CHAPTER 2: THE BIOLOGICAL PERSPECTIVE

NEURONS AND NERVES

Building network

Neurons

are individual cells in the nervous system that receive, integrate, and transmit information. They are the basic links that permit communication within the nervous system.

soma

cell body, contains the cell nucleus and much of the chemical machinery common to most cells (soma is Greek for "body").

dendritic trees

number of branched, feeler-like structures called __. is a Greek word for "tree").

Dendrites

Each individual branch is a___ and are the parts of a neuron that are specialized to receive information.

THE AXON

IS A LONG, THIN FIBER THAT TRANSMITS SIGNALS AWAY FROM THE SOMA TO OTHER NEURONS OR TO MUSCLES OR GLANDS. BRANCH OFF TO COMMUNICATE WITH A NUMBER OF OTHER CELLS.

MYELIN SHEATH

IS INSULATING MATERIAL THAT ENCASES SOME AXONS

Myelin

IN HUMANS, MANY AXONS ARE WRAPPED IN CELLS WITH A HIGH CONCENTRATION OF A WHITE, FATTY SUBSTANCE CALLED ___

neurotransmitters

The axon ends in a cluster of terminal buttons, which are small knobs that secrete chemicals that transmit information from one neuron to another called

These chemicals serve as messengers that may activate neighboring neurons.

Neurotransmitters

synapses

The points at which neurons interconnect are called __ where it is a junction where information is transmitted from one neuron to another (synapse is from the Greek for "junction").

Glia

are cells found throughout the nervous system that provide various types of support for neurons. (literally "glue") tend to be much smaller than neurons.

glial cells

serve many functions. For example, they supply nourishment to neurons, help remove neurons' waste products, and provide insulation around many axons.

EQUAL

recent research suggests that the human brain consists of roughly ___numbers of neurons and glial cells (Azevedo et al., 2009).

play a complicated role in the development of the nervous system in the human embryo and in the production of myelin

glial cells

THE NEURAL IMPULSE:

USING ENERGY TO SEND INFORMATION

A Tiny Battery

The Neuron at rest:

The resting potential of a neuron

is its stable, negative charge when the cell is inactive.

An action potential

is a very brief shift in a neuron's electrical charge that travels along an axon.

The absolute refractory period

is the minimum length of time after an action potential, during which another action potential cannot begin.

The synapse

Where Neurons meet

Chemicals as Couriers

synapses send signals through

synaptic cleft

a microscopic gap between the terminal button of one neuron and the cell membrane of another neuron. making two neurons not to touch each other.

action potential

the arrival of an ____at an axon's terminal buttons triggers the release of neurotransmitters

synaptic vesicles

___ contains neurotransmitters

Postsynaptic Potentials

Receiving Signals where a voltage change at a receptor site on a postsynaptic cell membrane.

When a neurotransmitter and a receptor molecule combine, reactions in the cell membrane cause a

postsynaptic potential (PSP)

excitatory or inhibitory effects

The _______ produced at a synapse last only a fraction of a second.

Reuptake

Most are reabsorbed into the presynaptic neuron through ____, a process in which neurotransmitters are sponged up from the synaptic cleft by the presynaptic membrane

Enzymes

Then neurotransmitters drift away from receptor sites or are inactivated by ____ that metabolize (convert) them into inactive forms.

release by motor neurons controlling skeletal. regulation of attention, arousal, memory.. Some stimulated by nicotine.

Acethylcholine (ACh)

Dopamine (DA)

control of voluntary movements "reward pathway"

cocaine and amphetamines

elevate activity at DA synapses and NE synapses

Norepinephrine (NE)

modulation of mood and arousal

serotonin

regulation of sleep and wakefulness, eating, and aggressive behavior

prozac and antidepressant drugs

affect serotonin circuits

inhibitory transmitter, regulation of anxiety and sleep/arousal

GABA

Valium and antianxiety

drugs that work in GABA synapses

endorphins

resemble opiate drugs (structure and effects) pain relief and response to stress, regulation of eating behavior

acetylcholine (ACh)

The discovery that cells communicate by releasing chemicals was first made in connection with the transmitter ___. ound throughout the nervous system. It is the only transmitter between motor neurons and voluntary muscles.

motor neurons

Every move you make—walking, talking, breathing—depends on ACh released to your muscles by _____ (Kandel & Siegelbaum, 2013)

is used by neurons that control voluntary movements. The degeneration of such neurons apparently causes Parkinson's disease.

