Anatomy Lecture Final Term 2 (quizzes)
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 Right! Depolarizing graded potential bring the neuron transmembrane potential above resting values towards (or above) threshold values. Once threshold is reached at the trigger zone, the voltage gated channels open and an action potential can be generated. Hyperpolarizing graded potentials lower the membrane potential away from threshold and make a neuron less likely to fire an action potential. When depolarizing graded potentials are created in response to a neurotransmitter binding on a post synaptic neuron, we will call them excitatory postsynaptic potentials (EPSP) because they bring the post synaptic neuron closer to threshold and more likely to fire an AP. When hyperpolarizing postsynaptic potentials are generated on the postsynaptic neuron, we call them inhibitory postsynaptic potentials (IPSPs) and make a neuron less likely to fire an action potential. Another term you will get to know is: subthreshold stimuli. These are depolarizing graded potentials that do not bring the transmembrane potential at the trigger zone to threshold and therefore do not open the voltage gated channels responsible for action potential generation.
Which of the following hormones will bind to an intracellular receptor? A fat soluble hormone that is not attached to blood transport protein A fat soluble hormone that is attached to a blood transport protein A water soluble hormone that is not attached to a blood transport protein A water soluble hormone that is attached to a blood transport protein
A fat soluble hormone that is not attached to blood transport protein Right! Fat soluble hormones diffuse through the cell membrane, bind to an intracellular receptor and require a blood transport protein to get around the body. However, in order for the fat soluble hormone (like thyroxine, estrogen, testosterone) to affect a cell, the blood transport protein must release the hormone. Water soluble hormones do not require transport proteins but must bind to a cell membrane receptor for effect.
Which of the following hormones will bind to an intracellular receptor? A fat soluble hormone that is not attached to blood transport protein A fat soluble hormone that is attached to a blood transport protein A water soluble hormone that is not attached to a blood transport protein A water soluble hormone that is attached to a blood transport protein
A fat soluble hormone that is not attached to blood transport protein Right! Fat soluble hormones diffuse through the cell membrane, bind to an intracellular receptor and require a blood transport protein to get around the body. However, in order for the fat soluble hormone (like thyroxine, estrogen, testosterone) to affect a cell, the blood transport protein must release the hormone. Water soluble hormones do not require transport proteins but must bind to a cell membrane receptor for effect.
What directly causes a chemically gated channel to open?
A neurotransmitter binding on the chemically gated channel Correct! Chemically gated channels are membrane proteins that open when a chemical binds to a receptor on the channel. The chemical that causes them to open, if released from a neuron, is called a neurotransmitter. 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. Mechanically gated channels open when the surrounding membrane (or channel) is physically changed (deformed). Regardless of the type of gated channel, channels are specific for the ions they allow to cross the cell membrane and only allow ions to cross the cell membrane using their diffusion gradients. Meaning, they only allow sodium to enter the cell because there is so much sodium outside of cells compared to inside of cells. The reverse is true for potassium.
Which of the following will cause a graded hyperpolarization on a postsynaptic neuron?
A neurotransmitter binding to a chemically gated potassium channel 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).
When you sense rotation by the equilibrium receptors of the inner ear, why do your eyes move? Because sensory information from the cristae/cupulae is sent to the neurons of the brainstem that synapse with cranial nerves to the eye muscles. Because sensory information from CN I is sent to the the centers of the brain that control eye movements. Because sensory information from parasympathetic neurons is also sent to the the centers of the brain that control eye movements. Because sensory information from sympathetic neurons is also sent to the the centers of the brain that control eye movements.
