L51 Autonomic Control Circuits

Question 1

define micturition.

Answer 1

urination, passage of urine

Question 2

define Zeitgeber.

Answer 2

environmental signal which triggers the circadian clock

light with an intensity of more than 3000 lux is the most potent circadian zeitgeber

Question 3

what do parasympathetics do to the pupil?

Answer 3

constrict

midbrain –> ciliary ganglion –> short ciliary n.

Question 4

what do sympathetics do to the pupil?

Answer 4

dilate

*hypothalamo-spinal fibers important here + for motor efferents

Question 5

where do the hypothalamo-spinal fibers originate and where do they head?

Answer 5

• in the hypothalamus and descend to the upper thoracic intermediolateral cell column level of the spinal cord
• they exit to reach the superior cervical ganglion and post ganglionics constrict the pupil

Question 6

what does disruption of the descending peripheral sympathetic division of the pupil result in?

Answer 6

tonically constricted pupil

Question 7

what are the 3 levels of control of the urinary bladder?

Answer 7

1. supratentorial = frontal cortex (motor strip) + hypothalamus
2. Subtentorial = pontine micturition center
3. spinal =
   - lower thoracic and upper lumbar - sympathetic
   - midsacral - parasymapthetic + somatic (voluntary)

Question 8

where does bladder control originate?

Answer 8

frontal cortex (motor strip) and hypothalamus

Question 9

what controls micturition

Answer 9

the pontine micturition center

Question 10

where do the sympathetic efferent originate wrt autonomic control of the bladder?

Answer 10

in the lower thoracic/upper lumbar segments

Question 11

what role does sympathetics have on the bladder?

Answer 11

relax detrusor
constriction of internal sphincter

allows for filling

Question 12

where do the parasympathetics efferent originate wrt autonomic control of the bladder?

Answer 12

sacral segments

Question 13

what role does the parasympathetic have on the bladder?

Answer 13

constriction detrusor
relaxation of internal spinster

allows for emptying

Question 14

where do somatic efferents originate wrt autonomic control of the bladder?

Answer 14

sacral segments

Question 15

what role does somatic efferents have on the bladder?

Answer 15

relax the external sphincter which allows for emptying

Question 16

describe filling of the bladder.

Answer 16

sympathetic innervation maintains the detrusor relaxes and the internal sphincter constricted to allow filling

Question 17

describe emptying of the bladder.

Answer 17

• sensory afferents (soma in DRG) int he bladder wal relay info back to the ventral horn of S2-4
• they synapse on both parasympathetic efferents - one to detrusor and one to internal sphincter
• info is also relayed back to high centers (pontine micturition center) and the cortex to reach out consciousness – the cortex and the pons provide meaningful bladder control

Question 18

what are the 2 major levels of control of autonomic control of reproductive organs?

Answer 18

brain and spinal cord

Question 19

what is the brains role in the control of autonomic control of reproductive organs?

Answer 19

contributes to sexual arousal via erotic stimuli including visual, olfactory and somatosensory

Question 20

what is the spinal cords role in the control of autonomic control of reproductive organs?

Answer 20

• receives sensory input from the genitalia and descending input from the brain
• also controls reproductive function via ANS efferents
• -sympathetic - prostate gland (ejaculation), uterine and vaginal walls (contraction)
• -parasympathetics - vagina, clitoris and erectile tissue of the penis

Question 21

define circadian rhythm?

Answer 21

periods of activity alternate with period of inactivity

Question 22

what is an example of a physiological parameter that will vary as the active and inactive periods vary?

Answer 22

body temperature

*it does not follow the sleep wake cycle exactly, but the temperature of the body begins to rise as the person approaches their time of awakening triggered by the “internal clock”

Question 23

daily activity patterns persisted in the absence of ____ hence the concept of “Internal clock”.

Answer 23

external time cues

Question 24

the clock ____ precisely represent the exact 24-hour cycle of a calendar day.

Answer 24

does NOT

Question 25

why does the internal clock drift to the right?

Answer 25

because the clock is slow running on an average of 25-hour days

Question 26

in the absence of external time cues, the biological clock ____ maintain precise timing.

Answer 26

CANNOT

Question 27

what is the “home of the biological clock” and the very thing that generates rhythmic output and resets every morning at the onset of light?

Answer 27

suprachiasmic nucleus

Question 28

what activates the clock?

Answer 28

light sensitive cells in the retina (different from your average photoreceptor)

Question 29

the signal from the light sensitive retina cells is sent via _____ and synapse in the suprachiasmic nucleus.

Answer 29

retino-hypothalamic tract

Question 30

neuronal output from the suprachiasmic nucleus controls ____ from the pineal gland.

Answer 30

melatonin –“dark hormone”

Question 31

what does melatonin influence?

Answer 31

metabolic rate

Question 32

humoral output form the suprachiasmic nucleus may also include rhythmic secretion of?

Answer 32

ADH

Question 33

describe Horner’s syndrome.

Answer 33

unilateral myosis

• ptosis
• facial anhydrosis
• facial flushing
• due to underactive ipsilateral sympathetic outflow

Question 34

what are the possible causes of Horner’s syndrome?

Answer 34

• lesion/transection of the hypothalamospinal pathway in the cervical region
• preganglionic lesion (on the chain)
• postganglionic lesion at the level of the internal carotid (tumor in cavernous sinus)

Question 35

describe automatic bladder.

Answer 35

• some its with spinal cord transections will regain sacral reflexes
• in this case, the reflex to empty the bladder recovers and when the bladder reaches threshold, the reflex response will spontaneously empty the bladder

Question 36

describe atonic bladder.

Answer 36

• dorsal nerve root lesions interrupt afferent sensory fibers making the pt lose the sensation of fullness
• as the bladder fills, a constant dribbling will occur

Question 37

describe jet lag.

Answer 37

dark/light cycle no longer parallels the endogenous circadian clock system typically causing temporary insomnia which is sometimes treated with mild dose of melatonin prior to falling asleep

Question 38

describe the sleep/wake disorders in the blind.

Answer 38

• very common in the absence of visual input (zeitgeber)

- pacemakers are not entrained to social cues and suffer from sx similar to jet lag

Question 39

describe SAD.

Answer 39

• “winter depression” changing moods and sleep patterns

- due to daylight changes and its tx with light therapy to suppress melatonin synthesis