Dopamine (DA)

dopamine, norepinephrine, and serotonin.

The monoamines include three neurotransmitters:

gamma-aminobutyric acid (GABA)

is notable in that it seems to produce only inhibitory postsynaptic potentials. appears to have inhibitory effects at virtually all synapses where it is present. Another group of transmitters consists of amino acids. (full abbreviated word_

GABA

is involved in the regulation of anxiety in humans, and that disturbances in ____circuits may contribute to some types of anxiety disorders (Long et al., 2013; Rosso et al., 2014

internally produced chemicals that resemble opiates in structure and effects. A search for the body's natural opiate ensued. Soon, a number of endogenous opioids were identified (Hughes et al., 1975)

endorphins

Nerves

are bundles of neuron fibers (axons) that are routed together in the peripheral nervous system.

peripheral nervous system

is made up of all those nerves that lie outside the brain and spinal cord. The first and most important division separates the central nervous system (the brain and spinal cord)

The somatic nervous system

lets you feel the world and move around in it. These nerves are the cables that carry information from receptorsin the skin, muscles, and joints to the central nervous system and that carry commands from the central nervous system to the muscles.

voluntary skeletal muscles and to sensory receptors.

The somatic nervous system is made up of nerves that connect to _____.

Afferent nerve fibers

are axons that carry information inward to the central nervous system from the periphery of the body.

Efferent nerve fibers

are axons that carry information outward from the central nervous system to the periphery of the body.

Efferent nerve fibers and Afferent nerve fibers

two types of somatic nerves

The Autonomic Nervous System

is made up of nerves that connect to the heart, blood vessels, smooth muscles, and glands. controls automatic, involuntary, visceral functions that people don't normally think about, such as heart rate, digestion, and perspiration (Powley, 2008).

central nervous system

the autonomic system is a separate (autonomous) system, although it is ultimately controlled by the ____.

sympathetic division

is the branch of the autonomic nervous system that mobilizes the body's resources for emergencies. It creates the fight-or-flight response. slows digestive processes and drains blood from the periphery, lessening bleeding in the case of an injury.

Key sympathetic nerves

send signals to the adrenal glands, triggering the release of hormones that ready the body for exertion.

parasympathetic division

is the branch of the autonomic nervous system that generally conserves bodily resources. It activates processes that allow the body to save and store energy

sympathetic and parasympathetic divisions

branches of autonomic nervous system

is the portion of the nervous system that lies within the skulland spinal column. consists of the brain and the spinal cord.

central nervous system

cerebrospinal fluid (CSF)

The CNS is bathed in its own special nutritive "soup," called ___.

This fluid nourishes the brain and provides a protective cushion for it.

cerebrospinal fluid (CSF)

blood-brain barrier

To enter the CSF, substances in the blood have to cross the ___, a semipermeable membrane that stops some chemicals, including drugs, from leaving the bloodstream to enter the brain.

spinal cord

connects the brain to the rest of the body through the peripheral nervous system

brain

crowning glory of the central nervous system. that fills the upper portion of the skull. t weighs only about 3 pounds and could be held in one hand. contains billions of interacting cells that integrate information from inside and outside the body; coordinate the body's actions; and enable people to talk, think, remember, plan, create, and dream.

Lesioning

involves destroying a piece of the brain. It is typically done by inserting an electrode into a brain structure and passing a high-frequency electric current through it to burn the tissue and disable the structure.

