Read the introductory section on the nervous system (p. 388).

Read the section on the organization of the nervous system (pp. 388-389).

• We’ll spend most of our remaining time on both nervous tissue and the central nervous system.
• This is the schedule for the nervous system:
  • Week 11: Introduction to Nervous Tissue (Ch. 11)
  • Week 12: CNS – The Brain (part of Ch. 12)
  • Week 13: CNS – The Spinal Cord (part of Ch. 12); PNS – Nerves and Reflexes (parts of Ch. 13)
  • Week 14: Autonomic Nervous System (beginning part of Ch. 14)

Read the section on the histology of nervous tissue (pp. 389-397).

• Make sure you learn the five types of neuroglia, where they’re found (CNS/PNS), and the general function of each.
  • See this nice site on the neuroglia.
• In terms of the neurons, don’t worry about any of the subcellular structures described here (perikaryon, soma, Nissl bodies, or neurofibrils).
  • See InterActive Physiology module – Nervous I: Orientation
  • See video clip – Neuron Structure.
    • This clip uses some words that aren’t important to me. Don’t worry about the terms soma (a.k.a. cell body), telodendria (a.k.a. axon branches), and synaptic knob (a.k.a. axon terminal).
    • Make sure you know the terms in parentheses instead.
• You should know that cell bodies are often found in clusters, and you should know what those clusters are called in both the CNS and PNS.
• You should know that both dendrites and axons are considered processes, and that bundles of axons are called tracts in the CNS and nerves in the PNS.
• You should know that neurons receive nerve impulses at their dendrites (and sometimes of their cell bodies) and conduct nerve impulses away from the cell body via the axon.
  • Marieb Fig. 11.4 is a fairly stylized version of what a neuron looks like.
  • In class, I usually show the students Alberts Fig. 18.26 because it shows the structural complexity of a neuron a little better.
• Understanding the two types of axon transport (anterograde and retrograde) is important. (Often comes up on exams.)
  • This transport refers to the movement of organelles and other subcellular structures along the axon, not the movement of ions
  • See two video clips of this process.
• You should know what is meant by the term myelin sheath and why the sheath is important.
  • There is a nice cross-sectional view of the myelin sheath on Marieb Fig. 11.5d.
• The three structural classes and the three functional classes of neurons are also important.
  • The structural classes are illustrated in Marieb Table 11.1, although I think Martini Fig. 12-3 is better.
  • Don’t worry about the anaxonic neuron on the Martini figure.

Regarding the section on neurophysiology (pp. 397-421):

• Some of this is review and you can read it if you like; other parts won’t be covered at all.
• I suggest you follow the lecture outline, as it has all of the material that I lecture on in class.
• Coding for the next series of topics:
  • Red = Definitely need to read
  • Purple = Optional; Probably contains some review material from muscle; Maybe just glance it over and see how comfortable you feel with it.
  • Blue = Not required; I don’t cover this in class

