Chapter 23: The Respiratory System Biol 141 A & P

mechanisms that use oxygen and produce carbon dioxide

surfaces of lungs
Is carried to cells by the cardiovascular system

3D Movie of Respiratory System

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area between air and circulating blood
Moves air to and from

the upper respiratory system, above the larynx, and the lower

terminal bronchioles
Consists of a respiratory portion:
the respiratory bronchioles and alveoli

The Respiratory Tract

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very thin (< 1 µm)
surface area must be very

of respiratory system

and bronchi:
contains mucous glands that secrete onto epithelial surface
In the

delicate, simple squamous epithelium
Contains scattered and specialized cells
Lines exchange surfaces

and other hazards?

mechanisms
Removes particles and pathogens
* Components of the Respiratory

nares
into nasal vestibule
Nasal hairs:
are in nasal vestibule
are the

right
Mucous secretions from paranasal sinus and tears:
clean and moisten the

meatuses
Meatuses
Constricted passageways that produce air turbulence:
warm and humidify incoming air
trap

cavities
Soft palate:
extends posterior to hard palate
divides superior nasopharynx from lower

Mucosa
Warm and humidify inhaled air for arrival at lower respiratory

systems
Extends from internal nares to entrances to larynx and esophagus
Nasopharynx
Oropharynx
Laryngopharynx

openings to left and right auditory tubes
The Oropharynx
Middle portion of

in normal breathing and production of sound?

larynx:
a cartilaginous structure that surrounds the glottis

thyroid cartilage
the cricoid cartilage
the epiglottis

cartilage
Forms anterior and lateral walls of larynx
Ligaments attach to hyoid

attach to first tracheal cartilage
Articulates with arytenoid cartilages
The Epiglottis
Composed of

entrance to trachea
During swallowing:
the larynx is elevated
the epiglottis folds back

the Larynx
arytenoid cartilages, corniculate cartilages
cuneiform cartilages

glottis
production of sound

cartilage and arytenoid cartilages
are covered by folds of laryngeal epithelium

Sound Variation
Sound is varied by:
tension on vocal folds: slender and

other structures

pharynx
intrinsic muscles that:
control vocal folds
open and close glottis
Coughing reflex: food

outside the lungs?

into mediastinum
where it branches into right and left pulmonary bronchi
The

trachea contacts esophagus
Ends of each tracheal cartilage are connected by:
an

ridge (the carina)
1) The Right Primary Bronchus
Is larger in diameter

along medial surface of the lung

vessels in hilus:
anchored to the mediastinum

left and right pleural cavities
The base:
inferior portion of each lung

1) The Right Lung- Has 3 lobes:
superior, middle,

longer
is displaced leftward by the heart forming the cardiac

branches
Extrapulmonary Bronchi
The left and right bronchi branches outside the lungs

(lobar bronchi)
1 secondary bronchus goes to each lobe

segmental bronchi
Each segmental bronchus:
supplies air to a single bronchopulmonary segment-
The

less cartilage and more smooth muscle
increasing muscular effects on airway

breathing difficulty

terminal bronchioles:
1 tertiary bronchus forms about 6500 terminal bronchioles

Autonomic Control
Regulates smooth muscle:
controls diameter of bronchioles
controls airflow and resistance

Bronchoconstriction
Constricts bronchi
Caused

the smallest trabecular partitions (interlobular septa)

Each terminal bronchiole delivers

respiratory bronchioles, where gas exchange takes place

ducts
Alveolar ducts end at alveolar sacs:
common chambers connected to

fibers
Alveolar Epithelium
Consists

do not produce enough surfactant

exchange takes place
3 Parts of the

alveoli
compromises function of respiratory membrane

a venule
respiratory exchange surfaces receive blood:
from arteries of pulmonary circuit
a

oxygen and nutrients to tissues of conducting passageways of lung

vessels are easily blocked by blood clots, fat, or air

mediastinum
Each pleural cavity:
holds a lung
is lined with a serous

in exchanging O2 and CO2 with the environment

Internal respiration-

and capillaries
Transport of O2 and CO2:
between alveolar capillaries
between capillary beds

lungs?

of respiratory tract
Provides alveolar ventilation
InterActive Physiology: Respiratory System: Anatomy Review:

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important physiological effects

P = 1/V
In a contained gas:
external pressure forces molecules closer

area of higher pressure to area of lower pressure

Respiration
Causes volume changes that create changes in pressure
Volume

greater force
High compliance requires less force
Factors

be measured inside or outside the lungs
Normal atmospheric pressure:
1

breathing, the difference between Patm and intrapulmonary pressure is small:
about

range:
from —30 mm Hg to +100 mm Hg

Averages —4 mm Hg
Maximum of —18 mm Hg
Remains below Patm

pump:
which aids in venous return to heart
Tidal Volume
Amount of air

a collapsed lung
result of pneumothorax

responsible for respiratory movements?

