Biology: The Dynamic Science, Ch. 40 (pg 951-963)

Which of the two autonomic nervous system divisions predominates in the following scenarios? 1. You are hiking on a trail and suddenly a bear appears in your path. 2. It is a hot, sunny day.

1. Sympathetic nervous system; this is the classic "fight or flight" scenario for this autonomic nervous system division. 2. Parasympathetic nervous system.

In echinoderms, especially sea stars, the nervous system is a modified nerve net, with some neurons organized into nerves, bundles of axons enclosed in connective tissue and following the same pathway. What are two nerve structures are in the echnioderms?

A /nerve ring/ surrounds the centrally located mouth, and a radial nerve branches to connect to nerve nets throughout each arm. If the /radial nerve/ serving an arm is cut, the arm can still move, but not in coordination with the other arms.

Muscle spindles

A bundle of small, specialized muscle cells wrapped with the dendrites of afferent neurons.

What is the reticular formation?

A complex network of interconnected neurons that runs through the length of the brain stem, connecting to the thalamus at the anterior end and to the spinal cord at the posterior end. Most incoming sensory input goes to the reticular formation, which integrates the information and then sends signals to other parts of the CNS. pneumonic: the reticular formation is involved in motivation and alertness. Use "tickle" as your mnemonic. If you (or your roommate) were asleep and someone tickled you, your reticular formation would wake you up.

limbic system

A functional network formed by parts of the thalamus, hypothalamus, and basal nuclei, along with other nearby gray-matter centers—the amygdala, hippocampus, and olfactory bulbs—sometimes called the "emotional brain."

What is the neural tube?

A hollow tube in vertebrate embryos that develops into the brain, spinal cord, spinal nerves, and spinal column.

Distinguish between a nerve net, nerves, and nerve cords.

A nerve net is a loose meshwork of neurons organized in a radial pattern that reflects the radial symmetry of the animal in which it is found. Nerves are bundles of axons surrounded by connective tissue. Nerve cords are bundles of nerves.

hippocampus

A neural center located in the limbic system that helps process explicit memories for storage Pneumonic: involved in memory. Use "hippo-compass": picture a hippo who is lost and can't remember how to get home, so he's using a compass.

blood-brain barrier

A specialized arrangement of capillaries in the brain that prevents most substances dissolved in the blood from entering the cerebrospinal fluid and thus protects the brain and spinal cord from viruses, bacteria, and toxic substances that may circulate in the blood.

brain stem

A stalklike structure formed by the pons and medulla, along with the midbrain. It connects the forebrain ("higher centers") with the spinal cord. All but two of the twelve pairs of cranial nerves also originate from the brain stem. These higher centers, which make up most of the mass of the brain in humans, are generally referred to as the telencephalon (cerebrum).

cerebral cortex

A thin outer shell of gray matter covering a thick core of white matter within each hemisphere of the brain; the part of the forebrain responsible for information processing and learning. The /basal nuclei/, consisting of several regions of gray matter, are located deep within the white matter.

Anatomical analysis and experimental physiological studies have shown the changes that have occurred in the brain regions and brain size of vertebrates during evolution: What has changed with regards to brain regions?

Brain regions: Most vertebrates have the same number of brain divisions, suggesting that much of the organization of the brain arose at or soon after the origin of vertebrates. The exception is the absence of a cerebellum in agnathans (jawless vertebrates)

Anatomical analysis and experimental physiological studies have shown the changes that have occurred in the brain regions and brain size of vertebrates during evolution: What has changed with regards to brain size? Which animals have the largest brains?

Brain size: Looking across the vertebrate phylogenetic tree, brain size varies approximately 30-fold for a given body size. For example, most bony fishes have larger brains for the same body size than agnathans, ditto for frogs versus salamanders; reptile brains are two to three times larger than the brains of most amphibians of the same body size; and the brains of both birds and mammals are 6-10 times larger than the brains of reptiles of the same body size. Among mammals, primates and cetaceans have the largest brains for their body size, whereas marsupials, nonplacental mammals, insectivores, and rodents have the smallest brains for their body size.

What is cephalization?

Cephalization is the formation of a distinct head region containing ganglia, which form a major central control center or brain, and major sensory structures. Cephalization is found in more complex invertebrates and in all vertebrates.

