Memmler’s A&P Chap 9 The nervous system: spinal cord and spinal nerves
Role of nervous system p188 Maintains homeostasis Chief coordinating agency for all body systems Detects and responds to stimuli (changes in and out of body)
Structural divisions of nervous system p188 Central nervous system (CNS) Peripheral nervous system
Functional divisions of Nervous System p189 – Somatic nervous system – Autonomic nervous system – Sympathetic nervous system – Parasympathetic nervous system
Neuron p189 Dendrite Axon Myelin sheath
Types of Neurons p190 Sensory neurons: afferent neurons Motor neurons: efferent neurons Interneurons
Neuroglia p191 Cells that protect and nourish nerve tissue. Ex: Schwann cells, astrocytes Most tumors of the nervous system involve neuroglial tissue since it can undergo cell division.
Myelin p193 Myelin sheath speeds conduction. The nerve impulses jumps from node to node. This is called saltatory conduction.
The Nerve Impulse (action potential) p192 Analogy: spread of an electric current along a wire. Na+ and K+ enter and leave the cell via diffusion. After the nerve impulse has been transmitted, the ions return to their original places and the neuron is ready to transmit a nerve impulse again.
The synapse p194 Chemical Electrical Neurotransmitters: Norepinephrine (noradrenalin) Acetylcholine Neurotransmitters must be removed from synaptic cleft Reuptake Enzymes diffusion
Electrical synapses p194 Electrical synapses are not chemically controlled. Nerve impulses are transmitted without neurotransmitters. Electrical synapses can be found in smooth muscle, cardiac muscle, and in the CNS.
Spinal cord p195 Link between the peripheral nervous system and the brain Protection Structure Ascending nerve tracts Descending nerve tracts
Dermatomes p201 Sciatica Herpes zoster
The Reflex Arc p 195 Table 9-2 p198.
Medical procedures involving the spinal cord p197 Lumbar puncture Epidural or spinal anesthesia
Diseases/disorders of spinal cord p198 Spinal cord injury – May cause paralysis Monoplegia Paraplegia Hemiplegia Tetraplegia or quadraplegia
Autonomic nervous system p201 2 branches – Sympathetic nervous system – Parasympathetic nervous system
Sympathetic nervous system Noradrenalin (norepinephrine) – Fight or flight Adrenergic, sympathomimetic – Sympathetic receptors Beta1 Beta2 Alpha
Parasympathetic nervous system Acetylcholine – Rest and digest Cholinergic parasympathomimetic – SLUDD Salivation Lacrimation Urination Digestion Defecation Rest and Digest
Autonomic nervous system p201 Table 9-4 page 204