Lab 1- Nervous Tissue Flashcards
Cell body
Constitues nucleus and cytoplasm.
Nucleus
DNA-containning structure of cell body.
Axon hillock
Conic area of origin of axon.
Dendrite
Branching extensions of cell body providing structural pathway for afferent info.
Axon
Structural pathway for efferent info.
Neurolemmocyte (Schwann cell) and Myelin Sheath
Cell that surround and myelinated axons in PNS.
-Myelin: insulates and rapid transmission of impulses.
Nodes of Ranvier (neurofibril nodes)
Gap in myelin sheath allows formation of new AP, increases rate of impulse transmission.
Telodendria
Distal branching of neural axon.
Axon terminals = synaptic end bulbs
Axon terminates, communicates with subsequent cells.
neurotransmitters
What is another word for sensory neuron?
Afferent
What is another word for motor neuron?
Efferent
What type of neuron is between sensory and motor neurons?
Interneurons (association neurons)
Epineurium
Covering of entire nerve.
Perineurium
surrounds group of nerve fibers forming a fascicle.
Endoneurium
Wrapping of each nerve fiber.
Fascicle
Small bundle of nerve fibers.
Axon
long & single nerve-cell process.
Myelin sheath
Fatty white substance surrounding axon.
Tract
Collections of axons in CNS.
Nerve
Collections of axons in PNS.
Ganglia
Collections of neuron cell bodies in PNS.
Nucleus/nuclei
Collections of neuron cell bodies in CNS.
Cerebrospinal fluid (CSF) is found in the subarachnoid space, which is between the ________ and ________.
Arachnoid mater & Pia mater.
The epidural space is between ________ and ______.
Vertebra & Dura mater.
Ventral root
(anterior root)
Efferent = motor
Dorsal root
(posterior root)
Afferent = sensory
Dorsal root ganglion
(posterior root ganglion)
swelling of lateral SC containing sensory neuron cell bodies.
Spinal nerve
Merging of ventral and dorsal roots. (mixed nerve)
Does the dorsal root contain sensory or motor neurons?
Sensory
Does the ventral root contain sensory or motor neurons?
Motor
What is in the dorsal root ganglion?
collection of cell bodies in PNS.
What is gray matter composed of?
cell bodies & unmyelinated axons.
In which two spinal cord regions are the lateral gray horns present?
Thoracic & Lumbar.
What do the ascending tracts of the white columns convey?
Sensory info.
What do the descending tracts of white columns convey?
Motor info.
Name 2 diseases that cause destruction of the anterior horn motor neurons.
- Polio
- ALS
Polio
initial flu like symptoms
ALS
unable to initiate and control muscle movement.
How many pairs of spinal nerves are there?
31
how many cervical?
8
how many thoracic?
12
how many lumbar?
5
how many sacral?
5
how many coccygeal?
1
Are spinal nerves sensory, motor or both?
Both
Describe how cervical spinal nerves are named/numbered.
numbered/named by the vertebrae below
-except for C8 (between C7 & T1)
Describe how thoracic, lumbar, sacral, and coccyx spinal nerves are named/numbered.
Named after vertebra above.
The spinal nerves then branch and become ______.
Dorsal ramus and ventral ramus.
Posterior (dorsal) innervate ________.
The back
Anterior (ventral) rami will branch and anastomose to form________.
Nerves that go to appendages.
brachial Plexus C5-T1
- Axillary nerve (C5-C6)
- Radial nerve (C5-T1)
- Musculocutaneous nerve (C5-T1)
- Median nerve (C6-T1)
- Ulnar nerve (C8-T1)
Which 2 muscles does the axillary nerve innervate?
Deltoid & Teres minor
hat is the sensory distribution of the axillary nerve?
Skin of shoulder
The musculocutaneous nerve innervates the _______ muscles of the arm.
Flexor
What is the sensory distribution of the musculocutaneous nerve?
Lateral surface of forearm.
What is the sensory distribution of the radial nerve?
Posterolateral hand including first digit.
