EAC Respiratory System Flashcards by s d

respiratory systems four specific functions

Extract oxygen from the atmosphere and transfer it to the blood stream

excrete water vapour and Co2

Maintain acid base status of the blood

Ventilate the lungs

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components of inspired air

O2 = 20%
Nitrogen = 79%
Inert gasses = 1%
Carbon dioxide = 0.04%
Water vapour (variable)

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components of expired air

O2 = 16%
Nitrogen = 79%
Inert gases = 1%
Carbon dioxide = 4%
Water vapour (to saturation)

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structure and function of:

Nasal cavity

The nasal cavity is a hollow space within the nose and skull that is lined with hairs and mucus membrane. The function of the nasal cavity is to warm, moisturize, and filter air entering the body before it reaches the lungs.

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structure of:

Pharynx

The area of the respiratory tract behind the nasal and oral cavity extending down as far as the cricoid cartilage of the larynx. Its lined with mucous membrane and is composed of skeletal muscle.

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functions of:

Pharynx

act as a passageway for air, food and water.

Is a resonating chamber for speech sounds.

Houses the tonsils.

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three parts of the pharynx are:

nasopharynx - behind nasal cavity superior to the soft palate

oropharynx - extends from level of soft palate to level of hyoid bone

laryngopharynx - starts at the level of the hyoid bone leading to the oesophagus and the larynx

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structure of:

Larynx

connects laryngopharynx with the trachea

lies in mid line of neck anterior to 4th - 6th cervical vertebrae (C4,5,6)

consists of Hyoid bone, thyroid cartilage and cricoid cartilage

there are 3 single cartilages (thyroid, epiglottis and cricoid)

there are also 3 paired cartilages (arytenoid, cuneiform and corniculate)

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functions of:

Larynx

Production of sound

Speech

Protection of the lower respiratory tract during swallowing

Provide passageway for air from the pharynx to the trachea

Continues the process of humidifying, filtering and warming inspired air

in swallowing as the larynx rises the free edge of the epiglottis descends shutting of the respiratory tract preventing food, drink, secretions etc. from entering. Directing them down the gastrointestinal tract. should they pass into the larynx this stimulates the cough reflex which expels them from the respiratory tract.

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structure and function of:

Epiglottis

Large piece of elastic cartilage attached to anterior rim of thyroid

It is leaf shaped

The leaf like portion is unattached and moves up and down like a trap door

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structure and function of :

Thyroid

Forms anterior wall of the larynx and gives it its prominence

Connected to the hyoid bone by the thyrohyoid membrane

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Structure of:

Trachea

Composed of 16-20 incomplete C shaped rings of cartilage that lie on top of each other. Providing semi-rigid support to trachea wall so that with changes of air pressure it does not collapse.

Incomplete part of C faces oesophagus

Extends from Larynx to the level of 5th thoracic vertebrae (T5)

Approx. 12cm long and 2.5cm diameter

Inner layer lined with ciliated columnar epithelium containing goblet cells

terminates at the Carina, formed by the last C shaped ring at the level of T5, dividing into left and right primary bronchus.

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Function of:

Trachea

Support and Patency

Mucociliary escalator

Cough reflex

Warming, humidifying and filtering air

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structure of:

Bronchus/Bronchi and Bronchioles

The right primary bronchus is more vertical, shorter and wider then the left. An aspirated object is therefore more liable to enter the right primary bronchus.

Primary bronchi divide to form smaller secondary (lobar) bronchi

Secondary bronchi branch off forming smaller tertiary bronchi

tertiary bronchi divide into bronchioles

bronchioles branch repeatedly until they’re minute, termed ‘Terminal bronchioles’

this branching from the trachea is commonly referred to as ‘the bronchial tree’

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structure changes as The Bronchial Tree extends

epithelium changes from pseudo-stratified ciliated columnar epithelium in bronchi to non ciliated simple cuboidal epithelium in terminal bronchioles

incomplete rings of cartilage in primary bronchi are gradually replaced by plates of cartilage that finally disappear

as the amount of cartilage decreases the amount of smooth muscle increases

smooth muscle encircles the bronchioles in spiral bands

dilation of this muscle will increase bronchiolar diameter

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function and structure of:
Alveolar ducts and Alveoli

Terminal bronchioles - respiratory bronchioles - alveolar ducts

alveolar ducts end in the air sacs/Alveoli

gas exchange can only take place in the Alveoli and walls of alveolar ducts

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Structure of:

Lungs

the lungs are 2 coney shaped, spongy organs situated either side of the mediastinum within the thoracic cavity

the right has 3 lobes and the left 2 lobes

has an apex, base, costal surface and medial surface

All structures enter the lung at the hilum on the medial surface

the lungs and the interior of thoracic cavity are lined by serous membrane (the pleura/pleural membrane)

thoracic cage firmly attached to and lined by parietal pleura

lungs enclosed and protected by visceral pleura

the two layers are in close contact during normal health separated by a thin film of serous fluid

between the two layers is the pleural cavity, filled with serous fluid to reduce friction allowing them to slide easily over one and other during breathing

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blood supply to the lungs

the blood supply to the lungs is a double circulation:

pulmonary circulation

Systemic circulation

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define:

Pulmonary circulation

that which takes part in respiration. the pulmonary trunk (from RV) splits into left and right pulmonary arteries containing de-oxygenated blood. Gaseous exchange takes place and oxygenated blood goes through the venous side of the pulmonary circulation

define:

