PHTY 142 Respiration Flashcards
anatomical position of the lung
diaphragm to clavicles
lie against ribs anteriorly and posteriorly
base is concave and fits over the convex diaphragm
Apex is upwards above the 1st rib and into floor of the neck
What is the hilum
Medial surface of each lung
bronchi, blood and lymphatic vessels , nerves enter or exit
Held together by pleura and connective tissue
Cardiac notch
Located in the left lung medially
Where the apex of the heart lies
Due to heart - left lung is 10% smaller than right
Differences between the right and left lung
right - 3 lobes
Left - 2 lobes
Right - 2 bronchi
Left - 1 bronchus
Right - heavier
Right - shorter and wider
Left - long and narrow
Right provides space for liver
Left provides space for the heart
How to fissures separate lobes
Both lungs have oblique fissures
They extend inferiorly to anteriorly
Left - Separates inferior and superior lobe
Right has Horizontal fissure
Right - Oblique fissure superiorly separates inferior lobe from superior lobe
Inferiorly the oblique fissure separates inferior lobe form the middle lobe
Middle lobe is bordered superiorly by the horizontal fissure
Lobes in right and left lung
Right:
Superior, inferior and middle
Left:
Superior and inferior
Airways that supply lobes
Each has lobar bronchus
Right - 3, the superior, inferior, middle lobar bronchus
Left - 2, The superior and inferior lobar bronchus
Segments in the lung
There are 10 Segmental (tertiary) bronchi in each lung
Each portion of tissue that the segmental bronchi supplies is called Bronchopulmonary segments
What does the Hilum consist of
Bronchi
Pulmonary artery and vein
Nerves
Lymph nodes and lymphatic vessels
Pulmonary ligament
The 2 pleura
Parietal pleura
Superficial layer
Lines wall of thoracic cavity
Visceral pleura
Deeper layer
Covers lungs
What is the pleural cavity
Space between pleura
Contains lubricating fluid
Reduces friction between membranes allowing the membranes to slide over each other
Muscles involved in quiet inspiration
Diaphragm - flattens increases thoracic volume and lowering pressure. 75% of the energy
Abdominal wall relaxes - abdominal contents displaced
Intercostals are involved - forward movement of sternum and upward&outward movement of ribs
Muscles involved in quiet expiration
No direct muscle action
During inspiration lungs expand against elastic recoil which is sufficient to drive air out
Expiration : Controlled relaxation of intercostal muscles and diaphragm
Muscles involved in forced expiration
diaphragm
Scalene muscles and sternocleidomastoids (accessory muscles) raise ribs
Intercostal muscles
quadratus lumborum - force downward movement of diaphragm
Erector spinae
Muscles for Forced expiration
muscles of abdominal wall to move diaphragm
Quadratus lumborum
intercostal muscles prevent deformation of tissue
Use of accessory muscles – respiratory distress
Surface anatomy of the lung
Apex - medial third of the clavicles
lower borders - T6, T8, T10
Tidal Volume
Volume of air breathed in and out in a single breath
0.5L
Inspiratory reserve volume
Expiratory reserve volume
Volume of air breathed in by maximum inspiration at end of normal inspiration
Volume of air that can be expelled by a maximum effort at the end of normal expiration
Residual Volume
Volume of air remaining in lungs at the end of maximum expiration
Not measured using spirometry
Inspiratory capacity
Volume of air breathed in by maximum inspiration at the end of normal expiration
Tidal Volume + Inspiratory reserve volume
Functional residual capacity
Volume of air remaining in the lungs at the end of normal expiration.
