Lecture 25: Hypertension

Question 1

What is respiratory activity correlated with?

Answer 1

sympathetic activity

Question 2

What is sympathetic activity and heart rate modulated by?

Answer 2

respiration

Question 3

What is altered respiratory sympathetic interaction a driver of?

Answer 3

the development of hypertension

Question 4

When is co-transmission increased?

Answer 4

with irregular bursts of sympathetic activity (programs rat to become hypertensive)

Question 5

How is sympathetic activity related to respiration?

Answer 5

phase-locked with respiration

Question 6

In spontaneously hypertensive animals, sympathetic activity shows greater time-locked activity with respiration. What does this result in?

Answer 6

increased noradrenaline release from postganglionic sympathetic neurons
increased NPY co-transmission in postganglionic sympathetic neurons

Question 7

What are the three classes of motor neurons that drive respiratory muscles?

Answer 7

thoracic, abdominal and phrenic motor neurons

Question 8

Where in the spinal cord is the phrenic motor nucleus located?

Answer 8

C3-C5

Question 9

Where in the spinal cord are the intercostal motor neurons located?

Answer 9

T1-L1

Question 10

Where in the spinal cord are the abdominal motor neurons located?

Answer 10

T7-L1

Question 11

Which structures prevent breathing in of too much air?

Answer 11

stretch receptors which increase in activity as lung volume increases
send information via the nucleus of the solitary tract and inhibit inspiratory motor neurons leading to expiration

Question 11

Which group of neurons are located near nuclei involved in generating respiratory rhythm? What is their role?

Answer 11

rostral ventral lateral medulla

generate sympathetic activity to the vascular system

Question 12

What are rRVLM neurons modulated by?

Answer 12

the respiratory system

Question 13

What does contraction of the diaphragm produce?

Answer 13

increased venous return, reduced intrathoracic pressure and increased heart rate

Question 14

Because respiratory modulation of sympathetic activity continues in the absence of lungs and changes in intrathoracic pressure, what can we deduce?

Answer 14

the neurons that drive respiratory and sympathetic activity must be interacting

Question 15

What type of neurons are C1 neurons?

Answer 15

catecholaminergic

Question 16

What type of neurons are non-C1 neurons?

Answer 16

unsure

Question 17

What do C1 and non-C1 neurons contribute to?

Answer 17

the sympathetic activity that constricts blood vessels

Question 18

Sympathetic activity is time-locked with ___, particularly in ___ rats. The resulting ___ of activity result in increased ___ release and ___ in postganglionic sympathetic neurons.

Answer 18

respiration, hypertensive, bursts, noradrenaline, NPY co-transmission

Question 19

Where are C1 neurons located and what are they essential for?

Answer 19

located in the RVLM and are essential for respiratory-linked sympathetic activity

Question 20

What does deletion of C1 neurons in spontaneously hypertensive rats result in?

Answer 20

decreased blood pressure

Question 21

Why is it believed that C1 neurons are responsible for driving the development of hypertension?

Answer 21

enhanced sympathetic respiratory coupling is present in subjects who show an exaggerated BP response to moderate exercise
C1 neurons are responsible for sympathetic respiratory coupling
the number of C1 neurons in the brains of experimental animals is correlated with their BP