57 Neural Control of Respiration and CV Flashcards Preview

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Flashcards in 57 Neural Control of Respiration and CV Deck (29)
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1

What does the CAROTID BODY (peripheral chemoreceptor) detect for RESPIRATION?
What does the CENTRAL chemoreceptors detect for RESPIRATION?

Carotid body: PaCO2, pH, PaO2 (mostly PaO2)
Central: PCO2 and pH

2

What does the CAROTID SINUS detect for CARDIOVASCULAR feedback?

Blood pressure

3

Note: we need blood FLOW, but we regulate blood PRESSURE

.

4

What brainstem tract is involved in signals from the carotid body and the carotid sinus?

Nucleus Tractus Solitarius (NTS)
However, the neurons from each are separate.

5

What are some examples of "higher" CNS areas that influence the respiratory and cardiovascular systems (4)?

Insular Cortex
Amygdala
Paraventricular Nucleus
Lateral Hypothalamus

6

What are brainstem tracts and nuclei that are involved in respiratory and cardiovascular systems (6)?

Nucleus Tractus Solitarius (NTS)
Nucleus Ambiguus
Rostral VentroLateral Medulla (RVLM)
Caudal VentroLateral Medulla (CVLM)

also: Periaqueductal Gray, and Parabrachial Region

7

What are intrinsic regulators of the heart and blood vessels?
What aspects of the heart and blood vessels are regulated by the brainstem?

Intrinsic: pacemakers and autoregulation of pressure
Extrinsic: contractility and vascular smooth muscle tension

8

T/F The heart will keep beating if the head is cut off, but the lungs will stop breathing.

True. Respiration requires the brainstem as its 'pacemaker.'

9

What is SUDEP?

Sudden Unexpected Death in Epilepsy
Cause unknown. Possibly apnea, hypoxemia, and altered sympathetic regulation.

10

How do emotions affect heart rate and even sudden death?

Emotions through the amygdala can affect heart rate and even cause death
Extreme sympathetics can affect ventricular fibrillation
Extreme parasympathetics can cause extreme bradycardia (Note: keep these patients supine for increased venous return)

11

Describe SYMPATHETIC activity and BLOOD PRESSURE in
non-REM and REM sleep stages.

In NREM, sympa and blood pressure DECREASE
In REM, there are SPORATIC INCREASES of sympa and blood pressure.

12

Describe the circumstances of circadian sudden death?

Peaks at 4 to 6 AM when the combination of sympathetic activity increases (to wake you up) plus REM sleep stage increases sympa and blood pressure

13

Explain the sympathetic hypertension theory.
Name one example of intermittent stress (note: this is a physical stress, not a social stress)

Intermittent high stress leads to vascular smooth muscle contraction.
Eventually, this contraction leads to hypertrophy of the smooth muscles and heart.
This permanently increases blood pressure.
e.g. Sleep apnea

14

What are the three clusters of neurons in the brainstem that control respiration?

Pontine Respiratory Group (PRG)
Dorsal Respiratory Group (DRG)
Ventral Respiratory Group (VRG)

15

What makes up the Pontine Respiratory Group?

Parabrachial and Kolliker-Fuse nuclei in the rostral dorso-lateral pons

16

Where is the Dorsal Respiratory Group?

NTS

17

What is part of the Ventral Respiratory Group?

Nucluus Ambiguus
Pre-Botzinger complex

18

All together, what are the three clusters of neurons and their locations and subgroups in the brainstem that control respiration?

Pontine Respiratory Group (PRG): Parabrachial and Kolliker-Fuse nuclei in the rostral dorso-lateral pons
Dorsal Respiratory Group (DRG): NTS
Ventral Respiratory Group (VRG): Nucluus Ambiguus and Pre-Botzinger complex

19

What is the proposed "pace maker" of the respiratory rate?

the Pre-Botzinger complex

20

What is the roles of the hypoglossal and genioglossal in respiration?

Keep the tongue out of the way

21

What are the general inputs to the brainstem for feedback regulation of respiration rate (4)?

Carotid body: PaCO2, pH, PaO2 (mostly PaO2)
Central: PCO2 and pH
Vagus: lung and airway receptors
Chest wall: muscle receptors

22

Extra credit: What are the locations of the presumed central chemoreceptors for respiration (7)?
(The point is that they are spread out over many areas)

RTN: Retrotrapezoid nucleus
Medullary Raphe
Nucleus of the Solitary Tract (NTS)
Locus Ceruleus
Fastigial Nucleus of the Cerebellum
Rostral Aspect of the Ventral Respiratory Group (VRG)
Hypothalamic Orexin neurons

23

Explain three examples of "higher" brain centers overriding the brainstem respiratory rate.

1) Sleep can cause hypoventilation and apnea (even without obstruction)
2) Emotion can cause hyperventilation
3) Volition can override breathing rates via corticospinal tracts

24

Explain the numbness and tetany that is caused by hyperventilation.

Numbness and tingling of the fingers and carpopedal spasm (tetany) are caused by decreased plasma Ca ions from respiratory alkalosis which causes Ca bindng to plasma proteins

25

What is Sudden Infant Death Syndrome (SIDS)?
What age is peak?
What neurotransmitter deficiency?

Peak incidence at 2-6 months due to cardiovascular and/or respiratory failure
Serotonin deficiency is indicated
Overall cause remains unkown

26

Summary 1:

Summary 1: The heart beat originates at the SA node but cardiovascular function and blood pressure regulation depend on an autonomic control system that modulates sympathetic and parasympathetic activity to heart and resistance vessels based on feedback from the baroreceptors that detect changes in blood pressure. We monitor and regulate the blood pressure.

27

Summary 2:

Summary 2: Respiration originates within medullary neurons that drive motor output via the phrenic nerve to diaphragm and other respiratory muscles. The level of ventilation is determined by a control system the modulates respiratory motor activity based on feedback from chemoreceptors in the carotid body and in the brain. We monitor and regulate the PaCO2.

28

Summary 3:

Summary 3: The basic brainstem neuron groups involved in these two control systems are located close together but are not identical. The NTS receives afferent input from carotid body and carotid sinus. The source of sympathetic control is the RVLM. The nucleus ambiguous contains most respiratory neurons a subset of which may be the respiratory pacemakers.

29

Summary 4:

Summary 4: Neuronal activities from parts of the CNS rostral to the brainstem can impinge upon these brainstem cardiorespiratory control sites and cause mischief. Seizures represent an abnormal form of neuronal activity, which can cause death presumably via cardiorespiratory effects (SUDEP). Profound emotional experiences can also cause death. Sleep is associated with cardiorespiratory events of surprising malevolence.