PNS: all nerves found outside of the brain + spinal cord
Sensory division: afferent send impulses from the senses to the CNS
sympathetic division: used in emergency situations
Parasympathetic: Reduces the sympathetic response and provides a resting function
Motor division: Efferent send impulses from the CNS to the muscles and glands
Nervous= master control system and works with the endocrine system
Sensory input- detects stimuli inside + outside the body
integration: processing + interpreting informqtion
Response- activation of muscles motor output or glands
Major nerve cells:
Neurons: conducts impulses around the body (10%) Nueroglia: “never glue” supports, insulates, and protects neurons
Neurons have different structs but all have a main cell body with processes extending outward.
The cell body contains a nucleus cytoplasm and organelles
Processes are divided into
dendrites - bring impulses toward the cell body
Axon- sends impulses away from the cell body
End in axon terminals which release neurotransmitters to pass the impulse to the next neuron
Neurons are classified by the number of processes extending from the cell body
Neurons are also classified by their function
Afferent- carry impulses towards the CNS
Efferent- carries impulses away from CNS
interneurons- Connect afferent and efferent
Protection
Axons are wrapped in myelin which is like insulation
To form myelin a Schwann cell (type of neuroglial wraps itself around the axon like a coil
The outer layer of the Schwan cell is called the neurilemma
Myelin helps the nerve impulses travel more quickly
Myelin wrappings are called the myelin sheath
Since the sheath is formed by Schwann cells it has gaps called nodes of rainveir
Nuerogili cells within the CNS:
Astrocytes: support + nuerons to capillaiies
Microglia: provide immune response to the CNS
Ependymal cells: secrete + circulate CSF
Oligodendrocytes: provide myelin insulation to neurons
Within the PNS:
Satlite cels: support + anchor nuerons
Schawn cells: proviide mylien inuslation