1. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 34 Organization and Control of Neural Function

2. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Neurons Dendrites receive stimuli Stimuli pass down axons Schwann cells contain myelin (“white matter”) Help increase speed of impulse transmission

3. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins 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. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Identify Microglial cell Neuron Oligodendritic cell Ependymal cell Astrocyte What is the function of each ?

5. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Tell whether the following statement is true or false: All neurons are myelinated.

6. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer False 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. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins 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 Threshold potential Resting membrane potential Stimulus Action potential

8. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins 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

9. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins General Organization of the Nervous System Begins as a hollow tube First segments of the tube become the brain

10. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Organization of the Spinal Cord Dorsal –Afferent –Sensory Ventral –Efferent –Motor

11. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins 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?

12. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Question If you place your hand on a hot surface, which ganglion carries the impulse to the spinal cord? a.Ventral b.Dorsal c.Interneuron d.Association neuron

13. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer b.Dorsal 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.

14. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins 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

15. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Functions of the Hindbrain Medulla oblongata, cerebellum, and pons Reflex centers for heart and respiration rates, coughing, swallowing, vomiting, etc. Give rise to cranial nerves V–XII controlling viscera, hearing, facial, and mouth/throat functions Cerebellum allows fine motor coordination

16. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins 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

17. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins 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

18. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Cerebrum Frontal lobe: motor, anticipation Parietal lobe: somatosensory Temporal lobe: hearing, memory Occipital lobe: vision Limbic system: emotional

19. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Which part of the brain maintains vital functions like breathing, HR, and digestion? a.Forebrain b.Midbrain c.Hindbrain d.Cerebellum

20. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer c.Hindbrain Also known as the brainstem, this is the vasomotor center that controls cardiopulmonary function and digestion.

21. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins 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

22. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins 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

23. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins 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

24. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Pia Mater Lies right on the surface of the brain Holds the cerebral arteries in place

25. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Meninges and Meningeal Spaces Epidural space: meningeal arteries Dura mater –Subdural space: bridging veins Arachnoid –Subarachnoid space: cerebral arteries, cerebrospinal fluid Pia mater

26. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins 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

27. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Autonomic Nervous System Sympathetic –Catecholamines –Epinephrine, norepinephrine, dopamine –Attach to adrenergic receptors Parasympathetic –Acetylcholine –Attaches to cholinergic receptors

28. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Adrenergic Neurotransmitters Synthesized in the sympathetic system Attach to adrenergic receptors –α 1 receptors: constrict blood vessels –α 2 receptors: negative feedback to stop neurotransmitter release –β 1 receptors: speed and strengthen heart –β 2 receptors: bronchodilation Neurotransmitter is removed from synapse by reuptake or degraded by enzymes

29. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins 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

30. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Tell whether the following statement is true or false: The sympathetic division of the ANS is also known as fight- or-flight.

31. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer True The SNS is characterized by the release of adrenaline, which results in pupil dilation, bronchodilation, increased HR, BP, and increased glucose production (all the things that come in handy when you are running from something!).