What are nerve nets? What animals have them?

Cnidarians and echinoderms are radially symmetrical animals with body parts arranged regularly around a central axis, like the spokes of a wheel. Their nervous systems, called nerve nets, are loose meshes of neurons organized within that radial symmetry. Nerve nets are a simple nervous system that coordinates responses to stimuli but has no central control organ, or brain.

Ascending Reticular Formation (reticular activating system)

Contains neurons that convey stimulatory signals via the thalamus to arouse and activate the cerebral cortex. It is responsible for the sleep-wake cycle; depending on the level of stimulation of the cortex, various levels of alertness and consciousness are produced. Lesions in this part of the brain stem result in coma.

What is the difference between gray matter and white matter?

Gray matter consists of nerve cell bodies and dendrites; white matter consists of axons, many of them surrounded by myelin sheaths.

Grey Matter vs White Matter

Gray matter, consists of nerve cell bodies and dendrites White matter, consisting of axons, many of them surrounded by myelin sheaths (The myelination of the axons gives white matter its color.)

What are the neuronal chain of events for a patellar tendon reflex?

In a patellar tendon reflex (knee-jerk reflex), a tap on the tendon just below the knee causes a sequence of events that causes the leg to kick. The tap stimulates afferent neurons that make excitatory connections to efferent neurons with a single synapse, and to inhibitory interneurons. Excited efferent neurons stimulate the flexor muscle of the leg to contract. The inhibitory interneurons connect to efferent neurons that lead to the extensor muscle of the leg; those neurons inhibit that muscle from contracting.

In humans, each cerebral hemisphere is divided by surface folds into (3)

In humans, each cerebral hemisphere is divided by surface folds into frontal, parietal, temporal, and occipital lobes

Nerve cords

Nerve cords—bundles of nerves—extend from the brain to the rest of the body.

What are the Two Other Motor Control Areas of the Cerebral Cortex:

Premotor cortex and the posterior parietal cortex The premotor cortex of the frontal lobe controls skeletal muscles in coordinating complex movements. It's guided by sensory input received and processed by the posterior parietal cortex of the parietal lobe. Damage to either of these two motor areas results in an inability to process complex sensory information to carry out movements in space, such as working with tools.

descending reticular formation

Receives information from a variety of sources including the hypothalamus and connects with interneurons in the spinal cord that control skeletal muscle contraction, thereby controlling muscle movement and posture. The reticular formation *filters* incoming signals, helping to discriminate between important and unimportant ones. Such filtering is necessary because the brain is unable to process every one of the signals from millions of sensory receptors. For example, the action of the reticular formation enables you to sleep through many sounds but waken to specific ones, such as a cat meowing to be let out or a baby crying

A key evolutionary development in invertebrates is a trend toward ____

Some neurons are concentrated into a functional cluster called a ganglion. A key evolutionary development in invertebrates is a trend toward *cephalization*, the formation of a distinct head region containing ganglia that constitute a brain, the control center of the nervous system that integrates major sensory input with motor output.

In mammals, 31 pairs of ______ nerves carry signals between the spinal cord and the body trunk and limbs, and 12 pairs of _________ nerves connect the brain directly to the head, neck, and body trunk.

Spinal Cranial

Sympathetic and parasympathetic preganglionic neurons secrete the neurotransmitter: Most sympathetic postganglionic neurons secrete the neurotransmitter: Most parasympathetic postganglionic neurons secrete:

Sympathetic and parasympathetic preganglionic neurons secrete the neurotransmitter acetylcholine, which binds to receptors on the postganglionic neuron. Most sympathetic postganglionic neurons secrete the neurotransmitter norepinephrine, which binds to receptors on cells of the effector organ. Most parasympathetic postganglionic neurons secrete acetylcholine, which binds to receptors on cells of the effector organ.

somatic nervous system (what does it control? With what neurons?)

