Anatomy Test 4: Nervous System Flashcards
What does the CNS consist of?
Brain and spinal cord
contains many neurons
Nervous system’s functions
sensation- internal and external
Integration- interpretation and response to sensation
Motor control- responses via muscular control
What happens in the CNS?
Sensory information is interpreted, thoughts and emotions are produced, initiate motor impulses to control muscles and glands
What does the PNS consist of?
Nerves between CNS and receptors/factors. Emerge from the brain and spinal cord
What are the two cell types of nervous tissues?
Neurons- nerve cells
Neuroglia- support and protect (glial cells)
Which do you have more of: glial cells or neurons?
Glial cells
Astrocytes
Star shaped glial cells.
Wrap around neurons
Insulation and isolation from other neurons and fluids in which they are Immersed.
Form a protective shield – blood brain barrier
Provide scaffolding- Physical support, repair, maintenance, and growth and development
Oligodendrocytes
Provide the myelin sheathing (insulation) for CNS neurons.
Wrap around the axons of neurons.
Improve speed and action potential, or nerve impulse
What do you myelinated axon’s make up?
White Matter
What do you unmyelinated areas make up?
Gray matter area
Nodes of Ranvier
Spaces between wrappings that are not sheathed
Ependymal cells
Ciliated glial cells lining the ventricles of the brain.
They assist in creating and circulating cerebrospinal fluid
Schwan cells
Wrap themselves completely around the axons.
Similar in function to oligodendrocytes in the CNS
List the sensory neuron’s
A.k.a. afferent.
Somatic
Visceral
Aka efferent
motor neurons
Somatic neurons
From the outer body, mostly skin senses and body positions
Visceral neurons
From internal organs.
Information about internal visceral conditions
Motor neurons
Efferent.
Carry impulses from the CNS to the muscles and glands
What do visceral effectors include?
Smooth muscle, cardiac muscle, and glands.
All under unconscious control
Do interneurons belong to the CNS or PNS?
The CNS only.
Connect sensory and motor neurons
Major regions and landmarks of the brain
Telencephalon, diencephalon, mesencephalon, metencephalon, Myelencephalon
Telencephalon
Cerebrum
Conscious thought,
memory,
skeletal muscle contractions
Cerebrum
Largest region of the brain.
Two hemispheres connected by corpus callosum.
Conscious thought and all intellectual processes. Processing of somatic sensory and motor information
Cerebral cortex
Hey thin blanket of gray matter folded into gyri and sulci
Gyri
Sulci
G- wrinkles
S- depressions
Association fibers
Only connects nerve cells within one hemisphere
Commissural fibers
Transmits information from left to right hemispheres
Projection fibers
Link cerebrum with other regions of the brain and spinal cord
Diencephalon
Thalamus
Hypothalamus
Epithalamus
pineal gland
internal clock of day-night cycles.
Reproductive function
Thalamus
acts as a relay station for ascending sensory information
Hypothalamus
small but very important Integrates the ANS with the CNS Involuntary somatic motor activities control of automatic functions coordination of activities of nervous and endocrine system secretion of hormones production of emotions and behavioral drives (thirst, hunger, sex) Regulation of body temperature
Mesencephalon
Midbrain
Visual and Auditory
Maintenance of consciousness
Metencephalon
cerebellum and pons
Balance and coordination
Cerebellum
2nd largest brain region
adjusting the postural muscles
programming and fine-tuning voluntary and involuntary movement
Pons
Bridge between the cerebellar hemispheres and mesencephalon, diencephalon, cerebrum, and spinal cord
Relays sensory information to thalamus
autonomic centers for regulation of visceral functions
Myelencephalon
medulla oblongata
Medulla oblongata
relays sensory information to the thalamus
autonomic centers for regulation of visceral functions
what are Ventricles of the brain?
Hollow areas within the brain
continuous with the central canal of the spinal cord
What produces cerebrospinal fluid and where?
specialized structures choroid plexus,
within the ventricles of the brain
What does Choroid plexus mean?
Choroid- vascular
Plexus- braid, network
What is the brain protected by?
cranial bones
What are the three layers of connective tissue that surround the brain and spinal cord and what do their names mean?
Dura mater- tough mother
arachnoid- spider like
pia mater- gentle mother
What do the connective tissues surrounding the brain and spinal cord do?
hold blood vessels nerves, and CSF
Dura mater has how many layers?
two
Where is the endosteal layer located?
It is fused to the periosteum of the cranial cavity (layer on the inside of the skull on the cadaver)
Meningeal layer
Has blood above it
What does the CSF do?
Suspend and cushion the brain
Transports nutrients
What happens to CSF if reabsorption is inadequate?
It will accumulate the damage brain tissue by compression (hemorrhage)
What happens if fluid accumulates before closure of fontanelles in babies?
cranium will be greatly enlarged (hydrocephalus)
Are cranial nerves a component of the CNS or PNS?
PNS
Where do cranial nerves originate?
originate in and connect to the brain rather than the spinal cord
List the Cranial Nerves
Olfactory Optic Oculomotor Trochlear Trigeminal Abducens Facial Vestibulocochlear Glossopharyngeal Vagus Accessory Hypoglossal
What does the Spinal cord contain?
all ascending and descending tracts of CNS
What are the expanded areas on the spinal cord called?
Enlargements
what is the Cauda Equina?
hair-like structures
where are enlargements of the spinal cord found?
where grey matter of cord is expanded to incorporate more sensory input for innervation of limbs
Cervical, brachial, and lumbar enlargements
cervical is the largest
Where are cell bodies of the sensory neurons located?
In the dorsal root ganglia
Where are cell bodies of motor neurons found in?
ventral horns of the gray matter
What does each segment of the spinal cord have?
An associated pair of dorsal roots and a pair of ventral roots
What do each pair of the dorsal and ventral roots do?
join together to leave the intervertebral foramen as a spinal nerve
What is a spinal nerve?
a mixed nerve, containing fibers from both dorsal and ventral roots
What does a peripheral nerve consist of?
an outer epineurium enclosing a variable number of fascicles
What is a nuclei?
masses of non myelinated cell bodies, neuroglia, and dendrites
Where are nuclei located?
inside the spinal cord
What are nuclei organized into?
Points called gray horns
Anterior lateral, and posterior horns
What is the organization of white matter?
Very very organized into columns
Do neural reflexes require the brain?
NO
List the steps of a reflex
- arrival of stimulus; activation of a receptor
- Sensory neuron activated and impulse taken to spinal cord
- Processing the information
- processing activates the motor neuron
- Causes response of peripheral effector organ
