11 2. GangliaOvoid structures containing neuronal cell bodies and glial cells supported by connective tissueThe direction of the nerve impulse determines whether sensory or autonomic ganglia.
12 Sensory ganglia: receive afferent impulses that go to the CNS Cranial ganglia: cranial nervesSpinal ganglia: dorsal root of spinal nervesAutonomic ganglia:Sympathetic: paravertebrate, preveterbrateParasympathetic: close to organs or in organs
13 3. Nerve ending Sensory nerve ending Motor nerve ending Free: pain, temperatureencapsulateMotor nerve endingMotor end plateVisceral motorTactile corpuscle: sense of touchLamellar corpuscle: pressure, vibrationMuscle spindle: limbs position
14 Tactile corpuscleLamellar corpuscleMuscle spindleMotor end plate
15 Autonomic nervous system The ANS consists of motor neurons that:Innervate smooth and cardiac muscle and glands (most of the effectors are viscera)
17 Three major differences in the ANS and SNS EffectorsEfferent pathwaysTarget organ responses
18 Effectors The effectors of the SNS are skeletal muscles The effectors of the ANS are cardiac muscle, smooth muscle, and glands
19 Efferent PathwaysMyelinated axons of the somatic motor neurons extend from the CNS to the effector (lacks ganglia)Pathways in the ANS are a two-neuron chainThe preganglionic (first) neuron has a lightly myelinated axon. The ganglionic (second) unmyelinated neuron extends to an effector organ via the postganglionic axon
20 Neurotransmitter Effects All somatic motor neurons release Acetylcholine at their synapses, Ach always has an excitatory effectIn the ANS:Preganglionic fibers release AChPostganglionic fibers release norepinephrine (most s.) or ACh (p.) and the effect is either stimulatory or inhibitory
22 The nuclei of the Sym. are located in the thoracic and lumbar segments of the spinal cord. The 2nd neuron is located in sensory ganglia.The nuclei of the Para. are located in the medulla and midbrain and in the sacral portion of the spinal cord.The 2nd neuron is in ganglia located near or within the effector organs
23 II. The central nervous system CerebrumCerebellumSpinal cordCNS has almost no connective tissue,A relatively soft gel-like tissue.
24 White matter Gray matter Myelinated nervous fibers and oligodendrocytesGray matterNeuronal cell bodiesdendritesInitial segmentGlial cells
25 1. CerebrumThe gray matter forms cortex, the white matter forms medulla.Cerebral cortex has six layers of cells
26 Sensory inputs first activate neurons in layer 4, which propagate the excitement up to layer 2,3, and down to layer 5,6
27 2. Cerebellar cortex has 3 layers Out molecular layerPurkinje cells layerInner granular layerPurkinje cells are the efferent neuronsMossy and climbing fibers are afferent fibers