Neurophysiology

• Introduction (p. 397)
• Basic Principles of Electricity – Introduction (p. 397-398)
  • Some Definitions: Voltage, Resistance and Current (pp. 397-398)
    • Feel free to ignore Ohm’s law and any math.
  • Role of Membrane Ion Channels (pp. 398-399)
    • See InterActive Physiology module – Nervous I: Ion Channels
• The Resting Membrane Potential (pp. 399-400)
  • See InterActive Physiology module – Nervous I: Membrane Potential
• Membrane Potentials That Act as Signals – Introduction (p. 400-401)
  • This introduces the idea of hyperpolarization, which is new to the nervous system.
  • Graded Potentials (pp. 401-402)
    • Read the first three paragraphs only.
  • Action Potentials – Introduction (p. 402)
    • Generation of an Action Potential (pp. 402-404)
    • Propagation of an Action Potential (pp. 404-405)
      • See the following video clips – Mechanism of Action Potentials
        • Clip 1
        • Clip 2
        • Clip 3
      • This Martini figure does a nice summary of the action potential.
    • Threshold and the All-or-None Phenomenon (pp. 405-406)
    • Coding for Stimulus Intensity (p. 406)
    • Refractory Periods (p. 406)
    • Conduction Velocities (p. 407)
      • Stop reading at the Homeostatic Imbalance banner.
      • See video clip – Continuous vs. Saltatory Conduction.
    • See InterActive Physiology module – Nervous I: Action Potentials
• The Synapse – Introduction (p. 408)
  • Make sure you understand what’s meant by the presynaptic and postsynaptic neurons.
    • See video clip – Presynaptic and Postsynaptic Neurons.
  • Electrical Synapses (pp. 408-409)
  • Chemical Synapses (p. 409)
  • Information Transfer Across Synapses (pp. 409-410)
    • See video clip – Chemical Synapse.
  • Termination of Neurotransmitter Effects (p. 410)
  • Synaptic Delay (p. 411)
  • See InterActive Physiology module – Nervous II: Anatomy Review
    • Skip section on electrical synapses (p. 6)
• Postsynaptic Potentials and Synaptic Integration – Introduction (p. 411)
  • Excitatory Synapses and EPSPs (p. 411)
  • Inhibitory Synapses and IPSPs (p. 411)
  • Integration and Modifications of Synaptic Events
    • Summation by Postsynaptic Neurons (pp. 411-412), first four paragraphs only
      • The Image Gallery for this section has several figures from other books that demonstrate summation rather well.
    • Synaptic Potentiation (pp. 412-413)
    • Presynaptic Inhibition (p. 413)
  • See InterActive Physiology module – Nervous II: Synaptic Potentials and Cellular Integration
  • See InterActive Physiology module – Nervous II: Synaptic Transmission (pp. 1-9)
• Neurotransmitters and their Receptors (pp. 413-421)
  • You can see some of the neurotransmitter structures in Marieb Table 11.3.
  • Neurotransmitters are classified based on their function, so they can have diverse structures.
  • Just glance over some of their names. You’ve probably heard of some of these before. (And you’ll definitely hear about some of them later, too!)

Note: I don’t spend any time in class on the embryonic development of the brain (pp. 431-433) – a choice I make purely for time reasons – but you may find it interesting. You’re not responsible for that material, but it may help put what you’ll learn later in a more complete context (especially some of the vocabulary).

If you choose not to read this, then skip down to…

Read the section on brain regions and organization (p. 433).

• The text describes the gray matter in the cortex as “bark” like on a tree. In class, I usually describe the cortex as the peel on an orange. The pulp of the orange is composed of white matter.

Read the section on the ventricles (pp. 433-434).

• It’s not important to learn the names of the ventricles now. You’ll only be responsible for the anatomical details on the lab exam.
• The ventricles will be covered in more detail towards the end of this section, when you learn how the cerebrospinal fluid circulates through the ventricles. You’ll pick up what you need to know there.
• For now, just understand that they are filled with cerebrospinal fluid and lined with ependymal cells.

As with the bones, you will be held responsible for a subset of the brain’s anatomical features for the lecture portion of the course and a wider selection for Lab Exam 2.

• Click here a list of anatomical structures with which you should be familiar for lecture.
• Use the Lab Exam 2 Review Sheet for the list for the lab exam.

Read the introduction to the section on the cerebral hemispheres (pp. 434, 436).

• Items you should be able to identify/describe: the central sulcus, the longitudinal fissure, and the parieto-occipital fissure.
• The insula lobe lies deep to the temporal lobe.
  • The insula lobe is usually somewhat elusive in figures; you can see it as the blue-colored region on Marieb Fig. 12.6b.
  • We also have one model in the lab that shows the insula lobe.
• See Art-Labeling Activity for Marieb Fig. 12.6a.

Read the section on the cerebral cortex (pp. 436-441).

• Please refer to the lecture outline regarding what you need to know.
  • I don’t worry too much about the functional areas of the cerebral cortex.
  • You definitely need to know the difference between motor areas, sensory areas and multimodal association areas, and (in general) where they are located.
    • For example, you should know that the frontal eye field is in the frontal lobe (functionally speaking) and that the visual cortex is in the back half of the brain.
    • You certainly do NOT need to know specific locations of different functional areas nor their Brodmann numbers.
  • See Art-Labeling Activity for Marieb Fig. 12.8a.
• You can skip the Homeostatic Imbalance sections (pp. 439, 440).
• The last section (on lateralization) is interesting, but the take home message is just that there are preferences for certain skills on one side of the brain vs. the other.
  • Usually, the left hemisphere processes language, mathematical ability, and logic, while the right hemisphere processes artistic ability, emotion, and visual/spatial skills.
  • Someone is characterized as either “left cerebral-dominant” or “right cerebral-dominant” based on where his/her language centers are stronger.
  • In my personal opinion, I don’t find this topic physiologically relevant, but I suppose it makes good cocktail party conversation.
  • Martini Fig. 14-16 sums this up nicely.