muscles of the ribs
accessory respiratory muscles:
activated when respiration increases significantly

of normal air movement
External intracostal muscles:
assist inhalation
25% of normal air

the ribs
Abdominal muscles:
compress the abdomen
force diaphragm upward

quiet breathing and forced breathing

or deep breathing:
is dominated by diaphragm
Costal breathing or shallow

by accessory muscles
Maximum levels occur in exhaustion

by varying:
the number of breaths per minute (respiratory rate)
the volume

rate  tidal volume
Measures pulmonary ventilation
Anatomic

volume — anatomic dead space  respiratory rate
Alveoli contain less

given respiratory rate:
increasing tidal volume increases alveolar ventilation rate
for a

volumes and capacities useful in diagnosis
Pulmonary Function Tests
Measure rates and

reserve volume (ERV):
after a normal exhalation
Residual volume:
after maximal exhalation
minimal volume

reserve volume
Functional residual capacity (FRC):
expiratory reserve volume + residual

on:
partial pressures of the gases
diffusion of molecules between gas and

InterActive Physiology: Respiratory System: Gas Exchange

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diffusion depends on physical principles, or gas laws
e.g., Boyle’s law

(H2O) about 0.5%
Carbon dioxide (CO2) about 0.04%

into each other
Each gas contributes to the total pressure:
in proportion

atmosphere
All partial pressures together add up to 760 mm Hg

liquid:
gas dissolves in liquid until equilibrium is reached
At a given

a gas in solution (at given partial pressure and temperature)

gases across the respiratory membrane determine different partial pressures and

the respiratory membrane
– distances involved in gas exchange are small
O2 and

and Partial Pressures in Respiration
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Normal Partial Pressures
In pulmonary vein plasma:
PCO2

PCO2
The concentration gradient causes:
O2 to enter blood
CO2 to leave

from conducting passageways
Lowers the PO2 of blood entering systemic

gradient in peripheral capillaries is opposite of lungs:
CO2 diffuses into

blood? What is the structure and function of hemoglobin?

CO2 to meet physiological needs

a reversible reaction
Each RBC has about 280 million Hb molecules:
each

Respiration: Oxygen and Carbon Dioxide Transport

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Blood pH, Temperature
Metabolic activity within RBCs

to partial pressure of oxygen:
higher PO2 results in greater Hb

PO2)
Amount of O2 released depends on interstitial PO2
Up to

7.4, 37°C)
When pH drops or temperature rises:
more oxygen is released
curve

curve
Caused by CO2:
CO2 diffuses into RBC
an enzyme, called carbonic anhydrase,

BPG
BPG directly affects O2 binding and release:
more BPG, more

of adult Hb
At the same PO2:
fetal Hb binds more O2

to low O2 partial pressure in surrounding plasma
If PO2 increases,

Transport
Figure 23–23 (Navigator)
Respiration: Carbon Dioxide and Oxygen Exchange
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InterActive Physiology: Respiratory

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metabolism (cellular respiration)
CO2

(H2CO3):
which dissociates into H+ and bicarbonate (HCO3—)
23% is bound to

which form through dissociation of carbonic acid produced by carbonic

at peripheral and alveolar capillaries maintain balance by:
changes in blood

tissues and pickup at lungs are regulated by:
rising PCO2 levels:
relaxes

respiratory rates increase under neural control
Have both voluntary and involuntary

oblongata
motor neurons that control respiratory muscles
The Respiratory Centers
3 pairs of

of respiration
Can be divided into 2 groups:
Dorsal respiratory group (DRG)-
Inspiratory

become inactive:
allowing passive exhalation

muscles
After inhalation:
expiratory center neurons stimulate active exhalation

that adjust output of respiratory rhythmicity centers:
regulating respiratory rate and

basic pace and depth of respiration
The pneumotaxic center:
modifies the pace

reflex pattern
May result from connection problems between pacemaker complex and

PO2, or pH
of blood or cerebrospinal fluid
Baroreceptors in aortic

in lung volume
Irritating physical or chemical stimuli:
in nasal cavity,

cranial nerve IX -The glossopharyngeal nerve:
from carotid bodies
stimulated by changes

in the medulla oblongata:
to restore homeostasis
Hypoventilation- A common cause of

centers
When blood pressure falls:
respiration increases
When blood pressure increases:
respiration decreases

when lungs are exposed to:
toxic vapors
chemicals irritants
mechanical stimulation
Cause sneezing, coughing,

to clear airways:
sneezing and coughing

in hypothalamus
2. Temporarily closes airway:
to prevent foreign substances from entering
Anticipation

centers in the pons and medulla oblongata, and modified in

are collapsed
lungs contain no air
During delivery:
placental connection is lost
blood PO2

at first breath:
pulls blood into pulmonary circulation
closing foramen ovale and

lung compliance
lowering vital capacity
Arthritic changes:
restrict chest movements
limit respiratory minute volume
Emphysema:
affects

peripheral tissues requires coordination between several systems:
particularly the respiratory

controlling lung perfusion
Increases respiratory drive:
through chemoreceptor stimulation
Raises cardiac output and

exchange between air and circulating blood
moving air to and from

system:
the nose and nasal cavity
the pharynx
Structures and functions of the

surfaces, the bronchi
the bronchioles, alveoli and alveolar ducts
blood supply to

and delivery:
partial pressure
oxygen transport (RBCs and hemoglobin)
carbon dioxide transport
Control of