Lecture 19 Flashcards
What is called the ability to maintain respiratory rhythm to suit body’s needs
Regulation of respiration
Two types if respiratory regulations
- Neural regulation
- Chemical regulation
Components of neural regulation
- respiratory center
- cortex
- hypothalamus
Components of chemical regulation
- central chemoreceptors
- peripheral chemoreceptors
The respiratory center (RC) is and does what
Is groups of neurons in hind part of brain and regulates rate and depth of breathing
RC is located in two regions of brain:
- Medulla
- Pons
Medulla (expiratory and inspiratory center) function
Can regulate both expiration and inspiration depending on the neurons activated
Pons areas function
- can decrease duration of inspiration which will alter respiratory rate
- can send signals for deep long breaths
Why can we voluntarily alter our pattern of breathing
Bc cerebral cortex has connections with respiratory center
Why is voluntarily breathing control protective
We can prevent breathing water or gas
The basic rhythm of respiration can be modified by
Inputs from other brain regions, receptors in peripheral nervous system and other factors
What can the involuntary breathing system override
The voluntary one (can’t kill yourself by holding breath)
When holding breath and fainting, what happens when consciousness is lost
Breathing restarts
Breathing automatically resumes if what increases to a certain level (and stimulate inspiratory area which sends impulses to phrenic and intercostal nerves)
[Pco2 and H+]
Where are located central chemoreceptors
Medulla
Central chemoreceptors respond to changes in what
H+, pco2 in cerebrospinal fluid (CSF)
When co2 from plasma enters CSF, why does ph decrease
Bc it forms HCO3 and H+
Central chemoreceptors respond to decrease in pH by
Stimulating respiratory center to increase inspiratory rate
Inc in co2 -> inc in H+, so
Dec in ph and inc in breathing rate
Where are peripheral chemoreceptors
In aortic bodies (in walls of aortic arch) and carotid bodies ( walls of carotid arteries)
What do peripheral chemoreceptors do
Monitor chemistry of blood and are sensitive to changes in po2, pco2, h+ in blood
What causes peripheral nervous system’s chemoreceptors to stimulate respiration center
Dec in ph, dec in o2, inc in co2
Dec in ph, dec in o2, inc in co2 =
Inc in breathing rate
Any rise in co2 results in rise of
Ph (bc forms carbonic acid which dissociates into h+ ions)
Name the sensory chemoreceptors receptors
-Central chemoreceptors (in medulla)
^Responds to changes in csf
-Peripheral chemoreceptors (aortic body and carotid body)
^Responds to changes in blood
What is an important secondary function of respiratory system
Regulate blood ph (by getting rid of co2
What is hypercarbia/hypercabnia
High levels of co2 in blood (only slight increase necessary)
Inspiratory center is more sensitive to rise in pco2 or fall in po2
Pco2 above normal
What feedback system do chemoreceptors participate in
Negative
Negative feedback loop by chemoreceptors how
Change in pco2/po2/ph -> Inspiratory area highly active -> breathing increases -> more o2 inhaled and co2 exhaled
Proprioceptors function
Monitor mvmt of joints/muscles as soon as exercise-> stimulate inspiratory area of medulla -> breathing inc
What are stretch-sensitive receptors in terminal bronchioles and atria called
Baroreceptors or stretch receptors
When do baroreceptors activate
When max air gets filled in alveoli
How do baroreceptors work
1.Get activated
2. It activates inflation reflex
3. Send inhibitory signal to insp center through vagus nerve
4. Nerve switches off ins and exp begins
Inflation reflex is protective mechanism how
Prevents excessive inflammation of lungs
Irritating stimuli on nasal cavity/larynx/bronchioles can initiate
Protective reflexes (cough/sneezing)
Things involved in regulation of respiratory system
- Cortex (brain)
- Respiratory center (brain stem)
- Central chemoreceptors
- Peripheral chemoreceptors
- Proprioceptors
- Inflation reflex/baroreceptors
- Irritating stimuli
How limbic system stimulation (hypothalamus) influence respiration
Anxiety or excitement can stimulate hypothalamus, sends excitatory input to insp area -> inc ventilation
How Temp influence breathing
Inc in temp (fever/exercise) inc rate. Dec in temp dec rate
How pain influence breathing
Sudden severe pain = brief apnea
Prolonged somatic pain = inc
Visceral pain = may slow rate of
Stretching anal sphincter muscle influence breathing how
Inc breathing rate, sometimes used to stimulate resp in newborns or person who stopped breathing
How irritating airways affect breathing
Physical/chemical irritation of pharynx/larynx brings immediate cessation followed by cough/sneeze
What is hypoxia
O2 deficiency at tissue level
Hypoxic hypoxia
Low po2 in arterial blood
Cause : high altitude, airway obstruction, fluid in lungs
Anemic hypoxia
Little hb functioning -> little o2 transport to cells
Causes: hemorrage, anemia, CO poisoning
Ischemic hypoxia
Reduced blood flow to tissue (less o2 delivered)
Histotoxic hypoxia
Proper blood delivery but toxic agent enabling o2 use
Cause: cyanide poisoning (blocks enzymes during o2 use for atp)
Hypocapnia/hypocarbia
Pco2 lower than 40 mmHg in arterial blood
Hypocapnia mechanism and cause
Chemoreceptors not stimulated -> no sensory impulses to insp area. Area sets moderate pace until pco2=40
Cause: hyperventilation
At higher altitude, less oxygen available meaning
Hb saturation levels are lower than normal
At higher altitude, hb affinity is reduced =
More o2 released in tissues (rise in DPG (=BPG))
Under physical stress at hight altitude tissues become
Hypoxic (not enough o2 to meet demands of tissue), breathing rate increases
What adjustment body does to adapt to high altitude
Hematopoietic adjustments
What is hematopoietic adjustments
When o2 level dec, kidneys produce more erythropoietin (hormone increasing production of RBC). Way to acclimatize to long exposure of high altitude
Nicotine effect
Constricts terminal bronchioles (dec airflow)
Carbon monoxide bad for breathing why
Binds to hb instead of o2 -> less o2 carrying capability
Irritants in smoke cause
Mucus secretion (mucosa), swelling of mucosal lining-> impede airflow
Irritants in smoke also
Inhibit mvmt of/destroy cilia -> excess mucus and debris not easily removed
With time smoking leads to
Destruction of elastic fibres in lungs and prime cause of emphysema
