KISII UNIVERSITY

SCHOOL OF MEDICINE
DEPARTMENT OF MEDICAL PHYSIOLOGY
PRACTICAL: HUMAN REFLEXES
OBJECTIVES
1) To demonstrate stretch reflexes of the eye and tendon reflexes.
2) To observe the effects of mental activity simultaneously, muscular activity, and fatigue on strength reflexes
3) To determine the influence of conscious control on gag reflex.

Definition of terms:
1) Homeostasis: is the state of steady internal, physical, chemical, and social conditions maintained by living systems; the ability to maintain internal
stability in an organism in response to the environmental changes.
2) Positive feedback mechanism: It amplifies changes rather than reversing them; causes the output to vary even more in the direction of the initial
deviation. Examples include: Childbirth – stretching of uterine walls cause contractions that further stretch the walls; Lactation – the child feeding
stimulates milk production which causes further feeding and blood clotting.
3) Negative feedback mechanism: It is a type of self-regulating system that serves to reduce an excessive response and keep a variable within the normal
range. Examples include regulation of body temperature, blood sugar levels and reflexes
4) Reflex arc: It is a neural pathway that controls a reflex action. There are two types: Autonomic and somatic reflex arcs.
5) Somatic reflex arc: A type of reflex arc that involves the skeletal muscles; are unlearned muscle reflexes and are mediated by the brainstem
6) Autonomic reflex arc: Affects inner organs; are unconscious motor reflexes relayed from the organs and glands to the CNS.
7) Spinal reflex: include the stretch reflex, the Golgi tendon reflex, the crossed extensor reflex, and the withdrawal reflex. Spinal reflexes are rapid,
involuntary, and predictable responses to specific stimuli that are mediated by the spinal cord without requiring input from the brain. They occur as
automatic, involuntary responses to stimuli generated within the nervous system.
8) Conditional reflex: A learned response performed by a human or other animal to a signal that was previously associated with an event of consequence
for that human or animal.
9) Stretch reflex: myotatic reflex/deep tendon reflexes or "muscle stretch reflex", is a muscle contraction in response to stretching a muscle or tendon.
10) Ipsilateral reflex: refers to structures on the same side of the body or brain (left or right)
11) Contralateral reflex: refers to structures on opposite sides of the body (left and right)
12) Consensual reflex: It is any reflex observed on one side of the body when the other side has been stimulated. The change in pupil size in the eye
opposite to the eye to which the light is directed (e.g., if the light is shone in the right eye, the left pupil also constricts consensually).

REFLEXES
A reflex is a protective, involuntary and nearly instantaneous movement in response to a stimulus. It is an automatic response to a
stimulus that does not receive or need conscious thought as it occurs through a reflex arc. Reflex arcs act on an impulse before that impulse
reaches the brain. A reflex is a sequence of events initiated by a sensory input and executed by a muscle or gland. Reflexes therefore are simplest
functional responses of the nervous system. Reflex actions are purposeful, for example, the withdrawal of an appendage from painful stimuli and
the movement that allow balance to be maintained. Reflexes contribute to the maintenance of homeostasis.
In negative feedback mechanism, a controlled variable is regulated at an appropriate value. The controlled variable is monitored by
receptors or sensors that pass the information to an integrator. Diversion of the variable from its ideal level, or set point, results in the activation
of effectors that oppose the departure from the set point. A reflex is a negative feedback circuit in which a detection system is linked to a
response system.
Reflex arcs can be:
I. Monosynaptic i.e., contain only two neurons, a sensory and a motor neuron. Examples of monosynaptic reflex arcs in humans include
the patellar reflex and the Achilles reflex.
II. Polysynaptic i.e., multiple interneurons (also called relay neurons) that interface between the sensory and motor neurons in the reflex
pathway.
Reflexes are the body’s intrinsic stimulus-response systems for maintaining homeostasis, and when performed and interpreted correctly are the
most objective evidence within the neurological screen to localize the lesion to specific structures within the nervous system.
A reflex action usually consists of:
a) An afferent or sensory component.
b) An integrator component.
c) An efferent component.

