Respiratory system - Lecture Notes - TIU - Lecture Notes

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Respiratory system

Transcript of Respiratory system - Lecture Notes - TIU - Lecture Notes

Page 1: Respiratory system - Lecture Notes - TIU - Lecture Notes

Respiratory system

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Respiratory System

Functionally

Consists of the respiratory and conducting zones

Respiratory zone

Site of gas exchange

Consists of bronchioles, alveolar ducts, and alveoli

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Respiratory System

Functionally

Consists of the respiratory and conducting zones

Respiratory zone

Site of gas exchange

Consists of bronchioles, alveolar ducts, and alveoli

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Respiratory System

Conducting zone

Provides rigid structures for air to reach the sites of gas exchange

Includes all other respiratory structures (e.g., nose, nasal cavity, pharynx, trachea)

Respiratory muscles – diaphragm and other muscles

that promote ventilation

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Respiratory System● Consists of upper and lower

parts

● The upper respiratory

include nose, nasal cavity,

laryngopharynx and larynx

●The lower respiratory

include,the trachea, bronchi,

bronchial tree, and the lungs

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The Nose• The nose consists of the external nose and the nasal

cavity, both of which are divided by a septum into right and left halves.

• External NoseThe external nose has two elliptical orifices called the

nostrils, The lateral margin, the ala nasi, is rounded and mobile.

• Nasal Cavity The nasal cavity extends from the

nostrils in front, to the posterior nasal apertures or choanae behind, where the nose opens into the nasopharynx.

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Structure of the Nose

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Structure of the Nose

• The nose is divided into two regions:

The external nose

The internal nasal cavity

The external nose, including the root, bridge, dorsum nasi, and apex

Philtrum – a shallow vertical groove inferior to the apex

The external nares (nostrils) are bounded laterally by the alae

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Nasal Cavity

• Lies in and posterior to the external nose

• Is divided by a midline nasal septum

• Opens posteriorly into the nasal pharynx via internal nares

• The ethmoid and sphenoid bones form the roof

• The floor is formed by the hard and soft palates

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Nose

External nasal openings

(nostrils or nares)

Internal nasal

(choanae).

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Vestibule – nasal cavity superior to the nares

Vibrissae – hairs that filter coarse particles from

inspired air

Olfactory mucosa

Lines the superior nasal cavity

Contains smell receptors

Nasal Cavity

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Nasal Cavity

Respiratory mucosa

Lines the balance of the nasal cavity

Glands secrete mucus containing lysozyme and

defensins to help destroy bacteria

Inspired air is:

Humidified by the high water content in the nasal cavity

Warmed by rich plexuses of capillaries

Ciliated mucosal cells remove contaminated mucus

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Nasal Cavity

Superior, medial, and inferior conchae:

Protrude medially from the lateral walls

Increase mucosal area

Enhance air turbulence and help filter air

Sensitive mucosa triggers sneezing when stimulated by

irritating particles

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Function of the NoseThe only externally visible part of the respiratory system

that functions by Providing an:

airway for respiration

Moistening (humidifying) and warming the entering air

Filtering inspired air and cleaning it of foreign matter

Serving as a resonating chamber for speech

Housing the olfactory receptors

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Regions of the nasal cavity

Nasal vestibule

Olfactory area

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Kiesselbach’s plexus or Little's area

• Kiesselbach’s plexus is an integral anastomosis of five branches converging in the anterior inferior quadrant of the nasal septum (over the septal cartilage). The area has been referred to as Little’s Area, Kiesselbach’s Triangle or Kiesselbach’s Area. Little’s area is a common site of epistaxis (nose bleeds) in both paediatric and adult cases.

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Little's area

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-Epistaxis

-Rhinorrhea

-Rhinitis

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• Sinuses in bones that surround the nasal cavity

• Sinuses lighten the skull and help to warm and moisten the air

Paranasal Sinuses

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Paranasal sinuses● Air cavities located in the bones of skull around the nose

and open in the lateral wall of the nasal cavity.

● They include frontal, ethmoidal, sphenoidal and maxillary air

sinuses.

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Pharynx

It is divided into three regions

Nasopharynx

Oropharynx

Laryngopharynx

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The Pharynx● 12-13 cm long muscular tube lies behind the oral, nasal

and laryngeal cavities.

● Extends from the base of skull to the lower border of

cricoids cartilage at the level of lower border of 6th cervical

vertebra where it continues with esophagus.

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NasopharynxLies posterior to the nasal cavity, inferior to the

sphenoid, and superior to the level of the soft palate

Strictly an air passageway

Lined with pseudostratified columnar epithelium

Closes during swallowing to prevent food from

entering the nasal cavity

The pharyngeal tonsil lies high on the posterior wall

Pharyngotympanic (auditory) tubes open into the

lateral walls

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Oropharynx

Extends inferiorly from the level of the soft palate to the epiglottis

Serves as a common passageway for food and air

The epithelial lining is protective stratified squamous epithelium

Palatine tonsils lie in the lateral walls

Lingual tonsil covers the base of the tongue

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Oro-pharynx ● Lies behind the oral cavity

● Its junction with nasopharynx at the isthmus or called

oropharyngeal orifice

● It contains the palatine tonsils in its lateral walls

Laryngo-pharynx:● Lies behind the larynx and continupus anteriorly with the

inlet of larynx.

● On each side of inlet of larynx, the laryngopharynx has a

dead space called piriform recess which is the site for

stagnation of food stuff and foreign bodies.