Read the section on the cerebral white matter (pp. 441-443).

• You should also know the difference between commissures, association fibers and projection fibers. They’re illustrated nicely on Marieb Fig. 12.10.
  • An even better view can be seen on Tortora Fig. 14-12. In this figure, the brain tissue has been treated in such a way that the gray matter has been removed, giving a nice view of the white matter tracts.
• Make sure you know that the corpus callosum is the most prominent commissure in the brain.

Skim over the section on the basal nuclei (p. 443).

• Just know that they are regions of gray matter deep within the cerebral hemispheres and that they appear to function in motor outputs and cognition.
• Their individual names are not important.
• Their function(s) are somewhat explained in the last paragraph.

Read the section on the diencephalon (pp. 443-447).

• Make sure you understand that the diencephalon is composed of gray matter that is organized into three paired regions:
  • In terms of the thalamus:
    • It is composed of two thalamic nuclei, joined by a region of tissue called the intermediate mass.
    • Sensory data (from sensory receptors), motor input (from the basal nuclei and cerebellum), and emotion and visceral data (from hypothalamus) all converge on the thalamus.
    • The thalamus acts as a “switchboard” by editing and routing these impulses to the appropriate areas of the cerebral cortex.
  • In terms of the hypothalamus:
    • It is composed of clusters of nuclei beneath the thalamus.
    • The pituitary gland hangs beneath the hypothalamus on a stalk and the two maintain important functional connections (more on this in A&P2).
    • The hypothalamus is the visceral control center of the body and maintains homeostasis through the following activities:
      • center of the autonomic nervous system
      • center for emotional response
      • regulation of body temperature
      • regulation of food intake (appetite)
      • regulation of water balance and thirst (more on this in A&P2)
      • regulation of sleep/wake cycles (with pineal gland; see below)
      • regulation of the endocrine system (more on this in A&P2)
    • See video clip – Hypothalamus.
      • Only concentrate on the location of the hypothalamus,
  • In terms of the epithalamus:
    • The epithalamus contains the pineal gland.
    • The pineal gland secretes the hormone melatonin, which regulates our sleep/wake cycles (a.k.a. circadian rhythm).
    • Some additional information that I give in class:
      • Melatonin secretion is inhibited by light and is stimulated by darkness.
      • Melatonin secretion is disrupted by artificial light and this has been implicated as a cause/contributing factor to a higher incidence of cancer in people who work overnight shifts.
      • Melatonin (in medication form) is sometimes prescribed for people who suffer from insomnia, jet lag, or other circadian rhythm problems.
• See 3D Rotate video clip – The Brain.

Read the section on the brain stem (pp. 447-451).

• Make sure you understand that the brain stem is histologically similar to the spinal cord (we’ll get to that next week) and that it is important in maintaining survival activities.
• In terms of the midbrain:
  • The midbrain is the pathway to higher brain areas, as well as the link between the cerebellum and the cerebral hemispheres.
  • It contains centers for some of the cranial nerves (covered in the PNS).
  • The posterior view of the midbrain displays a structure called the corpora quadrigemina (“quadruplets”).
    • See Marieb Fig. 12.15c.
    • The corpora quadrigemina are composed of two superior colliculi and two inferior colliculi.
    • Both of these are associated with “head” reflexes.
    • The superior colliculi control head and eye reflexes, such as unconsciously tracking a moving object with your eye.
    • The inferior colliculi control hearing reflexes, such as when you turn your head towards a loud, startling noise.
    • These are visible on the sheep brain dissection. See Wood Fig. 25.12.
• In terms of the pons:
  • The word pons is Latin for “bridge” which is appropriate because the pons contains the fiber tracts that unite the brain and spinal cord.
  • It contains centers for some more of the cranial nerves.
  • The pons regulates breathing through two centers called the dorsal and ventral respiratory groups (DRG and VRG; more on this in A&P2).
• In terms of the medulla oblongata:
  • The medulla oblongata merges with the spinal cord.
  • It is the site of decussation – where the downward motor projection fibers from the hemispheres cross over from left to right (and vice versa).
  • It contains centers that control heart function, respiratory rate, and vasomotor tone (constriction and dilation of smooth muscle in walls of blood vessels).
• See 3D Rotate video clip – The Brain.