DIAGRAM 1: REFLEX ARC COMPONENTS. DIAGRAM 2: REFLEX ARC COMPONENTS

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A reflex arc therefore will consist of five components:
1) A receptor: to which the stimulus is applied e.g., the skin
2) Afferent pathway: which, in the simplest of reflexes consists of one sensory neuron in the peripheral nervous system (PNS) carrying the impulses
generated by the stimulus acting on the receptor, to the CNS. However, in the more complex reflexes, ascending tracts may form part of the “afferent”
pathway.
3) The central analyzer: which, in the simplest (monosynaptic) reflex, this may consist of the synapse between the afferent and the efferent neurons in
the CNS. In the more complex reflexes (polysynaptic), the central analyzer, usually called the “center” is made up of complex ones, other parts of the
CNS e.g., cerebellum, basal ganglia, etc. may be involved.
4) The efferent pathway: in simple reflexes consists of Somatic neurons which innervate skeletal muscles, while Autonomic neurons which innervate
skin, the heart blood vessels internal organs, and glands; conducting the impulses from CNS to the effector organ. In more complex reflexes, however,
the descending tracts may form part of the “efferent pathway”.
5) The effector or motor organ: is the structure in the body which “exteriorizes” the response; consists of neurons that transmit impulse peripherally and
an effect that responds to the nerve impulses i.e., often a muscle fiber or a gland.

REFLEX TESTING:
Reflex testing, is simply applying the adequate stimulus to the receptors, and observing the expected response at the effector organ.
NOTE:
1) The muscle group to be tested must be in a neutral position (i.e., neither stretched nor contracted).
2) The tendon attached to the muscle(s) which is/are to be tested must be clearly identified. Place the extremity in a positioned that allows the tendon to be
easily struck with the reflex hammer.
3) To easily locate the tendon, ask the patient to contract the muscle to which it is attached. When the muscle shortens, you should be able to both see and
feel the cord like tendon, confirming its precise location.
4) Strike the tendon with a single, brisk, stroke. You should not elicit pain.
If the expected response is observed, it may then be reasonably assumed that the whole reflex arc is intact. If, on the other hand, the responses are abnormal, e.g.,
stronger than expected (exaggerated) weak than expected or even completely unobservable it may be reasonably assumed that some part of the arc is not
functioning normally.

INTERPRETETION OF RESULTS:
When attempting to interpret results from reflex testing, the following should be borne in mind.
1) This is only a sampling method whose validity will depend not on the number of reflex arcs tested, but also on how well distributed the centers are
along the brain stem and spinal cord.
2) Any abnormal reflexes observed may be abnormal not necessarily because of the neural parts of the arcs but also possibly because of the non- neural
parts of the arcs, such as the muscles which in most cases form the effector organs. Thus, which part of the arc is abnormal should be established before
any conclusions are drawn. It thus becomes imperative for the examiner to know all the parts of the reflex arcs for the reflexes he/she uses

This grading system is rather subjective:

0: No evidence of contraction
1+: Decreased, but still present (hypo-reflexic). Hyporeflexia is generally associated with a lower motor neuron deficit.
2+: Normal
3+: Super-normal (hyper-reflexic) Hyperreflexia is often attributed to upper motor neuron lesions e.g., Multiple sclerosis
4+: Clonus: Repetitive shortening of the muscle after a single stimulation. Involuntary and rhythmic muscle contractions caused by a permanent lesion in
descending motor neurons.

The brain is not required for spinal reflex to occur; however, cerebral activity frequently alters spinal reflex action in humans by either facilitating or inhibiting a
reflex. Some of the reflexes require the presence of functional brain tissue if they are to occur. The changes to the size of the pupils of the eyes in response to light
are in this category.
A conditioned reflex, also called an acquired reflex, is an automatic response to a stimulus that differs from that initially causing the response, but that has become
associated with it by repetition, in a process known as classical conditioning. It requires activity of the brain. Salivation is one such conditioned reflex; it occurs
only when a person is conscious of the presence of food or when one imagines food.

