Respiratory System
- 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
Conducting Zone
- Nose
-Phraynx
-Larynx
-Trachea
-Bronchi
-Bronchioles
Collectively these structures form a continuous path for air to move in and out of lungs
Respiratory Zone
-Deep inside the lungs
-Respiratory broncioles
-Aleveolar Sacs
-Alveolar ducts
SITE OF GAS EXCHANGE
Anatomy of the Chest
12 thoracic vertebrae
- T1- T12 situated between neck + lumar vertebrae
-provide attachment for ribs
Sternum (breast bone)
-manubium
-Body
-Metasternum
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
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)
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
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
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
Bronchial Tree
Trachea
Primary bronchi
Secondary bronchi
Tertiary Bronchi
Broncioles
Terminal Bronchioles
Microscopic airways
Terminal Bronchioles
Respiratory Bronchioles
Alveolar Ducts
Alveolar Sacs
Alveoli
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
Pulmonary Ventilation
-movement of air in and out of lungs
-air flows from hgher to lower pressure
Inspiration = air in
Expiration= air out
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
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
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)
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
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
Tissue changes
Primary Bronchi down to terminal broncioles
-Cartilage plates decreases
-Smooth muscle increases as cartilage decreases
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
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
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
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
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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