Expiratory reserve volume + residual volume
Not measured using spirometry
Vital Capacity
Volume of air that can be breathed in by maximum inspiration following maximum expiration
Inspiratory reserve volume + Tidal volume + Expiratory reserve volume
Total Lung capacity
Only a fraction of TLC is used in normal breathing
VC + RV
Functional significance of residual volume
A fully deflated lung requires a lot more energy to inflate
Obstructive disorder
obstruction of normal air flow caused by airway narrowing
Residual volume is increased as gas cannot leave the lung
RV: TLC ratio increases
Severe: Vital capacity can decrease
Example : COPD
Restrictive disorder
Stiffer lungs so cannot expand to normal volumes
subdivisions of volume are decreased
RV:TLC would be normal or increased
Example: Idiopathic pulmonary Fibrosis
FEV1
Forced expiratory volume in 1 second
Volume of air expelled in the first second of forced expiration starting from full inspiration
FVC
Forced Vital Capacity
A measure of total lung volume exhaled with maximal effort after full expiration
FEV1/FVC ratio
FEV1 is 80% of FVC in normal
measure of airway limitation and allows us to differentiate between obstructive and restrictive lung disease
Restrictive: Both FEV1 and FVC are decreased , often in proportion to each other
Obstructive: FEV1 is reduced much more than FVC so the FEV1/FVC ratio is reduced
Respiratory pathway
Mouth/nose
Pharyx
Larynx
Trachea
Bronchi (main, lobar, segmental)
Bronchioles
Lungs
Alveoli
nose
Has external nose and nasal cavities separated by the nasal septum
Lateral wall of nasal cavity: Bony ridges called conchae providing large surface area
Nose - humidifies and warms inspired air
Mucus secreting goblet cells with microvilli propels mucus to the pharynx where it is swallowed
Pharynx
Base of skull to inferior border of cricoid cartilage
Divided into 3 parts: nasopharynx, oropharynx and laryngopharynx
Trachea
Cartilaginous and membranous tube
10cm in length and Extends from larynx to carina
Supported by c shaped rings of hyaline cartilage
Epithelium sits on basement membrane separating it from lamina propria
Lamina propria lies a loose submucosa
Relations: Thyroid gland, carotoid arteries, oesophagus
Bronchus
divided into left and right at the carina
right - shorter and more vertical
Primary bronchi within each lung is divided into secondary or lobar
Fewer goblet cells than the trachea
Bronchiole
no cartilage and rely on parenchymal tissue for support
Surrounded by smooth muscle and have few alveoli so is a site for gaseous exchange
divide up to 20 or more generations before meeting the terminal bronchiole
Terminal bronchiole supplies the end respiratory unit
Alveoli and alveolar duct
Ducts: Rings of smooth muscle, collagen and elastic fibres
Open into 2 or 3 alveolar sacs
Alveoli: Blind ended terminal sac where gaseous exchange occurs
Lined with type 1 and type 2 pneumocytes
Type 1 and 2 pneumocytes
Type 1 : Cover 95% of the internal surface of each alveoli. They share a basement membrane with pulmonary capillary to form a blood brain barrier
Type 2 : Synthesising cells of the alveolar surfactant. It maintains alveolar and airway stability by reducing surface tension
Pore of Kohn
epithelial lined opening s between adjacent alveoli
Usually contain fluid an usually only open in response to high pressure gradient
Between 13-21 pores in each alveolus
Channel of lambert
Communications from respiratory bronchioles to alveolar ducts
Have muscular wall with possible regional airflow control
Channel of Martin
Diameter of 30um
found between respiratory bronchioles and terminal bronchioles
Alveolar macrophage
Most numerous of cells in the lungs
They clear up dust debris through phagocytosis
They are found in the mucociliary escalator
The mucociliary escalator
Deals with large particles trapped in bronchi and bronchioles brought up by alveolar macrophages
Has mucus film which is divided into 2 layers
Periciliary fluid layer about 6um deep – this reduces viscosity and allows movement of cilia
Superficial gel layer about 5-10um deep – viscous layer forming a sticky blanket which traps particles
Superficial gel layer with trapped particles can be continually transported upwards towards the mouth
pathway of MCE
Connective tissue
Cartilage
submucosa
lamina propria
Basement membrane
Cilia
Mucus blanket
How can MCE clearance be inhibited
Smoking
cold air
Drugs like general anaesthetics
Sulphur oxides
Nitrogen oxides
Cough reflex arc
Initiated by cough receptors which send information to afferent nerves. These receptors are found in the trachea, carina, pharynx
Sensory information to NTS of the medulla
Motor neurons to effector muscles
Respiratory muscles contract to allowing cough reflex
Diaphragm flatterns
Laryngeal muscles close vocal cords
E intercostals contract
Rectus abdominus contracts to depress ribcage
3 main phases of the cough reflex
Inspiratory phase
Irritation of cough receptors
Compression phase
