Respiratory System

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  • Created by: kyrag94
  • Created on: 25-04-24 12:27

Organs of Respiratory System

-Larynx connects to pharynx + the trachea

-contains thyroid cartilage, epiglottis, cricoid cartilage, arytenoid cartilages, false vocal cords + true vocal cords

Upper Respiratory tract 

-NOSE - TRACHEA

Lower Respiratory Tract

- TRACHEA - ALVEOLI

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Conducting Zone

- Nose

-Phraynx

-Larynx

-Trachea

-Bronchi

-Bronchioles

Collectively these structures form a continuous path for air to move in and out of lungs

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Respiratory Zone

-Deep inside the lungs

-Respiratory broncioles

-Aleveolar Sacs

-Alveolar ducts

SITE OF GAS EXCHANGE

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Anatomy of the Chest

12 thoracic vertebrae

- T1- T12 situated between neck + lumar vertebrae

-provide attachment for ribs

Sternum (breast bone)

-manubium

-Body

-Metasternum

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Ribs

-12 pairs of ribs

True ribs = 1-7

-connected directly to sternum by strips of cartilage

False Ribs= 8-10

- Not directly connectef to the sternum but connected to lowest true rib

Floating ribs= 11-12

- Attached to the spine 

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Anatomy of the Chest

Thoracic cavity divided into 2 pulmonary cavities

A lung is contained inside each 

- separated by the mediastinum

- each lung covered with 

  • Inner lining called visceral pleura
  • Outer lining called parietal pleura

These 2 layers are separated by the pleural cavity

Pleural Cavity

-space between visceral + parietal layers

-filled with serous fluid (pleural fluid)

-Fluid helps prevent cavity from collapsing (excess fluid= pleural effusion)

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Pharynx + Larynx

Pharynx (the throat)

- about 12 cm long behind nasal cavities

- mouth connects them to larynx + oesophagus

Larynx (voicebox)

-extends from 4th to 6th cervical vertebrae

-attaches hyoid bone superiorly

-inferiorly continuous with trachea

-Produces vocalisations (speech)

-Provides open airways (breathing)

-Switching mechanism into proper channels closed during swallowing open during breathing

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Trachea

- extends from larynx to the primary bronchi

-composed of smooth muscle + c-shaped cartilage rings + is lined with pseudostratified cillated columnar epithelium

-bronchi tree consists of trachea, primary bronchi, secondary bronchi, tertiary bronchi, bronchioles + terminal bronchioles

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Lungs

-paired organs in thoracic cavity

-enclosed by pleural membrane

-parietal pleura is outer layer

-viseral pleura is inner layer

-right lung has 3 lobes separated by 2 fissures

-left lung has 2 lobes separated by 1 fissure plus a depression (cardiac notch)

-each lobe has lobules which contain lymphatic vessels, arterioles, venules, terminal bronchioles, respiratory bronchioles, alveolar ducts, alveolar saccs and alveoli

-Helium= connects lungs to their supporting structure + where pulmonary vessles enter + exit

-exchange of gases in lungs occurs across a respiratory membrane consisting of alveolar cells, basement membrane + epithelial cells of a capillary

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Bronchial Tree

Trachea

Primary bronchi

Secondary bronchi

Tertiary Bronchi

Broncioles

Terminal Bronchioles

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Microscopic airways

Terminal Bronchioles

Respiratory Bronchioles

Alveolar Ducts

Alveolar Sacs

Alveoli

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Functions

- provides for gas exchange

-intakes O2 for delivery to cells

-removes CO2 produced by cells

-helps regulate blood pH

-contains receptors for sense of smell, filters inspired air, produces sound + excretes small amounts of water + heat

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Pulmonary Ventilation

-movement of air in and out of lungs

-air flows from hgher to lower pressure

Inspiration = air in 

Expiration= air out

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Inhalation

-occurs when alveolar pressure falls below atmospheric pressure

-contraction of the diaphragm (flattens) + external intercostals expands lung volume

-ribs move up + out

-increased volume of lungs decreases alveolar pressure

- Air moves from higher pressure to lower into the lungs

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Exhalation

- occurs when alveolar pressure is higher than atmospheric pressure

-contraction of diaphragm (curved again) + external intercostals decreased lung volume

-Alveolar pressure increases so air moves out

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Forced Inhalation

-sternocleidomastids, scalenes + pectorals minors contribute to forced inhalation

-forced inhalation involved contraction of internal intercostals, external + internal oblique, transverse + rectus abdominals

-low compliance= stiff lung

- high compliance= pilable lung (elastic recoil low)

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Lung Volumes + Capacities

Tidal Volume- volume of air inspired or expired during 1 single resp

Expiratory reserve volume- amount of air that can be voluntarily expelled at the end of tidal volume

Inspiratory reserve volume- amount of air that can be taken in over + above tidal volume

Vital capacity- maximum amount of air in/out of lungs in 1 resp

Spirometry | OSCEstop | OSCE Learning

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Surfactant

-type II cubodial epithelial cells are scattered in alveolar sacs

-surfactant is a detergent like substance which is secreted in fluid coating alveolar surfaces

-decreases surface tension

-without it the walls would stick together in lungs

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Tissue changes

Primary Bronchi down to terminal broncioles

-Cartilage plates decreases

-Smooth muscle increases as cartilage decreases

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Gaseous Exchange

External Respiration

-exchange of gases between alveolar air + pulmonary blood capillaries

-aided by a thin respiratory membrane

-large surface area

-rich blood supply

-oxygen pressure high in alveoli but low in blood so moves

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Gaseous Exchange

Internal Respiration

-exchange of gases between systemic tissues, capillaries + cells

-partial pressure gradient of oxygen is low gas moves from high pressure to low

-oxygen disassociates from haemoglobin

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Transportation of Gases

Oxygen

-1.5% is dissolved in blood plasma

-98.5% carried by iron ions of the heme in haemoglobin (oxyhaemoglobin)

-Associationof O2 + haemoglobin is affected by pressure + temperature

Carbon Dioxide

-7% dissolved in plasma

-23% combines with haemoglobin 

-70% as biocarbonate ions (HCO3-) 

- Helps regulate blood pH

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Control of Respiration

-respiratory centre consists of medullary rhythmicity area (inspiratory + expiratory areas) in the medulla obolongata

- groups of neurones in the pons (pneumotoxi area + apneutic area)

-inspiratory area sets basic rhythm of respiration

- respirations can be modified by serveral factors

  • chemical stimuli (levels of O2, CO2 and H+)
  • limbic system stimulation
  • proprioceptor inout
  • temperature
  • pain
  • inflatation reflex
  • irritation to airways
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Neural Control of Ventilation

- recticular formation in medulla is responsible for basic rate + rhythm

-modified by certain centers

- chemoreceptors (central in medulla)

-Peripheral(aortic bodies on aortic arch, carotid bodies at fork of carotid artery monitor O2 + CO2 tension in blood

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