Random
At resting membrane potential, what is true?
A. Voltage-gated Na channels are open
B. Voltage-gated K channels are open
C. Leaky K channels are open
D. Na concentration is higher inside the cell
C. Leaky K channels are open
At rest, the membrane is more permeable to K than Na. K diffuses out of the cell down its concentration gradient, which leaves the inside of the cell MORE NEGATIVE than the outside.
Which of the following correctly describes mechanisms that protect the CNS?
I. Meninges provided layered connective tissue protection
II. CSF cushions brain and contributes to buoyancy
III. The blood-brain barrier allows free passage of all plasma proteins
IV. The skull and vertebral column provide rigid structural protection
I, II, and IV
I. Meninges provided layered connective tissue protection
II. CSF cushions brain and contributes to buoyancy
IV. The skull and vertebral column provide rigid structural protection
Note: The blood-brain barrier is highly selective and restricts most plasma proteins!
Which of the following correctly describes the efferent division of the peripheral nervous system? (select all that apply)
I. The somatic nervous system controls skeletal muscle.
II. The autonomic nervous system controls cardiac and smooth muscle.
III. The autonomic nervous system includes sympathetic and parasympathetic divisions.
IV. The somatic nervous system uses a two-neuron chain.
I, II, and III
I. The somatic nervous system controls skeletal muscle.
II. The autonomic nervous system controls cardiac and smooth muscle.
III. The autonomic nervous system includes sympathetic and parasympathetic divisions.
Note: Somatic motor pathway uses ONE neuron, NOT two!
Somatic = one neuron
Autonomic = two neurons (preganglionic and postganglionic)
Sensory transduction is best defined as:
A. The propagation of an action potential along an afferent neuron
B. The conversion of a stimulus energy into a graded receptor potential
C. The interpretation of sensory input in the cerebral cortex
D. The release of neurotransmitter from a sensory neuron
B. The conversion of a stimulus energy into a graded receptor potential
Receptor potentials are graded, not all-or-none like action potentials
Which hormone would MOST LIKELY bind to an intracellular receptor?
A. Epinephrine
B. Insulin
C. Thyroid hormone
D. Growth hormone
C. Thyroid Hormone
T3 and T4 are lipid-soluble, meaning they can cross the cell membrane and bind intracellularly. Epinephrine, insulin, and GH are water-soluble, so they cannot diffuse and must bind to a membrane receptor.
During prolonged physiological stress, cortisol secretion increases primarily due to activation of:
A. The sympathetic chain ganglia
B. The HPA axis
C. Direct stimulation from insulin
D. Increased calcitonin release
B. The HPA axis
Hypothalamus (CRH) > anterior pituitary (ACTH) > adrenal cortex (cortisol)
Cortisol increases blood glucose, promotes protein breakdown, and supports vascular responsiveness.
Which best describes the organization of primary motor and sensory cortices?
A. The primary motor cortex is located in the postcentral gyrus
B. The primary somatosensory cortex is located in the precentral gyrus
C. Both cortices are somatotopically organized
D. The motor cortex receives ascending sensory tracts directly from the spinal cord
C. Both cortices are somatotopically organized
The primary motor cortex is in the precentral gyrus (frontal lobe) and the primary somatosensory cortex is in the postcentral gyrus (parietal lobe). Both are arranged in a motor and sensory homunculus. Sensory information ascends to the thalamus first, NOT directly to motor cortex.
Which statement best describes autonomic motor neuron organization?
A. Preganglionic neurons originate in the ganglia and synapse in the CNS.
B. Postganglionic neurons release acetylcholine in both divisions.
C. Preganglionic neurons release acetylcholine onto nicotinic receptors in ganglia.
D. Autonomic motor neurons directly innervate skeletal muscle.
C. Preganglionic neurons release acetylcholine onto nicotinic receptors in ganglia.
Preganglionic neurons originate in the CNS. They release ACh > nicotinic receptors in autonomic ganglia. Postganglionic neurons differ:
-SANS: usually NE or norepinephrine
-PANS: ACh (muscarinic)
Which statement correctly compares phasic and tonic receptors?
A. Phasic receptors adapt slowly and signal stimulus duration.
B. Tonic receptors adapt rapidly and signal stimulus onset only.
C. Phasic receptors adapt rapidly and detect changes in stimulus intensity.
D. Tonic receptors stop firing when a stimulus persists.
C. Phasic receptors adapt rapidly and detect changes in stimulus intensity.
Phasic = adapts quickly to detect change, on/off (ex. clothes on skin)
Tonic = slowly adapts and detects signal duration and intensity (ex. pain)
Cortisol increases the number of epinephrine receptors on vascular smooth muscle. This is an example of:
A. Synergistic interaction
B. Permissive interaction
C. Antagonistic interaction
D. Tropic interaction
B. Permissive interaction
One hormone enhances the effect of another by increasing receptor availability or responsiveness. Cortisol alone doesn't cause vasoconstriction... but permits epinephrine to act fully!
What are the characteristics of an action potential? (select all that apply)
A. All-or-none
B. Decremental
C. Requires threshold
D. Same amplitude regardless of stimulus strength
E. Encodes intensity by frequency
A. All-or-none
C. Requires threshold
D. Same amplitude regardless of stimulus strength
E. Encodes intensity by frequency
*Graded potentials are decremental, not action potentials!
A patient has fluent but nonsensical speech and cannot comprehend spoken language. The lesion is most likely where?
Wernicke's area in the temporal lobe!