CLASSIFICATION OF REFLEXES
There are three types, Superficial, Deep tendon and Visceral reflexes used in assessing the integrity of the nervous system. Where abnormalities are suspected,
then Pathological reflexes may be used to provide some confirmatory evidence.
1) Superficial reflexes: they are revocable by stimulating receptors which are found in the skin or mucous membranes. Generally, these have a
complex pathway in the CNS. Such that damage to the upper motor neurons (descending tracts) may cause the response to be abnormal. This makes
them difficult to interpret when they are abnormal. However, abnormal superficial reflexes become more important when associated with exaggerated
deep reflexes and/or positive pathological ones. Examples include:
 Skin reflexes: elicited by stroking the skin. Plantar reflex (Babinski reflex), Gluteal reflex and anal reflex.
 Mucous Membrane Reflexes: elicited by stroking the mucous membranes. Corneal reflex, Gag reflex and Sneeze reflex.
2) Deep Tendon reflexes: Generally, these involve skeletal muscles. They are evoked by stimulating the muscle spindle. This is done as a result of
stretching the muscle by striking its tendon. The response, via a monosynaptic reflex, is a contraction of the muscle to oppose the stretch. These provide
the simplest and fastest types of reflexes, needing only a patellar hammer to evoke them. However, it is to be noted that these are normally under partial
inhibition by the higher centers. Concurrent engagement of the UMN mechanisms may disinhibit the reflex mechanism making the response stronger.
Damage to the UMN may have a similar effect, leading to exaggerated responses or even to muscular rigidity. Exaggerated deep reflexes also occur in
strychnine poisoning and in some functional disorders. On the other hand, lower motor neuron (LMN) lesions involving afferent, center and/ or
efferent, lesions of the effector organ may make the response diminish or totally un evocable. This may also happen in disease involving ascending
tracts, such as posterior columns of the spinal cord, or some centers receiving the feedback sensory information, such as the cerebellum. Examples
include: Biceps reflex, triceps reflex, knee jerk reflex and ankle jerk reflex.
3) Visceral reflexes: involve a glandular or non-skeletal muscular response carried out in internal organs such as the heart, blood vessels, or structures of
the GI tract. They utilize neurons of the autonomic nervous system to elicit their actions. Where the ANS is not involved, a deep tissue is to evoke the
response.
4) Pathologic reflexes are the reflexes seen in healthy newborns but not in healthy adults (eg, Babinski, Chaddock, Oppenheim, snout, rooting, grasp) are
reversions to primitive responses and indicate loss of cortical inhibition. Babinski, Chaddock, and Oppenheim reflexes all evaluate the plantar response.
The normal reflex response is flexion of the great toe.

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DIAGRAM 3: JENDRASSIK MANEUVER

Jendrassik maneuver is a medical maneuver wherein the patient clenches the teeth, flexes both sets of
fingers into a hook-like form, and interlocks those sets of fingers together. It is used to distract the patient. It
can be used to augment hypoactive reflexes i.e., the patient locks hands together and pulls vigorously apart as
a tendon in the lower extremity is tapped or pushes the knees together against each other, while the upper limb
tendon is tested. The jendrassik maneuver may exaggerate spinal reflexes such as the patellar reflex by
reducing activity in normal brain stem descending inhibitory pathways that control spinal reflex neurons; a
reduction in inhibition at the spinal level may lead to exaggerated reflex responses.

PURPOSE OF TESTING FOR SIMPLE REFLEXES:

 Sensory testing e.g., touch, pain, vision, hearing employs very complex pathways. Interpretation of such tests is simply limited to the specific aspect of
the sensation being tested for. To find out whether areas of the nervous system, particularly the CNS, especially the brainstem and spinal cord, are
normal reflex
 The reflex exam is fundamental to the neurological exam and important to locating upper versus lower motor neuron lesions.

