IX

Question 1

Where does the reflex arc start and end?

Answer 1

Starts at the sensory receptors and ends in the effector organ

Question 2

What are the major components of a reflex arc?

5

Answer 2

1 receptor (transducer)
2 afferent neuron and its axon (sensory nerve - input signal)
3 synapses in the CNS (central process unit)
4 efferent neurons and its axon (motor nerve - output signal)
5 target organ (effector organ)

Question 3

What happens if any component of the reflex arc is malfunctioning?

Answer 3

The expected reflex response does not occur

Question 4

Two different locations of receptor?

Answer 4

Proprioceptive and exteroceptive

Question 5

What are proprioceptive reflexes?

Answer 5

Spinal reflexes where the receptors are in the organ (muscle) that represents the effector response

Question 6

Are proprioceptive reflexes monosynaptic or polysynaptic

Answer 6

Monosynaptic (afferent nerve ends directly on the efferent nerve)

Question 7

How long does the proprioceptive response last?

Answer 7

No longer than the stimulus

Question 8

Does the proprioceptive stimulus cause fatigue?

Answer 8

No

Question 9

Knee jerk reflex
Stimulation
Muscle
Afferent and efferent nerve 
Segments of spinal cord
Normal reaction

Answer 9

Tapping patellar tendon
M. Quadriceps femoris
N. Femoralis
L4
The leg extends

Question 10

Ankle jerk reflex
Stimulation
Muscle
Afferent and efferent nerve 
Segments of spinal cord
Normal reaction

Answer 10

Tapping Achilles’ tendon 
M. Gastrocnemius, m. Soleus 
N. Tibialis
S1
Stretching ankle, plantar tendon

Question 11

Triceps reflex
Stimulation
Muscle
Afferent and efferent nerve 
Segments of spinal cord
Normal reaction

Answer 11

Tapping tricep tendon just above elbow
M. Triceps brachii 
N. Radialis 
C6-7
Stretching elbow

Question 12

Biceps reflex 
Stimulation
Muscle
Afferent and efferent nerve 
Segments of spinal cord
Normal reaction

Answer 12

Tapping the biceps tendon, above the elbow bend
M. Biceps brachii
N. Musculocutanous
C5-6
Flexion of elbow

Question 13

What is exteroceptive reflex?

Answer 13

Receptor located outside of effector organ (e.g. receptor in skin, effector is muscle)

Question 14

How does the stimulus reach the motor pathways?

Answer 14

Through several inhibitory or excitatory interneurons

Question 15

Is the exteroceptive reflect monosynaptic or polysynaptic?

Answer 15

Polysynaptic, long latency period

Question 16

How fast is the response, does the exteroceptive reflex fatigue?

Answer 16

Slow response, does fatigue

Question 17

The exteroceptive reflexes are mainly …?

Answer 17

Nociceptive (pain)

Question 18

Panniculus reflex
Stimulation
Muscle
Afferent and efferent nerve 
Segments of spinal cord
Normal reaction

Answer 18

Scratching skin in abd region
Skin muscles 
Nn. Cutanei trunci
C2-T1
Contraction of skin muscles

Question 19

Flexor reflex and crossed extensor reflex
Stimulation
Muscle
Afferent and efferent nerve 
Segments of spinal cord
Normal reaction

Answer 19

Scratching the pads
Flexors of ipsilateral, extensors of the contralateral legs
Sensor and motor neurons of the fingers
C5-T1
L5-S1
Bending fingers and the leg, extension of contralateral side

Question 20

Corneal reflex
Stimulation
Afferent and efferent nerve
Normal reaction

Answer 20

Touching the cornea
Aff N. Trigeminus
Eff N. Facialis
Blink the eye

Question 21

Menace reflex
Stimulation
Afferent and efferent nerve
Normal reaction

Answer 21

Moving hand abruptly toward the eye
Aff n. Opticus
Eff n. Oculomotorius
Blink eye, move head away

Question 22

Direct pupillary light reflex
Stimulation
Afferent and efferent nerve
Normal reaction

Answer 22

Shining a penlight into one of the eyes
Aff. N. Opticus
Eff. N. oculomotorius
Contraction of ipsilateral pupil

Question 23

Consensual (indirect) pupillary light reflex
Stimulation
Afferent and efferent nerve
Normal reaction

Answer 23

Shining a penlight into one of the eyes
Aff N. Opticus
Eff. N. Oculomotorius
Construction of contralateral pupil

Question 24

Auditory reflex
Stimulation
Afferent and efferent nerve
Normal reaction

Answer 24

Loud noise
Aff. N. Vestibulocochlearis
Eff. All head and neck motor nerves
Move head and eyes away

Question 25

What does muscle stretch activate?

