Chapter 19

Respiratory

System

Respiration

Organs

Functions:

Works closely with circulatory system,

exchanging gases between air and blood:

Takes up oxygen from air and supplies it

to blood (for cellular respiration).

Removal and disposal of carbon dioxide

from blood (waste product from cellular

respiration).

Homeostatic Role:

Regulates blood pH.

Regulates blood oxygen and carbon dioxide

levels.

Functional Unit =

alveoliBlood transports gases

between lungs and tissues.

OrgansComponents:

Nasal cavity, throat (pharynx), larynx (voice box), trachea, bronchi, alveoli, and lungs.

Pathway of Inhaled Air:

Nasal cavity

Pharynx (Throat)

Larynx (Voice Box)

Trachea (Windpipe)

Bronchi

Bronchioles

Alveoli (Site of gas exchange)

Exhaled air follows reverse pathway.

The Respiratory Song

Nasal CavityPosterior to the external nose

Divided by a midline nasal septum

Posterior nasal apertures (choanae) open

into the nasal pharynx

Roof: ethmoid and sphenoid bones

Floor: hard and soft palates

Nasal Cavity - sinuses

Reduces weight of skull and are resonant chambers that affect sound.

Contains olfactory receptors for smell.

Warms and humidifies air before it enters lungs.

Pseudostratified ciliated epithelium

Increases surface area, goblet cells

produce mucous, cilia trap foreign

particles.

When sinuses swell, the mucous can’t drain, pressure increases, causes a

headache.

Membranes of the Nasal

Cavity

Nasal mucosa has many sensory nerve endings triggers the sneeze reflex

Tissue of this portion of the nose is heavily

saturated with capillaries (used to heat

inspired air in cooler temperatures)

This is why nosebleeds are common

Functions of the Nasal Mucosa

and Conchae

Lateral walls have projections called conchae that increase surface area

During inhalation, the conchae and nasal

mucosa

Filter, heat, and moisten air

During exhalation these structures

Reclaim heat and moisture

Pharynx Muscular tube that connects to the

Nasal cavity and mouth superiorly

Larynx and esophagus inferiorly

From the base of the skull to the level of the sixth

cervical vertebra (approx. 13cm or 5in.)

Larynx (Voicebox)

Attaches to the hyoid bone and opens into the

laryngopharynx

Continuous with the trachea

Made of eight rigid hyaline cartilages and a spoon-

shaped flap of elastic cartilage (epiglottis)

Functions

1. Provides a patent (open) airway

2. Routes air and food into proper channels

3. Voice production

Cartilages of the LarynxHyaline cartilage except for the epiglottis

Epiglottis: elastic cartilage; covers the laryngeal inlet during swallowing

Thyroid cartilage with laryngeal prominence (Adam’s apple)

More prominent in males due to growth stimulation during puberty

Vocal ligaments

Contain elastic fibers

Form core of vocal folds (true vocal cords)

Opening between them is the glottis

Folds vibrate to produce sound as air rushes up from the

lungs

Avascular (appear white)

Figure 22.5

(a) Vocal folds in closed position;

closed glottis

(b) Vocal folds in open position;

open glottis

Base of tongue

Epiglottis

Vestibular fold

(false vocal cord)

Vocal fold

(true vocal cord)

Glottis

Inner lining of trachea

Cuneiform cartilage

Corniculate cartilage

Voice Production Length and tension of cords change pitch

- Faster vibration = higher pitch

Male vocal cords become longer and thicker during puberty.

- slower vibration = lower pitch (voice deepening)

• Chambers of pharynx, oral, nasal, and sinus cavities amplify and enhance sound quality

• Sound is “shaped” into language by muscles of the pharynx, tongue, soft palate, and lips

Trachea (windpipe)

Walls are reinforced with C-

shaped hyaline cartilage

Connects larynx with bronchi

Lined with ciliated mucosa.

Beats continuously in the

opposite direction of

incoming air to expel mucus

loaded with dust and other

debris away from lungs

https://www.youtube.com/watch?v=NmHxhpMfD4c

Tracheostomy used to create an opening in the neck to bypass

an obstructed airway, clean or remove

secretions, to more easily, and usually more

safely, deliver oxygen to the lungs

Surgical Procedure

Landmarks

Primary Bronchio Formed by division of the trachea

o Enters the lung at the hilus (medial depression)

o Right bronchus is wider, shorter, and straighter than left

o Bronchi subdivide into smaller and smaller branches

Bronchi and BronchiolesPrimary bronchi

Secondary (lobar) bronchi

Tertiary (segmental) bronchi

Intralobular bronchioles (lobules)

