Module 4 - Biol 246

- Like the cerebrum, the cerebellum consists of two hemispheres with an outer grey cortex (containing more neurons than the rest of the brain) and inner white matter with nuclei. - The cerebellum is required for movements that are smooth and goal-directed, such as touching your finger to your nose, bringing a fork of food to your mouth, or finding keys by touch in your pocket or purse. - The cerebellum is also required for maintaining posture and balance and for learning new movement activities, and it contributes to autonomic function and cognitive skills.

The Cerebellum, which is part of the Metencephalon... What are some of its characteristics/functions?

Metencephalon

The Pons and Cerebellum make up what?

Limbic System

The ________ _________ in humans is a center for basic emotional drives.

Medulla Oblongata

The ____________ contains groupings of neurons required for the regulation of breathing and of cardiovascular responses; hence, they are known as the vital centers.

Amygdaloid Body

The _______________ ________ of the Limbic System is involved in the improvement of memory when the memory has an emotional content.

Relative Refractory Period

"During the time that the Na+ channels are in the process of recovering from their inactivated state and the K+ channels are still open from the first action potential, yet a strong enough stimulus can still produce a second action potential."

Cholinergic Neurons

Acetylcholine is a neurotransmitter that can be either excitatory or inhibitory. Neurons that use Acetylcholine as a neurotransmitter are called __________ neurons.

Hippocampus; As a result, stress can promote the storage of emotionally strong memories but hinder the retrieval of those memories and working memory. In this regard, researchers have demonstrated that people with post-traumatic stress disorder (PTSD) often have atrophy of the hippocampus.

Although strong emotions enhance memory encoding within the amygdaloid body, stress can impair memory consolidation by the ___________, as well as impair the cognitive functions and working memory performed by the prefrontal cortex.

Retrograde Transport

Axonal transport in the opposite direction—that is, along the axon and dendrites toward the cell body—is known as?

Divergence

Because axons can have collateral branches, _____________ of neural pathways can occur. That is, one axon can make synapses with a number of other neurons, and by that means either stimulate or inhibit them.

Chemically regulated (or ligand-regulated) gates

Binding of neurotransmitter ligands to their respective receptor proteins causes ion channels to open in the postsynaptic membrane. The gates that regulate these channels, therefore, can be called ________ _________ _________ because they open in response to the binding of a chemical ligand to its receptor in the postsynaptic plasma membrane.

Lateralization

The term ___________ refers to the specialization of function of each cerebral hemisphere.

Corpus Callosum; Note:

The two hemispheres of the brain communicate with each other via the _______ ________, a large tract composed of about 200 million fibers.

Funiculi; Funiculi are columns of white matter in the spinal cord.

The white matter of the spinal cord is composed of ascending and descending fiber tracts. These are arranged into six columns of white matter called __________.

The glycine and GABA receptors are ligand-gated ion channels that, like the nicotinic ACh receptor, open when the receptor binds to its neurotransmitter ligand. When GABA and Glycine bind to their respective receptors, they open channels for Cl− that hyperpolarize the postsynaptic membrane and produce an IPSP

There are two inhibitory neurotransmitters in the CNS: GABA and Glycine. How do they work as inhibitors?

1. GABA 2. Glycine

There are two inhibitory neurotransmitters in the CNS: what are they?

Leakage Channels

There are two types of channels for K+. One type of K+ channel is gated, and the gates are closed at the resting membrane potential. The other type of K+ channel is not gated, and the gates are always open. These are often called ____________ channels.

Amnesia can result from damage to the... 1. Temporal Lobe 2. Hippocampus 3. Thalamus Mnemonic: THT

Clinical studies of amnesia (loss of memory) suggest that several different brain regions are involved in memory storage and retrieval. What are those 3 regions?

Arcuate Fasciculus

"A bundle of axons that connects Wernicke's area with Broca's area; damage causes conduction aphasia."

Leakage Channels

"A channel that is always open."

Schwann Cells

"A glial cell of the PNS, form myelin sheaths around peripheral axons."

Microglia

"A glial cell that migrates through the CNS and phagocytosis foreign and degenerated material"

Satellite Cells

"A glial cell that supports neuron cell bodies within the ganglia of the PNS."

