The _________ and _________ nervous systems are responsible for regulating the physiology and behavior of the individual in response to the environment.
Hint: These two systems are the two largest divisions of the nervous system.
The central and peripheral nervous systems are responsible for regulating the physiology and behavior of the individual in response to the environment.
These systems are often abbreviated CNS and PNS, respectively.
These two structures are the location of all nerves contained within the central nervous system.
The brain and the spinal cord
This division of the nervous system includes all nerves outside the brain/spinal cord.
The peripheral nervous system
The peripheral nervous system is generally divided into what two subsystems?
Hint: These divisions are delineated based on whether or not they require conscious input.
The somatic and autonomic nervous systems
The somatic nervous system governs conscious movement, such as the movement of skeletal muscle. The autonomic nervous system controls unconscious, or automatic, functions such as heart rate and peristalsis.
Note that breathing is a rare example of a function that is under both voluntary and involuntary control to some extent.
Vasodilation is controlled by the [autonomic/somatic] nervous system, which is a subdivision of the [central/peripheral] nervous system.
Choose one term from each box above to accurately complete the sentence.
Vasodilation is controlled by the autonomic nervous system, which is a subdivision of the peripheral nervous system.
Since vasodilation is performed unconsciously, it is governed by the autonomic nervous system. Both the autonomic and the somatic nervous systems are subdivisions of the peripheral nervous system (PNS).
Contraction of the biceps muscle when lifting weights is controlled by the [autonomic/somatic] nervous system, which is a subdivision of the [central/peripheral] nervous system.
Choose one term from each box above to accurately complete the sentence.
Contraction of the biceps muscle when lifting weights is controlled by the somatic nervous system, which is a subdivision of the peripheral nervous system.
This statement describes a conscious function, so it is governed by the somatic nervous system. Both the autonomic and the somatic nervous systems are subdivisions of the peripheral nervous system (PNS).
The official name for the “fight-or-flight” division of the nervous system is the:
sympathetic nervous system.
The sympathetic nervous system is activated when the individual is stressed or in acute danger. Epinephrine is released to cause an increase in heart rate, respiratory rate, and blood flow to muscles to escape or fight off the threat.
The official name for the “rest-and-digest” division of the nervous system is the:
parasympathetic nervous system.
This branch of the nervous system is active when the individual is not in danger (that is, when he or she is resting, eating, or otherwise in a relaxed state). Heart rate and breathing rate are slowed, and blood flow is diverted to the digestive system.
Peristalsis is inhibited when which branch of the autonomic nervous system is activated?
The sympathetic nervous system
Inhibition of peristalsis (and of digestive activity in general) is characteristic of the sympathetic, or fight-or-flight, nervous system.
Increased secretion of saliva is associated with the activation of which branch of the autonomic nervous system?
The parasympathetic nervous system
An easy way to remember this is to note that the parasympathetic (or rest-and-digest) system is generally associated with digestion and related functions (which include salivation).
An increase in blood glucose level is associated with activation of which branch of the autonomic nervous system?
The sympathetic nervous system
Sympathetic activation results in the release of epinephrine, which increases blood glucose level by stimulating the breakdown of glycogen and subsequent release of glucose from the liver.
Dilated pupils are a sign that which branch of the autonomic nervous system is activated?
The sympathetic nervous system
Pupil dilation is a result of sympathetic (fight-or-flight) activation. You can remember this by imagining the pupils letting in a larger amount of light to better visualize a threat.
Activation of which branch of the autonomic nervous system is associated with decreased blood flow to skeletal muscles?
The parasympathetic nervous system
Overall, parasympathetic activation results in decreased blood flow to muscles and increased blood flow to the digestive system.
What neurological circuit is shown in the image below?
A reflex arc
Reflex arcs are nerve pathways involved in a reflex action. At its simplest, a reflex arc is just a sensory neuron, a synapse, and a motor neuron.
The image shows a person touching a hot surface. The neurons contained within the reflex arc will immediately react, causing him to withdraw his hand.
Importantly, reflex arcs typically synapse in the spinal cord, meaning that they avoid involvement of the:
brain.
