Module 2 Lab Flashcards
act as pathways for the transmission of electrical impulses. Bears the responsibility of conveying sensory data from the peripheral to the central nervous system (CNS) and motor signals to muscles and glands from the CNS
nerve fibers
- Nerve fibers can be classified as
sensory
motor
transmit touch pressure and temperature
cutaneous nerve
convey sound signals
auditory nerve
– carry visual information from eyes to brain, that enables the frog to process visual stimuli
visual nerves
control voluntary movements
somatic nerves
regulate involuntary functions
autonomic nerves
combined sensory and motor functions
mixed nerves
nerve fibers serve as the sensory pathway, transmitting information from the peripheral receptors to the central nervous system
afferent
represent the motor pathways, carrying signals from the CNS to the muscles and glands
efferent
– touching the frog’s skin wherein the afferent nerve fibers kick into action quickly transmitting signals to its CNS, triggers a reflexive response
mechanical stimuli
behavioral adaptations such as the frog moving towards a warmer environment
thermal stimuli
when a frog detects a noxious odor, afferent fibers transmit signals to its central nervous system, signaling potential danger
chemical stimuli
- consist of a long axon encased in a myelin sheath, facilitating the transmission of impulses for movement, feeling, and other physiological processes throughout the body, making their nervous system crucial.
nerve fibers
natural physiological activity, and this natural function capacitates an organism for its continual survival by adjusting to its internal as well as external environment
response
considered as the most implicated but organized system in the bod
nervous system
- Two fundamental advantage of nervous system:
Nerve structure sensitivity to the environmental changes
Distinguishing property to transmit such excitation on from one portion of a cell to another or even throughout all the cells of a tissue/organ
physiological unit of the nervous system
neuron
not regarded as a functionality independent structures although such fiber may differ from one another in terms of histological structures and physiological behavior
nerve fiber
- Parts of a neuron with functions
dendrites
cell body
axon hillock
node of ranvier
cell membrane
nucleus
axon
myelin sheath
axon terminl
schwann cells
receive signals from other cells
dendrites
– organizes and keeps the cell functional
cell body
protects the cell
cell membrane
generates impulse in the neuron
axon hillock
allow diffusion of ions
node of ranvier
produces the myelin sheath
schwann cells
controls the entire neuron
nucleus
transfers signals to other cells and organs
axon
increases the speed of the signal
myelin sheath
forms junction with other cells
axon terminal
classified into two major groups based on the character of result of impulses
nerve fibers
materials for module 2
- Fresh frog
- Scalpel
- Scissor
- Pithing needle/probe
- Dissecting pan
- Gloves
- Cotton
- Kymograph
- Kymograph paper
- Filler paper
- Glass slides
- Inductorium
instrument for recording variations in pressure, drives or pulls the trace of a stylus on a rotating cylinder
kymograph
battery-operated apparatus containing induction coils used for producing a continuous pulsing electric current or a single pulse of current
inductorium
- Reagents used:
ringer’s solution
1% hydrochloric acid
2g NaCl crystals
ether/chloroform
intravenous or subcutaneous hydration and to expand the vascular compartment in hypovolemia
ringer’s solution
– used to determine the reflex of the frog’s muscle for acidic stimuli
1% hydrochloric acid
sed for osmotic and diffusion
2g NaCl crystals
used to sedate frogs using nasal inhalation
ether
read procedure
- Sedate the frog by nasal inhalation using ether or chloroform in cotton (additional option by pithing)
- Locate the frog’s thigh end leg, remove the skin with scissor then by using a scalpel, expose the frog’s thigh and leg, deflect the femoral muscles and locate the sciatic nerve (nerve extending from pelvic bone to the gastrocnemius muscle)
- Remove the femoral muscles and retaining its femur one, set apart the sciatic nerve carefully and cut it from the pelvic bone end. Carefully, lead the femur bone- sciatic nerve up to the gastrocnemius muscle, trace the gastrocnemius muscle that leads to the tendon of Achilles. Cut the tendon.
- This set-up m◦ust extract the femur bone, sciatic nerve and gastrocnemius muscle or the muscle-nerve set-up. Try to poke or pinch the nerve with glass rod and observe for muscle contraction (twitch), this will serve an exercise to ensure the fresh state of the nerve.