● Inferiorly, it is continuous with the esophagus

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The Pharynx● long muscular tube

lies behind the oral, nasal

Parts of Pharynx

1. Naso-pharynx

2. Oro-pharynx

3. Laryngo-pharynx

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Laryngopharynx

Lies posterior to the upright epiglottis

Extends to the larynx, where the respiratory and

digestive pathways diverge

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Larynx● A phonation box and air passage, located in the middle

anterior part of the neck.

● It is made of a number of cartilages connected together by

membranes, ligaments, muscles

.

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Larynx

Short passageway connecting laryngopharynx with trachea

Composed of 9 pieces of cartilage

Thyroid cartilage or Adam’s apple

Cricoid cartilage hallmark for tracheotomy

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Cavity of Larynx● Extends from inlet of larynx to the beginning of trachea

● In the central, middle part of laryngeal cavity, it contains

two pairs of vocal folds or cords

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Epiglottis closes off glottis during swallowing

elastic cartilage that covers the laryngeal inlet

during swallowing

Glottis – pair of folds of mucous membranes, vocal folds (true vocal cords, and rima glottidis (space)

Cilia in upper respiratory tract move mucous and trapped particles down toward pharynx

Cilia in lower respiratory tract move them up toward pharynx

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Larynx (Voice Box)

Attaches to the hyoid bone and opens into the

laryngopharynx superiorly

Continuous with the trachea posteriorly

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Framework of the Larynx

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Attaches to the hyoid bone and opens into the

laryngopharynx superiorly

Continuous with the trachea posteriorly

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Structures of Voice Production

Mucous membrane of larynx forms

Ventricular folds (false vocal cords) – superior pair

Function in holding breath against pressure in

thoracic cavity

Mucosal folds superior to the true vocal cords

Have no part in sound production

Vocal folds (true vocal cords) – inferior pair

Vibrate and produce sound with air

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Sphincter Functions of the Larynx

The larynx is closed during coughing, sneezing, and Valsalva’s maneuver

Valsalva’s maneuver

Air is temporarily held in the lower respiratory tract by closing the glottis

Causes intra-abdominal pressure to rise when abdominal muscles contract

Helps to empty the rectum

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Functions of larynx

The three functions of the larynx are:

To provide a patent airway

To act as a switching mechanism to route air and

food into the proper channels

To function in voice production

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Trachea● Extends from larynx to

superior border of T5

Divides into right and left

primary bronchi

The trachea begins at the

laryngeal outlet

and terminates at the level of

the sternal angle, by dividing

into the right and left bronchi

(carina = bifurcation of

trachea)

● It is 10 cm long having a

fibromuscular wall supported by

a number of C-shaped hyaline

cartilages.

Trachialis

C-shaped hyaline cartilages

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Bronchi and

Bronchial Tree● The right and left

principle bronchi begins

at the level of sternal

angle

● The right principle

•The left principle

bronchus

Tertiary bronchus

(Bronchopulmonary Segment)

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BronchiRight and left primary bronchus goes to right and left lungs

Carina – internal ridge

Most sensitive area for triggering cough reflex

Divide to form bronchial tree

Secondary lobar bronchi (one for each lobe), tertiary (segmental) bronchi, bronchioles, terminal bronchioles

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• upper lobe

• middle lobe

• lower lobe

•transverse

fissures.

•Oblique

fissures.

• upper lobe

• lower lobe

•Oblique

fissure.

• pleural sac

Lungs

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Gross Anatomy of the LungsLungs occupy all of the thoracic cavity except the

mediastinum

Root – site of vascular and bronchial attachments

Costal surface – anterior, lateral, and posterior

surfaces in contact with the ribs

Apex – narrow superior tip

Base – inferior surface that rests on the diaphragm

Hilus – indentation that contains pulmonary and

systemic blood vessels

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❖The costal surface of the lung is large,

smooth, and convex. It is related to the costal pleura,

which separates it from the ribs, costal cartilages,

and innermost intercostal muscles.

❖The mediastinal surface of the lung is

concave because it is related to the middle

mediastinum, which contains the pericardium and

heart. The mediastinal surface includes the hilum,

which receives the root of the lung.

❖ The diaphragmatic surface of the lung, which is

also concave, forms the base of the lung, which rests

on the dome of the diaphragm

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The hilum of the lung

is a wedge-shaped area on

the mediastinal surface of

each lung through which the

structures forming the root of

the lung pass to enter or exit

the lung.

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Pleura● Serous sac investing the lungs.

● Consists of outer parietal and inner visceral layers

separated by a small space called pleural cavity.

-Pleuritis

-Pneumothorax

-Haemothorax

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Each lung enclosed by double-layered pleural membrane

Parietal pleura – lines wall of thoracic cavity

Visceral pleura – covers lungs themselves

Pleural cavity is space between layers

Pleural fluid reduces friction, produces surface tension (stick together)

Pleura

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Diaphragm

❖ Is the musculotendenous it has two parts

• Muscular part fixed

• Central part movable• The fibers of the

muscular part radiated in the center forming central tendon and it has no bony attachments

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Opening of the diaphragm

• Aortic hiatus at the level

of T12 for aorta

• Esophagus hiatus at the

level of T10 for esophagus

• Caval opening for IVC at

the level of T8

Caval opening

Aortic hiatus

Esophageal

opening

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Intercostal muscles

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