MCAT Psychological Social Foundations Flashcards: 7a Biological Bases Behavior

What this deck covers

This deck focuses on 7a Biological Bases Behavior, giving you a quick way to review the definitions, rules, and examples that matter most for MCAT Psychological Social Foundations.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: What is the primary neurotransmitter released by most sympathetic postganglionic neurons?

Answer: Norepinephrine. NE binds adrenergic receptors for sympathetic effects.

Flashcard 2: Which ANS division mediates "rest-and-digest" functions?

Answer: Parasympathetic nervous system. Promotes energy conservation and digestion when relaxed.

Flashcard 3: What is the primary function of the Na$^+$/K$^+$ ATPase in neurons?

Answer: Maintains ion gradients across the membrane. Pumps 3 Na$^+$ out and 2 K$^+$ in, maintaining resting potential.

Flashcard 4: Which endocrine gland releases epinephrine and norepinephrine into the bloodstream?

Answer: Adrenal medulla. Part of sympathetic response, releasing stress hormones systemically.

Flashcard 5: Which PNS division controls skeletal muscle (voluntary) movement?

Answer: Somatic nervous system. Controls voluntary movements via motor neurons to skeletal muscles.

Flashcard 6: What is the main endocrine effect of thyroid hormones $T_3$ and $T_4$?

Answer: Increase basal metabolic rate. Regulate cellular metabolism and heat production throughout body.

Flashcard 7: What is the role of the Na+/K+ ATPase in neurons?

Answer: Maintains $\text{Na}^+$ and $\text{K}^+$ gradients using ATP. Pumps 3 $\text{Na}^+$ out and 2 $\text{K}^+$ in per cycle.

Flashcard 8: What are the two branches of the autonomic nervous system (ANS)?

Answer: Sympathetic and parasympathetic. ANS splits into opposing branches for homeostatic balance.

Flashcard 9: Which ion's efflux primarily causes the repolarization phase of an action potential?

Answer: K$^+$ efflux. K$^+$ channels open after Na$^+$ channels, restoring negative potential.

Flashcard 10: What ion influx is primarily responsible for the depolarization phase of an action potential?

Answer: Sodium ($Na^+$) influx through voltage-gated sodium channels. Opening of $Na^+$ channels drives membrane toward positive.

Flashcard 11: What are the three major parts of a neuron?

Answer: Dendrites, soma (cell body), axon. These structures process, integrate, and transmit neural signals.

Flashcard 12: What is the immediate effect of parasympathetic activation on gastrointestinal motility?

Answer: Increases gastrointestinal motility and secretion. Enhances digestion when body is at rest.

Flashcard 13: Which autonomic division mediates "fight-or-flight," and what is its primary neurotransmitter at target organs?

Answer: Sympathetic; mainly norepinephrine at most target organs. Sympathetic activation prepares for stress responses, with norepinephrine binding adrenergic receptors to elicit effects.

Flashcard 14: Which ion influx primarily causes depolarization during a neuronal action potential?

Answer: Sodium ($Na^+$) influx. Opens voltage-gated channels making membrane more positive.

Flashcard 15: Which ion influx primarily causes depolarization during an action potential?

Answer: Sodium ($Na^+$) influx through voltage-gated channels. Opening of $Na^+$ channels makes membrane more positive.

Flashcard 16: What ion efflux is primarily responsible for the repolarization phase of an action potential?

Answer: Potassium ($K^+$) efflux through voltage-gated potassium channels. Opening of $K^+$ channels returns membrane to negative.

Flashcard 17: What is the difference between gray matter and white matter in the nervous system?

Answer: Gray: cell bodies/synapses; White: myelinated axon tracts. Gray contains processing centers; white contains communication pathways.

Flashcard 18: What is the myelin sheath's main effect on action potential conduction?

Answer: Increases conduction velocity. Insulation allows action potentials to jump between nodes (saltatory conduction).