The *somatic nervous system( controls body movements that are primarily conscious and voluntary. Control's the body's skeletal muscles. Its neurons, called *motor neurons*, carry efferent signals from the CNS to the skeletal muscles.

sympathetic nervous system

The *sympathetic nervous system* predominates in situations involving stress, danger, excitement, or strenuous physical activity. Signals from the sympathetic division increase the force and rate of the heartbeat, raise the blood pressure by constricting selected blood vessels, dilate air passages in the lungs, induce sweating, and open the pupils wide.

afferent division

The afferent division of the PNS carries signals to the CNS

amygdala

The amygdala routes information about experiences that have an emotional component through the limbic system Pneumonic: involved in your fear responses. Picture a scary wig (rhymes with "myg") with dollars in the hair (similar to "dala").

The reticular formation has two parts:

The ascending and descending reticular formation

autonomic nervous system With what muscle/glands? What does it control? What are the two divisions and how do they work together?

The autonomic nervous system consists of nerves to smooth muscle, cardiac muscle, exocrine glands, and some endocrine glands. It controls largely involuntary processes such as blood circulation, secretion by sweat glands, many functions of the reproductive and excretory systems, and contraction of smooth muscles in all parts of the body. The autonomic nervous system has two divisions, the *sympathetic nervous system* and the *parasympathetic nervous system*, which are always active and have opposing effects on the organs they affect, thereby enabling precise control. For example, in the circulatory system, sympathetic neurons stimulate the force and rate of the heartbeat, and parasympathetic neurons inhibit these activities. These opposing effects control involuntary body functions precisely.

basal nuclei (where, what is, damage does?)

The basal nuclei are gray-matter centers that surround the thalamus on both sides of the brain They moderate voluntary movements directed by motor centers in the cerebrum. Damage to the basal nuclei can affect the planning and fine-tuning of movements, leading to stiff, rigid motions of the limbs and unwanted or misdirected motor activity, such as tremors of the hands and inability to start or stop intended movements at the intended place and time. Parkinson disease, in which affected individuals exhibit all of these symptoms, results from degeneration of centers in and near the basal nuclei.

What is the blood-brain barrier, and what is its function?

The blood-brain barrier is a distinct separation between the blood and the brain resulting from tight junctions between the epithelial cells forming the walls of the capillaries in the brain. The blood-brain barrier regulates exchanges between blood and the brain, in particular preventing most dissolved substances from entering the cerebrospinal fluid, thereby protecting the brain and spinal cord from viruses, bacteria, and toxic substances that may be in the blood.

What is meninges and cerebrospinal fluid?

The brain and spinal cord are surrounded and protected by three layers of connective tissue called *meninges*, and by *cerebrospinal fluid*, which circulates through the ventricles of the brain, through the central canal of the spinal cord, and between two of the meninges. The fluid cushions the brain and spinal cord from jarring movements and impacts, and it both nourishes the CNS and protects it from toxic substances.

What is the function of the brain stem?

The brain stem regulates a number of the body's vital housekeeping functions without conscious involvement or control by the cerebrum, including heart and respiration rates, blood pressure, constriction and dilation of blood vessels, coughing, and reflex activities of the digestive system.

Distinguish the structure and functions of the cerebellum from those of the cerebral cortex.

The cerebellum is an outgrowth of the pons, but it is structurally and functionally separate from the brain stem. The cerebellum has extensive connections with other parts of the brain, through which it receives sensory inputs from receptors in muscles and joints, from balance receptors in the inner ear, and from the receptors of touch, vision, and hearing. The cerebellum integrates the various sensory signals and compares them with signals from the cerebrum that control voluntary body movements. Information flow from the cerebellum to the cerebrum, brain stem, and spinal cord modifies and fine-tunes movements of the body. In humans, the cerebellum also is involved in the learning and memory of motor skills. The cerebral cortex is a thin, folded layer of gray matter that forms the surface of the cerebrum. The cerebral cortex contains sensory areas that receive and integrate sensory information of many kinds, including touch, pain, temperature, pressure, hearing, vision, smell, and taste. It also contains motor areas that are involved in controlling body movements and position, and association areas, which integrate information from the sensory areas and send responses to the motor area. Most higher functions of the human brain, including critical thinking, abstract thought, musical ability, and aspects of personality, involve activities of many regions of the cerebral cortex.

