1. The Peripheral Nervous System and Reflex Activity: Part A13
The Peripheral Nervous System and Reflex Activity: Part A

2. Peripheral Nervous System (PNS)
All neural structures outside the brain
Sensory receptors
Peripheral nerves and associated ganglia
Motor endings

3. Central nervous system (CNS)
Peripheral nervous system (PNS)
Sensory (afferent)
division
Motor (efferent) division
Somatic nervous
system
Autonomic nervous
system (ANS)
Sympathetic
division
Parasympathetic
division
Figure 13.1

4. Sensory Receptors
Specialized to respond to changes in their environment (stimuli)
Activation results in graded potentials that trigger nerve impulses
Sensation (awareness of stimulus) and perception (interpretation of the meaning of the stimulus) occur in the brain

5. Classification of Receptors
Based on:
Stimulus type
Body Location
Structural complexity

6. Classification by Stimulus Type
Chemoreceptors—respond to chemicals (e.g., smell, taste, changes in blood chemistry)
Mechanoreceptors—respond to touch, pressure, vibration, stretch, and itch
Nociceptors—sensitive to pain-causing stimuli (e.g. extreme heat or cold, excessive pressure, inflammatory chemicals)
Photoreceptors—respond to light energy (e.g., retina)
Thermoreceptors—sensitive to changes in temperature

7. Classification by Location
Exteroceptors
Respond to stimuli arising outside the body
Receptors in the skin for touch, pressure, pain, and temperature
Most special sense organs
Interoceptors (visceroceptors)
Respond to stimuli arising in internal viscera and blood vessels
Sensitive to chemical changes, tissue stretch, and temperature changes
Proprioceptors
Respond to stretch in skeletal muscles, tendons, joints, ligaments, and connective tissue coverings of bones and muscles
Inform the brain of one’s movements

8. Classification by Structural Complexity
Complex receptors (special sense organs)
Vision, hearing, equilibrium, smell, and taste (Chapter 15)
Simple receptors for general senses:
Tactile sensations (touch, pressure, stretch, vibration), temperature, pain, and muscle sense
Unencapsulated (free) or encapsulated dendritic endings

9. Structure of a Nerve
Cordlike organ of the PNS
Bundle of myelinated and unmyelinated peripheral axons enclosed by connective tissue

10. Connective tissue coverings include:
Structure of a Nerve
Connective tissue coverings include:
Endoneurium—loose connective tissue that encloses axons and their myelin sheaths
Perineurium—coarse connective tissue that bundles fibers into fascicles
Epineurium—tough fibrous sheath around a nerve

11. Classification of Nerves
Most nerves are mixtures of afferent and efferent fibers and somatic and autonomic (visceral) fibers
Pure sensory (afferent) or motor (efferent) nerves are rare
Types of fibers in mixed nerves:
Somatic afferent and somatic efferent
Visceral afferent and visceral efferent
Peripheral nerves classified as cranial or spinal nerves

12. Twelve pairs of nerves associated with the brain
Cranial Nerves
Twelve pairs of nerves associated with the brain
Most are mixed in function; two pairs are purely sensory
Each nerve is identified by a number (I through XII) and a name
“On occasion, our trusty truck acts funny—very good vehicle anyhow”
On Old Olympus' Towering Top, A Fine Vocal German Viewed Some Hops

13. Hypoglossal nerve (XII)
Filaments of
olfactory
nerve (I)
Frontal lobe
Olfactory bulb
Olfactory tract
Optic nerve
(II)
Temporal lobe
Optic chiasma
Infundibulum
Optic tract
Facial
nerve (VII)
Oculomotor
nerve (III)
Vestibulo-
cochlear
nerve (VIII)
Trochlear
nerve (IV)
Trigeminal
nerve (V)
Glossopharyngeal
nerve (IX)
Abducens
nerve (VI)
Vagus nerve (X)
Cerebellum
Accessory nerve (XI)
Medulla
oblongata
Hypoglossal nerve (XII)
(a)
Figure 13.5 (a)

15. (One) smells first, olfactory.
(Two) optic for stuff we see.
(Three) oculomotor tie
(Four) with trochlear round the eye.
(Five) trigeminal the great.
(Six) abducens eyes rotate.
(Seven) facial faces near.
(Eight) vestibulocochlear.
(Nine) glossopharyngeal.
(Ten) vagus. lungs, guts, heart and all.
(Eleven) accessory shoulders reach.
(Twelve) hypoglossal tongue and speech.

16. a. Olfactory b. Optic c. Oculomotor d. Trochlear e. Trigeminal f
a. Olfactory b. Optic c. Oculomotor d. Trochlear e. Trigeminal f. Abducens g. Facial h. Vestibulocochlear i. Glossopharyngeal J. Vagus k. Spinal Accessory I. Hypoglossal

17. (XI) Spinal Accessory
(I) Olfactory
(III) Oculomotor
(X) Vagus
(VII) Facial
(V) Trigeminal
(VIII)Vestibulococchlear
glossopharyngeal (IX) and facial (VII)
(III) Oculomotor, (IV) Trochlear and (V) Trigeminal
(II) Optic
(I)Olfactory, (II) Optic, (VIII) vestibulocochlear

18. Afferent vs. Efferent D. Interneurons B. Motor (Efferent)
A. Sensory (Afferent)
C. Both

19. Delivers impulses from the CNS to muscles and glands
Motor Division
Delivers impulses from the CNS to muscles and glands
Somatic Nervous System –regulates processes under voluntary control
Autonomic Nervous System – regulates involuntary activities and is further divided into:
Sympathetic Nervous system – “fight or flight”
Parasympathetic –”Rest and Digest”

20. Reflex Arc
Reflexes - actions of the somatic nervous system that occur automatically

21. R-SIM Reflex arc pathway . . .
receptor neuron receives the stimuli S
sensory neuron passes the impulse on I
interneuron at the spinal cord processes M
motor neuron acts

22. The Autonomic Nervous System