Functions of the Nervous System
-Receive Sensory Input
-Control muscles and glands
-Establish and Maintain Mental Activity
Sensory (afferent) Division of PNS
Conducts action potentials from sensory receptors to the CNS
The neurons that transmit action potentials to the CNS
Motor (efferent) Division of PNS
Conducts action potentials from the CNS to effector organs, such as muscles and glands.
The neurons that transmit action potentials from the CNS toward the periphery
Somatic Nervous System
Transmits actions potentials from the CNS to the skeletal muscles
Autonomic Nervous System
Transmits action potentials from the CNS to cardiac muscle and smooth muscle glands
Receives stimulus, conducts action potential, and transmits signals to other neurons or effector cells
Receive information from other neurons or from sensory receptors and transmit the information toward the neuron cell body
A long cell extending from the neuron cell body. Highly unbranched. Takes information away from neuron cell body to skeletal muscles.
Have many dendrites and a single axon. Common in CNS, and motor neurons
Have two processes: one dendrite and one axon. Located in some sensory neurons.
Have a single process extending from cell body. One extends into the periphery and the other into CNS. Axon receives sensory info at the periphery and transmits that info in the form of action potentials to the CNS.
Non-neuronal cells of CNS and PNS. Support Neurons.
And in the PNS: Schwann Cells
Serve as major supporting tissue in CNS. Maintain the brain-blood barrier. Help limit damage to neural tissue and control interstitial environment
-Secrete and monitor cerebrospinal fluid; Circulate fluid with cilia
-Line fluid filled cavities within the CNS
Act as immune cells of the CNS. Help protect the brain by removing bacteria and cell debris
Oligodendrocytes in CNS And
Schwann Cells in PNS
Hold nerve fibers together; produce fatty myelin sheath
Rest in the indentations of the oligodendrocytes in the CNS and the Schwann cells in the PNS.
Have myelin sheaths wrapped around them.
Consists of groups of neuron cell bodies and their dendrites, where there is very little myelin. In the CNS, gray matter on the surface of the brain is called the cortex and clusters of gray matter located deeper within the brain are called nuclei
Cluster of neuron cell bodies in PNS
Consist of bundles of parallel axons with their myelin sheath.
Of CNS: Forms nerve tracts, of conductive pathways, which propagate action potentials from one area of CNS to another
Of PNS: Nerves
Resting Membrane Potential is generated by 3 factors
1) A higher concentration of K+ immediately inside the cell membrane
2) A higher concentration of Na+ immediately outside the cell membrane
3) Greater permeability of the cell membrane K+ than to Na+
-Na+ outside membrane
-K+ inside membrans
-Na+ move inside
-K+ move outside membrane
-Restore + outside and - inside
Muscle and Nerve cells are...
excitable cells, meaning that the RMP changes in response to stimuli that activate gated ion channels.
Action potentials jump from one node of Ranvier to the next along the length of the myelinated axon. Greatly increases the conduction velocity
A junction where the axon of one neuron interacts with another neuron or an effector organ
End of the axon
The membrane of the dendrite or effector cell
Space separating the presynaptic and postsynaptic membranes
What happens in the postsynaptic cell if . . .
-If Na+ channels open, the postsynaptic cell becomes depolarized and an action potential will result if threshold is reached.
-If K+ or Cl- channels open, the inside of the postsynaptic cell tends to become more negative (hyperpolarized), and an action potential is inhibited from occurring.
a neurotransmitter that enables learning and memory and also triggers muscle contraction (Excitatory or Inhibitory)
-Myasthenia Gravis results from a reduction in Ach receptors
a precursor of epinephrine that is secreted by the adrenal medulla and also released at synapses (Excitatory)
a neurotransmitter involved in e.g. sleep and depression and memory (Inhibitory)
neurotransmitter that influences voluntary movement, attention, alertness; lack of dopamine linked with Parkinson's disease; (Excitatory and Inhibitory)
an automatic instinctive unlearned reaction to a stimulus
the neural path of a reflex. Basic functional unit of the nervous system bc it is the smallest simplest way of receiving response
Five Basic Components of Reflex Arc
1) A Sensory Receptor
2) A Sensory Neuron
4) Motor neurons
5) An effector organ
Two or more neurons synapse with the same neuron
The axon from one neuron diverged and synapses with more than one other neuron
Connects the spinal cord to the remainder of the brain
Consists of the Medula oblongata, pons, and midbrain
regulates heart rhythm, blood flow, breathing rate, digestion, and vomiting
a band of nerve fibers linking the medulla oblongata and the cerebellum with the midbrain
-Respiratory Center, swallowing,chewing, salivation
-Smallest region of brainstem
-Eye movement, pupil size, lens shape
-Inferior colliculi-Major relay centers for the auditory and nerve pathways in the CNS
-Superior colliculi-Involved in visual reflexes and receive touch and auditory output
Muscular coordination, balance, muscle tone