Flashcard 19: What are nodes of Ranvier, and what is their key role in signaling?

Answer: Myelin gaps enabling saltatory conduction. Action potentials jump between these unmyelinated segments.

Flashcard 20: What is the term for the myelin-producing cell type in the CNS?

Answer: Oligodendrocyte. Forms myelin sheaths around CNS axons for faster conduction.

Flashcard 21: Which brain region is the primary homeostatic control center linking nervous and endocrine systems?

Answer: Hypothalamus. Controls pituitary hormones and autonomic functions.

Flashcard 22: What is saltatory conduction?

Answer: Action potentials "jump" node-to-node along myelinated axons. In myelinated axons, action potentials regenerate only at nodes, enabling efficient, rapid transmission over long distances.

Flashcard 23: Which glial cell type myelinates axons in the central nervous system?

Answer: Oligodendrocytes. Each cell can myelinate multiple axon segments in brain and spinal cord.

Flashcard 24: What is saltatory conduction?

Answer: AP propagation by jumping between nodes of Ranvier on myelinated axons. Myelin insulation forces current to flow between gaps.

Flashcard 25: What is the primary function of the axon in a neuron?

Answer: Transmit action potentials away from the soma. It's the output structure that propagates electrical signals.

Flashcard 26: What type of feedback loop most commonly regulates endocrine hormone levels?

Answer: Negative feedback. High hormone levels inhibit further release for homeostasis.

Flashcard 27: Which pituitary lobe secretes tropic hormones such as TSH, ACTH, LH, and FSH?

Answer: Anterior pituitary. Produces hormones that regulate other endocrine glands.

Flashcard 28: What is the primary function of a neuron's axon?

Answer: Transmit action potentials away from the soma. The axon carries electrical signals from the cell body to terminals.

Flashcard 29: What is the major inhibitory neurotransmitter in the adult brain?

Answer: GABA. GABA opens $Cl^-$ channels to hyperpolarize neurons.

Flashcard 30: Which autonomic division is primarily responsible for "fight-or-flight" responses?

Answer: Sympathetic nervous system. Activates during stress: increases heart rate, dilates pupils, releases glucose.

Flashcard 31: Which hormone is released by the pineal gland to regulate circadian rhythms?

Answer: Melatonin. Secreted at night to promote sleep and regulate sleep-wake cycles.

Flashcard 32: What is the role of the pituitary gland in endocrine signaling?

Answer: Secretes hormones under hypothalamic control to regulate other glands. "Master gland" releases tropic hormones affecting target endocrine organs.

Flashcard 33: What are the glial cells that myelinate axons in the central nervous system?

Answer: Oligodendrocytes. Form myelin sheaths in brain and spinal cord.

Flashcard 34: What is the key functional difference between the somatic and autonomic nervous systems?

Answer: Somatic controls voluntary skeletal muscle; autonomic controls involuntary organs. Somatic is conscious control; autonomic is unconscious regulation.

Flashcard 35: What is the primary physiological effect of antidiuretic hormone (ADH)?

Answer: Increases water reabsorption in the kidneys. Conserves body water by reducing urine production.

Flashcard 36: Which endocrine gland releases $T_3$ and $T_4$ to increase basal metabolic rate?

Answer: Thyroid gland. Thyroid hormones increase cellular metabolism throughout body.

Flashcard 37: What is the major excitatory neurotransmitter in the brain?

Answer: Glutamate. Glutamate binds NMDA/AMPA receptors to depolarize neurons.

Flashcard 38: What are the three major parts of a typical neuron (by name)?

Answer: Dendrites, soma (cell body), axon. These structures receive, integrate, and transmit neural signals respectively.

Flashcard 39: Which neurotransmitter is classically associated with skeletal muscle contraction?

Answer: Acetylcholine. ACh binds nicotinic receptors at neuromuscular junctions.

Flashcard 40: Which autonomic division mediates "rest-and-digest," and what is its primary neurotransmitter at target organs?

