carbon Dioxide pressure

{LUNGS}

Rightward Shift

* decreased affinity for Hb bind O2
* increase unloading of O2
* decrease loading of O2
* decrease pH (increased acidity)
* increase temp.
* increase carbon dioxide pressure

{TISSUES}

CO2 Transport

* dissolved in plasma (7%)
* can bind to hemoglobin → carbaminohemoglobin {23%}
* majority tansported as HCO3- (bicarbonate} {70%}
* H2O + CO2 → carbonic anhydrous

CO2 at tissues

* CO2 moves down partial pressure gradient (tissues → blood)
* “Chloride shift” swaps HCO3- for Cl- to allow reaction to continue making HCO3-

CO2 at lungs

* CO2 moves down partial pressure gradient (blood → lungs)
* “reverse chloride shift” move HCO3- back into RBC to produce CO2 for exhalation

Control of Breathing components

* pontine respiratory group (PRG)
* medullary respiratory group (MRP)
* Dorsal respiratory group (DRG)
* Ventral respiratory group (VRG)
* Pre-botzinger complex (Pre-BotC)

PRG

* modifies
* coordinates
* smooth breathing pattern

Pre-BotC

* sets respiratory rhythm
* “automatic” nature of breathing (pacemaker cells)

VRG

* nerves of accessory muscles of inspiration → SCM (cranial nerve XI) & Scalenes = forced inhalation
* Intercostal N. + abdominal N.

→ internal intercostals & abdominal muscles = fixed exhalation

DRG

* Phrenic N. and Intercostal N.

I diaphragm I I ext. intercostals I

= rest breathing + forced inhalation

Chemoreceptors

homeostesis of P O2 & P CO2, H+ concentrations in the blood

Peripheral Chemoreceptors

* aortic bodies
* coratid bodies

Central Chemoreceptors

medulla oblongata

chemoreflex

* central integration w/in respiratory groups


* muscles of breathing and parameters of ventilation
* PO2 & PCO2 & H+ levels are brought back to homeostatic ranges

Chemoreflex pathway

* stimulus {Pressures of O2 and CO2 and H+ levels}
* afferent pathways - receptors {Peripheral/central}
* central integration {Pre-BotC/DRG/VRG}
* efferent pathway - effectors {muscles/ primary or accessory}
* change in ventilation {frequency of breathing or Tidal volume}
* change in Pressures of O2 and CO2 and H+ levels = negative feedback loop

Acid-Base regulation

* blood pH very tightly {7.35-7.45} avg. 7.4
* pH < 7.35 = acidosis → under neurofiring
* pH > 7.45 = alkolosis → hyper neurofiring
* regulated by
* buffering H+
* respiratory compensation
* renel compensation