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Which part of the brain is responsible for controlling body temperature, and adjusting to external temperature conditions?
The hypothalamus is responsible for cooling and heating mechanisms in the body, and thus is the correct answer.
The cerebrum is responsible for higher brain functions, like conscious thought. The cerebellum is essential for balance and coordination. The thalamus is primarily responsible for integrating and coordinating sensory input to the brain.
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An individual presents to his physician with a complaint of "uncoordinated muscle movements." After running proper tests, the physician suspects that this individual has some degree of brain injury. Which portion of the brain is most likely to be injured?
The cerebellum is responsible for coordination and balance. Injury to the cerebellum can result in a loss of motor coordination.
The medulla oblongata controls autonomic activities, such as regulating heart and respiration rates. The hypothalamus regulates the fight-or-flight response, sex drive, thirst, and hunger. The midbrain is the center for auditory and visual signal relay to the cortex. The hippocampus functions in the retention of memories.
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Which of the following structures connects the right and left hemispheres of the brain?
The MCAT contains minimal questions regarding brain anatomy, however, you should have an understanding of a select few structures, one of which is the corpus collosum. The corpus collosum is a bundle of neurons connecting the left and right brain, allowing communication between the left and right hemispheres. If these neurons were damaged somehow, the result would be split-brain syndrome, a condition in which the two halves of the brain do not communicate with one another.
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Which section of the brain is responsible for regulating temperature?
Receptors in the hypothalamus regulate temperature by sending nerve signals to muscles and sweat glands in the body. The hypothalamus is located deep within the center of the brain, at the very top of the brain stem. The other answers are different sections of the brain responsible for other tasks. For instance, the cerebrum is the largest section of the brain responsible for memory, consciousness, language and intellect.
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Which of the following activities would you expect to be controlled by the cerebral cortex?
The cerebral cortex is also referred to as the "higher brain." It acts to process thoughts and store memories. More basic, vital activities such as heart beat and breathing are controlled by other, less developed regions of the brain. Note that the hippocampus plays a role in creating memories, but most memories are stored in the cerebrum; this is the link between long term and short term memory storage.
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An individual presents to his physician with an abnormal breathing rhythm. The physician suspects that the problem may be originating from his brain. What part of his brain is most likely not functioning properly?
The medulla oblongata is responsible for autonomic functions, such as breathing rate and heart rate regulation. Dysfunction of the medulla oblongata could result in problems with breathing rhythm.
The cerebellum is responsible for coordination and balance. The hypothalamus regulates the fight-or-flight response, sex drive, thirst, and hunger. The midbrain is the center for auditory and visual signal relay to the cortex. The hippocampus functions in the retention of memories.
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A lesion to which brain region would result in a lack of coordinated movement?
The cerebellum is responsible for the coordination of movement between the motor and sensory cortices. It helps account for movements and correct the magnitude of stimulation of skeletal muscle. The cerebellum is essential for fine-tuning functions like balance and hand-eye coordination.
The medulla, or medulla oblongata, is mainly responsible for the modulation of involuntary vital functions like ventilation rate and heart rate. The hypothalamus plays a key role in the activation of the sympathetic nervous system and also plays a key role in hunger, sexual reproduction, and endocrine function. The temporal lobe is a region of the cerebrum, and is associated with auditory and speech function as well as memory formation.
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Which is the correct order of sequences during the knee-jerk reflex?
During the knee-jerk reflex, the neural signal is initiated by the stretching of the patella tendon, which is transmitted via sensory neuron to the spinal cord. In turn, the signal is transmitted to the motor neuron, resulting in the contraction of quadriceps. Most importantly, the reflex bypasses the brain, allowing a speedy reaction of the body to the stimulus.
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A patient who is unable to modulate his own ventilation and heart rate may be suffering damage to which part of his brain?
The medulla oblongata, a part of the hindbrain, is primarily responsible for the control of ventilation and heart rate. The midbrain serves as a relay station for visual and auditory information. The cerebellum is responsible for balance and coordination. The corpus callosum is a connective tissue between the two hemispheres of the brain and allows for their intercommunication. The temporal lobes are primarily responsible for auditory processing. Therefore, the patient is most likely suffering from a damage to the medulla oblongata.
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Which of the following is part of the hindbrain?
The hindbrain consists of the pons, medulla oblongata, and cerebellum.
The cerebrum, thalamus, and hypothalamus are part of the forebrain. Broca's area is a specific region of the cerebrum dedicated to understanding language.