Answer: Parasympathetic; acetylcholine at target organs. Parasympathetic promotes conservation and recovery, using ACh on muscarinic receptors for inhibitory actions.

Flashcard 41: What is the term for the myelin-producing cell type in the PNS?

Answer: Schwann cell. Forms myelin sheaths around PNS axons for faster conduction.

Flashcard 42: What is the primary neurotransmitter released by parasympathetic postganglionic neurons?

Answer: Acetylcholine. ACh binds muscarinic receptors for parasympathetic effects.

Flashcard 43: What is the absolute refractory period?

Answer: Interval when no new AP can be generated (Na$^+$ channels inactivated). Ensures unidirectional propagation of action potentials.

Flashcard 44: What is the key functional difference between sympathetic and parasympathetic divisions?

Answer: Sympathetic: fight-or-flight; Parasympathetic: rest-and-digest. Sympathetic activates stress response; parasympathetic promotes recovery.

Flashcard 45: What is the all-or-none principle of an action potential?

Answer: Once threshold is reached, AP occurs with fixed amplitude. Ensures reliable signal transmission regardless of stimulus strength.

Flashcard 46: Which ANS division is characterized by "rest-and-digest" responses?

Answer: Parasympathetic nervous system. Conserves energy and promotes recovery when relaxed.

Flashcard 47: What endocrine gland releases epinephrine as part of the acute stress response?

Answer: Adrenal medulla. Part of sympathetic response, releases catecholamines.

Flashcard 48: Which brain structure is primarily responsible for homeostasis and endocrine regulation via the pituitary?

Answer: Hypothalamus. Links nervous and endocrine systems through releasing hormones.

Flashcard 49: Which adrenal region secretes cortisol as part of the long-term stress response?

Answer: Adrenal cortex (zona fasciculata). Responds to ACTH stimulation during chronic stress.

Flashcard 50: What brain structure is the primary homeostatic control center linking to the endocrine system?

Answer: Hypothalamus. Integrates neural and hormonal signals, controls pituitary output.

Flashcard 51: Which ion efflux is primarily responsible for the repolarization phase of an action potential?

Answer: Potassium ($K^+$) efflux through voltage-gated potassium channels. $K^+$ channels open later, restoring negative membrane potential.

Flashcard 52: Which endocrine gland secretes epinephrine and norepinephrine as part of the stress response?

Answer: Adrenal medulla. Modified sympathetic ganglion releasing catecholamines directly.

Flashcard 53: What structure allows saltatory conduction by separating myelinated segments?

Answer: Nodes of Ranvier. Unmyelinated gaps where action potentials regenerate.

Flashcard 54: What is the primary effect of an inhibitory postsynaptic potential (IPSP)?

Answer: Hyperpolarizes postsynaptic membrane, decreasing likelihood of firing. Makes membrane potential more negative, farther from threshold.

Flashcard 55: What is the direct effect of acetylcholine at the neuromuscular junction?

Answer: Binds nicotinic receptors and depolarizes the muscle end plate. Opens ligand-gated Na$^+$ channels causing muscle contraction.

Flashcard 56: What is the primary inhibitory neurotransmitter in the central nervous system?

Answer: GABA. GABA activates chloride channels, hyperpolarizing neurons to inhibit action potential generation.

Flashcard 57: Identify the neuron structure that receives incoming synaptic signals from other neurons.

Answer: Dendrites. Branch-like extensions that increase surface area for signal reception.

Flashcard 58: What is the function of the sodium-potassium pump in neurons?

Answer: Maintains gradients by pumping $3Na^+$ out and $2K^+$ in. Uses ATP to restore resting potential ion distribution.

Flashcard 59: What neurotransmitter is released by most sympathetic postganglionic neurons?

Answer: Norepinephrine. NE is the primary sympathetic neurotransmitter at target organs.

Flashcard 60: What is the neurotransmitter released by all autonomic preganglionic neurons?

