1PSY 101 – Dr. V

Chapter 2 Lecture Notes

Module 4 – Neural and Hormonal Systems

Overview of Nervous System

• Nervous System - _____________________________________________________________________________________________________________________________________________

• Neuroscience – deals with the structure and function of the brain and the neurons, nerves, and nervous tissue that form the nervous system.

• Relationship to behavior and learning.

Structure of the Neuron

• Neurons - ____________________________________________________________________________________________________________________________________________________

• Parts of a Neuron

• _________________ - branch-like structures that receive messages from other neurons.

• __________ - the cell body of the neuron, responsible for maintaining the life of the cell.

• _________ - long tube-like structure that carries the neural message to other cells.

Other Types of Brain Cells

• Glial cells - grey fatty cells that:

• ________________________________________________________________________

• ________________________________________________________________________

• produce myelin to coat axons,

• Myelin Sheath - ______________________________________________________________________________________________________________________________________________________________________________________

• Generated by a Schwann Cell

• clean up waste products and dead neurons.

• Note: Neurons only makeup 10% of cells in the brain; the remaining 90% is glial

Neurons in the Body

• Nerves – _______________________________________________________________________

• Neurilemma – Schwann’s membrane.

• __________________________________________________________________________________________________________________________________

• Most axons of the neurons in the brain and spinal cord do not usually have this coating, thus, more likely to be permanently damaged.

2PSY 101 – Dr. V

• _______________________ – disease that damages the myelin sheath (i.e., demyelination), which leads to a loss of function in those damaged cells.

Neuron

Generating the Message: Neural Impulse

• Ions – charged particles.

• Inside neuron – __________________________

• Outside neuron – ___________________________

• Resting potential – the state of the neuron when not firing a neural impulse.

• ________________ – Each neuron receives excitatory and inhibitory signals from many neurons. When the excitatory signals minus the inhibitory signals exceed a minimum intensity (threshold) the neuron fires an action potential

• _______________________ - the release of the neural impulse consisting of a reversal of the electrical charge within the axon.

• Allows positive sodium ions to enter the cell.

• All-or-none – _________________________________________________________________________________________________________________________________________________

• Difference between strong stimulation and weak stimulation? – strong message results in the neuron firing more quickly, and it will also cause more neurons to fire.

• ________________________ – neuron is incapable of repeating (i.e., firing) until returns to resting potential (very brief – often milliseconds)

• Return to resting potential.

3PSY 101 – Dr. V

Action Potential

Sending the Message to Other Cells

• Axon terminals - branches at the end of the axon.

• Synaptic knob (or terminal button) – rounded areas on the end of axon terminals.

• Synaptic vesicles - __________________________________________________

_________________________________________________________________

• ___________________________- chemical found in the synaptic vesicles which, when released, has an effect on the next cell.

• Synapse/synaptic gap - microscopic fluid-filled space between the rounded areas on the end of the axon terminals of one cell and the dendrites or surface of the next cell.

• _____________________ - holes in the surface of the dendrites or certain cells of the muscles and glands, which are shaped to fit only certain neurotransmitters.

4PSY 101 – Dr. V

Cleaning up the Synapse

• ______________ - process by which neurotransmitters are taken back into the synaptic vesicles; applies the “breaks” on neurotransmitter action.

• Enzyme - a complex protein that is manufactured by cells.

• e.g., one type specifically breaks up acetylcholine because muscle activity needs to happen rapidly, so reuptake would be too slow.

How Neurotransmitters Influence Us

Serotonin pathways are involved with _______________________________________________

_____________ pathways are involved with diseases such as schizophrenia and Parkinson’s disease.

________________ – produce good feelings (e.g., “runner’s high”)

o explains painkilling effects of acupuncture

o explains indifference to pain when severely injured

o opiates ______________ _____________

when flooded with opiate drugs, the brain stops producing own natural opiates

when drug is withdrawn, deprivation of opiates causes great discomfort (i.e., withdrawal)

5PSY 101 – Dr. V

Neuron Communication

• Neurons must be turned ON and OFF.

