(8) Control of Respiration

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what is the distinct difference between cardiac and respiratory control?

- cardiac doesn't need an external source to function
- respiratory depends on medulla to activate muscles to cause breathing

the 4 types of receptors that influence the inspiratory center are ____

- peripheral chemoreceptors
- central chemoreceptors
- lung stretch receptors
- muscle and joint receptors

the peripheral chemoreceptors are sensitive to ____ (3 things)

O2, CO2, H+

the central chemoreceptors are sensitive to ___

H+

the peripheral chemoreceptors send afferents to the inspiratory center via ______ (2 CN)

- CN IX
- CN X

the lung stretch receptors send afferents to the inspiratory center via ______ (1 CN)

CN X

the apneustic center has a(n) _____ effect on the inspiratory center

excitatory

the pneumotaxic center has a(n) _____ effect on the inspiratory center

inhibitory

the inspiratory activates the diaphragm via the _____

phrenic nerve

the respiratory center is located in the _____

pons

the VRG and the DRG are located in the ___

medulla

the respiratory group inactive during quiet breathing is _____

VRG (because responsible for expiration, which is passive at rest)

the VRG is located dorsally near the root of CN ___

IX

the DRG is a network of neurons that extends in the ventral brain stem from the spinal cord to the ______

pons-medulla junction

the VRG integrates input from the ___ and ____ receptors

- peripheral stretch receptors
- chemoreceptors

the inspiratory center is located in the _____ of neurons in the reticular formation

dorsal respiratory group (DRG)

the inspiratory center (in the DRG) is responsible for ____

rhythm (sets frequency of inspiration)

the expiratory center is located in the _____ of neurons in the reticular formation

ventral respiratory group (VRG)

the expiratory center is responsible for ____

expiration

the _____ contains rhythm generators whose output drives respiration

(is this wrong? its in the picture)

VRG

the ____ integrates peripheral sensory input and modifies the rhythms generated by the other respiratory group

(is this wrong? its in the picture)

DRG

inspiratory depth is determined by how actively the respiratory center ____ the motor neurons serving the respiratory muscles

stimulates

the greater the stimulation by the respiratory center, the ____ the number of motor units excited and force of respiratory muscle contraction

greater

respiratory rate is determined by _______

- how long the inspiratory center is active OR
- how quickly it is switched off

the peripheral chemoreceptors have a _____ effect on the respiratory centers in the medulla and pons

stimulatory

the peripheral chemoreceptors are activated by
- ___ O2
- ___ CO2
- ____ H+

- decreased O2
- increased CO2
- increased H+

the central chemoreceptors have a _____ effect on the respiratory centers in the medulla and pons

stimulatory

the central chemoreceptors are activated by
- ___ CO2
- ____ H+

- increased CO2
- increased H+

TRUE OR FALSE:
central chemoreceptors are sensitive to O2

false

receptors in joints and muscles have a _____ effect on the respiratory centers in the medulla and pons

stimulatory

the irritant receptors in the lungs have a ____ effect on the respiratory centers in the medulla and pons

inhibitory

the stretch receptors in the lungs have a ____ effect on the respiratory centers in the medulla and pons

inhibitory

higher brain centers in the _____ have a +/- effect on the respiratory centers in the medulla and pons because this is where you see ____ control over breathing

voluntary

other receptors (e.g. pain) and emotional stimuli act through the _____ to have a +/- effect on respiratory centers in the medulla and pons

hypothalamus

____ is the most potent and most closely controlled molecule

CO2

normally, arterial PCO2 is ___ mmHg

40

arterial PCO2 is normally maintained within __ mmHg of 40 mmHg

3

arterial PCO2 is normally maintained within 3 mmHg of 40 mmHg by an exquisitely sensitive homeostatic mechanism mediated mainly by the effect that rising CO2 levels have on the _____ of the brain stem

central chemoreceptors

arterial CO2 crosses the BB and ____ equilibrates with CO2 in the CSF

rapidly

H+ and HCO3 cross the BBB ____

slowly

arterial CO2 combined with metabolic CO2 to _____ smooth muscle

dilate

when compared with arterial blood, the pH of CSF is ____ and the PCO2 is ____, with little protein buffering

pH lower, PCO2 higher

increased arterial PCO2 will cause a _____ in the pH of the CSF

decreased

central chemoreceptors in the medulla will respond to ____ in the CSF

H+
(mediates 70% of the CO2 response!)

peripheral chemoreceptors in the carotid and aortic bodies will mediate ___% of the CO2 response

