Lecture 3

Question 1

Nervous System Organization

Answer 1

Central nervous system: Brain and spinal cord.

Peripheral nervous system: Body.

Question 2

Peripheral Nervous System

Answer 2

Somatic: controls voluntary muscles with spinal nerves and cranial nerves.

Automatic: consists of autonomic nerves and some cranial nerves that control the function of organs and glands.

Question 3

Divisions of ANS

Answer 3

Sympathetic: fight or flight system.

Parasympathetic: predominates at times when the energy reserves can be conserved and stored for later use.

Question 4

Cerebral Spinal Fluid

Answer 4

• surrounds the brain and spinal cord.
• protects the brain.
• helps in the exchange of nutrients and waste products between the brain and blood.

Question 5

CNS has SIX distinct regions

Answer 5

1. ) Spinal Cord
2. ) Myencephalon (medulla)
3. ) Metencephalon (hindbrain)
4. ) Mesencephalon
5. ) Diencephalon (forebrain)
6. ) Telencephalon (forebrain)

Question 6

Myencephalon (medulla)

Answer 6

• origin of reticular formation.

- multiple cell groups regulating vital functions.

Question 7

Metencephalon (hindbrain)

Answer 7

• cerebellum & pons.

- plays a role in attention, arousal, sleep, muscle tone.

Question 8

Mesencephalon

Answer 8

• important for pain modulation.

- critical in initiation and modulation of movement.

Question 9

Diencephalon (forebrain)

Answer 9

• thalamus & hypothalamus.

- process and then distribute sensory and motor information.

Question 10

Telencephalon (forebrain)

Answer 10

• the cerebral hemisphere and the largest region of the brain, and include the external cerebral cortex.
• emotional responses, regulates motivated behavior & learning.

Question 11

Micro-Neuroanatomy

Answer 11

• There are 85 to 100 billion neurons in the brain.
• Neurons make 100 trillion synapses.
• 1 trillion glial cells.

Question 12

Neuron

Answer 12

Specialized nerve cells that form the brain, spinal cord, and nerves that transmit electrical signals throughout the body.

Question 13

Four Principle Types of Glial cells

Answer 13

1. ) Oligodendroglia
2. ) Microglia
3. ) Astrocytes
4. ) Schwann cells

Question 14

Oligodendroglia

Answer 14

• form myelin sheath on multiple axons in the CNS.

- provides energy efficient and fast neural conduction.

Question 15

Microglia

Answer 15

provide immune function.

Question 16

Astrocytes

Answer 16

• provide structural support (biggest).
• maintain ionic and chemical environment.
• store nutrients to provide energy for neurons.

Question 17

Schwann cells

Answer 17

supporting cells of the peripheral nervous system responsible for the formation/reformation of myelin.

Question 18

Electric Transmission

Answer 18

transmission of information within a single neuron is an electrical process and depends on the semipermeable nature of the cell membrane.

Question 19

Polarized

Answer 19

means that there is an electrical difference across the cell membrane.

Question 20

Two Main Ions

Answer 20

Sodium (NA = not allowed)

Potassium (K = keep)

Question 21

Resting Membrane Potential

Answer 21

• when a neuron is at rest, the inside of the neuron is negative (has more negatively charged ions) relative to the outside of the cell.
• 70mV.

Question 22

Gated Ion Channels

Answer 22

Most channels are not normally open to allow free passage of ions, but are in a closed configuration that can be opened momentarily by specific stimuli.

Question 23

Ligand-gated channels

Answer 23

• bind neurotransmitters and open in response to ligand binding.
• ion moves from high to low concentration.

Question 24

Voltage-gated channels

Answer 24

opened by the application of a small electrical charge to the membrane surrounding the channel.

Question 25

Local Potentials

Answer 25

small, local changes in ion distribution and electrical potential differences.

Question 26

Depolarization

Answer 26

- positively charged ions make the inside of the call slightly more positive in a small, localized area of the membrane, bringing the membrane potential a tiny bit closer to the threshold for firing. - small amounts of Na+ enter cell.

