Anatomy ch 23

Ventilation

physical movement of air

inspiration (inhalation)

expiration (exhalation)

external respiration

gas exchange at lungs

internal respiration

gas exchange at tissues

Upper Respiratory System

Nose

nasal cavity

pharynx

associated structures

Lower respiratory system

larynx

trachea

bronchi

lungs

Conducting Zone

tubes and interconnecting cavities that filter, warm, moisten air

Respiratory Zone

tubes and tissues within lungs where gas exchange occurs

Nose

external portion is cartilage and skin

lined with mucous membrane

bony framework formed by frontal, nasal, maxillary bones

Nasal cavity

paranasal duct

nasolacrimal duct

respiratory region

olfactory region

paranasal ducts

drain mucus

nasolacrimal ducts

drain tears

respiratory region

larger, inferior

respiratory epithelium (mucus secreting)

olfactory region

smaller, superior

olfactory receptor cells

cilia, no goblet cells (bc if there were the mucus would block smell)

pharynx

* passageway for air and food
* provides a resonating chamber for speech sounds
* houses the tonsils - which participate in immunological reactions against foreign invaders

nasopharynx

back of nasal caivty

5 openings: 2 internal nares, 2 that lead to auditory tubes, 1 leads to oropharynx

ciliated pseudostratified columnar

oropharynx

back of oral cavity

fauces - one arched opening at back of mouth

nonkeratinized stratified squamous

laryngoharynx

beginning of throat

starts at hyoid

both respiratory and digestive tubes

nonkeratinized stratified squamous

pharyngeal tonsils

adnoids

nasopharynx

palatine tonsils

either side of the back of oral cavity

say ahh

oropharynx

lingual tonsils

behind tongue

oropharynx

larynx

rises when we swallow, causes epiglottis to fold down over flottis

thryoid cartilage

Adam’s apple

epiglottis

elastic cartilage; covers opening to trachea when swallowing

glottis

has vocal folds; true vocal cords

cricoid cartilage

landmarked used for tracehtomy

trachea

* anterior to esophagus
* from larynx to superior border of T5 (branches into L&R primary bronchi)
* 16-20 incomplete C0shaped rings of hyalin cartilage

Bronchi

* superior border of T5 (L&R bronchi)
* continue to branch
* terminal bronchioles

R primary bronchi

more vertical, shorter, wider than L

carina

internal ridge where bronchi split

important reference point in chest iagin

terminal bronchioles

end of conducting zone

bronchial tree

trachea → main bronchi → lobar bronchi → segmental bronchi → bronchioles → terminal bronchioles

Lungs

pleural membrane

* parietal pleura
* pleural cavity
* visceral pleura

Alveoli

* conducting zone ends at terminal bronchioles, then respiratory zone begins at respiratory bronchioles
* respiratory zone terminates at alveoli (air sacs found within the lungs)

microscopic airways

respiratory bronchioles → alveolar ducts → alveolar sacs → alveoli

alveolar sac

cluster of grapes

alveolus

individual grape

Type I alveolar cells

simple squamous

line walls

main sites of gas exchange

Type II alveolar cells

rounded or cuboidal epithelial cells

beween Type I; microvilli

secrete alveolar fluid (surfactant)

Surfactant

lowers the surface tension of alveolar fluid → lowers tendency to collapse

mixture of phospholipids and lipoproteins

patency

open; free of obstruction

alveolar wall

Type I and II alveolar cells and associated alveolar macrophages

Respiratory membrane

1. alveolar wall
2. epithelial basement membrane
3. capillary basement membrane (often fused to the epithelial basement membrane)
4. capillary endothelium

Vestibule

nonkeratinized stratified squamous epithelium

no cilia

no goblet cells

contains numerous hairs

respiratory region

pseudostratified ciliated columnar epithelium

cilia

goblet cells

contains conchae and meatuses

olfactory region

olfactory epithelium

cilia

no goblet cells

functions in olfaction

nasopharynx

pseudostratified ciliated columnar epithelium

cilia

goblet cells

passageway for air; contains internal nares, opening for auditory tubes, and pharyngeal tonsil

oropharynx

nonkeratinized stratified squamous epithelium

no cilia

no goblet cells

passageway for both air and food and drink; contains opening from mouth (fauces)

Laryngopharynx

nonkeratinized stratified squamous epithelium

no cilia

no goblet cells

passageway for both air and food and drink

larynx above vocal folds

nonkeratinized stratified squamous epithelium

no cilia

no goblet cells

passageway for air; contains vocal folds for voice production

larynx below vocal folds

pseudostratified ciliated columnar epithelium below the vocal folds

cilia

goblet cells

passageway for air; contains C-shaped rings of cartilage to keep trachea open

all bronchi

pseudostratified ciliated columnar epithelium

cilia

goblet cells

passageway for air; contain plates of C-shaped rings of cartilage to maintain patency

larger bronchioles

ciliated simple columnar epithelium

cilia

goblet cells

passageway for air; contain more smooth muscle than in the bronchi

smaller bronchioles

ciliated simple columnar epithelium

cilia

no goblet cells

passageway for air; contain more smooth muscle than in the larger bronchioles

terminal bronchioles

nonciliated simple columnar epithelium

no cilia

no goblet cells

passageway for air; contain more smooth muscle than in the smaller bronchioles

respiratory bronchioles

simple cuboidal to simple squamous epithelium

no cilia

no goblet cells

passageway for air; gas exchange

alveolar ducts and alveoli

simple squamous epithelium

no cilia

no goblet cells

passageway for air; gas exchange; produce surfactant

pulmonary ventilation

air flows between atmosphere and alveoli due to alternating pressure differences created by contraction and relaxation of respiratory muscles

