Nervous Tissue Flashcards
The nervous system receives stimuli from the body and environment via
Sensory receptors
Neurons transmit
Stimulus to muscles, glands, and other neurons via synapses
Neurons are supported by
Neuroglial cells
The Na-K pump maintains
A negative potential inside the neuron’s plasma membrane
Two main parts of the nervous system are
-Central Nervous System (CNS)
-Peripheral Nervous System (PNS)
The CNS includes
-brain
-spinal cord
All nervous tissue outside of the CNS is part of the
Peripheral nervous system
The PNS is subdivided into
-Afferent Sensory Pathways (towards the CNS)
-Efferent Motor Pathways (away from CNS)
Afferent division of the PNS can be divided into
-somatic sensory receptors
-visceral sensory receptors
The Efferent division of the PNS can be further divided into
-Somatic Nervous System to skeletal muscle
-Autonomic Nervous System to viscera
The Autonomic Nervous System of the Efferent PNS can be further divided into
-sympathetic (fight or flight)
-parasympathetic (rest and digest)
Somatic Afferent division of the PNS (3)
-sensory
-TO the CNS from skeletal muscle and skin
-pressure and pain receptors
Visceral Afferent division of the PNS (2)
-sensory
-TO CNS from the heart, GI tract, urinary and reproductive systems
Somatic Efferent division of the PNS (2)
-motor
-FROM the CNS to skeletal muscle
Both the sympathetic and parasympathetic (3)
-part of autonomic nervous system of PNS
-motor
-FROM the CNS to cistern and secretory cells
All neurons contain (3)
-Soma (cell body)
-one axon
-one or more dendrites
The cell body of neurons (4)
-large, round, centrally placed nucleus
-prominent nucleolus
-most located in the CNS
-sensory and terminal effector neuron cell bodies located in peripheral ganglia
Dendrites (7)
-processes which extend from the neuron’s cell body
-may have one or many
-irregular in shape
-branch
-form synapses (connections) with other axons
-conduct nerve impulses unidirectionally
-studded with dendritic spines (gemmules)
The site of a neuron synapse is
The dendritic spine (gemmule)
Neurons can be classified as (3)
-multipolar
-bipolar
-unipolar (pseudo-unipolar)
The axon / nerve fibre (4)
-single, long cytoplasmic process
-nerve impulse travels along axon and away from cell body
-may be insulated in a myelin sheath
-terminate at fine branches called Telodendrons that end at their Synaptic Terminal
The Axolemma is the
Plasma membrane (plasmalemma) of the axon
Multipolar Neurons (4)
-one axon
-many dendrites
-common
-motor neurons
Bipolar Neurons (4)
-one axon
-one dendrite
-rare
-receptors for smell, sight, and balance
Unipolar (pseudo-unipolar) Neurons (4)
-one axon arising from a stem from the cell body
-several dendrites
-common
-sensory neurons
Neuroglia are ____ and found within
-support cells
-CNS and PNS
Four types of Neuroglia found in the CNS
-Astrocytes
-Oligodendrocytes
-Microglia
-Ependymal Cells
Two types of Neuroglia found in the PNS
-Schwann Cells
-Satellite Cells
Astrocytes, oligodendrocytes, microfilaments, and ependymal cells are
Neuroglia of the CNS
Schwann and Satellite cells are
Neuroglia of the PNS
Astrocytes (5)
-Neuroglia of the CNS
-star shaped with branching processes
-pale nuclei
-metabolic exchange between neurons and blood
-structural support to neurons
Oligodendrocytes (5)
-Neuroglia of the CNS
-Schwann cells in PNS
-dense nuclei
-congregate around cell bodies
-produce myelin around axons in the CNS
Ependymal Cells (4)
-Neuroglia of the CNS
-cuboidal - columnar epithelial cells
-line fluid-filled vacuities of the brain (ventricles) and spinal cord (cerebral spinal fluid)
-may have cilia or microvilli for absorption
