The document provides an overview of the nervous system including neurons, supporting cells, and the functions of different parts of the brain and spinal cord. It discusses how stimuli are received and transmitted via neurons and supporting cells. The autonomic nervous system is divided into the sympathetic and parasympathetic divisions, which use different neurotransmitters and have opposing effects on the body. The sympathetic division, which uses catecholamines like epinephrine, is also known as the fight-or-flight response as it prepares the body for emergency situations.

1. Nervous System Physiology
Review

2. Neurons
• Dendrites receive stimuli
• Stimuli pass down axons
• Schwann cells contain myelin
(“white matter”)
• Help increase speed of impulse
transmission

3. Supporting Cells
• Peripheral nervous tissue
– Schwann cells: wrap a layer of myelin around axons
– Satellite cells: separate nervous cells from supporting
tissue
• Central nervous tissue
– Oligodendroglia: myelinating cells
– Astroglia: regulate ion content in intercellular fluid
– Microglia: phagocytes
– Ependymal cells: line the neural tube cavity

4. Identify
• Microglial cell
• Neuron
• Oligodendritic cell
• Ependymal cell
• Astrocyte
What is the
function of each?

5. Question
Tell whether the following statement is true or
false.
All neurons are myelinated.

6. False Answer
Rationale: The myelin sheath increases the
speed of impulse transmission (the impulse
can skip over the myelinated/insulated parts
of the neuron), but speed is not important
everywhere (like the digestive tract). If every
neuron was myelinated, neurons would take
up a lot more space, too.

7. The Basics of Cell Firing
• Stimulus opens Na+ gates Action
potential
• At threshold, more Na+
gates open
Threshold
• Na+ enters cell: potential
depolarization
• K+ gates open Resting
• K+ diffuses out: membrane
repolarization potential Stimulus

8. Synaptic
Transmission
• What is
happening at
stages 1–5?
• What will result if
you block stage 2?
• Stage 3?
• Stage 4?

9. Neuron Secretions
• Neurotransmitters
– Amino acids
– Peptides
– Monoamines
• Neuromodulators
– Attach to receptors and change their
response to neurotransmitters
• Neurotrophic factors
– Neuron survival and to develop connections
between neurons

10. General Organization of the Nervous System
• Begins as a hollow
tube
• First segments of
the tube become
the brain

11. Organization of the Spinal Cord
• Dorsal
– Afferent
– Sensory
• Ventral
– Efferent
– Motor

12. Scenario
A woman developed polyneuropathy.
• Her spinal nerves were damaged
• She lost the ability to tell where her body was positioned
• She has to look every time she takes a step, to tell where
she is moving her feet to
Question:
• What parts of her spinal nerves were damaged?

13. Cell Columns of the Spinal Cord
• What
problems
would you
expect in A
someone
who B
suffered
ischemia C
to:
– Area A
– Area B
– Area C

14. Question
If you place your hand on a hot surface, which
ganglion carries the impulse to the spinal
cord?
b. Ventral
c. Dorsal
d. Interneuron
e. Association neuron

15. a. Dorsal Answer
Rationale: Afferent neurons carry sensory
impulses to the spinal cord through the dorsal
root ganglion; efferent neurons carry motor
responses through the ventral root ganglion
to effector cells in the tissue.

16. Layers of the White Matter
• Archi layer
– Connects neighboring segments
– Contains neurons  reticular
activating system
• Paleo layer
– Fibers reach to the brain stem
• Neo layer
– Pathways for bladder control and
fine motor skills
– Develop by fifth year of life

17. Brain Regions
• Cerebrum
• Thalamus
• Hypothalamus
• Cerebral peduncles
• Cerebral aqueduct
• Colliculi
• Cerebellum
• Pons
• Medulla oblongata

18. Functions of the Hindbrain
• Medulla oblongata, cerebellum, and pons
• Reflex centers for heart and respiration rates, coughing,
swallowing, vomiting, etc.
• Gives rise to cranial nerves V–XII controlling viscera,
hearing, facial, and mouth/throat functions
• Cerebellum allows fine motor coordination

