A&P 2
Where must threshold be reached to send a signal all the way down the length of the neuron?
At the trigger zone AND at each node of ranvier Signal conduction down an axon requires the action potential to be generated (or regenerated) at each exposed portion of the axon. To generate an AP at each section of the neuron, you must bring that section to threshold so that voltage gated sodium and potassium channels can open. Typically, the first place where an AP is generated is at the trigger zone (initial segment). Then, the AP must be recreated at each section of the neuron to transmit the signal to the end of the neuron.
Which of the following influences your decision making processes LEAST?
Basal ganglia
Using Figure 1, what is found in "F"? dorsal rami
Both sensory and motor neurons axons
Where are the cell bodies of the motor neurons in cranial nerves III (3) and V (5)?
Brainstem nuclei
For you to be fully consciously aware of sensory stimuli in the environment, the ____________ must receive neural signals.
Cerebral cortex Correct! To accurately perceive stimuli (be consciously aware of stimuli), the sensory information must reach the cerebral cortex. To consciously control skeletal muscle, the motor signal must originate in the primary motor cortex (precentral gyrus) of the cerebral cortex. All other regions of the brain/spinal cord may be involved in signal transmission or motor initiation, but if the signal does not have some component that reaches the cerebral cortex, you have no precise knowledge of the activity and are not able to localize it with specificity.
In the condition Bell's palsy, muscles that allow you to smile, blink and grimace cannot contract. What would cause this?
Defect of facial nerve Correct! The facial nerves provide somatic motor output to the face (innervate muscles of facial expression). If they become inflamed due to infection, they cannot function properly and send signals to the skeletal muscles, and therefore the skeletal muscles cannot contract. This causes paralysis of the facial muscles. The trigeminal nerves provide sensory innervation to the skin of the face. The vagus nerves provide parasympathetic control to the visceral of the thoracic and abdominal cavity. The cervical spinal nerves may make up the accessory cranial nerve or they may contribute to the cervical plexus. Neither serve the muscles of the face.
Broca's area is a primary area.
False Both Broca's and Wernicke's areas are association areas. Individuals with damage in Broca's area typically have trouble with the production of language because this area makes the motor plan for speech production and allows us to create grammatical structure in our speech. Broca's is a part of the premotor cortex. Individuals with Wernicke's aphasia are typically unable to understand verbal, written or signed language because Wernicke's is a multimodal association area that brings together visual and auditory information to comprehend language.
True or False? Sperm in the testes are fully motile.
False Right! Semen from accessory glands in the male reproductive system provides nutrients to sperm so that they may swim. Sperm in the testes and epididymis are not fully capable of swimming.
Using the Spinal Cord Figure, what would you expect to find in #12?
Multipolar neuron axons
Using the Spinal Cord Figure, what would you expect to find in #12? ventral root
Multipolar neuron axons
Where does a neurotransmitter usually bind to chemically gated channels on postsynaptic multipolar neurons?
On the dendrites and cell body
In the morning, your alarm clock stimulates your ____ to wake you up.
RAS
Which of the following does NOT cause the release of a hormone from an endocrine organ?
Somatic motor neuron stimulation Correcto! Hormones are released due to the actions of arriving hormones, circulating levels of blood ions/chemical (sodium, potassium, calcium or glucose) or due to neural stimuli. However, those neural stimuli do not come from somatic motor neurons because somatic motor neurons innervate skeletal muscle. Only visceral motor neurons directly stimulate glands (composed of epithelial tissue) or if the endocrine organ is a neural structure (like the hypothalamus), then an interneuron can stimulate the hormone's production and release.
Where do preganglionic neurons synapse with postganglionic neurons in the sympathetic nervous system?
Sympathetic ganglia Correct! Preganglionic neurons synapse with postganglionic neurons in autonomic ganglia. Ganglion is a generic term referring to a collection of cell bodies in the PNS. Autonomic ganglia contain the cell bodies of postganglionic neurons. Both the sympathetic and parasympathetic branches have their own ganglia. In sympathetic ganglia, only sympathetic preganglionic neurons synapse with sympathetic postganglionic neurons. In parasympathetic ganglia, only parasympathetic preganglionic neurons synapse with parasympathetic postganglionic neurons.
What is the importance of the skeletal muscles in the spermatic cord and scrotum?
Temperature regulation of the testes
Which of the following is an ipsilateral polysynaptic spinal somatic reflex that regulates muscle tension protectively?
Tendon reflex Correct! Spinal reflexes feature the spinal cord as the integration (processing) center of the reflex arc. Cranial reflexes use the brainstem as the processing center. Somatic refers to skeletal muscle and not visceral (gut, heart) muscle. Reflexes can be learned (like riding a bike) or innate (crossed extensor, stretch etc). Ipsilateral means that the neural connections are all occurring on the same side of the body, contralateral means they involve neurons on both sides of the body. Polysynaptic reflexes involve more than just the sensory and motor neurons (they also involve interneurons) and feature more than one synapse in the reflex arc. The tendon reflex involves an interneuron in the spinal cord, neurons all on the same side of the body and skeletal muscles.
Which is NOT true of the conscious somatic sensory pathways?
They both synapse in the spinal cord
Using the Spinal Cord Figure, assume these are spinal cord sections C6, C7, and C8. Which accurately describes 11 spinal nerve?
They braid together in the brachial plexus
True or False? The corpus lutuem is formed from the unovluated cells of a mature follicle after the egg has left the ovary.
True Yes! Each month, a primordial follicle develops into a mature follicle. The egg within the follicle will be ovulated (under the influence of LH) and the majority of the follicle cells will remain in the cortex of the ovary. These cells (under the influence of LH) will form the corpus luteum. The corpus luteum produces progesterone and estrogen that affect the uterus endometrium.
In terms of generating a depolarizing or hyperpolarizing graded potential on a postsynaptic cell, what do you think will be the most important factor?
Type of ion channel opened
Produces hormones in response to both acute and chronic stress
adrenal
Match the term from the list with the description below. Each term may be used only once. Produces hormones in response to both acute and chronic stress Delivers regulatory hormones to the anterior pituitary Releases hormones in response to blood glucose levels Requires iodine for proper function Releases hormone that promotes milk ejection in nursing females
adrenal glands, hypophyseal portal system, pancreas, thyroid, posterior pituitary
Stimulated by releasing and inhibiting hormones
ant p
Which of the following allows communication between the neurons of the two cerebral hemispheres?
corpus callosum Right! The quantity of anatomy has suddenly increased, causing mass depolarization of your neurons. Flashcards are helpful, drawings, the fun with figures, and free websites like getbodysmart.com (see the link on our external links). Always associate function with the structures you are studying. The corpus callosum is a large band of white matter that runs between the cerebral hemispheres. Axons make up white matter and axons carry signals. The meninges are connective tissue sheets (dura mater, arachnoid mater and pia mater) that protect the brain. Cranial nerves extend into the peripheral nervous system and serve many special sensory and motor functions. Projection fibers carry information to the cortex from subcortical regions.
