Hypothalamus & Autonomic System Study Packet

Which of these physiological changes would not be considered part of the sympathetic “fight-or-flight” response?

Increased stomach motility — sympathetic activation typically reduces digestion to redirect resources.

Which type of fiber could be considered the longest in the autonomic system?

Preganglionic parasympathetic fiber — they travel long distances before synapsing in terminal ganglia.

Which signalling molecule is most likely responsible for an increase in digestive activity?

Acetylcholine — parasympathetic outflow uses ACh to stimulate digestion.

Which of these cranial nerves contains preganglionic parasympathetic fibers?

Facial nerve (CN VII) — carries fibers to lacrimal, nasal, submandibular, and sublingual glands.

Which of the following is not a target of a sympathetic preganglionic fiber?

Intramural ganglion — these belong to the parasympathetic division.

Which of the following represents a sensory input that is not part of both the somatic and autonomic systems?

Vision — it’s primarily a special somatic sense.

What is the term for a reflex that does not include a CNS component?

Short reflex — occurs locally, such as in the enteric nervous system.

What neurotransmitter will result in constriction of the pupil (miosis)?

Acetylcholine — acts via parasympathetic activation of the iris sphincter.

What gland produces a secretion that causes “fight-or-flight” responses?

Adrenal medulla — releases epinephrine and norepinephrine system-wide.

Which of these pairings is incorrect: norepinephrine dilates pupils, epinephrine increases BP, ACh decreases digestion, norepinephrine increases HR?

Acetylcholine decreases digestion — incorrect; ACh increases digestion via parasympathetic activation.

Which forebrain structure is the master control center for homeostasis through autonomic and endocrine systems?

Hypothalamus — integrates endocrine, autonomic, and behavioral responses.

Which nerve projects to the hypothalamus to indicate light level?

Optic nerve (CN II) — via the retinohypothalamic tract to the suprachiasmatic nucleus.

What limbic lobe region triggers stress responses via the hypothalamus?

Amygdala — links emotion to autonomic and endocrine output.

What are preganglionic sympathetic fibers to the heart called?

Cardiac accelerator nerves — increase heart rate and contractility.

What tract connects forebrain and brain-stem structures with the hypothalamus?

Medial forebrain bundle — major limbic-hypothalamic pathway.

A drug affecting both divisions of the autonomic system binds to which receptor?

Nicotinic receptor — found at all autonomic ganglia.

A drug is called an agonist if it .

Acts like the natural neurotransmitter by binding to its receptor.

Which drug would counter atropine poisoning?

Muscarinic agonist — restores parasympathetic function blocked by atropine.

Which type of drug could reduce anxiety symptoms?

Alpha-adrenergic blocker — dampens sympathetic effects like tremor and hypertension.

Which drug type can treat asthma by opening airways?

Sympathomimetic — activates β₂-adrenergic receptors to dilate bronchi.

The hypothalamus is considered the autonomic control center of the body.

True — it regulates hormones, temperature, hunger, thirst, and circadian rhythm.

The majority of all afferent pathways synapse in the hypothalamus.

False — many do, but most sensory pathways project elsewhere.

Which of the following is not a visible boundary of the hypothalamus?

Internal capsule — it’s lateral and not externally visible.

The hypothalamic sulcus is the rostral continuation of what brainstem feature?

Sulcus limitans — marks the sensory-motor divide from brainstem into diencephalon.

How does cortisol regulate its own levels in the body?

By inhibiting release of corticotropin-releasing hormone (CRH) from the hypothalamus — negative feedback loop.

Which neurotransmitter is most implicated in mood and emotional behavior?

Serotonin — regulates mood; dopamine is more tied to reward and movement.

What is a key difference between the sympathetic and parasympathetic systems?

Sympathetic prepares for fight-or-flight; parasympathetic promotes rest-and-digest.

What is the primary function of vasopressin (ADH)?

Regulating blood volume and osmolarity — conserves water via kidney action.

Which best describes the role of the locus coeruleus?

Releases norepinephrine — promotes arousal and attention.

What is the main function of the suprachiasmatic nucleus (SCN)?

Synchronizing circadian rhythms with the light-dark cycle.

How does the hypothalamus communicate with the anterior pituitary?

By secreting hypophysiotropic hormones into portal blood — regulates pituitary output.

Which of these is not part of the nervous system operating in expanded space/time?

Corticospinal tract — it’s a direct, fast motor pathway.

What is the function of diffuse modulatory systems?

Regulate broad behavioral states such as mood, arousal, and motivation.

How does the CNS innervate smooth vs. skeletal muscle?

Through pre- and post-ganglionic chains for smooth; direct somatic neurons for skeletal.

Which hypothalamic nucleus regulates spinal autonomic output?

Paraventricular nucleus — controls sympathetic and parasympathetic signals.

A man suddenly falls asleep and loses muscle tone. What neurotransmitter is affected?

Orexin — deficiency causes narcolepsy with cataplexy.

Why do some antihistamines cause drowsiness?

They block central histamine that normally promotes wakefulness.

How is viscerosensory information relayed to the hypothalamus?