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Which of the following accurately describes white matter?
White matter refers to the white-colored myelin that surrounds the axons of neurons in the central nervous system. These axons are grouped together, creating distinct regions of white matter. In contrast, grey matter refers to the cell bodies of neurons in the central nervous system. The cell bodies are packed together into dense regions to create grey matter.
In a cross-section of the spinal cord, gray matter is located in the center and is surrounded by white matter.
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Your hand jerks back when you touch a hot stove. Which of the following describes the pathway of nerve impulses responsible for this reflex?
Messages are picked up by sensory neurons in the peripheral nervous system and passed to interneurons in the central nervous system; responses are passed on to motor neurons in the peripheral nervous system
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The brain is a very delicate structure with little room to move around. Surrounding the brain and the spinal cord are three protective layers in addition to the skull and the vertebral column. Directly surrounding the brain and spinal cord is the pia mater. Following the pia mater is the arachnoid mater. Between the pia mater and the arachnoid mater is the sub-arachnoid space where the cerebrospinal fluid circulates. Finally, the protective layer is the dura mater is loosely attached to the arachnoid mater but is strongly associated with the skull bone.
Depending on the type of injury, a certain type of vein and/or artery are more susceptible to injury. For example, the meningeal artery and vein run through the foramen spinosum and travel between the two layers making up the dura mater. As the artery and the vein are traveling in between the dura mater, there is a vulnerable region at the temple. A strike to the temple region could rupture these vessels and result in a epidural hematoma.
Traveling from the cerebral cortex to the venous dural sinus (located at certain regions between the two layers of the dura mater) is the cerebral vein. When an injury results in the dura mater shifting away from the arachnoid mater, the cerebral vein could rupture and lead to a subdural hematoma.
When a physician performs a lumbar puncture, he/she is extracting cerebrospinal fluid. Through which of the follow structure(s) must the needle pass?
I. Dura mater
II. Arachnoid mater
III. Pia mater
As described in the passage, the innermost layer is the pia mater, then the arachnoid space, arachnoid mater and finally the dura mater. The dura mater is the outermost layer prior to the skull/vertebral column. Therefore, during a lumbar puncture, the needle will have to pass through the dura mater first then through the arachnoid mater to get to the sub-arachnoid space.
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The central nervous system consists of the brain and the spinal cord. In general, tracts allow for the brain to communicate up and down with the spinal cord. The commissures allow for the two hemispheres of the brain to communicate with each other. One of the most important commissures is the corpus callosum. The association fibers allow for the anterior regions of the brain to communicate with the posterior regions. One of the evolved routes from the spinal cord to the brain is via the dorsal column pathway. This route allows for fine touch, vibration, proprioception and 2 points discrimination. This pathway is much faster than the pain route. From the lower limbs, the signal ascends to the brain via a region called the gracile fasciculus. From the upper limbs, the signal ascends via the cuneate fasciculus region in the spinal cord.
Which of the following sentences correctly explains what happens when a person steps on a pin?
I. Transmit to the brain rapidly
II. Will utilize the gracile fasciculus region in the spinal cord
III. Will utilize the cuneate fasciculus region in the spinal cord
Fine touch, vibration, proprioception and 2 points discrimination all utilizes the dorsal column pathway. The upper region utilizes the cuneate fasciculus in the spinal cord while the lower region depends on the gracile fasciculus. According to the passage, these sensations are of the rapid pathway whereas other sensations such as pain is not as fast. The dorsal column pathway is heavily myelinated while the pain pathway is not as myelinated.
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The central nervous system consists of the brain and the spinal cord. In general, tracts allow for the brain to communicate up and down with the spinal cord. The commissures allow for the two hemispheres of the brain to communicate with each other. One of the most important commissures is the corpus callosum. The association fibers allow for the anterior regions of the brain to communicate with the posterior regions. One of the evolved routes from the spinal cord to the brain is via the dorsal column pathway. This route allows for fine touch, vibration, proprioception and 2 points discrimination. This pathway is much faster than the pain route. From the lower limbs, the signal ascends to the brain via a region called the gracile fasciculus. From the upper limbs, the signal ascends via the cuneate fasciculus region in the spinal cord.
Patient A has a tumor in his spinal cord. He is able to feel fine touch above the waist. Below the waist he is unable to feel fine touch on either side. Where is the tumor most likely located?
