Week 5

Question 1

What is a neuron?

Answer 1

Neurons are the basic cellular units of the nervous system and are basically electrochemical information storage and transmission devices.

Question 2

What are the types of neurons?

Answer 2

Unipolar, bipolar and multipolar

Unipolar- Relay information forward; 1 axon and no dendrites

Bipolar- Sensory perceptions; 1 axon and 1 dendrite

Question 3

Multipolar-

Answer 3

Communicate with other neurons; 1 axon and many dendrites

Question 4

What is the function of the glial cells?

Answer 4

Glial cells help with the ‘menial’ tasks of cleaning up waste products, providing nutrients and physical support, and guiding developing neurons to their proper places.

Question 5

What are the parts of neurons?

Answer 5

Dendrites (receive information), cell body or soma (process information and contains the nucleus) and the axon/terminal button (sends information)

Question 6

Describe the process of dendrites

Answer 6

Dendrites maximize branching out to receive input: chemical signals enter the dendrites spines, then travel down to the cell body where they are averaged to one of two simple conclusions- fire an action potential or don’t fire an action potential.

Question 7

What happens when the signal of dendrites is fire?

Answer 7

If the signal is fired, then that signal runs down the axon- all or nothing signal.

Question 8

Dendrites

Answer 8

receivers

Question 9

Axon terminals

Answer 9

transmitters

Question 10

Schwann’s cells

Answer 10

type of glial cell (they make the myelin)

Question 11

Axon

Answer 11

The conducting fiber

Question 12

Myelin sheath

Answer 12

insulating fatty layer that speeds transmission

Question 13

Sensory neuron

Answer 13

activated by information inputted from the environment

Question 14

Motor neuron

Answer 14

transmit impulses from the spinal cord to the skeletal and smooth muscles

Question 15

Interneuron

Answer 15

allows for sensory neurons and motor neurons to communicate with the CNS (central nervous system)

Question 16

Neurotransmitter

Answer 16

is triggered at the end of the axon that travels across the synapses.

Question 17

What are the principles that help drive the action potential?

Answer 17

Electrical gradient (difference in charge) and a concentration gradient (difference in concentration)

Question 18

Anions

Answer 18

negatively charged ions

Question 19

Cations

Answer 19

positively charged ions

Question 20

Electrostatic pressure

Answer 20

The repelling force of 2 ions or attractive force

Question 21

Diffusion

Answer 21

movement of molecules from high concentration to low concentration

Question 22

What are the 3 important molecules?

Answer 22

Sodium, chlorine and potassium

Question 23

What drives the action potential?

Answer 23

1.At rest, there is a greater concentration of Na outside the neuron and a greater concentration of K inside the neuron; however, there is relatively more Na out than K in.

2. This leads to a difference in concentration and in electrical potential across the impermeable membrane; this leads to a difference called the resting potential.

3.Na gates are voltage-sensitive, that is they require a sufficient resting voltage to be opened. If and only if, a sufficient increase in voltage is inputted from the dendrites, depolarization will occur: Na channels open and Na rushes into the neuron, making the neuron much more positive (depolarization phase).

4.Slightly later, K gates open and allow K to leave the neuron.

5.At the peak of the action potential, the flow of Na in is equal to the flow of K out.

6.The flow of Na slows down, while K out continues, repolarizing and making the neuron less positive- meaning it is hyperpolarized, refractory period and nerve cannot fire again right away.

7.A Na/K pump then removes Na and imports K to restore the resting potential. This pump uses ATP (molecular energy), and in total accounts for about 20% of human metabolism.

Question 24

What drives the action potential plainly said:

Answer 24

1.At rest, Potassium (+) is happy, but sodium (-) wants in. The balance of positives means that the inside is negative to the outside.

2.If an outside event causes that inside to be more positive, then, and only then, will sodium gates open and let sodium rush in.

3.Sodium rushing in means lots of positives in, which means the inside becomes positive= depolarization.

4.This in turn drives out the potassium as positives repel each other, making the cell negative again= repolarization (hyperpolarized)

5.The system is then reset by the Sodium-Potassium pump.

Question 25

What is synaptic cleft?

Answer 25

The sending cell does not directly connect with the receiving cell- the gap between the two cells.

Question 26

What is the presynaptic neuron?

Answer 26

The cell releasing information (before the gap between the two cells)

Question 27

What is the postsynaptic neuron?

Answer 27

The cell receiving the information (after the gap between the two cells)

Question 28

What is the gap known as?

