Exam #2 Flashcards Preview

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Flashcards in Exam #2 Deck (48):
1

antagonist

a drug that blocks the effects of a neurotransmitter

2

agonist

a drug that increases the effects of a neurotransmitter

3

affinity

terms that describes a drugs bond to a receptor like a lock and key

4

efficacy

a drugs tendency to activate a receptor

5

nucleus accumbens

1. Almost all abused drugs stimulate dopamine release in the nucleus acumbens.
2. small subcortical area rich in dopamine receptors.
3. an area responsible for feelings of pleasure.

6

Olds & Milner (1954)

1. placed rats in a Skinner box that allowed self-stimulation of the brain by the pressing of a lever.
2. Rats sometimes pressed the lever 2000 times per hour to stimulated the release of dopamine in the nucleus accumbens

7

Drugs work by doing one or more of the following to neurotransmitters:

1. Increasing the synthesis.
2. Causing vesicles to leak.
3. Increasing release.
4. Decreasing reuptake.
5. Blocking the breakdown into inactive chemical.
6. Directly stimulating or blocking postsynaptic receptors

8

Stimulant Drugs

1. increase excitement, alertness, motor activity and elevate mood.
2. Examples: amphetamines, cocaine, methylphenidate (Ritalin), MDMA (Ecstasy), nicotine, caffeine

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How Amphetamines Work

stimulate dopamine synapses by increasing the release of dopamine from the presynaptic terminal

10

How Cocaine works

blocks the reuptake of dopamine, norepinephrine, and serotonin

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How Methylphenidate (ritalin) works

also blocks the reuptake of dopamine but in a more gradual and more controlled rate.

12

How MDMA works

1. increases the release of dopamine at low doses that account for its stimulant properties.
2. Increases the release of serotonin at higher doses accounting for its hallucinogenic properties.
3. Research indicates damage to neurons that contain serotonin.
4. Degree of risk to humans is not clear.

13

How Nicotine Works

1. active ingredient in tobacco.
2. Nicotine stimulates one type of acetylcholine receptor known as the nicotinic receptor.
3. Nicotinic receptors are found in the central nervous system, the nerve-muscle junction of skeletal muscles and in the nucleus accumbens.

14

How Opiates work

decrease sensitivity to pain and increase relaxation by attaching to endorphin receptors in the brain.
Examples: morphine, heroin, methadone

15

How THC works

1. active ingredient in marijuana.
2. THC attaches to cannabinoid receptors throughout the brain but especially the cerebral cortex, cerebellum, basal ganglia, and hippocampus.

3. Anandamide and 2-AG are the endogenous chemicals that attach to these receptors naturally.receptors.

16

Hallucinogenic drugs work by

1. cause distorted perception.
2. Many hallucinogenic drugs resemble serotonin in their molecular shape.
3. Hallucinogenic drugs stimulate serotonin type 2A receptors (5-HT2A) at inappropriate times or for longer duration than usual thus causing their subjective effect

17

Alcohol has a number of diverse physiological effects including

1. Inhibition of sodium across the membrane.
2. Expansion of the surface of membranes.
3. Decreased serotonin activity.
4. Enhanced response by the GABA(A) receptor.
5. Blockage of glutamate receptors.
6. Increased dopamine activity.

18

Bath Salts

1. Have effects similar to cocaine and methamphetamine.
2. Very little is known about how bath salts interact with the brain and how they are metabolized by the body.
3. They are similar to amphetamines in that they cause stimulant effects by increasing the concentration of monoamines such as dopamine, serotonin, and norepinephrine in synapses. They are generally less able to cross the blood brain barrier than amphetamines

19

Proliferation

1. Proliferation refers to the production of new cells/neurons in the brain primarily occurring early in life.

2. Early in development, the cells lining the ventricles divide.
3. Some cells become stem cells that continue to divide.
4. Others remain where they are or become neurons or glia that migrate to other locations.

20

Migration

1. Migration refers to the movement of the newly formed neurons and glia to their eventual locations.

2. Some don’t reach their destinations until adulthood.
3. Occurs in a variety of directions throughout the brain

21

Differentiation

1. Differentiation refers to the forming of the axon and dendrite that gives the neuron its distinctive shape.

2. The axon grows first either during migration or once it has reached its target and is followed by the development of the dendrites.

22

Myelination

1. Myelination refers to process by which glia produce the fatty sheath that covers the axons of some neurons

2. Myelin speeds up the transmission of neural impulses.
3. First occurs in the spinal cord and then in the hindbrain, midbrain and forebrain.
4. Occurs gradually for decades

23

Synaptogenesis

1. Synaptogenesis is the final stage of neural development and refers to the formation of the synapses between neurons

2. Occurs throughout the life as neurons are constantly forming new connections and discarding old ones
3. Slows significantly later in the lifetime

24

Development of neuron stages

1. Proliferation
2. Migration
3. Differentiation
4. Myelination
5. Synaptogenesis

25

Axon Pathfinding

1. Axons must travel great distances across the brain to form the correct connections.

2. Sperry’s (1954) research with newts indicated that axons follow a chemical trial to reach their appropriate target.

3. Growing axons reach their target area by following a gradient of chemicals in which they are attracted by some chemicals and repelled by others

26

Types of Stroke

1. Ischemia: the most common type of stroke, resulting from a blood clot or obstruction of an artery
Neurons lose their oxygen and glucose supply

2. Hemorrhage: a less frequent type of stroke resulting from a ruptured artery
Neurons are flooded with excess blood, calcium, oxygen, and other chemicals

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strokes cause:

1. Edema: the accumulation of fluid in the brain resulting in increased pressure on the brain and increasing the probability of further strokes.