Answer: Acetylcholine. Both ANS branches use ACh at ganglionic synapses.

Flashcard 61: Which neurotransmitter is most strongly associated with neuromuscular junction signaling?

Answer: Acetylcholine (ACh). ACh binds nicotinic receptors causing muscle contraction.

Flashcard 62: Which ion efflux primarily causes repolarization during a neuronal action potential?

Answer: Potassium ($K^+$) efflux. Opens after $Na^+$ channels to restore negative potential.

Flashcard 63: What is the primary role of myelin in neural signaling?

Answer: Increases conduction velocity by insulating the axon. Prevents ion leakage, forcing signal to jump between nodes.

Flashcard 64: Identify the endocrine gland that secretes insulin and glucagon to regulate blood glucose.

Answer: Pancreas (islets of Langerhans). Beta cells secrete insulin; alpha cells secrete glucagon.

Flashcard 65: Which autonomic division is characterized by "rest-and-digest" physiology?

Answer: Parasympathetic nervous system. Conserves energy and promotes digestion when relaxed.

Flashcard 66: What is the primary function of the sodium-potassium pump at rest?

Answer: Maintains gradients by moving $3Na^+$ out and $2K^+$ in. Uses ATP to maintain resting potential of approximately -70mV.

Flashcard 67: Identify the ion movement that primarily causes depolarization in an action potential.

Answer: Voltage-gated $\text{Na}^+$ influx. Opening of channels makes membrane potential more positive.

Flashcard 68: What is the typical direction of information flow in a neuron?

Answer: Dendrites  soma  axon  axon terminals. Signal travels from input region to output region unidirectionally.

Flashcard 69: What is the primary function of the somatic nervous system (SNS)?

Answer: Voluntary control of skeletal muscles; sensory to CNS. SNS controls conscious movements and relays sensory information.

Flashcard 70: Which ANS branch is associated with "rest-and-digest" physiology?

Answer: Parasympathetic nervous system. Promotes energy conservation and digestion when relaxed.

Flashcard 71: What is saltatory conduction?

Answer: Action potentials "jump" between nodes of Ranvier on myelinated axons. Rapid signal propagation by skipping myelinated segments.

Flashcard 72: What ion movement primarily causes the rapid upstroke of an action potential?

Answer: Na$^+$ influx through voltage-gated Na$^+$ channels. Rapid Na$^+$ entry creates a positive feedback loop, driving the membrane potential toward Na$^+$ equilibrium.

Flashcard 73: What is the primary function of dendrites in a neuron?

Answer: Receive incoming signals from other neurons. They're the input structures with receptors for neurotransmitters.

Flashcard 74: What type of receptor binds acetylcholine at the neuromuscular junction?

Answer: Nicotinic acetylcholine receptor. Ion channel receptor that triggers muscle contraction when activated.

Flashcard 75: Identify the neurotransmitter released by parasympathetic postganglionic neurons.

Answer: Acetylcholine. ACh binds muscarinic receptors for parasympathetic effects.

Flashcard 76: What is the main functional role of interneurons (association neurons)?

Answer: Integrate information within the CNS between neurons. They connect sensory and motor neurons for processing.

Flashcard 77: Identify the hormone that lowers blood glucose by increasing cellular uptake and glycogenesis.

Answer: Insulin. Promotes glucose storage when blood sugar is elevated.

Flashcard 78: Which autonomic branch is classically described as "rest-and-digest"?

Answer: Parasympathetic nervous system. Slows heart rate, constricts pupils, and promotes digestion.

Flashcard 79: Which nervous system division is primarily responsible for rest-and-digest functions?

Answer: Parasympathetic nervous system. Uses acetylcholine to slow heart rate, promote digestion.

Flashcard 80: What is the basic functional unit of the nervous system that transmits electrical signals?

Answer: Neuron. Neurons specialize in rapid signal transmission via electrochemical gradients, forming the foundation for nervous system communication.

