APHY164 LO5

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upper respiratory tract function

warming and humidifying inspired air

responsible for the senses of smell and taste, swallowing

upper respiratory tract structures

nose, nasopharynx, oropharynx, larynopharynx, and larynx

nose and nasal cavities structure and function

cilia are small hairs that filter out dust and large foreign particles

the palate is a bony structure that separates the nasal cavity and the mouth

the septum is a vertical plate of bone and cartilage that separated nasal cavity into 2 halves

nasal cavity is lined with goblet cell rich epithelium

conchae/turbinates

3 bones in the nasal cavity that create narrow passageways that ensure that most air contacts the mucous membrane on the way through allowing the air to pick up moisture and heat from the mucosa and the dust from the air sticks the mucosa

sphenoid sinus

hollow cavity in the nasal cavity that drains mucus into the nasal cavity

pharynx

commonly called the throat, muscular tube located behind the nasal and oral cavities

divided into nasopharynx, oropharynx, and laryngophraynx

nasopharynx

lined with pseudostratified ciliated columnar cells which move mucus down to oropharynx

is a passageway for air

located posterior to the nasal cavity and extends down to level of soft palate

four openings in the wall: two internal nares and two openings to the Eustachian tubes from the ears

exchanges small amounts of air with auditory tubes so air pressure of middle ear = pressure of nares and pharynx

oropharynx

lined with conciliated cells

is a passage for air and food

located posterior to the oral cavity and extends from the soft palate to the hyoid bone

contains the palatine and lingual tonsils

laryngopharynx

lined with conciliated cells

passageway for air and food

extends downward from thyroid bone to join with the larynx and esophagus

larynx

connects the pharynx and trachea

wall is composed of cartilage

contains the vocal cords

prevents food and liquids from entering the trachea and produces sound

lined by nonkeratinized squamous epithelium above vocal cords and pseudostratified dilated columnar epithelium below the vocal cords

epiglottis

stem is attached to the thyroid cartilage and the leaf part opens or closes the opening to the glottis (open space between vocal cords and larynx)

closes the larynx while swallowing to keep food out of the lungs

thyroid cartilage

Adams apple

cricoid cartilage

ring like cartilage that links the larynx to the trachea

vestibular folds of the membrane of the larynx

play no role in speech

close the glottis during swallowing to keep food and liquids out of the airway

vocal cords

produce sound when air passes over them during exhalation

glottis

opening between the vocal cords

conduction zone

nose, pharynx, larynx, trachea, bronchi, terminal bronchioles

respiratory zone

respiratory bronchioles, alveolar ducts, alveolar sacs

conduction system

series of large pipes that carry air to the alveoli where gas exchange takes place

functions of the nose

1. airway for respiration, provides opening for air to enter

2. moistens and warms air, capillaries carry warm blood in mucous membranes and and moisture in mucus moistens

3. filters and cleans air, particles greater than 5um are trapped in mucus, cilia cause mucus to be carried into pharynx

4. smell, olfactory cells located in the upper part of the nasal chamber detect odours and transmit them to the brain

5. speech, resonating chamber for speech

paranasal sinuses

air filled cavities that connect the the nasal cavity

lined with ciliated epithelial cells and mucus producing goblet cells

lighten the skull, resonance chambers, warm and moisten air

four sinuses

frontal, above eyebrows

ethmoidal, far back

sphenoidal

maxillary, on either side of nose

lining of respiratory region is

pseudostratified ciliated columnar epithelial cells except in the vestibular region

they produce mucus and the cilia move mucus towards the pharynx for clearance

palatine tonsil

located at the back top of mouth right before larynx and consists of lymphoid tissue that helps protect against pathogens

lingual tonsil

located at the base of the tongue, consists of lymphoid tissue that aids in immune function and helps protect against pathogens

pharyngeal tonsil

located at the back of the nasal cavity, consists of lymphoid tissue that helps protect against pathogens and plays a role in the immune response

lower respiratory tract parts

trachea, bronchi, lungs

trachea

airway from larynx to lungs

extends from the larynx down to where it divides into the right and left bronchi ]

c shaped rings of cartilage prevent collapsing

lined with ciliated pseudostratified columnar epithelial cells and goblet cells

carina

cartilaginous ridge where the trachea branches into two primary bronchi

bronchial tree

all divisions of bronchial tree consist of elastic connective tissue

contains the primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, and alveolar ducts

primary bronchi

supported by c shaped rings of cartilage and lined by pseudostratified ciliated columnar epithelium

right bronchus is wider and more vertical than left which increases chances of obstruction