Delivers regulatory hormones to the anterior pituitary
hypophyseal portal system
Auditory memories are stored in:
the temporal lobe of the cerebral cortex.
In the male, urine and gametes share a pathway out of the body.
true
Using the Eye Figure above, which structure is responsible for the majority of light refraction?
1 cornea
The figure below highlights glands/organs that participate in the Endocrine system through their production and release of hormones. I expect you to have a basic familiarity with the location and names of these structures for our next class session where will be discussing the endocrine system
1. pineal 2. hypothal 3. pit 4. thyroid 5. parathy 6. thymus 7. adrenal 8. pancreas 9. ovary 10. testes
At minumum, how many neurons extend from the CNS to visceral targets served by the autonomic nervous system (how many in series, not how many to all the targets in the whole body)?
2 Correct! 2 motor neurons extend from the CNS to visceral targets served by the autonomic nervous system. The preganglionic neuron has its cell body in the CNS, its axon extends to the periphery. Out in the periphery it will not synapse with a target cell, but instead with a postganglionic neuron cell body. This synapse will occur in an autonomic ganglion. From the ganglion, the postganglionic axon will extend to the target.
Arrange the following in the correct order to generate an EPSP between 2 cells: 1. Neurotransmitter binds to receptors 2. Presynaptic cell reaches threshold 3. Voltage gated calcium channel opens at terminal end 4. Chemically gated sodium channels opens on postsynaptic cell 5. Synaptic vesicles fuse to presynaptic membrane
2, 3, 5, 1, 4
Using the Spinal Cord Figure, where is the first synapse in the crossed extensor reflex?
4 posterior gray horn
Using the Eye Figure above, what structure is used to adjust the shape of the lens?
5 ciliary body
To create a graded depolarization in the postsynaptic cell, the following events would need to occur in which of the following orders (you may or may not need to use all numbers below). 1. Voltage gated calcium channels open. 2. Neurotransmitter binds to chemically gated channels. 3. Synaptic vesicles migrate to cell membrane. 4. Neurotransmitter released into synaptic cleft. 5. Action potential arrives at terminal end (knob). 6. Sodium rushes into the postsynaptic cell. 7. Potassium rushes out of the postsynaptic cell.
5, 1, 3, 4, 2, 6
Using the Spinal Cord Figure, neurons found in #____ transmit position, vibration and fine touch.
6 posterior column
What directly causes a voltage gated channel to open?
A change in the transmembrane potential due to some factor
What directly causes a voltage gated channel to open?
A change in the transmembrane potential due to some factor Correct! Voltage gated channels are membrane proteins that open when the surrounding membrane transmembrane potential (electricity) changes. Not just any change in the membrane potential will cause the voltage gated channel to open, but only when the membrane reaches a particular transmembrane potential. This membrane potential value that causes the voltage gated channel to open is called threshold. Chemically gated channels open when a chemical binds to a receptor on the channel. Mechanically gated channels open when the surrounding membrane (or channel) is physically changed (deformed). ATP can act as a neurotransmitter causing certain chemically gated channels to open.
What is most likely to stimulate an action potential in a resting neuron?
A depolarizing graded potential near the trigger zone
People diagnosed with depression often have low extracellular levels of the neurotransmitter serotonin. Which of the following would increase extracellular serotonin levels?
A medication that interferes with the activity of serotonin degrading enzymes
Which neuron will transmit a signal down the axon the fastest?
A neuron with a myelinated, wide diameter axon
What directly causes a chemically gated channel to open?
A neurotransmitter binding on the chemically gated channel
Which of the following will cause a graded hyperpolarization on a postsynaptic neuron?
A neurotransmitter binding to a chemically gated potassium channel
Which of the following will cause a graded hyperpolarization on a postsynaptic neuron?
A neurotransmitter binding to a chemically gated potassium channel Correct! At a synapse, the presynaptic cell communicates with the postsynaptic cell. At a chemical synapse, the presynaptic cell releases a chemical (neurotransmitter) that binds to chemically gated channels on the membrane of the postsynaptic cell. When a chemically gated channel opens, specific ions may move down their concentration gradients (from high to low). The concentration gradient for potassium is to move out of the cell. When potassium moves out of the cell, it removes positive ions from the cellular interior, thus leaving the cell more negative. A hyperpolarization is a change in the transmembrane potential from resting values to something more negative (perhaps -70 mV to -90 mV). Neurotransmitters do not bind to voltage gated channels. Opening a sodium channel would lead to a graded depolarization. Because sodium would move down its concentration gradient into the cell, this would make the interior less negative (move closer to 0 or positive values; perhaps from -70mV to -20 mV).
Using the Graph, the transmembrane potential observed during time "U" is most like the result of ____.
A sodium channel close to the trigger zone opening for a long time
How can pregnancy be prevented in humans?
ALL THE ABOVE -Using hormonal methods to prevent ovulation in the female -Placing a barrier between the sperm and egg (such as a condom or diaphragm) -Placing a foreign body in the uterus to disturb the uterine environment -Providing drugs to the male to prevent sperm formation -Cutting the passageways for gamete transfer in either the male or female -Timing sexual encounters to prevent contact between ovulated eggs and received sperm -Preventing insemination by abstaining from sex -All of the above Correct! All of the above are either methods that prevent formation of gametes (hormonal drugs in men or women), prevent meeting of gametes (abstinence, timing, barriers, cutting of pathways) or should gametes meet, preventing the appropriate uterine environment (intrauterine devices). Please do not mistake this question as a position against unintended pregnancies; it is more a means to highlight the processes involved in successful gamete production, transport, fertilization and pregnancy establishment. Each of these methods is also relevant to creating intended pregnancies.
Which is NOT located between the two cerebral hemispheres?
Association fibers
If ____________ are non-functional, the interstitial fluid environment of the brain cannot be regulated. (interstitial fluid is the extracellular fluid around tissue cells, here it is the fluid around brain cells).
Astrocytes Correct! Astrocytes are neuroglia that regulate the interstitial fluid environment of the brain by working with blood vessels to form the blood brain barrier. Blood capillaries are typically very leaky and allow substances to easily pass from the blood to the fluid surrounding tissues (interstitial fluid). But in the brain, the astrocytes make the blood capillaries less leaky and force most substances to move between the blood and brain tissue via tightly regulated cell membrane channels/carriers. Additionally, astrocytes mop up excess ions and neurotransmitter surrounding neurons. Without properly functioning astrocytes, the interstitial environment of the brain cannot be maintained. Schwann cells and satellite cells are cells of the PNS and therefore their function does not influence the brain interstitial environment. Oligodendrocytes are responsible for myelinating axons in the CNS which allows the neurons to send signals faster.
