201 Flashcards
Central Nervous System (CNS)
consists of the brain and spinal cord
The peripheral nervous system (PNS)
consists of all nervous tissue outside the CNS. Components of the PNS include nerves and sensory receptors.
Nervous system divisions
- Nervous system is dived into CNS and PNS
- CNS receives input for the sensory branch of the PNS, interprets is and then out puts signals to the motor brand of the PNS
PNS divisions
- is divided into Sensory and Motor divisions
- Motor division is dived into somatic and autonomic
- autonomic is dived into sympathetic and parasympathetic
The PNS is divided into a sensory (afferent) division and a motor (efferent) division.
- The sensory division conveys sensory input into the CNS from sensory receptors.
- The motor division conveys motor output from the CNS to effectors (muscles and glands).
The efferent (motor) division of the PNS is further subdivided into a somatic nervous system and an autonomic nervous system.
- somatic nervous system (conveys motor output from the CNS to skeletal muscles only)
- autonomic nervous system (conveys motor output from the CNS to smooth muscle, cardiac muscle, and glands).
The autonomic nervous system in turn is divided into a sympathetic division, parasympathetic division, and enteric plexuses.
The enteric plexuses in the wall of the digestive canal regulate the smooth muscle and glands of the digestive canal
The nervous system helps maintain homeostasis and integrates all body activities.
it does this by sensing changes (sensory function), interpreting them (integrative function), and reacting to them (motor function).
Nervous tissue consists of
neurons (nerve cells) and neuroglia.
Neurons have the property of electrical excitability
and are responsible for most unique functions of the nervous system: sensing, thinking, remembering, controlling muscle activity, and regulating glandular secretions.
Most neurons have three parts.
1-The dendrites are the main receiving or input region
2-The cell body, Integration occurs in the cell body, which includes typical cellular organelles.
3-the Axon, responsible for output which propagates nerve impulses toward another neuron, a muscle fiber, or a gland cell.
Synapses
the site of functional contact between two excitable cells. Axon terminals contain synaptic vesicles filled with neurotransmitter molecules.
slow axonal transport and fast axonal transport
systems for conveying materials to and from the cell body and axon terminals.
On the basis of their structure, neurons are classified as
- multipolar,
- bipolar,
- unipolar or pseudounipolar.
Neurons are functionally classified as
- sensory (afferent) neurons,
- motor (efferent) neurons,
- interneurons
Sensory neurons carry sensory information into the CNS.
Motor neurons carry information out of the CNS to effectors (muscles and glands).
Interneurons
located within the CNS between sensory and motor neurons.
Neuroglia
support, nurture, and protect neurons and maintain the interstitial fluid that bathes them.
Neuroglia in the CNS consist of
- astrocytes
- oligodendrocytes
- microglial cells
- ependymal cells
Neuroglia in the PNS consist of
- Schwann cells
- satellite cells.
Two types of neuroglia produce myelin sheaths:
Oligodendrocytes myelinate axons in the CNS, and Schwann cells myelinate axons in the PNS.
White matter consists of aggregates of myelinated axons
gray matter contains cell bodies, dendrites, and axon terminals of neurons unmyelinated axons, and neuroglia.
In the spinal cord, gray matter forms an H-shaped inner core that is surrounded by white matter.
In the brain, a thin, superficial shell of gray matter covers the cerebral and cerebellar hemispheres
Neurons communicate with one another
- using graded potentials, which are used for short-distance communication only
- nerve impulses, which allow communication over long distances within the body.