CAS BI 315 Chapter Notes - Chapter 4: Quadriceps Femoris Muscle, Ciliary Muscle, Rectus Femoris Muscle
1 Jul 2018
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Lab 4: Somatic Sensations and Reflex Functions of the Nervous System
I. Sensory receptors
A. Peripheral terminals = dendrites
B. Sensory neuron = afferent
C. Exteroreceptors: respond to stimuli from external environment
C.1. Photoreceptors: bright light
C.2. *Mechanoreceptors: fluid displacements due to air vibrations
(cochlea) or rotational & gravitational movements (vestibular apparatus)
C.3. Somatic: touch and pressure (skin)
C.4. *Chemoreceptors: process taste and smell
D. Interoreceptors: respond to stimuli inside body
D.1. *Mechanoreceptors: distention if GI wall (visceral sensations)
D.2. *Chemoreceptors: changes in pH
D.3. Baroreceptors: BP (in RA, aortic arch, and carotid sinus
E. Proprioreceptors: movement and position of head and body
* = categorized as both exteroreceptors and interoreceptors! (mechanoreceptors &
chemoreceptors)
F. Continuous stimulus of constant strength applied to receptor= decrease in
response over time = ADAPTATION
G. Receptor becomes unresponsive to the same stimulus type and magnitude
H. Sensory Unit = 1 sensory neuron and all the receptors in innervates
I. Receptive field= the area these receptors are distributed on surface of body
J. PRECISION/ ACUITY depend on:
J.1.Size of receptive field (- correlation to acuity)
J.2.# of receptive fields (+ correlation)
J.3.density/overlap of sensory units (+ correlation)
J.4.Density of receptors within receptive field (+ correlation)
K. All sensory inputs result in same afferent AP, but it is where the integrating
center is that determines what the perception is
II. Reflexes
A. Sensory receptor -> neural conducting pathway -> effector -> response
B. Reflexes have far fewer synapses compared to learned responses
C. Nociceptive withdrawal reflex= pain from fire/heat, immediate withdrawal of finger
from heat (no higher brain required, so will function in animals that are
decapitated → BROOOOOOO, really? YA BRO SO SICK)
D. Eye & vestibular reflexes = lower brain integrating center
E. Learned responses = higher brain
F. Patellar reflex (patellar tendon)
F.1. Higher brain INHIBITS patellar reflex
F.2. Injury ABOVE pathway= exaggerated response bc less inhibitory
effect (we test the integrity of the central pathways in this lab)
F.3. Injury in PNS pathway = less reflex response (we test the integrity
of the reflex pathway in this lab)
F.4. We (dem boyz) are testing the extent and location of a spinal cord
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Lab 4: somatic sensations and reflex functions of the nervous system. Sensory receptors: peripheral terminals = dendrites, sensory neuron = afferent, exteroreceptors: respond to stimuli from external environment. *mechanoreceptors: fluid displacements due to air vibrations (cochlea) or rotational & gravitational movements (vestibular apparatus) Baroreceptors: bp (in ra, aortic arch, and carotid sinus: proprioreceptors: movement and position of head and body. J. 1. size of receptive field (- correlation to acuity) J. 4. density of receptors within receptive field (+ correlation: all sensory inputs result in same afferent ap, but it is where the integrating center is that determines what the perception is. Ya bro so sick: eye & vestibular reflexes = lower brain integrating center, learned responses = higher brain, patellar reflex (patellar tendon) Injury above pathway= exaggerated response bc less inhibitory effect (we test the integrity of the central pathways in this lab) Injury in pns pathway = less reflex response (we test the integrity of the reflex pathway in this lab)
