11-1. Nerve Tissue Flashcards
What are the functions of nerve?
- sensory (detect changes inside and outside body)
- integrative (interpret changes and decide how to respond)
- motor (respond to interpretation by muscle contraction or gland secretion)
- homeostasis (by sensing and responding to changes in environment, the NS allows the body to make the adjustments needed to keep a fairly constant internal environment)
What are the two possible responses to a nerve impulse?
muscle contraction or gland secretion
central nervous system
control center for the whole system
What organs does the CNS consist of?
brain and spinal cord
All sensations must be relayed through the ___ to be felt and acted upon.
CNS
peripheral nervous system
all nerves outside the CNS that connect the brain and spinal cord to the rest of the body
What organs does the PNS consist of?
all nerves outside CNS
What are the two divisions of the PNS?
afferent division (input) and efferent division (output)
afferent division of PNS
input - sensory neurons carrying information from receptors into the CNS
efferent division of PNS
output - motor neurons that carry information from the CNS out to the muscles or glands that respond
What are the two branches of the efferent division of the PNS?
somatic (voluntary) and autonomic (involuntary)
somatic nervous system
efferent nerves carrying impulses from CNS to skeletal muscles - controls voluntary movements
autonomic nervous system
efferent nerves carrying impulses from CNS to cardiac muscle, smooth muscle, or glands (“internal organs) - involuntary movements
What are the two divisions of the autonomic nervous system?
parasympathetic and sympathetic
parasympathetic nervous system
“rest and repose” - conserves energy in non-stress situations (normally in control)
sympathetic nervous system
“fight or flight” - mobilizes body systems during stress
Cardiac Nerve (SANS)
increases heart rate
Vagus Nerve (PANS)
slows down heart rate
Which system controls voluntary movements?
somatic
Which system controls involuntary movements?
autonomic
Which system contains sensory neurons?
afferent
Which system contains efferent neurons?
efferent
neuroglia
“nerve glue” - supporting cells of the nervous system. Smaller than neurons but outnumber them 9 to 1 - make up about half the mass of the brain
What types of neuroglia are found in the CNS?
astrocytes, oligodendrocytes, microglia, ependyma
What types of neuroglia are found in the PNS?
Schwann and satellite cells
What are the functions of neuroglia?
Do NOT send nerve impulses:
- form a supporting network around neurons; give shape to brain
- some help nourish neurons by attaching them to capillaries
- certain types produce a fatty, white covering around nerve fibers which increase the speed of nerve impulse conduction (myelin sheath)
- Some protect CNS from disease by engulfing bacteria and viruses
neurons
structural unit of the nervous system, these cells conduct nerve impulses from one part of the body to another
What are the characteristics of neurons?
- extreme longevity (with good nutrition, they can function for over 100 years)
- amitotic (unable to divide)
- high metabolic rate (need a constant supply of O2 and glucose - can’t survive for more than a few mins without O2)
cell body
enlarged end containing nucleus and most of the cytoplasm
dendrites
highly branched extensions of cell body; pick up incoming signals like antennae
axon
single long thin process that carries nerve impulse away from cell body
telodendria
many fine branches at end of axon
synaptic knobs
swollen tips at end of telodendria, also called axon terminals