The efferent division of the PNS is further subdivided into the:

The efferent division of the PNS is further subdivided into the somatic nervous system and the autonomic nervous system

The pathways of the autonomic nervous system have two neurons in series. What are these two neurons?

The first neuron, the *preganglionic neuron*, has its dendrites and cell body in the CNS, and its axon extends to a ganglion in the PNS. There, it synapses with the dendrites and cell body of the second neuron in the pathway, the *postganglionic neuron*. The axon of the second neuron extends from the ganglion to the effector carrying out the response.

forebrain (what it is/sections/controls)

The forebrain of the embryo eventually gives rise to the *cerebrum* (or adult telencephalon) and the *thalamus and hypothalamus* of the adult. The /cerebrum/ is the largest part of the brain. It controls higher functions such as thought, memory, language, and emotions, as well as voluntary movements. The /thalamus/ is a center that receives sensory input and relays it to the regions of the cerebral cortex concerned with pertinent motor responses, and the /hypothalamus/ is the primary center for homeostatic control over the internal environment.

frontal lobes

The frontal lobes are responsible for voluntary motor activity, expressing language, and elaboration of thought. pneumonic: the frontal lobe is where complex thinking occurs. Use "front door" as your mnemonic. Put the front door on your forehead and put Einstein (complex thinker) behind the door.

What's a reflex? And a classic example of the stretch reflex?

The gray matter of the spinal cord also contains pathways involved in *reflexes*, programmed movements that take place without conscious effort An example is the patellar tendon reflex (commonly called the knee-jerk reflex), in which a tap to the tendon just below the knee cap (patella) causes the leg to kick. The patellar tendon reflex is the classic example of the *stretch reflex*. The main purpose of the patellar tendon reflex is to react to added loads that stretch the muscles of the leg. During normal activity, it serves to maintain balance should anything cause an unexpected load on the quadriceps muscle, such as a stumble or a trip.

hypothalamus (where? What glands in it? What does it do?)

The hypothalamus is a region of the brain located in the floor of the cerebrum that contains clusters of neurons known as /nuclei/. Suspended just below it and connected to it by a stalk of tissue is the *pituitary gland*, consisting of two fused lobes, the anterior pituitary and the posterior pituitary, which release hormones. The hypothalamus regulates basic homeostatic functions of the body both directly and through the release of hormones. Some nuclei in the hypothalamus set and maintain body temperature, most notably by regulating basal metabolic rate Pneumonic: the hypothalamus regulates many of the body's metabolic processes, thirst, hunger and body temperature. Use "hypo- the-llamas" as your mnemonic. Picture a hypo spraying two thirsty llamas with water to quench their thirst and cool them down.

hindbrain (what it is/sections/controls)

The largest and most complicated region of the brain, includes the *cerebellum, pons, medulla* etc The hindbrain subdivides and eventually gives rise to the /cerebellum/, which integrates sensory signals from the eyes, ears, and *muscle spindles* with motor signals from the /telencephalon/, and the /pons/ The hindbrain also gives rise to the medulla oblongata (commonly shortened to medulla), which controls many vital involuntary tasks such as respiration and blood circulation. Pneumonic for medullua: The medulla regulates the autonomic activity of the heart and lungs. Use medals as your mnemonic and stick the medals in a bloody heart and lungs. Or picture an Olympic athlete wearing gold medals around her neck and covering her heart and lungs.

midbrain (what it is/sections/controls)

The midbrain gives rise to the adult midbrain, which, with the pons and the medulla, constitutes the *brain stem*. The midbrain has centers for coordinating reflex responses (involuntary reactions) to visual and auditory (hearing) input and relays signals to the telencephalon.

occipital lobe

The occipital lobes perform initial processing of visual input. Pneumonic: Occipital sounds like Optical. The occipital lobe processes visual information

parasympathetic nervous system

The parasympathetic nervous system, in contrast, predominates during quiet, lowstress situations, such as while relaxing. During relaxation the influence of the parasympathetic division reduces the effects of the sympathetic division, such as rapid heartbeat and elevated blood pressure, and activities such as digestion predominate.

parietal lobes

The parietal lobes are mainly responsible for receiving and processing sensory input. pneumonic: processes sensory information. Use a "piranha" fish as your mnemonic. The piranha bites you on the top of the head (where the parietal lobe is located). That's a sensation the parietal lobe would process.

temporal lobes

The temporal lobes receive auditory input. pneumonic: the temporal lobe is where auditory processing occurs. Use "tempo" as your mnemonic and picture a metronome above your ear (where the temporal lobe is located)

thalamus (what does it do?)