Answer 25

Nuclear bag and nuclear chain receptors in the intrafusal muscle fibers

Question 26

What are muscle spindles?

Answer 26

Groups of intrafusal fibers and the nerves belonging to them, encapsulated

Question 27

What happens when the muscle spindle is stimulated (stretched)?

Answer 27

A sensory impulse is generated to the spinal cord via neurons fibers type Ia and II

Question 28

Neurons fibers type Ia and II make what type of connection with the alpha motor neurons?

Answer 28

Excitatory, monosynaptic connection

Question 29

What happens if the alpha motor neurons are activated?

Answer 29

Brief rapid contraction of the same muscle

Question 30

What is the potential difference in a neuronal resting cell between the IC and EC space?

Answer 30

-50 to -100 mV (resting potential)

Question 31

What happens if the cell is stimulated with impulses of low intensity?

Answer 31

Local depolarization

Question 32

What happens if the depolarization reaches the threshold level?

Answer 32

The voltage gated sodium channels open and an action potential is elicited and propagated

Question 33

What is the all or none law?

Answer 33

Once the threshold voltage is reached, the amplitude of the AP is constant, regardless of the stimulus intensity

Question 34

Phases of AP | 4

Answer 34

``` Depolarization (Na channels open for .5 sec) Overshoot (pos charged IC) Repolarization (potassium efflux) Post hyperpolarization (neg charged IC) ```

Question 35

What happens with the AP if there is stronger stimulus?

Answer 35

More frequent AP

Question 36

What happens with the AP if a stimuli of gradually increasing intensity is applied?

Answer 36

No AP even above threshold

Question 37

What is accommodation?

Answer 37

After Na-channels are opened by depol., they are inactivated

Question 38

What is accumulation?

Answer 38

High frequency sub-threshold stimuli can induce an AP

Question 39

What is rheobase?

Answer 39

The minimal stimulus intensity that just generates an AP after being applied for a very long time

Question 40

What is chronaxie?

Answer 40

Minimal duration necessary to elicit an AP if the stimulus strength is twice the rheobase

Question 41

What does the chronaxie give information about and what is it suitable for?

Answer 41

Strength and duration of stimulus, suitable for characterizing the function of excitable tissues

Question 42

Do different nerve fibers that make up a nerve have same or different threshold potentials?

Answer 42

Different

Question 43

CAP

Answer 43

Compound action potential

Question 44

First CAP wave: Increased CAP: Further increasing of CAP

Answer 44

1 stimulus intensity just exceeded threshold of sensitive fiber 2 intensity increased, CAP reaches a maximum 3 after max, the supramaximal stimulus intensity still doesn’t give further responses

Question 45

What happens if a nerve is stimulated with twin stimuli and the interval between the pulses decreases

Answer 45

The second stimulus will not elicit maximal CAP because more and more nerve cells in the nerve fibers will be in their refractory period

Question 46

What factor determines if we have monophasic or biphasic CAP?

Answer 46

Distance between electrodes

Question 47

Define local response

Answer 47

Decreasing magnitude of potential charge due to physical processes

Question 48

Name of fibers leading impulse from organ to spinal cord?

Answer 48

Neuron fibres type Ia and II

Question 49

Explain repolarization

Answer 49

Positive charge decreases inside the cell

Question 50

In which period do you have absolute refractory period?

Answer 50

Period before repolarization where the CAP disappears

Question 51

Frequency coding?

Answer 51

Stronger stimulus, more frequent AP

Question 52

Receptors in intrafusal muscle

Answer 52

Nuclear chain receptors and bag receptors

Question 53

Which channel opens during repolarization?

Answer 53

Potassium

Question 54

Give the most characteristic features of non-myelinated impulse transmission

Answer 54

AP propagates step by step, a channel activates immediately the adjacent one