Lab Ex 22

Components of the Reflex Arc

1. receptor 2. sensory neuron 3. integration center 4. motor neuron 5. effector

What division of the autonomic nervous system is responsible for 1. ciliospinal 2. pupillary light 3. salivary

1. sympathetic (pupil dilates), 2. parasympathetic (constricts pupil), 3. parasympathetic

What are the simple stretch reflexes?

Achilles and patellar

What is the purpose of the corneal reflex?

Keeps foreign objects out of the eye?

What nerve is carrying the afferent and efferent impulses in the patellar reflex?

Lateral Femoral

What happens in the Hering-Breur reflex and what organ is involved and receptors stimulated?

Lungs, pulmonary stretch, receptors present in smooth muscle of airways respond to excessive stretching of lungs during large aspirations

Does distraction effect strength of reflex?

No

Do stretch reflexes need a brain?

No they only need afferent, control center, motor fibers to by elicited

What is the purpose of the pupillary light reflex?

Protect retina and photoreceptors from too much light

What does the corneal reflex do?

Protects the eye from damage, will close and pull away to keep things out

What muscles contract in the patellar reflex?

Quadricep muscles

In the pupillary reflex what is the receptor, what contains the afferent fibers, what is responsible for efferent impulses, and what is the effector?

Receptor os the retina of the eye, the optic nerve contains afferent fibers, the oculomotor nerve is responsible for conducting efferent impulses and the smooth muscle of the iris is the effector

What happens in the defecation reflex and what organ and receptors are involved?

Rectum, stretch receptors, signal to brain that defecation is needed when rectum is full

What happens during the patellar reflex when the subject is grasping the lab table?

Reflex is more vigorous and shorter

What happens during the patellar reflex when the person is tired?

Response less vigorous because muscle system is worn out, but nervous system is still becoming more vigorous because impulses increase over time due to summation

What nervous system is responsible for dilation of the pupil's?

Sympathetic

What does the contralateral response in the pupillary reflex indicate?

The pathways are connected

What happens in the micturition reflex and what is the organ involved and receptors stimulated?

Urination, bladder is the organ, stretch receptors, the bladder stretched and detected by receptors which signal the sacral cord that urination is needed

What are the factors the determine the time required for reaction to a stimulus?

Velocity of nerve conduction, the number of neurons and synapses involved, and the speed of effector activation

What is the plantar reflex?

When the cutaneous receptors are stimulated in the sole of the foot that causes the toes to flex and move closer together

What happens during achilles reflex?

Whole leg jerks

What are the superficial cord reflexes?

abdominal, cremaster, and plantar

What is Babinski's sign?

abnormal response in which the toes flare and the big toe moves in an upward direction (normal in babies)

Autonomic reflexes

aka visceral- mediated through autonomic nervous system and we are usually unaware of them

What is the ciliospinal reflex?

another reflex activity involving the pupil (ciliary muscle relax and pull suspensory ligaments taut) (ciliary muscle contracts to leave the lens alone and achieve highest focusing power)

What is a contralateral response?

any reflex observed on one side of body when the other side has been stimulated (consensual response)

What is an ipsilateral response?

any reflex occurring on the same side stimulated (pupillary light response)

What does reflex testing do?

assess condition of the nervous system

What is the achilles reflex?

assesses the first two sacral segments of the spinal cord

What is function of gastrocnemius?

assists with stabilization

What happens in the carotid sinus and what organ is involved and types or receptors?

carotid artery, barrow receptors, localized dilation of internal carotid artery so controls the blood pressure

motor neuron?

conducts efferent impulses from the integration center to an effector organ

What is the crossed-extensor reflex?

consists of a flexor withdrawal reflex followed by extension of the opposite limb

Two somatic reflexes in which higher brain centers participate?

corneal and gag

What are Cranial Nerve Reflexes?

corneal and gag

Two cord mediated reflexes?

cross extensor, stretch, achilles

What do bad reflexes indicate?

distortion or pathology of nervous system

What happens when the oral mucosa on the uvula side is stroked? (uvula is the fleshy tab hanging from the roof of the mouth just above the root of the tongue)

each side of mucosa should rise to equal elevation

Three factors that modify reaction time to a stimulus?

fatigue, focus on something else, intoxication

3 neuron reflex arc is

flexor reflex

What are the effectors of the salivary reflex?

glands

What are basic reflexes?

inborn

Somatic reflexes

include all reflexes that involve stimulation of skeletal muscles by the somatic nervous system

Reciprocal inhibition

inhibition of those interneurons and the antagonist muscles during a stretch reflex causes antagonist muscle to relax so the stretched muscle isn't stopped from contracting

What is the purpose of the cross extensor reflex?

keeps yourself from danger of stimulus and keeps balance and body function in the rest of your body

What are the two types of pupillary reflexes?

light reflex and consensual reflex

polysynaptic

many synapses, involving participation of one or more interneurons in the reflex arc pathway

What is the corneal reflex?

mediated through the trigeminal nerve (cranial nerve V)

What happens when you increase the excitatory level and decrease inhibition

more likely to have a reflex

effector?

muscle fibers or glands, responds to efferent impulses characteristically (by contracting or secreting respectively)

What is the reflex arc for the patellar reflex?

muscle spindle, femoral nerve, spinal cord, motor neuron, quadricep muscle

What is the reflex arc for the achilles?

muscle spindle, sciatic nerve, sacral nerve, gastrocnemius

integration center?

one or more neurons in the CNS

monosynaptic

one synapse

Stretch reflexes

postural reflexes for posture, balance, and locomotion, initiated by tapping a tendon which stretches the muscle the tendon is attached too, this stimulates muscle spindles, reflex contraction of stretched muscle

What are learned or acquired reflexes?

practice and repitition

What are the autonomic reflexes?

pupillary, ciliospinal, and salivary

Reflex

rapid, predictable, involuntary motor responses to stimuli that are mediated over neural pathways called reflex arcs

What happens when you prick someone's finger with a pencil

reflex in both hand and the leg

spinal reflexes

reflexes that are initiated and completed at the spinal cord level occur without the involvement of higher brain centers (can work w/o a brain)

What are some jobs of the autonomic reflexes

regulate digestion, elimination, blood pressure, salivation, and sweating

What are superficial cord reflexes?

result from pain and temperature changes that are initiated by stimulation of receptors in the skin and mucosae, and depend on functional upper-motor pathways and on the cord-level reflex arc

if the response to a reflex involves a specific reflex arc then how is the response?

short

Receptor?

site of stimulus action

What muscle do autonomic reflexes activate?

smooth, cardiac, and glands

Spinal reflexes

stretch, cross-extensor, (withdrawal)

Types of somatic reflexes

stretch, cross-extensor, superficial cord, corneal, gag, patellar, achilles, abdominal, and plantar

What is the gag reflex?

tests the somatic motor responses of cranial nerve IX and X (glosspharyngal and vagus)

The more synapses there are in a reflex pathway =

the more time required to effect the reflex

Why do learned reflexes take longer?

they involve larger number of neural pathways and many types of higher intellectual activities (choice)

impulses relayed to higher brain centers because (via dorsal white columns)

to advise muscle length, speed of shortening, info needed to maintain muscle tone and posture

sensory neuron?

transmits afferent impulses to CNS