1. NERVOUS SYSTEM Aids in remembering, thinking, moving, being aware, and coordinating all other body functions to maintain homeostasis.
Chapter 9

2. 2 Parts of the Nervous System
Central Nervous System (CNS)
Brain and spinal cord
Peripheral Nervous System (PNS)
nerves

3. Nervous System Functions
SENSORY
Neurons contain sensory receptors (cells) at their ends.
Detect changes inside and outside the body
Convert information into nerve impulses that travel through the PNS to the CNS
INTEGRATIVE
In the CNS, impulses are brought together creating sensations, adding memory, producing thoughts, etc.
Making conscious and subconscious decisions
MOTOR
Impulses are carried from the CNS to effectors (muscles and glands).
2 categories
Somatic Nervous System
Consciously controlled; skeletal muscle
Automatic Nervous system
Involuntary; heart, smooth muscle, glands

5. Brain and Spinal Cord Protected by layered membranes called meninges.
1. Dura mater (outermost layer- contains blood vessels)
2. Arachnoid mater (no blood vessels)
3. Pia mater (thin, contains nerves and blood vessels
that nourish the cells of the brain and spinal cord)
Cerebrospinal fluid (CSF) –clear,
watery fluid b/w the arachnoid
and pia maters that is a shock
absorber. Secreted by masses
of specialized capillaries called
choroid plexuses.

8. Brain Structure and Functions
Contains 100 billion multipolar neurons
Divided into 4 major parts:
Cerebrum
Diencephalon
Brainstem
Cerebellum

9. 4 main parts of brain Brain area Location Function Cerebrum Cerebellum
Largest, most of cranial cavity
Sensory and motor functions
Higher mental functions
-memory
-reasoning
Cerebellum
Posterior and inferior region
Coordination
Balance
Muscle tone

11. Brain area Location Function
Diencephalon
Thalamus
Hypothalamus
Middle
Limbic system-controls emotional experience and expression
1.Process sensory info (pain, touch, temp)
2.Maintains homeostasis: appetite center, sleep-wake, water balance
Brainstem
Medulla
Pons
Midbrain
Base of brain
Connect various parts of NS
Regulates visceral activities
1.Breathing, heart rate
2.Origin of cranial nerves
3.Coordinate head/eye movements to sound& light

13. STRUCTURE OF CEREBRUM
Cerebral cortex is the outermost layer of gray matter that contains 75% of all neuron cell bodies of the NS.
Left & Right cerebral hemispheres are connected by a bridge of nerve fibers called the corpus callosum.
Surface contains many ridges called gyri (gyrus)
separated by grooves. Shallow groove is a sulcus and
a deep groove is a fissure.
Longitudinal fissure separates the right and left hemispheres.
Transverse fissure separates the cerebrum from the cerebellum.
Longitudinal
fissure
Transverse
fissure

14. 5 lobes-frontal, parietal, temporal, occipital, insula (inner)
4 ventricles

15. 12 Pairs of Cranial Nerves
**Olivia obtains one terrible temper about false
videos gone viral about her
**Oh once one takes the anatomy final very good
vacations are heavenly

16. 12 Pairs of Cranial Nerves
Nerve Function
1. Olfactory smell
2. Optic vision
3. Oculomotor moves/focus eye
4. Trochlear moves eye
5. Trigeminal chewing
6. Abducens moves eye
7. Facial facial expression, taste
8. Vestibulocochlear equilibrium, hearing
9. Glossopharyngeal swallowing
10. Vagus heart, digestion
11. Accessory neck
12. Hypoglossal move tongue

17. SPINAL CORD (pg 247) -where spinal cord ends Foramen Magnum
Contains 31 segments, each giving rise to a pair of spinal nerves.   
Foramen Magnum
-Where the spinal cord begins
Cervical Enlargement
-supplies nerves to upper limbs
Spinal Cord
Vertebral Canal
Lumbar Enlargement
-supplies nerves to lower limbs
-where spinal cord ends

19. Cross section of spinal cord (pg. 233)
Posterior Sulcus: divides spinal cord into right and left halves.
White Matter: myelinated neurons
Contains CSF
Anterior fissure
Divides spinal cord into right and left halves
Unmyelinated neurons

20. Spinal Cord Functions (pg. 234)
1. Conducting impulses
2 way communication system
Ascending tracts: carry sensory info to the brain (afferent=arrives)
Descending tracts: conduct motor impulses from the brain to effectors (efferent=exit)
2. Spinal Reflexes:
Patellar Reflex
Withdrawal Reflex

21. Patellar reflex: uses only 2 neurons (sensory and motor), helps maintain upright posture
Withdrawal reflex: sends sensory messages to spinal cord and out to motor neurons, aids in limiting tissue damage caused by touching something harmful.

