Human Anatomy & Physiology



Basic Anatomy & Physiology II Dr. L. Bacha

Chapter Outline (Marieb & Hoehn 6th ed)

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( what is the major function of the respiratory system?

( cellular respiration is the actual use and production of what?

- it is the cornerstone of what?

( because it moves air, what is the respiratory system also involved in?

( the upper respiratory system includes the nose, pharynx and associated structures

( the lower respiratory system includes the larynx, trachea, bronchi, and lungs

21.1 The upper respiratory system warms, humidifies, and filters air

The Nose and Paranasal Sinuses

( read about the five important functions of the nose

Nasal Cavity

( the internal part of the nose is the nasal cavity

( FEATURES OF THE NASAL CAVITY:

1. during breathing, air enters the nasal cavity by passing through what structures?

2. the nasal cavity is divided by what midline structure?

- the nasal septum is formed by cartilage anteriorly (toward the tip of the nose) and bone posteriorly

3. the floor of the nasal cavity is formed by the hard palate, which separates the nasal cavity above from the oral cavity below

4. olfactory epithelium lies in the superior region of the nasal cavity and contains

receptors for the sense of smell

5. the respiratory mucosa is the mucous membrane that lines most of the nasal cavity (and other parts of the respiratory system, such as the trachea); it consists of:

- a ciliated pseudostratified columnar epithelium with goblet cells that produce mucus

- underlying connective tissue called the lamina propria, that is well vascularized

( functions of the respiratory mucosa:

a. filters the air

- air is filtered as particles (dust, pollen, bacteria, etc.) become trapped in the sticky blanket of mucus that covers the cilia of the epithelium

- the cilia sweep the mucus with trapped particles toward the pharynx, where it is swallowed

b. warms the air

- air is warmed as heat radiates from the numerous blood vessels in the lamina propria

c. moistens the air

- air is moistened as water evaporates from mucus made by goblet cells and other glands

6. name and describe the nasal conchae, which protrude medially from each lateral wall of the nasal cavity:

( what is the groove inferior to each nasal concha called?

( the nasal conchae and meatuses increase the surface area of the mucous membrane, and force the air to swirl around, which increases contact of the air with the mucous membrane

7. nasolacrimal ducts empty into the inferior nasal meatus of the nasal cavity

- do you remember what secretion the nasolacrimal ducts carry?

Paranasal Sinuses

( sinuses are air-filled cavities lined with mucous membrane present in some of the bones of the skull; they surround and open into the nasal cavity

( list the bones of the skull that contain paranasal sinuses:

( the paranasal sinuses act as resonating chambers for sound; what are the other functions of the paranasal sinuses?

The Pharynx

( what is the shape of the pharynx?

( what is the pharynx commonly called?

( list the three regions of the pharynx and locate them on Fig. 21.4 (a):

The Nasopharynx

◦ the nasopharynx is the superior portion of the pharynx that extends from the nasal cavity to the uvula (free tip of the soft palate); even easier, think of the nasopharynx as the area superior to the soft palate

◦ is the nasopharynx a passageway for air, food, or both?

◦ during swallowing, the soft palate and uvula move superiorly, which is an action that does what?

◦ name the tonsil that the nasopharynx contains in its posterior wall:

◦ the pharyngotympanic tubes (auditory tubes; Eustachian tubes) connect the nasopharynx to the cavity of the middle ear and allow air to equalize pressure in the cavity of the middle ear with the outside atmosphere

The Oropharynx

◦ the oropharynx lies posterior to the oral cavity; it extends inferiorly from what to what?

◦ is it a passageway for air, food, or both?

◦ name the tonsils that it contains:

The Laryngopharynx

◦ extends from the tip of the epiglottis to the openings of the larynx and esophagus

◦ is it a passageway for air, food, or both?

21.2 The lower respiratory system consists of conducting & respiratory zone structures

( respiratory zone consists of structures in the lungs having alveoli where gas exchange occur

( conducting zone consists of the remaining passageways where gas exchange does not occur

Larynx

Basic Anatomy

( what is the other name for the larynx?

