Nerve Cell A&P Pt.2 Flashcards
What are the 3 parts of the PNS?
- The somatic nervous system (SNS).
- The autonomic nervous system (ANS).
- The enteric nervous system (ENS).
What does the sensory portion of the PNS transmit messages to?
The central nervous system (CNS).
What does the CNS communicate actions to?
PNS motor neurons.
What do somatic motor neuron innervate?
Skeletal muscle.
What do autonomic motor neuron innervate?
Smooth muscle, cardiac muscle, glands.
What do enteric motor neuron innervate?
Smooth muscle, glands, and endocrine cells of the GIT.
What is the purpose of the CNS?
To process sensory information.
*Source of thoughts, emotions, and memories.
What are the 4 anatomical portions of the PNS?
- Cranial nerves and branches.
- Spinal nerves and branches.
- Ganglia.
- Sensory receptors.
How many cranial nerves do we have?
13.
How many spinal nerves do we have?
21.
What is the other name for sensory neurons?
Afferent neurons.
What is the other name for motor neurons?
Efferent neurons.
What do sensory/afferent neurons convey?
Information from somatic receptors in the head, body wall, limbs, and receptors for vision, hearing, taste, and smell to CNS.
What is the function of motor neurons?
To conduct impulses from the CNS to skeletal muscles.
*Voluntary.
What is the function of the autonomic sensory neurons?
Convey info from ANS sensory receptors to the CNS.
What is the function of the autonomic motor neurons?
Conduct nerve impulses from CNS to smooth, cardiac muscle, and glands.
*Involuntary.
What is the enteric nervous system nicknamed?
The brain of the gut.
How many neurons are in the enteric plexus?
Millions.
How far does the ENS extend through the GIT?
Most of its length.
What are the functions of sensory neurons in the ENS?
- Monitoring chemical changes.
- Monitoring stretching of walls in GIT.
What are the functions of motor neurons in the ENS?
- Governs smooth muscle contractions.
- Governs GIT secretions.
- Governs endocrine cell activity.
What are the 2 branches of the ANS?
- Sympathetic (Fight or Flight).
- Parasympathetic (Rest & Digest).
What are the 4 features nerves can be classified on?
- Size and shape.
- Dendritic branching variations.
- Axon length.
- Function.
What are the 3 functions a neuron could have?
- Sensory.
- Interneuron.
- Motor.
How are neurons typically classified?
According to the number of processes extending from their cell body.
What are the 3 classifications of neurons?
- Bipolar.
- Multipolar.
- Unipolar.
What is a bipolar neuron?
A neuron that has 1 axon and 1 dendrite with the cell body in the middle of the two.
What is a multipolar neuron?
A neuron with one axon and several dendrites coming out of the neuron cell body.
*The classic neuron.
What is a unipolar neuron?
A sensory neuron that begins as bipolar and develops a fused axon and dendrite that splits into 2 branches. The periphery extending branch develops dendrites, and the CNS extending branch develops synaptic knobs.
Where is the trigger zone on a unipolar axon?
At the junction of the dendrites and axon.
Where are the cell bodes of unipolar neurons located?
Ganglia of the cranial and spinal nerves.
Where are bipolar neurons found?
The retina of the eye.
Where are multipolar neurons found?
The brain and spinal cord.
What are neuroglia?
Nervous system support cells.
What do neuroglia do during injury or disease?
Multiply to fill the space formerly occupied by neurons.
How many types of neuroglia are found in the CNS?
4.
How many types of neuroglia are found in the PNS?
2.
What are the 4 neuroglia found in the CNS?
- Astrocytes.
- Ependymal cells.
- Microglia.
- Oligodendrocytes.
What CNS neuroglia is the largest and most numerous?
Astrocytes.
What are the functions of astrocytes?
- Support neurons.
- Help create the BBB.
- Regulates the growth, migration, and interconnection among neurons in the brain of an embryo.
- Helps maintain appropriate chemical environment for nerve impulse generation.
- Learning and memory.
What is the function of oligodendrocytes?
Forming and maintaining the myelin sheath around CNS axons.
What is the function of microglia?
Phagocytosis of old or foreign material.
What areas of the body do the ependymal cells line?
- Ventricles of the brain.
- Central canal of the spinal cord.
What is the function of ependymal cells?
Produce, monitor, and assist in CSF circulation.
What are the 2 neuroglia found in the PNS?
- Satellite cells.
- Schwann cells.
What are the functions of satellite cells?
- Regulates the exchange of material between neuronal cell bodies and interstitial fluid.
- Structural support.
- Surround the cell bodies of neurons of PNS ganglia.
What is the function of Schwann cells?
To myelinate the PNS axons.
What are graded potential?
The potential as it builds up to the threshold. The localized membrane potential changes that, when enough occur in a small area in a short period of time, results in threshold being reached.
What are upper motor neurons?
Somatic motor neurons that originate in the cerebral cortex and communicate motor messages to lower motor neurons.
What are lower motor neurons?
Somatic motor neurons originating in the spinal cord that directly innervate skeletal muscle and allow for movement.
