1. Explain why psychologists are concerned with human biology.

  2. Describe the structure of a neuron, and explain how neural impulses are generated.

  3. Describe how nerve cells communicate, and discuss the impact of neurotransmitters and drugs on human behavior.

  4. Identify the major divisions of the nervous system and describe their functions, noting the three types of neurons that transmit information through the system.

  5. Contrast the simplicity of the neural pathways involved in reflexes with the complexity of neural networks.

  6. Describe the nature and function of the endocrine system and its interaction with the nervous system.

Key Vocabulary:

Biological psychology- a branch of psychology concerned with the links between biology and behavior.

Neuron- a nerve cell; the basic building block of the nervous system.

Dendrite- the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body.

Axon- the extension of a neuron, ending in branching terminal fibers, through which messages are sent to other neurons or to muscles or glands.

Myelin sheath- a layer of fatty tissues segmentally encasing the fibers transmission speed of neural impulses as the impulse hops from one node to the next.

Action potential- a neural impulse; a brief electrical charge that travels down an axon. The action potential is generated by the movement of positively charged atoms in and out of channels in the axon's membrane.

Threshold- the level of stimulation required to trigger a neural impulse.

Synapse- the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called synaptic gap or cleft.

Neurotransmitter- chemical messengers that traverse the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether it will generate a neural impulse.

Acetylcholine- a neurotransmitter that, among its function, triggers muscle contraction.

Endorphin-"morphine within"; natural, opiatelike neurotransmitter linked to pain control and to pleasure.

Nervous System- the body's speedy, electrochemical communication system, consisting of all the nerve cells of the peripheral and central nervous systems.

Central Nervous System- the brain and spinal cord.

Peripheral Nervous System- the sensory and motor neurons that connect the central nervous system to the rest of the body.

Nerves- neural "cables" containing many axons. These bundled axons, which are part of the peripheral nervous system, connect the central nervous system with muscles, glands, and sense organs.

Sensory Neurons- neurons that carry incoming information from the sense receptors to the central nervous system.

Interneurons- central nervous system neurons that internally communicate and intervene between the sensory inputs and motor outputs.

Motor Neurons- the neurons that carry outgoing information from the central nervous system to the muscles and glands.

Somatic Nervous System- the division of the peripheral nervous system that controls the body's skeletal muscles.

Autonomic Nerous System- the part of the peripheral nervous system that controls the glands and the muscles of the internal organs. Its sympathetic division arouses; its parasympathetic division calms.

Sympathetic Nervous System- the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations.

Parasympathetic Nervous System- the division of the autonomic nervous system that calms the body, conserving its energy.

Reflex- a simple, automatic, inborn response to a sensory stimulus, such as the knee-jerk response.

Neural networks- interconnected neural cells. With experience, networks can learn, as feedback strengthens or inhibits connections that produce certain results. Computer simulations of neural networks show analogous learning.

Endocrine System- the body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstream.

Hormones- chemical messengers, mostly those manufactured by the endocrine glands, that are produced in one tissue and affect another.

Adrenal Glands- a pair of endocrine glands just above the kidneys. The adrenals secrete the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline), which help to arouse the body of times of stress.

Pituitary Glands- the endocrine system's most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands.