Unit 1: The Nervous System Flashcards
Week 1
The Nervous System is Divided into 2 parts
- Central Nervous System (CNS)
- Peripheral Nervous System (PNS)
What does the Central Nervous System Consist of?
- Brain
- Spinal Cord
What does the Peripheral Nervous System Consist of?
- Cranial Nerves
- Spinal Nerves
- Autonomic nervous system (Sympathetic and Parasympathetic)
What does the Nervous Systems Do?
maintain homeostasis and coordination of the bodys functions
- CNS
- PNS
How does the Neurological System Work?
works through electrical and chemical messages transmitted from sensory organs to the brain and spinal cord
-reciprocating messages transmitted back to target organs and cells
The Peripheral Nervous System (PNS)
includes:
- 12 Cranial Nerves
- 31 Spinal Nerves
- Autonomic Nervous System (sympathetic/ parasympathetic/ enteric)
The Enteric System
“nervous system” of the gastrointestinal tract (GI)
- “second brain”
- autonomous control of the process of digestion
- segment of the autonomous nervous system (ANS)
Neurons
impulse conducting cells that facilitate communication within the nervous system
- Afferent: sensory
- Efferent: motor
Neuroglial cells
specialized cells that support and protect the neurons
Action Potential of a nerve cell
facilitates the transmission of information from a presynaptic neuron to a receptor
-occurs when the action of the sodium-potassium pump creates changes in the electrical balance between the outside and inside of the cell
The Synapse
site where electrical impulses (information) travel from one neuron to another neuron, gland, or muscle
Excitatory Neurotransmitters
open sodium channels, causing depolarization in the postsynaptic membrane, initiating an action potential
Inhibitory Neurotransmitters
open chloride channels, allowing negatively charged chloride ions into the cell
The Brain is divided into 3 parts:
- Cerebrum
- Cerebellum
- Brainstem
Cerebrum
largest portion of the brain
-covered by a thin layer of gray matter; cerebral cortex
-divided into 4 lobes: (highest functioning levels occur front to back)
>Frontal
>Parietal
>Temporal
>Occipital
-contains thalamus, basal ganglia, hypothalamus, and limbic system
Cerebrum: Frontal Lobe
located in the front area of the brain
- motor movement
- personality
- speech
- behavior
- judgement
- problem solving
Cerebrum: Parietal Lobe
located behind frontal lobe
- controls sensation and perception
- controls body position
Cerebrum: Temporal Lobe
located on the sides of the brain, beneath the parietal lobes
- controls sound recognition
- speech
- long term memory
Cerebrum: Occipital Lobe
located at the back of the brain
-vision (think “O” for optic)
Brain: Thalamus
relay center for sensory impulses to cerebral cortex
- pain
- temperature
- taste
- smell
- hearing
- equilibrium
- vision
- touch
- also relays info from the cerebellum and basal ganglia to the cerebral cortex; regulate motor control
Brain: Basal ganglia
regulates movement
- in coordination with the cerebellum, regulates movement
- sends information back and forth through the thalamus to the cerebral cortex
- basal ganglia is inhibitory; cerebellum is excitatory; coordinated movement is achieved through balance of both systems operating properly
- problems in basal ganglia = movement disorders
Brain: Hypothalamus
main regulator for the autonomic nervous system (ANS)
- sends signals to the brainstem; regulates heart rate and blood pressure
- regulates metabolism, reproduction, growth, and stress response
- thermoregulation
- regulation of food and water intake, sleep, memory, and emotional behavior
Brain: Limbic System
primary role in memory and emotions
-consists of the cingulate gyrus, hippocampus, and the amygdala
Brainstem structures
-medulla
-pons
-midbrain
-reticular formation
>10 cranial nerves originate in the brainstem
>injury here is life-threating
Brainstem: Medulla Oblongata
- respiratory and cardiac centers
- centers for vomiting, coughing, and swallowing
- continuous with the spinal cord; located at the level of and below the foramen magnum (opening in the skull that allows the spinal cord to connect with the brainstem)
Brainstem: Pons
relays all impulses between the brain and spinal cord
Brainstem: Midbrain
contains the nerve pathways between the cerebrum and the medulla oblongata
Brainstem: Reticular Formation
networks of neural cells
- motor control and coordination; maintaining balance and posture during movement
- respiratory and cardiac control
- pain modulation by providing a route of passage for pain signals from the lower body
- alertness and sleep by controlling some of the sensory stimuli that reach the cerebral cortex
Brain: Cerebellum
located at the base of the brain