Flashcard 81: What is the primary function of the autonomic nervous system (ANS)?

Answer: Involuntary regulation of glands, smooth and cardiac muscle. ANS operates without conscious control for internal organ function.

Flashcard 82: Identify the endocrine gland that secretes $T_3$ and $T_4$ to increase basal metabolic rate.

Answer: Thyroid gland. Thyroid hormones regulate metabolism and energy production.

Flashcard 83: What is the primary functional difference between the central and peripheral nervous systems?

Answer: CNS integrates/processes; PNS carries signals to and from CNS. CNS is the brain/spinal cord; PNS is all nerves outside CNS.

Flashcard 84: Which neurotransmitter is most strongly linked to reward and motivation pathways?

Answer: Dopamine. Key player in addiction and Parkinson's disease.

Flashcard 85: What is the immediate ionic cause of the depolarization phase of an action potential?

Answer: Voltage-gated $Na^+$ channels open; $Na^+$ influx. Rapid sodium entry makes the inside of the cell more positive.

Flashcard 86: What is the primary function of the peripheral nervous system (PNS)?

Answer: Transmits signals between CNS and body. Nerves carry sensory and motor information to/from the CNS.

Flashcard 87: What is the primary endocrine function of the anterior pituitary gland?

Answer: Secretes hormones in response to hypothalamic releasing hormones. Acts as relay between hypothalamus and target glands.

Flashcard 88: Which adrenal region secretes epinephrine and norepinephrine during acute stress?

Answer: Adrenal medulla. Functions as modified sympathetic ganglia releasing catecholamines.

Flashcard 89: Identify the process by which neurotransmitter is released into the synaptic cleft.

Answer: Calcium-triggered vesicular exocytosis. $Ca^{2+}$ influx causes vesicles to fuse with membrane.

Flashcard 90: What is the main distinction between endocrine and nervous signaling?

Answer: Endocrine: hormones in blood; nervous: electrochemical synapses. Speed differs: hormones are slower but longer-lasting.

Flashcard 91: What is the resting membrane potential of a typical neuron (approximate value)?

Answer: Approximately $-70\ \text{mV}$. Maintained by Na$^+$/K$^+$ pump and ion permeability differences.

Flashcard 92: What is the definition of an excitatory postsynaptic potential (EPSP)?

Answer: Postsynaptic depolarization increasing firing likelihood. Makes membrane potential less negative, closer to action potential threshold.

Flashcard 93: What is the primary function of the somatic nervous system?

Answer: Voluntary control of skeletal muscles and somatic sensory input. Somatic means voluntary; controls conscious movements and sensations.

Flashcard 94: Which glial cell myelinates axons in the central nervous system (CNS)?

Answer: Oligodendrocytes. Each oligodendrocyte can myelinate multiple CNS axons.

Flashcard 95: What neurotransmitter is released by parasympathetic postganglionic neurons?

Answer: Acetylcholine. ACh activates parasympathetic target organs.

Flashcard 96: Identify the neurotransmitter most associated with neuromuscular junction signaling.

Answer: Acetylcholine. Binds nicotinic receptors to trigger muscle contraction.

Flashcard 97: What is the synapse, and where do neurotransmitters act?

Answer: Junction where neurotransmitters bind receptors on the postsynaptic membrane. Synapses facilitate chemical communication, with neurotransmitters modulating postsynaptic excitability via receptor binding.

Flashcard 98: What is the all-or-none principle for action potentials?

Answer: AP occurs only if threshold is reached; size is constant. Like a light switch - either fully on or off, no in-between.

Flashcard 99: What is the main effect of cortisol released from the adrenal cortex during stress?

Answer: Increases blood glucose and mobilizes energy stores. Glucocorticoid that promotes gluconeogenesis and protein breakdown.

Flashcard 100: Identify the neurotransmitter released by most sympathetic postganglionic neurons.

Answer: Norepinephrine. NE binds adrenergic receptors for sympathetic effects.