Biological Basis of Behavior

Question 1

Fill in the blank.

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.

Answer 1

central, peripheral

These systems are often abbreviated CNS and PNS, respectively.

Question 2

What are the two structures that contain all the nerves within the central nervous system?

Answer 2

1. brain
2. spinal cord

Question 3

What division of the nervous system includes all nerves located outside the brain and spinal cord?

Answer 3

peripheral nervous system

Question 4

What are the two subsystems into which the peripheral nervous system is generally divided?

Hint: These divisions are delineated based on whether or not they require conscious input.

Answer 4

1. somatic nervous system
2. autonomic nervous system

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.

Question 5

Fill in the blank.

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.

Answer 5

autonomic, peripheral

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).

Question 6

Fill in the blank.

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.

Answer 6

somatic, peripheral

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).

Question 7

Fill in the blank.

The official name for the “fight-or-flight” division of the nervous system is the _________ nervous system.

Answer 7

sympathetic

It 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.

Question 8

What is the official name of the “rest-and-digest” division of the nervous system?

Answer 8

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.

Question 9

What branch of the autonomic nervous system inhibits peristalsis when activated?

Answer 9

sympathetic nervous system

Inhibition of peristalsis (and of digestive activity in general) is characteristic of the sympathetic, or fight-or-flight, nervous system.

Question 10

What branch of the autonomic nervous system is associated with increased secretion of saliva?

Answer 10

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).

Question 11

What branch of the autonomic nervous system is associated with an increase in blood glucose levels?

Answer 11

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.

Question 12

What branch of the autonomic nervous system is activated when pupils dilate?

Answer 12

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.

Question 13

What branch of the autonomic nervous system is associated with decreased blood flow to skeletal muscles?

Answer 13

parasympathetic nervous system

Overall, parasympathetic activation results in decreased blood flow to muscles and increased blood flow to the digestive system.

Question 14

What neurological circuit is shown in the image below?

Answer 14

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.

Question 15

Where do reflex arcs typically synapse, allowing them to bypass involvement of which structure?

Answer 15

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.

Question 16

Name the three types of nerve cells (neurons) in the human nervous system.

Answer 16

• motor neurons
• sensory neurons
• interneurons

Question 17

Describe:

The general function of sensory neurons.

Answer 17

They transmit sensory information (both external and internal) from the periphery of the body to the central nervous system.

Question 18

Describe:

The general function of motor neurons.

Answer 18

They 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.

Question 19

Name the type of neuron that is commonly found between a sensory neuron and a motor neuron in a reflex arc.

Answer 19

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.

Question 20

Fill in the blank.

A gap between neurons into which neurotransmitter molecules are released is termed a _________.

Answer 20

synapse

Interestingly, neurons do not directly contact each other. Instead, they are separated by small gaps termed synapses.

Question 21

How many neurons are involved in a monosynaptic reflex arc, and what type(s) of neurons are they?

Answer 21

Two neurons are involved in a monosynaptic reflex arc:

1. sensory neuron
2. motor neuron

“Monosynaptic” means “one synapse.” A synapse is a gap between neurons, so this reflex arc must involve two neurons.

Question 22

How many neurons are involved in a disynaptic reflex arc, and what type(s) of neurons are they?

Answer 22

Three neurons are involved in a disynaptic reflex arc:

1. sensory neuron
2. motor neuron
3. interneuron

“Disynaptic” means “two synapses.” To have two synapses (gaps between neurons), this reflex arc must involve three neurons.

Question 23

Fill in the blank.

Due to the direction in which they transmit information (from the periphery toward the brain), sensory neurons are also termed ________ neurons.

Answer 23

afferent

In general, “afferent” refers to movement or transmission toward a point of reference.

Question 24

True or false.

A neuron that transmits impulses from the spinal cord toward skeletal muscle fibers is an afferent neuron.

Answer 24

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.

Question 25

What molecules are responsible for **communication** between neurons and the **propagation** of nerve signals throughout the body?

Answer 25

neurotransmitters

Question 26

# True or false. GABA, serotonin, and epinephrine are inhibitory neurotransmitters.

Answer 26

False ## Footnote This statement is false because epinephrine is not inhibitory. **Excitatory** neurotransmitters include acetylcholine and epinephrine, while **inhibitory** neurotransmitters include dopamine, GABA, and serotonin.

Question 27

What neurotransmitter is strongly associated with feelings of euphoria and happiness and often contributes to addiction to recreational drugs? ## Footnote Many antidepressants function by inhibiting the reuptake of this neurotransmitter.

Answer 27

serotonin ## Footnote While both serotonin and dopamine are associated with feelings of euphoria, only serotonin is a treatment target for depression via selective serotonin reuptake inhibitors.

Question 28

# Fill in the blank. \_\_\_\_\_\_\_\_ neurons synthesize dopamine, while \_\_\_\_\_\_\_\_ receptors are stimulated by nicotine.

Answer 28

Dopaminergic, nicotinergic ## Footnote Defective dopaminergic neurons can cause impaired motor movements, loss of feelings, changes in mood, and impaired memory.