ACTIVITY 1:
TESTING FOR SIMPLE STRETCH REFLEXES/MYOTATIC OR DEEP TENDON REFLEXES
Stretch reflexes to be tested include:
I. Biceps reflex
II. Triceps reflex
III. Patella reflex (knee jerk reflex)
IV. Ankle reflex
Stretch reflexes (also termed myotatic or deep tendon reflexes).
The receptors for stretch reflexes are called muscle stretch receptors or myotatic organs. They are embedded among the muscle fibers of most skeletal
muscle. When stretching a muscle, its stretch reflexes are monosynaptic, i.e. the afferent neuron synapse directly on the efferent neuron, without an intermediate
association neuron.
The patella reflex is an example of a stretch reflex. It can be initiated by tapping the tendon below the patellar, or kneecap. The stretching of the
extensor muscles to which the tendon is attached results in their reflex contraction and an extension (increasing the angle of the joint) of the low leg. The
stimulus you will use to elicit patellar reflex, (a tap on the knee) is an artificial means of stimulating a reflex response. The normal function of the stretch reflex is
to oppose involuntary stretching of muscles, making it possible for the body to be held in an erect position and to resist unexpected changes of position. The patella
is attached to the large muscle of the upper leg (quadriceps femoris). Contraction of this muscle extends the leg. When we stand up the quadriceps femoris is
contracted and must generate sufficient tension to support the weight of the body. The stretching opposes this buckling.
The ankle reflex also known as Achilles reflex is also an example of a stretch reflex. It occurs when the Achilles tendon is tapped while the foot is
dorsiflexed. It tests the function of the gastrocnemius muscle and the nerve that supplies it. The expected result would be the jerking of the foot towards its plantar
surface.
The force of a reflex response can be altered if other muscular activity occurs simultaneously. The additional muscular activity reduces the
resistance of synapses in reflex arcs in other parts of the body. Mental activity can also influence the expression of reflex activity, in part, by increasing
muscle tone on the other hand, fatigue decreases muscle tone.
Not all individuals have reflex responses that are equally forceful. It is vital, however, that in an individual the reflexes on the two sides of the body be
essentially of the same magnitude. A difference in the response on the two sides can indicate an abnormality in the nervous system.

DIAGRAM 4: TENDON/PATELLAR HAMMER DIAGRAM 5: DORSIFLEXION AND PLANTAFLEXION OF FOOT

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 The Biceps reflex test: the test activates the stretch receptors inside the biceps brachii muscle which communicates mainly with the C5 spinal nerve
and partially with the C6 spinal nerve to induce a reflex contraction of the biceps muscle and jerk of the forearm.
The Triceps reflex test: is a reflex that elicits involuntary contraction of the triceps brachii muscle. It is sensed and transmitted by the radial nerve.
The reflex is tested as part of the neurological examination to assess the sensory and motor pathways within the C7 and C8 spinal nerves. The test can be
performed by tapping the triceps tendon with the sharp end of a reflex hammer while the forearm is hanging loose at a right angle to the arm. A sudden
contraction of the triceps muscle causes extension and indicates a normal reflex.

REQUIREMENT:
1. Tendon hammer/ patella hammer/reflex hammer

PROCEDURE
PART 1
BICEPS REFLEX
1) Subject: Sit at a table or desk. The elbow should be bent and the arm completely relaxed, resting either on your lap or on the examiner’s arm.
2) Examiner: Gently press the biceps tendon in the antecubital fossa with your thumb (or forefinger), and strike your thumb with the reflex hammer.
Note: you should be able to feel the thick tendon with your thumb.
3) Examiner: Observe the biceps muscle for signs of movement. Ask the subject to describe any sensations felt.
Note: The muscle contraction may not be strong enough to cause arm movements

TABLE 1:
ARM TESTED RESPONSE
SUBJECT 1 SUBJECT 2
LEFT ARM
RIGHT ARM

PART 2
TRICEPS REFLEX
1) Raise and support the subject’s arm so that the elbow is at shoulder height. The arm should be completely relaxed. Alternatively, have the subject place
their hand on their hip. Using this position, may be easier to illicit a reflex but it would not be possible for the arm to actually move.
2) Strike the triceps tendon about 5cm above the elbow. If there is no response, repeat this procedure, striking to either side of the original point.
3) Observe the triceps muscle for signs of movement. Ask the subject to describe any sensations felt.
Note: the muscle contractions may not be strong enough to cause arm movements.