Reflex arcs typically do not require input from the brain. It is crucial that reflexes occur quickly; sending information to and from the brain would be too time-consuming.
Name the three types of nerve cells (neurons) in the human nervous system.
Motor neurons, sensory neurons, and interneurons
Describe the general function of sensory neurons.
Sensory neurons transmit sensory information (both external and internal) from the periphery of the body to the central nervous system.
Describe the general function of motor neurons.
Motor neurons transmit signals from the central nervous system to the periphery of the body (specifically, to targets such as muscles and glands).
Motor neurons provide the neural impulses that tell our muscles to contract, allowing movement.
Name the type of neuron that is commonly found between a sensory neuron and a motor neuron in a reflex arc.
An interneuron
Interneurons are the third type of neurons in the nervous system (with the other two being motor and sensory neurons). Interneurons are always located between other neurons.
A gap between neurons into which neurotransmitter molecules are released is termed a:
synapse.
Interestingly, neurons do not directly contact each other. Instead, they are separated by small gaps termed synapses.
How many neurons are involved in a monosynaptic reflex arc, and what type(s) of neurons are they?
Two neurons are involved in a monosynaptic reflex arc: a sensory neuron and a motor neuron.
“Monosynaptic” means “one synapse.” A synapse is a gap between neurons, so this reflex arc must involve two neurons.
How many neurons are involved in a disynaptic reflex arc, and what type(s) of neurons are they?
Three neurons are involved in a disynaptic reflex arc: a sensory neuron, a motor neuron, and an interneuron.
“Disynaptic” means “two synapses.” To have two synapses (gaps between neurons), this reflex arc must involve three neurons.
Due to the direction in which they transmit information (from the periphery toward the brain), sensory neurons are also termed ________ neurons.
Due to the direction in which they transmit information (from the periphery toward the brain), sensory neurons are also termed afferent neurons.
In general, “afferent” refers to movement or transmission toward a point of reference.
True or false:
A neuron that transmits impulses from the spinal cord toward skeletal muscle fibers is an afferent neuron.
False
This statement describes a motor neuron. Motor neurons transmit impulses away from the central nervous system (here, the spinal cord), and are thus termed efferent, not afferent, neurons.
Which molecules are responsible for communication between neurons and the propagation of nerve signals to the body?
Neurotransmitters
True or false:
GABA, serotonin, and epinephrine are inhibitory neurotransmitters.
False
This statement is false because epinephrine is not inhibitory. Excitatory neurotransmitters include acetylcholine and epinephrine, while inhibitory neurotransmitters include dopamine, GABA, and serotonin.
This neurotransmitter is strongly associated with feelings of euphoria and happiness and often contributes to addiction to recreational drugs.
Many antidepressants function by inhibiting the reuptake of this neurotransmitter.
Serotonin
While both serotonin and dopamine are associated with feelings of euphoria, only serotonin is a treatment target for depression via selective serotonin reuptake inhibitors.
________ neurons synthesize dopamine, while ________ receptors are stimulated by nicotine.
Dopaminergic neurons synthesize dopamine, while nicotinergic receptors are stimulated by nicotine.
Defective dopaminergic neurons can cause impaired motor movements, loss of feelings, changes in mood, and impaired memory.
List the seven primary neurotransmitters or neurotransmitter types used in the body.
- Gamma-aminobutyric acid (GABA)
- Acetylcholine
- Epinephrine
- Norepinephrine
- Serotonin
- Dopamine
- Endorphins
The main inhibitory neurotransmitter in the adult human brain is:
gamma-aminobutyric acid (GABA).
This neurotransmitter is involved in the reward pathway that is crucial to drug addiction.
As an additional hint, neurons that produce it deteriorate in patients with Parkinson’s disease.
Dopamine
Dopamine is the neurotransmitter most classically associated with pleasure. It plays an important role in drug addiction via the brain’s reward pathway. In patients with Parkinson’s disease, dopaminergic neurons in a brain region termed the substantia nigra degenerate.
This neurotransmitter is alternatively termed noradrenaline.
