The nervous system allows animals to respond to stimuli and survive. Simple animals have nerve nets while more complex animals have bundled axons called nerves. The central nervous system includes the brain and spinal cord while the peripheral nervous system connects them via nerves and ganglia. The brainstem controls arousal and sleep. The cerebellum coordinates movement. The diencephalon contains the thalamus, hypothalamus, and epithalamus which regulate homeostasis. The cerebrum is divided into four lobes and has a highly convoluted cortex that allows for specialized functions in different regions.

1. THE NERVOUS
SYSTEM

2. Introduction
• Basic to the functioning of any animal.
• In order to survive and reproduce, an animal must
respond to environmental stimuli both external and
internal.
• Provides both immediate and long-term responses.

3. Circuits of neurons and supporting cells
• Most animals with nervous systems have clusters of
neurons that perform specialized functions.
• Such clustering is absent in the cnidarians.
• Most cnidarians have radially symmetrical bodies.
• Most cnidarians have nerve nets.

4. Nerves vs. Nerve Nets
• Simple animals, ex. Cnidarians, have nerve nets.
• More complex animals: axons of multiple nerve cells are
bundled together to form nerves.
• Better suited to controlling elaborate movements than a
single diffuse nerve net.

5. Cephalization
• Animals with elongated, bilaterally symmetrical bodies
have even more specialized nervous systems.
• Such animals exhibit cephalization.

6. Nervous System Organization
• Look at the picture on page 1065

7. CNS & PNS in Vertebrates
• CNS= Central Nervous System
• Brain and spinal cord.
• PNS= Peripheral Nervous System
• Nerves and ganglia.
• Regional specialization is a hallmark of both systems.
• The PNS connects to the CNS

8. CNS & PNS
Central nervous
system (CNS) Peripheral nervous
system (PNS)
Brain Cranial
Spinal cord nerves
Ganglia
outside
CNS
Spinal
nerves
Figure 48.19

9. Spinal cord
• The spinal cord runs lengthwise inside the spine.
• It conveys information to and from the brain and
generates basic patterns of locomotion.
• It acts independently of the brain.

10. Reflexes
• The spinal cord acts as part of the simple nerve circuits
that produce reflexes.
• A reflex protects the body by triggering a rapid,
involuntary response to a particular stimulus.
• Ganglia run along the outside of the spinal cord

11. Origin of the brain & spinal cord
• Derived from the dorsal embryonic
nerve cord.
• During development it is transformed
into the narrow central canal of the
spinal cord and the ventricles of the
brain.

12. Fluid & Matter
• Both the central canal and the brain are filled with
cerebrospinal fluid and Gray/White matter
• Cerebrospinal fluid: supplies the brain with essential
nutrients and hormones.
• Gray Matter- neuron cell bodies and dendrites
• White Matter- bundled axons

13. Glia in the CNS
• Ependymal cells- circulation of cerebrospinal fluid
• Microglia- protect from invading microorganisms
• Oligodendrocytes- function in axon myelination
• Astrocytes-structural support for neurons

14. PNS

15. Overall importance of PNS
• Transmits information to and from the CNS and plays a
large part in regulating an animal’s movement and internal
environment.
• Sensory information reaches the CNS along afferent (to
bring toward) PNS neurons.
• Instructions from the CNS reach the PNS along efferent
(to carry off) PNS neurons

16. Nerves
• Cranial Nerves:
• connect the brain with locations mostly in organs of the head and
upper body.
• Spinal Nerves:
• Run between the spinal cord and parts of the body below the head.

17. Systems of the PNS
• Motor Systems: neurons that carry information to
muscles.
• Autonomic Nervous System: regulates the internal
environment. This control is generally involuntary and is
split into three divisions: Sympathetic, Parasympathetic,
Enteric.

18. Sympathetic Division
• Corresponds to arousal and energy generation (fight-or-
flight).
• Inhibits saliva production
• Relaxes bronchi in the lungs
• Accelerates heart rate
• Secretion of epinipherene

19. Parasympathetic Division
• Promote calming and return to self- maintenance.
• Rest-and-digest
• Slows heart rate
• Promotes emptying of bladder
• Constricts bronchi in lungs

20. Enteric Division
• Networks of neurons in the digestive tract, pancreas, and
gallbladder.
• Also control peristalsis.

21. CNS

22. Brainstem

23. The Brain Stem
• Adult brainstem midbrain, the pons, and the
medulla oblongata.
• Sits at the bottom of the brain, on top of the spinal
cord.
• It relays the information between the spinal cord
and the brain.

24. Arousal and Sleep
• Controlled by the brainstem and cerebrum.
• Arousal= you are aware of surroundings.
• Sleep= external stimuli are received but not consciously
perceived.
• Reticular formation
• Sleep is an active process.
• Melatonin plays an important part in these processes.