Boyl’s Law

the pressure and volume of a gas have an inverse relationship (V increase P decrease)

Surface tension of alveolar fluid

inwardly directed force in the alveolu which must be overcome to expand the lungs during each inspration

complaince

how much effort it takes to stretch the lungs and the chest walla

airway resistance

rate of airflow depends on pressure differences and airway resistance

diameter of bronchioles changes

eupnea

normal quiet breathing

apnea

temporary cessation/stopping of breathing

dyspnea

difficult or labored breathing

tachypnea

abnormally rapid breathingc

costal breathing

shallow chest breathing

diaphragmatic breathing

deep breathing

coughing

a long-drawn and deep inhalation followed by a complete closure of the rima glottidis, which results in a strong exhalation that suddenly pushes the rima glottidis open and sends a blast of air through the upper respiratory passages. stimulus for this reflex act may be a foreign body lodged in the larynx, trachea, or epiglottis

sneezing

spasmodic contraction of muscles of exhalation that forcefully expels air through the nose and mouth stimulus may be an irritation of the nasal mucosa

sighing

a long-drawn and deep inhalation immediately followed by a shorter but forceful exhalation

yawning

a deep inhalation through the widely opened mouth producing an exaggerated depression of the mandible. it may be stimulated y drowsiness, or someone else’s yawning, but the precise cause is unknown

sobbing

a series of convulsive inhalations followed by a single exhalation. the rima glottidis closes earlier than normal after each inhalation so only a little air enters the lungs with each inhalation

crying

an inhalation followed by many short convulsive exhalations, during which the rima glottidis remains open and the vocal folds vibrate; accompanies by characteristic facial expressions and tears

laughing

the same basic movements as crying, but the movements and the facial expressions usually differ from those of crying. Laughing and crying are sometimes indistinguishable

hiccupping

spasmodic contraction of the diaphragm followed by a spasmodic close of the rima glottidis, which produces a sharp sound on inhalation. stimulus is usually irritation of the sensory nerve endings of the GI tract

valsalva maneuver

forced exhalation against a closed rima glottidis as may occur during periods of straining while defecating

pressurizing the middle ear

the nose and mouth are held closed and air from the lungs is forced through the auditory tube into the middle ear. employed by those snorkeling or scuba dicing during descent to equalize the pressure of the middle ear with that of the external environment

Dalton’s Law

* each gas in a mixture of gasses exerts its own pressure as if it no other gases were present
* partial pressures determine movement of O2 and CO2 between atmosphere/lungs, lungs/blood, blood/body cells

Henry’s Law

the quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility

External Respiration

* O2 diffused from alveoli into blood
* CO2 diffused from blood into alveoli
* gases diffuse from areas of higher partial pressure to areas of lower partial pressure

Internal respiration

* O2 diffused from blood to body cells
* CO2 diffused from body cells to blood

Normal quiet inhalation

DRG active 2 seconds

Diaphragm contracts and external intercostal muscles contract during their most active phase

normal quiet exhaltion

DRG inactive 3 seconds

diaphragm relaxes and external intercostal muscles become less active and relax, followed by elastic recoil of lungs

forceful inhalation

DRG activates VRG

diaphragm contracts and external intercostal muscles contract during their most active stage

accessory muscles of inhalation contract

accessory muscles of inhalation

sternocleidomastoid

scalenes

pectoralis minor muscles

forceful exhalation

VRG

accessory muscles of exhalation contract

accessory muscles of exhalation

internal intercostal

external abdominal oblique

internal abdominal oblique

transversus abdominus

rectus abdominus

Dorsal Respiratory Group

DRG

inspiratory area

Ventral Respiratory Group

VRG

expiratory area

Pre-Botzinger complex and neurons

Pre-Botzinger complex

cluster of neurons

set basic rhythm of breathing (may control impulse rate of DRG - they’re always in communication)

remaining neurons

forceful breathing

activated by VRG and DRG

send impulses to inhalation and accessory muscles (sternocleidomastoid, scalenes, pectoralis minor)

Medullary Respiratory Group

Forceful exhalation DRG (inactive) VRG forceful inhalation neurons (inactive)

VRG neurons involved → nerve impulses to exhalation accessory muscles (internal intercostals, external/internal obliques, transverse/rectus abdominis)

Pontine Respiratory Group

PRG

penumotaxic area

collection of neurons in pons

active during inhalation and exhalation

transmit impulses to DRG

may modify rhythm generated by VRG (exercising, speaking, sleeping)

cortical influences

allow conscious control of respiration that may be needed to avoid inhaling noxious gases or water

chemoreceptor

central and peripheral chemoreceptors monitor levels of O2 and CO2 and provide input to the respiratory center

Central chemoreceptors

CNS

in or near medulla oblongata

H+ concentration, PCO2, or both in CSF

peripheral chemoreceptors

aortic bodies

carotid bodies

P O2, H+, P CO2 in blood

hypercapnia

* slight increase in Pco2 (and H+)
* stimulates central chemoreceptors
* DRG increases breathing rate
* CO2 increase

Hypocapnia

* arterial Pco2 lower than 40 mmHG
* no stimulation of chemoreceptors
* DRG sets moderate pace
* CO2 drops