Test 3- Nervous Tissue/Nervous System Overview Flashcards
What are the two control systems of the body?
Endocrine
Nervous System
Glands communicate with, integrate and control organs by secreting hormones into the blood
Endocrine system
Involves a slow response to stimuli, but lasts a long time
Endocrine System
Brain, spinal cord, and nerves communicate, integrate, and control body functions with nerve impulses/action potentials
Nervous System
Involves a fast response to stimuli but lasts a short time
Nervous System
Two major divisions of the NS
Central Nervous System
Peripheral Nervous System
Brain and spinal cord
CNS
Control and integration
CNS
Nerve tissue outside the CNS
PNS
Used for communication and connects CNS to receptors, glands, ect.
PNS
What are the 3 functions of the Nervous System
Allows sensory input (PNS)
Performs integration (CNS)
Stimulates motor output
Organs, glands, or muscles that respond to a stimulus
Effectors
Effectors of the skeletal muscles
Somatic effectors
Effectors of the glands, smooth muscle in organs and cardiac muscles
Visceral effectors
Two types of cells in the NS
Neurons
Neuroglia cells
Carries nerve impulses
neurons
Cells that do not divide and live and function for a lifetime
Neurons
Cells that support, protect and nourish neurons
Neuroglial cells
Make up a majority of nerve cell tissue
Neuroglial cells
Types of neuroglial cells
Schwann cells Oligodendrocytes Astrocytes Microglia Ependymal cells
Form a regeneration tube that eventually becomes functional
Schwann cells
PNS myelin
Schwann cells
CNS myelin
Oligodendrocytes
Forms the blood-brain barrier
Astrocytes
Why is there a blood-brain barrier?
Prevents potentially toxic substances from entering the CNS
Phagocytosis to prevent infection
Microglia
Cerebrospinal fluid circulation
Ependymal cells
What are neurons made of?
Cell body
Dendrites
Axon
Contains nucleus and other organelles
Cell body
Branched extensions of the cell body
Dendrites
Carry impulses toward the cell body
Dendrites
Long extensions of cell body, ending in synaptic/axon terminal with synaptic knobs
Axon
Carries impulses away from the cell body
Axon
Axons of thick, rapidly conducting neurons are covered with a white fatty myelin sheath for protection/prevention of signal loss
Myelinated neurons
Increases the speed of impulse conduction and makes the process more energy efficient
myelinated neurons
In the PNS, myelin sheath is made of ____ cells called ____ cells wrapping around the axon
neuroglial, Schwann
In the CNS, the sheath is made of _____ cells called ______ wrapping around the axon
neuroglial, oligodendrocytes
Gaps in between either schwann cells or oligodendrocytes
Nodes of Ranvier
Where neuron cell bodies are clustered
Gray matter
The outermost layer of gray matter in the brain
Cerebral/Cerebellar Cortex
Consists mainly of axons and neuroglia
White matter
Usually superficial to gray matter in the CBS other than the cerebral cortex
White matter
What causes the white color in white matter?
Myelin sheaths surrounding many of the axons
3 types of neurons by structure
Multipolar
Bipolar
Unipolar
Have more than 2 processes extending from cell body (most neurons)
Multipolar
Have 2 processes that extend from opposite sides of the cell bod
Bipolar
Short single process
Unipolar
3 types of neuron by function
sensory (afferent) neurons
motor (efferent) neurons
interneurons
Carry impulses from receptors in the PNS to the CNS
Sensory (afferent) neurons
Carry impulses from the CNS to the muscles and glands
Motor (efferent) neurons
Carry impulses within the CNS and relay impulses from the sensory neurons to the motor neurons
Interneurons
Communication junction between a neuron and either another neuron (postsynaptic neuron) or a muscle
Synapse
Space between the axon and dendrite
Synaptic cleft
At the ends of synaptic terminals and contain neurotransmitters
Synaptic knobs
Stimulates muscle fibers
Acetylcholine (ACh)
Activates “fight or flight”
Norepinephrine (NE)
Regulates mood and behavior
Serotonin
Involved in motor control and emotions
Dopamine
One cell is acted on by many cells
Convergence of input
One cell influences many cells
Divergency of output
What does a postsynaptic neuron fire depend on?
- number of active synapses
2. whether the synapses are excitatory or inhibitory
Effects of many neurotransmitters are added together
summation
One single presynaptic increases frequency of activity to affect post-synaptic membrane
Temporal summation
More than one presynaptic active simultaneously
Spatial summation
CT covering of each axon/Schwann cells surrounding axon
Endoneurium
Bundles of axons
Fascicles
CT surrounding each fascicle
Perineurium
CT surrounding the entire nerve
Epineurium
Nerves containing bundles of sensory neuron fibers only
sensory nerves
Nerves containing bundles of motor neuron fibers only
Motor nerves
Nerves containing bundles of both sensory and motor neuron fibers
Mixed nerves
A nerve in the CNS
Tract
Reflex arc
Sensory receptor Sensory neuron Interneuron Motor neuron Effector
Autoimmune disease that progressively destroys the myelin sheaths of neurons in the brain and spinal cord
Multiple sclerosis