Oligodendrocytes

"A glial cells of the CNS, which form myelin sheaths around axons of the CNS."

Absolute Refractory

"A period immediately after an action potential when another action potential cannot occur."

Reflex Arc

"A relatively direct connection between a sensory neuron and a motor neuron that allows an extremely rapid response to a stimulus, often without conscious brain involvement."

Anterograde Transport

"A type of axonal transport that occurs from the cell body to the axon and dendrites."

Spatial Summation

"Integration by a postsynaptic neuron by inputs from multiple sources." "Occurs due to the convergence of terminal boutons from different presynaptic axons (up to a thousand in some cases) on the dendrites and cell body of a single postsynaptic neuron."

Temporal Summation

"Occurs when one or more presynaptic neurons transmit impulses in rapid-fire order to a postsynaptic neuron."

Diencephalon

"The ________________ is the part of the forebrain that contains the epithalamus, thalamus, hypothalamus, and part of the pituitary gland."

Synaptic Plasticity

"The ability of a synapse to change over time through use or disuse." "This is the ability of synapses to change in response to recent activity."

Serotonin-Specific Reuptake Inhibitors (SSRIs)... - The role of serotonin in the regulation of mood and emotion is currently exploited by the action of the antidepressant drugs Prozac, Paxil, Zoloft, Lexapro, and Luvox, which act as serotonin-specific reuptake inhibitors (SSRIs). - The SSRI drugs bind at the same site as serotonin does to the serotonin transporter (SERT) proteins in the presynaptic axon membrane. SSRIs thereby compete with serotonin at this site and reduce the ability of SERT to clear serotonin from the synaptic cleft. - This increases the ability of serotonin to stimulate its receptors in the postsynaptic membrane, an ability that aids in the treatment of depression as more serotonin is produced.

"These are antidepressant drug agents used in the treatment of depression."

1. Nucleus 2. Tract

1. A cluster of cell bodies in the CNS is usually referred to as a ___________. 2. A bundle of axons in the CNS is called a _______.

1. Motor Control 2. Somatosensory

1. The precentral gyrus, which is involved in _______ ______, is located in the frontal lobe just in front of the central sulcus. The cell bodies of the interneurons located here are called upper motor neurons because of their role in muscle regulation. 2. The postcentral gyrus, which is located behind the central sulcus in the parietal lobe of each hemisphere, contains the _____________ cortex. This is the primary area responsible for the perception of somesthetic sensations—sensations arising from cutaneous, muscle, tendon, and joint receptors.

1. When the axon membrane has been depolarized to a threshold level by stimulating electrodes—gated Na+ channels open and the membrane becomes more permeable to Na+. 2. This permits Na+ to enter the axon by diffusion, which further depolarizes the membrane (makes the inside less negative, or more positive). 3. The explosive increase in Na+ permeability results in a rapid reversal of the membrane potential in that region from −70 mV to +30 mV. At that point the channels for Na+ close, causing a rapid decrease in Na+ permeability. 4. Also at this time, as a result of a time-delayed effect of the depolarization, voltage-gated K+ channels open and K+ diffuses rapidly out of the cell. 5. Because K+ is positively charged, the diffusion of K+ out of the cell makes the inside of the cell less positive, or more negative, and acts to restore the original resting membrane potential of −70 mV. This process is called repolarization. 6. As the Na+ channels are becoming inactivated, the gated K+ channels open and the membrane potential moves toward the K+ equilibrium potential. This outward diffusion of K+ repolarizes the membrane. Actually, the membrane potential slightly overshoots the resting membrane potential, producing an after-hyperpolarization as a result of the continued outward movement of K+. Note: The Na+/K+ pumps are constantly working in the plasma membrane. They pump out the Na+ that entered the axon during an action potential and pump in the K+ that had left. Remember that only a relatively small amount of Na+ and K+ ions move into and out of the axon during an action potential. This movement is sufficient to cause changes in the membrane potential during an action potential but does not greatly affect the concentrations of these ions.

Describe whats happens during an Action Potential...

