Chapt19 Respiratory System

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Chapter 19

Lecture

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Hole’s Human Anatomy

and PhysiologyTwelfth Edition

Shier w Butler w Lewis

Chapter

19

Respiratory System


4

19.1: Introduction

• The respiratory system consists of passages that filter

incoming air and transport it into the body, into the lungs, and

to the many microscopic air sacs where gases are exchanged

• Respiration is the process of exchanging gases between the

atmosphere and body cells

• It consists of the following events:

• Ventilation

• External respiration

• Transport of gases

• Internal respiration

• Cellular respiration

5

19.2: Why We Breathe

• Respiration occurs on a macroscopic level at the organ

system

• Gas exchange, oxygen and carbon dioxide, occur at the

cellular and molecular levels

•Aerobic reactions of cellular respiration allow for:

•ATP production

• Carbon dioxide generation forming carbonic acid

19.3: Organs of the

Respiratory System

• The organs of the respiratory

system can be divided into two

tracts:

• Upper respiratory tract

• The nose

• Nasal cavity

• Sinuses

• Pharynx

• Lower respiratory tract

• Larynx

• Trachea

• Bronchial tree

• Lungs


Larynx

Bronchus

Nostril

Right lung Left lung

Soft palate

Pharynx

Epiglottis

Esophagus

Frontal

sinus

Nasal

cavity

Hard

palate

Oral

cavity

Trachea

6

7

Nose

Frontal sinus

Nostril

Hard palate

Uvula

EpiglottisHyoid bone

Larynx

Superior

Middle

Inferior

Sphenoidal sinus

Pharyngeal tonsil

Nasopharynx

Palatine tonsilOropharynxLingual tonsil

Laryngopharynx

Esophagus

Tongue

Trachea

Nasal

conchae

Opening of

auditory tube


8

Nasal Cavity


Mucus Particle

Goblet cell

CiliaNasal cavity

Epithelial cell

(b)(a)

b: © Biophoto Associates/Photo Researchers, Inc.

9

Sinuses

• The sinuses are air-filled spaces

in the maxillary, frontal, ethmoid,

and sphenoid bones of the skull

10

19.1 Clinical Application

The Effects of Cigarette Smoking on

the Respiratory System

11

Pharynx• The pharynx is posterior to the oral cavity and between the nasal

cavity and the larynxCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Frontal sinus

Nostril

Hard palate

Uvula

Epiglottis

Hyoid bone

Larynx

Superior

Middle

Inferior

Sphenoidal sinus

Pharyngeal tonsil

Nasopharynx

Palatine tonsil

Oropharynx

Lingual tonsil

Laryngopharynx

Esophagus

Tongue

Trachea

Nasal

conchae

Opening of

auditory tube

12

Larynx

• The larynx is an enlargement in the

airway superior to the trachea and

inferior to the pharynx

• It is composed of a framework of

muscles and cartilages bound by

elastic tissueEpiglottic cartilage

Hyoid bone

Thyroid cartilage

Cricoid cartilage

Hyoid bone

Epiglottic cartilage

Thyroid cartilage

Cricoid cartilage

(b)

(a)


Trachea

Trachea

False vocal cord

Glottis

Epiglottis

Hyoid bone

Thyroid cartilage

Cricoid cartilage

Hyoid bone

Epiglottis

Thyroid cartilage

Cricoid cartilage

(b)

(a)

False vocal

cord

True vocal

cord

Thyroid cartilage

Cuneiform cartilage

Corniculate cartilage

Arytenoid cartilage

True vocal cord


Glottis

Corniculate cartilage

(a)

(b)

Epiglottis

Glottis

(c)