Because sensory information from the cristae/cupulae is sent to the neurons of the brainstem that synapse with cranial nerves to the eye muscles. The cupula & crista are located in the base of the semicircular canals and contain hair cells that detect rotational movements. Information from these receptors is sent via the vestibular branch of the vestibular cochlear nerve (CN VIII) to the brain. Information arrives in the vestibular nuclei where it can then be sent to other regions of the brain. Some information is sent to nuclei in the brainstem (superior colliculi of midbrain) that contain the motor neuron cell bodies for CN III, IV & VI (the ones that control eye movements). CN I does not relay not equilibrium information. Sympathetic and parasympathetic neurons do not carry sensory information - only motor
When you sense rotation by the equilibrium receptors of the inner ear, why do your eyes move? Because sensory information from the cristae/cupulae is sent to the neurons of the brainstem that synapse with cranial nerves to the eye muscles. Because sensory information from CN I is sent to the the centers of the brain that control eye movements. Because sensory information from parasympathetic neurons is also sent to the the centers of the brain that control eye movements. Because sensory information from sympathetic neurons is also sent to the the centers of the brain that control eye movements
Because sensory information from the cristae/cupulae is sent to the neurons of the brainstem that synapse with cranial nerves to the eye muscles. The cupula & crista are located in the base of the semicircular canals and contain hair cells that detect rotational movements. Information from these receptors is sent via the vestibular branch of the vestibular cochlear nerve (CN VIII) to the brain. Information arrives in the vestibular nuclei where it can then be sent to other regions of the brain. Some information is sent to nuclei in the brainstem (superior colliculi of midbrain) that contain the motor neuron cell bodies for CN III, IV & VI (the ones that control eye movements). CN I does not relay not equilibrium information. Sympathetic and parasympathetic neurons do not carry sensory information - only motor.
Based on what we discussed in lecture and what you know about our physiology, why might chronically stressed individuals be more susceptible to infection? Because their immune systems are suppressed Because they are at increased risk of bacterial infection due to blood brain barrier non-functionality Because their RAS does not filter out harmful bacteria
Because their immune systems are suppressed Correct! Chronic stress causes the release of cortisol from the adrenal cortex. Beyond its glucose regulatory effects, cortisol suppresses the immune system by reducing inflammation and the effect of immune cells. With a reduced immune system function, people are more likely to become afflicted by pathogens in the environment or their own bodies. While the brain may not be functioning optimally under stressful situations and this may cause people to make unwise and dangerous decisions, it is not likely a cause of blood-brain barrier malfunction. The RAS does not have an immune function. The RAS is a filter for sensory information and is charged with electrically exciting the cerebral cortex.
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.
You would NOT expect to find a lateral gray horn in which of the following spinal cord segments? C3 T5 L1
C3 Correct! Preganglionic sympathetic neuron cell bodies are found in the ventral horns of thoracic and lumbar spinal cord segments. Since there are no autonomic neuron cell bodies in the cervical spinal segments, you would not expect to see lateral gray horns in those regions of the spinal cord.
For you to be fully consciously aware of sensory stimuli in the environment, the ____________ must receive neural signals.
Cerebral cortex Brain stem Diencephalon Cerebellum Hypothalamus 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.
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. The choroid plexuses are where CSF is made in each ventricle.
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 1 3 eleventy billion
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.
Which of the following is an innate reflex that typically involves a nociceptor? Tendon reflex Withdraw reflex Stretch reflex Any visceral 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.
In certain conditions, some facial muscles cannot contract. What would cause this? Defect of facial nerve Defect of trigeminal nerve Defect of vagus nerve Defect of cervical spinal nerves
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.
Which of the following is important in determining your motivational drives, learning and emotions? Limbic system Occipital lobe Brainstem Precentral gyrus
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.
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 Cranial nerves (CNs) I, V & VII Cranial nerves (CNs) IX, X & XII
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 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.
How does subconscious information reach lower motor neurons (what are the downward pathways that carry this information)?Extrapyramidal pathways Corticospinal pathways Pyramidal pathway Direct somatic motor pathways
Extrapyramidal pathways 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.
_________ 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.
_________ hormones travel in the blood _________ and bind to intracellular receptors. Correct! Fat soluble; bound to carriers (mostly) Water soluble; freely Water soluble; bound to carriers (mostly) Fat soluble; freely
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.
