1. Chapter 34 Organization and Control of Neural Function
Essentials of Pathophysiology
Chapter 34 Organization and Control of Neural Function

2. Pre lecture quiz T F
The dorsal horn cell columns contain the afferent (sensory) neurons and the ventral horn cell columns contain the efferent neurons.
The brain is divided into three regions: the hindbrain, the midbrain, and the forebrain.
The parasympathetic nervous system functions in maintaining vital functions and responding when there is a critical threat to the integrity of the individual—the “fight-or-flight” response.
The blood-brain barrier and the cerebrospinal fluid–brain barrier protect the brain from substances in the blood that would disrupt brain function.
Cerebrospinal fluid helps maintain a constant ionic environment that serves as a medium for diffusion of nutrients, electrolytes, and metabolic end products into the extracellular fluid surrounding central nervous system neurons and glia.

3. Pre lecture quiz
______________ are the functioning cells of the nervous system.
The _________________ nervous system contains two divisions: sympathetic and parasympathetic.
Inside the skull and vertebral column, the brain and spinal cord are loosely suspended and protected by several connective tissue sheaths called the _________________.
Neurons communicate with each other through structures known as ________________, of which there are two types: electrical and chemical.
The main ___________________ for the autonomic nervous system are acetylcholine and the catecholamines, epinephrine and norepinephrine, which control neural function by selectively causing excitation or inhibition of action potentials.
Autonomic
meninges
Neurons
neurotransmitters
synapses

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

5. Peripheral nervous tissue
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

6. What is the function of each?
Identify
Microglial cell
Neuron
Oligodendritic cell
Ependymal cell
Astrocyte E C B D
What is the function of each? A

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

8. Answer
False 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.

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

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

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

12. General Organization of the Nervous System
Begins as a hollow tube
First segments of the tube become the brain
Forebrain
Midbrain
Hindbrain

13. Organization of the Spinal Cord
Dorsal
Afferent
Sensory
Ventral
Efferent
Motor

14. 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?

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

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

17. Answer
Dorsal
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.

18. 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

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

20. 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

21. 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

22. 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

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

24. Question
Which part of the brain maintains vital functions like breathing, heart rate, and digestion?
Forebrain
Midbrain
Hindbrain
Cerebellum

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

26. 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

27. 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

28. 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

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

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

31. 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

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

33. 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

34. 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

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

36. Answer
True 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!