( list the three functions of the larynx:

( the framework of the larynx is composed of 9 cartilages, some of which are listed here:

( thyroid cartilage - large, anterior shield-shaped piece

( cricoid cartilage

- ring like piece of cartilage inferior to the thyroid cartilage

- it serves as a landmark for making an emergency airway (a tracheotomy)

( arytenoid cartilages

- what do they anchor?

( epiglottis

- a large, leaf-shaped piece of elastic cartilage covered by mucous membrane

- during swallowing, the pharynx and larynx rise; elevation of the larynx causes the epiglottis to tip down and cover the glottis

- define glottis (( from the glossary in the back of the book):

( there are two pairs of folds of mucous membrane in the larynx:

1. the vocal folds (true vocal cords) contain numerous elastic fibers

- as air rushes up from the lungs, the vocal folds vibrate, producing what?

2. the superior pair, the vestibular folds, (false vocal cords)

- what do they help to close?

Voice Production

( if air is directed against the vocal folds, they vibrate and produce sound

- muscles within the larynx contract to change the length and tension of the vocal folds

- the tenser the vocal folds, the faster they vibrate and the higher the pitch

- what does loudness of the voice depend on?

Sphincter Functions of the Larynx

- read the paragraph on sphincter functions on p. 713

The Trachea

( the trachea is a passageway for air; what is the other name for the trachea?

( the trachea is lined by the respiratory mucosa like that of the nasal cavity:

- ciliated, pseudostratified columnar epithelium with goblet cells and underlying, well-vascularized connective tissue

( the wall of the trachea contains 16 - 20 C-shaped pieces of hyaline cartilages

- what are the functions of the cartilage “rings”?

- the gaps in the cartilage abut the esophagus and allow the it to expand during swallowing

The Bronchi and Subdivisions

Examine Fig. 21.8 to 21.9

The air passageways in the lungs branch and branch again, about 23 times overall, in a pattern often called what?

The Bronchial Tree: (I have summarized the information from pages 714 to 715 here:)

1. the distal part of the trachea divides into a right main (primary bronchus) and

a left main (primary) bronchus (plural is “bronchi”); each main bronchus

enters a lung and branches into lobes of the lung as lobar (secondary) bronchi

- how does the right main bronchus differ from the left (see the second column on p. 714)?

- what is the consequence of this?

2. lobar (secondary) bronchi

- each lobar bronchus branches within a lobe of a lung into segmental (tertiary) bronchi

3. segmental (tertiary) bronchi

- each supplies a unit within a lobe called a bronchopulmonary segment (Fig. 21.12) and eventually branches into bronchioles

- read about bronchopulmonary segments in the upper right column of page 717

4. bronchioles

- bronchioles branch many times within a lobe of the lung

5. eventually, bronchioles lead into passageways with alveoli, and finally into alveolar sacs, which are formed entirely by clusters of alveoli

( Respiratory Zone Structures (page 715)

- the respiratory zone is defined by the presence of alveoli, the sites of gas exchange

Alveoli

- an alveolus (pleural is “alveoli”) is a thin walled sac-like structure; about how many alveoli are in the lungs?!

- the outer surfaces of alveoli are closely associated with numerous pulmonary capillaries

- alveoli are surrounded by elastic fibers and are connected by open alveolar pores. These allow air pressure throughout the lung to be equalized and provide alternate air routes to any alveoli whose bronchi have collapsed due to disease

The Respiratory Membrane

( gas exchange occurs in the lungs across the very thin (0.5 um) respiratory membrane, between air in the alveoli and blood in pulmonary capillaries

( the four components of the respiratory membrane are:

(1) type I alveolar cells (the simple squamous epithelial cells that line the alveolus)

(2) the basement membrane of the alveolus

(3) the basement membrane of the pulmonary capillary

(4) the endothelium of the pulmonary capillary

Alveoli Three major types of cells are found in alveoli:

⦁ Type I alveolar cells – already described above

⦁ Type II alveolar cells

- cuboidal cells scattered among the more numerous type I alveolar cells

- the type II alveolar cells secrete alveolar fluid that contains a detergent-like substance called what?

( surfactant decreases surface tension so that the alveoli don’t collapse

⦁ Alveolar macrophages

- crawl freely along the internal alveolar surfaces and phagocytize bacteria, dust, etc.