25. Cerebellum

26. The Cerebellum
• Posterior
• Coordinates movements and balance, specifically helps
when you have to learn something new.
• Hand eye coordination

27. Diencephalon

28. The Diencephalon
• 3 parts: Thalamus, Hypothalamus, and Epithalamus.

29. Epithalamus
• Location of the pineal gland, origin of melatonin.
• Also contains capillaries that generate cerebrospinal fluid
from the blood.
• Cerebrospinal fluid: supplies the brain with essential
nutrients and hormones

30. Thalamus
• Main input center for center for sensory information going
to the cerebrum.

31. Hypothalamus
• Controls homeostasis
• Ex: body’s thermostat, regulate hunger & thirst.
• Source of posterior pituitary hormones and releasing
hormones that act on the anterior pituitary.
• Plays a role in sexual and mating behaviors, fight-or-flight,
and pleasure.
• Four F’s

32. Biological Clock Regulation
• Specialized nerve cells in the hypothalamus regulate
circadian rhythms, daily cycles of biological activities.
• As stated previously: regulates sleep, body temperature,
hunger, and hormone release.
• Molecular mechanisms that direct periodic gene
expression and cellular activity.
• Typically synchronized with the day and night.

33. Biological Clock Regulation cont.
• In mammals circadian rhythms are coordinated by a
group of neurons in the hypothalamus called the
superchiasmatic nucleus (SCN).
• The SCN determines the circadian rhythm of the whole
animal.

34. Cerebrum

35. The Cerebrum
• Divided into right and left cerebral hemispheres.
• Each hemisphere is made up of an outer covering of gray
matter, the cerebra cortex; internal white matter; and
groups of neurons called basal nuclei.

36. Basal Nuclei
• Basal Nuclei are important centers for planning and
learning movement sequences.
• Damage in this brain region during embryonic
development can result in cerebral palsy, a defect
disrupting how motor commands are issued to the
muscles.

37. Cerebral Cortex
Frontal lobe Parietal lobe
Somatosensory
Speech
association
Frontal
area
association
area Taste
Reading
Speech
Hearing
Visual
Smell association
area
Auditory
association
area
Vision
Temporal lobe Occipital lobe
Figure 48.27

38. The Cerebral Cortex
• 4 different lobes: frontal, temporal, occipital, and parietal.
• Frontal lobe: plans actions and controls your movement.
• Size fits muscles required. Leg- Knee- Hip.
• Parietal lobe: Sensory.
• Size fits sensory info.
• Temporal lobe: Auditory & Memory Formation
• Occipital lobe: Visual information

39. Cerebral Cortex
• Accounts for 80% of total brain mass.
• Highly convoluted, allows for large surface area.
• The corpus callosum is a thick band of axons that
enables communication between the two sides of the
cerebral cortex.

40. Language and speech
• Damage to particular regions of the cortex by injuries,
strokes, or tumors can change in a person’s behavior.
Max
Hearing Seeing
words words
Min
Speaking
Generating
Figure 48.29
words
words

41. Broca’s Area
• Pierre Broca studied people who could understand
language, but not speak it.
• Located in the front part of the primary motor cortex, in the
frontal lobe.
• Controls the speaking and the generating of the brain.

42. Wernicke's Area
• Karl Wernicke studied damage to the back of the left
temporal lobe.
• People could speak, but not comprehend speech.

43. Lateralization
• Both hemisphere’s have different functions.
• Generally:
• Left side= language/speech, math, logic
• Right side= patterns, facial recognition (creative side)

44. Emotions
• Limbic System: group of structures surrounding the
brainstem.
• Dedicated to emotion, motivation, olfaction, behavior, and
memory.
Thalamus
Hypothalamus
Prefrontal cortex
Olfactory
bulb
Amygdala Hippocampus
Figure 48.30

45. Memory & Learning
• Hippocampus- Forms new memories
• Amygdala- Fear & anxiety
• Short term memories are made by links made in the
hippocampus. When memories need to be made long
term, the links are replaced by links in the cerebral cortex

46. Long Term Potentiation
• LTP: Involves an increase in the strength of
synaptic transmission

47. Evolution of Cognition in Vertebrates
• In humans, the outermost part of the cerebral cortex is
called the neocortex.
• The outer part of the avian cerebral cortex is called the
pallium.
• The common ancestor of birds and humans probably had
a pallium as it still present in birds.

48. Schizophrenia
• 1% of the population has it.
• Distorted perception of reality, hallucinations.
• Two lines of evidence suggest that schizophrenia affects
neurons that use dopamine:
• Speed- produces dopamine and produces same effects as schiz.
• Many drugs used for treatment block dopamine

49. Depression
• Two types:
• Major depressive disorder- Extreme Sadness
• Bipolar Disorder-
• Manic phase extremely energetic
• Depressive phase, same as m.d.d

50. Drug Addiction
• Altered activity of the brain’s reward system, which
normally provides motivation for actions.

51. Alzheimer’s
• Mental deterioration where plaques form in the brain.
• Confusion and memory loss.

52. Parkinson's
• Motor disease
• Caused by the death of dopamine-secreting neurons
• No cure at the time

53. Stem Cell Based Therapy
• The adult human brain contains stem cells that can
differentiate into mature neurons, this will be helpful for
replacing neurons lost to a disease or trauma.

54. Conclusion
• Your nervous system has several different parts that play
their own special parts, but at the same time they work
together.
• Only 10% of your brain is made up of neurons, the other
90% is glia.
• There are several neurological diseases.