All Questions: 181-210

Correct answer: C

Cortisol is secreted from the adrenal glands, which are endocrine glands that sit on top of the kidneys. The release of cortisol causes a number of changes that help the body to deal with stress. For example, it helps to mobilize energy like glucose so the body has enough energy to cope with a prolonged stressor.

Correct answer: B

In CTE, tau proteins accumulate in neurons and other cells like astrocytes to form abnormal clusters or aggregates. The tau aggregates are called neurofibrillary tangles when they form in neurons and astrocytic or glial tangles when they form in astrocytes. These protein aggregates are a primary hallmark of CTE.

Correct answer: A

The hallmark tremor of Parkinson's disease is often referred to as a "resting tremor." This type of tremor is worse at rest (when not moving), and typically subsides when someone makes a voluntary movement (e.g., reaching for something).

Correct answer: D

The dorsal columns-medial lemniscus pathway carries conscious proprioception (and fine touch, vibration, etc.) to your cerebral cortex for conscious awareness. Other pathways like spinocerebellar tracts handle unconscious proprioception, feeding it to the cerebellum for coordination (not conscious perception).

Correct answer: A

Phantom limb is a condition in which someone who has lost a part of their body continues to experience phantom sensations coming from that body part. Phantom sensations are thought to be experienced by almost all amputees, and most suffer from some degree of phantom pain.

Correct answer: B

The mammillary bodies are small structures in the brain that have critical connections with other areas involved in processing and storing memories. When the mammillary bodies are damaged, such as in conditions like Wernicke-Korsakoff syndrome, individuals often experience severe amnesia, particularly the inability to create new long-term memories.

Correct answer: C

The longest axons in the human body are those of the sciatic nerve, which extends from the lower back down to the toes. This nerve is both the largest and longest in the body, with axons that can reach about 1 meter (~3.3 feet) in length (its actual length is dependent on the height of the individual). It plays a crucial role in controlling movement and sensation in the legs and feet.

Correct answer: C

Most of the cerebral cortex in humans is classified as neocortex, which is so named because it is thought to have appeared relatively recently in vertebrate evolution. Neurons in the neocortex are typically arranged in six layers, which are distinguished from one another by differences in cell type and cell density.

Correct answer: B

The oculomotor nerve controls four of the six extraocular muscles (muscles that control movement of the eye), but it also supplies the levator palpebrae superioris---the muscle that elevates the eyelid. Thus, damage to the oculomotor nerve often causes drooping of the eyelid (ptosis), as well as deviation of the eye to the side and several other symptoms.

Correct answer: B

While various cerebellar regions are involved with posture, the vermis controls the trunk and axial muscles, making it the cerebellar region most directly responsible for maintaining posture and balance during standing and slow movement.

Correct answer: A

Agonism occurs when a drug binds to a receptor and causes a biological response. Agonists that can generate a maximal response at a receptor are called full agonists. Partial agonists are only able to generate a fraction of the possible response at a receptor.

Correct answer: B

The medulla oblongata, or the medulla, is the lowest part of the brainstem, found below the pons and above the spinal cord. There is no clear separation between the medulla and the spinal cord; instead the spinal cord gradually transitions into the medulla.

Correct answer: D

The corticospinal tract is the main pathway for voluntary movement.

Correct answer: D

The hypoglossal nerve is a motor nerve that controls all of the muscles of the tongue (except for one, the palatoglossus, which is controlled by the vagus nerve). Healthy function of the hypoglossal nerve is thus critical for things like eating, swallowing, and speaking.

Correct answer: A

The headache phase of a migraine is thought to be attributable to activation of the trigeminal nerve, a cranial nerve that acts as the main sensory nerve for the head. The trigeminal nerve supplies a variety of pain-sensitive structures, which might explain the characteristic head and eye pain of migraine. Activation of the trigeminal nerve also prompts the release of neurotransmitters that can dilate cranial blood vessels and further stimulate and sensitize pain receptors.

Correct answer: B

Although GABA is widely known as the brain's main inhibitory neurotransmitter, in early embryonic and neonatal development, GABA is primarily excitatory. GABA is excitatory early on because immature neurons contain a high concentration of chloride ions inside the cell. When GABA binds to its receptors, chloride flows out of the neuron, causing the cell to depolarize—making it more likely to fire. Mature neurons have lower levels of internal chloride and GABA is inhibitory.

Correct answer: B

The filum terminale is a thin structure that extends from the caudal end end of the spinal cord to the coccyx (tailbone). It serves to anchor the spinal cord within the vertebral canal.

Correct answer: A

The most common type of synapse in the central nervous system is an axodendritic synapse. In this type of synapse, the axon of one neuron forms a connection with the dendrite of another neuron. The other answer choices do occur, but are not as common as axodendritic synapses.

Correct answer: D

The middle cerebral arteries supply most of the lateral surface of the cerebral hemispheres, including parts of the frontal, temporal, and parietal lobes. They're especially important for areas involved in language, motor, and sensory functions.

Correct answer: C

Multipolar neurons are the most common type of neuron in the human nervous system and the nervous systems of other vertebrates. They usually have a single axon and many dendrites.

Correct answer: B

An EEG records voltage fluctuations from large groups of neurons, particularly when their activity is synchronized, mainly in the cerebral cortex. It does not have the spatial resolution to detect activity from single neurons; it reflects the summed electrical activity of many neurons.

Correct answer: C

The corneal reflex involves sensory input from the ophthalmic branch of the trigeminal nerve (CN V) and motor output via the facial nerve (CN VII), which causes blinking. Since the left eye blinks, the sensory portion (left CN V) is functioning properly. The failure of the right eye to blink suggests that the right facial nerve (CN VII) is not carrying out the motor response.

Correct answer: B

Olfactory receptors are located in the olfactory epithelium—a specialized area of tissue at the top of the nasal cavity. This is where odorant molecules first bind, initiating the sense of smell.

Correct answer: B

Microglia are the resident immune cells of the central nervous system (CNS). They constantly monitor the brain and spinal cord for signs of injury or infection and respond by engulfing pathogens, dead cells, and debris in a process called phagocytosis. This immune function helps maintain a healthy environment for neurons and supports recovery after injury.

Correct answer: A

The soma, also known as the cell body, is the central part of a neuron that contains the nucleus, along with other organelles like the endoplasmic reticulum and mitochondria. It plays a vital role in integrating incoming signals from the dendrites and generating outgoing signals to the axon. The nucleus inside the soma contains the cell's DNA and directs cellular activity.

Correct answer: D

During REM (rapid eye movement) sleep, the brain sends signals that actively inhibit motor neurons, causing a temporary paralysis of most voluntary muscles. This muscle atonia prevents us from physically acting out our dreams, which are most vivid and frequent during REM.

Correct answer: C

The resting membrane potential of a typical neuron is about -70 millivolts (mV), meaning the inside of the neuron is negatively charged relative to the outside. The negative resting potential is essential for the neuron’s ability to generate action potentials when stimulated.

Correct answer: C

The enteric nervous system is a specialized branch of the autonomic nervous system that governs the function of the gastrointestinal (GI) tract. It regulates digestion, including motility, secretion, and blood flow within the GI system—largely independent of the brain and spinal cord.

Correct answer: B

The arachnoid trabeculae are thin, web-like strands of connective tissue that extend from the arachnoid mater to the pia mater, spanning the subarachnoid space. They help suspend the brain and spinal cord in cerebrospinal fluid and contribute to the structural integrity of the meninges.

Correct answer: D

The basal ganglia are deeply involved in motor control and inhibition, and dysfunction in these circuits is strongly associated with Tourette syndrome and other tic disorders.