Why is it hard to remove or undo an implicit bias?
Because an implicit bias is a network of facilitated neurons
Why are warm, flavorful meals strongly linked with pleasant memories
Because smell pathways directly synapse with the amygdala
Why are warm, flavorful meals strongly linked with pleasant memories?
Because smell pathways directly synapse with the amygdala
Why are there two enlargements in the spinal cord?
Because these regions of the spinal cord have more neurons to serve more targets. Correct! The spinal cord is enlarged in the cervical and lumbar (lumbosacral) regions. There are more neurons found in these regions relative to some other parts of the spinal cord because these regions serve the limbs. The cervical region is the site of cell bodies of motor neurons to the muscles of the upper limb as well as the site where sensory neurons relay information from the upper limbs. The lumbar (lumbosacral) region provides the same role for the lower limb. In the thorax there are fewer skeletal muscles and thus fewer motor neurons leaving the spinal cord. While there are many visceral targets in the thorax and abdomen, these targets are often served by neurons originating in the brain (parasympathetic neurons) or in higher or lower levels of the spinal cord. We will address these targets later in the term. The thickness of the meninges does not really change through the spinal canal.
Using the Spinal Cord Figure, where is the best place for a physician to collect a sample of CSF for examination?
Between 13 & 14, but not at this spinal cord level
What will happen to body temperature if TSH cannot be made?
Body temperature will decrease Right! Body temperature is related to body metabolic rate. The higher the metabolic rate, the higher the body temperature. We are endothermic (warm blooded) animals because of our resting high metabolic rates - through our high constant production and usage of ATP, we maintain an elevated, mostly constant body temperature. Our elevated metabolic rate is due to the constant stimulation of body cells by thyroid hormone (see here for those intersted: http://www.ncbi.nlm.nih.gov/pubmed/18279015Links to an external site.). TH release from the thyroid gland is due to stimulation by the anterior pituitary gland hormone TSH (thyroid stimulating hormone). TSH is released from the anterior pituitary under the action of the hypothalamic hormone TRH (thyrotropin releasing hormone). TRH is released from the hypothalamus into the blood of the hypophyseal portal system. It travels a very short distance to the anterior pituitary where it gets out of the blood and stimulates certain cells of the anterior pituitary to release TSH. When TSH is released, it gets into the blood of the hypophyseal portal system and travels to the rest of the body. TSH binds to receptors on the surface of thyroid gland cells and causes TH production and release. Once in the blood, TH binds to receptors within every single body cell and increases cellular metabolic rate. So, without TRH, there can be no TSH release and then no TH release and then no high, sustained metabolic rate and no high body temperature.
Which of these is NOT involved in rolling your eyes?
CN II these are CN IV CN VI CN III
Using Figure 1, what is located in "R"?
Cell bodies of spinal nerve sensory neurons
Using Figure 1, what is located in "R"? dorsal root ganglion
Cell bodies of spinal nerve sensory neurons
You are sitting in class when all of a sudden a desk falls over. You instantly pick up your head, turn towards the sound and focus your eyes on the location from which it came. Which of the following cranial nerves are involved in this scenario?
Cranial nerves (CNs) VIII, III, IV, VI & XI Right! The sound of a falling desk chair is detected by CN VIII (vestibulocochlear); the auditory information enters the brainstem and synapses in relay centers in the brainstem (inferior colliculi of the midbrain, for those interested). From the brainstem, information is relayed to the motor neurons on CN III, IV & VI (oculomotor, trochlear & abducens) to turn your eyes in the proper direction and adjust the lens/pupil in the correct manner. Information is also relayed to CN XI (spinal accessory nerve) to activate the trapezius and sternocleidomastoid muscles to turn the head towards the sound. This is a cranial nerve reflex and is an innate reflex - meaning, a prebuilt series of neurons that make a pathway. The pathway does not require the higher brain centers to process information or send signals in any way. This reaction to the stimulus will occur without your thinking about it. The other cranial nerves have specific functions that are important in many ways, but their function is not part of the described reaction.
Spinal nerves C5-T1 form the brachial plexus. Suppose you damage the ventral root of your C6 spinal nerve on the right side. What would be the result?
Decreased muscle force production of the right upper limb Right! The brachial plexus contains neurons that innervate the upper limb. In a brachial plexus, multiple spinal nerves mix and mingle so that axons from each spinal nerve find their way into many different nerves. These "new" nerves then serve structures in the upper limb (either muscles or regions of skin). In this question, the ventral root of C6 is damaged. The ventral root contains motor neurons that innervate skeletal muscle. If these motor neurons are damaged, the muscle cells served by the axons emerging from C6 will not be able to contract and contribute to force production. However, because each whole muscle is served by many axons from many different spinal nerves, the whole muscle (and limb) will still have neural activation and be able to produce some force, although less muscle cells can be activated and thus less overall force production. There will not be loss of sensation because the ventral root is damaged which only contains motor neurons. The sensory neurons travel in the dorsal root and are still able to conduct sensory information. Breathing is a combined function of the diaphragm and rib movement. The diaphragm is innervated by the phrenic nerve from the cervical plexus. The ribs are served by nerves from thoracic spinal nerves. C6 does not contribute to the phrenic nerve. Even if it did, the phrenic nerve has axons from multiple spinal nerves and will still be able to function should one spinal root be damaged.
Which of the following most accurately describes what is happening in a resting neuron?
During rest, the membrane is more permeable to potassium than it is to sodium. Correct! While a resting cell is neither sending nor receiving a signal, ions are still crossing the membrane. Sodium and potassium ions are actively pumped across the membrane through the Sodium/Potassium pumps. Both sodium and potassium are also moving passively across the membrane using leak channels, however, there are 100X more potassium leak channels than sodium leak channels. Hence, the resting membrane is more permeable to potassium than it is to sodium.
How does subconscious information reach lower motor neurons (what are the downward pathways that carry this information)?
