Biology and behavior

Question 1

Which parts make up the nervous system?

Answer 1

the central nervous and peripheral nervous system

Question 2

Which nervous system houses the brain and spinal cord?

Answer 2

the central nervous system

Question 3

The somatic nervous system and autonomic nervous system are part of which nervous system?

Answer 3

the peripheral nervous system

Question 4

Describe how the central nervous system and peripheral nervous system communicate.

Answer 4

The peripheral nervous system (PNS) sends a variety of information to the central nervous system (CNS). The CNS organizes and evaluates that information, then directs the PNS to perform specific behaviors or make bodily adjustments.

Question 5

describe the way neurons communicate

Answer 5

Neurons communicate through a combination of electrical and chemical signals. The process can be broken down as follows:

Dendrites receive chemical signals from other neurons.
These signals are processed in the cell body (Soma).
The processed information travels down the axon as an electrical signal called an action potential.
At the end of the axon, the signal reaches the terminal buttons, where it triggers the release of neurotransmitters into the synapse (the space between neurons).
The neurotransmitters cross the synapse and bind to receptors on the postsynaptic neuron, causing a response in the receiving neuron.
The action potential is an essential part of this communication, as it allows the electrical signal to travel along the neuron. The signal is influenced by excitatory or inhibitory inputs, which determine whether or not the neuron will fire and pass on the information.

Question 6

what is the resting membrane potential?

Answer 6

The resting membrane potential is the electrical charge difference between the inside and outside of a neuron when it is not actively firing. Typically, the inside of the neuron is more negatively charged than the outside, with a resting potential of about -70 millivolts.

This charge difference occurs because there are more negative ions inside the neuron compared to the outside. The resting membrane potential is maintained by ion channels, which regulate the flow of ions, particularly sodium (Na⁺) and potassium (K⁺) ions. The neuron’s resting state is described as being polarized, meaning it is prepared for action potential firing when stimulated.

Question 7

what are myelin sheath, and describe the function of them.

Answer 7

The myelin sheath is a fatty layer that encases and insulates the axons of many neurons, similar to how plastic insulation surrounds electrical wires. The myelin sheath is made up of glial cells and is segmented, with small gaps called the Nodes of Ranvier between the segments.

The function of the myelin sheath is to:

Increase the speed of the action potential: By insulating the axon, it allows the electrical signal to jump between the Nodes of Ranvier in a process called saltatory conduction, which speeds up the transmission of the signal along the axon.
Insulate and protect the axon: It prevents the electrical signals from dissipating as they travel down the axon, ensuring efficient communication between neurons.

Question 8

Can a neuron fire at -59millivolts? Explain your answer.

Answer 8

no, the action potential only activates one the threshold of around -55MV has been surpassed.

Question 9

define the absolute refractory period.

Answer 9

The absolute refractory period is the brief time after a neuron has fired an action potential during which it is completely unable to fire again, no matter how strong the incoming stimulus is.

During this period, the sodium ion channels that were opened during the action potential become inactivated and cannot reopen until the neuron returns to its resting state. This ensures that action potentials only move in one direction along the axon and that neurons have time to reset before firing again.

Question 10

what does the neurotransmitter Acetylcholine do?

Answer 10

Motor control over muscles: It is responsible for signaling muscles to contract, which is crucial for movement.
Learning and memory: Acetylcholine is involved in cognitive functions like learning and memory, particularly in the brain’s hippocampus.
Sleeping and dreaming: It also plays a role in regulating sleep cycles, including REM (rapid eye movement) sleep, which is associated with dreaming.

Question 11

what does the neurotransmitter Norepinephrine do?

Answer 11

Arousal: It increases alertness and wakefulness, helping the brain stay vigilant and attentive.
Vigilance: It prepares the body to respond to stressful or dangerous situations, often referred to as the “fight or flight” response.
Attention: Norepinephrine helps enhance focus and concentration by regulating attention levels, particularly in demanding or challenging situations.

Question 12

what does the neurotransmitter Serotonin do?

Answer 12

Emotional states: It plays a major role in regulating mood and is associated with feelings of well-being and happiness. Low levels of serotonin are linked to depression and anxiety.
Impulsiveness: Serotonin helps modulate impulsive behavior, helping with emotional control and decision-making.
Dreaming: It also plays a role in regulating sleep cycles, particularly influencing dreams during REM (rapid eye movement) sleep.

Question 13

what does the neurotransmitter Dopamine do?

Answer 13

Reward and motivation: Dopamine plays a key role in the brain’s reward system, reinforcing behaviors by creating feelings of pleasure, which motivates individuals to repeat those behaviors.
Motor control: It is essential for controlling voluntary movements, and dysfunction in dopamine levels is linked to motor disorders like Parkinson’s disease.
Cognitive functions: Dopamine also influences attention, learning, and decision-making by reinforcing rewarding behaviors.