19. Functions of the Midbrain
• Cerebral peduncles carry nerve fibers from the
cerebrum to the hindbrain
• Cerebral aqueduct lets cerebrospinal fluid drain
from the fourth ventricle inside the cerebrum
• Superior colliculi control reflex eye movements
• Inferior colliculi control reflex reactions to sound
• Gives rise to cranial nerves III and IV, controlling eye
movement

20. Functions of the Forebrain
• Thalamus: “switchboard” or relay station for impulses going to
and coming from the cerebrum
• Hypothalamus: homeostatic control
• Cerebrum
• Gives rise to cranial nerves I and II, for smell and sight

21. Cerebrum
• Frontal lobe: motor, anticipation
• Parietal lobe: somatosensory
• Temporal lobe: hearing, memory
• Occipital lobe: vision
• Limbic system: emotional

22. Question
Which part of the brain maintains vital functions
like breathing, heart rate, and digestion?
b. Forebrain
c. Midbrain
d. Hindbrain
e. Cerebellum

23. a. Hindbrain Answer
Rationale: Also known as the brain stem, this is
the vasomotor center that controls
cardiopulmonary function and digestion.

24. Dura Mater
• Has two layers
• Inner layer bends over
to form a fold (falx
cerebri) that separates
the cerebral
hemispheres
• It forms a second fold
(tentorium) that holds
the cerebrum up off
the cerebellum

25. Dura Mater
(cont.)
• Between the layers of
the dura, at the base of
each fold, venous blood
drains out of the brain
in a sinus
• Bridging veins carry
blood from the brain
across the inner layer of
the dura mater to the
sinus
• The sinus also collects
cerebrospinal fluid

26. Arachnoid
• Lies just beneath the dura
mater
• Waterproof
• Cerebrospinal fluid (CSF)
lies under the arachnoid
to cushion the brain
• Extensions of the
arachnoid (villi) poke
through the inner layer of
the dura mater into the
sinuses, to let CSF drain
into the sinuses

27. Pia Mater
• Lies right on the surface
of the brain
• Holds the cerebral
arteries in place

28. Meninges and Meningeal Spaces
• Epidural space: meningeal arteries
• Dura mater
– Subdural space: bridging veins
• Arachnoid
– Subarachnoid space: cerebral arteries,
cerebrospinal fluid
• Pia mater

29. Cerebrospinal Fluid
• Leaks out of capillaries inside the brain’s hollow
ventricles
– Composition controlled by the blood-brain barrier
• Passes out an opening below the cerebellum
• Circulates around the brain and spinal cord in the
subarachnoid space
• Passes through arachnoid villi into blood in the dural
sinuses and is returned to the heart

30. Autonomic Nervous System
• Sympathetic
– Catecholamines
– Epinephrine, norepinephrine, dopamine
– Attach to adrenergic receptors
• Parasympathetic
– Acetylcholine
– Attaches to cholinergic receptors

31. Adrenergic Neurotransmitters
• Synthesized in the sympathetic system
• Attach to adrenergic receptors
– Alpha-1 receptors: constrict blood vessels
– Alpha-2 receptors: negative feedback to stop
neurotransmitter release
– Beta-1 receptors: speed and strengthen heart
– Beta-2 receptors: bronchodilation
• Neurotransmitter is removed from synapse by
reuptake or degraded by enzymes

32. Cholinergic Neurotransmitter—
Acetylcholine
• Released from parasympathetic system and from
motor neurons
• Attaches to cholinergic receptors
– Nicotinic receptors: excite skeletal muscle cells
– Muscarinic receptors: slow heart, stimulate GI tract,
vasodilate
• Neurotransmitter is removed from synapse by
acetylcholinesterase

33. Question
Tell whether the following statement is true or
false.
The sympathetic division of the ANS is also
known as fight-or-flight.

34. True Answer
Rationale: The SNS is characterized by the
release of adrenaline, which results in pupil
dilation, bronchodilation, and increased HR,
BP, and glucose production—all the things
that come in handy when you are running
from something!