Respiratory System Flashcards
Function of respiratory system
Gas exchange Regulates blood pH Contains receptors for sense of smell Filters inspired air Produces sounds Rids body of some water & heat in exhaled air
Cooperates with the cardiovascular system to supply O2 & eliminate CO2
Respiration
- Brings in oxygen and ridding body of carbon dioxide
- Nose filters the dust and microbes, from entering the system
- Voice production (voice box houses vibrations on strings, as air moves up and down. Mouth & tongue allows speech).
- pH regulation: by eliminating carbon dioxide. CO2 changes the hydrogen-ion concentration of your blood. CO2 can combine with H2O to become H2CO3 (carbonic acid, unstable so immediately decomposes into ions. Extra H+ will lower your pH. The lower the pH the greater acidity it has)
- Smell , receptors in the upper nose, ‘olfaction’ is a sense of smell.
- thermo regulation through lungs expelling air
Upper Respiratory System
Nose
Pharynx = throat
Lower Respiratory System
Larynx = voicebox / vocal chords (continues as a pipe, carrying air to the trachea).
Trachea = windpipe (one single pipe)
Bronchi = airways
Lungs (Two lungs so tranchea splits into two tubes - called Bronchi (singular is brochus)
Conducting zone – series of interconnecting cavities & tubes
Nose, pharynx, larynx, trachea, bronchi, bronchioles & terminal bronchioles
Respiratory zone – tissues where gas exchange occurs between air & blood
Respiratory bronchioles, alveolar ducts, alveolar sacs & alveoli
pharynx
throat
larynx
voicebox / vocal chords
trachea (windpipe)
- Tubular passageway for air
- 12cm long & 2.5cm in diameter
- Extends from larynx to T5
- Located anterior to oesophagus
- At T5 level splits into left & right primary bronchi
- Composed of 4 layers
bronchi
airways
alveoli
lungs
Trachea (windpipe) layers
Four layers:
- Mucosa: pseudostratified columnar with cilia & goblet
- Submucosa: loose connective tissue & mucous glands
- Hyaline cartilage: 16 to 20 incomplete rings (C-shaped). Open side facing esophagus contains trachealis muscle (smooth). Internal ridge on last ring called carina
- Adventitia - binds it to other organs
The Bronchial Tree
- Primary bronchi supply each lung
- Secondary (lobar) bronchi supply each lobe of the lungs (3 right + 2 left)
- Tertiary (segmental) bronchi supply each bronchopulmonary segment
- The smallest bronchioles branch into even smaller branches called terminal bronchioles
- Repeated branchings called bronchioles form a bronchial tree
What cells are the bronchi made of?
Bronchi is made of pseudostratified ciliated columnar
What are the epithelial tissue changes in the bronchial tree?
Epithelial tissue changes in the bronchial tree:
- Larger bronchioles = ciliated simple columnar with goblet cells
- Smaller bronchioles = ciliated simple cuboidal with no goblet cells
- Terminal bronchioles = nonciliated simple cuboidal - in these regions inhaled particles are removed by macrophages
Visceral pleura
The visceral pleura covers lungs
Parietal pleura
The parietal pleura lines ribcage & covers upper surface of diaphragm
Where is the pleural cavity?
Pleural cavity in between parietal pleura and the visceral pleura. The pleura cavity reduces friction between the two as there is a fluid present (which can increase / decrease in amount, which can affect breathing (asthma). Pleural effusion
Alveoli of the Lung
Alveoli of the lung
- Cup-shaped outpouchings surrounding alveolar ducts
- Lined by simple squamous epithelium & supported by thin elastic basement membrane
- Two or more alveoli make up alveolar sacs
Cells Types of the Alveoli
- Type I alveolar cells: simple squamous cells where gas exchange occurs.
- Type II alveolar cells (septal cells): free surface has microvilli, secretes alveolar fluid containing surfactant.
- Alveolar dust cells: wandering macrophages remove debris
Bronchopulmonary Segements of the Lung
Bronchopulmonary Segements of the Lung are:
- Comprised of small compartments called lobules
- Each lobule is wrapped in connective tissue
- Contains lymphatic vessel, arteriole, venule & branch from terminal bronchiole
- Terminal bronchioles
- > microscopic respiratory bronchioles ->alveolar ducts (2-11)
Bronchopulmonary Segements of the lung have their own airways, blood supply & venous structure – so you can take it out without affecting the overall functioning of the lungs.
Important of surfactant and surface tension
Surface Tension
> Inwardly directed force caused by thin layer of alveolar fluid (water molecules stronger attracted to each other than to air)
> Causes alveoli to remain as small as possible
Surfactant produced by Type II alveolar cells > lowers alveolar surface tension
What are the three basic steps of respiration?
- Pulmonary ventilation (breathing)
- Inhalation (inflow) & exhalation (outflow)
- Air exchange between atmosphere & alveoli - External (pulmonary) respiration
- Gas exchange across respiratory membrane between alveoli & blood in pulmonary capillaries - Internal (tissue) respiration
- Gas exchange between blood in systemic capillaries & tissue cells
Blood Supply to the Lungs
- Deoxygenated blood arrives through pulmonary trunk from the right ventricle
- Four pulmonary veins return oxygenated blood to the left atrium
- Bronchial arteries branch off of the aorta to supply oxygenated blood to lung tissue
- Pulmonary blood vessels constrict in response to low O2 (hypoxia). Ventilation – perfusion coupling
Boyle’s Law
Increase in volume, decrease in pressure. Increase in pressure, decrease in volume.