epiglottis and Vocal cords close
Expiratory phase
internal intercostals contract to depress thoracic cavity
Vocal cords relax and epiglottis opens
physical defences
Preventing entry
filtering of nose
Prevention of aspiration while swallowing
Cough reflex
mucocililary clearance
Alveolar macrophages
Humoral defences
Antimicrobial peptides
Surfactant
Immunoglobulins
Compliment
Antiproteases
Cellular defence
Alveolar macrophages neutrophils
Process of gaseous exchange
O2 diffuses from alveolar air at 105mmHg to capillaries where PO2 is 40mmHg
O2 diffuses from alveolar air to capillaries CO2 is diffusing in the opposite direction from 45mmHg to 40mmHG
Exhalation keeps CO2 at 40mmHg in alveolar
What influences rate of gas exchange
Partial pressure of gases
Surface area available
Diffusion distance
Molecular weight and solubility of the gases
O2 has lower weight than CO2 but solubility of CO2 is greater. Outward of CO2 faster than O2 in
Oxygen binding to heamoglobin
only 1.5% of O2 inhaled is dissolved in blood plasma
98.5% is bound to heamoglobin
Each RBC contains a heam group with 4 irons
4 molecules of oxygen and bind
Haemoglobin and oxygen partial pressure
The higher the PO2 the more O2 that binds
When reduced heamoglobin is completely converted it is said to be fully saturated
Hb and Hb-O2 mix is partially saturated
How CO2 is transported
Dissolved CO2 - 7% dissolved in blood plasma
Carbamino compounds - 23% combines with amino groups. The main CO2 binding site are terminal amino acids in the two alpha and beta globin chains of haemoglobin
Bicarbonate ions - 70%. As CO2 diffuses into capillaries it reacts with water in the presence of CA enzyme to form carbonic acid
Oxygen dissociation curve
Where PO2 is high like in pulmonary capillaries oxygen saturation is high. High affinity
Where PO2 is low like in tissue capillaries, unloading happens and saturation is less. Low affinity
Factors that influence affinity of Hb for oxygen
pH - Low PH the less saturation as acidity increases unloading
Partial pressure of CO2 - As it rises O2 is released more readily as more carbonic acid so more H+. More acidity means less affinity
Temperature - Heat produces more acids
BPG - produced from break down of glucose. Decreases affinity
Bohr effect
PH decreases
Curve shifts to right
Increase in H+ - more acidity - more unloading
Contrastingly increases affinity increases and curve shifts to left
Normal range valves for arterial blood gases
pH: 7.35-7.45
pO2: 10-14kPa
pCO2: 4.5-6kPa
Base excess: -2-2mmol/l
HCO3: 22 - 26mmol/l
Respiratory control
Sensors (chemoreceptors and mechanoreceptors)
Respiratory control centre (medulla and pons)
Effectors (respiratory muscles and diaphragm)
Chemoreceptor
Responds to chemical compounds
Oxygen receptors - peripheral NS
Carbon dioxide - peripherally and centrally
Stretch receptor
Respond to stretch of muscles sending impulses to CNS
Where is the medulla and pons
Part of the brain stem
pneumotaxic centre
Upper aspect of the pons
Controls fine tuning of respiratory rate and depth
Sends signals to influence the VRG and DRG
Apneustic centre
Lower aspect of the pons
Controls prolonged breathing
Sneds signals to VRG and DRG to trigger inspiration
Dorsal respiratory group
DRG
Medially in aspect within the medulla
Receives peripheral stimulus from stretch receptors, proprioceptors and juxtacapillary receptors
Sends signals to external intercostals and diaphragm for inspiration
Ventral respiratory group
VRG
Anterior aspect of medulla
Controls expiration via sending expiratory signals
Central chemoreceptors
when inactivated respiration ceases
Located in brainstem on ventrolateral surface of the medulla
Respond to hydrogen ion concentration and low partial pressure of oxygen
when carbonic acid increases Chemoreceptors promote increased ventilation
Peripheral chemoreceptors
Located in cartoid sinus and aortic arch
sensitive to
PaO2
PaCO2
pH
Blood flow
Temperature
Factors affecting rate and depth of breathing
Increase:
Voluntary hyperventilation
Increase in PCO2 above 40mmHg
Decrease in PO2 from 105mmHg to 50mmHg
Increased proprioreceptor activity
Increase in body temperature
Prolonged pain
Decrease in blood pressure
Stretching of anal sphincter
Decrease
Voluntary hypoventilation
decrease in PCO2 below
Decrease in PO2 below 50mmHg
Decrease Proprioreceptor activity
Decrease body temperature
Severe pain
Increase in blood pressure
Irritation of pharynx or larynx
Normal ranges for body components
Temperature 37 degrees c
Heart rate 60-99 per minute
Blood pressure 120/80 mmHg
Respiratory rate 12-16 breaths per minute
Oxygen saturation 95%-100%
pH 7.3-7.5
what is auscultation
Technique to listen to internal sounds of the body
Heart:
Aortic area
Pulmonic Area
ERB’s point
Tricuspid area
Mitral area
Lung
Check bronchial, bronchovesicular, vesicular
Abnormal sounds
Bronchial - loud, high pitched
Bronchovesicular - medium pitched
Vesicular - soft, low pitched sounds
Diminished lung sounds, adventitious breath sounds
