summer studying lecture 14 respiratory system

What are the two tracts of the respiratory system?

1. Upper respiratory tract

2. Lower respiratory tract

What is the upper respiratory tract?

1. Nose

2. Nasal cavity

3. Sinuses

4. Pharynx

5. Larynx

What is the lower respiratory tract?

1. Trachea

2. Bronchial tree

3. Lungs

What are the properties of the nose?

Consists of nostrils and nasal cavity

What are the nostrils (external nares)?

Provide openings for air to enter and leave nasal cavity

• openings are protected from particles by internal hairs

What is the nasal cavity?

Hollow spaces behind nose that’s separated by the nasal septum (L/R)

1. Conchae separate nasal cavity into meat uses

2. Upper portion contains olfactory receptors for sense of smell

3. Lined w/ mucous membrane (pseudostratified ciliated epithelium)

What are the properties of the mucous membrane?

1. Goblet cells produce mucus→ traps dust and pathogens

2. Cilia sweep mucus toward pharynx, where it is swallowed

3. Pathogens and particles are destroyed in stomach to prevent infection

What are sinuses (paranasal sinuses)?

Air-filled spacesin the maxillary, frontal, ethmoid, nd sphenoid bones of the skull

• open into nasal cavity

• mucous membrane continuously lines the lining of the nasal cavitty

• reduces weight of skull

• resonates voice

What is sinusitis?

Due to infection or allergic reaction

• may result in blockage of sinus drainage, causing sinus pressure and headache

What is the effect of cigarette smoking on the respiratory system?

Damage from smoking is slow, progressive, and deadly

• smoking slows and paralyzes cilia→ dirt and pathogens can no longer be removed from the respiratory system

What is smoker’s cough?

Occurs when cilia no longer function→ excess mucus is produced, and mucus must be coughed up

• pathogens can now access respiratory surfaces, causing infections

• coughing leads to chronic bronchitis

• bronchial thickening results in difficulty w/ expiration

• alveolar walls are destroyed, leading to emphysema

• abnomal cells may start dividing and replacing ciliated cells

What is the rate of smoking to lung cancer?

20% of smokers will develop lung cancer

• every 15 cigarettes smoked, a DNA mutation will occur (99.9% of muttations are repaired)

What is the pharynx?

Space posterior to nasal cavity, oral cavity, and larynx

• passageway for food and air

• aids in sound production

• consists of nasopharnyx, oropharynx, laryngopharynx

What are the 3 parts of the pharynx?

1. nasopharynx

2. oropharynx

3. laryngnopharynx

What is the nasopharynx?

superior to soft palate; air passage

• conteains openings to auditory tubes

What is the oropharynx?

Posterior to mouth, inferior to nasopharynx

• passageway for food and air

What is the laryngopharynx?

inferior to oropharynx

• continuous w/ larynx and esophagus

What is the larynx?

An enlargement in the airway superior to trachea; anterior and slightly inferior to laryngopharynx

• moves air in and out of trachea

• houses vocal cords

• commpsoed of a framework of muscles and cartilages bound by elastic tissue

• consists of 3 large single cartilages

What are the 3 single cartilages of the larynx?

1. thyroid

2. cricoid

3. epiglottic

What is the thyroid (Adam’s apple)?

largest cartilage; thyroid gland covers lower part

What is the cricoid?

below thyroid cartilage

What is the epiglottic?

central portion of flap-like epiglottis

What are the 3 pairs of small cartilages in the larynx?

1. arytenoid

2. corniculate

3. cuneiform

What are the false vocal cords?

Upper (vestibular) folds

• do not produce vocal sounds

• help close airway during swallowing

What are the true vocal cords?

lower folds

• produce vocal sounds

• sound created as air is forced between them, vibrating them

• true vocal cords+opening between them is called “glottis”

What is the trachea (windpipe)?

Flexible cylindrical tube (2.5cm in diameter, 12.5cm in length)

• extends downward anterior to the esophagus

• as it entes thoracci cavity, splits into L/R primary brnochi

• lined w/ ciliated mucous membrane w/ goblet cells

• contains 20 C-shaped rings of hyaline cartilage to prevent collaspse of trachea

What is a tracheostomy?

