Exam 3 Week 13 ppt 4 ANS ventilation

Question 1

what type of function is the control of ventilation?

Answer 1

~“autonomic” function – it really is not other than bronchiolar dilation and constriction
~Control of ventilation is an automatic (non-voluntary) function but NOT autonomic

Question 2

how is the control of ventilation accomplished (though what)

Answer 2

~by a network of complex circuitry

~mostly in the medulla

Question 3

control of ventilation- visceral afferents from (and via)

Answer 3

~from the carotid and aortic chemoreceptors

~via CN IX and X which help in this regulation

Question 4

control of ventilation- output

Answer 4

somatic lower motor neurons which contact the skeletal muscle of the diaphragm and accessory ventilatory muscles

Question 5

control of ventilation- basic rhythm of breathing is produced by

Answer 5

Pacemaker like cells within inspiratory center in the Dorsal respiratory group in medulla

Question 6

control of ventilation- inspiratory neurons produce

Answer 6

Spontaneous depolarization @ about 15/min which is the basic respiratory rate

Question 7

control of ventilation- axons from inspiratory neurons follow

Answer 7

~Descending tract to C3-C5 motor neurons

~from lower motor neurons form the phrenic nerve which innervates the diaphragm via the phrenic nerve

Question 8

control of ventilation- long term respiratory rate and number of neurons activated are increased by

Answer 8

central chemoreceptor input (ventral medulla)

Question 9

control of ventilation- peripheral chemoreceptor afferents will

Answer 9

~increase the number of neurons activated (depth of breathing) and
~increase the frequency of depolarization (the rate of breathing) in the short term
(these are the afferents from the receptors in the carotid sinus and aorta. They change rate and number of activated neurons on a minute by minute basis)

Question 10

control of ventilation- increased rate of depolarization

Answer 10

~increase the rate of breathing

Question 11

control of ventilation- medullary Chemoreceptors are

Answer 11

~sensitive to elevated H+ in cerebrospinal and fluid which is produced by elevated CO2 in blood
~increased H+ in CSF increases ventilatory rate and depth of ventilation
(medullary chemoreceptors = central chemoreceptors)

Question 12

what are ways the peripheral chemoreceptors can respond to elevated H+/CO2?

Answer 12

Firing rate of neurons in medulla and number neurons activated

Question 13

peripheral chemoreceptors communicate with the respiratory center via

Answer 13

CN IX from carotid chemoreceptors and CN X from aortic chemo-receptors

Question 14

peripheral chemoreceptors are sensitive to

Answer 14

~increases in blood levels of H+/CO2- result of increased metabolic activity (exercise)

Question 15

peripheral chemoreceptors respond to

Answer 15

~minute by minute changes in blood levels of H+/CO2

Question 16

central chemoreceptors respond to

Answer 16

~long-term resting levels of H+ in the CSF (produced by elevated CO2 in the blood)

Question 17

inspiratory neurons in the medulla- threshold (will send activation where)

Answer 17

~slightly higher threshold inspiratory neurons that when activated will send descending excitatory activation to the LMNs in the cervical and thoracic LMNs
~ innervate the accessory muscles of inhalation (sternocleidomastoid, traps, intercostals)
_____________________________
1. lower threshold Inspiratory neurons in medulla that stimulate LMNs in spinal segments C3, C4 and C5 project to the diaphragm via the phrenic nerve.
2. slightly higher threshold inspiratory neurons that when activated will send descending excitatory activation to the LMNs in the cervical and thoracic LMNs that innervate the accessory muscles of inhalation (sternocleidomastoid, traps, intercostals)

Question 18

expiratory UMNs in the medulla are normally excited or unexcited?

Answer 18

normally unexcited

Question 19

how do the inspiratory and expiratory UMN interact in the medulla?

Answer 19

~Inspiratory neurons in medulla are activated= inhibit expiratory UMNs
~few inspiratory neurons activated= little inhibition of expiratory interneurons

When there is high levels of inspiratory UMN activity, there is dramatic inhibition of the expiratory UMNs. When this inhibition comes to an end, there is a rebound effect that excites the expiratory UMNs causing active exhalation using the abdominal and intercostal muscles. This is why you exhale actively during strenuous activity, but not at rest.

Question 20

expiratory neurons membrane potential returns to resting following..

Answer 20

~the release from inhibition

Question 21

very high levels of inspiratory UMN activity

Answer 21

dramatic inhibition of expiratory UMNs

Question 22

when the inhibition of expiratory UMN ends,

Answer 22

=large Disinhibitatory rebound of expiratory UMN
~produces excitation of expiratory UMNs
~produce active exhalation by exciting LMNs in the thoracic spinal cord
~innervate the muscles of exhalation (abdominals and intercostals)

Question 23

during restful inhalation

Answer 23

~not much inhibition of expiratory UMNs
~do not become active
~normally passive exhalation during restful inhalation

Question 24

two pontine centers that help regulate ventilation

Answer 24

~pneumotaxic center

~apneustic center

Question 25

Pneumotaxic center

Answer 25

~In rostral pons
~Functions as “off-switch” for inspiration
~active =shortens inspiratory duration which aids in the increased inspiratory rate

Question 26

Apneustic Center

Answer 26

~in the caudal pons

~may integrate afferent and central drives to inspiratory and expiratory UMNs

Question 27

is there any voluntary control in ventilation?

Answer 27

limited amount of voluntary control

Question 28

voluntary control of ventilation- where in brain

Answer 28

~Activity from cerebral motor cortex

Question 29

voluntary control of ventilation- produces

Answer 29

~produce voluntary increase or decrease of ventilatory rate and volumes by stimulating or inhibiting both the inspiratory and expiratory centers of the medulla

Question 30

voluntary control of ventilation- inhibits (where)

Answer 30

~can inhibit both the inspiratory and expiratory centers of the medulla

Question 31

voluntary control of ventilation- why is this important?

Answer 31

~voluntarily take a deep breath and slowly let it out as in talking or use expiratory neurons to quickly exhale as in blowing out birthday candles or yelling at a high volume

Question 32

control of ventilation- increased number of neurons causes what?

Answer 32

increased depth of breathing