Posterior portion

of tongueFalse vocal cord

True vocal cord

Cuneiform cartilage

Inner lining of trachea

c: © CNRI/PhotoTake


Trachea

• The trachea (windpipe) is a

flexible cylindrical tube about

2.5 centimeters in diameter

and 12.5 centimeters in length

•As it extends downward

anterior to the esophagus and

into the thoracic cavity, it

splits into the right and left

primary bronchi


Larynx

Carina

Trachea

Superior (upper)

lobe bronchus

Right primary

bronchus

Middle lobe

bronchus

Inferior (lower)

lobe bronchi

Thyroid

cartilage

Cricoid

cartilage

Cartilaginous

ring

Left

primary

bronchus

Superior (upper)

lobe bronchus

13

14

Hyaline cartilage

Ciliated epithelium

Smooth muscle

Lumen of trachea

Connective tissue



Connective

tissue

Hyaline

cartilage

Ciliated

epithelium

Lumen of

trachea

Smooth

muscle

© Ed Reschke

Thyroid gland

Incision

Trachea

Hyoid

bone

Thyroid

cartilage

Cricoid

cartilage

Jugular

notch


Bronchial Tree

• The bronchial tree

consists of branched

airways leading from

the trachea to the

microscopic air sacs in

the lungs


Larynx

Right middle lobe

Right superior (upper) lobe

Right primary bronchus

Secondary bronchus

Right inferior (lower) lobe

Alveolar duct

Alveolus

Respiratory bronchiole

Tertiary bronchus

Terminal bronchiole

Trachea

Left superior

(upper) lobe

Left inferior

(lower) lobe

15

Branches of the Bronchial Tree

16

• The successive divisions of

the branches from the trachea

to the alveoli are:

1. Right and left primary

bronchi

2. Secondary or lobar

bronchi

3. Tertiary or segmental

bronchi

4. Intralobular bronchioles

5. Terminal bronchioles

6. Respiratory bronchioles

7. Alveolar ducts

8. Alveolar sacs

9. Alveoli


© Ralph Hutchings/Visuals Unlimited

17


Intralobular bronchiole

Blood flow

Alveolus

Smooth muscle

Alveoli

Blood flow

Blood flow

Pulmonary

artery

Pulmonary

vein

Terminal

bronchiole

Respiratory

bronchiole

Pulmonary

arteriole

Pulmonary

venule

Capillary network on

surface of alveolus

Alveolar

duct

Alveolar

sac


Capillary

Alveolus

Simple squamous

epithelial cells

© McGraw-Hill Higher Education, Inc./Bob Coyle

The Respiratory Tubes

18

• The structure of the bronchus is

similar to that of the trachea, but

the C-shaped cartilaginous rings

are replaced with cartilaginous

plates where the bronchus enters

the lung

• These respiratory tubes become

thinner and thinner, and the cell

layers thin and change until the

alveoli is reached

• It is the alveoli that provides

surface area for gas exchange


Blood flow

Blood flow

Arteriole

Alveolus

Capillary

Air

O2CO2

CO2

Alveolar

wall

Venule

O2

19


Blood vessel Capillary Alveolus

Tissues and Organs: A Text-Atlas of Scanning Electron Microscopy, by R.G. Kessel and

R.H. Kardon. © 1979 W.H. Freeman and Company


Courtesy of the American Lung Association

Bronchiole

Alveolus

20

Lungs

• The right and left lungs are soft, spongy, cone-shaped organs

in the thoracic cavity

• The right lung has three lobes and the left lung two lobes

Thyroid cartilage

Cricoid cartilage

Clavicle

Scapula

Rib cartilage

Sternum

Superior (upper)

lobe of right lung

Middle lobe

of right lung

Inferior (lower)

lobe of right lung

Superior (upper)

lobe of left lung

Inferior (lower)

lobe of left lung

Trachea

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Right lung

Heart

Left lung

Pericardium

Pleura

Plane of

section

Pericardial

cavity

Right pleural

cavity

Visceral

pleura

Parietal

pleura

Left pleural

cavity

21

22


Lung Irritants

23

19.4: Breathing Mechanism

• Breathing or ventilation is the movement of air from outside

of the body into the bronchial tree and the alveoli

• The actions responsible for these air movements are

inspiration, or inhalation, and expiration, or exhalation

24

Inspiration

• Atmospheric pressure due to

the weight of the air is the

force that moves air into the

lungs

• At sea level, atmospheric

pressure is 760 millimeters of

mercury (mm Hg)

• Moving the plunger of a

syringe causes air to move in

or out

• Air movements in and out of

the lungs occur in much the

same way


Diaphragm

Air passageway

Atmospheric pressure

of 760 mm Hg on the

outside

Atmospheric

pressure

of 760 mm Hg

on the inside


(a) (b)

