Tissue & Brain
These specialized star-shaped glial cells support neurons, form the blood-brain barrier, and regulate the chemical environment.
Answer: What are astrocytes?
The central nervous system consists exclusively of these two major structural components.
Answer: What are the brain and spinal cord?
Often called the "rest and digest" division, this branch of the ANS conserves energy and slows down the heart rate.
Answer: What is the parasympathetic nervous system?
These specific photoreceptor cells in the retina are highly sensitive to light and allow us to see in dim conditions, though only in grayscale.
Answer: What are rods?
Known as the "master gland," this small structure at the base of the brain secretes hormones that control several other endocrine glands.
Answer: What is the pituitary gland?
This gaps-filled insulating layer wraps around axons to drastically speed up the transmission of electrical impulses.
Answer: What is the myelin sheath?
This is the total number of pairs of cranial nerves that emerge directly from the brain and brainstem.
Answer: What is 12?
Activation of this branch of the ANS causes pupils to dilate, airways to relax, and heart rate to spike.
Answer: What is the sympathetic nervous system?
Sound waves bounce off the tympanic membrane, vibrating these three tiny middle ear bones collectively known as auditory ossicles.
Answer: What are the malleus, incus, and stapes? (Also accept: hammer, anvil, and stirrup)
This crucial brain region links the nervous system to the endocrine system by controlling the pituitary gland via hormonal and neural signals.
Answer: What is the hypothalamus?
Located at the posterior base of the brain, this structure coordinates voluntary movements, balance, and posture.
Answer: What is the cerebellum?
This butterfly-shaped region inside the spinal cord consists primarily of neuronal cell bodies and unmyelinated axons.
Answer: What is gray matter?
This is the primary neurotransmitter released by all preganglionic neurons in both the sympathetic and parasympathetic pathways.
Answer: What is acetylcholine (ACh)?
Olfactory receptors pass their axon filaments upward through the tiny perforations of this bone plate to reach the brain.
Answer: What is the cribriform plate?
Beta cells located within the pancreatic islets secrete this vital hormone to lower blood glucose levels.
Answer: What is insulin?
This deep groove separates the left and right cerebral hemispheres.
Answer: What is the longitudinal fissure?
Sensory information enters the spinal cord through this specific root structure on the posterior side.
Answer: What is the dorsal root?
Unlike the somatic nervous system, the autonomic system utilizes a chain of this many motor neurons to reach its effector organs.
Answer: What is two?
These specialized mechanoreceptors embedded deep in the dermis are highly sensitive to deep pressure and high-frequency vibrations.
Answer: What are Pacinian corpuscles? (Also accept: lamellar corpuscles)
This hormone, synthesized by the pineal gland, regulates sleep-wake cycles and responds directly to lighting conditions.
Answer: What is melatonin?
This specific lobe of the cerebral cortex houses the primary auditory cortex and is heavily involved in memory processing.
Answer: What is the temporal lobe?
This collection of spinal nerves extends downward past the end of the spinal cord, resembling a horse's tail.
Answer: What is the cauda equina?
Sympathetic preganglionic fibers bypass the sympathetic chain to terminate directly on this endocrine structure, releasing epinephrine into the blood.
Answer: What is the adrenal medulla?
This fluid-filled structure in the inner ear houses the organ of Corti, which converts mechanical sound vibrations into electrical nerve impulses.
Answer: What is the cochlea?
Unlike hydrophilic amino acid derivatives, this class of lipid-soluble hormones can diffuse directly across target cell membranes to bind to intracellular receptors.
Answer: What are steroid hormones?