respi - phyanalec Flashcards
- Ventilation /Breathing – movement of air into and out of the lungs
- Exchange of O2 and CO2 in lungs and blood
- Transport of O2 and CO2 in blood
- Exchange of O2 and CO2 between blood and tissues
4 processes of respiration
-process of moving air into and out of the lungs
VENTILATION OR BREATHING
Two Phases VENTILATION OR BREATHING
- Inspiration- movement of air into the lungs, inhalation
2. Expiration – movement of air out of the lungs, exhalation
Muscles of Inspiration)
– diaphragm & muscles that innervate ribs and sternum (external intercostals
– large dome of skeletal muscles that separates the thoracic cavity from abdominal cavity
• Diaphragm
depress ribs and sternum (ex. Internal intercostals)
Muscles of Expiration –
type of breathing
– all inspiratory muscles are active
-muscles contract more forcefully → greater increase in thoracic volume → faster and greater decrease in thoracic volume
labored
Principles governing Airflow
- ↑Pressure, ↑Volume
- Air flows from an area of higher pressure to an area of lower pressure
Greater the pressure difference, greater rate of airflow
phase
– alveolar pressure = atmospheric pressure
end of expi
phase
– contraction of muscles of inspiration, ↑thoracic volume, ↑lung expansion, ↑alveolar volume, AVP < ATP, air enters alveoli
during inspi
phase
– thorax and alveoli stop expanding
- AVP = ATP, airflow stops
end of inspi
phase
↓ thoracic volume, ↓ alveolar volume, AVP > ATP, air leaves alveoli
- During Expiration -
-tendency for an expanded lung to decrease in size
LUNG RECOIL
causes of LUNG RECOIL
elastic tissue
surface tension
– exists because oppositely charged ends of water molecules are attracted to each other
-as water molecules pull together, they pull on alveolar walls, causing alveoli to recoil and become smaller
surface tension
FACTORS THAT KEEP THE LUNGS FROM COLLAPSING
surfactant pleural pressure
mixture of lipoprotein molecules produced by secretory cells of alveolar epithelium
-its molecules form a single layer on the surface of the thin fluid layer lining the alveoli, reducing surface tension
- Surfactant –
– pressure in the pleural cavity
- alveoli expands when PP < AVP
- decreasing pleural pressure expands the alveoli
- increasing alveolar pressure expands alveoli
- pleural pressure is lower than alveolar pressure because of suction effect
- Pleural Pressure
caused by fluid removal by lymphatic system and by lung recoil
- as lungs recoil, the visceral and parietal pleurae tend to be pulled apart
- this pull decreases pressure in the pleural cavity
SUCTION EFFECT –
process of measuring volumes of air that move into and out of respiratory systems
SPIROMETRY
– measures of amount of air movement during different portions of ventilation
Respiratory volumes
sums of 2 or more respiratory volumes
Respiratory capacities –
– rate at which lung volume changes during direct measurement of vital capacity
FORCED EXPIRATORY VITAL CAPACITY
major area of gas exchange
Alveoli –
volume of areas of respiratory passageways where gas exchange does not occur (trachea, bronchi, bronchioles)
Anatomical dead space –
FACTORS influencing gas exhange
surface area
partial pressure
respiratory membrane thickness
pressure exerted by a specific gas in a mixture of gases such as air
- PARTIAL PRESSURE –
collapse of lungs
pneumothorax
– hemoglobin with oxygen bound to its heme groups
Oxyhemoglobin
Normal rate of breathing
•
Adults: 12 – 20 breaths/min
• Children: 20 – 40 breaths/min
determined by number of times respiratory muscles are stimulated
Rate of breathing –
Medullary Respiratory Center – generates the basic pattern of spontaneous, rhythmic breathing
Medullary Respiratory Center –
- longitudinal column of cells bilaterally in the dorsal part of medulla oblongata
- stimulating contraction of diaphragm
• Dorsal respiratory groups (2)
- longitudinal column of cells bilaterally in the ventral part of medulla oblongata
- stimulating external/internal intercostals and abdominal muscles
• Ventral respiratory groups (2)
part of ventral group, establish the basic rhythm of breathing
Pre- Botzinger complex –
– collection of neurons in the pons
- has connection with Medullary Respiratory Center
- plays a role in switching between inspiration and expiration
Pontine Respiratory Group
supports rhythmic respiratory movements by limiting extent of inspiration
Hering-Breuer reflex –
increase in CO2 level, results in a powerful urge to breather
Hypercapnia
decrease in O2, aortic and carotid bodies strongly stimulated
Hypoxia –
EFFECT OF EXERCISE ON BREATHING
- Rapid increase
2. Gradual increase
highest level of exercise that can be performed without causing a significant change in blood ph
Anaerobic threshold –
GENERATION OF RHYTHMIC BREATHING
- neurons in MRC are constantly active
- MRC receives much stimulation from different sources
- stimulation can come from parts of brain concerned with respiratory movements
- STARTING INSPIRATION
GENERATION OF RHYTHMIC BREATHING
- once inspiration begins, more and more neurons are activated
- result: progressively stronger stimulation of respiratory muscles, lasts for 2 s
- INCREASING INSPIRATION
GENERATION OF RHYTHMIC BREATHING
- neurons for stimulating are also the neurons for stopping
- lasts for 3 s
- STOPPING INSPIRATION
