1.2 & 1.3 - Unit 1 Biological Bases of Behavior

1.2-1 The Nervous System

1. Explain the following terms:

   • Nervous System: the body’s 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: sensory and motor neurons that connect the central nervous system to the rest of the body

   • Nerves: bundled axons that form neural cables connecting the central nervous system with muscles, glands, and sensory organs

   • Sensory (Afferent) Neurons: neurons that carry incoming information from the body’s tissues and sensory receptors to the brain and spinal cord

   • Motor (Efferent) Neurons: neurons that carry outgoing information from the brain and spinal cord to the muscles and glands

   • Interneurons: neurons within the brain and spinal cord, they communicate internally and process information between the sensory inputs and motor outputs

2. Explain how the two components of the peripheral nervous system work.

   • Somatic nervous system: enables voluntary control of the skeletal muscles

   • Autonomic nervous system: controls our glands and organs

3. Identify and explain the two important functions of the subdivisions of the autonomic nervous system.

   • Sympathetic (arousing): mobilizes energy, “flight or fight” (arouses and expends energy, accelerates heart rate, raises blood pressure, slows digestion, raises blood sugar, cools with sweat)

   • Parasympathetic (calming): conserves energy as it calms the body

4. The two parts of the autonomic nervous system work together to maintain what?

   • homeostasis

5. The brain’s individual neurons work together to form what?

   • Neural networks

6. What is the second part of the central nervous system and what is the function of this part?

   • Spinal cord, connects peripheral nervous system and the brain (ascending fibers send sensory info up and descending diners send back motor control)

7. Explain:

   • Reflexes: simple automatic response to a sensory stimulus, such as the knee-jerk response

   • Reflex Arc: single sensory neuron and single motor neuron, communicates through a spinal cord interneuron

8. Another neural circuit enables what? Pain reflex

Module 1.3a The Neuron and Neural Firing: Neural Communication and the Endocrine System

Module 1.3-1 Neurons

1. Explain each of the following terms:

   • Neurons: nerve cell, the basic building block of the nervous system

   • Cell Body: the part of a neuron that contains the nucleus

   • Dendrites: branching extensions that receive and integrate messages, conducts impulses toward the cell body

   • Axon: the segmented neuron extension that passes messages through its branches to other neurons or to muscles or glands

   • Myelin Sheath: fatty tissue layer segmentally encasing the axons of some neurons, enables vastly greater transmission speed as neural impulses hop from one node to the next

   • Glial Cells: cells in the nervous system that support, nourish, and protect neurons, they might also play a role in learning, thinking, and memory

   • Action Potential: neural impulse, brief electrical charge that travels down an axon

   • Nucleus: a spherical or oval-shaped structure that contains the cell's genetic material and controls the production of proteins, cell growth, and differentiation

     

2. Identify the chemical state that exists when a neuron is in “resting potential”.

   • positive ions outside, negative ions inside

3. Explain how depolarization occurs.

   • when a neuron fires the axon opens and ions flow in, this happens repeatedly from axon to axon

4. The temporary flow of positive ions creates what?

   • The neural impulse or action potential

5. Describe the difference between excitatory and inhibitory neurons.

   • Excitatory: signals push neurons to act

   • Inhibitory: signals push a neuron to remain in the resting state

6. Explain the following terms:

   • Threshold: level of stimulation required to trigger a neural impulse, excitatory is greater than inhibitory

   • Refractory Period: a brief resting pause that occurs after a neuron has fired, subsequent action potentials cannot occur until the axon return to its resting state

   • All-or-None Response: a neuron’s reaction of either firing (with a full-strength response) or not firing

1.3-2 How Neurons Communicate

7. Explain what a synapse and a neurotransmitter are and how they work together. (Use the chart on p. 31 in the textbook to help answer the 2nd part of the question.)

   • Synapse: space between axon tip of sending neuron and dendrite of receiving neuron

   • Neurotransmitters: chemical messengers that cross the synapses between neurons

   1. Electrical impulse travels down an axon until reaching the synapse

   2. When the action potential reaches the axon terminal, it stimulates the release of transmitter molecules, these molecules cross the synaptic gap and bind to the receptor sites on the receiving neuron, this allows electrically charged atoms to enter the receiving neuron and excite or inhibit a new action potential

   3. Excess neurotransmitters are reabsorbed (a process called reuptake), drift away, or are broken down by enzymes

1.3-3 How Neurotransmitters Influence Us

8. Fill in the chart using p. 33 from the textbook.

9. Explain how an agonist and an antagonist affect neurotransmitters.

   • Agonist: increases a neurotransmitter’s action

   • Antagonist: inhibits or blocks a neurotransmitter’s action

1.3-4 The Endocrine System

10. Explain how the endocrine system works.

    • a set of glands and fat tissue that secrete hormones into the bloodstream

11. What are hormones?

    • Chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues

12. Explain the “feedback system” that connects the nervous system and the endocrine system.

    • Brain -> pituitary -> other glands -> hormones -> body and brain

    • Pituitary: in brain, controlled by hypothalamus; growth hormones; directs other glands to release hormones

