Unit 9: Nervous Tissue Flashcards
Central nervous system includes
Brain, spinal cord
Peripheral nervous system includes
1) somatic nervous system (SNS)
2) autonomic nervous system (ANS)
3) enteric Nervous System (ENS)
Somatic nervous system (SNS)
Afferent neurons; efferent neurons; interneurons, head, body wall, limbs
Autonomic nervous system (ANS)
Motor neurons, involuntary, smooth cardic muscle/glands
1) sympathetic division
Flight/fight response - speeds up
2) parasympathetic division
Mellow/relax - slows down
Enteric nervous system (ENS)
Brain of the guy; controls digestion from beginning to end
Ganglia
Small masses of neuronal cell bodies located outside the brain/spinal cord; closely associated with cranial/spinal nerves
2 types of nerve cells
Neurons, neuoglia
Which nerve cell transmits electrical signals
Neurons
Neuron: cell body
Process signal received
Neuron: dendrites
Receive signal
Neuron: axons
Transmits signal
Neuron: Axon terminal
Carries signal to destination (synapse)
Sensory Afferent neurons
Convey APs into the CNS through cranial/spinal nerves
Motor/efferent neurons
Convey APs away from the CNSmto effectors (spinal/glands) in the periphery through cranial/spinal nerves
Interneurons
Mainly located within the CNS between sensory/motor neurons; make decisions between affecent/effecent
Synapse
Site of communication between 2 neurons or between a neuron and another effector
Synaptic vesicles
In axon terminals, tiny membrane enclosed sacs stores packets of neurotransmitter chemicals
Neurotransmitter
In between synapse, action potentials, communicate at the synapse, re establish the AP in the postsynaptic cell
Schwann Cell
Neuroglia; produce myelin in PNS
Astrocyte
Neuroglia, support neurons in CNS-blood brain barrier
Ependymal cells
Neuroglia, form/circulate spinal fluid
Microglia
Neuroglia, participate in phagocytosis in brain
Oligodendrocyte
Produce myelin in CNS
Myelination
The process of for,in a myelin sheath which insulates and increases nerve impulse speed, insulated nerves have faster signal
Multiple sclerosis
Autoimmune destruction/degeneration of myelin; slows down nerves
Nerve regeneration
Largely dependent on the Schwann cells in the PNS; doesn’t occur at all in the CNS where astrocytes create scar tissue, repairs nerve cells as much as possible
Demyelination
The loss/destruction of myelin sheaths around axons
White matters
Formed from aggregations of myelinated axons from many neurons; inside brain outside spinal cord
Gray matter
Lacks myelin; formed from cell bodies and dendrites, decision making
Action potential (AP)
A short lasting event in which the electrical membrane potential of a cell rapidly rises and falls
Ion channel
Present in the plasma membrane; allows specific ions to move across plasma membranes
Nerve impulse
The electrical wave transmitted along a nerve fibre comes after stimulation; moves higher-lower concentration low-high concentration
Polarized
Resting but primed - ready to produce action potential
Depolarization
Sodium channels open letting sodium rush in; makes inside positive; potassium leaks out
Polarization
Potassium channels open; sodium channels close;’potassium comes in sodium pumps out
What stage has a refractory period
Depolarization
Synapse
A structure that permits a neuron (nerve cell) to pass an electrical signal or chemical signal to another cell
Neurotransmitter 2
Chemicals that allow the transmission of signals from one neuron to the next across synapses
Agonist
Any chemical that enhances or stimulates the effects at a given receptor
Antagonist
A chemical that blocks or diminishes the effects at a given receptor
Comes medullaris
Cone shaped structure at the lower end of the spinal cord
Location and length of adult spinal cord
Medulla oblong are to foramen magnum to conus medullaris
End of spinal cord called
Conus medullaris
Where does the spinal cord end
L1-L2
Sensory information travels in which direction
To the brain
Motor information travels in which direction
Away from the brain
Meninges
1) dura matter (outer)
Encloses entire cord
2) arachnoid matter (middle)
Spinal fluid circulation
3) pita matter (inner)
Supplies blood/nutrients
Which space contains cerebral spinal fluid
Arachnoid matter
Epidural space
Runs between the dura matter and superficial ligamentum flavum
Subdural space
Between dura/arachnoid
Filum terminale
Extension of the pia matter, extends inferiority and blends with the arachnoid and dura to anchor the spinal cord to the coccyx
