Unit 3Review Midterm

neuron

a nerve cell; the basic building block of our nervous system

dendrites

a nueron’s bushy, branching extensions that receives messages through its branches and conduct impulses towards the cell body 

axon

the neuron extension that passages messages through its branches to other neurons or to muscles or glands

myelin sheath

a fatty tissue layer segmentally encasings the axons of some neurons; enables the axons of some neuron; enables vastly greater transmission speed as neural impulses hop from one sausage like neuron to the next

action potential

 a neural impulse; a brief electrical charge that travels down an axon 

refractory period

a period of inactivity after the neuron has fired

threshold

the level of stimulation required to trigger an impulse

all or none response

 a neuron’s reaction of either firing or not firing, regardless of the intensity of the trigger 

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 the synaptic gap or synaptic cleft.

neurotransmitter

chemical messengers that cross 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 that neuron will generate a neural impulse.

reuptake

a neurotransmitter’s reabsorption by the sending neuron

endorphins

 “morphine within” – natural, opiate-like neurotransmitter linked to pain control and to pleasure 

agonist

a molecule that, by binding to a receptor site, stimulates a response 

nervous system

the body’s speedy, electrochemical communication network, 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 (CNS) to the rest of the body.

somatic nervous system

the division of the peripheral nervous that controls the body’s skeletal system 

autonomic nervous system

controls the glands and the organs. Has two systems, sympathetic and parasympathetic

sympathetic nervous system

arouses the body, half of the autonomic nervous system. Mobilizes energy in stressful situations.

parasympathetic nervous system

calms the body in stressful situations, this is done to preserve energy

endocrine system

the body’s slow chemical reaction system, set to secrete hormones into the blood stream 

hormones

chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream and to tissue

pituitary glands

the endocrine system’s most influential gland. Also called the “master gland” Under the influence of the hypothalamus, the pituitary gland regulates the growth and controls the other endocrine glands 

adrenal glands

a pair of glands that sit above the kidney and secrete hormones (epinephrine and norepinephrine) that help arouse in times of stress (adrenaline comes from this) 

lesion

tissue destruction. A brain lesion is the destruction of brain tissue. This is done either experimentally or can happen naturally 

EEG

an amplified recording of the waves of electrical activity sweeping across the brain’s surface. These waves are measured by electrodes placed on the scalp.

CT scan

a series of X-ray photographs taken from different angles and combined by computer into a composite representation of a slice of the brain’s structure. (Also called CAT scan.)

PET scan

a visual display of brain activity that detects

where a radioactive form of glucose goes while the brain performs a given task.

MRI

 a technique that uses magnetic fields and radio waves

to produce computer-generated images of soft tissue. MRI scans show brain anatomy.

fMRI (functional MRI)

a technique for revealing bloodflow and, therefore, brain activity by comparing successive MRI scans. fMRI scans show brain function as well as its structure.

brainstem

 the oldest part and central part of the brain, beginning where the spinal cord swells as it enters the skull; the brain stem is responsible for automatic survival functions 

medulla

 the base of the brain stem, controls heartbeat and breathing

thalamus

the brain’s sensory control center, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum

and medulla.

pons

coordinates movement

reticular formation

a nerve network that travels through the brainstem and thalamus and plays an important role in controlling arousal.

cerebellum

 the “little brain” at the rear of the brainstem; functions include processing sensory input, coordinating movement output and balance, and enabling nonverbal learning and memory.

limbic system

 neural system (including the hippocampus, amygdala, and hypothalamus) located below the cerebral hemispheres; associated with emotions and drives.

amygdala

 two lima bean sized neural clusters in the limbic system; linked to emotion

hypothalamus

 a neural structure lying below (hypo) the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward.

corpus collosum

connects the two hemispheres of the brain

cerebellum

 the intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body’s ultimate control and information-processing center

dual processing

the principle that information is often simultaneously processed on separate conscious and unconscious tracks.

consciousness

 our awareness of ourselves and our environments

split brain

\n  a condition resulting from surgery that isolates the brain’s two hemispheres by cutting the fibers (mainly those of the corpus callosum) connecting them.

left brain

handles creative thinking and problem solving

right brain

handles sense of self and and makes inferences and handles perceptual tasks 

behavior genetics

the study of the relative power and limits of genetics and environmental influences on behavior 

heritability

the proportion of variation among individuals that we can attribute to genes. The heritability of a trait may vary, depending on the range of populations and environments studied (IN A GROUP)

epigenetics

 the study of environmental influences on gene expression that occur without a DNA change

mutations

a random error in gene replication that leads to a change