A procedure that cuts an opening in the trachea, to insert a tube for air exchange

• usually done when an object is lodged in the larynx or trachea

What are the properties of the bronchial tree?

Consists of branched airway leading from the trachea to the microscopic air sacs in the lungs

• starts w/ trachea, branching airways resemble an upside-down tree

What are the parts of the bronchial tree?

1. R/L primary bronchi

2. lobar (secondary) bronchi

3. segmental (tertiary) bronchi

4. intralobular bronchioles

5. terminal bronchioles

6. respiratory bronchioles

7. alveolar ducts

8. alveolar sacs

9. alveoli

what are the main (primary) bronchi?

branch from trachea

• consists of right/left, eah leading to a lung

What are the lobar (secondary) bronchi?

branch from main bronchi

• 2 on left, 3 on right

What are the segmental (tertiary) bronchi?

each enters a segment

• 8 on left, 10 on right

What are the intralobular bronchioles?

Each enters a lobule

What are the terminal bronchioles?

40-80 in each lobule

What are the respiratory bronchioles?

first structures to conduct gas exchange

• alveoli bud from sides of their walls

What are the alveolar ducts?

branches of respiratory bronchioles

What are the alveolar sacs?

outpouchings of alveolar ducts

What are the alveoli?

microscopic air sacs that perform gas exchange; open into sacs

What is the structure of the main bronchi?

Similar to trachea, but contains cartilaginous plates (no C-ring)

• as bronchi continue to branch→ becomes narrower, less cartilage

• cartilage disappears in bronchioles; allows changes in diameter (bronchodilation and bronchoconstriction)

• smooth muscle becomes more prominent, then diminishes from bronchioles to alveolar ducts (disappears)

What epithelium is in larger respiratory tubes?

Pseudostratified ciliated columnar epithelium

What epithelium is in respiratory bronchioles?

simple cuboidal epithelium

What epithelium is in alveoli?

Simple squamous epithelium

What are the functions of the respiratory tubes and alveoli?

1. branches of bronchial tree transport air

2. alveoli provide surface area for gas exchange

• only structures that contain alveoli can perform gas exchange; from respiratory bronchioles to alveoli

how does gas exchange work in alveoli?

During gas exchange, O2 diffuses through alveolar and capillary walls to enter the blood

• CO2 diffuses from the blood to alveoli

What are the properties of the lungs?

Soft, spongy, cone-shaped organs in the thoracic cavity separated by heart and mediastinum

• right lung as 3 lobes, left lung has 2 lobes

• Hilum

• pleura

• visceral pleura

• parietal pleura

• pleural cavity

What is the hilum?

region on medial surface of each lung through which bronchusi and large blood vessels enter

What is the pleura?

double-layered serous membrane surrounding lungs

What is visceral pleura?

inner layer of serous membrane; attached to surface of lung

What is parietal pleura?

outer layer of serous membrane; lines thoracic cavity

What is the pleural cavity?

potential space between visceral and parietal pleura

What are 4 examples of lung irritants?

1. asbestos

2. berylliosis

3. extrinsic allergic alveolitis

4. air pollution

What is asbestos?

A naturally occurring mineral, formerly used in buildings because it resists burning

• airborne fibers can lead to scarring of lungs, shortness of breath, lung cancer, mesothelioma

What is berylliosis?

beryllium is an element used in some industrial applications

• exposure to dust or vapor evokes immune response that scars lungs and impairs breathing

What is extrinsic allergic alveolitis?

Results from long-term exposure to dust of organic origin

• acute form causes fever and breathing impairment

• chronic form changes lungs over time

What is air pollution?

microfine airborne pollutants can pass through protective mechanisms and reach alveoli

• may worsen asthma, irritate eyes and lungs

• increases risk of heart disease and lung cancer

What is atmospheric pressure?

Force that moves air into lungs

• at seas level, equals 760mmHg

• when respiratory muscle are at rest, atmospheric pressure and alveolar pressure are equal

What is boyle’s law?