The thalamus forms a major switchboard that receives sensory information and relays it to the regions of the cerebral cortex concerned with motor responses to sensory information. Part of the thalamus near the brain stem cooperates with the reticular formation in alerting the cerebral cortex to full wakefulness, or in inducing drowsiness or sleep pneumonic: the thalamus relays information from the body to different areas of the brain for processing. Picture Hal and Amos as traffic cops.

corpus callosum

Thick axon bundles, forming a structure called the corpus callosum connect the two cerebral hemispheres and coordinate their functions. pneumonic: the corpus callosum connects the two hemispheres. Thus, the corPLUS CalloSUM.

The two main areas of the cerebral cortex specialized for language are:

Wernicke's area in the parietal lobe which controls language comprehension Broca's area in the frontal lobe, which controls speech function They are usually present on only one side of the brain—in the left hemisphere in 97% of the human population Pneumonic Broca: Broca's area is the area of the brain responsible for producing speech. If it is damaged, you can understand what someone says, but your speech is disjointed. In other words, *"Broca's speech is broken"* or "Broca's banter is broken". Pneumonic Wernicke's area: Wernicke's area is responsible for the comprehension of speech. If you have an aphasia in this area of the brain you are unable to understand and respond to what people are saying to you. In other words, *"Wernicke's comprehension is crappy"*

somatosensory cortex

area at the front of the parietal lobes that registers and processes body touch, pain, temperature, pressure and movement sensations

The sensory, motor, and language areas comprise about one half of the cerebral cortex. The other areas, called ________, are involved in higher functions

association areas

central nervous system consists of

brain and spinal cord

peripheral nervous system consists of

consisting of neurons connecting the CNS and the other parts of the body

Cerebellum (what is and function)

coordination of voluntary movements and balance The portion of the brain that receives sensory input from receptors in muscles and joints, from balance receptors in the inner ear, and from the receptors of touch, vision, and hearing. pneumonic: involved in helping you maintain balance. Picture a tight walker using bells for balance. Or picture your favorite athlete trying to balance a bell on his/her head.

efferent devision

efferent division of the PNS carries signals from the CNS to the muscles and glands,

These trends toward cephalization and bilateral symmetry are seen in

flatworms, arthropods, and mollusks:

limbic association cortex

motivation, emotion, memory

prefrontal association cortex

planning for voluntary activity; decision making; personality traits

Scanning techniques such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) allow

researchers to identify the functions of specific brain regions in noninvasive ways. For a PET scan of the brain, an individual is given a dose of radioactive glucose. When an area of the brain becomes active, more glucose is needed there to be metabolized to provide energy. Therefore, the amount of radioisotope that becomes localized to a particular area correlates with the amount of brain activity in that area. The scanner detects the radioactivity of the glucose, and a computer converts the results into multicolored two- or three-dimensional images.

olfactory bulbs

smell Relay inputs from odor receptors to both the cerebral cortex and the limbic system. The olfactory connection to the limbic system may explain why certain odors can evoke particular, sometimes startlingly powerful emotional responses. pneumonic: think of smelly factory

synaptic plasticity

the ability of a synapse to change over time through use or disuse The process by which a neuron's dendrites can change in shape and extent, thereby establishing new synaptic connections with other neurons.

The peripheral nervous system is subdivided into two:

the afferent division and the efferent division

plasticity

the brain's ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience The basis of plasticity, in part, is the formation of new synaptic connections between neurons (not the addition of new neurons) in response to experience.

Early in embryonic development, the anterior part of the neural tube enlarges into three distinct regions:

the forebrain, midbrain, and hindbrain

Primary Motor Cortex of the Cerebral Cortex: primary motor cortex

the section of the frontal lobe responsible for voluntary movement The primary motor cortex of the cerebral cortex runs in a band just in front of the somatosensory cortex, and is involved in coordinating skeletal muscles for voluntary movements.