Nervous and Endocrine System Flashcards
Central Nervous System
includes spinal cord and brain. In the “center” of the body
Peripheral Nervous System:
includes autonomic and somatic nervous systems
Somatic Nervous System
connects to skeletal muscle
Autonomic Nervous System
connects to
smooth (involuntary) muscles
Autonomic Nervous System is further divided into the…
Sympathetic
Nervous System (usually causes effects associated with emergency situations) and the Parasympathetic
Nervous System (promotes activities associated with a normal state).
SENSORY NEURON:
afferent neuron - takes a message from a sense organ to CNS. has long
dendrite and short axon
MOTOR NEURON:
efferent neuron- takes
message away from CNS to a muscle fiber or gland. Short dendrites, long axon.
INTERNEURON:
association neuron or
connector neuron): completely contained within CNS. Conveys messages between parts of the system. Dendrites, and axons, may be long or short.
Nerve Conduction is…
an ELECTROCHEMICAL CHANGE that moves in one direction along the length of a nerve fiber. It is electrochemical because it involves changes in voltage as well as in the concentrations of certain ions.
Resting Potential
When not conducting impulses, there is a voltage difference across the
membrane of the axon of about -60 mV. The negative charge on the
inside of the axon is due to the presence of large negative ions. There are more sodium ions on the outside of the axon compared to the inside of the axon, and more potassium ions on the inside compared to the outside.
ACTION POTENTIAL:
POTENTIAL: if a nerve is stimulated by electric shock, pH change, or mechanical stimulation, a nerve impulse is generated, and a change in potential can be seen.
RECOVERY PHASE:
between transmissions, K+ ions are returned to the inside of the axon, Na+ to the outside. This is done actively
The speed of nerve impulses is?
quite rapid. due to the structure of the nerves. Specifically, the MYELIN SHEATH of most nerve fibers (this sheath is formed by tightly packed spirals of the cell membrane of Schwann cells) and the interruptions or gaps of the sheath called the NODES OF RANVIER.
Myelinated or non-myelinated neurons transmit info faster?
Myelinated because impulse can “skip” over the sheath where as non-myelinated has to go step by step each time
Synapse:
the region between end of an axon and the cell body or dendrite to which it is attached.
Synaptic Endings:
swollen terminal knobs on the ends of axon terminal branches.
Presynaptic Membrane:
the membrane of the axon synaptic
ending.
Postsynaptic Membrane:
the membrane of the next neuron just beyond the axon’s synaptic membrane.