1. Chapter 49
Nervous Systems

2. Objectives To learn: the nervous systems of different animals
the nervous systems of vertebrates
the parts of the brain and their functions

3. Nervous Systems of Animals
Hydra (cnidarian)
Sea Star (echinoderm)
Absence of clustering neurons
Radial symmetry
Habitat of freshwater ponds, lakes, & streams
Nerve net
Series of interconnected nerve cells that control the contraction and expansion of the gastrovascular cavity
Set of radial nerves connecting to a central nerve ring
Radial symmetry
Habitat of oceans

4. Nervous Systems of Animals
Planarian (flatworm)
Nematode (nematoda)
Small brain and longitudinal nerve cords constitute the CNS
Bilateral symmetry
Habitat of both saltwater & freshwater ponds & rivers
4 peripheral nerves run the length of the body
Nerve ring surrounding pharynx, serving as the brain
Bilateral symmetry
Habitat of oceans to soils

5. Nervous Systems of Animals
Clam (mollusca)
Squid (mollusca)
Nerve network & series of paired ganglia
No brain
Bilateral symmetry
Habitat of mud & sand in bodies of water
Complex brains
Bilateral symmetry
Cephalopod
Habitat of various oceans

6. Nervous Systems of Vertebrates
Vertebrates (chordata)
Brain and spinal cord form the Central Nervous System (CNS)
Brain provides integrative power that underlies the complex behavior of vertebrates
Spinal cord, running along the spine, conveys info to & from the brain & generates basic patterns of locomotion
Nerves and ganglia form the Peripheral Nervous System (PNS)
Transmits info to & from the CNS
Plays an important role in regulating
movement & internal environment
Have backbones and spinal cords

7. Spinal Cord
Acts independently of the brain as part of the simple nerve circuits that produce reflexes
The body’s automatic responses to certain stimuli
Protects the body by triggering a rapid, involuntary response to a particular stimulus
ex//: automatically pulling your hand off of a hot surface

8. Central nervous system (CNS) Peripheral nervous system (PNS) Brain
Fig. 49-4
Central nervous
system (CNS)
Peripheral nervous
system (PNS)
Brain
Cranial
nerves
Spinal cord
Ganglia
outside
CNS
Spinal
nerves

9. Comprehension Check
Label each component as either the part of the central nervous system (CNS) or peripheral nervous system (PNS): 1. ____ cranial nerves 2. ____ spinal nerves 3. ____ brain 4. ____ spinal cord 5. ____ ganglia
PNS
PNS
CNS
CNS
PNS

10. White Matter v. Gray Matter
White matter- consists of bundled axons that have myelin sheaths, which give the axons a whitish appearance
in the spinal cord, it lies on the outside, consistent w/ the function in linking the CNS & PNS
In the brain, it lies on the inside, reflecting the role of signaling between neurons of the brain in learning, feeling emotions, processing info, etc.
Gray matter- consists mainly of neuron cell bodies, dendrites, and unmyelinated axons
Gray matter
White
matter
Ventricles

11. Glia- cells that maintain homeostasis, form myelin, & provide support and protection for neurons in the brain.
Ependymal cells- line the ventricles & have cilia that promote circulation of the cerebrospinal fluid
Microglia- protect the nervous system from invading microorganisms
Oligodendrocytes- functions in axon myelination
Radial glia- critical role in the development of the nervous system by giving rise to the CNS in embryos, and can act as stem cells
Astrocytes- provide a structural support for neurons & regulate the extracellular concentrations of ions and neurotransmitters
can facilitate info transfer at synapses & in some instances can release neurotransmitters
Astrocytes adjacent to active neurons cause nearby blood vessels to dilate, increasing blood flow to the area & enabling the neurons to obtain oxygen & glucose more quickly
During development, they induce cells that line the capillaries in the CNS to form tight junctions
Can act as stem cells