TABLE 2:
ARM TESTED RESPONSE
SUBJECT 1 SUBJECT 2
LEFT ARM
RIGHT ARM

PART 3
PATELLA REFLEX
1) Subject: Sit on a stool or table with both legs hanging freely. The thigh muscles should be relaxed.
2) Examiner: Using broad end of a patellar hammer, strike the patellar tendon, just below the patellar (knee cap). Observe the thigh muscle and record the
action (if any) of the lower leg. Describe the subject’s responses in the table.
3) Examiner: Test the other leg in the same way and enter your results in the table.
4) Examiner: Write down an additional problem consisting of ten numbers at least three digits each. Let the subject sit down in a position that allows the
patellar reflex to be checked. Check the patellar reflex of the subject (normal) once or twice, then give the subject the prepared problem and instruct
him/her to do it in the shortest time possible without the use of a pencil or pen (or calculator). While the subject is concentrating on the problem, check
his/her patellar reflexes. Describe them in the table.
5) Subject: Once again assume a position in which the patellar reflexes can be checked.
6) Examiner: Test the patellar reflex. Then instruct the subject to clasp his/ her hands together and hold them tightly clasped while contracting the muscle
of the arms as if to pull the hands apart- Jendrassik maneuver. While the subject is engaged in this muscular activity, check the patellar reflexes. Enter
your results in the table.
7) Subject: Run up and down a flight of stairs until you feel quite tired. Then sit down as before.
8) Examiner: Check the subjects patellar reflexes immediately after the subject sits down, and compare these to patellar reflexes observed earlier.

TABLE 3:
NB: Magnitude of response - use Weak, Moderate, or Strong to describe the response the subject.

THE PATELLAR REFLEX.

Conditions under which patellar reflex MAGNITUDE OF RESPONSE

was tested.
SUBJECT 1 SUBJECT 2

NORMAL

Left leg

Right leg

DURING CONCENTRATION

Left leg

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 Right leg

DURING JENDRASSIK MANEUVER

Left leg

Right leg

AFTER STRENUOUS ACTIVITY

Left leg

Right leg

PART 4
ANKLE REFLEX
1) Subject: sits on a chair and hangs his/her legs or rather dangle their feet.
2) Examiner: dorsiflex subject’s foot with one hand so as to stretch the Achilles tendon. Using the other hand, strike sharply on the posterior surface
targeting the Achilles tendon. Record your observations.

TABLE 4:
FOOT TESTED RESPONSE
SUBJECT 1 SUBJECT 2
RIGHT FOOT
LEFT FOOT

PART 5
PLANTAR REFLEX (BABINSKI REFLEX)

Plantar reflex is a reflex elicited when the sole of the foot is stimulated with a blunt instrument. The
Babinski reflex occurs after the sole of the foot has been firmly stroked. The big toe then moves upward
or toward the top surface of the foot. The other toes fan out.
The normal response is flexion (curling) of the toes and plantar flexion of the foot. If the toes spread
apart and dorsiflexion of the great toe occurs, the reflex is the abnormal Babinski reflex response (normal
in infants until the nerve fibers have completed myelinization). If the Babinski reflex occurs later in life,
it may indicate damage to the corticospinal tract of the CNS.
Babinski reflex is one of the normal reflexes in infants and in children up to 2 years old. It may disappear
as early as 12 months. In adults, this reflex is not normal and often indicates a problem with the brain or
spinal cord.

1. Subject: Have your partner remove a shoe and sock and lie supine with the lateral surface of the foot resting on the table.
2. Examiner: Draw the blunt metal tip of the rubber hammer/key applying firm pressure over the sole of foot from the heel to the base of the large toe.