21.3 Each multilobed lung occupies its own pleural cavity

( the lungs are paired organs in the thoracic cavity that are made up of the components of the bronchial tree

Gross Anatomy of the Lungs

( the lungs are highly distensible and highly elastic

( define the following terms pertaining to the lungs:

costal surface

apex

base

hilum

root of the lung - is formed by the structures that enter and leave the lungs through the hilum, including pulmonary arteries and veins, main bronchi, lymphatic vessels, nerves, etc.

( the lungs are divided into lobes separated by CT filled spaces called fissures

( list the lobes of the left lung (from Fig. 21.11 (a):

( list the lobes of the right lung (from Fig. 21.11 (a): :

( each lobe is subdivided into bronchopulmonary segments (see Fig. 21.12); each segment is served by what and receives what?

- please read about why are the bronchopulmonary segments are clinically important and what their connective tissue partitions allow!

Blood Supply and Innervation of the Lungs

Pulmonary Circulation of the Lungs

( in the pulmonary circuit, blood flows from the right ventricle ( pulmonary arteries ( pulmonary capillary networks closely surrounding the alveoli of the lungs ( pulmonary veins ( left atrium ( left ventricle

- do pulmonary arteries carry oxygenated or deoxygenated blood?

- do pulmonary veins carry oxygenated or deoxygenated blood?

Bronchial (Systemic) Circulation of the Lungs

( name the arteries that provide oxygenated systemic blood to the lung tissues:

( what vessel do the bronchial arteries arise from:

( in the bronchial (systemic) circuit, blood flows from the left ventricle ( aorta ( bronchial arteries ( systemic capillaries in the lungs ( bronchial veins ( right atrium ( right ventricle

Innervation of the Lungs

( the lungs are innervated by the sympathetic and parasympathetic neurons

- parasympathetic fibers cause air passageways to do what?

- sympathetic fibers cause air passageways to do what?

The Pleurae

( the pleurae consist of a double-layer of serous membranes (serosa) of the thoracic cavity

( name the two layers that form the pleurae and indicate what each layer covers:

( define pleural cavity (( from the glossary in the back of the book):

( pleural fluid – a thin film of serous fluid in the pleural cavity secreted by the serous membranes (the pleurae)

( functions of pleural fluid:

(1) reduces friction between the serous membranes, so that the lungs can slide easily over the thorax wall during breathing movements

(2) increases surface tension and causes the parietal pleura and visceral pleurae to adhere to each other!

So, the lungs (covered by the visceral pleura) cling tightly to the thoracic wall and to the cranial surface of the diaphragm (which are covered by the parietal pleura). As the volume of the thoracic cavity increases during inspiration, the lungs expand along with it!

- so, can the pleurae slide easily across each other?

- can the pleurae normally separate from each other?

21.4 Volume changes cause pressure changes, which cause air to move

Pressure Relationships in the Thoracic Cavity

( define Atmospheric Pressure

- what is the value of atmospheric pressure at sea level?

Intrapulmonary Pressure

∙ define intrapulmonary (intra-alveolar) pressure:

∙ it rises and falls with the phases of breathing; it varies from 762 mm Hg (during expiration) to 758 mm Hg (during inspiration)

Intrapleural Pressure

∙ define intrapleural pressure:

∙ it varies from 754 mm Hg (during inspiration) to 756 mm Hg (during expiration)

- so, how does it compare to the other two pressures (atmospheric and intrapulmonary)?

∙ read about intrapleural pressure in the bottom of the first column on page 720

Pulmonary Ventilation

( pulmonary ventilation (breathing), consisting of inspiration (inhalation) and expiration (exhalation), is a mechanical process that depends on what?

( a rule to keep in mind is what?

Inspiration

Inspiration is said to be active because it involves muscle contractions; quiet (unforced) Inspiration involves contraction of two inspiratory muscles, the diaphragm and external intercostal muscles:

( action of the diaphragm

( what happens to the dome-shaped diaphragm when it contracts?

( as a result, what happens to the height (length) of the thoracic cavity?

