Slide Set 6 - Respiration Flashcards
How does the respiratory centre know when to breath?
Through sensory input
What sensory input does the brain receive which allows it to know when to breath?
The pneumotaxic centre and apneustic centre of the pons (section of our brain involved in the control of breathing and communication between different parts of the brain) receive signals from the chemo and barre receptors. Once the pons receive these signals, it relays them to the medullary rhythmic area which relay information to the respiratory muscles that drive breathing
So basically: Chemo&Barro-receptors send signal to pons –> medullary rhythmic area –> respiratory muscles
What part of our brain can “override the “automatic” control of breathing?
cerebral cortex
What two areas is the medullary rhythmic area made up of?
- Inspiratory area
2. Expiratory area
What are the 4 respiratory functions?
- external respiration
- transport of gases by the blood
- internal respiration
- regulation of respiration
What are the 2 divisions of the respiratory system?
- Upper respiratory tract
- Lower respiratory tract
+ accessory structures
What makes up the upper respiratory tract?
Nasal cavity, tongue, larynx, esophagus, pharynx
What makes up the lower respiratory tract?
Trachea, right lung + right bronchus, left lung + left bronchus
What are the 2 muscles of inspiration?
- external intercostals
2. diaphragm
What are the 3 muscles of expiration?
- internal intercostals
2. abdominal muscles
What are two secondary muscles used in inspiration and expiration?
Sternocleidomastoids & Scalenes
What path does the air we inhale take from the moment we inhale to the moment it reaches the blood?
Down trachea to the bronchi where bronchioles branch off and become smaller and smaller until then end in alveolar sacs. Alveolar sacs exchange the incoming air with the RBCs in the capillaries that surround the sacs
In what fashion do the RBCs travel through the capillaries that surround the alveolar sacs? What is the structure of the endothelial cells within these capillaries?
Single file line: for max O2/CO2 exchange
single layered
What is the function of the pulmonary arterioles?
bring deoxygenated blood from the heart to the lungs in order to be oxygenated by the capillary network on alveolar sacs
What is the function of the pulmonary vein?
Returns oxygenated blood from the capillary network on the alveolar sacs back to the heart to be pumped out the rest of the body
What are the functions of the alveolar sacs?
- allow exchange of O2 and CO2 with blood
- filter air via macrophages (large non-discriminant cells of immune system)
What is cleft palate?
Failure of the nose and the mouth to unite (partial separation) – due to malformation of palatine bone caused by decreased migration of neural crest cells
What are causes of cleft palate?
- genetic mutation of trisomy on chromosome 13
- environmental - consumption of the teratogenic drugs by mother during pregnancy: corticosteroids, benzodiazepines, anticonvulsants
How can cleft palate be fixed after birth?
Plastic surgery: if there is a gaping the gum, bone graft may be used to fill it
What can a mother do in order to decrease the levels of her baby obtaining cleft palate? Causes ___ reduction
Taking multivitamin with folic acid. Causes 48% reduction
What component of the nose serves as a filter to screen particles from the air?
hairs that line the nose
What component of the nose functions to moisten the air as it passes by?
The turbinates which provide a large mucus-covered surface
What is an important function of mucus in the nose?
traps particles before air enters respiratory system
What does the pharynx connect?
The upper and lower airways
Pharynx = throat
What is the structure of the pharynx?
tubelike structure extending from the base of the skull to the esophagus - made of muscle
What 3 parts is the pharynx divided into?
Nasopharynx, oropharynx, and laryngo-pharynx
The pharynx is a pathway for what 2 systems?
- Respiratory system
2. digestive system
What happens in the pharynx upon swallowing food?
Swallow reflexes close the trachea allowing the food to go down the esophagus and into the stomach.
How does the pharynx produce certain vowel sounds?
by changing shape
Where are the lower respiratory tract organs located and what organs are they?
Located within the thorax
Organs:
- trachea
- bronchial tree
- lungs
What are the 3 accessory structures of the respiratory tracts?
- Oral cavity
- rib cage
- diaphragm
What parts of the upper and lower respiratory tracts does the trachea connect?
Larynx to the bronchi
What does obstruction of the trachea lead to?
death
What type of muscle is the trachea made of and what is embedded in it?
Smooth muscle which are embedded with cartilage C rings
Ciliated epithelium of the trachea - what is the role of:
- Goblet cells?
- Cilia?
- Mucus layer?
- Watery saline layer between the cilia and mucus later?
- secrete mucus
- push mucus towards pharynx
- traps inhaled particles
- allows/helps cilia push mucus forward
What are the 3 layers of bronchial walls?
- epithelial
- smooth muscle
- connective tissue
What form alveolar sacs?
Bronchioles subdivide to form tiny tubes called alveolar ducts, which end in clusters of alveoli called alveolar sacs
What are the pores of Kohn?
channels running between two adjacent alveoli across the alveolar wall
What forms the alveolar wall?
a single layer of type 1 alveolar cells
Alveolar sac: what is the respiratory membrane?
the barrier between which gasses are exchanged by alveolar air and blood
What is the respiratory membrane barrier made up of?
- alveolar epithelium
- capillary epithelium
- joined basement membranes
What is the surface of the respiratory membrane inside each alveolus coated with? What is the function of this coating?
Coated with surfactant which reduces surface tension produced by type 2 cells
What is inspiration?
the process of taking air into the lungs.
