Neuro A&P Flashcards
Astrocytes
fill the spaces between neurons and surrounding blood vessels.
-part of the blood brain barrier
-provide rapid transport of nutrients
-scar formation
-seizures
Oligodendroglia
form myelin sheath of the brain and spinal cord
-myelin is white “white matter”
-neurons are grey “grey matter”
Microglia
tissue macrophages in the CNS
Ependymal
cells that line the ventricles of the brain and choroid plexuses
-production of CSF
Schwann Cells
formation of myelin sheath in the PNS
-metabolic support
-salutatory conduction
Motor neurons
Efferent neurons
CNS–> body
Sensory neurons
Afferent Neurons
body –> CNS
Chemical synapses
only work in one direction
-neuron communication
Acetylcholine
Excitatory and Inhibitory
located in skeletal muscle (excitatory) brain, spinal cord and heart (inhibitory)
-deactivated by acetylcholinesterase
Monoamines
synthesizes from amino acids
include: histamine, serotonin, dopamine, epinephrine, norepinephrine
–> found in various parts of the brain affect learning, emotions and motor control
Dopamine Neurotransmitter
monoamine
-deficiency in dopamine leads to Parkinson’s disease
Epinephrine and Norepinephrine Neurotransmitters
motor control and sympathetic pathways
fight/flight
Glutamate neurotransmitter
Glutamate amino acid
-located in brain and spinal cord
-excitatory effects
-drugs that block glutamate treat Amyotrophic lateral sclerosis (ALS)
GABA neurotransmitter
Gamma aminobutyric acid (amino acid)
-located in CNS
-mainly inhibitory
-drugs that increase GABA are used to treat seizures
Glycine neurotransmitter
amino acid
-located in spinal cord
-inhibitory at the post synaptic membrane
Corpus Callosum
responsible for maintain communication between the right and left hemisphere
Frontal Lobe
Voluntary skeletal action contralaterally, communication (talking, writing) emotions, intellect, reasoning, judgement and behavior.
-personality
-Broca’s area –> expressive aphasia (responsible for speech)
Parietal Lobe
interprets tactile sensation
touch, pain, temperature, shapes and 2-point discrimination
-senses
Occipital lobe
ability to read with comprehension
primary visual center
-vision
Temporal lobe
interprets impulses from the ear
-hearing
-Wernicke’s Area
–> Wernicke’s aphasia
hard to understand and communicate
Basal ganglia
function: work with cerebellum to modify voluntary movements and have a role in cognition and emotions
-inhibitory effect of thalamus
structures: caudate, putamen, nucleus accumbent, globus pallidus, substantia nigra, subthalamic nucleus, claustrum, amygdala.
limbic system
between cerebrum and diencephalon
responsible for long term memory, primitive behavioral responses, visceral reactions to emotion, motivation, feeding behaviors, biological rhythm and sense of smell.
Pia Mater
covers the brain directly
-some arterial supply
Arachnoid Mater
middle meninge and is avascular
Dura Mater
outer most meninge contains the venous system
subarachnoid space
has arteries and carries CSF
Subdural space
contains venous circulation
subdural hematoma (venous blood)
Epidural space
has some intracranial arteries
epidural hematoma (arterial blood)
Diencephalon
thalamus and hypothalamus
Thalamus: central relay point (screens and directs impulses to and from the cerebral cortex)
Hypothalamus: regulates water balance, appetite, vital signs, sleep cycles, pain perception, emotional status and links the CNS to the endocrine system
Brain Stem
Midbrain, the pons, medulla, and reticular formation
10 cranial nerves –> brain stem
Midbrain
relay center for eye and ear reflexes
cerebrum — midbrain —> pons, medulla, cerebellum and spinal cord
The Pons
reflex actions, participates in balance, breathing regulation and maintenance of posture
Medulla Oblongata
respiratory functions, heart rate, blood pressure, swallowing, gag and cough reflex
Reticular Formation
collection of nerves within the brain stem
-viral reflexes such as cardiovascular and respiratory functions
-responsible for wakefulness
RAS (reticular activating system)
Cerebellum
behind brainstem
-coordination, smoothing of voluntary movements, maintenance of equilibrium and maintenance of muscle tone.
