P L1 Flashcards
differences in what allows for the exchange of gases
Differences in partial pressure of O2 and CO2
What is external and internal resp? whr does it occur? what are the Partial P’s differences in each? how does it vary?
External –> occurs in the alveoli
Gas exchange occurs btwn the alveoli and pulm blood caps.
Higher O2 Partial P (PP) in the alveoli and lower CO2 PP in the alveoli compared to surrounding pulm caps.
Thus O2 diffuses out of alveoli into caps and CO2 diffuses out of caps into alveoli
Internal –> Occurs within cells and between cells and surrounding blood capillaries through the interstitial fluid surrounding the cells and caps.
Also occurs due to PP differences
PP differences here are opp to those in the alveoli
There’s a higher PP of O2 in the blood and lower PP of CO2. While the cells have a higher PP of CO2 and a lower PP of O2.
Thus O2 diffuses into the cells from the blood caps and CO2 diffuses out of the cells into the surrounding blood caps
What are the regulated variables that play a role in homeostasis?
- O2
- CO2
- pH
How are variables (O2, CO2 and pH) in homeostasis controlled?
They are often controlled by negative feedback loops
** (IMP) Controlling the rate and depth of breathing controls the levels of O2, CO2 and pH within tightly controlled limits
Describe some pathways that are a part of the respiratory control system
1) Most imp. one –> Resp center in the brainstem sends APs to elicit muscle contraction –> Causes an increase in the rate and depth of breathing –> Increases lung volume –> Signals lung stretch receptors –> -ve feedback: sends signals to resp center in brainstem for relaxation
2) Other sensory afferents:
They continuously sample blood/cerebrospinal fluid to check for levels of O2, CO2, pH etc.
3) Higher Brain centers:
Control through conscious control of breathing like during talking, eating (stop breathing when swallowing), stress (hyperventilate), pain, laughter, sleep/wake cycle (breathing slows down)
4) Chemoreceptors:
Increased CO2 or decreased O2 signals chemoreceptors to increase breathing
What system is the resp system usually coupled with?
Cardiovascular system
What are the 3 stages of respiration? Which nerves are active during them?
- inspiratory :: Phrenic and hypoglossal and intercostals
- Post inspiratory :: vagal nerves
- expiratory :: none (passive)
What are the respiratory muscles?
Inspiratory muscles:
– Diaphragm
– External intercostal musc (pulls chest wall up to inc lung vol.)
Inspiratory auxiliary muscles:
– Parasternal intercostals
Expiratory muscles (expiration is passive however, these muscles are used in forced expiration):
– Abdominal
– Internal intercostal
What are the inspiratory muscles? Which intercostal musc used?
Diaphragm
External intercostal musc.
What are the inspiratory auxillary muscles? Which intercostal musc used?
There are multiple inspiratory auxiliary muscles:
–> Parasternal intercostal muscles
- Genioglossus
- Geniohyoid
- Sternohyoid
- Scalene
- Sternocleidomastoids
What type of processes are expiration and inspiration generally?
Inspiration – active process – requires use of muscles
Expiration – usually passive process – involves relaxation of inspiratory musc to exhale the air
– but active expiration can also occur thru recruiting the expiratory muscles.
What are the expiratory muscles? Which intercostal musc used?
Abdominal muscles
Internal intercostal
How is muscle activity measured? What condition can it be important in detecting?
Using electromyography
Used to measure electrical activity within the musc
Used to measure activity of muscles during inspiration and expiration
Can be used to detect the condition called ALS (Amyotrophic Lateral Sclerosis)
– Its a progressive nerve disease and affects the brain and SC
– Disease where there’s loss of musc control due a decrease in the recruitment of musc by nerve cells
Which is the principle inspiratory muscle and what center in brain excites it? Which direction does it move in during inspiration?
The diaphragm
The central resp. patter generator
During inspiration the diaphragm contracts and moves downwards – causing an increase in the thoracic cavity
_______ is closely related to function
structure
Define how structure and function are related
Structure –> Structure is the way each component in inter-related
Function –> Function is the operation of each individual component as part of the structure
_____ is the way each component in inter-related
Structure
_____ is the operation of each individual component as part of the structure
Function
What are the types of tissue? Where are they found? What is their function? Give examples
Epithelium
– Line body surfaces and provide protection
– squamous, cuboidal, columnar (simple/stratified)
Connective tissue
– They provide tensile strength and elasticity
– EX: collagen (most abundant protein in body) and elastin (elastic recoil + stretching)
Muscle
– motile force thru contraction
– Skeletal musc, smooth muscle
Nervous tissue
– Receive stimuli from external and internal envrmts and analyse and integrate signals
What are the functions of the airways
PRIMARY::
It’s primary function is to match ventilation with perfusion and it does so by conducting gas thru the airways and allowing for gas exchange
–> Conducting Zone: Area which conducts air in and out of the site of gaseous exchange (Site associated with Mechanical respiration only - not cellular )
–> Respiratory Zone: The extensive area for gaseous exchange – provides O2 and removes CO2 and thus maintains blood pH levels
Thus its function is to match ventilation (air flow) with perfusion (blood flow)
SECONDARY:
- To maintain patency
- To humidify and warm air
- to clean particulates/fight infections (have prostaglandins and histamine (in all airways))
- Produce sounds
- site for olfactory sensation
Which primary function/zone of the lung is associated with mechanical respiration only
The conducting zone
What is the respiratory zone
What structures does it include?