• Excitatory neurotransmitter - neurotransmitter that causes the receiving cell ________

• Inhibitory neurotransmitter - neurotransmitter that causes the receiving cell ___________

• Chemical substances can affect neuronal communication: Agonists & Antagonists

Lock & Key Mechanism – neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism.

o Agonist – ________________________________________________________________

Some opiate drugs amplify normal sensations of arousal and pleasure (i.e., “high”)

Black widow spider venom – _____________________________________ = violent muscle contractions, convulsions, possible death

o Antagonist – _____________________________________________________________

________ – causes paralysis by blocking ACh release; can come from improperly canned food

__________________ – smoothes wrinkles by paralyzing the underlying facial muscles

Some antagonists will occupy receptor sites and block its effect; similar to the natural neurotransmitter, but not similar enough to stimulate the receptor

__________ – a poison that can be applied to hunting-dart tips

o Occupies and blocks ACh receptor sites, which does not allow the neurotransmitter to affect the muscles = paralysis

6PSY 101 – Dr. V

The Nervous System

Central Nervous System

• Central nervous system (CNS) - __________________________________________________________________________________________________________________________________

• Spinal cord - a long bundle of neurons that carries messages to and from the body to the brain that is responsible for very fast, lifesaving reflexes.

The Reflex Arc: Three Types of Neurons

• Sensory neuron - ______________________________________________________________________________________________________________________________________________

• Also called _____________________

• Motor neuron - _______________________________________________________________________________________________________________________________________________

• Also called _____________________

• __________________ - a neuron found in the center of the spinal cord that receives information from the sensory neurons and sends commands to the muscles through the motor neurons.

• This _________________ skips going to the brain – like a shortcut

• Interneurons also make up the bulk of the neurons in the brain.

7PSY 101 – Dr. V

The Spinal Cord & Reflexes

Peripheral Nervous System

• Peripheral nervous system (PNS) - ______________________________________________________________________________________________________________________________________________________________________________________________________________

• Somatic nervous system

• Autonomic nervous system

Somatic Nervous System

• Soma = body.

• Somatic nervous system - ________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

• Sensory pathway - nerves coming from the sensory organs to the CNS consisting of sensory neurons.

• Motor pathway - nerves coming from the CNS to the voluntary muscles, consisting of motor neurons – i.e., skeletal muscles

Autonomic Nervous System

• Autonomic nervous system (ANS) - division of the PNS consisting of nerves that control all of the ______________________ muscles, organs, and glands sensory pathway nerves coming from the sensory organs to the CNS consisting of sensory neurons.

• ____________________________________________ - part of the ANS that is responsible for reacting to stressful events and bodily arousal.

• ____________________________________________ - part of the ANS that restores the body to normal functioning after arousal and is responsible for the day-to-day functioning of the organs and glands.

8PSY 101 – Dr. V

The Endocrine Glands

• Endocrine glands - glands that secrete chemicals called hormones directly into the bloodstream.

• Hormones - chemicals released into the bloodstream by endocrine glands.

• _____________________ - gland located in the brain that secretes human growth hormone and influences all other hormone-secreting glands (also known as the ______________________).

• Remember: influenced by the hypothalamus

• Pineal gland - endocrine gland located near the base of the cerebrum that secretes melatonin, which regulates _________________________________________________________________

• Thyroid gland - endocrine gland found in the neck that secretes thyroxin, which regulates ______________________________________________________________________________

• ______________- endocrine gland that controls the levels of sugar in the blood by secreting insulin and glucagons.

• Too little insulin = _________________

• Too much insulin = ____________________ (low blood sugar) – feel hungry all the time

• Gonads - the sex glands that secrete hormones that regulate sexual development and behavior as well as reproduction.

• Ovaries - the female gonads.

• Testes - the male gonads.

• ______________________ - endocrine glands located on top of each kidney that secrete over 30 different hormones to deal with stress, regulate salt intake, and provide a secondary source of sex hormones affecting the sexual changes that occur during adolescence.

• _______________ – one of the most “important” adrenal hormones

• Released when the body experiences __________________________________