Absolute: Movement of too many K+ ions during repolarization, plus the inactivation of Na+ ion channels. Refractory: Movement of too many K+ ions during repolarization.

Difference between Absolute And Relative Refractory Periods?

Depolarization of a dendrite or cell body is excitatory. Hyperpolarization is inhibitory, in terms of their effects on the production of nerve impulses.

Difference between Depolarization and Hyperpolarization?

1. Neuroglia can divide mitotically 2. Neuroglia are much more abundant than neurons.

Difference between Neurons & Neuroglia?

Changes in Na+ and K+ diffusion change the membrane potential of a cell and produce an event called an action potential. Graded potentials travel by passive spread (electronic spread) to neighboring membrane regions. Action potentials are triggered by membrane depolarization to threshold. Graded potentials are responsible for the initial membrane depolarization to threshold.

Difference between an action potential and graded potential?

Monoamines

Dopamine, norepinephrine, and serotonin are examples of?

Agonists; Antagonists Example: For example, muscarine is an agonist of muscarinic ACh receptors.

Drugs that bind to and thereby activate receptor proteins are called _______, and drugs that bind to and thereby reduce the activity of receptor proteins are ___________.

Amygdaloid Body Note: The Amygdaloid Body of the Limbic System is involved in the improvement of memory when the memory has an emotional content.

Emotions influence memory, in some cases by strengthening, and in others by hindering, memory formation. The _______________ ________ is involved in the improvement of memory when the memory has an emotional content. This is illustrated by the observation that patients who have damage to both amygdaloid bodies lose the usual enhancement of memory by emotion.

Since the Medulla Oblongata is continuous with the pons superiorly and the spinal cord inferiorly, all of the descending and ascending fiber tracts that provide communication between the spinal cord and the brain must pass through the medulla oblongata. Also, the Medulla regulates respiratory and cardiovascular functions.

Function of the Medulla Oblongata?

Chemical Synapses work via the release of Neurotransmitters from presynaptic axon endings. These presynaptic endings, called terminal boutons, are separated from the postsynaptic neurons via synaptic clefts.

How do chemical synapses work?

Memory consolidation requires... 1. The activation of genes 2. The production of new proteins 3. The formation of new synapses - There is now evidence (in rodents) that memory consolidation in the hippocampus also requires glycogenolysis and lactate production in astrocytes at about the time of training.

How does Memory Consolidation occur? Memory Consolidation: The conversion of a short-term memory into a more stable long-term memory.

When an axon in a peripheral nerve is cut, the distal portion of the axon that was severed from the cell body degenerates and is phagocytosed by Schwann cells. The Schwann cells, surrounded by the basement membrane, then form a regeneration tube as the part of the axon that is connected to the cell body begins to grow and exhibit amoeboid movement. The Schwann cells of the regeneration tube are believed to secrete chemicals that attract the growing axon tip, and the regeneration tube helps guide the regenerating axon to its proper destination. Even a severed major nerve may be surgically reconnected—and the function of the nerve largely reestablished—if the surgery is performed before tissue death occurs.

How does a damaged axon regenerate?

Schwann cell can only form a myelin sheath around only one axon. Oligodendrocytes has extensions that form myelin sheaths around several axons.

How is the Myelin Sheath in the CNS different from the Myelin Sheath in the PNS?

Synaptic Inhibition

Hyperpolarizations produced by inhibitory neurotransmitters such as GABA and Glycine (by causing an inflow of Cl- ions into the cell) produce an event called _________ _________.

Absolute Refractory

If a second stimulus is applied during most of the time that an action potential is being produced, the second stimulus will have no effect on the axon membrane. The membrane is thus said to be in an ______ ________ period; it cannot respond to any subsequent stimulus.

Acetylcholine (ACh) is used as an excitatory neurotransmitter. Note: ACh may be either excitatory or inhibitory, depending on the organ involved.

Importance of Acetylcholine?

Forebrain

Important to note: - The diencephalon, together with the telencephalon (also called the cerebrum), constitutes the forebrain and is almost completely surrounded by the cerebral hemispheres. The third ventricle is a narrow midline cavity within the diencephalon.

