PERF 510- Human Physiology
Ch. 5 and 49 outline
Nervous System Organization
Central NS- the brain and spinal cord, processing and control center
Peripheral NS- cranial nerves and spinal nerves, communication between CNS and rest of body
Afferent (sensory) NS- somatic and visceral nerve fibers, body → CNS
Efferent (motor) NS- motor nerve fibers, CNS → body
Somatic NS- voluntary somatic motor control, skeletal muscles
Autonomic NS- involuntary visceral motor control, cardiac and smooth muscles / glands
Parasympathetic NS- resting activity = “rest and digest”
Sympathetic NS- physical activity = “fight of flight”
Nervous Tissue Histology
Neuroglial cells = types of support cells found within nervous tissue, non-conductive
Astrocytes- star shaped, support neurons and other neuroglial cells
Secrete neurotransmitters and are involved in synapse function
Play a role in re-myelination of damaged neurons and immune response within the CNS
Gray matter = protoplasmic astrocytes and unmyelinated gray neurons
White matter = fibrous astrocytes and myelinated white neurons
Microglial Cells- phagocytic immune cells within CNS
May also play a role in protection from Tau and Amyloid proteins
Ependymal Cells- ciliated cells which line the central canal of spinal cord and ventricles of the brain
Secrete and circulate cerebrospinal fluid
Satellite Cells- flat cells which surround the cell body (soma) of neurons within PNS ganglia
Oligodendrocytes- form myelin sheath around CNS neurons
Schwann Cells- form myelin sheath around PNS neurons
Myelin is a fatty insulator which allows action
potentials to travel faster in myelinated neurons
Nodes of Ranier- small gaps in the myelin where
membrane depolarization and repolarization (an
action potential) occurs
Saltatory conduction- action potentials skips over
myelin, occurring only within Nodes of Ranier
, Neurons- specialized cells which rapidly conduct action potentials and release neurotransmitters
Unipolar- soma has a single extension which branches into an axon and a single dendrite
Bipolar- soma has 2 extensions, 1 forming an axon and 1 forming a single dendrite
Multipolar- soma has multiple extensions forming dendrites and an extension forming an axon
Parts of a typical multipolar neuron
Dendrites- short thin branches, terminal end = dendritic knob
Contain receptors for neurotransmitters = signal in
Receptors are associated with ligand gated sodium (Na) channels
Soma or Cell Body- typical, highly specialized eukaryotic cells
Nissel Bodies- vast endoplasmic reticulum needed for producing neurotransmitter molecules
Extensive Golgi Apparatus allows processing and packaging w/in vesicles (neurotransmitters)
Ligand gated Na channels → may also act as signal in
Axon Hillock- tapered end of soma which leads to the axon
Small number of ligand gated channels (serves as signal in, but less sensitive than dendrites/soma)
Axon- long cellular extension which allows rapid propagation of an action potential
Large number of voltage gated sodium and potassium channels
May be myelinated (white) or unmyelinated (gray)
Telondendria- thin, hairlike branches of the axon which lead to telondendria end bulbs (terminal boutons or
telondendria axon terminals)
These form a synapse, a small space between the telondedria and another neuron or effector cell
Vesicles w/in telondendria respond to arriving action potentials by fusing to the plasma membrane
These vesicles store neurotransmitters, which are released into the synaptic cleft
Diffusion across the cleft allows them to attach to receptors on post-synaptic membranes
Effects may be excitatory, inhibitory or both
Types of specialized neurons
Autorhythmic neurons- membranes contain Na leak channels which allow Na influx at a given rate. When
enough Na has entered the cell (threshold), an action potential will occur without outside stimulus
Summation neurons- accumulation of neurotransmitters within the synapse causes post-synaptic neuron to
undergo rapid action potentials
Temporal- the same presynaptic neurons undergoes multiple action potentials
Spatial- multiple pre-synaptic neurons converge on same synapse and each contribute
