Breathing

Question 0

Seizures and cardiac regulation

Answer 0

Temporal lobe -> disrupted control

• > hypoxia (50%), apnea
• > increased excitability -> PVCs, Vtach, Vfib
• > Sudden Death of Epilepsy (SUDEP) - 13:1000 pt yrs

Question 1

Physiology of cardiac control

Answer 1

System is autorhythmic, autoregulating
- CNS modulates HR, contractility, TPR, hormones

Carotid sinus IX, aortic X (baroreceptors) ->
Nucleus solitarius (NTS) ->
- nucleus ambiguous -> vagus -> HR
- caudal ventrolateral medulla (depressor)
-inhibits> rostral ventrolateral medulla (pressor)
- direct to rostral VL (pressor) -> SNS -> contractility, TPR
- A1 -> PVN, SON of hypothalamus -> vasopressin

Input from higher centers (insula, amygdala, lateral hypothal, PVN)

Question 2

Emotions and cardiovascular control

Answer 2

Input from insula, central nucleus of amygdala
Sudden death from stimuli:
- cannot ignore + excitement or giving up
- loss or threat of loss, anniversary of death
- loss of self esteem
- danger
- triumph

Excessive SNS -> Vfib
Excessive PNS -> vasovagal syncope -> death?

Question 3

Sleep and cardiovascular control

Answer 3

NREM - lower SNS -> lower BP
REM - bursts of SNS -> higher BP

Circadian death - often peaks at 4-6 am -> increasing REM, SNS

OSA -> HTN
- example of intermittent stress -> SNS -> hypertrophy

SIDS - peaks at 2-6 months
- serotonin deficiency -> ?mechanism?

Question 4

Physiologic control of breathing

Answer 4

Initiated in brainstem (pacemaker vs network) -> somatic efferents
Close proximity but diff neurons from cardiac

Chemoreceptors - peripheral (O2, CO2, pH)
- central (CO2, pH) - widely distributed (cerebellum, hypothal, etc)
CNS
- NTS/solitary/”dorsal respiratory group” - afferent
- pontine respiratory group
- rostral dorsolateral pons - Kolliker-Fuse, parabrachial
- ventral respiratory group/column
- nucleus ambiguous, Botzinger
- pre-Botzinger (-> rhythm) - bet ambig, inf olive, CNX, trigem
Output: phrenic (somatic)
- also hypoglossal -> tongue and airway

Question 5

Cortical modulation of breathing

Answer 5

Sleep - highly variable, may have apnea (with or without obstruct)
- hypoventilation - CO2 doesn’t stimulate drive
Emotion - amygdala -> hyper vent -> high pH -> Ca++ binds -> spasms
Volition

OSA - decreased tone of genioglossus -> airway collapse

• still have cyclic pressure changes
• males, HTN, BMI