30

the central and peripheral chemoreceptors send afferent impulses to the ____

medullary respiratory centers

the medullary respiratory centers send efferent impulses to the ___ to ____ ventilation

respiratory muscle, increase

increased ventilation will ______ PCO2

decrease

increased ventilation and decreased PCO2 will cause arterial PCO2 and pH to return to ___

normal

in the chemosensory contributions to ventilatory drive, a stimulus of acute hypercapnia will mostly stimulate _____ and have a ____ effect on ventilation

central chemoreceptors; very large increase

in the chemosensory contributions to ventilatory drive, a stimulus of chronic hypercapnia will mostly stimulate _____ and have a ____ effect on ventilation

central chemoreceptors; large increase

in the chemosensory contributions to ventilatory drive, a stimulus of acute mild metabolic acidosis will mostly stimulate _____ and have a ____ effect on ventilation

peripheral arterial chemoreceptors, slight increase

in the chemosensory contributions to ventilatory drive, a stimulus of chronic mild metabolic acidosis will mostly stimulate _____ and have a ____ effect on ventilation

peripheral chemoreceptors, moderate increase

the only way central chemoreceptors will respond to O2 is if ____

O2 is really low

peripheral chemoreceptors are located in the _____

carotid and aortic bodies

peripheral chemoreceptors in the carotid body are innervated by ____

CN IX (pharyngeal branch of glossopharyngeal)

peripheral chemoreceptors in the aortic arch are innervated by ___

CN X (vagus)

_____ receptors are located next to capillaries, and detect fluid build-up

juxtacapillary (J) receptors

there are specialized tissues that sense the local O2 tension in the
- ___ cells of the carotid body
- ____ bodies in the lungs
- _____ cells of the fetal adrenal medulla
- ____ cells of the resistance pulmonary arteries
- fetoplacental ____
- systemic _____
- the ______ in the fetus

- glomus cells of the carotid body
- neuroepithelial bodies in the lungs
- chromaffin cells of the fetal adrenal medulla
- smooth-muscle cells of the resistance pulmonary arteries
- fetoplacental arteries
- systemic arteries
- ductus arteriosus

Specialized tissues that sense the local oxygen tension include glomus cells of the carotid body, neuroepithelial bodies in the lungs, chromaffin cells of the fetal adrenal medulla, and smooth-muscle cells of the resistance pulmonary arteries, fetoplacental arteries, systemic arteries, and the ductus arteriosus. although all tissues are sensitive to severe hypoxia, these specialized tissues respond ____ to moderate changes in O2 tension within the physiologic range (roughly 40-100 mmhg in an adult and 20-40 mmHg in a fetus)

rapidly

In the pulmonary-artery smooth-muscle cell (shown in the upper half of the figure) during normoxia, an outward potassium (K+) current, illustrated by the single channel trace that shows steplike opening and closing, keeps the membrane potential at about -50 mV or -60 mV. This hyperpolarization prevents ___ from entering the cell through the voltage-gated _____ channel

calcium, L-type calcium

____ inhibits potassium-channel activity and depolarizes the membrane to about -20 mV, permitting calcium entry.

Hypoxia

In the ductus smooth-muscle cell (lower half of the figure), by contrast, the outward potassium current is maintained during ___ and is inhibited by ____.

hypoxia, normoxia

A rise in oxygen, as at birth, then causes membrane ____ and calcium entry

depolarization

The chief function of the carotid body is to increase respiration in response to ___-

hypoxia

The proximal pathway in the type 1 cell of the carotid body is similar to that in the pulmonary-artery smooth-muscle cell. Hypoxia ____ potassium-channel activity, shown in the single channel trace, causing membrane depolarization, calcium influx, secretion, and increased action potentials in the carotid-sinus nerve

inhibits

. If the membrane potential (Em) is "clamped" at -60 mV, hypoxia no longer leads to an increase in the cytosolic calcium (Ca2+ i), indicating that the increase in calcium requires membrane _____

depolarization

Cytosolic calcium normally rises sharply as oxygen levels fall below __ mm Hg.

60

Increased calcium stimulates the release of ____, a marker for secretion. pA denotes picoamperes.

dopamine

The specialized tissues in the body that sense oxygen share a common mechanism that involves
- ____ channels
- membrane _____
- ____ calcium channels

- potassium
- potential
- L-type

In vascular smooth-muscle cells, oxygen sensing also involves calcium release from the sarcoplasmic reticulum and calcium entry through store-operated channels, as well as calcium ____

sensitization

Obstructive sleep apnea, defined as the presence of at least FIVE obstructive events (apneas and hypopneas) per hour ____

during sleep

The obstructive sleep apnea-hypopnea syndrome, defined as the presence of at least FIVE obstructive events per hour with associated ____

daytime sleepiness

Obstructive sleep apnea is found in 9 to 26% of middle-aged people without specific risk factors for the disorder, whereas obstructive sleep apnea-hypopnea syndrome is found in ___-___% of the same population

2-4

the biggest symptom of sleep apnea is ___

tiredness during the day (including falling asleep at the wheel)

patients with sleep apnea tend to ___ during sleep

snore

patients with sleep apnea tend to be ______ and ___

overweight and males

how do you diagnose sleep apnea?

sleep study

how do you treat sleep apnea?

CPAP (forces airways open)

in the "clinical features" of sleep apnea, sleep fragmentation leads to daytime ____

hypersomnolence

in the "clinical features" of sleep apnea, sleep fragmentation leads to daytime hypersomnolence, which leads to ____ (3 things)

- alteration in personality
- accidents
- performance decrements

in a sleep study test, 4 things that are monitored are ___

- HR
- impedance
- thermistor,
- SaO2

thermistors measure the ___

air

a lot of air as measured by the thermistor indicates ___

snoring

SaO2 should be _____ normally

flat

in sleep apnea, SaO2 is found to ____

go up and down

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