What cells carry visual information to the brain? Ganglion cells Photoreceptors Bipolar cells Horizontal cells
Ganglion cells 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 White matter Nerves Meninges
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.
Where do terminal ends synapse with cell bodies 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.
Which of the following are the most important components of an acute stress reaction? Hypothalamus & adrenal medullae Hypothalamus, anterior pituitary and adrenal cortex Pancreas & parathyroid glands Posterior pituitary & hypothalamus
Hypothalamus & adrenal medullae 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 CRH Increased GnRH Increased TRH Increased GHRH
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.)
Where does a neurotransmitter usually bind to chemically gated channels on postsynaptic neurons?
On the dendrites and cell body Correct! Chemically gated channels bind neurotransmitter and usually located on the receptive regions of neurons. In multipolar neurons, these are the dendrites and cell body. The axon of neurons contains a high abundance of voltage gated channels.
Where would you find the Leydig cells? Testes Corpora cavernosa Corpus luteum Seminal vesicles
Testes 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.
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 testes will produce more testosterone The posterior pituitary will release more oxytocin The body will make less testosterone and fewer sperm
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.
Which is true of both the olfactory and gustatory receptors? They both require the chemical that stimulates them to be dissolved in water/mucous. They are both proprioceptors. They are never replaced. Only gustatory receptors contribute to taste sensations.
They both require the chemical that stimulates them to be dissolved in water/mucous. Correct! The olfactory and gustatory receptors are chemoreceptors. They bind chemicals that lead to depolarizations and ultimately, action potentials that are sent to the brain for perception. They both require that their stimuli are dissolved in mucous (or fluid) to be detected. They also are both capable of regeneration - within about 1-2 weeks you have replaced all your taste buds and within 1-2 months you have replaced all your olfactory receptors. Both olfactory and gustatory receptors contribute to the sensations of taste. It is estimated that about 70-80% of taste is smell because both receptors trigger regions in centers of the brain.
True or False? The cells that detect the effects of head motion are the same type of cells that detect auditory stimuli.
True Hair cells are mechanoreceptors that detect the effects of head motion and sounds. They are located in the maculae of the vestibule, the cupula/crista of the semicircular canals and the cochlea. They each relay information to neurons of the vestibulocochlear nerve that is sent to the brain for processing. Processing for sound occurs in a different region than processing for equilibrium.
Which of the following most directly allows you to comprehend simple verbal or written commands? Wernicke's area Broca's area Thalamus Prefrontal cortex
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.
In the female, hormones from the ________ bind to receptors on the ____________ causing the _____________. anterior pituitary; ovary; ovarian cycle ovary; ovary; ovarian cycle posterior pituitary; uterus; uterine cycle uterus; uterus; uterine cycle
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.
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.
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.
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.
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.
Which of the following is essential to consolidation of fact (declarative) memories? hippocampus medulla oblongata spinocerebellar pathway
hippocampus Correct! Consolidation refers to the conversion of short term memories to long term memories. The hippocampus is essential to this function. During long term memory formation, hippocampal neurons facilitate neural pathways leading to rapid transmission of signals along specific neural traces. A memory is a stimulus that triggers signal transmission along this specific neural path. When the hippocampus is removed, individuals cannot form long term memories (a condition called anterograde amnesia).
Which part of the endocrine system is most appropriately called the "master gland"? hypothalamus anterior pituitary posterior pituitary thyroid
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 posterior pituitary; posterior pituitary anterior pituitary; posterior pituitary posterior pituitary; anterior pituitary
hypothalamus; posterior pituitar 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.
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.
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.