Read the two introductory paragraphs on the cerebellum (p. 451).

• You’ll see a little bit more of this during the brain dissection.

Read the section on cerebellar processing (p. 454).

• The four numbered steps do a nice job describing how the cerebellum functionally interacts with the rest of the brain.

In my day class, I don’t cover the next section on the functional brain systems – primarily because of time issues. There is some interesting material in here, especially the reticular activating system (RAS). Have you ever wondered why you get used to hearing a disruptive noise (i.e., a car alarm) the longer you hear it? Your RAS is responsible for this. You don’t need to read this section because I don’t find it that important from an anatomy and physiology perspective, but you may find it kind of neat from a “why does my body do that?” angle. You may hear more about these systems in a psychology course.

Read the section on the meninges (pp. 463-465).

• Make sure you can name and give characteristics of the three meninges.
• You can skip the section on the dural septa (p. 464).
• See Art-Labeling Activity for Marieb Fig. 12.24.

Read the section on cerebrospinal fluid (CSF) up to the Homeostatic Imbalance headline (p. 465).

• You’ll need to learn the route that the cerebrospinal fluid travels through the CNS. That information can be found in the lecture outline, in the lecture slides, and on this figure.
• See Art-Labeling Activity for Marieb Fig. 12.26.

Read the section on the blood-brain barrier (p. 467).

• You should know what creates the blood-brain barrier and why it is significant.
• You should also know something about the kinds of molecules that the barrier is permeable to versus those that it is impermeable to.
  • This should be review from Bio Principles.

Read the section called “Gross Anatomy and Protection” (pp. 470-472).

• Make sure you understand Marieb Fig. 12.29a (with the exception of the conus medullaris, the cauda equina and the filum terminale; those aren’t important.)

Read the introduction to cross-sectional anatomy (p. 472) and section called “Gray Matter and Spinal Roots” (pp. 472-473).

• Download the file Lecture Art: Spinal Cord Cross-Section.
  • When I teach the spinal cord in class, I spend the lecture drawing that picture and systematically going through it, adding layer upon layer of detail. Have a copy of that nearby as you read.
  • Note: it’s based on Martini Fig. 13-5a. I’ve included both labeled and unlabeled versions of the original for you to play with.
• The information that I’ve drawn on the spinal cord handout is explained in this section. Make sure that it makes sense to you.
• See Art-Labeling Activities for Marieb Fig. 12.31a and Fig. 12.31b.
• The next section (on white matter) deals with the tracts that convey impulses up and down the spinal cord. Due to time restraints, I don’t cover this in class, but please do understand that nerve impulses are not just carried along a horizontal plane, but vertically as well.

Read the introduction to the PNS (p. 491).

• We’re now out of the CNS (brain and spinal cord) and into the rest of the nervous system.
• This is depicted by the yellow boxes in Marieb Fig. 13.1.
  • This is review from Chapter 11, so hopefully it looks familiar.

Read the section on sensory receptors (pp. 491-492), up to (but not including) the section on classification by structural complexity.

• This section is fairly self-explanatory.
  • Receptors are classified by where they are found and the type of stimulus to which they respond.
  • Make sure you know the terms (i.e., words in bold) associated with these receptor classes.

Read the section on the structure and classification of nerves and associated ganglia (pp. 498-499).

• Marieb Fig. 13.3b is important.
  • Note the similarity to muscle nomenclature (Marieb Fig. 9.2a). This will be covered in lab, as well.
• You don’t have to worry about the somatic afferent, somatic efferent, visceral afferent and visceral efferent fibers within the mixed nerves, but you should know what the individual terms somatic, visceral, efferent, and afferent mean individually.
  • Again, these terms should look familiar.
    • Efferent and afferent were introduced in Chapter 1, Marieb Fig. 1.4 (p. 9).
    • You’ve probably heard the word somatic before as well (somatic cells in Bio Principles, perhaps).
    • Anatomically speaking, somatic refers to the body wall and limbs, and it is the opposite term to visceral, which refers to internal organs (inside of a body cavity).
• I don’t cover nerve regeneration, but nerves can perform a limited amount of regeneration if they are severed. This is, in part, mediated by the Schwann cells.