25

• Intra-alveolar pressure decreases to about 758mm Hg as the

thoracic cavity enlarges due to diaphragm downward

movement caused by impulses carried by the phrenic nerves

• Atmospheric pressure then forces air into the airways

Inspiration


Diaphragm

(a) (b)

Intra-alveolar

pressure

(760 mm Hg)

Atmospheric pressure

(760 mm Hg)

Intra-alveolar

pressure

(758 mm Hg)

26


(a) (b)

External

intercostal

muscles pull

ribs up and out

Diaphragm

contracts

Sternum

moves

Up and out

Sternocleidomastoid

elevates sternum

Pectoralis minor

elevates ribs

Diaphragm

contracts more

Inspiration

27

28

Expiration

• The forces responsible for normal resting expiration come

from elastic recoil of lung tissues and from surface tension

• These factors increase the intra-alveolar pressure about 1 mm

Hg above atmospheric pressure forcing air out of the lungs

29

ExpirationCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Diaphragm

Diaphragm

(a) (b)

Abdominal organs

recoil and press

diaphragm upward

Posterior internal

intercostal muscles

pull ribs down and

inward

Abdominal organs

force diaphragm

higher

Abdominal wall

muscles contract

and compress

abdominal organs

30

31

Respiratory Air

Volumes and Capacities

• Different degrees of effort in breathing move different

volumes of air in and out of the lungs

• This measurement of volumes is called spirometryCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Lu

ng

vo

lum

e i

n m

illi

lite

rs (

mL

)

6,000

5,000

4,000

3,000

2,000

1,000

0

Inspiratory

reserve volume

Tidal

volume

Residual

volume

Expiratory

reserve volume

Vital

capacityInspiratory

capacity

Total lung

capacity

Functional

residual

capacity

32

33

Alveolar Ventilation

• The volume of new atmospheric air moved into the

respiratory passages each minute is minute ventilation

• It equals the tidal volume multiplied by the breathing rate

• Much of the new air remains in the physiologic dead space

• The tidal volume minus the physiologic dead space then

multiplied by breathing rate is the alveolar ventilation rate

• This is the volume of air that reaches the alveoli

• This impacts the concentrations of oxygen and carbon

dioxide in the alveoli

34

Nonrespiratory Air Movements

•Air movements other than breathing are called

nonrespiratory movements

• They clear air passages, as in coughing and sneezing, or

express emotions, as in laughing and crying

35

36


Respiratory Disorders That

Decrease Ventilation: Bronchial

Asthma and Emphysema

37

19.5: Control of Breathing

• Normal breathing is a rhythmic, involuntary act that

continues when a person is unconscious

• Respiratory muscles can be controlled as well voluntarily

38

Respiratory Areas

• Groups of neurons in the

brainstem comprise the respiratory

areas that control breathing

• Impulses travel on cranial nerves

and spinal nerves, causing

inspiration and expiration

• Respiratory areas also adjust the

rate and depth of breathing

• The respiratory areas include:

• Respiratory center of the

medulla

• Respiratory group of the

pons


Diaphragm

Medulla oblongata

Pons

Midbrain

Dorsal respiratory group

Pontine respiratory

group

Ventral respiratory group

Fourth

ventricle

Medullary

respiratory

center

Internal (expiratory)

intercostal muscles

External (inspiratory)

intercostal muscles

39

Respiratory muscles

Forceful breathing

Nerve impulses Nerve impulses

Pontine respiratory

group

Ventral

respiratory

group

Dorsal

respiratory

group

Medullary respiratory center

Respiratory areas

Basic rhythm

of breathing


40

Factors Affecting Breathing

•A number of factors affect

breathing rate and depth

including:

• Partial pressure of

oxygen (Po2)

• Partial pressure of carbon

dioxide (Pco2)

• Degree of stretch of lung

tissue

• Emotional state

• Level of physical activity

• Receptors involved include

mechanoreceptors and central

and peripheral chemoreceptors

Carotid bodies

Aorta

Heart

Aortic bodies

Medulla oblongata

Sensory nerve

(branch of

glossopharyngeal

nerve)