Extrapyramidal pathways Correct! Somatic motor control features at minimum an upper motor neuron and a lower motor neuron. The upper motor neuron cell body is in the upper CNS, the axon extends down to the lower motor neuron. The lower motor neuron cell body is in the anterior gray horn (if a spinal nerve). The basal ganglia and cerebellum unconsciously control skeletal muscles in two ways: (1) by communicating with the cerebral cortex and (2) by communicating with brainstem nuclei. From the brainstem nuclei, axons project down through the spinal cord white matter to synapse on the lower motor neuron - it is these axons that make up the extrapyramidal system (also called indirect pathways). The direct pathway is also called the pyramidal system or corticospinal pathway; the upper motor neuron is in the cerebral cortex and the axons project down through the brainstem and spinal cord to the lower motor neuron. When the axons of this system pass through the cerebrum, they are called the internal capsule. When they pass through the midbrain, they are called the cerebral peduncles. When they pass through the medulla oblongata, they are called the pyramids. When they pass through the spinal cord, they are called the anterior or lateral corticospinal pathways.
In the female, hormones from the anterior pituitary regulate the events in the ovary that cause maturation of a follicle and ovulation (ovarian cycle). What hormones are these?
FSH & LH Yes! The ovarian cycle describes the events that occur in the ovary each month. Under the influence of anterior pituitary hormones (FSH & LH), the follicle and egg develop (the follicular phase of the ovarian cycle - the first 14 days). Ovulation marks the end of the follicular phase. After ovulation, the follicle cells remain in the ovary and are stimulated by LH to become the corpus luteum. For the next 10-12 days, the corpus luteum secretes estrogen and progesterone (this is the luteal phase of the ovarian cycle and includes the time when the corpus luteum degenerates - total luteal phase is 14 days). During the luteal phase, the corpus luteum is stimulated by LH. Together the anterior pituitary hormones affect the activities of the ovary because the cells of the ovary have receptors for FSH & LH. The uterine cycle is caused by hormones from the ovary. Estrogen and progesterone are produced by cells of the follicles or the corpus luteum, structures that are and remain in the ovary. The uterus has receptors for estrogen and progesterone and is therefore affected by these hormones. GnRH (gonadotropin releasing hormone) is the hypothalamic hormone that causes FSH & LH release. Inhibin is a hormone produced by the ovaries or testes that inhibits GnRH and FSH, LH release. TRH & TSH are hormones from the hypothalamus and anterior pituitary, respectively, that are involved in thyroid hormone production and release.
In the ovary:
FSH and LH have an effect because ovarian cells have FSH/LH receptors.
Cutting both vas (ductus) deferens in the male creates sterility and greatly reduces semen volume.
False
Rods provide information about the wavelength of light.
False
Though theoretically possible, in the body neurons rarely generate IPSPs.
False
True or False? Motor and sensory information are carried on the same neuron.
False Correct! Sensory and motor information are carried on two different nerve cells (neurons). Neurons only carry information in one direction. Motor information must go away from the central nervous system, sensory information must come into the central nervous system.
True or False? The two cerebral hemispheres serve the exact same functions, just for opposite sides of the body.
False Correct! The two cerebral hemispheres may look similar, and they can have similar functions in certain regions, but other regions serve very different functions. Specifically, the areas associated with understanding, using and speaking language (Wernicke's and Broca's) are located only in the left hemisphere of almost all people. The region in the right hemisphere serves a different purpose (appreciation of tone of words). This division of cerebral labor is called hemispheric lateralization.
Color vision is best when the image strikes the optic disc.
False Right. The optic disc is the origin of the optic nerve and there are no photoreceptors at this blind spot. Color vision is best at the fovea centralis or focal point where there is a particularly high density of cones for color vision and the bipolar and ganglion cells are pushed aside and there are not blood vessels at this location, allowing for maximum visual acuity.
Body metabolic rate is lowest during REM sleep.
False Correct! During REM sleep, brain metabolic rate (measured by O2 consumption) increases above normal daytime levels. BP, HR and Respiratory rate also increase to normal day time levels. All of these are depressed about 30% during deep or NREM sleep.
The gustatory pathway has a direct synapse with the amygdala. t/f
False Right! It's the olfactory pathway that synapses with the amygdala.
Parasympathetic neurons synapse in the chain ganglia.
False sympathetic neurons synapse in the chain ganglia
Neither olfactory nor gustatory information stimulates the RAS. t/f
False. Although olfactory information does not stimulate the RAS and has no synapse in the thalamus, gustatory information does stimulates the RAS and can stimulate arousal.
_________ hormones travel in the blood _________ and bind to intracellular receptors.
Fat soluble; bound to carriers (mostly) Well done! Fat soluble hormones (adrenal cortex hormones, sex hormones and thryoid hormone) must travel in the blood bound to transport proteins (carriers). The blood is mostly water and being attached to carriers allows the hormones to dissolve in the blood. The carriers are not easily removed from the blood by the kidney or liver and fat soluble hormones are slowly released from the carriers so that they may affect their target cells. Therefore, one advantage of protein carriers is that they provide a reserve of hormones in the blood. Once these hormones reach their targets, they dissolve through the cell membrane (made mostly of fats) and find their receptors inside the target cell. Water soluble hormones are the opposite - they travel freely in the blood, but must bind to target cell receptors on the surface of the cell membrane.
After a difficult A&P exam, you relax in the hot tub while enjoying your favorite beverage. At first, the water feels uncomfortably warm, but after a few minutes, you are not longer uncomfortable. What explains your change in perception?
Fewer signals are received by your postcentral gyrus
People who wear contact lenses have decreased sensitivity to sensory stimuli on the anterior surface of the eye (cornea). What explains this decreased sensitivity?
For a given stimulus, fewer action potentials are generated in the trigeminal nerve
What cells carry visual information to the brain?
Ganglion cells Correct! The axons of the ganglion cells make up the optic nerves. While the photoreceptors, bipolar cells and horizontal cells are components of the retina (neural layer in particular), it is the axons of ganglion cells that actually carry the signal to the brain.
Ganglia are collections of neuron cell bodies in the peripheral nervous system. What is the equivalent of ganglia in the central nervous system?
Gray matter Correct! Gray matter are collections of neuron cell bodies in the central nervous system. White matter are collections of axons (similar to nerves of the PNS). Nerves are bundles of axons in the peripheral nervous system. Meninges are connective tissues that protect the brain and spinal cord.
Mr. and Mrs. A have been married for 40 years. Recently, Mrs. A has noticed that Mr. A has been having a time remembering the new people he has been meeting. He remembers well the neighbors that have lived next door for the last 20 years, but he keeps asking about the new couple that moved in next door 3 months ago. Again and again his wife reminds him that he has met them several times, but he insists that he has not. What do you think is happening to Mr. A?
He has decreased function of his hippocampus
Which of the following are the most important components of a CHRONIC stress reaction?
Hypothalamus, anterior pituitary and adrenal cortex Perfect! The acute stress response is how the body reacts to a sudden stress. Stress includes any emotional or physical stimulus that evokes the stress response. The body responds to acute stresses using the sympathetic nervous system - including its components the hypothalamus and adrenal medullae. Longer term stresses - ones that last beyond a few minutes - evoke the responses of the adrenal cortex and the hypothalamus and anterior pituitary that regulate it. The hypothalamus and posterior pituitary make and release, respectively, other hormones (ADH & oxytocin), that are not components of acute stress responses. ADH may be released during chronic stresses to augment the effects of aldosterone.
