NERVOUS SYSTEM REVIEW

Be able to explain the 3 necessary functions of the nervous system

Identify the components of the CNS and the PNS 2 big initial divisions: Central Nervous System CNS The brain + the spinal cord The center of integration and control Peripheral Nervous System PNS The nervous system outside of the brain and spinal cord Consists of: 31 Spinal nerves Carry info to and from the spinal cord 12 Cranial nerves Carry info to and from the brain

Distinguish between the sensory (afferent) and motor (efferent) divisions Can be divided into: 1. Sensory Division Afferent division Conducts impulses from receptors to the CNS Informs the CNS of the state of the body interior and exterior Sensory nerve fibers can be somatic (from skin, skeletal muscles or joints) or visceral (from organs w/i the ventral body cavity) 2. Motor Division Efferent division Conducts impulses from CNS to effectors (muscles/glands) Motor nerve fibers

Somatic nervous system and the autonomic (ANS) nervous system Somatic- conscious, voluntary control of skeletal muscles ANS- automatic, involuntary

Sympathetic / Parasympathetic nervous system These 2 systems are antagonistic. Typically, we balance these 2 to keep ourselves in a state of dynamic balance.

Functional differences of supporting cells and neurons Supporting cells (Neuroglia) insulate/protect neuron; do not transmit nor do they lose ability to divide Neurons transmit messages impulse

Types of supporting cells

Supporting cells Astrocytes – control the chemical environment of the brain; BBB Are star-shaped Microglia – dispose of debris, dead cells Are spider-shaped

Supporting cells Oligodendrocytes – create the myelin sheath only in the CNS Ependymal cells – are ciliated to spread cerebrospinal fluid (CSF)

Axons and dendrites

Axons and dendrites Dendrites – conduct impulses toward the cell body Axons – conduct impulses away from the cell body

Synapse/Synaptic cleft/synaptic membrane (pre and post) Synapse – where neurons meet Synaptic Cleft - space between neurons Synaptic Membrane – pre is for sending neurotransmitters, post is for receiving neurotransmitters for an AP

Myelin and relationship to Schwann cells Myelin insulates axon to speed up rate of transmission; Schwann is only in PNS

Cutaneous sense organs and proprioceptors Cutaneous sense organs (CSO) – are found in skin and have sensory receptors; Proprioceptors – sensory receptors in muscles and tendons to detect stretch and tension

Association or interneurons Between; connect sensory to motor neurons

Polarization/Depolarization/ and Repolarization Polarization – at rest, Na out/K in Depolariozation – Na rush in to generate an action potential (AP) Repolarization – returns to rest and has a refractory period

Irritability and conductivity of neurons Irritability – ability to respond to a stimulus and disrupt the threshold to produce an AP Conductivity – ability to transmit and spread an AP

Electrochemical nerve impulse Is positive charge and is sent along axon to terminal then becomes chemical as neurotransmitters get released to produce another AP

Elements of a reflex arc ALL REFLEX ARCS HAVE A MINIMUM OF 5 ELEMENTS: 1. A sensory receptor (which reacts to a stimulus) 2. An effector organ (muscle or gland to be stimulated) 3 and 4. Afferent and Efferent neurons to connect the two (interneuron or association) 5. CNS integration center

Autonomic and Somatic Reflexes Autonomic – regulates smooth muscles, heart and glands Somatic regulates activity of skeletal muscles Both are still reflexes, automatic, involuntary responses

The Brain diagram