Common carotid

artery

Sensory nerve

(branch of vagus nerve)


41

Factors Affecting Breathing

• Changes in blood pH, O2 and

CO2 concentration stimulates

chemoreceptors

• Motor impulses can travel

from the respiratory center

to the diaphragm and external

intercostal muscles

• Contraction of these muscles

causes the lungs to expand

stimulating mechanoreceptors in

the lungs

• Inhibitory impulses from the

mechanoreceptors back to the

respiratory center prevent

overinflation of the lungs


Respiratory center

Motor pathways

Spinal cord

Intercostal nerve

Rib

Diaphragm

Sensory pathway

Phrenic nerve

Stretch receptors

Lung

External intercostal

muscles

Vagus nerve

––

42

43


Exercise and Breathing

44

19.6: Alveolar Gas Exchanges

• The alveoli are the sites of the vital process of gas exchange

between the air and the blood

45

AlveoliCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Courtesy of the American Lung Association

46

Capillary lumen

Alveolus

Macrophage

Capillary

Alveolus

Red blood cell

Diffusion of CO2

Diffusion of O2

Capillary endothelium

Interstitial space

Alveolar epithelium

Type I

(squamous

epithelial) cell

of alveolar wall

Type II

(surfactant-

secreting) cell

Fluid with

surfactant

Respiratory

membrane Cell of

capillary wall

Alveolar fluid

(with surfactant)

Basement membrane of

alveolar epithelium

Basement membrane of

capillary endothelium

Respiratory

membrane


47

Respiratory Membrane

• Part of the wall of an alveolus is made up of cells (type II

cells) that secrete pulmonary surfactant

• The bulk of the wall of an alveolus consists of a layer of

simple squamous epithelium (type I cells)

• Both of these layers make up the respiratory membrane

through which gas exchange takes place

48


AS

AS

BM

IS

RBC

EP

© Imagingbody.com

49

AlveolusDiffusion of CO2

Diffusion of O2

Capillary

Alveolar

wall

Blood flow

(from body

tissues)

Blood flow

(to body

tissues)

PCO2 = 45 mm Hg


PCO2 = 40 mm Hg

PO2 = 40 mm Hg

PO2 = 104 mm Hg

PO2 = 104 mm Hg

PCO2 = 40 mm Hg

50

Diffusion Through the

Respiratory Membrane• Molecules diffuse from regions where they are in higher

concentration toward regions where they are in lower

concentration

• It is important to know the concentration gradient

• In respiration, think in terms of gas partial pressures

• Gases diffuse from areas of higher partial pressure to areas of

lower partial pressure

• The respiratory membrane is normally thin and gas exchange

is rapid

• Increased diffusion is favored with more surface area,

shorter distance, greater solubility of gases and a steeper

partial pressure gradient

• Decreased diffusion occurs from decreased surface area

51


Effects of High Altitude

52


Disorders That Impair Gas Exchange:

Pneumonia, Tuberculosis, and Adult

Respiratory Distress Syndrome

53

19.7: Gas Transport

• Blood transports O2 and CO2 between the lungs and the

body cells

•As the gases enter the blood, they dissolve in the plasma or

chemically combine with other atoms or molecules

54

Oxygen Transport

• Almost all oxygen carried in the blood is bound to the protein

hemoglobin in the form of oxyhemoglobin

• Chemical bonds between O2 and hemoglobin are relatively

unstable

• Oxyhemoglobin releases O2 into the body cells

• About 75% of the O2 remains bound to hemoglobin in the

venous blood ensuring safe CO2 levels and thereby pH

55

AlveolusCapillary

2

2

2

(a) (b)

Blood flow

(from body

tissues)

Alveolar

wallOxygen

molecules

Hemoglobin

molecules

Diffusion

of oxygen

Oxyhemoglobin

molecule

Hemoglobin

molecules

Diffusion

of oxygen

Blood flow

(to lungs)

