11.1 The Respiratory System Flashcards
What is the function of the respiratory system?
to allow oxygen from the air to enter the blood and carbon dioxide from the blood to exit into the air, restoring pH
What is the respiratory system?
a type of organ system consisting of the lungs and tubes that take air to and from the lungs
What is ventilation?
(another term for breathing) encompasses inspiration and exhalation
How do the respiratory and circulatory systems work together to maintain homeostasis?
- external respiration
- transport of gases to and from the lungs and the tissues
- internal respiration
What is external respiration?
the exchange of gases (oxygen and carbon dioxide) between air and the blood
What is internal respiration?
the exchange of gases (oxygen and carbon dioxide) between the blood and tissue fluid
What makes gas exchange with the environment necessary?
cellular respiration, which produces ATP, uses the oxygen and gives up carbon dioxide
What happens to air as it moves in along the airways?
filtered, warmed, and moistened
How is air filtered in the airways?
- by coarse hairs just inside the nostrils
- by cilia and mucus in the nasal cavities, and in the other airways of the respiratory tract
What are cilia’s job in the nose?
the hairs and cilia act as screening devices
What do cilia do in the trachea and other airways do?
the cilia beat upward, carrying mucus, dust, and occasional bits of food that “went down the wrong way” into the pharynx, where the accumulation can be swallowed or expelled
How is air warmed in the airways?
by heat given off by the blood vessels lying close to the surface of the lining of the airways
How is air moistened in the airways?
by the wet surface of these passages (heat given off by the blood vessels lie close to the surface of the lining of the airways)
What happens when air moves out during expiration?
it cools and lose moisture
What happens as air cools?
- it deposits more moisture on the lining of the trachea and the nose, and the nose may drip as a result of this condensation
- air still retains moisture, however, that upon expiration on a cold day, it condenses and can be seen as a small cloud
Name the parts of the upper respiratory tract. (4)
nose
nasal cavities
pharynx
larynx
Where does air enter through the nose?
through external openings called nostrils
How many nasal cavities does the nose contain?
2
What are nasal cavities?
narrow canals separated from one another by a septum composed of bone and cartilage
What lines nasal cavities?
mucous membranes
What are bony ridges?
they project laterally into the nasal cavity
What do bony ridges do?
increase SA for moistening and warming air during inhalation and for trapping water droplets during exhalation
Where are chemoreceptors located?
on the endings of ciliated cells located high in the recesses of the nasal cavities
Why does crying often produce a runny nose?
the tear (lacrimal) glands drain into the nasal cavities vy way of tear ducts
What are sinuses?
air-filled spaces that reduce the weight of the skull and act as resonating chambers for the voice
What are nasal cavities separated from the mouth by?
a partition called the palate
What are the 2 portions of the palate?
hard palate: (anteriorly) is supported by bone
soft palate: (posteriorly) is made of muscle tissue surrounded by a mucous membrane
What is the pharynx (throat)?
a funnel-shaped passageway that connects the nasal and oral cavities to the larynx
What are the 3 parts of the pharynx?
nasopharynx: where nasal cavities open posterior to the soft palate
oropharynx: where the mouth opens
laryngopharynx: opens the larynx
What is the soft extension of the soft palate?
the uvula, which projects into the oropharynx that you can see by looking into your throat using a mirror
What are tonsils?
lymphatic tissue containing lymphocytes that protect against invasion by inhaled bacteria and viruses
What do tonsils do?
form a protective ring at the junction of the mouth and the pharynx
Where does air and foo both pass in?
the pharynx
Where is the larynx located?
above and in front of the esophagus, and leads to the trachea
Why are the layrnx and the trachea usually open?
allows air to pass
Why is the esophagus normally closed?
opens only when a person swallowa
Where does gas exchange occur between?
air in the alveoli and blood within a capillary network that surrounds the alveoli
Describe gas exchange of the respiratory system.
- pulmonary arteriole carries oxygen-poor blood away from the heart to the alveoli
- carbon dioxide leaves the blood, oxygen enters the blood
- pulmonary venule carries oxygen-rich blood from the alveoli toward the heart
What is the larynx?
a cartilaginous structure that serves as a passageway for air between the pharynx and the trachea
What can the larynx be pictured as?
a triangular box whose apex, the Adam’s apple, is at the front of the neck
Why is the larynx also called and why?
called the voice box because it houses the vocal cords
What are vocal cords?
mucosal folds supported by elastic ligaments
What is the glottis?
the slit between the vocal cords
How do vocal cords produce sounds?
when air is expelled past the vocal cords through the glottis, the vocal cords vibrate, producing sound
What is the difference between male and female in the growth of the larynx and vocal cords during puberty?
the growth of the larynx and vocal cords is much more rapid and accentuated in males than females, causing males to develop a more prominent Adam’s apple and a deeper voice
Why do the voice “break” in young males?
due to the inability to control the vocal cords
How is the high or low pitch of the voice regulated when speaking and singing?
by changing the tension on the vocal cords
What happens when there is a greater tension on the vocal cords?