Question 29

List the **seven primary neurotransmitters** or neurotransmitter types used in the body.

Answer 29

1. Gamma-aminobutyric acid (GABA) 2. Acetylcholine 3. Epinephrine 4. Norepinephrine 5. Serotonin 6. Dopamine 7. Endorphins

Question 30

# Fill in the blank. The main inhibitory neurotransmitter in the adult human brain is \_\_\_\_\_-\_\_\_\_\_\_\_\_\_ \_\_\_\_\_.

Answer 30

gamma-aminobutyric acid | (GABA)

Question 31

What neurotransmitter is involved in the reward pathway that plays a crucial role in drug addiction? ## Footnote As an additional hint, neurons that produce it deteriorate in patients with Parkinson's disease.

Answer 31

dopamine ## Footnote 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.

Question 32

What neurotransmitter is alternatively known as **noradrenaline**?

Answer 32

norepinephrine ## Footnote Norepinephrine has many of the same effects as epinephrine (adrenaline), such as increasing heart rate and increasing blood glucose level.

Question 33

What neurotransmitter and hormone, also known as adrenaline, is administered to **stimulate heart rate** and **breathing** in patients experiencing extreme allergic reactions?

Answer 33

epinephrine ## Footnote Epinephrine, like norepinephrine, stimulates heart rate and breathing rate and is generally associated with the activity of the sympathetic nervous system.

Question 34

What neurotransmitters are responsible for the “runner’s high” that makes exercise appealing to many athletes?

Answer 34

endorphins ## Footnote Endorphins (the name of which essentially comes from "endogenous morphines") are pain-killing neurotransmitters released after injury or exercise.

Question 35

What neurotransmitter is targeted by a class of drugs known as SSRIs?

Answer 35

serotonin ## Footnote 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).

Question 36

What neurotransmitter serves as the main **parasympathetic** neurotransmitter and **stimulates muscle contraction** at the neuromuscular junction?

Answer 36

acetylcholine ## Footnote 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.

Question 37

# Fill in the blank. A person with severe problems balancing, standing upright, and exercising hand-eye coordination is likely to have a damaged \_\_\_\_\_\_\_\_\_.

Answer 37

cerebellum ## Footnote The cerebellum, located at the very rear of the brain, is the region most closely associated with balance, posture, and coordination.

Question 38

Name the most evolutionarily ancient part of the brain, which is continuous with the spinal cord.

Answer 38

brain stem ## Footnote 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.

Question 39

Name the specific part of the brain stem that is situated above the pons and that regulates heart rate, blood pressure, and breathing.

Answer 39

medulla oblongata ## Footnote 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.

Question 40

Name the three regions of the brain, named for their relative positions.

Answer 40

* forebrain * midbrain * hindbrain

Question 41

What region of the brain, also known as the prosencephalon, contains the cerebrum, thalamus, limbic system, and hypothalamus?

Answer 41

forebrain ## Footnote The forebrain regulates abstract thinking, logic, and emotions.

Question 42

What is the mesencephalon of the brain, which contains the tegmentum, tectum, and substantia nigra, also called?

Answer 42

midbrain ## Footnote The midbrain is responsible for dopamine production (habituation, motivation, and reward) and assists in visual and auditory processing.

Question 43

What part of the brain contains the cerebellum, medulla, and pons?

Answer 43

hindbrain ## Footnote The hindbrain is in charge of motor control, respiratory reflexes, gastrointestinal reflexes, and sexual arousal.

Question 44

What part of the forebrain primarily regulates homeostatic functions, such as water balance and metabolism?

Answer 44

hypothalamus ## Footnote The hypothalamus plays these roles primarily through both the production and the stimulation of hormones.

Question 45

What circulation-based structure connects the hypothalamus to the anterior pituitary gland?

Answer 45

hypophyseal portal system ## Footnote 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.

Question 46

What part of the forebrain receives and directs most sensory information to its appropriate destination?

Answer 46

thalamus ## Footnote The thalamus serves as a kind of "connecting station," receiving sensory information and relaying it to where it needs to go.

Question 47

What part of the forebrain is most closely involved in regulating sleep and wakefulness?

Answer 47

pineal gland ## Footnote The pineal gland produces melatonin, a hormone that regulates sleep/wake cycles.

Question 48

What group of nuclei, located deep in the brain, play a role in the smoothness of voluntary muscle movements and other functions?

Answer 48

basal ganglia ## Footnote 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.

Question 49

What larger set of brain structures includes the hippocampus, septal nuclei, nucleus accumbens, and amygdala?

Answer 49

limbic system ## Footnote 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.

Question 50

Which limbic system structure is most closely involved with the formation and consolidation of memory?

Answer 50

hippocampus ## Footnote The hippocampus, which is considered part of the limbic system, is primarily involved in the consolidation of short-term memory into long-term memory.

Question 51

How many lobes does the human brain contain?

Answer 51

four lobes

Question 52

What are the names of all the lobes of the human brain?