Temporal Summation

In _______ _________, successively rapid bursts of activity from a single presynaptic axon can cause corresponding bursts of neurotransmitter release, resulting in successive waves of EPSPs (or IPSPs) that summate with each other as they travel to the initial segment of the postsynaptic neuron.

Long-Term Depression (LTD) Note: LTD is a related process involving the removal of AMPA receptors from the postsynaptic membrane.

In neurophysiology, ______ ______ __________ is an activity-dependent reduction in the efficacy of neuronal synapses lasting hours or longer following a long patterned stimulus.

Reticular Activating System (RAS)

In order to fall asleep, we must be able to "tune out" sensory stimulation that ascends to the cerebral cortex. Conversely, we awake rather quickly from sleep when the cerebral cortex is alerted to incoming sensory information. These abilities, and the normal cycles of sleep and wakefulness that result, depend upon the activation and inhibition of neural pathways that go from the pons through the midbrain reticular formation, an interconnected group of neurons. This constitutes an ascending arousal system known as the _________ _________ _________.

Reticular formation; Reticular Activating System Note: The RAS includes groups of cholinergic neurons (neurons that release ACh) in the brain stem that project to the thalamus; these neurons enhance the transmission of sensory information from the thalamus to the cerebral cortex.

In order to fall asleep, we must be able to "tune out" sensory stimulation that ascends to the cerebral cortex. Conversely, we awake rather quickly from sleep when the cerebral cortex is alerted to incoming sensory information. These abilities, and the normal cycles of sleep and wakefulness that result, depending upon the activation and inhibition of neural pathways that go from the pons through the midbrain _________ _________, an interconnected group of neurons. This constitutes an ascending arousal system known as the _________ ________ _________.

1. Nondeclarative (or implicit) Memory: Nondeclarative memory refers to memory of simple skills and conditioning (such as remembering how to tie shoelaces). 2. Declarative (or explicit) Memory: Declarative memory is memory that can be verbalized; it is subdivided into semantic (fact) and episodic (event) memory. (DESE)

Long-term memory is classified into 2 categories. What are they?

Mixed Nerves

Most cranial nerves are classified as ________ nerves. This term indicates that the nerve contains both sensory and motor fibers. Those cranial nerves associated with the special senses (e.g., olfactory, optic), however, consist of sensory fibers only.

PNS Neuroglia 1. Schwann cells, which form myelin sheaths around peripheral axons. 2. Satellite cells, which support neuron cell bodies within the ganglia of the PNS. CNS Neuroglia 1. Oligodendrocytes, which form myelin sheaths around axons of the CNS. 2. Microglia, which migrate through the CNS and phagocytose foreign and degenerated material; 3. Astrocytes, which help to regulate the external environment of neurons in the CNS; and 4. Ependymal cells, which are epithelial cells that line the ventricles (cavities) of the brain and the central canal of the spinal cord.

Name the types of Neuroglia/Glial Cells in the PNS and CNS?

2; 10

Of the 12 pairs of cranial nerves, ___ pairs arise from neuron cell bodies located in the forebrain and ___ pairs arise from the midbrain and hindbrain.

Convergence

Oppositely, a number of axons can synapse on a single neuron, allowing ___________ of neural pathways.

1. Brain 2. Decussation Note: Because of the crossing-over of fibers (decussation), the right cerebral hemisphere controls the musculature on the left side of the body, whereas the left hemisphere controls the right musculature.

Regarding Ascending Tracts Of White Matter... 1. Ascending fiber tracts convey sensory information from cutaneous receptors, proprioceptors, and visceral receptors to the __________. 2. Most of the sensory information that originates in the right side of the body crosses over to eventually reach the region on the left side of the brain that analyzes this information. Similarly, the information arising in the left side of the body is ultimately analyzed by the right side of the brain. This switching sides of where information is received and processed is called _______________ and occurs in the medulla oblongata.

1. Pyramidal tracts 2. Extrapyramidal tracts

Regarding Descending Tracts Of White Matter... 1. Descending fiber tracts that originate in the brain consist of two major groups: what are they?