Pressure and volume of gases are inversely proportional

• if pressure inside the alveoli (intra-alveolar pressure) decreases, atmospheric pressure pushes air into airways

• this occurs during normal, resting inspiration, as phrenic nerves stimulate diaphragm to contract downward

• volume of thoracci cavity inc, which dec the presure from 760mmHg to 758mmHg

• in response to pressure difference, air rushes into thoracic cavity

What is the inspiration/expiration pathway of the lungs?

1. at rest, atmospheric and intrapulmonary pressures are equal→ isovolumic

2. in inspiration, the thoracic cavity expands laterally, vertically, and anteriorly

• intrapulmonary pressures drops below atmospheric pressure→ air flows into lungs

3. in expiration, the thoracic cavity contracts in all 3 directions

• intrapulmonary pressures drops rises above atmospheric pressure and air flows out of lungs

What is normal, resting inspiration?

Diaphragm and external intercostal muscles enlarge the size of the thoracic cavity

• lung expansion is aided by surface tension in the pleural cavity

• surfactant reduces surface tension in alveoli→ helps lung expansion

What is maximal inspiration?

Requires contraction of several other muscles to enlarge thoracic cavity even more

• pectoralis minors, SCMs, and scalenes are used

What are the major events of inspiration?

1. impulses are conducted on phrenic nerves to muscle fibers in diaphragm, contracting them

2. as dome-shaped diaphragm moves downward, thoracic cavity expands

3. at the same time, external intercostal muscles enlarge contract, raising the ribs and expanding the thoracic cavitty further

4. intra-alveolar pressure decreases

5. atmosphere pressure forces air into respiratory tract through air passages

6. lungs then fill w/ air

how do the muscles help w/ inspiration?

1. external intercostal muscles pull ribs up and out

2. diaphragm contracts

3. sternum moves up and out

4. SCM elevates sternum

5. scalenes elevate first 2 ribs

6. pectoralis minor elevates ribs

7. diaphragm contracts more

What are the properties of normal resting expiration?

1. elastic recoil of lung tissues and abdominal organs occur as tissues return to original shape at the end of inspiration

2. surface tension develops on moist surfacce of the alveolar linings→ shrinks alveoli

3. these factors inc intra-alveolar pressure about 1mmHg above atmospheric pressure, forcing air out of lungs

• a passive process that does not involve muscle contraction

What is maximal (forced, deep) expiration?

Due to contraction of internal intercostal and abdominal muscles

• inc abdominal pressure forces diaphragm into higher position→ pushes more air out of lungs

What are respiratory volumes?

Various volumes of air that can be moved into or out of lungs

• different degrees of effort in breathing move different volumes of air in and out of lungs

what is spirometry?

Measurement of these air volumes

What are the respiratory volumes that can be measured by spirometer?

1. tidal volume (TV)

2. inspiratory reserve volume (IRV)

3. expiratory reserve volume (ERV)

What is vital capacity (VC)?

The maximum volume of air that can be exhaled after taking the deepest breath possible

• Varies w/ age, gender, body size

• VC=TV+IRV+ERV

• 4600mL

What is tidal volume (TV)?

Volume of air moved in o out of lungs during respiratory cycle

• 500mL avg

What is inspiratory reserve volume (IRV)?

maximum volume of air that can be inhaled at the end of a resting inspiration

• 3000mL

What is expiratory reserve volume (ERV)?

maximum volume of air that can be exhaled at the end of a resting expiration

• 1100 mL

What is residual volume (RV)?

Volume of air that remains in thte lungs even after a maximal expiratory effort

• 1200 mL

What is inspiratory capacity (IC)?

Maximum volume of air that an be inhaled following exhalation of resting tidal volume

• IC=TV+IRV

• 3500mL

What is functional residual capacity (FRC)?

volume of air that remains in lungs following exhalation of resting tidal volume

• FRC=ERV+RV

• 2300mL

What is total lung capacity (TLC)?

total volume of air that the lungs can hold

• TLC=VC+RV

What are Dead Air Spaces?

Some air entering respiratory tract during breathing does not reach functional alveoli

What is an anatomical dead space?

Air in respiratory tract that remains in conduction structures

• does not reach alveoli

What is alveolar dead space?

