L36 - Respiratory System Anatomy Flashcards
What are the different sections of the respiratory system?
- upper respiratory system
- lower respiratory system
What are the parts of the upper respiratory system?
- nasal cavity
- pharynx
- larynx
What is the upper respiratory in charge of?
- humidify and warm air
- defence - mucus and cilia
- sensory
- speech
What are the parts of the lower respiratory system?
- trachea
- primary bronchi
- …
- lungs
What is the lower respiratory system in charge of?
- gas exchange
- defence
- metabolic
What is the lower respiratory tract like?
- trachea - circular cartilage, give structure and support
- terminal bronchiles - without cartilage
- bronchi and bronchioles - surrounded by smooth muscle
What is the airway beyond larynx divided into?
- conducting zone (no alveoli, no gas exchange)
- respiratory zone (have alveoli)
What are the functions of the conducting zone?
- pathway for airflow
- defence against pathogens and particulates
- warm and moistens air
What is the respiratory zone like?
- Number of alveoli inc in alveolar ducts
- airways end in grape like clusters - alveolar sacs
What is the function of respiratory zone?
Gas exchange
What is airway resistance?
Resistance to the flow of air through the respiraoty tract during inhalation and expiration
What is airway resistance like?
- strongly affected by diameter of airway
- trachea through bronchus radius decreases, resistance increases
- single = more resistance
- large to medium size = more resistance to flow
- conducting zone bronchioles = largest resistance
What is the eqn to calculate airways resistance?
Airways resistance = 1/conduction
What are intermittent episodes of asthma?
Airway smooth muscle contracts = increasing airway resistance
What is chonic inflammation like in asthma?
- smooth muscle hyperresponsive = strong contraction
- allergy, viral infection, exercise in cold dry air, tobacco smoke, env pollutants
What is medication for asthma?
- anti-inflammatory = reduces chronic inflammation
- bronchodilators = relax airway
- act on large and medium airways = increase radius
What does an increased airway resistance cause?
- diseases. =chronic inflammation = thickening of airway walls
- reduces airflow, prevents mucus drainage
- more mucus = inc chances of infection, scarring, loose elasticity and thickening of walls
- = collapse of airways if walls stick together
What is the lung epithelium?
- lining cells in airway
- specialisation changes down the airway
What are the specialiastion of the lung epithelium?
- bronchi - ciliated, goblet, glandular
- bronchioles - ciliated, non-ciliated, goblet, club cells
- alveoli - squamous, cuboidal
What are mucous-producing goblet cells?
- 2 layers - sol layer and gel layer
- gel layer - produed by the goblet cells
- gel layer - contains chemicals, a/bod, immune cells destroy any bacteria viruses
- gel layer - assists with the trapping and removal of inhaled foreign particles
What is immunity like in the respiratory system?
- oral and nasal cavities - trap airborne partciles in hair and mucus
- epithelial surfaces - contain cilia, club cells, goblet cells and glands
- smoking dec num of cilia and activity = sticky mucus
- cf - dehydrated, sticky mucus due to mutation in CTFR gene = mucus obstructions bacteria populate in
What do the epithelial cells have and their functions in immunity?
- cilia - beat particles upwards
- club cells - secrete // surfactant proteins
- goblet cells and glands - secrete mucus
- phagocytes in tissue
What is the respiratory unit?
- network of airways and air sacs (500 mil) = maximise SA (50-100m^2)
- SA of alveoli 80m^2
What is parenchyma?
- functional unit
- Respiraroty Bronchiole (RB)
- Alveolar Duct (AD)
- Alveoli
What is type I of alveolar epithelial cells (pneumocytes)?
- large SA (95% alveolus, 10% cells)
- squamous
- gas exchange
What is type II of alveolar epithelial cells (pneumocytes)?
- cuboidal (majority of cells) and granular
- secretory (surfactant)
- precursors for type I
What are surfactants produced by?
type II alveolar epithelial cells (lipid, proteins - SP-A, -B, -C, -D
What do surfactants do?