Ch. 5 and 49 outline
Nervous System Organization
Central NS- the brain and spinal cord, processing and control center
Peripheral NS- cranial nerves and spinal nerves, communication between CNS and rest of body
Afferent (sensory) NS- somatic and visceral nerve fibers, body → CNS
Efferent (motor) NS- motor nerve fibers, CNS → body
Somatic NS- voluntary somatic motor control, skeletal muscles
Autonomic NS- involuntary visceral motor control, cardiac and smooth muscles / glands
Parasympathetic NS- resting activity = “rest and digest”
Sympathetic NS- physical activity = “fight of flight”
Nervous Tissue Histology
Neuroglial cells = types of support cells found within nervous tissue, non-conductive
Astrocytes- star shaped, support neurons and other neuroglial cells
Secrete neurotransmitters and are involved in synapse function
Play a role in re-myelination of damaged neurons and immune response within the CNS
Gray matter = protoplasmic astrocytes and unmyelinated gray neurons
White matter = fibrous astrocytes and myelinated white neurons
Microglial Cells- phagocytic immune cells within CNS
May also play a role in protection from Tau and Amyloid proteins
Ependymal Cells- ciliated cells which line the central canal of spinal cord and ventricles of the brain
Secrete and circulate cerebrospinal fluid
Satellite Cells- flat cells which surround the cell body (soma) of neurons within PNS ganglia
Oligodendrocytes- form myelin sheath around CNS neurons
Schwann Cells- form myelin sheath around PNS neurons
Myelin is a fatty insulator which allows action
potentials to travel faster in myelinated neurons
Nodes of Ranier- small gaps in the myelin where
membrane depolarization and repolarization (an
action potential) occurs
Saltatory conduction- action potentials skips over
myelin, occurring only within Nodes of Ranier
, Neurons- specialized cells which rapidly conduct action potentials and release neurotransmitters
Unipolar- soma has a single extension which branches into an axon and a single dendrite
Bipolar- soma has 2 extensions, 1 forming an axon and 1 forming a single dendrite
Multipolar- soma has multiple extensions forming dendrites and an extension forming an axon
Parts of a typical multipolar neuron
Dendrites- short thin branches, terminal end = dendritic knob
Contain receptors for neurotransmitters = signal in
Receptors are associated with ligand gated sodium (Na) channels
Soma or Cell Body- typical, highly specialized eukaryotic cells
Nissel Bodies- vast endoplasmic reticulum needed for producing neurotransmitter molecules
Extensive Golgi Apparatus allows processing and packaging w/in vesicles (neurotransmitters)
Ligand gated Na channels → may also act as signal in
Axon Hillock- tapered end of soma which leads to the axon
Small number of ligand gated channels (serves as signal in, but less sensitive than dendrites/soma)
Axon- long cellular extension which allows rapid propagation of an action potential
Large number of voltage gated sodium and potassium channels
May be myelinated (white) or unmyelinated (gray)
Telondendria- thin, hairlike branches of the axon which lead to telondendria end bulbs (terminal boutons or
telondendria axon terminals)
These form a synapse, a small space between the telondedria and another neuron or effector cell
Vesicles w/in telondendria respond to arriving action potentials by fusing to the plasma membrane
These vesicles store neurotransmitters, which are released into the synaptic cleft
Diffusion across the cleft allows them to attach to receptors on post-synaptic membranes
Effects may be excitatory, inhibitory or both
Types of specialized neurons
Autorhythmic neurons- membranes contain Na leak channels which allow Na influx at a given rate. When
enough Na has entered the cell (threshold), an action potential will occur without outside stimulus
Summation neurons- accumulation of neurotransmitters within the synapse causes post-synaptic neuron to
undergo rapid action potentials
Temporal- the same presynaptic neurons undergoes multiple action potentials
Spatial- multiple pre-synaptic neurons converge on same synapse and each contribute