Cuada equine
“Horses tail” roots of the lower spinal nerves that angle down alongside the filum terminale
3 steps to nervous tissue
1) a sensory function detects internal and external stimuli (detection)
2) interpretation is made (analysis)
3) a motor response occurs (reaction)
How do spinal nerves attach to the spinal cord
1) roots - two bundles of axons
2) rootlets - s,alter bundles of axons
What is the dorsal root ganglion
Contains only sensory axons, conducts nerve impulses from sensory receptors; skin, muscles, internal organs to the central nervous systems
Location of a lumbar puncture
Between L3-L4
Epidural
Labor pain medication, placed between bones at posterior spine
Meningitis
Inflammation of the brain and spinal cord membranes
White matter
Consists of millions of myelinated nerve fibers
Gray matter
Decision making, de myelinated made up of dendrites and cell bodies
Tract
A bundle of neuronal axons located at a specific place all traveling to the same place
Naming of tracts
Spinalthalamic and corticospinal
Dermatome
An area of skin that is inneruated by a single spinal nerve indicated by the letters and a number of a particular segmental nerve
Transection
Ascending/descending tracts are partially/completely severed
Base of skull = death, upper cervical = quadriplegic lower =’paralysis
Quadriplegia
Total body paralysis
Paraplegia
Partial body paralysis
Plexus
Formation of the segmental nerves to form a “brain rope”
Cervical plexus
Anterior branches of c1-c5 head neck diaphragm
Phrenic - arises from cervical to supply diaphragm (c3 c4 c5 keep them alive)
Brachial
Anterior branches c5-c8 t1 shoulder upper limbs
Auxiliary (armpit)
Radial/ulnar (lower arm)
Median (wrist)
Lumbosacral
L1-L4 abdominal wall external genitalia, lower limbs
Sciatic - L4-L5 s1-s4 sciatic nerve
Femoral - lumbar plexus
Erbs palsy
Injury to brachial/peripheral nerves at birth, arm paralysis
Funny bone
Humerus
Carpal tunnel syndrome
Median nerve injury, repetitive motion issues
Reflex
Fast involuntary response to a stimulus
Patellar reflex
Leg extends in response to stretch of the patellar tendon
Achilles reflex
Contraction of the calf when force is applied to Achilles’ tendon
Babinski reflex
Normal curl of the big toe when stimulated (downward)
Frontal lobe and executive functions
Associated with higher (executive) functions, self control, planning, reasoning, abstract thought
Blood supply
1) internal carotid arteries - supplies blood to brain (anterior)
2) vertebral arteries - supplies blood to brain (posterior)
3) internal jugular - venous return
Blood brain barrier
Serves to isolate the parenchyma from many substances in the blood that would normally be able to gain access
Ventricles
Internal cavities in the brain
Cerebrospinal fluid
A clear fluid that circulates through the internal cavities of the brain and spinal cord, flows over and around the brain in subarachnoid space
Cerebrospinal fluid is made from what cells
Ependymal cells
Cerebrospinal fluid is made where
Choroid plexus - network of capillaries that line ventricles
Hydrocephalus
Occurs when congenital abnormalities, head injury, meningitis, episodes of bleeding in the brain
3 parts of the brain stem
Midbrain, pons, medulla oblongata
Pyramids, function and location
E get all bulges, formed by the largest motor tracts in the body, left pyramid cross over to right, right to left, opposite hemispheres control opposite sides
Medulla oblongata functions
1) cardiovascular center - controls rate/force of heart beat, diameter of blood vessels
2) respiratory rhythmicity center - controls rate/rhythm of breathing
3) vomiting, coughing, sneezing centers
Pons functions
Help control breathing
Reticular foramen and RAS
A netlike arrangement of neuronal cell bodies and small bundles of myelinated axons
RAS - maintains consciousness, prevents sensory overload by filtering out insignificant information
Cerebellum
Located ?
Function - compares intended movements with what’s happening, regulates posture, equilibrium, and balance
Diencephalon
Located near the midline of the brain
1) thalamus - relay station for all sensory impulses to cerebral cortex
2) epithalamus - superior/posterior to thalamus, pineal gland (melatonin) habenular nuclei (emotional responses to smell)
3) hypothalamus - controls many homeostasis functions, controls ANS coordinate between NS/endocrine systems, controls body temp, hunger/thirst, internal circadian rhythm
What gland is attached to the hypothalamus
Pituitary gland