Norepinephrine
Norepinephrine has many of the same effects as epinephrine (adrenaline), such as increasing heart rate and increasing blood glucose level.
Also known as adrenaline, this medication (a neurotransmitter/hormone) is administered to stimulate heart rate and breathing in patients who suffer extreme allergic reactions.
Epinephrine
Epinephrine, like norepinephrine, stimulates heart rate and breathing rate and is generally associated with the activity of the sympathetic nervous system.
These neurotransmitters are responsible for the “runner’s high” that makes exercise so appealing to many athletes.
Endorphins
Endorphins (the name of which essentially comes from “endogenous morphines”) are pain-killing neurotransmitters released after injury or exercise.
This neurotransmitter is the target of a class of drugs known as SSRIs.
Serotonin
The abbreviation may have given this away! However, for the MCAT, you should also understand what SSRI stands for (selective serotonin reuptake inhibitor) and what such medications do (increase the concentration of serotonin available in the synapses).
This neurotransmitter has a number of functions. It serves as both the main parasympathetic neurotransmitter and the neurotransmitter that stimulates muscle contraction at the neuromuscular junction.
Acetylcholine
These functions may seem opposite (since we don’t typically think of lots of muscle contraction happening when the parasympathetic nervous system is activated), so it can be helpful to think of them as two entirely separate things, both of which acetylcholine controls.
A person with severe problems balancing, standing upright, and exercising hand-eye coordination is likely to have a damaged:
cerebellum.
The cerebellum, located at the very rear of the brain, is the region most closely associated with balance, posture, and coordination.
Name the most evolutionarily ancient part of the brain, which is continuous with the spinal cord.
The brain stem
In keeping with its ancient evolutionary history, the brain stem is involved in extremely basic and vital functions, such as the control of breathing and heart rate.
Name the specific part of the brain stem that is situated above the pons and that regulates heart rate, blood pressure, and breathing.
The medulla oblongata
While sometimes mistaken as synonymous with the brain stem, the medulla oblongata (or simply “medulla”) is only part of that structure. Other parts of the brain stem include the pons and the midbrain.
Name the three regions of the brain, named for their relative positions.
The forebrain, the midbrain, and the hindbrain
Also known as the prosencephalon, this region of the brain contains the cerebrum, thalamus, limbic system, and hypothalamus.
The forebrain
The forebrain regulates abstract thinking, logic, and emotions.
The mesencephalon of the brain contains the tegmentum, tectum, and substantia nigra. It is also termed the:
midbrain.
The midbrain is responsible for dopamine production (habituation, motivation, and reward) and assists in visual and auditory processing.
The cerebellum, medulla, and pons are located in the:
hindbrain.
The hindbrain is in charge of motor control, respiratory reflexes, gastrointestinal reflexes, and sexual arousal.
Name the part of the forebrain that primarily fulfills homeostatic roles, such as the regulation of water balance and metabolism.
The hypothalamus
The hypothalamus plays these roles primarily through both the production and the stimulation of hormones.
The hypothalamus is connected to the anterior pituitary gland through which circulation-based structure?
The hypophyseal portal system
This system is a network of blood vessels that connects the hypothalamus with the anterior pituitary. It allows for the easy transport of hormones between these two structures.
Name the part of the forebrain that receives and directs most sensory information to its proper destination.
The thalamus
The thalamus serves as a kind of “connecting station,” receiving sensory information and relaying it to where it needs to go.
Name the part of the forebrain that is most closely involved with the regulation of sleep and wakefulness.
The pineal gland
The pineal gland produces melatonin, a hormone that regulates sleep/wake cycles.
This group of nuclei are located deep in the brain and play a role in the smoothness of voluntary muscle movements, among other functions.
The basal ganglia
Importantly, the basal ganglia (specifically, a substructure of the basal ganglia termed the substantia nigra) are destroyed in Parkinson’s disease, resulting in movement deficiencies.
The hippocampus, septal nuclei, nucleus accumbens, and amygdala are all parts of what larger set of brain structures?
