anatomy 2 lecture 2

Anatomy of respiratory system

organs of this system are found ion the head, neck, thoracic cavity

Anatomy of respiratory system consist of…

hollow passages that collectively exchange gases

what do the hollow passages of respiratory system consist of?

* nose and nasal cavity
* pharynx (throat)
* larynx (voice box)
* trachea (windpipe)
* bronchial tree (in the lungs)

Lungs

* pair of spongy organs in thoracic cavity that are enclosed within the boundaries of the rib cage and diaphragm
* each contains the bronchial tree which ends in millions alveoli and their blood vessels are embedded in elastic connective tissue

alveoli

tiny air sacs, arranged in grape like clusters, where gases are exchanged

Functions of the respiratory system

* classified functionally into conducting and respiratory cells
* respiration
* regulation of blood pH
* voice production
* olfaction
* protection

conducing zone

includes tubes through which air travels on its way into (inspired or inhaled) and out (expired or exhaled) of the body

what happens in conducting zone?

* air is filtered, warmed, and moistened as it travels through conducting zone
* includes structures from nose and nasal cavity to bronchioles

respiratory zone

Site of gas exchange (alveoli)

Respiration

Process that provides body cells with oxygen and removes carbon dioxide

regulation of Blood pH

can be altered by changing carbon dioxide levels in blood

Voice production

movement of air past the vocal folds make sound and speech

olfaction

smell occurs when airborne molecules are drawn into nasal cavity

protection

deters microbes by preventing entry and removing them from respiratory surfaces

Steps of respiration

* Pulmonary ventilation
* pulmonary gas exchange (external respiration)
* gas transport
* tissue gas exchange (internal respiration)
* cellular respiration

Pulmonary Ventilation

Movement of air in and our of lungs

Pulmonary gas exchange (external respiration)

Movement of gases between lungs and blood

Gas transport

movement of gases through blood

tissue gas exchange (internal respiration)

movement of gases between blood and tissues

cellular respiration

use of oxygen by the cells and production of carbon dioxide by the cell

nose and nasal cavity functions

* inhaled air is warmed and humidified
* debris is filtered from inhaled air and antibacterial substances are secreted
* olfactory receptors are housed
* enhances the resources of voice

paranasal sinuses

hollow cavities found within frontal, ethmoid, sphenoid, and maxillary bones

* war and humidify air, enhance voice resonance and reduce weight of skull

pharynx (throat)

dived into three divisions:

* nasopharynx
* oropharynx
* laryngopharynx

nasopharynx

lined with pseudostratified ciliated columnar epithelium for warming, humidifying, and filtering inspired air

oropharynx

lined with nonkeratinized stratified squamous epithelium for protection; passageway for both air and food

laryngopharynx

also lined with nonkeratinized stratified squamous epithelium and connects to larynx

larynx (voice box)

* maintains an open passageway for an air movement (multiple cartilages keep it open)
* epiglottis and vestibular folds prevent swallowed material from entering trachea
* vocal folds are the primary source of sound production
* pseuodostratified ciliated columnar epithelium traps debris, preventing their entry into the lower respiratory tract

trachea (windpipe)

hyaline cartilage rings cover anterior and lateral surfaces of trachea in a C shape, leaving posterior surface uncovered for swallowing

* mucosa of trachea is lined with pseudostratified ciliated squamous epithelium and goblet cells (produce mucus)

smokers cough

* deep, rattling cough of a smoker is linked directly to numerous adverse effects of smoke on the respiratory system
* chemicals in smoke
* as a result, more mucus is present, but cilia are less able to sweep it out of airways

chemicals in smoke

aact as errants, increasing mucua secretion

partially paralyze and eventually destroy cilia lining tract

Bronchial tree

Branches

* two primary bronchi
* five secondary bronchi
* approximately ten tertiary bronchi

Two primary bronchi

one to each lung

five secondary bronchi

two in the left lung and three in the right lung

Bronchioles bronchi into…

Terminal bronchioles and the respiratory bronchioles

What do the bronchioles tree have

small airways have smooth muscle but very few cilia and no cartilage

Respiratory zone begins with…

Respiratory bronchioloes with alveoli budding from walls

what do the respiratory bronchioles branch into

two or more alveolar ducts which end in alveolar sacs, where gas exchange occurs

Alveoli (alveolar sacs)

are the gas exchange sites of the respiratory system and their cell membranes are the “respiratory membrane”

Each alveolus has three cell types

type 1

type 2

alveolar macrophages

Type 1

alveolar cells are very thin squamous cells that allow rapid diffusion of gases

type 2

alveolar cells are cuboidal cells that produce surfactant (reduces surface tension)

alveolar macrophages

are phagocytes that clean up and digest debris

what is tuberculosis caused by

mycobacterium tuberculosis which spreads easily via air

* 90% of infections are latent (asymptomatic) and 10% are active (show symptoms)

Symptoms of tuberculosis

persistent cough with blood tinged sputum, fever, night sweats, weight loss

Alveolar infections triggers what?

inflammation and immune attempt to “wall off” infected area results in a granuloma

Pressure and volume:

Pulmonary ventilation (breathing) consists of two phases:

* inspiration or inhalation (brings air into lungs)
* expiration or exhaled (moves air out of lungs)

pressure volume relationship provides …

the driving force pulmonary ventilation

air is a mixture of what

higher pressure (outside air) to and area of lower pressure (alveoli)

Boyles law (pressure and volume)

states that constant temperature and number of gas molecules, the pressure and volume of a gas are inversely related

Pulmonary ventilation involves

volume changes in the thoracic cavity and lungs that lead to the creation of pressure gradient that moves air

expiration is a mostly passive process that occurs when

inspiratory muscles relax and recoil

forced inspiration and expiration involve…

additional muscles of the thorax and abdomen

non respiratory movements

include sighs, yawns, sneezes, and coughs

sigh

slow, deep inspiration followed by slow expiration that reopens collapsed alveoli

yawn

large sigh that takes lung volume to inspiratory capacity ( largest inspiration)

sneeze

forceful expiration through nose (up to 100 mph) that clears foreign or irritating substances

cough

can be almost 500 mph to clear larynx , trachea, or lower airways

what are the three physical factors of respiratory tract and lungs influence pulmonary ventilation

airway resistance

alveolar surface tension

pulmonary compliance

airway resistnece

* anything that impedes air flow through respiratory tract
* largely determined by diameter of bronchioles which is controlled by smooth muscle contraction
* \

alveolar surface tension

* alveoli are covered with a thin film composed mainly of water creating gas-water boundary
* occurs because of the partial charges from waters hydrogen bonds

pulmonary compliance

* refers to the ability of lungs and chest wall to stretch
* is determined by the ability of the elastic tissue of the lungs and the ability of the chest wall to move or stretch during inspiration

surfactant (produced by type 11 alveolar cells)

reduces surface tension and allows alveolus to remain partially open even during expiration

conditions that decrease compliance

pulmonary fibrosis

pulmonary edema

increased resistance to airflow because of the airway obstruction (asthma, bronchitis, lung cancer)