1. The Nervous System

2. The Reflex Arc
Reflex—rapid, predictable, and involuntary response to a stimulus
Occurs over pathways called reflex arcs
Reflex arc—direct route from a sensory neuron, to an interneuron, to an effector

3. The Reflex Arc Stimulus at distal end of neuron Skin Spinal cord
(in cross section)
Interneuron
Receptor
Effector
Sensory neuron
Motor neuron
Integration center
(a)

4. Simple Reflex Arc
Sensory receptors (stretch receptors in the quadriceps muscle)
Sensory (afferent) neuron
Sensory receptors (pain receptors in the skin)
Spinal cord
Sensory (afferent) neuron
Synapse in ventral horn gray matter
Inter- neuron
Motor (efferent) neuron
Motor (efferent) neuron
Effector (quadriceps muscle of thigh)
Effector (biceps brachii muscle)
(b)
(c)

5. Types of Reflexes and Regulation
Somatic reflexes

6. Types of Reflexes and Regulation
Autonomic reflexes

7. Types of Reflexes and Regulation
Patellar, or knee-jerk, reflex is an example of a two-neuron reflex arc

8. Central Nervous System (CNS)
Ventricles

9. Cerebrum
Figure 7.14

10. Layers of the cerebrum Corpus callosum – Gray matter— White matter—
Basal nuclei-

11. White Matter

14. Cerebrum

15. Diencephalon
Figure 7.12b

17. Diencephalon (Interbrain)
On top of the brain stem
Enclosed by the cerebral hemispheres
Made of three parts:

19. Regions of the Brain: Diencephalon
Figure 7.16

20. Diencephalon
Thalamus
The relay station for sensory impulses
Crude:

21. Diencephalon Hypothalamus Under the thalamus
Important autonomic nervous system center

22. Diencephalon
Hypothalamus (continued)

23. Diencephalon
Epithalamus
Houses the pineal body (an endocrine gland)

24. Brain Stem
Attaches to the spinal cord Parts of the brain stem:

26. Brain Stem
Figure 7.16a

27. Brain Stem Midbrain Mostly composed of tracts of nerve fibers
Has two bulging fiber tracts— cerebral peduncles

28. Brain Stem Pons The bulging center part of the brain stem
Mostly composed of fiber tracts

29. Brain Stem Medulla Oblongata
The lowest part of the brain stem - Merges into the spinal cord
Contains important control centers:

30. Medulla Oblongata
Projection fiber tracts cross here - right to left

31. Regions of the Brain: Brain Stem
Reticular Formation
Diffuse mass of gray matter along the brain stem
Involved in motor control of visceral organs

32. Reticular Formation of the Brain Stem
Figure 7.16b