branch into secondary bronchi

secondary bronchi

one for each of lungs lobes (left has 2, right has 3)

branch off the primary bronchi and then into smaller tertiary bronchi

lined by pseudostratfied dilated columnar epithelium

tertiary bronchi

have irregular or no cartilage rings

18 small branches off the bronchi leading to 18 segments of the lung

branch into very small airways (bronchioles)

lined by pseudostratified ciliated columnar epithelium

bronchioles

less than 1mm wide and lack any supportive cartilage

divide into thin walled passages called alveolar ducts

alveolar ducts

branch from the respiratory bronchioles and then lead into alveolar sacs and finally alveoli

single layer of simple squamous epithelium

site of gas exchange

alveolar sacs

two or more alveoli that share a common opening

_______ blood flows into alveoli through _________ and ________ blood leaves alveoli via ____________

deoxygenated, pulmonary arterioles, oxygenated, pulmonary venules

what does the ability of alveoli to expand and recoil rely on

their elasticity and the compliance of surrounding lung tissue

lungs

fill the pleural cavity and extend from just above the clavicles to the diaphragm and lie against the anterior and posterior ribs

hilum

opening in the lungs medial surface that the primary bronchi and pulmonary blood vessels enter through also nerves and lymphatic vessels

apex of the lung

the top

right lung lobes and fissures

superior (top), middle, and the inferior

horizontal and oblique fissures

the base of each lung rests on the _________

diaphragm

why does the left lung only have two lobes?

because the heat extends toward the left

left lung lobes and fissures

superior and inferior lobes

oblique fissure separates them

left and right lung gas exchange contribution

right 55%

left 45%

visceral pleura

membrane that covers the surface of the lungs and extends into the fissures

parietal pleura

lines the entire thoracic cavity and covers the domes of the diaphragm

very fine serous membrane

firmly attached to the ribs

pleural cavity

the space between the visceral and parietal pleurae

contains pleural fluid that lubricates and creates a pressure gradient to assist with lung inflation

pneumothorax

when the thoracic wall is punctured and air rushed into the pleural cavity which causes the negative pressure to be lost and the lungs collapse

terminal bronchioles

no cartilage and lined by nonciliated simple columnar epithelium

smallest bronchioles have an average diameter of 0.5 mm

end of the bronchial tree and branch into respiratory bronchioles

respiratory bronchioles

gas exchange can occur here

lined by simple squamous epithelium

alveolus

cup shaped outpouching - epithelial lining and elastic membrane

site of gas exchange

single layer of simple squamous epithelium(type I and II) and elastic tissue

types of alveolar cells

type I: simple squamous good for diffusion of gases

type II: septal cells produce a mixture of phospholipids and lipoproteins called surfactant which reduces surface tension of fluid on the alveoli preventing collapse

macrophage: dust cell that wanders around and ingests foreign material

cardiac notch

the concave impression in the medial aspect of the left lung that accommodates for the heart

bronchopulmonary segments

lobes of lungs are further separated into segments which contain one tertiary bronchus

lobules

bronchopulmonary segments are broken into small compartments called lobules

each is wrapped in elastic connective tissue and contain arteriole, venule, lymphatic vessels, and a branch from a terminal bronchiole

mediastinum

structure containing the heart, great vessels, esophagus, and trachea

separates the lungs

pulmonary ventilation

breathing

respiratory cycle

one inspiration and one expiration

main muscle responsible for pulmonary ventilation

diaphragm

inspiration process

1. external intercostal muscles pull ribs upward and outward which widens the thoracic cavity (lungs expand with chest because of 2 layers of pleurae)

2. internal intercostals help elevate the ribs

3. the diaphragm contracts, flattens, and drops, which presses the abdominal organs downward and enlarges the thoracic cavity

4. the negative pressure between the visceral and parietal pleurae (inter pleural pressure) causes them to suction together and pull the lungs toward the parietal pleurae

5. when intrapleural pressure drops less than atmospheric pressure, air flows down the pressure gradient into the lungs

expiration process

1. external intercostal muscles relax which pulls the ribs downward

2. the diaphragm relaxes and bulges upward which presses against the base of the lungs reducing the size of the thoracic cavity

3. internal intercostals contract

4. air is pushed out of the lungs

accessory muscles in deep inspiration

muscles of the neck and chest contract to help elevate the chest

accessory muscles in forced respiration

rectus abdominus and external abdominal obliques contract to pull the lower ribs and sternum as the internal intercostals pull the other ribs downward

this allows more rapid exhalation

inspiratory centre

primary respiratory centre found in the medulla (brain stem)

controls inspiration and expiration (indirectly)