Which of the following would most likely cause an increase in FSH/LH levels?
Increased GnRH Right! This is a bit of an alphabet soup here. But each of the listed hormones is a hypothalamic regulatory hormone - meaning, it is released by the hypothalamus to regulate the anterior pituitary. Each listed does this: CRH --> ACTH --> Cortisol, Aldosterone (from aderenal cortex) GnRH --> FSH/LH --> Estrogen, Progesterone, Testosterone (depending on sex, from gonads) TRH --> TSH --> TH (thyroid horomone from thyroid glands) GHRH --> GH (growth hormone from ant. pit.)
What would happen if the dural sinuses were not able to collect CSF from the arachanoid granulation (in the adult)?
Intracranial fluid pressure would increase.
Testosterone is a steroid hormone made from cholesterol - it is fat soluble. How does testosterone affect the brain?
It diffuses through the blood brain barrier and binds to intracellular receptors
Which of the following is important in determining your motivational drives, learning and emotions?
Limbic system Correct! The limbic system is a functional grouping in the brain that involves part of the cerebrum (parts of several lobes, including the temporal) and the diencephalon (hypothalamus and even parts of the thalamus). This region is often called the "emotional brain" and because it plays huge roles in your motivational drives, it also dictates your behavior. The reward and punishment centers of the brain are localized here as are the regions essential to learning/memory (hippocampus). This is why emotional state plays a role in memory formation (think of where you were when you heard about the twin towers in Manhattan; think about where you were when you learned a loved one died). Neural activity in this region affects the whole functioning of the body particularly through the involvement of the hypothalamus and its extensive regulatory functions. The occipital lobe is important in visual information processing. The brainstem for regulating vegetative functions. The precentral gyrus is the location of the primary motor cortex which controls skeletal muscle.
Spinal nerve plexuses primarily serve:
Limbs Correct! Spinal nerve plexuses are sites where neurons from spinal nerves (eg C5, C6, C7) diverge and find new paths in new nerves (eg musculocutaneous). The new nerves then go on to serve targets primarily in the limbs. The cervical plexus forms new nerves that serve shoulder girdle muscles and the diaphragm, but the brachial (serving upper limb) and lumbar and sacral plexuses (serving lower limb) serve limbs. The advantage of the plexus system is that it provides targets (eg biceps brachii) with neurons from multiple spinal nerves (C5-C7). Should a single spinal cord segment or spinal nerve become non-functional, the muscle would still have other neurons serving it and the muscle would not lose function.
Which statement best describes the organization of the spinal cord?
Motor information and sensory information are segregated into specific regions of both gray matter and white matter. Correct! The spinal cord contains a core of gray matter with an outer layer of white matter. In the spinal cord, sensory and motor information is carried in specific tracts and pathways that segregate the information. Also, you can map the regions of the spinal cord that are associated with specific regions of the body and types of sensory or motor signals carried (ie pain versus pressure, skeletal muscle versus gut muscle). Sensory information is carried towards the spinal cord from the periphery and travels in posterior or lateral pathways to the brain. Motor information is carried away from the brain in anterior or lateral pathways towards the spinal cord and then out to peripheral targets.
Using Figure 1, your patient reports that he cannot feel light touch, vibration or pressure with her left hand. After testing, you determine that he is able to sense pain and temperature correctly. Where might there be damaged neurons?
O posterior column, fine touch vibration pressure proprioception
Using Figure 1, where is the first synapse in the flexor withdrawal reflex?
P at the posterior gray horn
How does position information reach the conscious sensory centers of the brain?
Posterior column-medial lemniscus pathways Correct! The posterior-column medial lemniscus pathway goes from the spinal cord to the brain (ascending information), ultimately terminating in the postcentral gyrus of the parietal lobe of the cerebrum. This information is consciously perceived. The cerebellum is an unconscious motor processing center. One of its roles is to compare planned motor information from the premotor cortex with actual body position - to do this, it needs to know your actual body position. Some position information reaches the cerebellum from the eyes and the inner ear, but much of it comes from position receptors in the body's muscles/joints. Position information from below the head and neck reach the cerebellum by way of the spinocerebellar pathways. Spino if for spinal cord, cerebellar, well, I think you know. The spinothalamic pathway goes from the spinal cord to the thalamus (ascending information), ultimately terminating in the postcentral gyrus of the parietal lobe of the cerebrum. This information is consciously perceived.
the corticospinal tracts (pathway). These are a motor pathway carrying information from the brain down to excite skeletal muscles. Where are the cell bodies of the upper motor neurons (first neurons) in the chain for the corticospinal pathway?
Precentral gyrus Right. The corticospinal pathway is a descending pathway that carries motor information to skeletal muscles. The first neuron is called the upper motor neuron and its cell body is in the precentral gyrus. The second neuron is in the anterior gray horn of the spinal cord at the level of the spinal nerve. This is called the lower motor neuron. The cerebellum communicates with lower motor neurons indirectly through the extrapyramidal system. The postcentral gyrus and dorsal root ganglion are for neurons involved in sensory pathways.
You are carrying a couch into your friend's new apartment when another friend jumps on the couch. Why do you suddenly drop it despite the desire not to?
Reflexive muscle relaxation due to the tendon reflex
Which of the following acts as a site of skeletal muscle attachment for the eye?
Sclera
How does position information reach the unconscious motor centers of the brain?
Spinocerebellar pathways Correct! The cerebellum is an unconscious motor processing center. One of its roles is to compare planned motor information from the premotor cortex with actual body position - to do this, it needs to know your actual body position. Some position information reaches the cerebellum from the eyes and the inner ear, but much of it comes from position receptors in the body's muscles/joints. Position information from below the head and neck reach the cerebellum by way of the spinocerebellar pathways. Spino if for spinal cord, cerebellar, well, I think you know. The spinothalamic pathway goes from the spinal cord to the thalamus (ascending information), ultimately terminating in the postcentral gyrus of the parietal lobe of the cerebrum. This information is consciously perceived. The posterior-column medial lemniscus pathway goes from the spinal cord to the brain (ascending information), ultimately terminating in the postcentral gyrus of the parietal lobe of the cerebrum. This information is consciously perceived.
Suppose I hand you a section of the spinal cord (I carry them in my pockets). I tell you it is from the T4 segment. What neuron cell bodies would be located in the lateral gray horns?