Blood

PO = 40 mm HgBlood

PO = 95 mm Hg

Tissue cells

Tissue

PO = 40 mm Hg


56


10

20

30

40

50

60

70

80

90

100

Oxyhemoglobin dissociation at 38°C

% s

atu

rati

on

of

he

mo

glo

bin

100 40 50 60 70 9080 100 110 120 130 14020 30

PO2(mm Hg)

57

• The amount of oxygen released from oxyhemoglobin increases with: Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

10

20

30

40

50

60

70

80

90

100

% s

atu

rati

on

of

he

mo

glo

bin

100 40 50 60 70 9080 100 110 120 130 14020 30


20 mm Hg

40 mm Hg

80 mm Hg

PCO2=

PO2(mm Hg)


10

20

30

40

50

60

70

80

90

100


% s

atu

rati

on

of

he

mo

glo

bin

100 40 50 60 70 9080 100 110 120 130 14020 30

7.6

7.4

7.2

pH =

PO2(mm Hg)

10

20

30

40

50

60

70

80

90

100

% s

atu

rati

on

of

he

mo

glo

bin

100 40 50 60 70 9080 100 110 120 130 14020 30

PO2(mm Hg)

Oxyhemoglobin dissociation at various temperatures


57

58

Carbon Dioxide Transport

• Blood flowing through capillaries gains CO2 because the

tissues have a high Pco2

• The CO2 is transported to the lungs in one of three forms:

• As CO2 dissolved in plasma

• As part of a compound with hemoglobin

• As part of a bicarbonate ion

59

Tissue cell

Cellular CO2

Plasma Red blood cell Capillary wall

Bloodflow tosystemicvenule

Tissue

PCO2= 45 mm Hg


CO2 dissolved

in plasma

PCO2 = 40 mm Hg

Blood

flow from

systemic

arteriole

CO2 combined with

hemoglobin to form

carbaminohemoglobin

H2CO3

H+combines

with hemoglobin

PCO2= 45 mm HgHCO3

- + H+

CO2 + H2O

HCO3-

60

HCO3-

Red blood cell

HCO3-

Cl-

Cl-

Cl-

HCO3-

PlasmaCapillary wall


61

CO2CO2

Alveolus

Alveolar wall

Capillary wall

CO2

HCO3-

Carbaminohemoglobin

Plasma Red blood cell

PCO2= 45 mm Hg

PCO2= 40 mm Hg

CO2

CO2dissolved

in plasma

Blood flow

from pulmonary

arteriole

HCO3-+ H+

H2CO3

H+ released

from hemoglobin

Blood

flow to

pulmonary

venule

PCO2= 40 mm Hg

+ H2O

CO2 + hemoglobin


62

63

19.8: Lifespan Changes

• Lifespan changes reflect an accumulation of environmental

influences and the effects of aging in other organ systems,

and may include:

• The cilia become less active

• Mucous thickening

• Swallowing, gagging, and coughing reflexes slowing

• Macrophages in the lungs lose efficiency

• An increased susceptibility to respiratory infections

• A “barrel chest” may develop

• Bronchial walls thin and collapse

• Dead space increasing

64

Important Points in Chapter 19:

Outcomes to be Assessed

19.1: Introduction

Identify the general functions of the respiratory system.

19.2: Why We Breathe

Explain why respiration is necessary for cellular survival.

19.3: Organs of the Respiratory System

Name and describe the locations of the organs of the respiratory

system.

Describe the functions of each organ of the respiratory system.

19.4: Breathing Mechanism

Explain how inspiration and expiration are accomplished.

Name and define each of the respiratory air volumes and capacities.

65



Calculate the alveolar ventilation rate.

List several non-respiratory air movements and explain how each

occurs.

19.5: Control of Breathing

Locate the respiratory areas and explain control of normal breathing.

Discuss how various factors affect breathing.

19.6: Alveolar Gas Exchanges

Define partial pressure and explain its importance in diffusion of

gases.

Describe gas exchange in the pulmonary and systemic circuits.

66



Describe the structure and function of the respiratory membrane.

19.7: Gas Transport

Explain how the blood transports oxygen and carbon dioxide.

19.8: Lifespan Changes

Describe the effects of aging on the respiratory system.

67

Quiz 19

Complete Quiz 19 now!

Read Chapter 20.

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Chapt19 Respiratory System