Air in respiratory tract that reaches nonfunctional alveoli

• alveoli w/ poor blood fow

What is physiologic dead space?

Total of anatomical and alveolar dead space

• anatomic dead space=Physiological dead space (150mL/breath)

What are minute ventilations?

Volume of new atmospheric air moved into respiratory passages each minute

• MV= tidal volume (TV)xrespiratory rate (RR)

• since some new air in each breath remains in physiologic dead space, another figure can be calculated to represent actual amount of inhaled air that reaches alveoli each minute

What is the Alveolar Ventilation Rate (AVR)?

AVR= tidal volume (TV)-Physiological dead space (PDS), then multiplied by breathing ratet

• AVR=RR*(TV-PDS)

• this is the volume of air that reaches the alveoli each minute

• very important tbc it impacts the concentrations of O2 and CO2 in alveoli

What is coughing/

deep breath is taken, glottis is closed

• air is forced against closer and then glottis opens

• a blast of air passes upwards, clearing lower respiratory passages

What is sneezing/

Deep breath is taken, glottis is closed and air is forced against closure

• glottis opens and air passes upwards into nasal cavity

• uvula is depressed, and clears upper respiratory passages

What is laughing?

Deep breath is release in a series of short expirations

• expresses happiness

What is crying/

deep breath released in a series of short expirations

• expresses sadness

What is hiccuping?

diaphragm contracts spasmodically while glottis is closed

What is yawning?

Deep breath is taken

What is speech?

air is forced through the larynx, causing vocal cords to vibrate; actions of lips, tongue and soft palate form words

What is bronchial asthma?

allergic reaction to foreign antigens in airway

• in smaller airways, mucus and secretion from allergic response accumulates

• allergens and secretions irritate smooth muscle, leading to bronchoconstriction and wheezing

what is emphysema?

Progressive, degenerative disease in which alveolar walls are destroyed

• clusters of alveoli merge into larger ones, decreasing surface area for gas exchange

• alveolar walls lose elasticity and capillaries diminish

• requires a lot of muscular effort to breath

• a type of COPD along w/ chronic bronchitits

What is COPD?

chronic obstructive pulmonary disease

How is breathing controlled?

Normal breathing is a rhythmic, involuntary act that continues when a person is unconscious

• respiratory muscles can also be controlled voluntarily

What are respiratory areas?

groups of neruons in the brainstem that control breathing

• initiatte impulses that travel on cranial and spinal nerves, causing inspiration and expiration

• adjust rate and depth of breathing

What are the main respiratory areas?

1. medullary respiratory center

2. pontine respiratory groups

What is the medullary respiratory center?

2 groups of neurons

1. ventral respiratory group: sets basic rhythm of breathing

2. dorsal respiratory group: modifies activity of ventral group

What is the pontine respiratoy groups?

Help set rhythm of breatthing by limiting duratiton of each inspiration

What is the order respiratory areas?

1. ponttine respiratory group is located superior to pons

2. UMN descends and splits in medulla oblongata to ventral and dorsal respiratory groups (medullary respiratory center)

3. from respective ventral/dorsal groups, respiratory muscles are innervated via LMNs

What is the partial pressure of O2 in atmospheric air?

Air is 21% O2

• 0.21×760mmHg= 160mmHg= Partial pressure of O2

• PO2

What are the factors that affect breathing?

1. partial pressure of O2

2. partial pressure of CO2

3. H+ concentratiton in body fluids

4. degree of stretch of lung tissue

5. emotional state

6. level of physical activity

7. receptors (mechanoreceptors, central and peripheral chemoreceptors)

What is the control of ventrilation by chemoreceptors?

1. decreased ventrilation will be corrected by negative feedback→ increased ventilation

2. Increased arterial PCO2 will decrease blood pH and increase Plasma CO2

3. inc plasma CO2 will diffuse through blood CSF

4. CO2 is sensed by chemoreceptors in medulla oblongata→ sends signal to respiratory center in medulla oblongata

5. Decrease in blood pH is also sensed by chemoreceptors in aortic and carotid bodies→ signal sent to respiratory center

6. Signal descends to spinal cord motor neurons, to respiratory muscles

7. Muscles will increase ventilation