- reduces surface tension (prevents alveolar collapse)
- innate immunity function
- instilled into babies with infant respiratory distress syndrome (beractant - bovine, pumactant - synthetic lipid)
What are lungs like at birth?
- lung epithelium develop in last trimester of pregnancy
- lung is fluid filled in foetus
- C-section reduced drive for fuild absorption
What is maturation of lung epithelium stimulated by?
Corticosteroids in premature babies
How do fluid filled lungs in foetus rapidly empty?
- surge in corticosteroids and catecholamins at birth
- activation of absorptive channels // Epithelial sodium ENaC
- pressure changes (squeeze through birth canal)
What are the 2 circulatory systems that supply blood to the lungs?
- pulmonary circulation
- bronchial circulation
What is the pulmonary circulation like?
- artery flows directly from right ventricle
- low O2, high flow, low pressure
- capillaries around the alveoli
- pulmonary vein returns oxigenated bloos to left heart
What is the bronchial circulation like?
- from aorta (left ventrivle)
- high pressure
- supplies oxygen and nutrients the conducting airways
- not involved in systemic respiration processes
- 2%of cardiac outflow
What is ventilation?
- movement of air from environment into the lungs (breathing)
- automatic and CNS controlled
What is neuronal control of breathing?
Smooth muscles and glands of respiratory system are controlled by parasympathetic division of ANS
What are the respiratory muscles?
- inspiratory - external intercostals, diaphragm
- expiratory - internal intercostals, abdominal muscles, diaphragm
What are the 3 types of muscle innervation?
- somatic motors nerves
- autonomic nerves
- sensory output
What are the somatic motor nerves like?
- innervate skeletal muscles in thorax
- phrenic - innervate diaphragm, irritation = hiccough
- intercostal
What are the autonomic nerves like?
- bronchial
- supply smooth muscle and secretory cells
- branch from vagus
- reflex bronchospasm and mucus secretion
- important in asthma
What is smooth muscle innervation like in terms of neurotransmitters?
- Ach - excitatory/contraction
- NO - inhibitory/relaxation
What is gland innervation like in terms of neurotransmitters?
- Ach
- little sympathetic innervation
- b2-adrenoceptors on airway smooth muscle, stimulated by circulating adrenaline causing bronchodilation
Neurotransmitters and receptors in the ANS
Inhalation therapy for pulmonary diseases
What is the sensory afferent pathways from the lung like?
- send impulses via vagus to medullary centres
- slowly adapting stretch receptors (SAR)
- rapidly adapting stretch receptors (RAR)
What are SARs like?
- stimulated by stretch receptors in airway smooth muscle
- elicit reflexes
- shortened inspiration
- hering breuer reflex (promotion of expiration following steady inflation, prevents overinflation of lung)
What are RARs like?
- stimulated by sudden, sustained inflation
- by irritant receptors in epithelium
- elicit reflexes (cough, bronchoconstriction, mucus secretion)
What are pleural membranes like?
- double membrane surrounding the lungs
- left and right pleura anatomically distinct
- very small amound of pleural fluid between membranes (serous fluid)
- lubricant
What happens in ventilation?
- fluid in pleural sac helps lung wall stick to inside of thorax
- contraction of diaphragm and external intercostal muscles
- exhalation passive at rest (elastic recoil)
What happens during contraction of the diaphragm and the external intercostal muscles?
- increased lung volume
- internal pressure falls (boyles law)
- air drawn into lungs
What are the metabolic functions of the lung?
- vascular cells activate angiotensin I
- inactivate some circulating hormones
- fibrinolytic function
- club cells detoxify inhaled substances
What do vascular cells do to agiotensin I?
- ang i converted to pressor ang ii
- angiotensing converting enzyme (ACE)
- bradykinin (vasoactive)
- serotonin
What circulating hormones do vascular cells inactivate?
- protaglandins E1, E2 and F2alpha
- norepinephrine