CSF
supportive and protective cushion for CNS
-found in subarachnoid space and within brain cavities and canals of the brain
-Choroid plexus site of CSF secretion from blood
600 ml of CSF daily
150 in ventricles daily
Spinal Cord Vertebrae
7 cervical
12 thoracic
5 lumbar
5 fused sacral
4 fused coccygeal
33 total vertebral
Vertebral disk between each vertebrae absorb shock and provide cushion
disk can cause significant back problems
spinal cord extends from the medulla oblongata to lumbar vertebrae and extends to cauda equina (bundle of nerves that extends from the end of the spinal cord)
Posterior/Dorsal Horns
made of sensory nerves carry afferent stimuli from the body to the brain
specifically fine touch, vibration, and proprioception
Anterior/Ventral Horns
made of motor neurons and carry efferent stimuli from the brain to the body
mainly controls skeletal muscle
Spinothalamic Tract
ascending (sensory) tract
-anterior spinal thalamic tract
-lateral spinal thalamic tract
sensations of pain, temperature, crude and light touch to the thalamus
sensations crossover immediately!
deficits will be contralateral in this tract
Posterior Column
ascending (sensory) tract
-fasciculus gracilis
-fasciculus cuneatus tracts
carries sensations of position, vibration, stereognosis and fine touch to the thalamus –> cerebral cortex
crossover of impulses is high deficits, will be ipsilateral to a lesion (problem in the spinal cord)
lesion in cerebral cortex –> deficit contralaterally (problem in the brain)
Pyramidal Tract
Descending (motor) tract
-Corticospinal
-Corticobulbar tract
impulses from the brain are sent via this tract and control voluntary movements of purpose and skill
impulses crossover at the spinal cord and brain stem defects in this tract will be contralateral
upper motor neurons
-motor neurons that are located above the synapses
deficits result in spastic paralysis, hyperreflexia, and the presence of a babinski reflex
ex: ALS (Amyotrophic Lateral sclerosis)
lower motor neurons
-motor neurons that are located below the synapse
deficits manifest as: flaccid paralysis, muscular atrophy, fasciculations, fibrillations, or hyporeflexia
ex: Poliomyelitis
Extrapyramidal Tract
Descending (motor) tract
-rubrospinal tract
-reticulospinal tract
-tectospinal tract
-vestibulospinal tract
tract responsible for gross motor movements, automatic motor movements, facial expression, posture, muscle tone, speech, and swallowing
crossover at the brain stem and spinal cord junction, deficits will manifest contralaterally
ex: spastic increase in muscle tone, abnormal posture, involuntary movements, tremors, normal or increased DTR
Ex: Parkinson’s disease
Peripheral Nervous System
12 cranial nerves and 31 spinal nerves
12 cranial nerves conduct motor and sensory impulses to and from the brain/brain stem
31 pairs of spinal nerves
carry impulses to and from the spinal cord
-nerves that innervate particular parts of the skin are called dermatome
-Somatic NS control voluntary muscles movements and all external sense organs (5 senses)
-Autonomic NS consist of motor neurons that control internal organs (heart, smooth muscle, glands, uterus, intestine and bladder)
ANS further divides to SNS and PSNS
Sympathetic NS
-fight or flight
-excitatory function
-increases energy and HR
Parasympathetic NS
-relaxation
-conserves energy and slows HR
neural tube
forms at 3-4 weeks gestation
forms entire nervous system
caudal end –> brain
forebrain
forms at 2-3 months from neural tube
neuronal proliferation
3-5 months and synapses form at 5 months
brain develops rapidly –> head fastest growing part of the body during infancy
half of post-natal growth in 1st year
90% complete by 6 years
greater cerebral O2 consumption
Myelin
formed in the post-natal period and takes many years to complete
Posterior Fontanels
close at 2-3 months
Anterior Fontanels
close at 18 months
reflexes present at birth
stepping ( 6 weeks) , moro (3 months), sucking, rooting (4 to 7 months), palmar grasp (6 months), and plantar grasp (10 months)
Tonic neck
2 months to 5 months
neck righting
4-6 months to 24 months
landau
3 months to 24 months
Parachute reaction
9 months for life
Structural changes associated with aging
Decreased brain weight and size (especially in the frontal lobes), fibrosis and thickening of the meninges, widening sulci and narrowing gyri, and increase in the size of the ventricles
Cellular changes associated with aging
include a decrease in the number of neurons, a decrease in the amount of myelin, decreased number of dendritic processes and synaptic connections, increased neuroinflammation, formation of intracellular neurofibrillary tangles, imbalance in neurotransmitters, declines in melatonin levels, and atrophy of the epithelial cells in the choroid plexus.
Cerebrovascular changes associated with aging
arteriosclerosis, increased permeability of the blood-brain barrier, decreased vascular density
Functional changes associated with aging
decreased deep tendon reflexes, skeletal muscle atrophy, progressive decrease in taste and smell, decreased vibratory sense, decreased color vision and accommodation, decreased control of gait and posture, sleep disturbances, and memory impairments.