- coordinated muscle activities
- gait and balance
- fine motor movements
- equilibrium
- nonmotor functions: speech, sensing, and emotions
- disturbance= gait and balance issues
Brain: Ventricles
where cerebral spinal fluid (CSF) circulates
-4 ventricles
Cerebral Spinal Fluid (CSF)
circulates through the 4 ventricles in the brain, into the subarachnoid space around the brain and into the central canal that houses the spinal cord
- colorless
- provides nutrients and cushioning to these structures
Ways that blood flows to the brain
- Arterial Circulation
- Circle of Willis
- Venous Blood Flow
Arterial Circulation of the brain
supplied by the right and left internal carotid arteries and right and left vertebral arteries
-internal carotid arteries (ICA) are the primary supply of blood to the cerebrum
Circle of Willis
critical collection of vessels
- major arteries providing blood flow to the brain
- 90% of strokes occur in the middle cerebral artery (MCA)
- internal carotid arteries and vertebrobasilar arteries join together via the posterior communicating artery at the base of the brain to form the circle of Willis
Venous Blood Flow
occurs through the dural sinuses (venous channels found between the dura mater and the brain)
-blood from the deep internal and external veins, and CSF from the subarachnoid space, empties into these channels to be transported back to the heart via the internal jugular vein
Spinal Cord
pathway that carries information to and from the brain and the body
- upper motor neurons: information from brain to spinal cord
- lower motor neurons: information from spinal cord to the muscle
- located within and protected by the vertebral column, a bony column
- begins at the brainstem and extends to the level of lumbar vertebrae 1 and 2
Decussation
crossover of pathways
- some pathways, during their ascent or descent, undergo “crossover” in the spinal column, which results in the right side of the brain controlling the left side of the body and vice versa
- contralateral
- ipsilateral
Contralateral
opposite sides of the body
Ipsilateral
same side of the body
Vertebrae
- protects the spinal cord
- allows flexibility and movement while providing support to the head and maintaining the body upright
Suture Lines
fibrous joints
-the cranium encases the brain with bones joined by suture lines
Protective Mechanisms
- Skull
- Vertebrae
- Meninges
- Meningeal spaces
- Blood-brain barrier
Protective Mechanisms: Skull
- encases and protects brain from injury
- made up of 8 cranial bones, joined by fibrous joints/suture lines
Protective Mechanisms: Vertebrae
skeletal structures that cover and protect the spinal cord
- provides the head with support
- allows flexibility and movement
- maintains body in upright position
Protective Mechanism: Meninges
fibrous membrane layers that protect the brain and spinal cord
-Dura Mater: outermost layer; tough, fibrous membrane; rests against the interior part of the skull
Dura Mater
tough, fibrous membrane
- outermost layer of the meninges
- rests against interior part of the skull
- consists of 2 layers: outer periosteal layer and meningeal layer
Protective Mechanism: Meningeal spaces
real or potential spaces between the membrane layers
- ex: epidural space (potential space that exists between the skull and dura mater)
- middle meningeal artery located here; if torn or damaged by trauma, a hemorrhage can occur
Protective Mechanism: Blood-brain barrier (BBB)
separates circulating blood volume from the extracellular fluid in the brain
-prevents passage of substances damaging to the brain (antibodies, toxins, or macrophages)
Spinal Cord: Dorsal Horn
nerve fibers that carry impulses into the spinal cord are contained within the dorsal nerve root that enters the cord through the dorsal horn
Spinal Cord: Ventral Horn
nerve fibers that carry impulses out of the spinal cord are contained in the ventral nerve root and exit the cord through the ventral horn
Dermatones
correlates to an area on the skin that is supplied by a specific spinal nerve
- maps where the nerve fiber provides sensation or feeling
- can assess sensory deficits
- dermatome chart
ANS: Sympathetic Nervous System (SNS)
“thoracolumbar system”; receives information from the thoracic and lumbar areas in the spinal cord
- prepares the body for stress or physical activity
- “flight or fight” response
- neurotransmitter released at the synapse is usually norepinephrine; fibers that secrete norepinephrine are adrenergic fibers
ANS: Parasympathetic Nervous System (PNS)
“craniosacral” system; receives information from the brainstem or sacral region of the spinal cord
-neurotransmitter released at the synapse is acetylcholine
