Reflexes

Question 1

Reflexes traits

Answer 1

• automatic, preprogrammed responses to the Stimuli (rapid, predictable, involuntary)
• “one way street”
• inborn or learned (governed by the lower regions of the CNS (pupils dilating) or requires practice and repetition (walking, sports))
• involves both CNS and PNS
• can be somatic or automatic (visceral) (ex ) heart regulation, salivary secretion)
• occur over neural pathways: reflex arcs

Question 2

Reflex arcs

Answer 2

• (maintains homeostasis)
• have a minimum of five elements:
• receptor: reacts to stimulus
• sensory neuron: sends impulse to the CNS
• CNS integration centre: synapse or interneurons that connects the sensory neuron to motor neuron
• motor neuron: sends impulse to the effector
• effector; muscle or gland

Question 3

Reflex arc length

Answer 3

• simplest kind: monosynaptic (two neurons)
• ex) knee reflex
• though most are more complex, requiring more than two neuron reflex, requiring synapses between one or more interneurons in the CNS
• more synapses in the arc, slower the reflex because of the time it takes to diffuse
• ex) withdrawal reflex

Question 4

Spinal reflex

Answer 4

• many somatic reflexes are mediated by the spinal cord (can be present even if brain dead)
• brain still “advised” of spinal reflex activity, facilitates, inhibits, or adapts it

Question 5

Brain involvement reflexes

Answer 5

• some reflexes require brain involvement
• many different types of information have to be evaluated to get the correct response
• ex) pupil contraction and dilation in response to light