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Stack #215520
Neuro Unit II Lecture 8
| Question | Answer |
|---|---|
| Where are the cell bodies of the autonomic preganglionic neurons? | In the intermediolateral nucleus in the intermediate zone of the sc |
| How do pregan autonomic neurons leave the sc? | via the ventral root |
| Where do pregang autonomic neurons that have left the spinal cord and gone through the spinal nerve go to next? How do they get in? Because this is in the thoracolumbar area, what kind of Autonomic neurons are these? | To paravertebral ganglia. Enter via the white ramus; they are Sympathetic (SNS) |
| What happens in the paravertebral ganglia? | A symp neuron synapses and becomes postganglionic. It exits via the gray ramus. |
| Is the white ramus mylinated or unmylinated? What about the gray? | WHite=myelinated, gray=unmyelinated |
| Where are the paravertebral ganglia? What is another name for them? | bilateral to the spinal column and are cld the chain ganglia |
| Where do you find prevertebral ganglia? What do they innervate most? | In front of the spinal column. Mostly innervate abdominal viscera |
| What are three examples of prevertebral ganglion and where are they? | Celiac (most common), Inferior Mesenteric (below celiac plexus), Inferior hypogastric (below infer. mesenteric) |
| What happens when you want to urinate voluntarily (besides urinating....)? | Relaxation of the external urethral sphinc. which is skeletal muscle. Emptying assisted by the tilt of the bladder and contration of bladder smooth muscle |
| What can stop urination mid stream? | pelvic floor muscles. (Kegel exersizes) |
| How does urination occur, step by step? | Pumpkin shaped bladder stands up -> eus opens bladder contracts -> bladder falls forward when almost empty -> eus closes when bladder is almost empty |
| What is the volume in the bladder that is left after urination called? If this amount is high what happens? Who does this frequently happen to? | residual volume; causes increased urgency; frequently happens to older men with enlarged prostates |
| What is the trigone? What innervates it? What NT does it respond to? | The smooth muscle b/w where the ureters enter @ the base of the bladder. When contracted, it contracts the bladder outlet (helping you "hold it". SNS efferents and contracts w/ NE |
| Why is the SNS efferent innervation of the trigone especially important in males? | Contraction stops the semen from entering bladder |
| Where does the SNS innerv. to the trigone come from? | THe inferior mesenteric plexus OR Inferior hypogastric plexus. |
| What innervates the detrusor muscle? Where does the parasymp. innerv. come from? What does the detrusor muscle do? | SNS AND PNS efferents - from pelvic nerves 2-5. When contracted, it empties the bladder |
| What does NE do to the trigone? To the detrusor? What about Ach? | NE sim trigone, relax detrusor. Ach stim detrusor |
| What other type of innervation occurs in the bladder, specifically in the eus? What nerves carry this signal? | Somatic innerva. of the eus via the pudendal nerves |
| What are the two phases of the mituration relfex? | filling and voiding |
| What happens during the filling phase of micturation? | At first, filling causes very little change in pressure. After a while, pressure begins to increase with filling until it reaches the micturation threshold |
| What happens during the voiding phase of micturation? | Detrusor muscle contracts (Ach), pelvic floor and eus relax and urine is forced out |
| What happens to the stimulus of the eus when micturation voiding phase is going to begin? | The stimulus carried by the pudendal nerves stops and the sphincter relaxes. When its done, the stimulus begins again. |
| Where are reflex centers for micturation located? | In the brain and spinal cord. |
| What are the reflex centers of the sc (spinal centers) and what is their affiliated innervation? | Sacral center - parasymp. Lumbar center - SNS |
| What centers control the spinal centers? Where are they located? what signals do they send the spinal centers? | Supraspinal centers in the brainstem (ie Pontine micturation center), they both facilitate and inhibit spinal centers |
| What controls the supraspinal center? What signals do they send? | Diancephalic and cortical centers. Provide voluntary initiation of micturation |
| Neural pathwy for filling: | All caused by pontine micturation center. Pressure sensitive neurons not activated 1. autonom afferents showing bladder not full 2. SNS NE from lumbar cord to detrusor (-) and trigone (+) |
| 3. Somatics pudendal actively stim. eus to contract | |
| Neural pathway for voiding: | 1. b/c of dianceph/cerebral centers: VOLUNTARY - Pontine mic center stops somatic and SNS activation b/c pressure sensitive neurons go off. |
| 2.NO NE - detrusor not inhib. and trigone and eus relaxes | |
| 3. PSNS activated, Ach released and detrusor contracts | |
| Why does the micturation reflex occur in the absence of Pontine micturation center (ie spinal cord injury) | Due to the presence of the pathways still in the spinal cord. Pressure sensitive neurons can still stim. the reflex to occur |
| What is the period directly after spinal cord injury where there is no micturation relfex, reguardless of lesion location? | spinal shock (can last several weeks) |
| Any Dysfunction of the bladder caused by sc lesion is called? | neurogenic bladder |
| If transect sc above lumbar region, get this kind of bladder? What other situation can cause this kind of bladder? | automatic bladder; loss of pontine micturation center via UMN lesion. LOSE VOLUNTARY CONTROL! |
| If transect spinal cord in sacral region what kind of bladder do you get? | atonic or flaccid bladder |
| What does a normal bladder have that an uninhib (automatic) or a flaccid bladder don't have? | compliance |
| Explain what happens with the phases of micturation with a autonomic bladder. | SNS and PNS intact. When blad fills and reaches threshold, it CAN empty, but EUS must relax first(patient tapping on his bladder to cause it to relax) There is no way for the patient to inhibit the mict. reflex from occuring once threshold is reached. |
| Explain what happens with the pahses of mixturation with a flaccid bladder. | W/flaccid bladder, there is no mic reflex at all. Bladder lacks tone and cannot contract. |
| What centers inhibit bladder emptying? What ones facilitate it? | SNS efferents inhibit, PNS efferents facilitate |
| What sensations can the PNS carry in its AFFERENTS from the bladder? | Can carry some distension, painful signals |
| What sensations can the SNS carry in its AFFERENTS from the bladder? | Distension/pain |
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