Module 3 Q & A

What happens in the synaptic gap?

An action potential travels down a neurons axon to the axon terminal where it then releases ligands (neurotransmitters) in the synaptic gap. The receiving neuron take up the released neurotransmitters via ligand gated ion channels (receptor sites) where electrically charged ions can now flow in, exciting or inhibiting the receiving neurons readiness to fire. (depolarization of the dendrites causes a current thus generating a voltage, if the voltage of all of them (summation) is strong enough then the neuron could fire another action potential).

How are the nervous and endocrine systems alike, and how do they differ?

Both of these communication systems produce chemical molecules that act on the body's receptors to influence our behavior and emotions. The endocrine system, which secretes hormones into the bloodstream, delivers its messages much more slowly than the speedy nervous system, and the effects of the endocrine system's messages tend to linger much longer than those of the nervous system.

What are neurons, and how do they transmit information?

Neurons are the basic building blocks of the nervous system, the body's speedy electrochemical information system. A neuron receives signals through its branching dendrites, and sends signals through its axons. Some axons are encased in a myelin sheath, which enables faster transmission. Glial cells provide myelin, and they support, nourish, and protect neurons; they may also play a role in learning and thinking. If the combined signals received by a neuron exceed a minimum threshold (about negative 55 millivolts), the neuron fires, transmitting an electrical impulse (the action potential) down its axon by means of a chemistry-to-electricity process. The neuron's reaction is an all-or-none process. Absolute or relative refractory periods are tiny (millisecond) breaks between action potentials.

How do neurotransmitters influence behavior, and how do drugs and other chemicals affect neurotransmission?

Neurotransmitters travel designated pathways in the brain and may influence specific behaviors and emotions. Acetylcholine (ACh) affects muscle action, learning, and memory. Endorphins are natural opiates released in response to pain and exercise. Drugs and other chemicals affect brain chemistry at synapses. Agonists increase a neurotransmitter's action, and may do so in various ways. Antagonists decrease a neurotransmitter's action by blocking production or release.

Why are psychologists concerned with human biology?

Psychologists working from a biological perspective study the links between biology and behavior. We are biopsychosocial systems, in which biological, psychological, and social-cultural factors interact to influence behavior. Biological responses affect our behavior and mental processes.

Why is the pituitary gland called the "master gland"?

Responding to signals from the hypothalamus, the pituitary releases hormones that trigger other endocrine glands to secrete hormones, which in turn influence brain and behavior.

What bodily changes does your ANS direct before and after you give an important speech?

Responding to this challenge, your ANS sympathetic division will arouse you. It accelerates your heartbeat, raises your blood pressure and blood sugar, slows your digestion, and cools you with perspiration. After you give the speech, your ANS parasympathetic division will reverse these effects.

What is reuptake? What two other things can happen to excess neurotransmitters after a neuron reacts?

Reuptake occurs when excess neurotransmitters are reabsorbed by the sending neuron. They can also drift away or be broken down by enzymes.

How do nerve cells communicate with other nerve cells?

When action potentials reach the end of an axon (the axon terminals), they stimulate the release of neurotransmitters. These chemical messengers carry a message from the sending neuron across a synapse to receptor sites on a receiving neuron. The sending neuron, in a process called reuptake, then normally reabsorbs the excess neurotransmitter molecules in the synaptic gap. If incoming signals are strong enough, the receiving neuron generates its own action potential and relays the message to other cells.