6 the Respiratory System

8/2/2019 6 the Respiratory System

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Anatomy of the Larynx

Thyrohyoidmembrane


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Cartilages of the Larynx

Hyaline cartilage:

1 thyroid cartilage 1cricoid cartilage

2 arytenoid cartilage

Fibroelastic cartilage:- the epiglottis

Thyrohyoidmembrane


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The Thyroid Cartilage

Laminae are separated, v-shape notch known as thyroidnotch

Upper part lined with

stratified squamous epithelium,

lower part with

ciliated columnar epitheliumThyrohyoidmembrane


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The Cricoid Cartilage

This lies below thyroid cartilage

Shaped like ring, circling the larynx with a narrow partanteriorly, broad part posteriorly

Broad part articulates with

arytenoid cartilages,

inferior cornu of

thyroid cartilage

lined with ciliatedcolumnar epithelium

Thyrohyoidmembrane


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The arytenoid cartilages:

Two roughly pyramid shaped

situated on top of broad part of cricoid cartilage

give attachment to vocal cords & muscles

lined with ciliated columnar epithelium


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The Epiglottis

Leaf shaped fibroelastic cartilage

Attached to the inner surface of the anterior wall of

thyroid cartilage, below thyroid notch

Covered with stratified squamos epithelium

Larynx is likened to a box and

epiglottis as a lid

So it closes of larynx during

swallowing & protect the lungs


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Interior of the larynx:

Vocal cords are two pale folds of mucousmembrane from the inner side of thyroid cartilage

anteriorly to the arytenoid cartilages posteriorly.

Muscles controlling the vocal cords are

Relaxed Contracted

Vocal cords open

(Abducted)

Vocal cords stretched out

(Adducted)

Pitch of the sound is low Pitch of the sound is high


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The Glottis

Vocal cord

abducted

Vocal cord

adducted


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Functions:

Production of sound:

1. Voice depends upon the length and tightness of vocal cord

2. Volume of the voice depends upon the force with which cords

vibrate

greater the force of expired air

more cords vibrate and the louder sound emitted3. Tone is depending upon the shape of the mouth, position

of tongue, lips, facial muscles and air in Para nasal sinuses


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Speech: This occurs during expiration when the sounds

produced by the vocal cords are manipulated by the

tongue, cheeks and lips

Protection of the lower respiratory tract: During

swallowing, larynx moves upwards, and epiglottis closes

over the larynx.

Passageway of air: between pharynx and trachea

Humidifying, filtering and warming


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What is the structure ofairways outside the lungs?


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Gross Anatomy of the Lungs


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The Lungs Two lungs, cone shaped having an

apex, base, costal surface & medialsurface

The Apex : rounded, rises into the rootof the neck, about 25 mm (1 inch)above the clavicle

structures associated: first rib, blood

vessels & nerves in root of the neck

The Base: concave in shape.

closely associated with the thoracic

(superior) surface of the diaphragm

Position and associated structures:


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The Costal surface: Surface is convex.

closely associated with cartilages, the ribs and

the intercostals muscles

The Medial surface: Surface is concave & has

roughly triangular shaped area called hilum atthe level of 5th, 6th & 7th thoracic vertebrae

Structures which form root of the lung enter &

leave at the hilum, include

primary bronchus,

-pulmonary artery supplying

the lung & two pulmonary veins draining it,

- bronchial artery & veins, and

-the lymphatic and

-nerve supply

Area betn the lungs is the mediastinum occupied by the heart, great vessel, trachea,

right and left bronchi, oesophagus, lymph nodes, lymph vessels and nerves


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The Right Lung:

Has 3 lobes: superior, middle, and inferior

separated by horizontal and oblique fissures

Organization of the Lungs:

The Left Lung: It is smaller as the heart is situated left of the midline

Has 2 lobes:

superior and inferior

are separated by an oblique fissure


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Pleura and Pleural Cavity:

Pleura consists of a closed sac of serous membrane which contain

small amount of serous fluid

Lung is invaginated into this sac so that it forms two layers:

One adheres to the lung and other to the wall of thoracic cage

The Visceral Pleura: adherent to the lung

The Parietal Pleura: adherent to the inside of the chest wall &

the thoracic surface of the diaphragm

The Pleural cavity: Two layers of pleura are separated by only

a thin film of serous fluid,

1.which allows them to glide over each other

2. prevent friction between them during breathing

Serous fluid is secreted by the epithelial cells of the serous membrane


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Interior of the Lung:

composed of the bronchi and smaller air passages, alveoli, connective

tissue, blood vessels, lymph vessels, nerves.