12. Divisions of the Autonomic Nervous System
Autonomic Nervous System- regulates the internal environment by controlling smooth & cardiac muscles and the organs of the digestive, cardiovascular, excretory, & endocrine systems. It is generally involuntary.
Enteric Division- consists of networks of neurons in the digestive tract, pancreas, & gallbladder. Neurons of the enteric division control secretion & also control the smooth muscles that produce peristalsis.
Parasympathetic Nervous System- activation causes opposite responses that promote
calming & a return to self-maintenance functions.
lowers heart rate
Enhances digestion
Increases glycogen production
Sympathetic Nervous System- activation corresponds to arousal & energy
generation.
Heart beats faster
Digestion is inhibited
Liver converts glycogen to glucose
Secretion of epinephrine (adrenaline) from adrenal gland

13. PNS Efferent neurons Afferent (sensory) neurons Motor system Autonomic
Fig
PNS
Efferent
neurons
Afferent
(sensory) neurons
Motor
system
Autonomic
nervous system
Hearing
Sympathetic
division
Parasympathetic
division
Enteric
division
Locomotion
Hormone
action
Gas exchange
Circulation
Digestion

14. Parts of the Brain

15. Reticular System
Reticular Formation- a diffuse network of neurons in the core of the brainstem.
determines which incoming info reaches the cerebral cortex
Filters info traveling to the cerebral cortex
The more info the cortex receives, the more alert and aware a person will be

16. Comprehension Check B E H C G F D A
Match each brain component to its corresponding function:
1. ___ Pons
2. ___ Thalamus
3. ___ Cerebrum
4. ___ Midbrain
5. ___ Hypothalamus
6. ___ Epithalamus
7. ___ Cerebellum
8. ___ Medulla Oblongata B
a. Controls homeostasis functions, including breathing, heart & blood vessel activity, swallowing, vomiting & digestion
b. Part of brainstem; helps control breathing; conducts impulses to & from the cerebellum, midbrain & medulla
c. Receives & integrates types of sensory info & sends coded sensory info along neurons to specific regions of the forebrain
d. Coordinates skilled skeletal muscle movement; involved in posture & balance; learning & remembering motor skills
e. Relays all sensory input to the cerebral cortex; involved in skeletal muscle actions & memory processing
f. Connects limbic system to other parts of the brain; secretion of melatonin by pineal gland & regulation of motor pathways & emotions
g. Controls & integrates the autonomic nervous system; regulates hormones, emotional behavior, temperature, eating & drinking
h. Intergrating center for memory, learning, emotions & other highly complex functions of the CNS E H C G F D A

17. Left and Right Hemispheres
Left Hemisphere
Right Hemisphere
Receives info from, and controls the movement of, the right side of the body
Governs ability to express language
More adept at math and logical operations
Receives info from, and controls the movement of, the left side of the body
Dominant in recognition of faces and patterns
Involved in spatial relations and nonverbal thinking

18. Cerebral Cortex
Parietal Lobe- receives and processes sensory info, involved with speech
Occipital Lobe- involved with vision
Temporal Lobe- involved with memory, emotion, hearing, and language
Frontal Lobe- involved with decision making, problem solving, and planning

19. Language Recognition & Production
Wernicke’s Area
Broca’s Area
located in the left temporal lobe
Involved with:
Language Comprehension
Language Recognition
Language Interpretation
located in the lower portion of the left frontal lobe.
Involved with:
Speech Production
Language Processing

20. Corpus Callosum
thick band of nerve fibers that divides the cerebrum into left and right hemispheres
Allows communication between the two hemispheres
When severed surgically, it stops communication between the two hemispheres (called corpus callosotomy)
Used to treat epileptic seizures
A patient with a split brain, when shown an image in his or her left visual field will be unable to vocally name what he or she has seen. This is because the speech-control center is in the left side of the brain in most people, and the image from the left visual field is sent only to the right side of the brain. Since communication between the two sides of the brain is inhibited, the patient cannot name what the right side of the brain is seeing.