Question 27

Hyperpolarization

Answer 27

- increase in the negatively charged ion makes the call slightly more negative inside and brings the resting potential farther away from threshold. - small amounts of Cl- enter or K+ exit cell.

Question 28

Excitatory postsynaptic potentials (EPS)

Answer 28

- makes the postsynaptic neuron more likely to fire an action potential. - depolarization.

Question 29

Inhibitory postsynaptic potentials (IPSPs)

Answer 29

- makes a postsynaptic neuron less likely to generate an action potential. - hyperpolarization.

Question 30

Action Potential

Answer 30

- the rapid change in membrane potential that is propagated down the length of the axon. - the membrane potential must be changed from resting (-70mV) to the threshold for firing (-50mV).

Question 31

Axon Hillock

Answer 31

the portion of the axon that is adjacent to the cell body where electrical signal is generated.

Question 32

Five Stages of Action Potential

Answer 32

1. ) Resting State: Na+ and K+ channels are closed. 2. ) Depolarization: A stimulus opens some Na+ channels. 3. ) Depolarization opens most sodium channels, while potassium remains closed. 4. ) Falling phase: most Na+ channels become inactivated, blocking Na+ inflow. K+ channels open, making K+ outflow. 5. ) Undershoot: Na+ channels close, but some K+ channels are still open. As the K+ channels close and Na+ become unblocked, the membrane returns to resting state.

Question 33

Saltatory Conduction

Answer 33

The process by which if insulating myelin is present on an axon then the nerve impulses that is conducted will "jump" from gap to gap in the myelin layer.

Question 34

Node of Ranvier

Answer 34

A small gap between myelinated segments where axonal membrane is exposed; increases speed of impulses.

Question 35

Axodendritic transmission

Answer 35

- axon to dendrite and spines. | - most common.

Question 36

Axosomatic transmission

Answer 36

axon to cell body.

Question 37

Axoaxonic transmission

Answer 37

axon to axon.

Question 38

Synaptic Cleft

Answer 38

The gaps between neurons, where chemical signals are transmitted.

Question 39

Synapse

Answer 39

a structure that permits a neuron to pass an electrical or chemical signal to another neuron.

Question 40

Presynaptic Neuron

Answer 40

release zone, where terminals are.

Question 41

Postsynaptic Neuron

Answer 41

the neuron on the receiving end of the synapse, where the dendrites are.

Question 42

Synaptic Factors

Answer 42

Action potential Probability of release Heteroreceptors: receptors for other transmitters released at axoaxonic synapses. Autoreceptors: receptors for the same transmitter released by the neuron.

Question 43

Terminal autoreceptors

Answer 43

located on axon terminals, and when activated by neurotransmitter, their main function is to inhibit further transmitter release.

Question 44

Somatodendritic autoreceptors

Answer 44

found on the cell body or dendrites. when these autoreceptors are activated, they slow the rate of cell firing.

Question 45

Ionotropic receptors

Answer 45

Ligand-gated ion channel. Fast response.

Question 46

Metabolic receptors

Answer 46

Activate other proteins called G proteins. Slow.

Question 47

Second Messengers

Answer 47

- Activate protein kinases (enzymes that phosphorylate proteins). - Given numerous roles of proteins (receptors, enzymes, channels, etc) can lead to several downstream effects.

Question 48

Tyrosine Kinase Receptors

Answer 48

Enzymes that phosphorylate proteins.

Question 49

How might drugs affect neurotransmitters?

Answer 49

- A drug can block the reuptake transporter, so the neurotransmitter will stay inside. Ex: SSRI’s it blocks the reuptake of serotonin.

Question 50

Nitric Oxide

Answer 50

a gas that performs a type of signaling between neurons.

Question 51

Endocrine System

Answer 51

- a collection of glands and groups of cells that secrete hormones that regulate growth,development, and homeostasis. - drugs can alter the secretion of many hormones, causing physiological abnormalities.