I. All levels of the spinal cord
II. In the gracile fasciculus region
III. In the cuneate fasciculus region
Patient A is unable to feel fine touch below the waist. A tumor in the gracile fasciculus region will prevent the signal from below the waist to reach the brain.
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The central nervous system consists of the brain and the spinal cord. In general, tracts allow for the brain to communicate up and down with the spinal cord. The commissures allow for the two hemispheres of the brain to communicate with each other. One of the most important commissures is the corpus callosum. The association fibers allow for the anterior regions of the brain to communicate with the posterior regions. One of the evolved routes from the spinal cord to the brain is via the dorsal column pathway. This route allows for fine touch, vibration, proprioception and 2 points discrimination. This pathway is much faster than the pain route. From the lower limbs, the signal ascends to the brain via a region called the gracile fasciculus. From the upper limbs, the signal ascends via the cuneate fasciculus region in the spinal cord.
Patient A has a tumor in his spinal cord. He is able to feel fine touch below the waist. Above the waist, he is unable to feel fine touch on either side. Where is the tumor most likely located?
I. All levels of the spinal cord
II. In the gracile fasciculus region
III. In the cuneate fasciculus region
Patient A is unable to feel fine touch above the waist. A tumor in the cuneate fasciculus region will prevent the signal to travel from above the waist to reach the brain.
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When you stare directly at an object, the image focuses on what part of the retina?
The fovea centralis, also known as the focal point, is the point where an image is centered when you stare at objects. This region of the retina has a high number of cone and rod cells, and explains why we can only clearly focus on one object at a time. Only the object lined up with the fovea centralis will remain clear, while peripheral objects appear blurry.
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The cells that form myelin sheaths around axons outside of the central nervous system are __________.
It is important to read this question carefully, as it asks for the cells that form myelin sheaths around axons outside of the central nervous system. In essence, it is asking about the peripheral nervous system.
Schwann cells and oligodendrocytes both form myelin sheaths (a white, fatty substance) around axons, which act as electrical insulation and increase the speed of action potential conduction. Schwann cells perform this function for neurons in the peripheral nervous system (outside of the central nervous system), while oligodendrocytes myelinate neurons in the central nervous system.
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Prions are the suspected cause of a wide variety of neurodegenerative diseases in mammals. According to prevailing theory, prions are infectious particles made only of protein and found in high concentrations in the brains of infected animals. All mammals produce normal prion protein, PrPC, a transmembrane protein whose function remains unclear.
Infectious prions, PrPRes, induce conformational changes in the existing PrPC proteins according to the following reaction:
PrPC + PrPRes → PrPRes + PrPRes
The PrPRes is then suspected to accumulate in the nervous tissue of infected patients and cause disease. This model of transmission generates replicated proteins, but does so bypassing the standard model of the central dogma of molecular biology. Transcription and translation apparently do not play a role in this replication process.
This theory is a major departure from previously established biological dogma. A scientist decides to test the protein-only theory of prion propagation. He establishes his experiment as follows:
Homogenized brain matter of infected rabbits is injected into the brains of healthy rabbits, as per the following table:
Rabbit 1 and 2: injected with normal saline on days 1 and 2
The above trials serve as controls.
Rabbit 3 and 4: injected with homogenized brain matter on days 1 and 2
The above trials use unmodified brain matter.
Rabbit 5 and 6: injected with irradiated homogenized brain matter on days 1 and 2
The above trials use brain matter that has been irradiated to destroy nucleic acids in the homogenate.
Rabbit 7 and 8: injected with protein-free centrifuged homogenized brain matter on days 1 and 2
The above trials use brain matter that has been centrifuged to generate a protein-free homogenate and a protein-rich homogenate based on molecular weight.
Rabbit 9 and 10: injected with boiled homogenized brain matter on days 1 and 2
The above trials use brain matter that have been boiled to destroy any bacterial contaminants in the homogenate.
A scientist shows that PrPC in normal nervous cells helps speed nervous transmission. What other structures help speed nervous transmission?
Schwann cells act as insulators on nervous tissue to help propagate nervous transmission via saltatory conduction. This speeds transmission and makes axonal signal propagation much more rapid.
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Which of the following structures creates a myelin sheath for axons in the central nervous system?
Oligodendrocytes and Schwann cells both create myelin sheaths for axons, however, oligodendrocytes function in the central nervous system and Schwann cells function in the peripheral nervous system.
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