Read the section on the cranial nerves up to, but not including, Marieb Table 13.2 (pp. 500-501).

• Use the lecture outline to see what I cover in class for the cranial nerves. In general, you should learn the following:
  • the names and numbers of the twelve cranial nerves;
  • whether they are sensory or mixed;
    • There are no purely motor cranial nerves; they all contain a few proprioceptor afferent fibers.
  • their general function (very brief; no more than a few words – eye movement, controls chewing muscles, etc.);
  • for the trigeminal and the vestibulocochlear, you should learn the names and general functions of their divisions:
    • trigeminal: ophthalmic, maxillary, and mandibular divisions; and
    • vestibulocochlear: vestibular and cochlear nerves.
  • All cranial nerves serve head/neck structures, with the exception of the vagus nerve (X), which serves the major organs of the thorax and abdomen.
• There are several good mnemonic devices for learning the cranial nerves; the one in the book (“On occasion, our trusty truck acts funny – very good vehicle anyhow.”) works well.
  • In class, I use “Oh, oh, oh! To touch and feel very green vegetables! AH!” – where the final “AH!” stands for both the accessory and hypoglossal.
  • If you search online, you can occasionally dig up some pretty filthy ones, too.
• See this website from the Yale University School of Medicine on the cranial nerves.
• Note: this material is also covered on the lab exam, so you’ll be learning it once but using it for two purposes (lecture and lab).

Read the section on the general features of spinal nerves (pp. 508-509).

• Pay attention to how the nerves branch and what they are called.
  • Specifically, look how the spinal nerve branches into the dorsal ramus, the ventral ramus and the ramus communicantes.
    • dorsal ramus = turns posteriorly and innervates the back
    • ventral ramus = projects laterally to the body wall and limbs
    • rami communicantes = turn anteriorly and innervates the visceral organs (thoracic region only)
  • The sympathetic ganglion that you see on those figures will return in the ANS.
  • See this altered version of Marieb Fig. 13.7b for a summary.
  • See animation – Distribution of spinal routes.
    • Lots of spelling mistakes!
  • You do not have to learn the names of the spinal nerves or how many there are in each region of the spinal cord. Just appreciate the fact that their naming scheme is similar to that of the vertebrae (cervical, thoracic, etc.).

Read the first two paragraphs of the section on innervation of specific body regions (pp. 509-510).

• The purpose of these paragraphs is for you to understand what a plexus is.
• There are four major plexuses (cervical, brachial, lumbar and sacral).
  • Just look at them in the figures (Marieb Fig. 13.6; even better on Martini Fig. 13-9).
  • See 3D Rotate video clip – Major Nerves and Plexuses.
• You should know the major nerves that arise from these plexuses. They aren’t critically important in this course, but you will very likely encounter them in allied health courses you may take down the road. A couple may come up in A&P2 as well.
  • cervical plexus = mostly cutaneous nerves; phrenic nerve
    • The phrenic nerve innervates the diaphragm; comes up again in the respiratory system.
  • brachial plexus = axillary, musculocutaneous, median, ulnar, and radial nerves
    • See 3D Rotate video clip – Brachial Plexus.
  • lumbar plexus = femoral and obturator nerves
  • sacral plexus = tibial and sciatic nerves
    • See 3D Rotate video clip – Lumbosacral Plexus.
    • Trivia: the sciatic nerve is the largest and thickest nerve in the body.
    • Sciatica is a painful condition caused by injury to the sciatic nerve, often from falls or a herniated disc.

Read the section on the reflex arc and the components of a reflex arc (pp. 521-522).