- the glottis becomes more narrow
- the greater the tension, the higher the pitch
What does the loudness/intensity of the voice depend upon?
the amplitude of the vibrations (the degree to which the vocal cords vibrate)
What is the epiglottis?
a flap of tissue that prevents food from passing into the larynx
What happens when food is swallowed?
the larynx moves upward against the epiglottis
What is the trachea (windpipe)?
a tube connecting the larynx to the primary bronchi
Where is the trachea located?
lies in front of the esophagus and is held open by C-shaped cartilaginous rings
Where does the open part of the C-shaped rings face and why?
faces the esophagus, which allows the esophagus to expand when swallowing
What lines the trachea?
mucosa
What does mucosa have?
a layer of pseudostratified ciliated columnar epithelium
What do cilia that project from the epithelium do?
keep the lungs clean by sweeping mucus (produced by goblet cells) and debris toward the pharynx
*smoking is known to destroy these cilia
What collects in the lungs from smoking?
toxins in cigarette smoke
What are the bronchi?
the trachea divides into right and left primary bronchi which lead into the right and left lungs
What are bronchioles?
small tubes that conduct air from the bronchi to the alveoli
What do bronchi branch into?
a great number of secondary bronchi that eventually lead to bronchioles
Describe the structure of bronchi.
resemble the trachea in structure, but as the bronchial tubes divide and subdivide, their walls become thinner and the small rings of cartilage are no longer present
What does each bronchiole lead to?
an elongated space enclosed by millions of thin-walled sacs called alveoli
What composes the lungs?
the components of the bronchial tree beyond the primary bronchi
What are alveoli?
air sacs or air pockets in the lungs
What are lungs?
paired, cone-shaped organs that occupy the thoracic cavity except for a central area that contains the trachea, thymus, heart, and esophagus
How many lobes do the right and left lungs have?
right: 3
left: 2
Why does the left lung only have 2 lobes?
allows room for the heart, whose apex points left
What are lobes further divided into?
lobules, and each lobule has a bronchiole serving many alveoli
What is the diaphragm?
the muscle that separates the thoracic cavity from the abdominal cavity
Describe the structure of the lungs.
- apex is narrow
- base is broad and curves to fit the dome-shaped diaphragm
What is the pleura?
- a very thin serous membrane that covers each lung
- another pleura covers the internal chest wall and diaphragm
What do pleura membranes produce?
a lubricating serous fluid that helps the pleurae slide freely against each other during inspiration and expiration
What is surface tension?
the tendency for water molecules to cling to each other due to hydrogen bonding between the molecules
What does surface tension do for pleurae?
it holds the 2 pleurae layers together when the lungs recoil during expiration
What happens to air with each inhalation?
air passes by way of the respiratory passageways to the alveoli
What is each alveolus made up of?
simple squamous epithelium surrounded by blood capillaries
Where does gas exchange occur?
between the air in an alveolus and the blood in the capillaries
How does gas exchange occur?
- oxygen diffuses across the alveolar and capillary walls to enter the bloodstream
- carbon dioxide diffuses from the blood across these walls to enter the alveoli
What must alveoli do during gas exchange?
stay open to receive the inhaled air
What is capable of causing alveoli to close up?
the surface tension of fluid coating the alveoli
What prevents the alveoli from closing?
they are coated with PULMONARY SURFACTANT
What is pulmonary surfactant?
a lipoprotein that lowers the surface tension and prevents alveoli from closing
What is infant respiratory distress syndrome?
- the lungs collapse in newborns who lack pulmonary surfactant
- leading cause of death of babies born prematurely
How is infant respiratory distress syndrome treated?
by inserting a plastic tube into the trachea and administering oxygen as well as surfactant that is either synthetic or extracted form cows’ lungs
What is extra-corporeal membrane oxygenation?
severely ill patients of infant respiratory distress syndrome can receive this treatment in which a cannula is installed in a large blood vessel, through which blood flows into a machine that adds oxygen and removes carbon dioxide before being returned to the patient