Sympathetic preganglionic cell bodies Correct! The cell bodies of preganglionic neurons are located in the CNS. (Postganglionic cell bodies are in the autonomic ganglia out somewhere in the body.) The sympathetic preganglionic neurons only emerge from T1-L2/3 levels of the spinal cord; this is why the sympathetic branch is called the thoracolumbar division. Parasympathetic preganglionic cell bodies will be found only in the brain stem or in S2-S4 of the spinal cord.
Which of the following is an ipsilateral polysynaptic spinal somatic reflex that regulates muscle tension protectively?
Tendon reflex Correct! Reflexes can be innate - meaning that they are pre-programmed neural networks that generate specific motor responses to specific stimuli. They are specific because they are composed of certain neurons arranged in genetically determined pathways. All the spinal reflexes we discuss in lecture are innate reflexes - stretch, tendon etc. Learned reflexes refer to neural pathways that you have built based on experience - really they are memories. The sensory neurons communicate with interneurons which then communicate with motor neurons. These pathways have been reinforced with more learning and experience such that the responses occur without your consciously, deliberately choosing to create a motor effect (such as riding a bike). As a teacher, it is my goal that all your content acquisition becomes reflexively accessed, but I must concede that this is a lofty goal. Creating learned reflexes really requires neuron pathway creation and modulation, which requires neurons releasing more neurotransmitter, building more chemically gated channels/receptors and growing more dendrites/connections. We will discuss the mechanics of learning in the near future. Spinal reflexes feature the spinal cord as the integration (processing) center of the reflex arc. Cranial reflexes use the brainstem as the processing center. Somatic refers to skeletal muscle and not visceral (gut, heart) muscle. Ipsilateral means that the neural connections are all occurring on the same side of the body, contralateral means they involve neurons on both sides of the body. Polysynaptic reflexes involve more than just the sensory and motor neurons (they also involve interneurons) and feature more than one synapse in the reflex arc. The tendon reflex involves an interneuron in the spinal cord, neurons all on the same side of the body and skeletal muscles.
Where would you find the Leydig cells?
Testes Right! The Leydig cells produce testosterone under the influence of LH from the anterior pituitary. They are located in the testes, between the seminiferous tubules and also called interstitial cells. The seminal vesicles are accessory glands located posterior to the urinary bladder. The corpora cavernosa are erectile tissues of the penis. The corpus luteum is in the female.
Where would you find the Leydig cells?
Testes Right! The Leydig cells produce testosterone under the influence of LH from the anterior pituitary. They are located in the testes, between the seminiferous tubules and also called interstitial cells. The seminal vesicles are accessory glands located posterior to the urinary bladder. The corpora cavernosa are erectile tissues of the penis. The corpus luteum is in the female.
Which of the following is an important relay station traveling to the cerebral cortex?
Thalamus
Testosterone causes sperm production and is regulated by typical negative feedback. What would be the effect of increased exogenous testosterone? (Exogenous means the testosterone is coming from an external source and is not being produced by the body.)
The body will make less testosterone and fewer sperm Right! If you receive injections of testosterone, the levels of testosterone will elevate in your blood. This will have a negative feedback effect on the hypothalamus causing it to release less GnRH. GnRH causes the release of FSH & LH from the anterior pituitary; FSH stimulates spermatogenesis and LH stimulates testosterone production. When testosterone levels rise, less GnRH is released, less FSH and LH are released and the testes will not be stimulated to make testosterone or sperm. Your body does not discriminate between natural sources of testosterone and those injected. Interestingly, there is some current research investigating the effects of injectable hormones that regulate spermatogenesis without affecting secondary testosterone effects, like muscle mass and libido. This could signal the advent of hormonal birth control for men.
Using Figure 1, which of the following synapses would you expect to find in "P"? sensory posterior gray horn
The first synapse in the spinothalamic pathway
Using the Graph, what would happen if you stimulated the neuron with a very large EPSP (of short duration) right at the end of time "V"? end of dep?
The graph would not change
Using the Graph, where on the neuron was this trace recorded?
The initial segment of the axon
What is the role of the ciliary body?
To change the shape of the lens Correct! The ciliary body is part of the uvea (vascular tunic) but is composed of smooth muscle. Because the ciliary body is also attached by the suspensory ligaments to the lens, whenever the ciliary body muscles contract/relax, the ligaments slacken or tighten, respectively, and the lens changes shape. This shape change allows you to focus light onto the fovea of the retina. While the ciliary body is part of the uvea, its particular role is not to provide blood supply to the retina; blood supply is the job of the choroid or the vessels entering through the optic cup. The choroid is the posterior section of the uvea and the ciliary body is the anterior section. The sclera provides a site for extrinsic eye muscle attachment and is part of the fibrous tunic of the eye.
What is the role of the sodium-potassium pumps on the neuron cell membrane?
To move sodium against its concentration gradient To move potassium against its concentration gradient To establish the proper ionic concentrations of sodium and potassium across the cell membrane All of the above Correct! The Na+/K+ pump uses ATP to pump 3 Na+ ions out of the cell and 2 K+ ions into the cell. Because it uses energy to move the ions, it does not rely on diffusion for ion movement - meaning, it can push ions uphill against their concentration gradient. In doing this, it actually establishes the concentration gradient of these ions across the cell membrane and then re-establishes it after signals (action potentials) pass through the cell. This is an essential component to neuron function. Without the concentration gradients created and maintained by the Na+/K+ pumps, there could be no action potential.
You are having dental surgery performed. What cranial nerve is numbed (anesthetized) by the dentist prior to the procedure?
Trigeminal (V) Right! The trigeminal nerve (V) is the nerve that provides sensation to the skin of your face, teeth, nasal and oral cavities. A particular branch for the upper (maxillary division, superior alveolar nerve, for those interested) or the lower (mandibular division, inferior alveolar nerve, for those interested) will be numbed by dentists so that you do not feel their working. The trigeminal is the one that also detects the texture of foods in the oral cavity and stimuli in the nasal cavity that result in sneezing. Smelling is through the olfactory nerve (CN I). The facial nerve (VII) is important for muscles of facial expression. The vagus nerve (X) is important for visceral regulation during rest and digest activities.
A single neuron can exists partially in the PNS and partially in the CNS.
True
True or False? The brain has a very high metabolic rate.
True
In terms of generating a depolarizing or hyperpolarizing graded potential on a postsynaptic cell, what do you think will be the most important factor?