Why is inspiration considered the active phase of ventilation?
because it is the result of muscle contraction
During inspiration, what happens to the:
- Diaphram?
- Thoracic cavity?
- Intra-alveolar pressure?
- Lungs?
- contracts and moves downwards
- increases in volume
- decreases
- air flows in
What is expiration?
exhalation - the process of letting air out of the lungs
During expiration, what happens to the:
- Diaphram?
- Thoracic cavity?
- Intra-alveolar pressure?
- Lungs?
- Relaxation
- decreases in volume due to elastic recoil of tissue
- increases
- air flows out
What two gas pressure gradients must pulmonary ventilation establish?
- one in which the pressure within alveoli of lungs is lower than atmospheric pressure to produce inspiration
- on in which the pressure in alveoli of lungs is higher than atmospheric pressure to produce expiration
How are pressure gradients established during pulmonary ventilation?
by changes in size of thoracic cavity that are produced by contraction and relaxation of muscles
What are the 3 steps of the respiratory cycle?
- During inspiration the diaphragm contracts, increasing the volume of the thoracic cavity
- This increases in volume results in a decrease in pressure, which causes air to rush into the lungs
- During expiration, the diaphragm returns to an upward position, reducing the volume in the thoracic cavity. Air pressure thus increases, forcing air out of the lungs
What is the atmospheric pressure (PB) that occurs during ventilation?
the air pressure of the atmosphere outside of the body’s airways
What is alveolar pressure (PA) that occurs during ventilation?
intrapulmonary pressure - the pressure at the far end of the internal airways
What is intrapleural pressure (PIP) that occurs during ventilation?
It is the fluid pressure of the pleural fluid between the parietal pleura (outer membrane attached to the chest wall) and visceral pleura (membrane surrounding the lung). This pressure is created by the 2 membranes that surround the lungs
What is the primary principle of ventilation?
air moves down its pressure gradient - always moves from an area of high pressure to an area of lower pressure
Where must the higher pressure be in order to achieve inspiration?
outside the body
Where must the higher pressure be in order to achieve expiration?
inside the body
Expansion of the thorax and downward movement of the diaphragm results in ______ intrapleural pressure (PIP), leading to _______ alveolar pressure (PalV)
decreased, decreased
Air moves into lungs when _______ pressure drops below _______ pressure.
alveolar, atmospheric
What is compliance?
The ability of pulmonary tissues to stretch, making inspiration possible
What is surfactant? what produces it? what is its function?
A lipoprotein that is formed from protein and phospholipid secretions by type 2 cells in the wall of the alveolus.
Function: reduces surface tension and prevents alveolar collapse during exhalation
How do surfactants prevent the lungs from collapsing during expiration?
They are interspersed between water molecules which decreases the attraction of water molecules to one another - promoting expansion of the lungs and acting agains the tendency to recoil. If surfactants didn’t prevent water molecules from being attracted to one another, the size of the alveolus would decrease
What are the primary phagocytes of the innate immune system? Function? What do they secrete?
Alveolar macrophages
Function: clear the airspaces of infectious, allergic, or toxic particles. Are capable of eliminating the small inocula of typical microbes which are aspirated daily in the normal host.
Secrete lysozymes, antimicrobial peptides and proteases via phagocytosis
What 3 factors determine the amount of oxygen that diffuses from the alveolar air into the blood?
- total functional surface area of the respiratory membrane
- the respiratory volume
- alveolar ventilation
What are 4 structural factors that facilitate oxygen diffusion from alveolar air to blood?
- capillary bed
- walls of the alveoli and capillaries from only a very thin barrier of gasses to cross
- alveolar and capillary surfaces are large
- blood is distributed through the capillaries in a thin layer so each RBC comes close to alveolar
What is the negative feedback control of respiration?
The feedback loop that operates to increase the respiratory rate in response to high plasma CO2
What are the 3 main stages of the negative feedback control of respiration?
- increased cellular respiration during exercise causes a rise in plasma plasma CO2, which is detected by central chemoreceptors in the brain and perhaps peripheral chemoreceptors in the carotid sinus and aorta
- Feedback information is relayed to integrators in the brainstem that respond to the increase in plasma CO2 above the set point value by sending nervous correction signals to the respiratory muscles, which act as effectors
- The effector muscles increase their alternate contraction and relaxation, thus increasing the rate of respiration. As the respiration rate increases, the rate of CO2 loss from the body increases and plasma CO2 drops accordingly. This brings plasma CO2 back it its normal set point
Changes in what 3 components of arteriole blood influence the medullary rhythmic area?
- plasma O2
- plasma CO2
- pH
Which chemoreceptors does a change in plasma CO2 affect? How does it affect it?
central chemoreceptors in medulla
If plasma CO2 increases –> faster breathing
If plasma CO2 decreases –> slower breathing
Which chemoreceptors does a change in plasma pH stimulate?
peripheral chemoreceptors in the carotid and aortic bodies + the central chemoreceptors
Which chemoreceptors does a change in plasma O2 affect?
barely any effect as long as it stays above certain level
How does the cerebral cortex influence breathing?
by increasing or decreasing rate and strength of respiration
What happens to air tubes during chronic bronchitis? What is this a result of?
They narrow as a result of swollen tissues and excessive mucus production
What is asthma?
Edema of respiratory mucosa and excessive mucus production - obstructs airways
What is emphysema?
Enlargement and destruction of alveolar walls - walls of alveoli are torn and cannot be repaired - alveoli fuse into large airspaces