Electrical stimulation of the brain (ESB)

technique which involves sending a weak electric current into a brain structure to stimulate (activate) it.

brain and spiral cord

parts of central nervous system

Lesioning and electrical stimulation of the brain (ESB)

research method inside the brain are methods of disabling the brain for research purposes.

hindbrain

the cerebellum and two structures found in the lower partof the brainstem: the medulla and the pons.

medulla

which attaches to the spinal cord, controls largely unconscious but essential functions, such as breathing, maintainingmuscle tone, and regulating circulation.

pons

The ____ (literally "bridge") includes a bridge of fibers that connects the brainstem with the cerebellum. it also contains several clusters of cell bodies involved with sleep and arousal.

The cerebellum

("little brain") is a relatively large and deeply folded structure adjacent to the back surface of the brainstem. it is involved in the coordination of movement and is critical to the sense of equilibrium, or physical balance (Lisberger & Thach, 2013).

midbrain

is the segment of the brainstem that lies between the hindbrain and the forebrain. contains an area that is concerned with integrating sensory processes, such as vision and hearing (Stein, Wallace, & Stanford, 2000).

forebrain

is the largest and most complex region of the brain, encompassing a variety of structures, including the thalamus, hypothalamus, limbic system, and cerebrum.

thalamus

is a structure in the forebrain through which all sensory information (except smell) must pass to get to the cerebral cortex. A relay Station

cell bodies, or somas.

thalamus is made up of number of clusters of

Hypothalamus

is a structure found near the base of the forebrain that is involved in the regulation of basic biological needs. It lies beneath the thalamus. A Regulator of Biological Needs

limbic system

the seat of emotions. is a loosely connected network of structures located roughly along the border between the cerebral cortex and deeper subcortical areas.

edge"

(hence the term limbic, which means __).

Paul MacLean (1954)

First described by ___, the limbic system is not a welldefined anatomical system with clear boundaries. Broadly speaking, it includes parts of the thalamus and hypothalamus, the hippocampus, the amygdala, and other nearby structures.

hippocampus and adjacent structures

clearly play a role in memory processes (Eichenbaum, 2013).

hippocampal region

Some theorists believe that the _____ is responsible for the consolidation of memories for factual information and perhaps other types of memories (Albouy et al., 2013).

amygdala

may play a central role in the learning of fear responses and the processing of other basic emotional responses (LeDoux & Damasio, 2013; Phelps, 2006).

cerebrum

The Seat of Complex Thought. is the largest and most complex part of the human brain. It includes the brain areas that are responsible for our most complex mental activities, including learning, remembering, thinking, and consciousness itself.

cerebral cortex

is the convoluted outer layer of the cerebrum.

hemispheres

cerebrum is divided into two halves, called _____. Hence, the cerebral hemispheres are the right and left halves of the cerebrum.

cerebral hemispheres

are separated in the center of the brain by the longitudinal fissure (a split or crevice) that runs from the front to the back.

corpus callosum.

fissure (a split or crevice) that runs from the front to the back. This fissure descends to a thick band of fibers called the__. is the major structure that connects the two cerebral hemispheres

occipital lobe

at the back of the head, includes the cortical area where most visual signals are sent and visual processing is begun.

primary visual cortex

visual signals are sent and visual processing is begun. This area is called the ___.

parietal lobe

is forward of the occipital lobe. It includes the area that registers the sense of touch. is also involved in integrating visual input and in monitoring the body's position in space.

primary somatosensory cortex

area that registers the sense of touch, called the ____.

temporal lobe

(meaning "near the temples") lies below the parietal lobe. Near its top, IT contains an area devoted to auditory processing, the primary auditory cortex.

primary auditory cortex.

area devoted to auditory processing, the

speech and language.

As we will see momentarily, damage to an area in the temporal lobe on the left side of the brain can impair the ability to comprehend

frontal lobe

the largest lobe in the human brain. It contains the principal areas that control the movement of muscles, the primary motor cortex. Electrical stimulation applied in these areas can cause actual muscle contractions.

diversity and precision

amount of motor cortex allocated to the control of a body part depends not on the part's size but on the ___ of its movements.

right Brain/Left Brain:

Cerebral specialization

Broca's area

plays an important role in the production of speech