Type of ion channel opened Correct! Sometimes a given neurotransmitter can bind to a K+ chemically gated channel and sometimes the same neurotransmitter can bind to a Na+ chemically gated channel. This happens with acetylcholine in the heart versus in the small intestine. Therefore the same neurotransmitter can generate a hyperpolarization if it opens the K+ channel or a depolarization if it opens the Na+ channel. In these cases, the sensitivity and structural make up of the postsynaptic cell really determines if the neurotransmitter will excite (depolarize) or inhibit (hyperpolarize) the postsynaptic cell. It is more important to know the type of channel that opens (in terms of ion allowed to move) than the specific identity of the neurotransmitter. Width of the cleft may affect signal transmission - if the cleft it too big, the neurotransmitter cannot reach the targets. However, this is not something that usually varies among targets and neurons. Voltage gated channels do not bind neurotransmitter - only chemically gated channels can. For this question, you received full credit for any answer (unless it was that voltage gated channels bound neurotransmitter) because valid arguments could be made. No valid argument exists for the voltage gated channel binding neurotransmitter - chemically gated channels bind NT.
Using the Graph, you would expect membrane potential at time ____ to be higher ____.
V; in response to a greater stimulus
Athletes competing in some contact sports like football occasionally damage their brachial plexus when it is compressed by a hard hit. Which of the following would most likely indicate a brachial plexus injury?
Weakness or difficulty moving the upper limb
Which of the following most directly allows you to comprehend simple verbal or written commands?
Wernicke's area Correct! The Wernicke's area is a region of the cerebral cortex encompassing parts of the parietal, occipital and temporal lobes. When language is spoken, the sounds travel to the primary auditory cortex in the temporal lobe and then are relayed to the auditory association areas; in the association areas the sounds are identified as language (instead of music). When written words are read, the visual information is sent to the primary visual cortex in the occipital lobe and then relayed to the nearby association area; here, the visual information is interpreted as the shapes that make words. From these regions of the brain, information is then sent to the Wernicke's area. When the information is relayed to the Wernicke's area, you become fully able to comprehend that which you saw or heard. If a response is required, you will form the response here, but to speak it, you need to send information to the Broca's area. The Broca's area is the motor speech association area of the premotor cortex (frontal lobe, just anterior to the precentral gyrus). To speak, the motor signals are formulated here and then sent to the appropriate neurons of the precentral gyrus; the neurons in the precentral gyrus control your tongue, pharyngeal muscles and respiratory muscles to form words. In short, Broca's is the motor planning area for speech, not the interpretive area*. The thalamus is important as a relay station for sensory and motor information. The prefrontal cortex influences your appreciation of consequences, personality, reasoning and judgement. Although these may seem like qualities for appropriate conversation, damage to them will not influence your ability to understand spoken or written language.* *In some cases, when words or text are very complex and ambiguous, the Broca's area and other regions of the frontal lobe can become engaged to comprehend the language. This is the amazing concept about the brain, many overlapping functions and an exception to every rule! This question with the given options is not a great test question.
Which of the following is an innate reflex that typically involves a nociceptor?
Withdraw reflex Correct! Some reflexes are important to posture and regulating muscle activation. These reflexes use proprioceptors as the sensory neuron (muscle spindles for the stretch reflex and gogli tendon organs for the tendon reflex). Visceral reflexes regulate non-skeletal muscle activity, like heart rate, digestive activity, etc. and involve chemoreceptors or stretch receptors typically. Nociceptors are pain receptors - like when you touch a hot stove, the nociceptor is activated. In the spinal cord, this sensory neuron sends information to an interneuron which then communicates with the somatic motor neurons that withdraw your hand from the painful stimulus.
Yes or No? Suppose a sensory stimulus triggers an ipsilateral reflex. Does this information also reach the brain?
Yes Right! Although sensory information will trigger a motor response without the brain being involved, the brain still becomes aware of the information. This occurs because the sensory neuron branches. One branch may lead to the reflex motor neuron, but another will carry information up to the brain. The pathway that carries this information up to the brain involves more synapses than the reflex component. This is why the sensory information seemingly reaches your consciousness well after the motor response has already occurred.
You are distracted by Benny the Beaver while at the baseball game, and a fly ball hits you in the head. When you recover consciousness, you cannot recall what Benny looks like. What best explains only this deficiency?
You damaged a portion of your occipital cortex
Using Figure 1, suppose this is spinal segment C8. How would damage to "Q dorsal root" at only C8 affect you?
You would lose sensation in some cutaneous regions of the upper limb
How would damage to the left posterior column affect you?
You would not have conscious position awareness from the left side of your body below the damage. Correct! The posterior column is in the white matter of the posterior region of your spinal cord. It carries fine touch, conscious proprioception (muscle, joint position), vibration and pressure information from the same side of the body. The first order neuron axons make up the posterior column. Because the posterior column is made of first order neurons, they have not yet crossed the body. Therefore, damage to the left posterior column interrupts signal transmission (of specific information) from the left side of the body. The spinothalamic carries pain, temperature and some pressure information. It is made of different neurons in series. The first order neuron synapses in the posterior gray horn with the cell body of the second order neuron (gray horn of same side as sensory neuron). From here the second order axon crosses over to make up the spinothalamic (anterolateral) tracts/pathways. Damage to the left spinothalamic tracts would interfere with signal transmission of pain, temperature, crude pressure from the right side of the body.
In the female, hormones from the ________ bind to receptors on the ____________ causing the _____________.
anterior pituitary; ovary; ovarian cycle Yes! The ovarian cycle describes the events that occur in the ovary each month. Under the influence of anterior pituitary hormones (FSH & LH), the follicle and egg develop during the follicular phase. During the luteal phase, the corpus luteum is stimulated by LH. Together the effects of the anterior pituitary hormones affect the activities of the ovary because the cells of the ovary have receptors for FSH & LH. The uterine cycle is caused by hormones from the ovary. Estrogen and progesterone are produced by cells of the follicles or the corpus luteum, structures that are and remain in the ovary. The uterus has receptors for estrogen and progesterone and is therefore affected by these hormones. The posterior pituitary hormones do not regulate uterine or ovarian cycles. The uterus does not produce hormones.
The basal ganglia:
are involved in procedural (skill) memory. Yes! The basal nuclei (or basal ganglia) are a group of subcortical nuclei of gray matter found deep within the cerebral white matter. The roles of the basal ganglia overlap with those of the cerebellum. They influence conscious motor pathways indirectly, playing an important role in starting, stopping and monitoring the intensity of learned or repetitive movements.
Which connect the premotor cortex to the primary motor cortex in the right hemisphere?
association fibers Right! Association fibers are tracts of white matter that connect cortical ares within a cerebral hemisphere. Projection fibers unite the cerebral cortex with lower parts of the brain and the spinal cord which commissural fibers connect the two cerebral hemispheres. Nerves are bundles of axons, but they are found in the PNS.