Answer 28

The gap describes is called the synapse

Question 29

What are vesicles?

Answer 29

Vesicles contain neurotransmitters, which are chemical messengers

Question 30

How does the process of sending signals work?

Answer 30

When the signal arrives in the presynaptic axon terminal, the action potential causes vesicles to be free. After this the vesicles fuse with the membrane of the presynaptic cell and release the neurotransmitter into the synaptic cleft. The neurotransmitter then diffuses across the cleft over to the postsynaptic neuron’s membrane. However, membranes are impermeable to the external environment, so it finds neurotransmitter receptors (lock and key method). The cycle starts again and keeps going from neuron to neuron.

Question 31

During this process what makes an action potential more likely?

Answer 31

Gates that allow sodium to enter depolarize the postsynaptic neuron (an excitatory input)

Question 32

During this process what makes an action potential less likely?

Answer 32

Chlorine or potassium repolarize or hyperpolarize the postsynaptic neuron (an inhibitory input)

Question 33

When does reuptake happen and what is it?

Answer 33

Once the neurotransmitter has docked with the postsynaptic cell for some time, it is released back into the synapse, where it is taken back into/ recycled by the presynaptic cell. In simple terms, it is when the neurotransmitter is absorbed back into the neuron that released them.

Question 34

Why are potassium and sodium both positively charged but have different effects?

Answer 34

This is because sodium has a greater concentration outside the neuron compared to inside meaning there is an influx of positive charge that depolarizes the neuron, whereas potassium ions have a higher concentration inside the neuron compared to outside meaning there is an efflux of positive charge ions that hyperpolarizes the cell

Question 35

Hyperpolarize

Answer 35

makes the cell more negative

Question 36

Depolarize

Answer 36

makes the cell more positive

Question 37

How do drugs work on the brain?

Answer 37

Stimulating the release of more neurotransmitter (or mimicking the effects of a neurotransmitter) Inhibiting the release of more neurotransmitter (or by blocking the post-synaptic gates) Blocking the reuptake process, thereby prolonging the action of the body’s natural neurotransmitters (I.e. antidepressants)

Question 38

What are agonists?

Answer 38

Drugs that can enhance the action of a neurotransmitter- turns on the receptor.

Question 39

What are antagonists?

Answer 39

Drugs that hinder the activity of a neurotransmitter- blocks the receptor.

Question 40

What is the purpose of psychotropic/ psychoactive drugs?

Answer 40

Psychotropic/ psychoactive drugs can alter perception, mood, consciousness, cognition or behavior.

Question 41

What is Pharmacokinetics?

Answer 41

Pharmacokinetics is a branch of pharmacology that describes how the body absorbs and metabolizes substances.

Question 42

What does being a poor metabolizer entail?

Answer 42

Break down the drug slowly- leads to side effects.

Question 43

What does being an ultrarapid metabolizer entail?

Answer 43

Break down rapidly- leads to lack of symptom relief

Question 44

What is glutamate?

Answer 44

Glutamate is the major excitatory neurotransmitter in the brain and is often targeted by drugs that seek to reduce brain activity.

Question 45

What is the antonym of glutamate?

Answer 45

The opposite of glutamate in the brain is GABA, which is the major inhibitory neurotransmitter in the brain.

Question 46

What is acetylcholine?

Answer 46

Acetylcholine is the primary neurotransmitter used to activate motor neurons.

Question 47

Dopamine's function:

Answer 47

Dopamine is involved with excitement, movement, attention and learning.

Question 48

Norepinephrine's function:

Answer 48

Norepinephrine is involved with attention, vigilance and sleep.

Question 49

Serotonin's function:

Answer 49

Serotonin regulates mood, sleep, pain, sensory perception, and down regulates risk taking (unlike dopamine which increases it).

Question 50

How many of these neurotransmitters (dopamine, norepinephrine and serotonin) function at the same time?

Answer 50

Usually, all neurotransmitters operate at the same time, allowing for our highly flexible brains to function at such a high level.

Question 51

What is the endocrine system?

Answer 51

Hormones released by glands into the blood that target distant organs.

Question 52

What hormones are involved in the endocrine system and what are they involved in?

Answer 52

Steroid hormones: testosterone, estradiol, progesterone, cortisol Peptide hormones: oxytocin, vasopressin, prolactin, leptin

Question 53

How does the endocrine system work?

Answer 53

Hormones are more slowly acting, they travel through the blood