( the diaphragm is the most important muscle in producing volume changes that lead to normal quiet inspiration

( action of the external intercostal muscles

( contraction of the external intercostals raises the ribs and draws them together, which increases the diameter of the thoracic cavity

Expiration

( in healthy individuals, why is quiet expiration in healthy individuals said to be a passive process?

( ( ( ( ( My Summary of the Events in Pulmonary Ventilation ( ( ( ( (

1. AT THE END OF EXPIRATION AND BEFORE THE NEXT INSPIRATION

Atmospheric pressure (760 mmHg) is equal to intrapulmonary pressure (760 mmHg), and there is no net movement of air.

2. INSPIRATION

Nerve impulses are conducted from the respiratory center

in the medulla of the brain to motor neurons in the spinal cord

( (

impulses via phrenic nerves impulses via intercostal nerves

( (

Contraction of the diaphragm Contraction of external intercostal muscles

( (

Diaphragm lowers Rib cage raises and rotates

( (

Length of thoracic cavity increases Diameter of thoracic cavity increases

( (

VOLUME of the THORACIC CAVITY INCREASES

(

( as the thoracic cavity expands, the LUNGS EXPAND and the

INTRAPULMONARY VOLUME INCREASES

(

INTRAPULMONARY PRESSURE DECREASES (to 758 mmHg) and

is LOWER THAN ATMOSPHERIC PRESSURE (760 mmHg)

(

AIR FLOWS INTO the ALVEOLI of the lungs from the atmosphere

At the end of inspiration, the intrapulmonary pressure becomes equal to atmospheric pressure (760 mmHg), and there is no net movement of air.

Inspiration is an active process, because it involves muscle contraction. Deep inspiration (forced inspiration) involves additional muscles to further increase the size of the thoracic cavity. This causes a greater difference between intrapulmonary pressure and atmospheric pressure, so that more air flows into the lungs.

( The lungs expand (are distended) as the volume of the thoracic cavity increases because:

1. they adhere to the thoracic wall due to surface tension between the parietal pleura and visceral pleura

2. a decrease in intrapleural pressure (from 756 to 750 mmHg) causes the alveoli to expand

3. EXPIRATION

the respiratory center in the medulla oblongata of the brain stops initiating impulses to the inspiratory muscles, so that the diaphragm and external intercostal muscles stop contracting

( (

Relaxation of diaphragm Relaxation of external intercostals

( (

Diaphragm raises Rib cage lowers

(back to resting position) (back to resting position)

( (

Length of thoracic cavity decreases Diameter of thoracic cavity decreases

to original length to original diameter

( (

VOLUME of the THORACIC CAVITY DECREASES (back to original volume)

(

( THE LUNGS DECREASE to ORIGINAL SIZE and INTRAPULMONARY VOLUME DECREASES

due to elastic recoil of the lungs

(

INTRAPULMONARY PRESSURE INCREASES (to 762 mmHg)

and is GREATER THAN ATMOSPHERIC PRESSURE (760 mmHg)

(

AIR FLOWS OUT of the ALVEOLI of the lungs to the atmosphere

At the end of expiration, the alveolar pressure becomes equal to atmospheric

pressure (760 mmHg), and there is no net movement of air.

Normal expiration is a passive process, because it does not involve muscle contraction.

Deep or forced expiration is an active process that involves the contraction of additional muscles to further decrease the size of the thoracic cavity. This causes a greater difference between intrapulmonary pressure and atmospheric pressure, so that more air flows out of the lungs.

( The lungs do not collapse completely during expiration because:

1. Surfactant, which is produced by type II alveolar cells (septal cells) decreases the surface tension of the alveoli.

2. The lungs are kept slightly inflated because of the negative intrapleural pressure. (Remember the intrapleural pressure is always less than the intrapulmonary pressure and atmospheric pressure.)

( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (

Physical Factors Influencing Pulmonary Ventilation (on page 723)

Energy is used for inspiratory muscles to contract and enlarge the thorax.

Energy is also used to overcome three factors that hinder air passage and pulmonary ventilation: airway resistance, alveolar surface tension, and lung compliance

Airway Resistance

( the major nonelastic source of resistance to gas flow is what?

( ( airway diameter ( ( resistance ( ( air flow

Alveolar Surface Tension

( read about surface tension and surfactant

( as a result of the action of surfactant in the alveoli, is surface tension of alveolar fluid increased or decreased?