The median nerve innerevates the ______ muscles of the forearm.
flexor
What is the sensory distribution of the median nerve?
Anterolateral surface of hand & posterior 2nd, 3rd, 1/2 of 4 digits.
The median nerve goes though the ______ tunnel of the wrist.
Carpal
What is the sensory distribution of the ulnar nerve?
Anterolateral and postero medial surface of hand, 1/2 of 4th & 5th digits.
Lumbar Plexus (T12-L4)
- Femoral nerve (L2-L4)
2. Obturator nerve (L2-L4)
What does the femoral nerve innervate?
sensory = anterior medial thigh motor = Quadriceps
What the the obturator nerve innervate?
Sensory = medial surface of thigh. Motor = adductors of hip
Sacral Plexus (L4-S4)
- Sciatic nerve (L4-S3)
- tibial nerve: posterior muscles of leg
- common fibular nerve: lateral and anterior muscles of the leg. innervates the buttock, lower limb, pelvis, perineum.
Sympathetic chain
- Sympathetic chain ganglion
- Rami communicates
- White ramus (preganglionic)
- Gray ramus (postganglionic)
What is a reflex?
An action that is performed as a response to a stimulus and without conscious thought.
Receptor
site of stimulus
Sensory neuron q
Transmits the afferent impulse to the CNS.
Control (integration) center
in the CNS where the sensory info is received and transferred to the motor neurons.
Motor neuron
Conducts efferent impulses from the integration center to an effector.
Effector
Muscle fiber or gland that responds to the efferent impulse.
What is an innate reflex? example
Connections that form between neurons during development.
EX: blinking, swallowing
What is an acquired reflex? example
Learned overtime
EX: riding a bike
What is a visceral (autonomic) reflex?
Controls actions of smooth muscle, glands, and adipose tissue.
EX: digestion, blood pressure
What is a somatic reflex?
control skeletal muscle contractions (include superficial stretch reflexes)
What is a spinal reflex?
important interconnections and processing events occur in spinal cord.
What is a cranial reflex?
integration center located in brain
EX: pupil dilation, salivating
Describe monosynaptic reflexes
(fast) simplest reflex arc, sensory neuron synapses directly on a neuron.
Describe reflexes
Complexed with 1 or more interneuron between sensory and motor neurons. Interneurons involved can control several muscle groups and produce either excitatory or inhibitory polysynaptic potentials.
Describe a stretch reflex
(posture) stretching of a muscle activates a muscle spindle. Impulse transmitted by afferent fibers to spinal cord. Motor neurons in spinal cord cause stretched muscle to contract. Integration center causes antagonist muscle to relax (reciprocal inhibition).
Monosynaptic reflex: decreased reflexes should lead to suspicion that reflex arc has been affected. possible sensory nerve fiber or spinal cord gray matter (motor fibers), LMN lesions.
What is a muscle spindle?
bundle of specialized skeletal muscle fibers that act as sensory receptors.
ankle jerk (monosynaptic)
test spinal nerves S1 and S2
Knee jerk (patellar reflex) (monosynaptic)
test spinal nerves L2, L3, L4
Biceps jerk
Test spinal nerves C5 and C6
What conditions would diminish reflexes?
Hyporeflexia
What conditions would cause increased reflexes?
Hyperreflexia
What is a tendon reflex?
causes muscle to relax
-monitors external tension produced during muscular contraction, prevents tearing or breaking if tendons.
Is the tendon reflex monosynaptic or polysynaptic?
Polysynaptic
What is a Golgi tendon organ?
stretch receptor in tenon
Describe a withdrawal reflex?
flexor reflex- pain receptors activated causing automatic withdrawal of threatened body part.
What is reciprocal inhibition?
Interneurons in spinal cord prevent stretch reflex in antagonistic muscles.
Describe the crossed extensor reflex (ipsilateral and contralateral)
Complex reflex- maintains upright position if pain is generated in lower extremity. Pull foot back, the other leg responds to hold you upright. (step on glass)