Glutamic acid and Aspartic Acid. - Glutamic acid (or glutamate) is the major excitatory neurotransmitter in the brain, producing excitatory postsynaptic potentials (EPSPs) in at least 80% of the synapses in the cerebral cortex. - Astrocytes take glutamate from the synaptic cleft, as previously described, and couple this to increased glucose uptake and increased blood flow via vasodilation to the more active brain regions.

Regarding Excitatory Neurotransmitters... What are the 2 amino acids that function as excitatory neurotransmitters in the CNS?

1. Ascending Tracts 2. Descending Tracts

Regarding Spinal Cord Tracts... 1. Sensory information from most of the body is relayed to the brain by means of ____________ _______ of fibers that conduct impulses up the spinal cord. 2. When the brain directs motor activities, these directions are in the form of nerve impulses that travel down the spinal cord in ____________ ________ of fibers.

Basal nuclei; Neurons in the basal nuclei are called higher motor neurons.

Regarding a function of the Cerebellum... - The Cerebellum receives input from proprioceptors (joint, tendon, and muscle receptors) and works together with the _______ ______ and motor areas of the cerebral cortex to coordinate body movements.

Arcuate Fasciculus

Regarding the Broca's & Wernicke's Areas... - It appears that the concept of words originates in Wernicke's area. Thus, in order to understand words that are read, information from the visual cortex (in the occipital lobe) must project to Wernicke's area. - Similarly, in order to understand spoken words, the auditory cortex (in the temporal lobe) must send information to Wernicke's area. - To speak intelligibly, the concept of words originating in Wernicke's area must be communicated to the motor speech (Broca's) area; this is accomplished by a fiber tract called the ________ ________.

Red Nucleus

Regarding the Midbrain... The ______ _______, an area of grey matter deep in the midbrain, maintains connections with the cerebrum and cerebellum and is involved in motor coordination.

Corpora Quadrigemina

Regarding the Midbrain... The _______ ___________ are four rounded elevations on the dorsal surface of the midbrain. The two upper mounds are involved in visual reflexes. The inferior mounds, immediately below serve as relay centers for auditory info.

Pituitary Gland

Regarding the physical make-up of the Pituitary Gland... - The pituitary gland is located immediately inferior to the hypothalamus. - Indeed, the posterior pituitary derives embryonically from a down-growth of the diencephalon, and the entire pituitary remains connected to the diencephalon by means of a stalk.

Synaptic Vesicles! - Neurotransmitter molecules within the presynaptic neuron endings are contained within many small, membrane-enclosed synaptic vesicles. - In order for the neurotransmitter within these vesicles to be released into the synaptic cleft, the vesicle membrane must fuse with the axon membrane in the process of exocytosis. - Exocytosis of synaptic vesicles, and the consequent release of neurotransmitter molecules into the synaptic cleft, is triggered by action potentials that stimulate the entry of Ca2+ into the terminal bouton through voltage-gated Ca2+.

Regarding the release of Neurotransmitters, they are released in what?

Astrocytes (CNS)

Regulatory molecules from _____________ (A CNS glial cell) stimulate the capillary endothelial cells to produce the proteins of the tight junctions, which are essential for the blood-brain barrier. Regulatory molecules from ____________ also stimulate the endothelial cells to produce carrier proteins, ion channels, and enzymes that destroy potentially toxic molecules. These are required for the rapid transport of nutrients into the CNS, and for the elimination of toxic compounds that might cross the blood-brain barrier.

Pyramids

Remember that the Medulla Oblongata provides communication between the spinal cord and the brain... It's important to realize that many of these fiber tracts cross to the contralateral side in elevated triangular structures in the medulla called the ________. Thus, the left side of the brain receives sensory information from the right side of the body and vice versa. Similarly, because of the decussation (crossing over) of fibers, the right side of the brain controls motor activity in the left side of the body and vice versa.

Myelencephalon = Medulla Oblongata

Remember that the hindbrain, also called the rhombencephalon, is composed of two regions... 1. Metencephalon 2. Myelencephalon What is the Myelencephalon composed of?

Hippocampus; - Stress can impair memory consolidation by the hippocampus.