Terminal bronchioles

Respiratory bronchioles

Alveolar ducts

Alveolar sacs

Alveoli

~300 million alveoli account for most

of the lungs’ volume and are the

main site for gas exchange

Macro

Micro

Coverings of the Lungs

Slide 13.13

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Pulmonary (visceral) pleura covers the lung surface

Parietal pleura lines the walls of the thoracic cavity

Pleural fluid fills the area between layers of pleura to allow gliding

Figure 22.8a

(a)

Alveolar duct

Alveolar ductAlveoli

Alveolar

sac

Respiratory

bronchioles

Terminal

bronchiole

Alveoli

Alveoli Surrounded by fine elastic fibers

Contain open pores that

Connect adjacent alveoli

Allow air pressure throughout the lung to be

equalized

House alveolar macrophages that keep alveolar

surfaces sterile

Gas Exchange

Slide 13.19

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

o Gas crosses the respiratory membrane by diffusion

oOxygen enters the blood

oCarbon dioxide enters the alveoli

Lungs

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Occupy most of the thoracic cavity

oApex is near the clavicle (superior portion)

oBase rests on the diaphragm (inferior portion)

Lobes of the Lungs

• Left lung is smaller, separated into two lobes by an

oblique fissure

• Right lung has three lobes separated by oblique and

horizontal fissures

• Lobules are the smallest subdivisions; served by

bronchioles and their branches

Most smokers and city dwellers have blackened

lobules due to carbon build up

Respiration Pulmonary ventilation (breathing):

movement of air into and outof the lungs

External respiration: O2 and CO2exchange between the lungsand the blood

Transport: O2 and CO2in the blood

Internal respiration: O2 and CO2exchange between systemic bloodvessels and tissues

Respiratory

system

Circulatory

system

Mechanics of Breathing

Pulmonary ventilation consists of two

phases

1. Inspiration: gases flow into the lungs

2. Expiration: gases exit the lungs

Figure 22.13 (1 of 2)

Sequence of events

Changes in anterior-

posterior and superior-

inferior dimensions

Changes in lateral

dimensions

(superior view)

Ribs are elevatedand sternum flares

as externalintercostals

contract.

Diaphragmmoves inferiorly

during contraction.

Externalintercostalscontract.

Inspiratory muscles contract (diaphragm descends; rib cage rises).

2

1

Thoracic cavity volume increases.

3 Lungs are stretched; intrapulmonary volume increases.

4 Intrapulmonary pressure drops (to –1 mm Hg).

5 Air (gases) flows into lungs down its pressure gradient until intrapulmonary pressure is 0 (equal to atmospheric pressure).

Figure 22.13 (2 of 2)

Sequence

of events

Changes in anterior-

posterior and superior-

inferior dimensions

Changes in

lateral dimensions

(superior view)

Ribs and sternumare depressed

as externalintercostals

relax.

Externalintercostalsrelax.

Diaphragmmovessuperiorlyas it relaxes.

1 Inspiratory muscles relax (diaphragm rises; rib cage descends due to recoil of costal cartilages).

2 Thoracic cavity volume decreases.

3 Elastic lungs recoil passively; intrapulmonary volume decreases.

4 Intrapulmonary pres-sure rises (to +1 mm Hg).

5 Air (gases) flows out of lungs down its pressure gradient until intra-pulmonary pressure is 0.

Pulmonary Function Tests

http://kidshealth.org/teen/diseases_conditions/allergies_immune/video_

spirometer.html

Spirometry

Disorders

Destruction

of capillaries

and alveoli

Thickening of bronchiole walls

and muscle causing narrowing.

Excess mucus blocks airway and causes infection and swelling.

Pneumonia

Respiratory Volumes and Capacities

Slide 13.26

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Normal breathing moves about 500 ml of air with each breath (tidal volume [TV])

Many factors that affect respiratory capacity

A person’s size

Sex

Age

Physical condition

Residual volume of air – after exhalation, about 1200 ml of air remains in the lungs

Respiratory Capacities

Slide 13.30

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 13.9

Respiratory Volumes and Capacities

Slide 13.28

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Vital capacity

The total amount of exchangeable air

Vital capacity = TV + IRV + ERV

Dead space volume

Air that remains in conducting zone and never reaches alveoli

About 150 ml

Respiratory Sounds

Slide 13.31

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Sounds are monitored with a stethoscope

Bronchial sounds – produced by air rushing through trachea and bronchi

Vesicular breathing sounds – soft sounds of air filling alveoli

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