Module 1.3b The Neuron and Neural Firing: Substance Use and Psychoactive Drugs

Module 1.3-5 Tolerance 

13. What is a psychoactive drug?

    • A chemical substance that alters the brain, causes changes in perceptions and moods

14. Use the chart on p. 40 to answer the following:

    1. Diminished Control (2 common ways to get there: recreational, prescription)

       1. Uses more substance, or for longer than intended

       2. Tries unsuccessfully to regulate the use of substance

       3. Spends much time acquiring, using, or recovering from the effects of substance

       4. Craves the substance

    2. Diminished Social Functioning

       1. Use disrupts commitments at work, school, or home

       2. Continues use despite social problems

       3. Causes reduced social, recreational, and work activities

    3. Hazardous use

       1. Continues use despite hazards

       2. Continues use despite worsening physical or psychological problems

    4. Drug Action

       1. Experiences tolerance (needing more substance for the desired effect)

       2. Experiences withdrawal (unpleasant mental or physical reactions) when attempting to end use

1.3-6 Depressants

15. What are depressants?

    • Drugs that reduce neural activity and slow body functions

16. Explain why alcohol is a depressant.

    • slows brain activity that controls judgement and inhibitions, it is a disinhibitor

17. Describe how alcohol is an “equal-opportunity drug”.

    • Increases (disinhibits) helpful tendencies

    • Increases harmful tendencies

18. Explain the following terms:

    • Tolerance: needing more substance for the desired effect

    • Addiction: everyday term for compulsive substance abuse (and sometimes for dysfunctional behavior patterns, such as out-of-control gambling) that continues despite harmful consequences

    • Withdrawal: discomfort and distress that follow discontinuing an addictive drug or behavior

19. Identify and explain the four ways that alcohol can impact mentally.

    • Slowed neural processing: causes reactions to slow, speech to sur, and skilled performance to deteriorate, lower inhibitions

    • Memory disruption: can cause blackouts and interrupt REM sleep

    • Reduced self-awareness: mind wanders and you are not aware that you zoned out, focuses on attention on an immediate arousing citation and distracts it from normal inhibitions and future consequences

    • Expectancy effects: expectation influence behavior

20. What are barbiturates?

    • Drugs that depress central nervous system activity, reducing anxiety but impairing memory and judgement

21. What harm can barbiturates in large doses cause?

    • Impairs memory and judgement

22. What are opioids?

    • Opium and its derivatives, they depress neural activity, temporarily lessening pain and anxiety

23. If opioid use is large term, what can happen to the brain?

    • The brain can stop producing endorphins

1.3-7 Stimulants

24. What are stimulants?

    • Drugs that excite neural activity and speed up body function

25. How do stimulants affect us physically and psychologically?

    • Pupils dilate, heart and breathing rates increase, blood sugar levels rise, reduced appetite, energy and self confidence rise

26. How long does it take for nature to change you if you smoke?

    • 12 minutes

27. Use the figure on p. 47 to explain the effects of nicotine.

    • Arouses brain to state of increased alertness

    • Increases heart rate and blood pressure

    • At high levels, relaxes muscles and triggers the release of neurotransmitters that may reduce stress

    • Reduces circulation to extremities

    • Suppresses appetite for carbohydrates

28. How does cocaine impact our brain?

    • Produces a rush of euphoria that depletes the brain’s supply of the neurotransmitter dopamine, serotonin, and norepinephrine

29. Amphetamines (Methamphetamine) impacts the brain in what way?

    • Prolonged use can have what impact on the user? It stimulates neural activity, prolonged use can reduce baseline dopamine levels which leaves the user with depressed functioning

30. Ecstasy or MDMA can be both a stimulant and a mild hallucinogen.

31. Long term use of MDMA can have what impacts on the user?

    • Suppresses the immune system

    • Impairs memory

    • Slows though

    • Disrupts sleep by interfering with serotonin’s control of the circadian rhythm

Damages serotonin-producing neurons (makes you depressed)

1.3-8 Hallucinogens

32. Describe hallucinogens.

    • Psychedelic drugs that distort perceptions and evoke sensory images in the absence of sensory input

33. How can hallucinogens lead to “near-death experiences”?

    • people feel separated fromtheir body and experience dreamlike scenes, sense of self dissolves and so does the border between themselves and the external world

34. LSD users can experience a “trip” that ranges from euphoria to detachment to panic.

35. Identify the findings from the study done by the U.S. National Academies of sciences, Engineering, and Medicine that pertain to marijuana.

    • Alleviates chronic pain, chemotherapy-related nausea, and muscle soreness among people with multiple sclerosis

    • May offer short-term sleep improvements

    • Doesn’t increase risk for tobacco-related diseases such as lung cancer

    • Predicts increased risk of traffic accidents, chronic bronchitis, psychosis, social anxiety disorder, suicidal thoughts

    • Likely contributes to impaired attention, learning, and memory, and possibly to academic underachievement