1. inspiratory center sends impulses to the intercostal muscles (intercostal nerves) and to the diaphragm (phrenic nerves)

2. inspiratory muscles contract causing inhalation

3. nerve output stops which makes the inspiratory muscles relax and the thoracic cage produces exhalation because of its elasticity (Boyles law)

the muscle used for breathing are _________ which means ___________

skeletal, they require nervous stimulation to contract

apneusitic center

found in the pons and stimulates the inspiratory centre to increase the depth and length of each inspiration

pneumotaxic centre

found in the pons and inhibits the apneustic and inspiratory centre to ensure a normal breathing rhythm and prevents overinflation

expiratory centre

found in the medulla sends pulses to the adominal and other accessory muscles when forceful exhalation is needed

due to the location of the phrenic nerve __________ injuries can make it impossible to breathe

spinal cord injury near the third cervical vertebrae

what allows you to voluntarily change breathing

cerebral cortex, however once the CO2 levels in the blood reach a certain level the respiratory enters override it

why is the pressure that drives respiration

the difference between atmospheric pressure and intrapulmonary pressure

inspiration occurs when

pressure within the lungs drops lower than the atmospheric pressure

expiration occurs when

atmospheric pressure is lower than the pressure in the lungs

passive process caused by the elasticity of the lung tissue

Boyles law

a given volume of gas will exert more pressure in a smaller space than a larger space

factors that affect airflow

diameter of bronchioles: bronchodilation increases airflow (epinephrine and sympathetic nerves) while bronchoconstriction decreases airflow (cold air, chemical irritants, histamine, parasympathetic nerves)

pulmonary compliance: elasticity of lung tissue

alveolar surface tension: in order for gas to enter or leave a cell it must be dissolved in a liquid which means each alveoli has a thin layer of water on its inner surface. the water molecules attract each other which can collapse the alveoli. surfactant is a lipoprotein that disrupts the electrical attraction between water molecules which lowers surface tension and prevents collapse

tidal volume

the amount of air inhaled and exhaled during quiet breathing

inspiratory reserve volume

the amount of air inhaled using maximum effort after a normal inspiration

expiratory reserve volume

the amount of air that can be exhaled after a normal expiration by using maximum effort

residual volume

even after forced expiration 1300ml of air remains in the lungs which ensures gas exchange continues between breaths

total lung capacity

maximum amount of air the lungs can contain

vital capacity plus the residual volume

vital capacity

the amount of air that can be inhaled and exhaled with the deepest possible breath

tidal volume combined with inspiratory and expiratory reserve volumes

anatomical dead space

the air that remains in conducting airways and doesn’t reach the alveoli so it can’t participate in gas exchange

physiological dead space

the air in the anatomical dead space and also the air in any alveoli that are ventilated but not perfused

how does oxygen cause variation in breathing

oxygen levels are sensed by peripheral chemoreceptors in the carotid and aortic bodies

low levels cause peripheral chemoreceptors to send impulses to the medulla to increase rate and depth of respirations

how does hydrogen ions (pH) cause variation in breathing

central chemoreceptors in the brainstem monitor pH of CSF which mirrors level of CO2 in the blood

falling pH levels indicate an excess of CO2 and central chemoreceptorssignal respiratory centres to increase rate and depth of breathing which helps get rid of extra CO2 raising pH level

hering-breuer reflex

receptors in the lungs and chest wall detect the stretching of the lungs and signal the respiratory centres to exhale and inhibit inspiration

this prevents overinflation

how can pain and emotion cause variation in breathing

the hypothalamus and limbic system send signals that affect breathing in response to pain and emotions

how can irritants cause variation in breathing

nerve cels in the airway respond to irritants by signalling the respiratory muscles to contract which results in a cough or sneeze

what is the primary regulator of respiration

carbon dioxide because it easily passes the blood brain barrier

rising CO2 levels stimulates an increase in rate and depth of respirations

in COPD lack of O2 causes the same stimulation

apnea

temporary cessation of breathing

biots respirations

abrupt, irregular breathing pattern where periods of apnea alternate with periods of breathing consistent in rate and depth

often a result of increased inter cranial pressure

bradypnea

abnormally slow breathing

cheyne-strokes respirations

cyclical breathing that begins with an increase in rate and depth of respirations followed by a gradual decrease in rate and depth of respirations, eliminating in a short period of apnea before repeating

usually in terminally ill or brain damaged

dyspnea

laboured or trouble breathing

eupnea

relaxed quiet breathing

hyperpnea

increased rate of breathing

hyperventilation

increased rate of respirations resulting in lowered blood levels of CO2