True or False? Some olfactory and gustatory stimuli (odorants/tastants) trigger action potentials in low concentrations, while other odorants/tastants trigger action potentials only in high concentrations.
true Correct! You inherently know this - think of a very bad odor, like rotting food or cigarette smoke. You can detect these odors although very little of them many be present. It is similar for the chemical they put in natural gas that is piped into your home. These odorants trigger the olfactory receptors to generate action potentials when just a few molecules are present (although with natural gas, 1 in 1000 people cannot detect that odor). Sometimes we can adapt to these noxious fumes - like smokers who gradually destroy their olfactory receptors with the toxins in cigarette smoke (not true adaptation, but the same effect), or decreased production of the receptors on the receptor cells for that odorant/tastant or our brain activates GABA secreting neurons in the olfactory pathway to inhibit signal transmission - but for others, we cannot adapt. Other odorants/tastants require more of the molecules to be present to initiate an effect in the receptor cells. Because these modalities are mediated by a chemically gated channel, you can think of the odorant/tastant like we think of neurotransmitters on a postsynaptic cell. Bigger graded potentials are generated when there are more receptors for the neurotransmitter or the neurotransmitter is present for longer. Odorants/tastants that bind for long periods or find more receptors can have a big effect despite have few molecules present. The other factors that affect an odorant's ability to trigger awareness is the odorant's ability to dissolve in your nasal mucosa and find the olfactory receptor cells. If you have a very dry nose or an overly mucous filled nose (stuff nose), odorants cannot reach the receptors.
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, 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).
Where must threshold be reached to send a signal all the way down the length of the neuron?
At the trigger zone 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.
How do you know where your right foot is with your eyes closed?
Because proprioceptive information is sent to the cerebral cortex
What can accurately be described as the location of equilibrium receptors? The vestibular apparatus The mesencephalon The reticular activating system The cochlea
The vestibular apparatus Right! The vestibular apparatus includes the regions of the inner ear that contain equilibrium receptors. Specifically, the vestibular apparatus includes the maculae in the vestibule and the crista/cupula of the semicircular canals. The cochlea contains hair cells that respond to sound, not equilibrium. The mesencephalon contains reflex centers of the midbrain for visual information and CNs III, IV & VI. Equilibrium information is also sent here. The reticular activating system (RAS) is a series of neurons in the brainstem that arouse the cerebral cortex.
what type of stimulus would generate another action potential during depolarization phase
none
What is the role of the sodium-potassium pumps on the neuron cell membrane?
1. To move sodium against its concentration gradient 2. To move potassium against its concentration gradient 3. To establish the proper ionic concentrations of sodium and potassium across the cell membrane
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
To create a graded hyperpolarization 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
Why are sodium ions more concentrated outside of cells?
Because sodium ions are actively transported out of cells
Which of the following structures is NOT fluid filled in a healthy individual?
Bony labyrinth In a healthy ear, there should be no fluid in the middle ear. However, the bony labyrinth is filled with perilymph and the semicircular canals and vestibules are both filled with endolymph.
For you to be fully consciously aware of body activities or stimuli in the environment, the ____________ must receive or initiate 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
what contributes most to the rapid change in the transmembrane potential during the repolarization phase
Decreased permeability of the cell membrane to sodium.
Which of the following most accurately describes what is happening in a resting neuron?
During rest, all ions are moving across the cell membrane passively. 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.
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 Estrogen & progesterone GnRH & inhibin TRH & TSH
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.
The resting membrane potential exists only on the cell body and dendrites
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.
Damage to the cerebellum would most likely result in: Correct! Inability to walk with coordination Inability to control heart rate Inability to control respiratory rate Inability to maintain blood pressure
Inability to walk with coordination Correct! The cerebellum is a processing center for motor activities; in particular for skeletal muscle coordination. The cerebellum allows skeletal muscles to act together and in sequence to create smooth, fluid motions. It also is a site where equilibrium is controlled because it coordinates input from the equilibrium sensors in the body (in ear) with information about the position of the body (from proprioceptors). The brainstem is responsible for all the other activities listed here.
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. Interneurons in the spinal cord carry motor information towards the brain and sensory information away from the brain. There is a central core of white matter surrounded by gray matter. The posterior regions of the white and gray matter carry primarily motor information and the anterior regions carry primarily sensory information.
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.
