Respiratory Flashcards
Regions of the pharynx?
Pharynx = throat
1. Nasopharynx (nostrils to soft palate)
2. Oropharynx (soft palate to hyoid bone)
3. Laryngopharynx (hyoid bone to cricoid cartilage/oesophagus)
Impact of vocal cord movement on speech?
Cords adducted = high pitched sound
Cords abducted = lower pitch sounds
Difference between conducting zone and gas exchange zone of the lungs?
Conducting zone - terminal bronchioles, high resistance to airflow
Gas exchange zone - respiratory bronchioles/alveoli, very low resistance to airflow, pleural pressure more negative at apex (with bigger gradient in taller people)
Levels of the bronchial tree
Trachea -> primary bronchi -> secondary (lobar) bronchi -> tertiary (segmental) bronchi -> bronchioles -> terminal bronchioles -> respiratory bronchioles -> alveolar ducts -> alveolar sacs
What are the bronchopulmonary segments?
Each portion of lung supplied by each tertiary bronchus is called the bronco pulmonary segment
Overview of bronchioles
Continuations of airways that lack supportive cartilage
Each portion of lung ventilated by one bronchiole is a pulmonary lobule
Walls made of well-developed smooth muscle (ciliated cuboidal epithelium)
Anatomy of terminal bronchioles
50-80 branch from bronchioles
No mucous glands or goblet cells, but retain cilia
Last area of the CONDUCTING zone (conducts air)
Anatomy of respiratory bronchioles
First part of the RESPIRATORY zone
Narrowed airways of the lungs
Alveoli bud from walls
Not much smooth muscle or cilia
Anatomy oc alveolar ducts
2-10 from each respiratory bronchiole
Alveoli along walls
No cilia
Overview of alveoli
150million in the lungs
70m2 surface area for gas exchange
Types of cells include type 1, type 2 and alveolar macrophages
Type 1 alveoli
95% surface area
Squamous cells
Function for rapid gas exchange
Type 2 alveoli
5% surface area
Cuboidal and much more numerous than type 1 (although less surface area)
Function to repair alveolar epithelium and secrete surfactant
Surfactant = protein and phospholipid solution that coats alveoli and prevents collapse during exhalation due to reducing surface tension
Alveolar macrophages
Most numerous cells in the lung
In alveoli and surrounding connective tissue
Function to remove foreign matter and bacteria via phagocytosis
Respiratory membrane
= barrier between alveolar air and blood
Made up of squamous alveolar cells (type 1), basement membrane (shared) and squamous endothelial cell of capillary (pulmonary arterial supply)
Total thickness of 0.5micrometres
Pulmonary circulation MAP 10mmHg (allows gas exchange and keeps alveoli dry)
Oncotic pressure 25mmHg in alveolar capillaries, therefore keeps alveoli dry
Parietal pleura
Reflection of visceral pleura on the inner surface of the chest wall, mediastinum, diaphragm
Visceral pleura
Serous membrane covering the surface of lung to hilum
Pleural space
Refers to space between parietal and visceral pleura
Contains pleural fluid, is a potential space
Functions to reduce friction, create pressure gradient for ventilation, compartmentalisation to reduce spread of infection
What type of embryonal tissue does the respiratory system develop from?
Endoderm
Embryonic stage of lung development
Week 4-5 (other resource says week 3)
Lung buds originate from the primitive foregut
Pseudoglandular stage of lung development
Approx week 5-16
Airway branching begins, lobar structure apparent
By the end of this phase, all the conducting airways have been fully developed, and the vascular development is complete
Canalicular stage of lung development
Approx week 16-25
Bronchioles are produced, increasing number of capillaries
Type 1 and II alveolar cells form
Air-blood barrier forms
Saccular stage of lung development
Approx week 24-36 weeks
Alveolar ducts and air sacs are developed
Vascular expansion occurs
True alveoli seen by 32 weeks, recognisable by 36 weeks
Alveolar stage of lung development
Occurs from late gestation (32 weeks onwards) to childhood
Marked increase in the number and size of capillaries and alveoli
Most development is postnatal (85% of alveolarization occurs postnatally)
15 million alveoli at birth (term baby) -> 300-600 million as an adult (exponential increase until 2 years old)
Overview of lung development postnatally
Birth to 3 years: formation of true alveoli, further complexity of gas-exchange airways
3-8 years: increase size and complexity of alveoli, pores of Kohn (collateral ventilation)
Surfactant development and production
Type II alveolar cells present from 20-24 weeks
Surfactant secretion from 30 weeks
Neurological regulation of respiration
Central control centre = 2 groups of neurons
1. Brainstem (pons and medulla) = pre Botzinger complex
2. Cortex (voluntary control)
Brainstem regulation of respiration
Neurons in medulla and pons control inspiration (dorsal respiratory centre) and expiration (ventral respiratory group)
Pneumotaxic centre controls rate and pattern of breathing, limits inspiration
Inputs from peripheral sensors, can be overridden by cortex
Automatic rhythmic inspiratory stimuli and sometimes expiratory
Major output is to the phrenic nerves
Cortex regulation of respiration
Cerebral motor cortex and limbic structure, voluntary control
Receives sensory input from respiratory muscles via corticobulbar and corticospinal tracts
Respiration sensors
- Central chemoreceptors
- Peripheral chemoreceptors
- Lung and other receptors (pulmonary stretch, irritant receptors, J receptors, muscle receptors, arteriolar baroreceptors and pain/temperature receptors)
Overview of central chemoreceptors and regulation of respiration
Situated on ventral surface of medulla, surrounded by CSF
Respond to CSF [H+]
CSF [H+] is a reflection of CO2 in cerebral capillaries
Increased PaCO2 leads to increased CSF [H+], leads to increased ventilation
Does not respond to PaO2