Pulmonary blood supply: pulmonary artery divides into two, one

branch conveying deoxygenated blood to each lung

Within the lungs,

Walls of the alveoli and capillaries each consist of only one layer offlattened epithelial cells

Exchange of gases between air in the alveoli and blood in the

capillaries takes place across this two very fine membranes

The Pulmonary capillaries join up and become two pulmonary veins

in each lung,

Which leave the lungs at hilum and convey oxygenated blood to the

left atrium of the heart


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Relationship between Lungs and Heart

Figure 238

i i


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Refers to 2 integrated processes:

external respiration

internal respiration

External Respiration

Includes all processes involved in exchanging O2 and CO2 with

the environment

Internal Respiration

Also called cellular respiration

Involves the uptake of O2 and production of CO2 within individual

cells

Respiration

Inflation and deflation of the lungs with each breath ensures that

regular exchange of gases


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Muscles of respiration:

In normal breathing,

Intercostal muscles and diaphragm

During difficult or deep breathing,

They are assisted by the muscles of neck, shoulders and abdomen

Intercostal muscles:11 pairs of muscles that occupy the spaces between the 12 pairs of ribs

Arranged in two layers,External And Internal Intercostal Muscle


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The first rib is fixed, therefore, when intercostal muscles contract

they pull all the ribs towards first rib

Bcoz of the shape they move outward, when pulled upward

In this way thoracic cavity enlarged anteriorly, posteriorly and

laterally

Intercostal muscles are stimulated to contract by intercostal nerves

Diaphragm


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Diaphragm

Dome shaped structure separating the thoracic and abdominal cavities

forms the floor of the thoracic cavity and roof of the abdominal cavity

It consist of central tendon from which muscle fibres radiate to be attached tothe lower ribs and sternum

It is supplied by the Phrenic nerves

When the muscle of diaphragm,

Relaxed Contracts

central tendon is at the level

8th thoracic vertebra 9th thoracic vertebra

(muscle fibre shortens, central

tendon pulled downwards)

Enlar in the thoracic cavit

decreases pressure in the thoracic cavity

and increases it in the abdominal and

pelvic cavities

Intercostal muscles & diaphragm

contract simultaneously ensure

enlargement from all side

Cycle of respiration:


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Cycle of respiration:

This occur 12 to 15 times per minute and consists of three phases:

Inspiration Expiration Pause

I i i i f h i i i d


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Inspiration: capacity of thoracic cavity increased

by simultaneous contraction of both muscles

Parietal pleura moves with the walls of thoraxand the diaphragm

Reduces pressure in the pleural cavity than atmospheric pressure

Visceral pleura follows parietal pleura &

pulling lung with it

Stretches the lungs & the pressure within alveoli fall down

in order to equalize atm. & alveolar pressure


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Expiration: Relaxation of the both muscles results in

Downward and inward movement of rib cage &

elastic recoil of lungs

Pressure inside the lungs exceeds that in the

atmosphere

And therefore air is expelled

Inspiration Expiration

active process passive process

Requires expenditure of energy not require


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Blood flow

to alveolus

Blood flow

from alveolus

PO2 100 mm Hg

PCO2 40 mmHg

Atmospheric Air

PO2 40 mm Hg

PCO2 44 mmHg

PO2 100 mm Hg

PCO2 40 mmHg

Blood Capillary

Pulmonary

Artery

Pulmonary

Vein

Fig. External Respiration : Exchange of gases between alveolar air

and capillary blood


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CO2

O2

Diffusion of Co2

Blood Flow

Diffusion of O2

Cells

Tissue fluid

Venous end of

capillary

Fig. Internal respiration : exchange of gases betn capillary and tissues


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Transport of gases in the blood stream:

Transport of blood oxygen and Carbon dioxide necessary for

internal respiration

Oxygen: present with heamoglobin 98.5%

present in plasma water 1.5 %

Dissociates from these

Factors of dissociation: increased CO2 level in tissue fluid,

raised temp., 2,3- diphosphoglycerate present in RBC

In active tissues increased production of CO2 and heat

leads to increase release of oxygen

Carbon dioxide: waste product of metabollism

1. In the form of bicarbonate ions in the plasma 70 %

2. In the plasma 7%, 23 % heamoglobin


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Control of respiration

The respiratory center

Chemoreceptors

Peripheral receptors

Heiring-Breur reflex

Other factors: singing, speeking,

laughing, crying, sneezing and other

environmental factors

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6 the Respiratory System

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