Broca's aphasia is nonfluent, effortful speech, but intact comprehension (frontal lobe)
Which of the following statements are correct? (select all that apply)
I. Sympathetic ganglia are located near the spinal cord.
II. Sympathetic preganglionic neurons are short.
III. The adrenal medulla functions as a modified sympathetic ganglion.
I, II, and III!
I. Sympathetic ganglia are located near the spinal cord.
II. Sympathetic preganglionic neurons are short.
III. The adrenal medulla functions as a modified sympathetic ganglion.
Which statement correctly describes pitch and loudness?
A. Pitch depends on amplitude; loudness depends on frequency.
B. Pitch depends on frequency; loudness depends on amplitude.
C. Both pitch and loudness depend only on the width of the basilar membrane.
D. Hertz measures amplitude.
B. Pitch depends on frequency; loudness depends on amplitude.
Pitch = frequency in Hz
Loudness = amplitude, or wave height
Higher frequency > basilar membrane vibrates near base (narrow, stiff)
Lower frequency > larger membrane displacement at the apex (wide, flexible)
Which hormone is synthesized in the hypothalamus and released from the posterior pituitary?
A. Growth hormone
B. TSH
C. Oxytocin
D. ACTH
C. Oxytocin
Posterior Pituitary Hormones: ADH (vasopressin), Oxytocin
^made in hypothalamus, transported down axons, and released from posterior pituitary
Anterior Pituitary Hormones: FLAT PiG
^synthesized in anterior pituitary gland itself
What prevents an action potential from traveling backward down the axon?
A. K channels close permanently
B. Absolute refractory period due to Na channel inactivation
C. Myelin blocks backward movement
D. Na/K pump prevents reversal
B. Absolute refractory period due to Na channel inactivation
Which of the following statements are correct?
I. The thalamus functions as a major sensory relay station
II. The hypothalamus regulates endocrine function via the pituitary gland
III. The medulla oblongata contains vital autonomic centers
IV. The cerebellum initiates voluntary motor movement
I, II, and III
I. The thalamus functions as a major sensory relay station
II. The hypothalamus regulates endocrine function via the pituitary gland
III. The medulla oblongata contains vital autonomic centers
Note: The cerebellum coordinates movement, NOT initiates
Which of the following correctly describes parasympathetic regulation? (select all that apply)
I. Parasympathetic postganglionic neurons release acetylcholine.
II. Muscarinic receptors are located on target organs.
III. Atropine enhances parasympathetic activity.
IV. Parasympathetic ganglia are located near or within target organs.
I, II, and IV
I. Parasympathetic postganglionic neurons release acetylcholine.
II. Muscarinic receptors are located on target organs.
IV. Parasympathetic ganglia are located near or within target organs.
Note: Atropine is a muscarinic antagonist which blocks parasympathetic effects. Atropine increases HR, decreases secretions, and allows bronchodilation.
Which statement is correct regarding rods and cones?
A. Rods provide high visual acuity and color vision.
B. Cones are most abundant in the peripheral retina.
C. The fovea centralis contains a high density of cones.
D. Rods function best in bright light conditions.
C. The fovea centralis contains a high density of cones.
Rods = high sensitivity, low acuity, night vision
Cones = color vision, high acuity, bright light
Fovea centralis = densely packed cones leading to sharp central vision!
Which statement correctly distinguishes gigantism from acromegaly?
A. Gigantism occurs after epiphyseal closure
B. Acromegaly affects children only
C. Acromegaly results from GH deficiency
D. Gigantism results from excess GH before epiphyseal closure
D. Gigantism results from excess GH before epiphyseal closure
Gigantism = excess GH before plates close > increased height
Acromegaly = excess GH after closure > enlarged hands, feet, jaw
Organize the correct order of events during an action potential
I. Voltage-gated Na channels inactivate
II. Threshold is reached
III. Voltage-gated K channels open
IV. Na rapidly enters the cell
II > IV > I > II
II. Threshold is reached >
IV. Na rapidly enters the cell >
I. Voltage-gated Na channels inactivate >
II. Voltage-gated K channels open
Which sequence correctly represents the pathway of a withdrawal reflex?
A. Motor neuron → interneuron → sensory receptor → spinal cord
B. Sensory receptor → afferent neuron → interneuron → efferent neuron
C. Efferent neuron → spinal cord → receptor → interneuron
D. Sensory receptor → efferent neuron → brainstem → muscle
B. Sensory receptor → afferent neuron → interneuron → efferent neuron
Withdrawal reflex pathway:
Nociceptor (receptor) activated
Afferent (sensory) neuron enters the dorsal root
Synapse in the spinal cord (interneuron)
Efferent (motor) neuron exits the ventral root
Effector muscle contracts!!!
Stimulation of β1 receptors would most likely result in:
A. Bronchoconstriction
B. Decreased heart rate
C. Increased heart rate and contractility
D. Increased GI motility
C. Increased heart rate and contractility
β1 → Heart → ↑ HR + ↑ contractility
β2 → bronchodilate
α1 → vasoconstrict
Accommodation for near vision involves:
A. Relaxation of the ciliary muscle and lens flattening
B. Contraction of the ciliary muscle and lens thickening
C. Decreased lens curvature
D. Increased pupil dilation only
B. Contraction of the ciliary muscle and lens thickening
Near object > ciliary muscles contract > fibers relax > lens thickens
Thick lens = greater refractive power
What is the primary stimulus for insulin release?
A. Decreased blood glucose
B. Increased blood glucose
C. Increased amino acids only
D. Sympathetic nervous system activation
B. Increased blood glucose
Increased blood glucose activates B cells in pancreas to release insulin. Insulin promotes glucose uptake, glycogenesis, and lipogenesis. Amino acids can stimulate insulin, but glucose is primary!