Researchers have demonstrated that people with post-traumatic stress disorder (PTSD) often have atrophy of the _________________.

Basal Nuclei control voluntary actions!

The basal nuclei are masses of grey matter composed of neuron cell bodies located deep within the white matter of the cerebrum. The basal ganglia are actually subcortical nuclei (collections of neuron cell bodies in the CNS) that control what?

AChE (Acetylcholinesterase); Note: AChE hydrolyzes acetylcholine into acetate and choline.

The bond between ACh and its receptor protein exists for only a brief instant. The ACh-receptor complex quickly dissociates but can be quickly re-formed as long as free ACh is in the vicinity. In order for activity in the postsynaptic cell to be stopped, free ACh must be inactivated very soon after it is released. The inactivation of ACh is achieved by means of an enzyme called?

Peripheral Nervous System (PNS)

The central nervous system communicates with the body by means of nerves that exit the CNS from the brain (cranial nerves) and spinal cord (spinal nerves). These nerves, together with aggregations of cell bodies located outside the CNS, constitute the __________ ______ _______.

Convolutions

The cerebral cortex is characterized by numerous folds and grooves called _____________.

Memory Consolidation

The conversion of a short-term memory into a more stable long-term memory is called?

1. Spino- 2. Spinal

The fiber tracts within the white matter of the spinal cord are named to indicate whether they are ascending (sensory) or descending (motor) tracts. 1. The names of the ascending tracts usually start with the prefix __________ and end with the name of the brain region where the spinal cord fibers first synapse. 2. The names of descending motor tracts, conversely, begin with a prefix denoting the brain region that gives rise to the fibers and end with the suffix _________.

Reflex Arc

The functions of the sensory and motor components of a spinal nerve can be understood most easily by examining a simple reflex; that is, an unconscious motor response to a sensory stimulus. This included figure demonstrates the neural pathway involved in a reflex arc. Stimulation of sensory receptors evokes action potentials that are conducted into the spinal cord by sensory neurons. In the example shown, a sensory neuron synapses with an interneuron, which, in turn, synapses with a somatic motor neuron.

Depolarization

What does this describe? "The potential difference between the two recording electrodes is reduced. Na+ ions rush into the cell."

Hindbrain

The hindbrain, also called the rhombencephalon, is composed of two regions... 1. Metencephalon (Pons & Cerebellum) 2. Myelencephalon (Medulla Oblongata)

Myelencephalon

The medulla oblongata is also called what?

1. Neurons - Neurons are the basic structural and functional units of the nervous system. They are specialized to respond to physical and chemical stimuli, conduct electrochemical impulses, and release chemical regulators. 2. Supporting cells (Neuroglia) - Supporting cells aid the functions of neurons and are about five times more abundant than neurons. In common usage, supporting cells are collectively called neuroglia. Unlike neurons, which do not divide mitotically, neuroglia are able to divide by mitosis.

The nervous system is composed of only two principal types of cells; what are they?

1. The central nervous system (CNS), which includes the brain and spinal cord. 2. The peripheral nervous system (PNS), which includes the cranial nerves arising from the brain and the spinal nerves arising from the spinal cord.

The nervous system is divided into two categories. What are they?

Voltage-gated Channels

The opening of these type of channels is stimulated by depolarization. These ion channels, so called _______ ______ _______ are channel gates that are closed at the resting membrane potential of −70 mV and open in response to depolarization of the membrane to a threshold value.

Hypothalamus; Limbic System

The parts of the brain that appear to be of paramount importance in the neural basis of emotional states are the ____________ and the ___________ ________.

Visiospacial Tasks

The right hemisphere is specialized for?

1. Increased diameter of the axon, because this reduces the resistance to the spread of charges by cable properties. 2. Myelination, because the myelin sheath results in saltatory conduction of action potentials. Note: The action potential produced at the last region of the axon has the same amplitude as the action potential produced at the first region. Action potentials are thus said to be conducted without decrement (without decreasing in amplitude).

The speed of action potential conduction is increased by?

Prefrontal Cortex

This part of the brain seems to confer the ability to consciously experience pleasure and reward. It receives input from all of the sensory modalities—taste, smell, vision, sound, touch, and others—and has connections with many regions of the limbic system.