Answer 52

1. **frontal** lobe 2. **parietal** lobe 3. **temporal** lobe 4. **occipital** lobe

Question 53

Which lobe of the brain plays the greatest role in higher-level reasoning? ## Footnote Hint: This lobe does not fully develop until the individual is approximately 25 years old.

Answer 53

frontal lobe ## Footnote 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.

Question 54

# Fill in the blank. 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 \_\_\_\_\_\_\_ \_\_\_\_\_.

Answer 54

prefrontal cortex

Question 55

# Fill in the blank. The lobe of the brain that mainly functions to facilitate vision is the \_\_\_\_\_\_\_\_ lobe.

Answer 55

occipital ## Footnote The occipital lobe, located at the rear of the brain above the cerebellum, is the location of the visual cortex.

Question 56

The **somatosensory cortex** is found in which lobe of the brain?

Answer 56

parietal lobe ## Footnote 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.

Question 57

**Hearing, emotion, and memory** are all controlled at least in part by which brain lobe? ## Footnote Hint: This lobe is the location of the auditory cortex.

Answer 57

temporal lobe ## Footnote 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.

Question 58

# True or false. The left and right hemispheres share an equal burden of cortical function.

Answer 58

False ## Footnote **Lateralization** refers to the fact that our brain divides specific functions across each hemisphere unevenly, with each hemisphere predominantly performing certain functions.

Question 59

What **hemisphere of the brain** predominantly controls movement of the **right side** of the body and is typically associated with logic, language production, and analytic skills?

Answer 59

left hemisphere ## Footnote 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.

Question 60

What **hemisphere of the brain** predominantly controls movement of the **left side** of the body and is typically associated with spatial skills, emotion recognition, and creativity?

Answer 60

right hemisphere ## Footnote 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.

Question 61

# True or false. Functions related to the left side of the body that are controlled by the left hemisphere are under ipsilateral control.

Answer 61

True ## Footnote "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.

Question 62

What **imaging technique** uses computer-processed combinations of multiple X-ray measurements from various angles to produce cross-sectional images, or "slices," of specific areas of the brain?

Answer 62

CT/CAT scan ## Footnote These abbreviations stands for computed tomography and computerized axial tomography, respectively.

Question 63

What **imaging technique** is used to observe metabolic processes and blood flow? ## Footnote 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.

Answer 63

Positron-emission tomography | (PET)

Question 64

What **imaging technique** measures changes in blood flow to quantify brain activity in specific regions?

Answer 64

functional magnetic resonance imaging | FMRI ## Footnote The most common form of fMRI is termed fMRI BOLD, where "BOLD" stands for "blood oxygen level-dependent."

Question 65

# Fill in the blank. 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.

Answer 65

decrease, behavioral geneticists ## Footnote 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.

Question 66

What field of study focuses on the **modification of gene expression** without altering the overall genetic code?

Answer 66

epigenetics ## Footnote This allows the body to alter the phenotype without changing the genotype. Epigenetics are primarily influenced by environment.

Question 67

# Fill in the blank. The addition of \_\_\_\_\_\_\_ groups to DNA allows for gene silencing without directly affecting the genome itself.

Answer 67

methyl ## Footnote This process is termed DNA methylation.

Question 68

What **traits** would be expected to evolutionarily predominate over time in a species of rabbit living in an area with a large number of predators?

Answer 68

Over time, the environment would favor cautious, sneaky, fast-running, and/or quiet rabbits. ## Footnote Any traits that would increase the likelihood of a rabbit's escape/evasion from predators would be evolutionarily favored.

Question 69

Place the following human developmental stages in order: * conception * blastula * zygote * morula * embryo * fetus * newborn

Answer 69

conception → zygote → morula → blastula → embryo → fetus → newborn

Question 70

# 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.

Answer 70

walking reflex

Question 71

# 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.

Answer 71

palmar grasp reflex

Question 72

# 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.

Answer 72

tonic neck reflex

Question 73

# Name the reflex exemplified below. Stroking an infant's cheek causes the baby to turn towards the hand and open their mouth.

Answer 73

rooting reflex

Question 74

# Name the reflex exemplified below. If a bottle nipple touches the roof of an infant's mouth, the infant will begin to suck.

Answer 74

sucking reflex

Question 75

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

Answer 75

lift head while prone ## Footnote 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

Question 76

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

Answer 76

walking unassisted ## Footnote 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

Question 77

During what **age** range do children learn fundamental movements?

Answer 77

approximately **2-7 years old** ## Footnote During this time, the child begins to coordinate the limbs and can perform simple motor tasks, such as running, catching a ball, or jumping.

Question 78

During which **age** range do children develop what is called "specialized movement"?

Answer 78

approximately **7-14 years old** ## Footnote Children this age can use learned fundamental movements to complete specific actions (e.g. throwing a ball, riding a bike).

Question 79

Name the **standard female secondary sex characteristics** that develop during puberty.

Answer 79

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

Question 80

Name the **standard changes** associated with the onset of male adolescence.

Answer 80

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