Microglia (4)
-Neuroglia of CNS
-small, few in numbers
-difficult to see with microscope
-develop into large, amoeboid phagocytes in response to tissue damage
Schwann Cells (4)
-Neuroglia of PNS
-oligodendrocytes in CNS
-surround axons
-produce myelin (cell membrane)
Satellite Cells (3)
-Neuroglia of PNS
-surround cell bodies within ganglia
-provide physical and metabolic support
In the PNS, all axons are enveloped by ____ which forms ___
Schwann Cells; Myelin
Unmyelinated nerves are
Grey matter
Myelinated nerves are
White matter (cranial and spinal nerves)
Myelin (4)
-fatty substance
-white
-modified plasma membrane
-reduced protein, high lipid content
Internode
Segment of Myelin produced by each Schwann cell
Node of Ranvier (2)
-between each internode
-Schwann cells encase the axon but DO NOT form a myelin sheath
Myelination provides ___ which ___
Insulation; inhibits diffusion of nerve impulses
Saltatory conduction
Nerve impulses spread along the axon by jumping from one node of Ranvier to the next, allowing for rapid conduction of nerve impulses
The brain and spinal cord contain both
White and grey matter
Grey matter is made of (4)
-neuron cell bodies
-axons (mostly unmyelinated)
-neuroglia
-blood vessels
White matter is made of (3)
-axons (mostly myelinated)
-neuroglia
-blood vessels
In the brain, grey matter is the ___ while white matter is the ___
Outer layer; Inner layer
In the spinal cord, grey matter is the ___ while white matter is the ___
Inner Layer; Outer Layer
Meninges are ___ and include ____
-the three layers of connective tissue surrounding the brain and spinal cord
-Dura Mater, Arachnoid Membrane, Pia Mater
Dura mater (2)
-outer layer of meninges
-tough, fibroelastic regular dense connective tissue
Arachnoid Membrane (3)
-middle layer of meninges
-fine, cobweb like
-spaces filled with cerebral spinal fluid (CSF)
Pia Mater (3)
-inner layer of meninges
-very fine reticular and collagen fibres
-blood vessels
The Dura mater, Arachnoid membrane, and Pia mater are collectively called the
Meninges
Nerve fibres (4)
-the axon of the neuron
-can be afferent (to CNS) or efferent (away from CNS)
-can be myelinated or unmyelinted
-enclosed by reticular fibres (endoneurium)
The endoneurium surrounds
Each axon
A collection of fibres (axons) is called
Fasciculus
The fasciculus is surrounded by
Connective tissue (perineurium)
A collection of fasciculi is called
A nerve
The perineurium surrounds
Each fasciculus
Nerves contain (2)
-both afferent and efferent fibres
-blood vessels
The nerve is bound by
Connective tissue (Epineurium)
Ganglia (2)
-clusters of neuron cell bodies outside of the CNS
-surrounded by connective tissues continuous with the epineurium
Two types of Ganglia and 3 facts for each
Craniospinal Ganglia
-close to brain and spinal cord
-afferent (sensory) fibres
-unipolar neurons
Autonomic Ganglia
-can be free structures or within tissues
-Efferent (motor) fibres
-Multipolar neurons
Nerve impulses cross from one neuron to another at the
Synapse
Passage of stimulus across the synapse can be via (2)
-chemical transmitters
-direct electrical transmission
Synapses can be (2)
-excitatory
-inhibitory
Most synapses are ___, but (less commonly) can also be ____ and ___
-axo-dendritic
-axo-somatic and axo-axonic
Five common neurotransmitters include:
-acetylcholine
-epinephrine (adrenaline)
-norepinephrine (noradrenaline)
-serotonin
-gamma amino butyric acid (GABA)
Chemical transmissions at the synapse (2)
-neurotransmitters are produced by the pre-synaptic neuron
-synaptic cleft separates pre- and post-synaptic neurons were the neurotransmitters cross
The cytoplasm of pre-synaptic neurons contains (2)