The limbic system
For the MCAT, the most structure to be familiar with in the context of the limbic system is the amygdala, as it plays key roles in fear, aggression, and emotion.
Which limbic system structure is most closely involved with the formation and consolidation of memory?
The hippocampus
The hippocampus, which is considered part of the limbic system, is primarily involved in the consolidation of short-term memory into long-term memory.
How many lobes does the human brain contain?
Four lobes
Name all of the lobes of the human brain.
The human brain contains four lobes. They are:
- the frontal lobe
- the parietal lobe
- the temporal lobe
- and the occipital lobe.
Which lobe of the brain plays the greatest role in higher-level reasoning?
Hint: This lobe does not fully develop until the individual is approximately 25 years old.
The frontal lobe
The frontal lobe is closely involved in higher-level reasoning (problem-solving, judgment, etc.). Individuals in their teens or early twenties may tend to be relatively impulsive prior to the conclusion of frontal lobe development.
The part of the frontal lobe that controls executive function (such as planning, controlling impulses, remembering that one has something important to do, and so on) is the:
prefrontal cortex.
The lobe of the brain that mainly functions to facilitate vision is the ________ lobe.
The lobe of the brain that mainly functions to facilitate vision is the occipital lobe.
The occipital lobe, located at the rear of the brain above the cerebellum, is the location of the visual cortex.
The somatosensory cortex is found in which lobe of the brain?
The parietal lobe
Located at the top of the brain (behind the frontal lobe), the parietal lobe is the location of the somatosensory cortex, which is the region of the brain responsible for the processing of sensory information.
Hearing, emotion, and memory are all controlled at least in part by which brain lobe?
Hint: This lobe is the location of the auditory cortex.
The temporal lobe
Just as the occipital lobe is the location of the visual cortex, the temporal lobe is the location of the auditory cortex, meaning that when you see hearing mentioned, the temporal lobe should immediately come to mind.
True or false:
The left and right hemispheres share an equal burden of cortical function.
False
Lateralization refers to the fact that our brain divides specific functions across each hemisphere unevenly, with each hemisphere predominantly performing certain functions.
This hemisphere of the brain is the predominant driver of movement of the right side of the body. In most individuals, it is also associated with logic, language production, and analytic skills.
The left hemisphere
Brain control of many functions is contralateral, meaning that the left brain controls the right side of the body and vice versa. Additionally, in most individuals (specifically, left-brain-dominant individuals), the left side of the brain primarily functions in logic, analysis, and language.
This hemisphere of the brain is the predominant driver of movement of the left side of the body. In most individuals, it is also associated with spatial skills, recognition of emotions, and creativity.
The right hemisphere
Brain control of many functions is contralateral, meaning that the right brain controls the left side of the body and vice versa. Additionally, in most individuals, the right side of the brain primarily functions in spatial analysis, emotion recognition, and creativity/art/music.
True or false:
Functions related to the left side of the body that are controlled by the left hemisphere are under ipsilateral control.
True
“Ipsilateral” describes functions that are controlled by the same side of the brain, while “contralateral” refers to functions controlled by the opposite side. Most, albeit not all, functions in humans are under contralateral control.
This imaging technique makes use of computer-processed combinations of multiple X-ray measurements taken from multiple angles to produce cross-sectional images, or “slices,” of specific areas of the brain.
CT/CAT scan
These abbreviations stands for computed tomography and computerized axial tomography, respectively.
This imaging technique is used to observe metabolic processes and blood flow.
It functions via the detection of gamma rays emitted indirectly by a radionuclide (tracer), which is introduced into the body on a glucose analog, fludeoxyglucose.
Positron-emission tomography (PET)
This imaging technique attempts to quantify brain activity in a specific region by measuring changes in blood flow as it passes through tissue.
fMRI/functional magnetic resonance imaging
The most common form of fMRI is termed fMRI BOLD, where “BOLD” stands for “blood oxygen level-dependent.”