True! - All cells in the body do have a resting membrane potential, where the inside of the cells are more negatively charged compared to the outside.

True Or False: All of the cells in the body maintain a potential difference (voltage) across the membrane, or resting membrane potential (rmp), in which the inside of the cell is negatively charged in comparison to the outside of the cell.

TRUE!

True or False? "Short-term memory is formed while a person is awake, the consolidation of short-term into long-term memory is promoted by sleep"

TRUE! Many important nuclei are contained within the medulla. Several nuclei are involved in motor control, giving rise to axons within cranial nerves 8-12.

True or false? "Many important nuclei are contained within the medulla."

True!

True or false? "The conduction of an action potential in both a myelinated and unmyelinated axon occurs without decrement."

Monoamines are regulatory molecules derived from amino acids. Dopamine, norepinephrine (noradrenalin), and epinephrine (adrenalin) are placed in a subfamily of monoamines called catecholamines. Monoamine neurotransmitters do not directly cause opening of ion channels in the postsynaptic membrane. Instead, these neurotransmitters act by means of an intermediate regulator, known as a second messenger. In the case of some synapses that use catecholamines for synaptic transmission, this second messenger is cAMP.

Understand how the different monoamines work as neurotransmitters.

1. Oxytocin stimulates contractions of the uterus during labor. 2. ADH stimulates the kidneys to reabsorb water and thus to excrete a smaller volume of urine. Note: Neurons in the hypothalamus also produce hormones known as releasing hormones and inhibiting hormones that are transported by the blood to the (anterior pituitary). These hypothalamic releasing and inhibiting hormones regulate the ability of the anterior pituitary to produce and secrete its hormones.

What are the 2 hormones that the Pituitary Gland secretes?

1. Thalamus 2. Hypothalamus 3. Epithalamus 4. Pituitary Gland

What are the 4 components of the Diencephalon?

1. Nicotinic ACh receptors: So named because they can also be activated by nicotine. 1. Muscarinic ACh receptors: So named because these effects can also be produced by muscarine.

What are the two types of cholinergic receptors (receptors for ACh)?

Membrane potentials are largely the result of the permeability properties of the plasma membrane. - The membrane traps large, negatively charged organic molecules within the cell and permits only limited diffusion of positively charged inorganic ions. - These properties result in an unequal distribution of these ions across the membrane. - The action of the Na+/K+ pumps also helps to maintain a potential difference.

What causes resting membrane potentials to exist?

Pituitary Gland Note: Chronic stimulation of the lateral hypothalamus, for example, can make an animal eat and become obese, whereas stimulation of the medial hypothalamus inhibits eating. Other areas stimulate thirst and the release of antidiuretic hormone (ADH) from the posterior pituitary.

What does this describe the function of? "Contains neural centers for hunger and thirst; important in the regulation of body temperature; and hormone secretion."

Pineal Gland

What does this describe the function of? "Secretes melatonin that helps regulate circadian (daily) rhythms."

Repolarization

What does this describe? "A return to the resting membrane potential is known as?"

Hyperpolarization

What does this describe? "If stimulation causes the inside of the cell to become more negative than the resting membrane potential, the line on the oscilloscope will deflect downward. This can be caused either by positive charges leaving the cell or by negative charges entering the cell."

In order for activity in the postsynaptic cell to be stopped, free ACh must be inactivated very soon after it is released. Thus, if AChE isn't working, then the activity in the postsynaptic wouldn't ever stop.

What happens if the enzyme AChE (Acetylcholinesterase) isn't working?

Multiple sclerosis (MS) is produced by an autoimmune attack by T lymphocytes, causing lymphocytes and monocyte-derived macrophages to enter the brain and target the myelin sheaths. The inflammation this produces causes demyelination, partial restoration of the destroyed myelin with neuroglia scarring, and axon degeneration. It is a chronic remitting and relapsing disease with highly variable symptoms, including sensory impairments, motor dysfunction and spasticity, bladder and intestinal problems, fatigue, and others. Treatment for MS includes drugs that reduce autoimmune activity and inflammation, and drugs that interfere with the entry of auto-reactive T cells into the CNS. These drugs help in treating the symptoms of MS, but do not restore myelin sheaths or cure the disease.