- is more or less energy needed to expand the lungs?

Lung Compliance

( the lungs have high lung compliance, which means they are very stretchy or distensible

( read about the conditions that can diminish lung compliance

21.5 Measuring respiratory volumes, capacities, and flow rates helps us assess ventilation

( the original clinical measuring device, used to measure lung volumes and capacities, is called what?

Respiratory Volumes

( the normal respiration rate (= the number of breaths taken each minute)

of a healthy adult at rest is about 12 breaths per minute

( To define the following four terms, see the column called “Description” in Figure 21.18 on p. 726!

( describe tidal volume (TV):

( a normal tidal volume is how many milliliters?

( describe inspiratory reserve volume (IRV):

( if you inhale normally, then force in as much air as you can, (try it!) the volume that you forcefully inhaled is the inspiratory reserve volume!

( describe expiratory reserve volume (ERV):

( if you exhale normally, then force out as much air as you can, the volume that you forcefully exhaled is the expiratory reserve volume!

( define residual volume (RV):

( so, do the lungs empty of air after you exhale as much as you can?!

Dead Space

( the conducting airways, which contain air that does not take part in gas exchange, form the anatomic dead space

( what is the typical volume of air in the anatomic dead space?

Alveolar Ventilation

( define minute ventilation:

- we will write an equation that shows its relation to tidal volume and respiration rate:

- during vigorous exercise, what can the minute ventilation reach?

21.6 Gas exchange by diffusion between the blood, lungs, and tissues

Basic Properties of Gases

Dalton’s Law of Partial Pressures

• what does Dalton’s law of partial pressures state?

- what is the pressure exerted by each gas called?

- each gas in a mixture of gases will diffuse across a permeable membrane from an area of high to low partial pressure of that gas

External Respiration = Pulmonary Gas Exchange

( during external respiration, gas exchange occurs between air in the alveoli and blood in the pulmonary capillaries

Internal Respiration = Systemic Gas Exchange

( during internal respiration, gas exchange occurs between the blood in

systemic capillaries and the cells of tissues throughout the body

( we will do a drawing in class to cover pulmonary and systemic gas exchange!

21.7 Oxygen is transported by hemoglobin, and carbon dioxide is transported in 3ways

Oxygen Transport

( molecular oxygen is carried in blood in what two ways?

( oxygen is poorly soluble in water, so only about what percent of the oxygen transported in the blood is dissolved in the plasma?

( 98.5% of the oxygen that is carried in the blood is bound to the iron of the heme units of hemoglobin within RBCs

( examine what is shown in reference to O2 (with red arrows) in Fig. 21.23 (a and b) on p. 735

Association of Oxygen and Hemoglobin

( write the single reversible equation (shown on page 731) that describes the loading and unloading of oxygen:

( define a partially saturated hemoglobin molecule:

( define a fully saturated hemoglobin molecule:

( the rate at which hemoglobin reversibly binds or releases O2 is regulated by PO2; temperature, blood pH, and PCO2

- these factors interact to ensure what?

Influence of P02 on Hemoglobin Saturation

( what does the oxygen-hemoglobin dissociation curve show?

( this curve is not so bad, if you think about this…the more oxygen in the blood (higher PO2), the more O2 will be bound to hemoglobin (the more saturated it will be with O2)

-conversely, with less O2 in the blood (lower PO2), hemoglobin will be less saturated with O2

( examine the curve in Focus Fig. 22.1 on page 732 and note that:

( when PO2 is high (100 mm Hg), hemoglobin binds with large amounts of O2 and is almost 100% saturated (in systemic arteries and pulmonary veins)

( when PO2 is low (40 mm Hg), hemoglobin binds with less O2 and is about 75% saturated with O2 (in systemic veins and pulmonary arteries)

Influence of Other Factors on Hemoglobin Saturation

∙ temperature, blood pH, and PCO2 influence hemoglobin saturation at a given PO2:

- all of these factors influence hemoglobin saturation by modifying hemoglobin’s three-dimensional structure, thereby changing its affinity for O2

- an increase in temperature, PCO2, and H+ levels in blood does what?