Damage to the ____ can result in irreversible coma.
brainstem
To create sleep, neurons in the ____ must be inhibited
brainstem
For you to be fully consciously aware of body activities or stimuli in the environment, the ____________ must receive or initiate neural signals.
cerebral cortex
By mass, the ____ is the largest part of the brain.
cerebrum
In the uterine cycle, during the proliferative and secretory phases the ____ thickens and prepares for potential implantation of an embryo. During the menstrual phase, the ____ is shed.
endometrium; endometrium
In the female, urine and gametes share a pathway out of the body.
false
True or False? The spinal cord runs the entire length of the vertebral column.
false Correct! The spinal cord runs from the brain to the level of the first or second lumbar vertebrae. From there, nerve roots extend down the rest of the vertebral canal (these nerves make up the cauda equina). The spinal cord proper does not run the entire length of the vertebral column.
When a sensory receptor detects a large temporary stimulus, the sensory neuron:
fires many APs frequently
When a sensory receptor detects a large temporary stimulus, the sensory neuron:
fires many APs frequently Correct! When a stimulus is very big, the neuron fires many action potentials in a short period of time (coding for stimulus intensity with AP frequency). APs are all or none events that do not change shape or intensity because their shape is determined by events at voltage gated channels. These voltage gated channels only stay open as long as they do and usually allow the same ionic flow during each event. This results in the same membrane potential changes each time threshold is reached. When stimuli are very large or sustained, they result in the membrane reaching threshold for a sustained period of time. Because the membrane is at threshold, the voltage gated channels open again once they are able (after the absolute refractory period). In the situation described here, the sensory neuron is firing many APs to the next neuron in the CNS. The CNS neuron is receiving neurotransmitter from a single presynaptic neuron (the sensory neuron) and that neurotransmitter is being released frequently (for each AP fired). The effect of the multiple events are adding to one another on the postsynaptic cell to create a much larger change in the membrane potential of the postsynaptic cell. These events are close to one another in time and their effects are additive; this event is called temporal summation.
During the ____ phase of the ovarian cycle, ____ simulates development of ____.
follicular; FSH; follicle cells
Where do terminal ends synapse with cell bodies in the central nervous system?
gray matter
The ____ is vitally important because of its indirect control over body temperature, heart rate, blood pressure and digestive function.
hypothalamus
Which part of the endocrine system is most appropriately called the "master gland"?
hypothalamus Most correct! While the anterior and posterior pituitary release hormones necessary for homeostasis, they only do under the direction of the hypothalamus. The thyroid gland releases a hormone that has widespread effects on virtually every cell in the body, but again, its activity is regulated by a hormone from the ant. pit, who is regulated by the hypothalamus. The best answer here is the hypothalamus.
ADH is produced in the _______________ and released to the blood from the _____________.
hypothalamus; posterior pituitary Sehr gut! Anitdiuretic hormone (ADH) is essential to your normal blood osmolarity (salt/water balance). It is made by neurons in the hypothalamus. These neurons have their cell bodies in the hypothalamus but their axons extend down to the posterior pituitary. Because all of the cellular machinery responsible for ADH production is located in the cell bodies, ADH is made in the hypothalamus. However, because the terminal end that releases the ADH to the blood is located in the posterior pituitary, the hormone is actually released from the post. pituitary.
During the repolarization phase of the action potential (at mid point of repolarization):
membrane permeability to potassium is higher than at rest. Right! During the repolarization phase of the action potential, the membrane potential is decreasing from peak values back towards resting levels. During this time, the voltage gated potassium channels are open and potassium ions are diffusing out of the cell. The loss of potassium from the interior removes positive ions, leaving the interior increasingly more relatively negative and creating the repolarizing slope shown in an AP graph. At this time, because the potassium channels are opened, we say that the membrane is more permeable to potassium than when the channels are closed (they are closed at rest). Membrane permeability to ions = number of channels available for ions movement. The sodium-potassium pumps are always active. The membrane is not less permeable (than at rest) to either sodium or potassium at this time - for it to be so, some of the leak channels normally opened during rest would have to be closed.
Which of the following would you find myelinating the axons of CN (10)?
oligodendrocytes?
Potassium ions have a ____ charge and ____ a neuron when they flow down their concentration gradient.
positive; exit Correct! Potassium ions are positively charged (K+) and are more concentrated inside the neuron due to the action of the sodium/potassium pump. When they are able to cross the cell membrane through a channel, they flow passively down their concentration gradients from where they are more concentrated to where they are less concentrated, thus exiting the cell.
Releases hormone that promotes milk ejection in nursing females
post p
In a resting neuron, ____ are important for creating and maintaining ionic gradients across the membrane.
pumps
In general, sympathetic preganglionic neuron axons are relatively ____ and postganglionic neuron axons are relatively ____.
short; long
Match the following structures to their function. Broca's area Wernicke's area Postcentral gyrus Somatosensory association area Prefrontal cortex Premotor cortex Primary motor cortex
speech production language comprehension sensory receptive area for touch interprets touch stimuli involved in decision making, complex though, personality creates motor program or plan executes motor program
Assuming otherwise equal factors, the stretch reflex is faster than the flexor withdrawal reflex because:
the stretch reflex is monosynaptic and the flexor withdrawal reflex is not.
When the appropriate part of the axon membrane reaches a certain transmembrane potential...
the voltage gated channels begin to open.
The more pleasurable or painful an experience, the more likely it is to create a long term memory.
true
True or False? Leak channels and sodium-potassium pumps are present on the cell body, dendrites, axon and terminal ends of the neuron cell membrane.
true Correct! The leak channels and sodium-potassium pumps are responsible for creating and maintaining the cell membrane resting potential. Because the transmembrane potential exists at all parts of the cell membrane, they are located throughout the cell membrane and all its parts (cell body, dendrites, axon, terminal end).
True or False? At rest, the interior of a neuron has more potassium ions than the exterior, but is relatively negative compared to the outside of the cell.
true Correct! The sodium/potassium pumps on every cell establish a high concentration of potassium inside cells and high concentration of sodium outside of cells. This is true of neurons as well. Each turn of the sodium-potassium pump moves 3 positively charged sodium ions out of cells and adds 2 positively charged potassium ions into cells. This action contributes to the relatively negative interior of neurons despite the presence of so many positively charged ions. Additionally, the interior of neurons has negatively charged proteins contributing to the relatively negativity (these proteins are not present on the exterior). However, the most important component of the negative interior is the constant outward leakage of potassium ions through membrane leak channels for potassium. When these ions leak out, a positive ion leaves the interior and is added to the exterior, thereby making the interior relatively negative. While there is some inward leakage of positive sodium, it is 100X less than the outward leakage of potassium and overall does not make the interior positive during rest
The ___________ are fluid filled cavities in the brain that are continuous with one another and the central canal of the spinal cord.
ventricles