Nervous System Flashcards
Two Main Divisions
- Central Nervous System (CNS)
- Brain + Spinal Cord - Peripheral Nervous System (PNS)
- Cranial Nerves
- Spinal Nerves
- Further subdivided into the somatic and autonomic nervous systems
CNS: Brain
- largest organ of the nervous system
- located in the cranium
- four major structures
1. cerebrum
2. cerebellum
3. diencephalon
4. brain stem - integration of almost every physical mental activity of the body
CNS: Spinal Cord
- long narrow column of neural tissue within the spinal cavity or canal
- extending from the brain stem to the second lumbar vertebra in the spinal column
- protected by the bony structure of the vertebral column
- protected and nourished by the meninges
- relay station for sending and receiving electrical signals between the brain and body
CNS: Meninges
Three layers of protective membrane covering the brain and spinal cord
- Dura mater (outermost layer)
- Arachnoid (middle layer)
- Pia Mater (innermost layer)
Peripheral Nervous System (PNS)
Cranial Nerves
-12 pairs that emerge from the brainstem
-named according to location or function
Spinal Nerves
-38 pairs that emerge from the spinal cord
-named according to the vertebra from which they exit
Defined by the direction in which impulses travel:
-Sensory (afferent) neurons—to the CNS
-Motor (efferent) neurons—away from the CNS
PNS: Motor Neurons send impulses:
- Somatic nervous system (SNS)
- Autonomic Nervous System (ANS)
PNS: Motor Neurons send impulses; Somatic Nervous System (SNS)
regulates skeletal (striated) muscles (voluntary actions) such as walking and talking (how you move)
PNS: Motor Neurons send impulses; Autonomic Nervous System (ANS)
regulates visceral (smooth) muscles (involuntary actions) such as heart rate and peristalsis (relaxation of muscles and intestine or another canal, push canal forward), and secretory activity
- consists of 2 subdivisions that regulate involuntary body functions and usually oppose the action of the other:
1. Sympathetic- fight or flight
2. Parasympathetic- rest + digest
PNS: Motor Neurons send impulses; Autonomic Nervous System 2 Subdivisions: Sympathetic
(fight or flight)
increases heart rate, constricts blood vessels, and raises blood pressure to deal with a crisis
PNS: Motor Neurons send impulses; Autonomic Nervous System 2 Subdivisions: Parasympathetic
(rest + digest)
slows heart rate, increases glandular secretions, relaxes sphincters
Cellular Structure Of The Nervous System: Neuron
- individual nerve cell
- interconnecting to form complicated networks called nerves that transmit electrical impulses throughout the body
Cellular Structure Of The Nervous System: Neuroglia
- Glial cells that provide a supportive framework for neurons
- responsible for protecting against infection by performing phagocytosis (engulfing and digesting unwanted substances; like a Pacman)
- unable to transmit electrical impulses
Four Types of Neuroglial Cells
- Astrocytes
- Microglia
- Oligodendrocyte
- Ependyma
Neuroglial Cell: Astrocyte
- star-shaped cell
- numerous radiating extensions for attachment that are wrapped around the brain and capillaries
- part of the blood-brain barrier, which prevents harmful substances from diffusing into the brain
Neuroglial Cells: Microglia
- small interstitial cells
- phagocytic in nature, engulfing cellular debris, waste products, and pathogens within nerve tissue
- increase in number during injury or infection as cells migrate to the infected or injured area