- conversely, a decrease in any of these factors does what?

- please read the next few paragraphs in the middle of the first column on page 734 (beginning with “If you give a little thought…”) to help you understand how these factors affect hemoglobin saturation and oxygen unloading

Carbon Dioxide Transport

( Normally active body cells produce about 200 ml of CO2 each minute – exactly the amount excreted by the lungs!

( Carbon dioxide is transported in the blood from the tissue cells to the lungs in three forms; list the numbered headings printed in bold print on page 735 - 736:

1.

( what percent of CO2 is simply dissolved in the plasma as CO2?

2.

( what percent of CO2 is bound to hemoglobin?

( the CO2 is bound to the amino acids of the protein part (globin part) of hemoglobin in RBCs and is called carbaminohemoglobin

- write the equation that shows this:

3.

( what percent of the CO2 transported in the blood is carried in the plasma as bicarbonate ions?

- write the equation that shows this:

( observe what is shown in reference to CO2 (with blue arrows) in Fig. 22.23 (a and b) on p 735

21.8 Respiratory centers in the brain stem control breathing with input from chemoreceptors and higher brain centers

( the nervous system controls respiration automatically to

meet the body’s metabolic demands without your conscious concern

Neural Mechanisms

( the respiratory center of the medulla oblongata and pons controls nerve impulses to the diaphragm and external intercostal muscles to initiate inspiration

Factors Influencing Breathing Rate and Depth

Factors that influence the respiratory center to alter the rate and depth of respiration are:

1. Chemical factors

◦ we have chemoreceptors sensitive to PO2, PCO2, and pH of arterial blood; they are most sensitive to PCO2!

2. Higher brain centers

◦ Hypothalamic Controls – strong emotions, pain, body temperature changes, and other stressors can alter respiration by acting through the hypothalamus

◦ Cortical Controls – although the brain stem respiratory centers normally regulate breathing involuntarily, we can also exert conscious (voluntary) control over the rate and depth of breathing, which involves the cerebral cortex

3. Inflation reflex (Hering-Breuer reflex)

◦ a protective reflex initiated by extreme overinflation of the lungs

( define the following terms (( from the glossary in the back of the book!):

hypercapnia:

hypocapnia:

hyperventilation:

apnea:

hypoxia:

-----------------------

PART I

As you study the organs and their specific parts, see the Figures in the textbook and see Table 21.1 and Table 21.2 for a nice summary.

structure of bronchi vs. bronchioles:

( bronchi - have an epithelium, bundles of smooth muscle and plates of hyaline cartilage; are larger in diameter

( bronchioles - have an epithelium, bundles of smooth muscle; no hyaline cartilage

Time out for …AN OVERVIEW OF THE PROCESS OF RESPIRATION: three basic steps:

1. pulmonary ventilation (breathing) = inspiration (inhalation) and expiration (exhalation) of air between the atmosphere and the alveoli of the lungs

2. external respiration (pulmonary gas exchange) = the exchange of gases across the respiratory membrane between the air in the alveoli of the lungs and the blood in pulmonary capillaries

3. internal respiration (systemic gas exchange) = the exchange of gases between blood in systemic capillaries and the cells of tissues throughout the body

PART 2

( time out for Boyle’s Law:

the pressure of a gas in a closed container varies inversely with the volume of the container

(at a constant temperature); this means that:

◦ if the volume of a chamber decreases, pressure of the gas inside increases or decreases?

◦ if the volume of a chamber increases, pressure of the gas inside increases or decreases?

HOMEOSTATIC IMBALANCE 21.8 (on page 724)

( during an acute asthma attack, histamine and other inflammatory chemicals that are released can cause what?

( what are the effects of epinephrine released during sympathetic nervous system activation on the diameter of bronchioles and airway resistance?

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( I have summarized here what you should know about control of respiration; too much detail in the book…!

more CO2

is exhaled

impulses to Respiratory Center, which

sends impulses to muscles of

inspiration to increase depth

and rate of pulmonary ventilation

stimulates

chemoreceptors

in aortic bodies

and carotid bodies

e.g. hypoventilation

causes (PCO2

(hypercapnia)

in arterial blood

which causes (H+

The end!

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