Unit Four Flashcards
Functions of the Nervous System
- Regulate body activities and maintain homeostasis
- Responsible for perception, behavior, and memories
- Initiate voluntary movements
how many cranial nerves are there?
12 pairs (24)
How many spinal nerves are there?
31 pairs (62)
What are the 3 basic functions of the nervous system?
- Sensory: detects internal and external stimuli via sensory receptors
- Integrative: After receiving sensory info, it integrates and processes the info
- Motor: Information is sent out to make a motor response
What are the two subdivisions of the nervous system?
- Central nervous system: the brain and spinal cord
- Peripheral nervous system: all the nervous tissue outside the central nervous system
What are Ganglia?
Small masses of nervous tissue consisting of neuron cell bodies, located outside the brain and spinal cord
Subdivisions of the Peripheral Nervous System
- Somatic Nervous system
- Autonomic Nervous system
- Enteric Nervous System
What is the somatic nervous system?
All sensory neurons that receive info from receptors from the head, body wall, limbs and special senses and motor neurons that innervate the skeletal muscles only
(It is voluntary)
What is the autonomic nervous system?
Sensory neurons that receive info from receptors in visceral organs (stomach, lungs, etc.) and motor neurons to smooth and cardiac muscles and glands.
(it is involuntary)
What is the enteric nervous system?
All the nerves that control the digestive system
(It is involuntary)
The autonomic nervous system is subdivided into:
- Sympathetic nervous system
- Parasympathetic nervous system
What is the sympathetic nervous system?
Sends the effectors commands for “fight or flight” responses
What is the parasympathetic nervous system?
- Sends the effectors commands for the “rest and digest” responses
- Tells heart to decrease heart rate when trying to sleep
Difference between neurons and neuroglia?
Neurons are nervous cells that possess electrical excitability where neuroglia are cells that support, nourish, and protect neurons
How can action potentials travel?
Due to movement of Sodium and potassium ions
What does the sodium and potassium ions move through
through ion channels in the plasma membrane between the extracellular fluid outside neuron and cytosol inside the neuron
What connects the axon to the cell body?
Axon hillock
Where do nerve impulses arise?
The trigger zone - junction of axon hillock and initial segment
What are axon terminals?
Processes at the distal end of the axon
What are synaptic end bulbs?
Bulb-like structures at the end of axon terminals
What are Synaptic vesicles?
Membrane-enclosed sacs that contain neurotransmitters
What are multipolar neurons?
Neurons with several dendrites and one axon
Where are multipolar neurons found?
In the brain and spinal cord
What are bipolar neurons?
Have one main dendrite and one axon
Where are bipolar neurons found?
In the retina and the inner ear
What are unipolar neurons?
Where the dendrite and axon are combines forming one projection from the cell body
Where are unipolar neurons found?
In ganglia of spinal or cranial nerves
What are neuroglia?
Cells that support and nourish neurons
Difference between neuron and neuroglia?
Neuroglia cannot propagate an action potential and are able to undergo cell division to replace injured or diseased neuroglia cells
What are the 4 types of CNS neuroglia?
- Astrocytes
- Oligodendrocytes
- Microglia
- Ependymal Cells
What are the largest and most numerous of the neuroglia?
Astrocytes
Function of astrocytes?
Neuroglia that support neurons, protect, and maintain appropriate chemical environment for nerve impulses
What do astrocytes regulate?
K (potassium) and Na (sodium) ions and uptake of excess neurotransmitter
What do oligodendrocytes do?
Form and maintain the multilayered lipid and protein myelin sheath (covering around the axon)
What does the myelin sheath do?
Insulate the axon - increases the speed of the action potential conduction
What do microglia do?
Phagocytes that remove cellular debris, microbes and damaged nervous tissue
What do ependymal cells do?
Produce and circulate cerebrospinal fluid
Where are ependymal cells located?
They line the ventricles in the brain and the central canal of the spinal cord
Types of neuroglia in the peripheral nervous system?
Schwann cells and satellite cells