Which of the following would most likely inhibit the opening of voltage gated channels on the axon? Multiple IPSPs in rapid succession at the same location on a dendrite far from the trigger zone. Multiple EPSPs in rapid succession at the same location on a dendrite far from the trigger zone. One EPSP on a dendrite near the trigger zone. Briefly opening a sodium chemically gated channel on a dendrite far from the trigger zone.
Multiple IPSPs in rapid succession at the same location on a dendrite far from the trigger zone.
True or False? All the hormones from the anterior pituitary are regulated by some hormone from the hypothalamus. (not the same hypothalamic hormone for all ant pit hormones)
Right! All the hormones from the anterior pituitary are regulated by hormones from the hypothalamus - the hypothalamic hormones reach the anterior pituitary via the hypophyseal portal system, a special blood network between the hypothalamus and the anterior pituitary. Although negative feedback can inhibit the release of anterior pituitary hormones, this factor is in addition to the regulatory hormones from the hypothalamus.
Yes or No? Suppose a sensory stimulus triggers an ipsilateral reflex. Does this information also reach the brain?
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.
Which of the following does NOT cause the release of a hormone from an endocrine organ? Somatic motor neuron stimulation Levels of circulating ions Another hormone Neural reflex arc
Somatic motor neuron stimulation 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.
Which of the following is an ipsilateral polysynaptic spinal somatic reflex that regulates muscle tension protectively? Tendon reflex Crossed extensor reflex Stretch reflex Any visceral reflex
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 of the following is an important relay station traveling to the cerebral cortex? Thalamus Hippocampus Pineal gland Primary area
Thalamus
What is the role of the ciliary body? To change the shape of the lens To change the shape of the cornea To provide nutrients to the retina To provide a site for extrinsic eye muscle attachment
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.
You are having dental surgery performed. What cranial nerve is numbed by the dentist prior to the procedure? Facial (CN VII) Trigeminal (V) Vagus (X)
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.
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 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.
Which of the following neuronal pathways would transmit its impulse to the effector slowest? (Assume equal axon diameter and pathway length.)
Unmyelinated axon - synapse - unmyelinated axon - synapse - unmyelinated axon - effector
Yes or No? Suppose a sensory stimulus triggers a spinal nerve reflex. Does this information also reach the brain?
Yes 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.
Which of the following will produce an IPSP? Acetylcholine Epinephrine NO Dopamine
You cannot tell from the information given - the effect of a neurotransmitter depends on the type of channel it causes to open.
The basal ganglia: relay sensory information to the cerebral cortex. comprise tracts of white matter in the cerebrum. are found in the brainstem. are involved in procedural (skill) memory.
are involved in procedural (skill) memory. Yes! The basal ganglia (or basal nuclei) 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 cerebellus. They influence conscious motor pathways indirectly, playinig an important role in starting, stopping and monitorying the intensity of learned or repetitive movements.
By mass, the ____ is the largest part of the brain. Cerebrum Cerebellum Brainstem Diencephalon
cerebrum Right! Perhaps a little more straightfoward than I usually ask, but the cerebrum is very well developed in humans. We use our cerebrum for higher level processing and conscious activities. If information originates in or is transmitted to the cerebral cortex, you are consciously aware of that information. We will explore the cerebrum in detail this week. The cerebellum is important for unconscious motor control. The diencephalon is a major relay station and autonomic control center. The brainstem regulates basic life functions (heart, lungs, guts).
when do the potassium voltage gated channels start to close?
hyperpolarization phase
Potassium ions have a ____ charge and ____ a neuron when they flow down their concentration gradient.
positive; exit 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.
When the appropriate part of the axon membrane reaches a certain transmembrane potential...
the voltage gated channels begin to open. Correct! The certain value of transmembrane potential that opens voltage gated channels is called threshold. When the cell membrane adjacent to voltage gated channels reaches threshold, the gates begin to open. This is the triggering of an action potential. Leak channels are always open (effectively) Chemically gated channels open when a chemical binds (neurotransmitter) The Na+/K+ pumps are always active
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
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.