If a student from a large, high-crime city enters medical school in a low-crime rural area, adaptive trait theorists would expect the student’s level of anxiety walking down the street to _______ relative to their hometown, while _______ would expect their behavior to remain unchanged.
decrease, behavioral geneticists
Adaptive trait theorists would say that traits and behaviors are capable of changing in response to different environments. In contrast, behavioral geneticists focus on the relationship between behavioral traits and inherited genes. Geneticists would be more likely to believe that the student’s anxiety was genetic and unlikely to change.
This field of study involves the modification of gene expression without changing the overall genetic code.
Epigenetics
This allows the body to alter the phenotype without changing the genotype. Epigenetics are primarily influenced by environment.
The addition of _______ groups to DNA allows for gene silencing without directly affecting the genome itself.
The addition of methyl groups to DNA allows for gene silencing without directly affecting the genome itself.
This process is termed DNA methylation.
A species of rabbit lives in an area with large numbers of predators. Name a few traits that would be expected to evolutionarily predominate over time in this rabbit species.
Over time, the environment would favor cautious, sneaky, fast-running, and/or quiet rabbits.
Any traits that would increase the likelihood of a rabbit’s escape/evasion from predators would be evolutionarily favored.
Place the following human developmental stages in order:
- Conception
- Blastula
- Zygote
- Morula
- Embryo
- Fetus
- Newborn
Conception → zygote → morula → blastula → embryo → fetus → newborn
Name the reflex exemplified below.
If the sole of a 7-month-old’s foot touches the ground, the infant moves his or her legs in a walking motion.
Walking reflex
Name the reflex exemplified below.
If an object is placed against a baby’s palm, his or her fingers will close to grasp the object.
Palmar grasp reflex
Name the reflex exemplified below.
Her mother’s voice causes an infant to turn her head to the left, and simultaneously her left arm extends at the elbow while her right arm flexes at the elbow.
Tonic neck reflex
Name the reflex exemplified below.
Stroking an infant’s cheek causes the baby to turn towards the hand and open their mouth.
Rooting reflex
Name the reflex exemplified below.
If a bottle nipple touches the roof of an infant’s mouth, the infant will begin to suck.
Sucking reflex
Of the infant motor milestones below, which occurs first?
- Lift head while prone
- Crawl
- Walk with assistance
- Stand with assistance
- Roll over
- Stand unassisted
- Walk unassisted
- Sit unassisted
The first milestone is the infant lifting the head while prone.
For reference, the approximate age at which each milestone occurs is given below.
- 2 months: lift head while prone
- 3 months: roll over
- 6 months: sit unassisted
- 7 months: stand with assistance
- 9 months: crawl
- 10 months: walk with assistance
- 1 year: stand unassisted
- 13 months: walk unassisted
Of the infant motor milestones below, which occurs last?
- Lift head while prone
- Crawl
- Walk with assistance
- Stand with assistance
- Roll over
- Stand unassisted
- Walk unassisted
- Sit unassisted
The last milestone is the infant walking unassisted.
For reference, the approximate age at which each milestone occurs is given below.
- 2 months: lift head while prone
- 3 months: roll over
- 6 months: sit unassisted
- 7 months: stand with assistance
- 9 months: crawl
- 10 months: walk with assistance
- 1 year: stand unassisted
- 13 months: walk unassisted
During what age range do children learn fundamental movements?
Approximately 2-7 years old
During this time, the child begins to coordinate the limbs and can perform simple motor tasks, such as running, catching a ball, or jumping.
During which age range do children develop what is called “specialized movement”?
Approximately 7-14 years old
Children this age can use learned fundamental movements to complete specific actions (e.g. throwing a ball, riding a bike).
Name the standard female secondary sex characteristics that develop during puberty.
Females entering puberty experience:
- Growth of breasts
- Growth of pubic hair
- Growth of underarm hair
- Onset of menstruation
- Increased oil and sweat production
- Fat deposition in hips
Name the standard changes associated with the onset of male adolescence.
Males entering puberty experience:
- Growth of pubic, facial, and underarm hair
- Deepening of the voice
- Appearance of acne due to increased oil and sweat production
- Nocturnal or unprovoked ejaculation (sometimes)
- Maturation of the testes, seminal vesicles, and prostate gland