• Once you’ve read this once, just concern yourself with the information in Marieb Fig. 13.14.
  • I expect that, by now, you are able to tie together things like the type of sensory receptor being stimulated, how nerve impulses are generated and conducted along the axons of the afferent fibers, the pathway towards the spinal cord, where the cell body of the sensory neuron is located, where it synapses in the spinal cord, how nerve impulses are conveyed from the spinal cord to the spinal nerves, what the effector organs are, and in this case, how skeletal muscle would respond (excitation-contraction coupling, etc.).
  • In short, you need to be able to tie together the anatomy and the physiology, using all of the vocabulary words and principles that you’ve learned over two semesters (Bio Principles and A&P1). This is where we come full circle with what we covered back in Preview and Review with structure-function relationships.
• In a perfect world, we would pay proper respect to the different types of spinal reflexes. But time is short, so just make sure you understand what a reflex arc is.
• Remember: it’s easy to envision a reflex as pulling your hand away from a hot stove, but there are many visceral reflexes that you will encounter in A&P2. An example of a visceral reflex would be secretion of gastric juice or contraction of intestinal smooth muscle as food moves along the digestive tract. Sure, this isn’t as dramatic as the painful, flesh-searing jolt that elicits a stream of expletives and tears, but it’s still a reflex.

Read the introduction to the ANS, including the sections on the comparison of the somatic and autonomic nervous systems and the ANS divisions (pp. 533-535).

• Neurons that release ACh are called cholinergic neurons.
• Neurons that release epinephrine or norepinephrine (NE) are called adrenergic neurons.
  • Epinephrine is also called adrenaline. It is released by sympathetic tissue in the adrenal medulla.
  • Epinephrine (and the adrenal medulla itself) will have important consequences on the cardiovascular system in A&P2.

Read the introduction to ANS anatomy (bottom of p. 535)

• Marieb Fig. 14.3 is helpful.

Read the first paragraph in the section titled Parasympathetic (Craniosacral) Division (p. 536).

• Here’s a summary:
  • The preganglionic cell body resides in the brain or sacral region of the spinal cord.
  • Its axon is very long and synapses with the postganglionic neuron close to the effector organ.
  • The postganglionic cell body resides in a terminal ganglion.
  • The preganglionic neuron stimulates the postganglionic neuron by releasing ACh (therefore, the preganglionic neuron is cholinergic).
  • The postganglionic axon is very short and it is also a cholinergic neuron.
• See animation – Distribution of Parasympathetic Fibers.
  • There is quite a bit of unnecessary anatomy here. Just pay attention to the long preganglionic axons and short ganglionic axons.
  • If the animation stops and you don’t know what to do, click the flashing red arrow in the bottom right corner.

Read the introductory section titled Sympathetic (Thoracolumbar) Division (pp. 538-540).

• There’s a great deal of unnecessary detail in this section. Here’s the important stuff:
  • In the sympathetic division, the preganglionic cell body resides in either the thoracic or lumbar regions of the spinal cord.
  • Its axon is very short and synapses with the postganglionic neuron close to the spinal cord.
  • The postganglionic cell body resides in a sympathetic ganglion (sometimes called a paravertebral or collateral ganglion).
  • The preganglionic neuron is cholinergic (releases ACh).
  • The postganglionic axon is very long and this cell is an adrenergic neuron (it releases either epinephrine or norepinephrine).
• See animation – Distribution of Sympathetic Fibers.
  • Again, lots of unnecessary anatomy here. Just pay attention to the short preganglionic axons and long ganglionic axons.
  • If the animation stops and you don’t know what to do, click the flashing red arrow in the bottom right corner.

Read the section on the ANS neurotransmitters and their receptors (p. 543).

• I want you to read this section just to gain an understanding of cholinergic and adrenergic receptors.
• Understand that ACh and epinephrine/norepinephrine do not consistently activate or inhibit their postsynaptic cells. Their effects depend on the receptors on the postsynaptic cells.
• Here’s a breakdown of the types of receptors:
  • cholinergic receptors:
    • nicotinic receptors
      • found on skeletal muscle, all ganglionic neurons, and on target cells in the adrenal medulla
      • always stimulatory
    • muscarinic receptors
      • found on effector cells of postganglionic neurons
      • can be stimulatory or inhibitory
  • adrenergic receptors:
    • two types: α and β receptors
    • there are several subtypes of each
    • they can be stimulatory or inhibitory, depending on the subtype
    • β receptors may come up in the cardiovascular system in A&P2