unit1.4 nervous system

Question 1

explain the difference between CNS and PNS

Answer 1

CNS-brain and spinal cord

1. brain-cerbrum, cerebellum and brainstem
2. some motor fibers of cranial nerve (PNS) have somas located in the brainstemCNS

PNS-nerves, pluxes and ganglia

1. some motor fibers of spinal nerves have somas located in the spinal cordCNS

Question 2

what tissue type and layers are the meninges?

Answer 2

three membranous layer of connective tissue(fascia)

1. pia matter
2. arachnoid matter
3. dura matter

continuous with CT covering of peripheral nerves

Question 3

diagram the PNS ganglia

Answer 3

ganglion-collection of neuronal soma outside the CNS

1. contribute to all sensory and some motor components
   
   1. Dorsal root ganglia(sensory)
   2. cranial nerve ganglia (sensory) ***not in diagram***
   3. autonnomic ganglia(motor)

Question 4

describe the general systems of the nervous system give examples

Answer 4

nervous system is based on target of innervation-the nervous system has two divisions

1. somatic(voluntary)
   
   1. innervation of skin, some fascia, tendons, joints, bones and SM
   2. voluntary and reflexive movment
   3. somatic sensation (touch, pain, temp, proprioception)
2. visceral(nonvoluntary)
   
   1. innervation of smooth muscle (including blood vessels), cardiac muscle, glands and visceral fascia
   2. involuntary motor functions(gut, peristalsis, constriction,
   3. visceral senation-pain, chemoreceptin, mechanoreception, distension

Question 5

diagram and define neruon route in the spinal cord/ganglia

Answer 5

1. gray matter
   
   1. ventral horm
      
      1. soma of somatic motor
   2. lateral horn
      
      1. soma of preganglionic visceral motor neurons
   3. dorsal horn
      
      1. receive central process of somatic sensory neurons, NO SENSORY NEURON SOMA
2. spinal ganglia
   
   1. soma of BOTH somatic and visceral sensory neurons

Question 6

What nerves make up the spinal cord nerves? general. diagram

Answer 6

a typical spinal nerve is a mixed nerve containing both sensory(afferent) fibers and motor(efferent) fibers from one segment off spinal cord, formed by the union of : posterior (dorsal)root and anterior(ventral) root. the roots are formed by rootlets.

Question 7

dicuss the innervation sites for rami

Answer 7

short spinal nerved

1. posterior(dorsal) primary ramus
   
   1. supply structures intrinsic muscles of the back
2. anterior(ventral) primary ramus
   
   1. innervate anterolateral body wall, extremities and superficial back muscles

Question 8

generate a flow chart starting from the posterior/anterior rootlets

Answer 8

Question 9

Efferent neurons are part of what system? diagram location in spinal cord and synapse location

Answer 9

1. efferent neurons
   
   1. multipolar-many drendrite, one axon
   2. soma located in the ventral horn
   3. synapse on skeletal muscle

Question 10

afferent neurons are part of what system? diagram location in body and synapse location(s)

Answer 10

sensory neurons

1. psudounipolar
2. soma is located in the dorsla root ganglion
3. peripheral process tha synpase on sensory receptors, carry information toward cell body
4. central process synapses on neurons in the doral horn of the spinal cord
   
   1. carries action potentials away from the cell body toward the CNS.

Question 11

Discuss function and location of GSA and GSE

Answer 11

GSA-general somatic afferent

1. somatic sensory nerve fibers carry info from
   
   1. skin, fascia, SM, bones, tendons and ligament
2. position sense from SM, tendons and joints

GSE-general somatic effernt

1. somatic motor nerve fibers control the contraction of SMfibers

Question 12

Describe innervation of strips of skin

Answer 12

Dermatones-GSA in each spinal nerve supply a particular strip of skin.

1. face and scalp are exception
   
   1. innervated via cranial nerves

Question 13

Discuss function and location of GVE and GVA

Answer 13

GVE: general visceral efferent

1. visceral motor/efferent nerve fibers control the activities of smooth muscle(organs vasculature, hairs), CM and glands
2. sympathetic and parasympathetic

GVA; general viscerla afferent

1. visceral sensory/afferent nerve fibers accompany visceral efferent fibers* especially those that supply the heart and various organs(viscera)

Question 14

describe the travel of GVE and GVA from organs and spinal cord

Answer 14

GVA accompany GVE from the viscera.