Question 14

what does the neurotransmitter GABA (gamma-aminobutyric acid) do?

Answer 14

Inhibition of action potentials: GABA reduces the likelihood that a neuron will fire, serving as the brain’s primary inhibitory neurotransmitter.
Anxiety reduction: By inhibiting neural activity, GABA helps calm the nervous system and plays a major role in reducing anxiety and stress.
Regulation of muscle tone: GABA also helps regulate muscle tone by preventing excessive neuronal firing that can lead to muscle spasms.

Question 15

which neurotransmitter is crucial for the enhancement of action potentials, and is active in learning and memory?

Answer 15

Glutamate

Question 16

Which neurotransmitter is responsible for pain reduction and is involved in reward mechanisms?

Answer 16

Endorphins

Question 17

what are receptors?

Answer 17

Receptors are specialized protein molecules located on the postsynaptic membrane of neurons. They respond to specific neurotransmitters released into the synapse. When a neurotransmitter binds to its corresponding receptor, it triggers a response in the postsynaptic neuron, either exciting or inhibiting its activity, depending on the type of neurotransmitter and receptor involved.

Question 18

explain and name the three major termination events, that terminate the neurotransmitters influence.

Answer 18

Reuptake: The neurotransmitter is taken back into the presynaptic neuron’s terminal buttons, stopping its activity in the synapse. This process recycles the neurotransmitter for future use.

Enzyme deactivation: An enzyme breaks down the neurotransmitter in the synapse, rendering it inactive and preventing further interaction with receptors.

Autoreception: Some neurotransmitters bind to autoreceptors on the presynaptic neuron, which monitor the amount of neurotransmitter released. When too much is detected, the autoreceptors signal the presynaptic neuron to stop releasing more neurotransmitter.

Question 19

what are agonists? Explain how they influence neurotransmission.

Answer 19

are substances or drugs that enhance or mimic the activity of a neurotransmitter in the brain. They can influence neurotransmission in several ways:

Increase neurotransmitter production: Agonists can increase the amount of neurotransmitter produced, resulting in more being available for release into the synapse.

Block reuptake: Some agonists prevent the reuptake of neurotransmitters, allowing them to remain active in the synapse for a longer period.

Mimic neurotransmitters: Agonists can directly bind to the postsynaptic receptors, activating them as if they were the natural neurotransmitter, thereby increasing the effect of that neurotransmitter.

Question 20

what are antagonists? Explain how they influence neurotransmission.

Answer 20

are substances or drugs that inhibit or block the activity of a neurotransmitter in the brain. They can influence neurotransmission in several ways:

Decrease neurotransmitter production: Antagonists can reduce the amount of neurotransmitter produced, resulting in less being available for release into the synapse.

Destroy neurotransmitters in the synapse: Some antagonists promote the destruction or breakdown of neurotransmitters in the synapse, reducing their availability to bind to receptors.

Block receptors: Antagonists can bind to postsynaptic receptors without activating them, effectively blocking the natural neurotransmitter from binding and exerting its effect.

Question 21

give 3 examples of agonists.

Answer 21

Morphine: Mimics the action of endorphins by binding to opioid receptors, reducing pain and producing a feeling of euphoria.

Nicotine: Acts as an agonist for acetylcholine by binding to its receptors, enhancing arousal and attention.

Selective Serotonin Reuptake Inhibitors (SSRIs): Increase the availability of serotonin by blocking its reuptake, thereby enhancing mood and reducing symptoms of depression.

Question 22

give 3 examples of antagonists.

Answer 22

Naloxone: Acts as an opioid receptor antagonist, blocking the effects of opioid drugs like morphine or heroin, and is often used to reverse opioid overdoses.

Beta-blockers (e.g., Propranolol): Block the effects of norepinephrine on beta-adrenergic receptors, helping reduce blood pressure and anxiety.

Haloperidol: An antagonist for dopamine receptors, used to treat schizophrenia by blocking dopamine activity and reducing hallucinations and delusions.

Question 23

Describe the structure of a neuron and explain how signals travel through it.

Answer 23

A neuron is composed of several key parts:

Dendrites: These branch-like extensions receive chemical signals from other neurons.
Cell Body (Soma): The soma processes the information received from the dendrites.
Axon: Once processed, the information is transmitted electrically along the axon.
Terminal Buttons: At the end of the axon, the signal reaches the terminal buttons, where it triggers the release of neurotransmitters.
Synapse: The neurotransmitters cross the synapse (the gap between neurons) and bind to receptors on the postsynaptic neuron, continuing the communication process.
Signals travel from dendrites to the soma, then down the axon, and finally to the terminal buttons, where chemical communication with the next neuron begins across the synapse.