Via solitary and parabrachial nuclei — transmit BP and fluid balance data.

A stroke causes vertigo, hoarseness, and Horner’s signs; which artery is blocked?

Posterior inferior cerebellar artery (PICA) — lateral medullary syndrome.

A patient shows Horner’s signs; which site is NOT involved?

Medial pons — does not produce Horner’s syndrome when damaged.

A pituitary tumor most likely compresses what structure?

Optic chiasm — lies just above the pituitary gland.

Parvocellular is to magnocellular neurosecretory system as:

Anterior pituitary is to posterior pituitary — different hormone targets.

What does the median eminence contain?

Neurovascular contacts of parvocellular neurons — interface for releasing hormones.

Which structure is part of the telencephalon?

Cerebral cortex — derived from embryonic telencephalon.

Which division of the brain contains pons and cerebellum?

Metencephalon — includes both structures.

“Myelencephalon” refers to which adult structure?

Medulla — Greek for marrow; Latin “medulla” also means marrow.

What do we call a mass of neurons with an unclear boundary?

A locus — a small, poorly defined cluster of neuron cell bodies.

What is a locus?

A small, well-defined group of neuron cell bodies — example: locus coeruleus.

What is a lemniscus?

A ribbon-like bundle of CNS axons — such as the medial lemniscus.

What is a bundle?

A collection of CNS axons that don’t all start or end in the same place.

What is the largest commissure in the human brain?

Corpus callosum — connects left and right hemispheres.

What is the minimum number of layers a cortex can have?

Three — all cortices have at least three layers; neocortex has six.

All cortices have a layer.

Molecular layer — outermost layer composed mainly of dendrites and axons.

Where is the substantia nigra located?

In the tegmentum — midbrain region for movement control.

Which temporal-lobe structure is essentially folded cortex?

Hippocampus — allocortex involved in memory.

What does the reticular formation do?

Regulates sleep and arousal levels — integrates sensory and motor signals.

Which is more posterior, the amygdala or the hippocampus?

Hippocampus — lies farther posterior in the temporal lobe.

Which structure includes the inferior and superior colliculi?

Tectum — dorsal midbrain visual and auditory reflex center.

Which cerebral artery runs next to the corpus callosum?

Pericallosal branch of the anterior cerebral artery — follows the callosal surface.

What do we call an area outside the brain where CSF pools?

Cistern — an enlarged subarachnoid space.

Which space connects the third and fourth ventricles?

Cerebral aqueduct — narrow midbrain channel for CSF flow.

What do arachnoid granulations do?

Allow CSF to drain into venous blood — maintain CSF balance.

Which artery supplies the primary auditory cortex?

Middle cerebral artery — serves superior temporal gyrus.

The anterior and middle cerebral arteries receive blood from which vessel?

Internal carotid artery — divides into those branches.

Loss of sensation and movement in the left leg indicates blockage of which artery?

Right anterior cerebral artery — supplies medial motor/sensory cortex for the leg.

Blurred vision and hallucinations suggest blockage of which artery?

Posterior cerebral artery — supplies primary visual cortex.

Which structure forms the lateral walls of the third ventricle?

Thalamus — its medial surfaces bound the ventricle.

Is the tectum on the dorsal or ventral surface of the brainstem?

Dorsal — “tectum” means roof.

Why aren’t olfactory tracts considered cranial nerve I?

Olfactory receptors form the nerve; tracts are secondary CNS projections.

Which nerve moves the eyes downward and toward the nose?

Trochlear nerve (CN IV) — innervates the superior oblique muscle.

Which nerve closes the eyelid?

Facial nerve (CN VII) — activates orbicularis oculi muscle.

A pregnant woman with right-sided facial droop and inability to close right eye likely has what?

Bell’s palsy — right facial nerve damage.

How do pain/temperature fibers travel in the trigeminal system?

Descend to spinal trigeminal nucleus → contralateral spinothalamic tract.

Which pathway connects brainstem nuclei controlling eye movement?

Medial longitudinal fasciculus — coordinates conjugate gaze.

Which trigeminal nucleus is more medial, sensory or motor?

Motor nucleus — motor nuclei lie medially in the brainstem.

Which cranial nerves mediate the corneal blink reflex?

Trigeminal (V) afferent and Facial (VII) efferent — trigeminal senses, facial closes eyes.

What disorder results from facial-nerve damage?

Bell’s palsy — causes unilateral facial paralysis.

Which cranial nerve provides parasympathetic output to thorax and abdomen?

Vagus nerve (CN X) — principal parasympathetic supply.

Which cranial nerves carry taste information?

Facial (VII), Glossopharyngeal (IX), and Vagus (X) — convey taste from tongue & epiglottis.

Touching the right cornea makes only the left eye blink; which nerve is damaged?

Right facial nerve — efferent limb fails to close right eye.

Sticking out the tongue shifts it left; which nerve controls the movement?

Hypoglossal nerve (CN XII) — motor to tongue muscles.

When the tongue deviates left, which side is damaged?

Left side — tongue points toward the side of the lesion due to unopposed opposite genioglossus.