Its the extensive site for the exchange of gases
Provides O2 and removes CO2
Maintains blood pH
Structures:
– Respiratory bronchioles
– Alveolar ducts
– Alveolar sacs
What is the conducting zone
It is involved in only mechanical resp.
It involves the movement of air in and out of the site of gas exchange
Structures:
– Trachea
– Bronchi [ Primary bronchus, Secondary bronchus (lobar), Tertiary bronchus (segmental)]
– Bronchioles
What are the main subdivisions of the respiratory tract?
UPPER RESP TRACT:
- Nose
- Pharynx
- Larynx
LOWER RESP TRACT:
- Trachea
- Bronchi
- Bronchioles
- Lungs
- Alveoli
What are the features of Respiratory mucosa? What type of epithelial cells does it have? What part of the nasal cavity does is not lined by resp. epithelium?
It forms the mucosal lining of the nasal cavity
- It is made of stratified columnar epithelial cells
- It has goblet cells
- It has mucus glands
- It has a rich blood supply to warm the air
The nasal cavity contains 2 types of mucosa:: Respiratory and olfactory mucosa.
The part of the nasal cavity near the roof is lined by the olfactory epithelium instead and contains olfactory receptors
[The transduction of olfactory information occurs in the olfactory epithelium, the sheet of neurons and supporting cells that lines approximately half of the nasal cavities. (The remaining surface is lined by respiratory epithelium, which lacks neurons and serves primarily as a protective surface.)]
What are the 2 types of mucosal linings found in the nasal cavity? What part of the nasal cavity are they found in?
Consists of Respiratory and olfactory mucosa.
Respiratory mucosa::
– Lines the entire nasal cavity with the exception of the roof
Olfactory mucosa::
Found near the roof of the cavity
Houses smell receptors
What is the function of Bowmans/ Olfactory glands?
- They release secretions thru ducts onto the epithelium lining the nasal cavity
- Secretion produces a fluid envrmt arnd the cilia
- This allows the cilia to clear the contaminated mucus posteriorly to allow access of new odoriferous substances
** Also produce a number of olfactory binding proteins
What receptors contribute to the diving reflex?
Receptors for cold and touch located in the face and nose
What is the diving reflex? What nerves are involved in the initial stimuli? What organ system is involved in the initial and secondary stimuli? What is the secondary stimuli?
What part of the brain do the signals get sent to?
INITIAL RESPONSE:
– Cold or wetness detected in the face by receptors
– Stimuli passes thru trigeminal nerve (main) and also glossopharyngeal n.
– Signals Respiratory center in medulla oblongata
– Which then signals resp. muscles
– Causes apnea (a stop in breathing)
– Prevents from breathing in water
SECONDARY RESPONSE
– A decrease in O2 conc. detected by arterial chemoreceptors
– Signals CVS center in medulla oblongata
– Causes a sympathetic and parasympathetic response
–> sympathetic: Vasoconstriction of peripheral BVs to direct blood to brain and heart
–> parasympathetic: Bradycardia to reduce energy consumption of heart
What cells line the nasopharynx and the oropharynx?
Nasopharynx:
- Pseudostratified ciliated columnar epithelium +goblet cells
Oropharynx:
- Stratified squamous epithelium (as its subject to abrasion)
why is snoring caused
Due to a partial obstruction of the airway
Which part of the respiratory tract is the most vulnerable to collapse in apnea?
The oropharynx
What is obstructive sleep apnea?
Apnea - a pause in breathing
- Requires arousal to reestablish airflow
- larynx particularly vulnerable due to lack of support to maintain its patency
- when we sleep - relaxation of our musc+body posture can lead to collapse of larynx
- often in obese ppl
How many lobes do the right and left lungs have?
Right - 3 lung lobes
Left - 2 lung lobes
What lines the outside of the lungs?
The visceral pleura
What forms the boundaries of the pleural cavity?
The visceral pleura and the parietal pleura
What is the blood supply of both the pleura lining the lungs?
Visceral pleura - Bronchial circ.
Parietal pleura - Intercostal arteries
What is pleuritis/pleurisy? Why is the diseased area vulnerable to this?
It is an infection of the pleural cavity by bacteria or other microorganisms
Vulnerable as it doesnt have any immune cells?
What is tidal volume?
A normal person, when breathing quietly without any active effort, takes in about 500 ml or half a liter of air - this is the tidal volume
Almost a third of this tidal volume or about 150 ml is trapped in this anatomic dead space, and the remaining 350 mL or so is used for gas exchange.
Anatomical and physiological dead space
Anatomical dead space:
– It is the air that we inhale that does not take part in gas exchange and is situated in the conducting zone
– Air in the nose, mouth, trachea, bronchi and bronchioles. (conducting zone)
– Cannot be altered (no matter what we do we cant use this air for gas exchange) - always remains at 150 ml/breath as it’s built in to the anatomy of the body
Physiological dead space:
– Vol of air in each breath that’s not involved in gas exchange
– Sometimes the alveoli are well ventilated but not well perfused (narrow blood caps) this leads to less gas exchange and more dead space air
– This value thus includes the unventilated and poorly perfused alveoli + anatomical dead space
– In a healthy individual this value is close to 150 ml/breath
– This value increases greatly in disease (due to inc. in unventilated/poorly perfused alveoli)
How many branches do the airways divide into each time? what is this type of division of airways called? What does this allow for?
They divide into 2 each time
Dichotomous airways
Large surface area at alveolar level
Large area for gas exchange
What type of cartilage are the c-shaped cartilage? are they flexible? What is their function?
They are hyaline cartilages
They provide flexible support
They maintain the patency of the trachea (hold the airway open)