0-1 chapter 12 Nervous Tissue Flashcards Preview

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Flashcards in 0-1 chapter 12 Nervous Tissue Deck (174)
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1

Overview of Nervous System

endocrine and nervous system maintain internal coordination

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endocrine system

communicates by means of chemical messengers (hormones) secreted into to the blood

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nervous system

employs electrical and chemical means to send messages from cell to cell

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nervous system carries out its task in three basic steps

-receive information and transmits coded messages
• processes this information
• issue commands

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-receive information and transmits coded messages

•sense organs receive information about changes in the body and the external environment, and transmits coded messages to the spinal cord and the brain

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• processes this information

•brain and spinal cord processes this information, relates it to past experiences, and determine what response is appropriate to the circumstances

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• issue commands

brain and spinal cord issue commands to muscles and gland cells to carry out such a response

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Two Major Anatomical Subdivisions of Nervous System

central nervous system (CNS)
peripheral nervous system (PNS)

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central nervous system (CNS)

central nervous system (CNS)
–brain and spinal cord enclosed in bony coverings
•enclosed by cranium and vertebral column

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peripheral nervous system (PNS)

–all the nervous system except the brain and spinal cord
–composed of nerves and ganglia

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nerve

a bundle of nerve fibers (axons) wrapped in fibrous connective tissue

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ganglion

a knot-like swelling in a nerve where neuron cell bodies are concentrated

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Sensory Divisions of PNS

sensory (afferent) division
motor (efferent) division

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sensory (afferent) division

carries sensory signals from various receptors to the CNS
–informs the CNS of stimuli within or around the body
–somatic sensory division –
–visceral sensory division

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somatic sensory division

carries signals from receptors in the skin, muscles, bones, and joints

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visceral sensory division

carries signals from the viscera of the thoracic and abdominal cavities
•heart, lungs, stomach, and urinary bladder

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motor (efferent) division

carries signals from the CNS to gland and muscle cells that carry out the body‟s response
-somatic motor division
-visceral motor division (autonomic nervous system)

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somatic motor division

carries signals to skeletal muscles
•output produces muscular contraction as well as somatic reflexes –involuntary muscle contractions

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visceral motor division (autonomic nervous system)

carries signals to glands, cardiac muscle, and smooth muscle
-sympathetic division
-parasympathetic division

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sympathetic division

–tends to arouse body for action
–accelerating heart beat and respiration, while inhibiting digestive and urinary systems

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parasympathetic division

–tends to have calming effect
–slows heart rate and breathing
–stimulates digestive and urinary systems

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effectors

cells and organs that respond to commands from the CNS

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Universal Properties of Neurons

excitability(irritability)
conductivity
secretion

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secretion

when electrical signal reaches end of nerve fiber, a chemical neurotransmitter is secreted that crosses the gap and stimulates the next cell

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Functional Types of Neurons

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sensory (afferent) neurons
interneurons(association) neurons
motor (efferent)neuron

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sensory (afferent) neurons

–specialized to detect stimuli
–transmit information about them to the CNS
•begin in almost every organ in the body and end in CNS
•afferent–conducting signals toward CNS

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afferent

conducting signals toward CNS

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interneurons(association) neurons

–lie entirely within the CNS
–receive signals from many neurons and carry out the integrative function
•process, store, and retrieve information and „make decisions‟ that determine how the body will respond to stimuli
–90% of all neurons are interneurons
–lie between, and interconnect the incoming sensory pathways, and the outgoing motor pathways of the CNS

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motor (efferent)neuron

–send signals out to muscles and gland cells (the effectors)
•motor because most of them lead to muscles
•efferent neurons conduct signals away from the CNS

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efferent

neurons conduct signals away from the CNS