• GVA fibers that carry pain from viscera usually accompany sympathetic GVE fibers
• other GVA sensations accompany parasympathetic GVE fibers.
• soma of GVA is located in dorsal root ganglion
• soma of GVE are located in the two places (ventral horn and autonomic ganglion)

Question 15

diagram the soma and continuation of motor fibers in the GSE and GVE

Answer 15

1. the somatic motor system has a one-neuron lkinkage between the CNS and effector;
2. the autonomic motor system has two-neuron linkage
   
   1. composed of preganglionic and postganglionic neurons
      
      1. preganglionic soma is in lateral horn
      2. post ganglionic soma is in autonoic ganglia

Question 16

diagram preganglionic and postganglionic neurons of sympathetic nervous system

Answer 16

• thoracolumbar division of the ANS> preganglionic neuron cell bodies in the lateral horn of spinal cord segments T1-L2
• post ganglionic neurons soma located
  
  • paravertebral ganglia
    
    • each side of vertebral column in sympathetic trunk from C1-Co>thoracic viscera, limbs and body walls
  • prevertebral ganglia
    
    • on abdominal aorta>abdominal and pelvic viscera

Question 17

list path of GVE nerurons starting with soma ending are target.

Answer 17

GVE preganglionic fibers travel from lateral horn through the ventral root->spinal nerve->paravertebral ganglionof the sympathetic trunk (via white ramus-only for SYMPATHETIC nerves).Once inside the paravertebral ganglion the GVE preganglionic fibers can go one of two paths

1. synapse with postganglionic neuron
   
   1. ​GVE postganglion fibers leave the paravertebral gangliion via gray rami communicantes to re-enter the spinal nerve toward limbs and body wall.
      
      1. pilo erection, vasoconstriction, secretion
2. pass through to go to prevertebral ganglia
   
   1. ​GVE postganglionic fibers pass through prevertebral gangliin as splanchnic (visceral) nerves to the viscera
      
      1. internal organs

Question 18

discuss preganglion fibers of the SNS

Answer 18

preganglionic fibers can travel up and down the chain of paravertebral ganglia (sympathetic trunk) to reach ganaglia beyond lecel T1-L2

Question 19

when you get red/ pale what is happening to your sympathetic tone?

Answer 19

red, hair relaxed=more blood going to the skin, less sympathetic tone

pale, sweating, hair standing=less blood going to the skin, high sympathetic tone

Question 20

Diagram and define organization of ANS with respect to PNS.

Answer 20

1. craniosacral division of the ANS due to the location of its preganglionic cell bodies for the parasymathetic nervous system
   
   1. brainstem
      
      1. ​travel in cranial nerves
   2. lateral horn of S2-4
      
      1. ​travel in spinal nerves and exit as splanchnic (visceral) nerves to go to viscera
   3. NEVER GO TO SYMPATHETIC TRUNK
2. Post ganglionic neurons cells bodies located in intramural ganglia

not found in the walls of limbs

Question 21

what is a splanchnic nerve. describe nerve types that have action on viscera

Answer 21

post ganglionic viscera nerve. GVA and GVE

1. GVE
   
   1. sympatheic fibers that leave paravertebral ganglia and do one of two things
      
      1. preganlionic fibers– to prevertebral ganglia to synapse
      2. postganglionic-going to viscera(cardiac nerve), continue through
   2. parasympathetic fibers
      
      1. are always preganglionic fiber wich synapse
      2. somas branch from spinal nerves to go to viscera

only postganglionic sympathetic fibers of parasympathetic fibers have an action on the viscera

never go to the periphery, they only deliver to and from the viscera.

Question 22

Answer 22

other sympathetic fibers that do not travel in or reenter spinal nerves will be considered later

Question 23

what generates the structure of a nerve plexus

Answer 23

a nerve plexus is formed by axons coming from different spinal nerves that intermingle to give terminal nerves containing fibers from more than one spinal level.

there are somatic and visceral nerve plexuses.

Question 24

describe a reflex and diagram neuronal connections

Answer 24

reflex-involunvtary steretyped motor response to a particular sensory stimulus

reflex arch -comprises of afferent limb, an efferent limb, and usually one or more interneurons (relay)

1. refelxes can be somatic or visceral