-mitochondria
-vesicles of neurotransmitters
Electrical Transmission at the Synapse (3)
-nerve impulses are transmitted electrically WITHOUT a neurotransmitter
-rapid spread of signal (ions)
-no synaptic cleft (pre- and post-synaptic membranes are in close apposition via gap junctions)
Motor End Plates / Neuromuscular Junctions (5)
-specialized synaptic nerve endings
-general somatic efferent (motor) nerves
-skeletal muscle
-pre-synaptic neuron has synaptic vesicles (signalling via neurotransmitters)
-post-synaptic membrane (on the skeletal muscle) is specialized with deep folds (Secondary Synaptic Clefts)
Specialized synaptic nerve endings found in skeletal muscle are called
Motor End Plates / Neuromuscular Junctions
True or False: Dendrites can be myelinated
False. Only the axon can be myelinated
Sensory Receptors (2)
-can be nerve endings (ie. dendrites) OR specialized cells
-convert stimulus into afferent nerve signals (ie. go TO the CNS)
Three types of Sensory Receptors
-free nerve endings (small terminal dendrite branches lacking Schwann cells)
-encapsulated endings (terminal branches of the neuron surrounded by a capsule)
-lamellated endings (layers of connective tissue cells)
Which sensory receptor is used for pressure
Lamellated Endings
Which sensory receptor is used for temperature, touch, and pain
Free Nerve Endings
Which sensory receptor is used to modify/amplify stimulus and maintain ionic environment?
Encapsulated Endings
Nerves exit from the spinal cord as
Spinal Nerves containing both afferent and efferent fibres
Dorsal Root is
Afferent (sensory)
The dorsal and ventral root come together to form the
Spinal nerve
Ventral Root
Efferent (motor)
The dorsal root contains sensory nerves of the (2)
-general somatic afferent (from body)
-general visceral afferent (from viscera)
Cell bodies of the dorsal root are (2)
-lodged in dorsal root ganglion near the spinal cord
-unipolar (pseudo-unipolar) neurons
Ventral root contains motor nerves of
-general somatic efferent (to skeletal muscle)
-autonomic nervous system (to viscera)
General somatic efferent axons terminate on
Skeletal muscle as motor end plates
The cell bodies of Ventral root are
Lodged in grey matter of the spinal cord
Autonomic nervous system axons synapse with
A second neuron in an autonomic ganglion within the tissue
Two types of neurons in the brain
-Purkinje Cells
-Granule Cells
Two functional types of neurons
-pyramidal motor neurons
-sensory neurons
Purkinje Cells (4)
-found in cerebellum
-large, flask shaped
-multipolar
-have elaborate dendritic tree
Granule Cells (4)
-found in the cerebellum
-very small
-one axon that divides to make contact with Purkinje dendrites
-several dendrites
Pyramidal Motor Neurons (6)
-general somatic efferent neurons
-ventral horn of spinal cord
-multipolar
-cell body is pyramidal shaped
-dendrites receive synapses from sensory neurons
-axon terminates on skeletal muscle as a motor end plate
Sensory neurons (6)
-general somatic afferent neurons
-dorsal root ganglia or cranial nerve ganglia
-unipolar (pseudo-unipolar) neurons
-cell body is round
-dendrites form sensory endings
-axon enters CNS
Two types of specialized cells of the nervous system
-Neurosensory Cells
-Neurosecretory cells
Neurosensory cells (3)
-located in special sense organs
-can be true neurons (rods and cons in retina, olfactory cells)
-can be adapted to transmit stimuli (taste buds, hair cells of inner ear)
What specialized nervous system cell releases hormones rather than neurotransmitters
Neurosecretory Cells
Neurosecretory cells (2)
-secrete hormones rather than neurotransmitters
-found in hypothalamus and adrenal medulla