Systemic circulation

That which provides blood to the lung as an organ. Particularly the bronchi and bronchioles. This circulation returns either to the superior vena through its own venous network or by connections between bronchial and pulmonary arteries

mechanics of Ventilation

the process of gases being exchanged between the atmosphere and alveoli

the pressure inside the alveoli with respect to atmosphere is changed by changes in the size of the lungs

during inspiration air pressure is less than atmospheric and air is drawn into lungs

during expiration pressure within lung rises to above atmosphere and air is expelled from the lungs

mechanics of Ventilation:

Diaphragm

the diaphragm in its relaxed form is dome shaped. when it contracts is flattens which increases the size of thoracic cavity causing pressure to fall.

inspiration is initiated by the phrenic nerve originating from the cervical spine at c3, c4, c5 (c3,4 and 5 keep the diaphragm alive)

mechanics of Ventilation:

Inspiration

muscles in ribs contract and pull cage upwards and outwards. altering the shape of the rib cage.

diaphragm pulls downwards and flattens out. Increasing the size of the thoracic cavity.

atmospheric pressure rises to above Intrathoracic pressure and air is drawn into the lungs from the atmosphere.

inspiration is initiated by the phrenic nerve originating from the cervical spine at c3, c4, c5 (c3,4 and 5 keep the diaphragm alive)

mechanics of Ventilation:

expiration

diaphragm relaxes and reverts to dome shape reducing size of thoracic cavity.

intercostal muscles relax bringing the rib cage downwards and inwards reducing size of thoracic cavity.

Intrathoracic pressure then rises to above atmospheric and air is expelled from lungs into atmosphere.

define: | Anatomical Dead Space

in normal quiet breathing the lungs and air passages are never empty. Gaseous exchange can only take place in the Alveolar ducts and the alveoli. The remaining capacity of the respiratory passages, where gaseous exchange cannot take place, is termed the anatomical dead space (about 150mL)

define: | Tidal Volume

This is the amount of air passing into and out of the lungs during each cycle of normal quiet breathing (about 500mL at rest)

define: | Minute Volume

Minute volume = tidal volume X breathing rate per minute

define: | diffusion

the movement of molecules from and area of high concentration to an area of low concentration, down the concentration gradient, until all areas are of equal concentration

define: | Internal Respiration

the exchange of gases (as oxygen and carbon dioxide) between the cells of the body and the blood by diffusion

define: | External Respiration

the exchange of gases between the external environment and the blood by diffusion in the lungs between the alveoli and the blood due to changes between atmospheric pressure and the pressure in the thoracic cavity

Describe how respiration is controlled: | voluntary control

exerted during speaking, singing, holding breath. the centre for this control is in the cerebral cortex (outer layer of the brain) it can be overridden by a rising level of paCo2 and acidity causing involuntary respiration

Describe how respiration is controlled: | involuntary control - inspiration

the respiratory centre is in the Medulla Oblongata. It is concerned with inspiration. nerve impulses pass vie the phrenic nerve to the diaphragm and via intercostal nerves to the intercostal muscles. Resulting in contraction of these muscles and therefore inspiration

Describe how respiration is controlled: | involuntary control - expiration

the Pneumotaxic Centre is in the Pons Varolli receives impulse from nerve endings in the lungs sensitive to stretch, stimulated when the lungs are inflated. causing expiration to occur.

define: | acid base balance

the regulation of hydrogen ions (H+) in body fluid and the maintenance of balance between acid and alkaline. the number of H+ in a solution is a measure of its acidity. unit of measurement is pH (the power of hydrogen)

Respiration Rates

0-12months 30-40BreathsPM 1-2yrs 25-35BPM 2-5yrs 25-30BPM 5-11yrs 20-25BPM Adult 12-20BPM

define: | Dyspnea

difficult or laboured breathing.

define: | Apnea

cessation of respiration

define: | Hypoxia

deficiency in the amount of oxygen reaching the tissues

define: | Hypercarbia

More than the normal level of carbon dioxide in the blood

Describe how respiration is controlled: | involuntary control

Chemo Receptors - in the respiratory centre (central chemo receptors) and in arterial walls (peripheral chemo receptors) central chemo receptors respond to PCO2 rises increasing ventilation and reducing PCO2. peripheral chemo receptors found in the arch of aorta and in the bifurcation of common carotids on each side. They respond to changes in blood CO2 and O2 levels. Even a slight CO2 level rise activates these receptors by impulses sent to respiratory centre via Glossopharyngeal and Vagus nerves. This stimulates an immediate rise in rate and depth of respiration. An increase in blood acidity also stimulates them resulting in increased ventilation, increasing CO2 excretion and increasing blood ph. They also help regulate blood pressure

lung volumes: | Inspiratory Reserve Volume IRV

the extra volume of that can be inhaled into the lungs during maximal inspiration

lung volumes: | Inspiratory Capacity IC

this is the amount of air that can be inspired with maximum effort. it consists of TV (500ml) plus the IRV

lung volumes: | Functional Residual Capacity FRC

This is the amount of air remaining in the air passages and alveoli at the end of quiet expiration. Tidal air mixes with this air, causing relatively small changes in the composition of alveolar air. as blood flows continuously through the pulmonary capillaries, this means exchange of gasses is not interrupted between breaths, preventing moment to moment changes in blood gases. The functional residual volume also prevents collapse of the alveoli on expiration.

lung volumes: | Expiratory Reserve Volume ERV

This is the largest volume of air that can be expelled form the lungs during maximal expiration.

lung volumes: | Residual volume RV

this cannot be directly measured but is the volume of air remaining in the lungs after forced expiration

lung volumes: | Vital Capacity VC

this is the maximum volume of air that can be moved into and out of the lungs. VC = TV + IRV + ERV

lung volumes: | Total Lung Capacity TLC

This is the maximum volume of air the lungs can hold. In an adult of average build, it is normally around 6 litres