23. NERVE PATHWAYS (PG. 229)
These are routes nerve impulses follow as they travel through the nervous system.
The simplest of these pathways includes only a few neurons called a reflex arc.
Reflexes are automatic responses to stimuli that help maintain homeostasis.
Heart rate blood pressure
Coughing vomiting
Breathing sneezing

24. Nervous System Functions
SENSORY
Neurons contain sensory receptors (cells) at their ends.
Detect changes inside and outside the body
Convert information into nerve impulses that travel through the PNS to the CNS
INTEGRATIVE
In the CNS, impulses are brought together creating sensations, adding memory, producing thoughts, etc.
Making conscious and subconscious decisions
MOTOR
Impulses are carried from the CNS to effectors (muscles and glands).
2 categories
Somatic Nervous System
Consciously controlled; skeletal muscle
Automatic Nervous system
Involuntary; heart, smooth muscle, glands

25. The typical neuron

26. Neurons Nervous tissue contains masses of nerve cells called neurons.
Specialized to react to physical and chemical changes.
Transmit info in the form of electrochemical changes called nerve impulses.
Bundles of axons make nerves.
Also contains neuroglia cells that provide physical support, insulation,
and nutrients for neurons.

27. Review of key neuron parts

29. CLASSIFICATION OF NEURONS
Vary in structure, size, shape, and the number of connections they make with other neurons.
3 major structural groups (pg. 218)
Bipolar: cell body has 1 axon & 1 dendrite (found in eyes, ears, nose )
Unipolar: cell body has 1 axon (lead to PNS and CNS, can form ganglia)
Multipolar: cell body has 1 axon & many dendrites (found in brain and spinal cord)

30. 3 major functions of neurons
Sensory neurons (afferent)
Carry impulses from PNS to CNS
Receptor cells found at end of dendrites or in skin or sensory organs
Most are unipolar
Interneurons
In brain and spinal cord
Transmit impulses from one part of the brain or spinal cord to another
multipolar
Motor neurons (efferent)
Carry impulses out of brain or spinal cord to effectors

34. NEUROGLIAL CELLS (PG. 215) Microglial cells
Neurons cannot exist without these cells
Outnumber neurons in CNS
Can divide (neurons do not normally divide)
4 TYPES
Microglial cells
Support neurons and phagocytize bacterial cells and cellular debris
Oligodendrites
Align along nerve fibers
Provide insulating layers of myelin (myelin-forming cells)
Astrocytes
Found b/w neurons and blood vessels
Provide structural support
Regulate nutrient and ion concentration within tissue
Form scar tissue that fill spaces following an injury in the CNS
“blood-brain barrier”
Shields delicate tissue from chemical fluctuations
Some drugs can get in some can’t

35. 4.) Ependymal cells
Forms an epithelia-like membrane that covers specialized brain parts (cells that line the central canal)
Forms inner linings that enclose spaces within the brain and spinal cord
*Schwann Cells: are neuroglial cells that form a myelin sheath around axons.

37. So how do Neurons Communicate with each other
So how do Neurons Communicate with each other?????? Impulses travel from one neuron to another to reach the CNS by crossing a synapse

38. THE SYNAPSE The junction between two communicating neurons
Synaptic cleft: the gap between 2
communicating neurons.
Synaptic transmission:
-process of the impulse crossing
the cleft
-one-way process carried out by
neurotransmitters
-neurotransmitters can be excitatory or inhibitory
-about 50 neurotransmitters in
nervous system (pg. 226 chart)

40. Steps of a Nerve Impulse/ Synaptic Transmission4 3
Steps of a Nerve Impulse/ Synaptic Transmission 5 2 1 6

41. Nerve Impulse Animation

43. NERVE IMPULSES – action potential
The surface of a cell membrane is polarized (electrically charged)
At rest, membrane potential is negative and the membrane is polarized. Na K Na
When the membrane reached its threshold stimulus, Na channels open, Na ions diffuse in, and membrane is depolarized.
K+K+Na+Na+
Na+Na+ K+K+
K channels open, K ions diffuse out, and the membrane repolarizes. Na
K++++++

44. NERVE IMPULSES –action potential
A wave of action potentials travels the length of the axon as a nerve impulse.
Nerve impulse conduction is an ALL-OR-NONE response – if neuron responds at all, it responds completely!

45. Video
Nerve Impulse & Action Potential

48. A wave of action potentials is occurring throughout the membrane of a neuron.
*This is an ALL-OR-NONE response*

49. SYNAPSE AFFECTORS/OTHER PROBLEMS
Caffeine: stimulates the nervous system by lowering the threshold at the synapse so neurons are more easily excited.
Antidepressants: keeps the neurotransmitter, serotonin, in the synapse longer.
Epileptic seizures: caused when nerve impulses reach the synaptic knob to fast, exhausting the neurotransmitter.

50. Multiple sclerosis (MS): is a disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelinization and scarring. The body’s immune system attacks and damages the myelin. Axons can no longer effectively conduct signals. Symptoms include muscle weakness, spasms, difficulty in moving, coordination,
balance, speech, or
swallowing, visual
problems, fatigue, and
bladder and bowel
difficulties.

51. Miscellaneous/Problems
Subdural hematoma: collection of blood from broken blood vessels that will increase pressure in the skull and will lead to functional losses or death.
Cerebral palsy: partial paralysis and lack of muscular coordination caused by damage to the cerebrum.