What is Multiple Sclerosis (MS) caused from?

Unlike other organs, the brain cannot obtain molecules from the blood plasma by a nonspecific filtering process. Instead, molecules within brain capillaries must be moved through the endothelial cells by diffusion and active transport, as well as by endocytosis and exocytosis. This feature of brain capillaries imposes a very selective blood-brain barrier.

What is the function of the blood-brain barrier and what is the anatomy

The mesencephalon, or midbrain, is located between the diencephalon and the pons.

What is the location of the Midbrain (Also called the mesencephalon)?

-70 mV

What is the resting membrane potential for a membrane?

long-term potentiation (LTP). - Long-term potentiation may favor transmission along frequently used neural pathways and thus may represent a mechanism of neural "learning." - During LTP, the insertion of AMPA receptors for glutamate into the postsynaptic membrane is increased.

When a presynaptic neuron is experimentally stimulated at a high frequency, even for just a few seconds, the excitability of the synapse is enhanced when this neuron pathway is subsequently stimulated. The improved efficacy of synaptic transmission may last for hours or even weeks and is called ______ _______ ________.

Recruitment

When an entire collection of axons (in a nerve) is stimulated, different axons will be stimulated at different stimulus intensities. A weak stimulus will activate only those few axons with low thresholds, whereas stronger stimuli can activate axons with higher thresholds. As the intensity of stimulation increases, more and more axons will become activated. This process, called __________, represents another mechanism by which the nervous system can code for stimulus strength.

- People first enter non-REM sleep of four different stages, and then ascend back through these stages to REM sleep. - After REM sleep, they again descend through the stages of non-REM sleep and back up to REM sleep. - Each of these cycles lasts approximately 90 minutes, and a person may typically go through about five REM-to-non-REM cycles a night. - A great amount of time is spent in slow-wave sleep during the first half of a night's sleep; this gives way to mostly REM sleep during the second half of the sleep.

When people first fall asleep, they enter what kind of sleep? (REM or Non-REM)

1. Epithalamus 2. Hypothalamus

Where is each of the following located? 1. Pineal Gland 2. Pituitary Gland

Insula Lobe

Which lobe does this describe? - Functions in the encoding of memory and in the integration of sensory information. - It receives olfactory, gustatory (taste), auditory, and somatosensory (principally pain) information, and helps control autonomic responses to the viscera and cardiovascular system.

Hypothalamus

Which part of the Diencephalon does this describe? - The is the most inferior portion of the diencephalon; it forms the floor and part of the lateral walls of the third ventricle. - This small but extremely important brain region contains neural centers for hunger and thirst; the regulation of body temperature; and hormone secretion from the pituitary gland.

Thalamus

Which part of the Diencephalon does this describe? - This composes about four-fifths of the diencephalon and forms most of the walls of the third ventricle. - It acts primarily as a relay center through which all sensory information (except smell) passes on the way to the cerebrum.

Epithalmus

Which part of the Diencephalon does this describe? - This is the dorsal segment of the diencephalon, containing the choroid plexus over the third ventricle where cerebrospinal fluid is formed. - This part of the diencephalon also contains the pineal gland, which secretes the hormone melatonin that helps regulate circadian (daily) rhythms.

Suprachiasmatic Nuclei

Within the anterior hypothalamus are _____________ ________ (SCN). These nuclei contain about 20,000 neurons that function as "clock cells," with electrical activity that oscillates automatically in a pattern that repeats about every twenty-four hours. The SCN functions as the master regulator of the body's circadian rhythms (from the Latin circa = about; diem = day). These are the physiological processes—including metabolism, sleep, body temperature, blood pressure, hormone secretion, and many others—that repeat at approximately 24-hour intervals. For these to function properly, the neuron clocks of the SCN must be entrained (synchronized) to the day/night cycles.

Neuronal Recruitment; Note: The higher the recruitment the stronger the muscle contraction will be.

__________ _________ occurs when more axons within a nerve become active as a result of a stronger stimulus.