Inverse relationship between volume & pressure
Compliance of the Lungs
Ease with which lungs & chest wall expand. Compliance can be high or low
depending onelasticity of lungs & surface tension.
Some pulmonary conditions reduce compliance
What is the breathing patter, eupnea?
Eupnea = normal quiet breathing
What is the breathing pattern, apnea?
Apnea = temporary cessation of breathing
What is the breathing pattern, dyspnea?
Dyspnea =difficult or labored breathing
What is the breathing pattern, tachypnea?
Tachypnea = rapid breathing
What is the breathing pattern, diaphragmatic breathing?
Diaphragmatic breathing = descent of diaphragm causes stomach to bulge during inspiration
What is the breathing pattern, coastal breathing?
Costal breathing = just rib activity involved
Quiet Inspiration
During quiet inspiration only the diaphragm contracts (ribs lifted by muscles)
Quiet Expiration
Diaphragm relaxes, no muscles engaged.
Forced / laboured inspiration
Forced inspiration: sternocleidomastoid, scalenes & pectoralis minor lift chest upwards as you gasp for air
Forced/laboured expiration
Forced expiration: abdominal mucles force diaphragm up and internal intercostals depress ribs
From primary bronchi through to distal bronchioles (in addition to epithelium changes) there are connective tissue, ie. cartilage, changes in the bronchial tree.
- Plates of cartilage gradually replace incomplete rings of cartilage & finally dissapear
- Cartilage becomes replaced by smooth muscle & connective tissue
- Smooth muscle encircles lumen in spiral bands
- Muscle spasms can close off the airways
Lung volume & capacities
X
Factors that affect hemoglobin (Hg) affinity for oxygen (O2)
- Oxygen partial pressure
↑ PO2 -> ↑ binding of oxygen - Acidity
↑ Acidity (↓pH) -> ↓ O2 affinity (more O2 is unloaded); known as Bohr effect
Note: ↓ acidity -> ↑ O2 affinity - CO2 partial pressure
↑ PCO2 -> more acidic environment –> ↑
O2 release from Hb - Temperature
↑ temperature -> ↑ O2 release from Hb - BPG
↑ BPG -> ↑ O2 release from Hb
Daltons Law, how it affects movement of things in and out
- Each gas in a mixture of gases exerts its own pressure, partial pressure (Px)
- Total pressure of mixture is sum of all partial pressures. Atmospheric pressure (760 mm Hg) = PO2 PN2 + PH20 + PCO2
Eg: to determine partial pressure of O2 in the atmosphere - multiply 760 by % of air that is O2 (21%) = 160 mm Hg
Partial pressures determine the movement of O2 and CO2 between
- Atmosphere & lungs
- Lungs & blood
- Blood & body cells
Each gas diffuses across permeable membranes from areas where its partial pressure is greater -> areas of lesser partial pressure
Henry’s Law
- Amount of gas dissolving in a liquid is proportional to the partial pressure of the gas & its solubility
- Ability of gases to stay in solution in body fluids is greater with higher partial pressure & higher solubility in water
- Solubility of some gases at sea level pressure
CO2 > O2 > N2
E.g.: CO2 in soft drinks
Note: ↑ total air pressure → ↑ partial pressure of all its gases.
For things to diffuse, it needs to dissolve in the plasma membrane, the higher the solubility the higher (and quicker) the diffusion. Carbon Dioxide is the more soluble than oxygen.
Tidal volume (VT)
Total volume of one breath at rest: inhalation + exhalation
Minute ventilation (MV)
- Total volume of air moved each minute = repiratory rate × tidal volume
- Healthy adult: 12breath/min × 500ml/breath = 6liters/min
Inspiratory reserve volume
Inspiratory reserve volume is a lung volume measured relative to forceful breathing. Inspiratory reserve is the air a person can inhale in addition to 500ml of Tidal volume
Expiratory reserve volume
Expiratory reserve volume is a lung volume measured relative to forceful breathing. Inspiratory reserve is the air a person can exhale in addition to 500ml of Tidal volume
Residual volume
Volume of permanent trapped air in the system
Cannot be measured by spirometry
Minimal Volume
Remaining air after thoracic cavity is opened
Henry’s Law - an condition resulting from changes in N2 solubility when scuba diving
Diving deep → ↑ pressure forces more N2 to dissolve in the blood (nitrogen narcosis). When you dive deep the nitrogen gets dissolved.
When you dive and come up too quickly nitrogen comes out of solution too quickly
(decompression illness)
These things dictate diffusion
Partial pressure differences in the gas.
Surface area available for gas exchange.
Distance to which things have to travel
Molecular weight and solubility of gases
Oxygen transport in blood
Each 100mls of oxygenated blood contains
- 1.5% of O2 dissolved in blood plasma, which can easily diffuse out of capillaries into tissue cells
- 98.5% of O2 bound to hemoglobin as oxyhemoglobin (Hb-O2) trapped inside Red Blood Cells (RBC)
Carbon Dioxide Transport
100 ml of deoxygenated blood contains 53 ml of gaseous CO2
Transported in blood in 3 ways:
- 7% dissolved in plasma
- 23% combined with the globin part of Hb molecule forming carbaminohemoglobin
- 70% in plasma as part of bicarbonate ions - HCO3-
Role of the Respiratory Center
The lungs do not control respiration.
Respiration is governed by respiratory centre – controls depth and rate of breathing.
Respiratory Center functions on its own however it can be influenced by certain receptors.
