Reflexes

Question 1

reflux

Answer 1

• Rapid automatic response to the stimuli
• Through spinal cord (without the involvement of brain)
  Examples:
  Blinking
  sneezing/coughing
  salivation

Question 2

reflex arc

Answer 2

*Neural pathway that mediates in a reflex action

• Sensory neurons pass through the spinal cord to activate spinal motor neurons without delay of steering signals through the brain

Question 3

components of reflex arc

Answer 3

1. Sensory receptor
2. Sensory nerve (afferent neuron)
3. Interneuron (synapse)
4. Motor nerve (efferent neuron)
5. Target organ (muscle or gland)

Question 4

sensory receptor

Answer 4

receives informations and generates impulses

Primary: neuron with specialized region for stimulus transduction

Secondary: non-neuronal cell specialized for stimulus transduction, stimulates neuronal cell through neurotransmitter

Question 5

on the basis of development

Answer 5

• Innate reflexes connection of the neurons that form during normal development, genetically determined
  Include: withdrawal from pain, blinking, and sucking
• Acquired reflexes are rapid, and automatic but are
  learned responses
  Include: salivation when smelling food

Question 6

motor responses

Answer 6

• Somatic reflexes: control activities of the muscular system
• Visceral reflexes: autonomic involuntary reflexes, control the actions of smooth and cardiac muscles and glands

Question 7

processing site

Answer 7

Spinal reflexes: control the activities of the muscular system

Cranial reflexes: processed in the brain

Question 8

complexity of the circuit

Answer 8

Monosynaptic reflexes: sensory neuron synapses directly with the motor neuron.
Little delay between sensory input and motor
output.

*Control the most rapid reflexes

Question 9

polysynaptic refelxes

Answer 9

• At least one neuron between sensory afferent and motor efferent
• Longer delay between stimulus and response
• Length of delay = # of synapses involved
• Can produce far more complicated responses that monosynaptic reflexes as the interneurons can control several muscle groups

Question 10

unconditioned reflexes

Answer 10

inborn reflex, inherited and shown from birth onward, and present in all individuals and animals

Example: withdrawal from pain

Question 11

conditioned reflexes

Answer 11

not inherited, learn by doing the same act several times

Example: salivation when smelling food

Question 12

muscle spindles

Answer 12

• Sensory receptors within the belly of a muscle
• Primarily detects change in the length of this muscle
• measure stretch of the muscle
• stimulate alpha motor neurons to contract and stretch

*Sensory receptors within the belly of a muscle
Primarily detects change in the length of this muscle

Question 13

Stretch reflex (myotatic reflex)

Answer 13

• extrafusal fibers
• intrafusal fibers
• golgi tendon organ

Question 14

extrafusal fibers vs intrafusal fibers

Answer 14

extrafusal fibers: regular contractile tissue, innervated by alpha motor neurons, stimulates contraction

intrafusal fibers: (sense organs within muscle fibers). Innervated by gamma motor neurons

Question 15

golgi tendon organ

Answer 15

senses stretch in tendons- feeds back on a alpha motor neurons (similar to stretch receptors but in the tendons)

*proprioceptor

Question 16

plantar reflex

Answer 16

causes a downward response (flexion)

Question 17

Babinski reflex

Answer 17

plantar reflex to upward response (extension)

Question 18

disease of the lower motor neurons

Answer 18

• paralysis paresis
• atrophy
• losses of sensory neurons

Question 19

paralysis paresis

Answer 19

message from the brain cannot reach the muscle

Question 20

atrophy

Answer 20

shrinking of skeletal muscle distal to the alpha motor neuron. Injury to nerves. Reduced frequency of muscle stimulation and results in reduced muscle protein synthesis

Question 21

disease of upper motor neurons

Answer 21

• Inappropriate movement: rigidity, seizures, circling
  gaits
• Retained by exaggerated segmental reflexes such as crossed extensor reflexes

Question 22

Which of the following statements are true?

a. Most reflexes travel only to the brain
b. Most reflexes travel only to the spinal cord
c. Most reflexes involve both the brain and spinal cord

Answer 22

b. most reflexes travel only to the spinal cord

Question 23

Which of the following is not a reflex

a. Salivation
b. Secretion of sweat
c. Flexion due to the needle pick
d. Blinking of eyes due to strong light

Answer 23

b. secretion of sweat

Question 24

The muscle spindle receptor is an encapsulated group of specialized (intrafusal) skeletal muscle fibers are supplied with:

a. Both motor and sensory innervation
b. Only motor
c. Only sensory
d. None

Answer 24

a. both motor and sensory innervation

Question 25

Which of these receptors detects an increase in tension in a muscle?

a. Golgi tendon organ
b. Muscle spindle
c. Both
d. none

Answer 25

b. muscle spindle