TABLE 5:
FOOT TESTED RESPONSE
SUBJECT 1 SUBJECT 2
RIGHT FOOT
LEFT FOOT

ACTIVITY 2:
TESTING FOR EYE REFLEXES
The reflexes of the eye are a series of automatic changes in your eyes that help you see and protect your eyeballs from damage. They’re involuntary
movements — which means you can’t control them and don’t have to think about them. Eye reflexes protect your eyeballs and adjust your eyes to different
lighting conditions. They ensure there are no gaps in your vision, even if you move your eyes quickly or light changes suddenly. Some reflexes of the eye make
your eyes move or change as reactions to things going on around you.
1) PUPILLARY REFLEX
The pupil is the black center of your eye. Your pupils change in size to control how much light enters your eye. Muscles in your iris control the size of
your pupil. Pupillary reflexes make your pupil change size automatically in different amounts of light. They maintain vision in different conditions by changing
how much light enters your eyes and hits your retinas. On the pupillary reflex, the effectors are smooth muscle of the iris, which is innervated by both the
sympathetic and parasympathetic branches of the autonomic system. The size of the pupil changes in response to changes in input from either branch.
Parasympathetic input constricts the pupil while sympathetic input dilates it. The pupillary reflex opposes changes in the intensity of light reaching the retina. In
bright light, the pupils constrict, and dim light it dilates.
Consensual reflex: a reflex such as patella reflex, in which response is seen on the same side of the body of which the stimulus was applied, is said to
be ipsilateral. A reflex action seen on the side of the body opposite to the side stimulated is a contralateral reflex. Stimulation of one eye by light normally results
to both ipsilateral and contralateral reflexes. The constriction of the contralateral pupil is called consensual reflex. This reflex is lost in some conditions in which
information transfer from one side of the brain to the other is impaired

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Pupillary reflexes include:
 The pupillary light reflex: The pupillary light reflex makes your pupils shrink (contract) in bright light. Muscles in your irises squeeze tighter and
make your pupils smaller when bright light hits your eyes.
 The pupillary dark reflex: The pupillary dark reflex makes your pupils get bigger (dilate) when you enter a dark space. Your irises relax and open to
let more light into your eyes.
 The ciliospinal reflex: It is a reflex which changes the size of the pupil. It can be evoked by stimulating the skin on the back of the neck. Stimulating
the back of the neck increases the number of sympathetic nerve impulses to muscles that dilate the iris. The ciliospinal reflex makes your pupils dilate if
something hits your face or neck.

2) CORNEAL REFLEXES
The cornea is the clear window on the front of your eye. Together with the sclera (white of your eye), the cornea helps protect your eye. There are two corneal
reflexes:
 The blink reflex: an automatic response that makes you blink when something touches your cornea.
 The tear reflex (lacrimatory reflex): The tear reflex is also triggered by something touching your eye. It makes your tear system flood your eye with
fresh tears to wash away anything that’s stuck in your eye.

REQUIREMENTS:
1. Light torch

PROCEDURE
PART A
PUPILLARY REFLEX
1) Subject: Stand in a place where the lighting is relatively dim, away from the window or lamp.
2) Examiner: Note the size of each pupil of each eye and enter this value in the table.
3) Examiner: Shine a light into the subject’s eye. Record the change in diameter of each pupil in the table.

TABLE 6
PUPILLARY RESPONSE

EXPERIMENTAL CONDITIONS CHANGE IN PUPIL DIAMETER

SUBJECT 1 SUBJECT 2
Dim light: Left eye
Dim light: Right eye
Bright light: Left eye
Bright light: Right eye

PART B
CONSENSUAL REFLEX
1) Subject: Stand in a place where light is not shining directly into your eyes.
2) Examiner: Note the size of the subject’s pupil. Instruct the subject to hold a hand vertically between the two eyes (touching the nose and forehead).
Shine a torch into the subjects left eye. The hand should prevent the light from striking the right eye directly. Record your results in the table.