- The completely exercised muscle-nerve may now be suspended using femur clamp and tie the end Achilles tendon to the hook lever. Carefully rest the sciatic nerve on the horizontal fixed glass slide. Always moisten the nerve with Amphibian’s Ringer solution and Kymograph set-up.
- Using the diagram, set the kymograph drum, kymograph paper and key stimulators, battery for electrical supply, and each to the muscle-nerve set-up always check the Muscle-nerve to be moistened with Ringer’s solution. Perform the following stimulations and exercise.
- Note: Always allow the muscle-nerve to rest for 2 to 3 minutes after each test. Set the kymograph drum speed at medium pace and run the. Allow one (1) complete rotation for each kind of stimuli for Steps 1 to 4
Pinch or strike with a pithing needle or scalpel the free end of a nerve. Immediately release after a tracing is recorded. After five (5) seconds, repeat until a rotation is completed. Wash and supply with drops of Ringer’s solution
what kind of stimulus
mechanical
Soak the glass rod in a boiled water, then touch the free end of the nerve lightly with a warm glass rod. After tracing is recorded, remove the glass rod and touch again after a few seconds. Repeat until one rotation is completed. Wash and supply with drops of Ringer’s solution.
thermal stimulus
Place e few crystals of NaCl on the free end. After one rotation, immediately wash with Amphibian Ringers solution and then adjust the drum in order to record continuous twitching, if any, stop after one complete rotation. Wash and supply with drops of finger’s solution
osmotic stimulus
Place the stimulating electrode in a fixed position under the nerve. Set the potentiometer at 3 or 4, then press the key to apply a mild shock by using a single stimulation from the inductorium. Observe for a muscle twitch recording then, immediately turn off the stimulating apparatus onca a tracing is recorded. Repeat the single stimulation after five (5) seconds until one rotation is completed. Wash with Ringer’s solution
electrical stimulus
- Characteristics of stimulus: the drum should be kept stationary during stimulation such that any contraction of the muscle traces only a vertical line
After the tracing is properly recorded rotate the drum about 2 cm and wait for 30 seconds before another stimulus is applied
The stimuli will be elicited by the use of the inductorium and the strength of stimuli of current used will be based on the potentiometer reading.
+1
– stimuli are any sensory stimuli below an individual’s threshold
subliminal stmuli
- is defined as a stimulus that is presented below the level of conscious perception
liminal stimuli
is the smallest amount of stimulation or force that is needed to initiate a response
threshold stimulus
– start with this in the potentiometer
1
first visible contraction or tracing is recorded in the kymograph paper
threshold stimulation
is the strongest possible stimulus that occurs to produce the most muscle contraction.
maximal stimulus
the accumulating contractile force resulting from sequential activations applied to a muscle without sufficient interval to permit complete relaxation
summation
Achieved due to the current at 10mV difference, slightly below threshold so that no twitch is obtained (confirmed as subliminal simulation)
Then stimulation of the free end of the nerve ten to fifteen times at a rate of 2-3 seconds using the simple key and drum rotating at medium speed
summation
to check for its anesthetic effect, apply a pinch on the nerve. Once anesthesia has been attained, stimulate the nerves in a portions between the cotton soaked in ether and the gastrocnemius muscle.
ether
read afferent and efferent nerve fibers procedure
- Pin the sedated frog in a dissecting pan ends open the abdomen with a middle incision in the belly. Remove all the viscera to produce a spinal exposed animal. Also, remove the skin of the frog in both lower extremities.
- At the hip portion, locate the sacral plexus with the use of a glass slide and gently lift the three (3) roots of the sciatic nerve. Appy a loose ligature. Do the same procedure for the other sciatic nerve. Trace the length of the nerve to observe twitching muscle contraction) in the gastrocnemius
- Lift gently the roots of the sciatic nerve on the stimulating electrode. Make sure that no contact is made between the electrodes and the neighboring tissues.
- Use the inductorium to stimulate the left nerve for one second with a current enough to cause on the left gastrocnemius. Stimulate the nerve again with a current enough to cause on both gastrocnemius. Label the kymograph tracing and attach in the worksheet.
- . In the middle of the right thigh, securely tie separate ligatures about (5mm apart) on the sciatic nerve and make a clean cut between the two ligatures. Using the current known to cause contraction to both muscles, stimulate the proximal nerve ending going to the muscle. Label the kymograph tracing and attach in the worksheet.
+1