2. Disruption of the sodium-potassium pump leading to the accumulation of potassium ions inside neurons.

28

Recovery after head trauma

1. Destroyed cell bodies cannot be replaced, but damaged axons do grow back under certain circumstances.

If an axon in the peripheral nervous system is crushed, it follows its myelin sheath back to the target and grows back toward the periphery at a rate of about 1 mm per day
2. Damaged axons in CNS only regenerate one to two millimeters in mature mammals
3. Paralysis caused by spinal cord damage is relatively permanent.
4. Scar tissue makes a mechanical barrier to axon growth.
5. Glia cells reacting to damage in CNS release chemicals that inhibit axon growth.

29

Nervous system structure

CNS & PNS
Somatic (sensory/motor) & Autonomic (organ reg)
Symp (fight/flight) & Parasymp (relax)

30

Effects of Sympathetic NS

1. increases heart rate, blood pressure, respiration, etc. (“fight or flight” response).
2. comprised of ganglia on the left and right of the spinal cord.
3. mainly uses norepinephrine (NE) as a neurotransmitter at the postganglionic synapses.

31

Postganglionic Axons

release acetylcholine as neurotransmitter

32

Bell-Magendie Law

entering dorsal roots carry sensory information and the exiting ventral roots carry motor information

33

Hindbrain consists of

1. Medulla.
2. Pons.
3. Cerebellum

34

hemispheres connected by

two bundles of axons called the corpus callosum and the anterior commissure

35

Organization of CC

1. The CC is approximately 2-4mm in thickness.
2. Contains up to six distinct laminae (layers) that are parallel to the surface of the cortex.
3. Cells of the cortex are also divided into columns that lie perpendicular to the laminae.
4. Divided into four main lobes: occipital, parietal, temporal, and frontal.

36

Occipital Lobe

1. A very large cortical area in the back of the brain.
2. Located at the posterior (caudal) end of the cortex.
3. Also known as the striate cortex or the primary visual cortex.
4. Damage can result in cortical blindness.
(i.e. damage to the left side of the OC will result in visual deficits to the observers right visual field.

37

Parietal Lobe

1. Contains the postcentral gyrus (aka “primary somatosensory cortex”) which is the primary target for touch sensations, information from muscle receptors, and joint receptors.
2. Also responsible for processing and integrating information about eye, head and body positions from information sent from muscles and joints.

38

Granular Neurons

1. The innermost layer of the cortex and are characterized by a small soma, an extremely narrow axon, a short stubby claw looking set of 3-4 dendrites.
2. GN are the only known neuron types that regenerate in adulthood. (Dentate gyrus of the hippocampus)

39

Pyramidal Neurons

1. are found in: the cerebral cortex, the hippocampus, and amygdala.
2. Were discovered by Cajal.
3. Primary excitation cells of the corticospinal tract (aka pyramidal tract)
4. Triangular Shaped Soma (this is how it got it’s name)
5. Many Dendritic Spines
6. Many Dendritic Spines
7. 30,000 excitatory synapses
1700 inhibitory synapses

40

Temporal Lobe

1. Located on the lateral portion of each hemisphere near the temples.
2. Target for auditory information and essential for processing spoken language.
3. Also responsible for complex aspects of vision including movement and some emotional and motivational behaviors
4. Stimulation of the temporal lobe causes “spiritual” and “supernatural” like experiences and feelings

41

Kluver Bucy Syndrome

(failure to display normal fears and anxietites) associated with temporal lobe damage.

42

Frontal Lobe Features

1. Motor Cortex
2. Prefrontal Cortex
3. Precentral Gyrus

43

Precentral Gyrus

primary motor cortex and is responsible for the control of fine motor movement

44

Prefrontal Cortex

1. the integration center for all sensory information and other areas of the cortex. (most anterior portion of the frontal lobe)
2. Responsible for higher functions such as abstract thinking and planning.
3. Responsible for our ability to remember recent events and information (working memory).
4. Allows for regulation of impulsive behaviors and the control of more complex behaviors

45

Binding Problem

how the visual, auditory, and other areas of the brain produce a perception of a single object

46

Lobotomies

1. Prefontal Lobotomy: surgical disconnection of the prefrontal cortex from the rest of the brain.
2. In the 1940’s and 50’s roughly 40,000 were performed in U.S.
3. Many were carried out by Dr. Walter Freeman who was not a surgeon.
4. Freeman used crude instrumentation, like ice picks and electric drills.
5. Called his call the “lobotomobile”.
6. Lobotomy victims suffered from inabilities to plan, distrctability, memory problems, impulsivity, and social problems.

47

Broadmann Areas

A Brodmann area is a region in the brain cortex defined in many different species based on its cytoarchitecture.

Cytoarchitecture is the organization of the
cortex as observed when a tissue is stained for nerve cells.

Brodmann areas were originally defined by Korbinian Brodmann and referred to by numbers from 1 to 52. Some of the original areas have been subdivided further
and referred to, e.g., as "23a" and "23b".

So, BA are categorized by the areas structure and function.

48

causes of brain damage

tumors
infections
toxins
degenerative diseases
closed head injury