TABLE 7
CONSENSUAL RESPONSE

EXPERIMENTAL CONDITIONS CHANGE IN PUPIL DIAMETER

Left eye Right eye
Light not shining directly in eyes

Light shining only in Left eye

PART C
CILIOSPINAL REFLEX
1) Subject: Standing in a place where light is not shinning directly into his/her eyes
2) Examiner: While observing the subject’s pupil, lightly pinch or scratch the back of his/her neck. Record the observations in the table

TABLE 8
CILIOSPINAL REPONSE
EYE SUBJECT 1 SUBJECT 2
LEFT EYE
RIGHT EYE

ACTIVITY 3:
A. SWALLOWING REFLEX
Swallowing, or deglutition, is a complex reflex mechanism by which food is pushed from the oral cavity into the esophagus and then pushed to the stomach.
This movement of food from the oral cavity on to the esophagus and stomach by pushing is called propulsion, and it is an important part of the digestive process.
The function of each structure involved in the swallow summarizes into two main themes: propulsion of the bolus toward the stomach and protection of the airway

REQUIREMENT
1. Drinking water in a glass

PROCEDURE:
1) Swallow the saliva in your mouth.
2) Attempt to swallow again immediately after the first swallow. Record what happens.

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 3) If you were unable to swallow the second time, this might because swallowing is not possible when there is no saliva in the mouth or because the
swallowing act cannot be performed in a rapid succession.
4) To test the second possibility, try rapid succession by rapidly drinking a glass of water. Describe what happens.

TABLE 8: USE “YES” OR “NO” TO DESCRIBE ABILIY TO SWALLOW

ABILITY TO SWALLOW
EXPERIMENTAL CONDITIONS SUBJECT 1 SUBJECT 2
Start of experiment
Immediately after first swallow
While drinking water

B. GAG REFLEX (PALATAL REFLEX)

The gag reflex is a natural somatic response in which the body attempts to eliminate unwanted agents or foreign objects from the oral cavity through muscle
contraction at the base of the tongue and the pharyngeal wall. It is also called the pharyngeal reflex, is a contraction of the throat that happens when something
touches the roof of your mouth, the back of your tongue or throat, or the area around your tonsils. This reflexive action helps to prevent choking and keeps us from
swallowing potentially harmful substances.

REQUIREMENT
1. Tongue depressors

PROCEDURE:
1) Touch the soft palate or pharyngeal wall with tongue depressor. Record what happens.
2) Repeat step 1 while consciously trying to suppress the reflex response. Record your results.

TABLE 9
RESPONSE
EXPERIMENTAL CONDITIONS SUBJECT 1 SUBJECT 2
Soft palate touched with tongue depressor

Soft palate touched while attempting to

suppress reflex

ANSWER THE FOLLOWING QUESTIONS:

1) What are the parts of a reflex arc?

2) a) When the subject was concentrating on an arithmetic problem, was the patellar reflex altered.?
b) What influence does cerebral activity has on spinal reflexes?
3) Give receptors and the effector(s) for each of the reflexes listed below.
I. Patellar reflex
II. Ankle reflex
III. Pupillary reflex
IV. Ciliospinal reflex
V. Palatal reflex.
4) What is the function or adaptive advantage of each of the reflexes listed below?
5) Give one example of an ipsilateral response and one example of a contralateral response.
6) What type of innervation to the smooth muscles of the eye causes constrictions of the iris?
7) A) Describe the process by which conditional response are created.
B) List some conditioned reflexes you have experienced.
8) Discuss the relationship between reflexes and homeostasis.
9) How important is the ciliospinal reflex?
10) Describe the relevance of cerebral activity in spinal reflexes
11) List the types of reflexes and give examples of each.
12) Classify the following reflexes
 You take up a stone and a dog ran away.
 Eye closed when anything enters into it.
 You move your hand when somebody pierces you with a needle.
 Movement of digestive food in the alimentary canal.

COMPILED BY IRENE VUREMY

LABORATORY TECHNOLOGIST-MEDICAL PHYSIOLOGY

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