week 2- The nervous system

Question 1

Describe the structure of the nervous system, with reference to the major divisions: central versus peripheral, sensory versus motor, somatic versus autonomic.

Answer 1

the nervous system is a complex network of specialized cells working together to coordinate the functions of the body.
the nervous system can be divided into two key main subdivisions.
The CNS and the PNS

the CNS consists of the spinal cord and the brain. the spinal serves as a channel for nerve impulses that travel to and from the brain and the brain processes and integrates messages from the PNS as well as generating responses to stimuli.

the PNS is everything else in the body it includes all the nerves that extend from the CNS to the rest of the body. it can be further divided into the somatic and the autonomic nervous systems. The somatic nervous system controls voluntary movements and sensory information from the skin, muscles, and joints. the autonomic nervous system is all the body’s involuntary movements such as breathing, heart rate, and digestion, and is further divided into the sympathetic division and the parasympathetic division.

Question 2

somatic nervous system

Answer 2

the somatic nervous system is all the body’s voluntary movements and receives sensory information from the skin, muscles, and joints.

Question 3

autonomic nervous system

Answer 3

the autonomic nervous system is all the body’s involuntary movements such as heart rate, breathing, and digestion, and is further divided into sympathetic and parasympathetic divisions

Question 4

Sympathetic divisions

Answer 4

the sympathetic division is responsible for “fight or flight”, which prepares the body for action in response to a perceived threat. It increases heart rate, breathing rate, and blood pressure while also slowing down digestion and other non-essential body essentials.

Question 5

Parasympathetic division

Answer 5

The parasympathetic nervous system is responsible for the “rest and digest” response, which allows the body to rest and recover. It slows down heart rate, breathing rate, and blood pressure, while also promoting digestion and other bodily functions.

Question 6

the central nervous system

Answer 6

the central nervous system consists of the brain and spinal cord. the brain is always receiving and integrating information and responding to stimuli while the spinal cord is a channel for nerve impulses to travel to and from the brain.

Question 7

The peripheral nervous system

Answer 7

PNS provides links to and from world outside our body

Question 8

Describe cell types of the nervous system; neuroglia vs neurons

Answer 8

Nervous tissue consists of two principal cell types:
Neuroglia (glial cells): small cells that surround and wrap delicate neurons

-Support and protect neurons

-Make up half the volume of the nervous system Many types in CNS and PNS

vs

Neurons (nerve cells): excitable cells that transmit electrical signals

-Basic functional units of the nervous system Send and receive signals

-Function in communication, information processing, and control

Question 9

identify the major components of a neuron

Answer 9

the major components of a neuron are the

cell body,
axon,
and dendrites.

Question 10

cell body

Answer 10

Contains the nucleus
produce neurotransmitters (Nissl bodies)
The plasma membrane can receive information from other neurons

Question 11

axon

Answer 11

-Generate and transmit action potentials
-release neurotransmitters from the axonal terminals
-provides movement of molecules to and from the cell body

Question 12

dendrites

Answer 12

Receive information and convey towards the cell body

Question 13

Define Resting Membrane potential (RMP) and factors that maintain the RMP

Answer 13

RMP is the membrane potential of a resting cell or in other words, it is the voltage difference between the inside and the outside of the cell.

–the RMP in neurons is about -45 to -90 millivolts (on average about -70 mV).

Question 14

passive ion channels (leak channels)

Answer 14

• always open
  -permeability changes with conditions

Question 15

active ion channels (gated ion channels)

Answer 15

-open and close in response to stimuli
-at resting membrane potential most are closes

Question 16

Define the events of the action potential

Answer 16

1 – resting state: all Na+ and K+ gated channels are closed, membrane potential at resting
level. 2 – depolarization: Na+ channels are open, Na+ flows into the cell; the inside of the membrane becomes less negative than the resting potential.
3 – repolarization: Na+ channels inactivating, K+ channels are open, K+ ions move out of the cell; the membrane returns to its resting membrane potential.
4 – hyperpolarization: some K+ channels remain open, some K+ ions move out of the cell; the inside of the membrane becomes more negative than the resting potential.

Question 17

define the factors that regulate the action potential

Answer 17

the factors that regulate the action potential include
-threshold
-all or none law
-mylinatiion

Question 18

Threshold

Answer 18

Depolarization of membrane by 15 to 20 mV to induce the action potential firing.

Question 19

Rate of impulse propagation

Answer 19

is determined by
1) Axon diameter – the larger the diameter, the faster the impulse;

2) Presence of a myelin sheath – myelination dramatically increases impulse speed. Saltatory conduction occurs in myelinated axons; Action potentials are triggered only at the nodes of Ranvier (gaps between Schwann cells) and jump between the nodes.

Question 20

Na+ -K+ pump

Answer 20

maintains the concentration gradient , it constantly expels three Na+ ions from the cell, and moves two K+ ions back into the cell.

Question 21

define synaspe

Answer 21

The functional junction between 2 neurons or between a neuron and an effector cell that mediates information transfer.

Presynaptic neuron – conducts impulses toward the synapse;

Postsynaptic neuron – transmits impulses away from the synapse.

Question 22

Distinguish between electrical and chemical synapses

Answer 22

electrical synapse is when The membranes of the two communicating neurons are linked together by a gap junction that contains precisely aligned, paired channels in the membrane of the pre-and postsynaptic neurons, each channel pair forms a pore. As a result, an ionic current and some substances (eg. ATP) diffuse through the gap junction pores. Transmission is fast.

where a chemical synapse is Specialized for the release and reception of neurotransmitters.
Typically composed of two parts:
1) Axonal terminal of the presynaptic neuron, which contains synaptic vesicles;
2) Receptor region on the postsynaptic neuron.

Question 23

Define neurotransmitter action at the synapse

Answer 23

Neurotransmitters are chemicals that help neurons communicate with each other. They are made in one neuron and travel to another neuron through a small space called the synapse. Once there, they bind to receptors on the second neuron, which can either make it more likely to fire or less likely to fire an action potential. After they have done their job, neurotransmitters are either reabsorbed or broken down.

Question 24

Describe neurotransmitters

Answer 24

neruotransmitters are endogenous chemicals which relay, amplify, and modulate signals between a neuron and another cell; they are made in the cell body and packaged into synaptic vesicles in the nerve terminals on the presynaptic side of a synapse.

Question 25

neurotransmitters: Acetylcholine

Answer 25

Excitatory to vertebrate
skeletal muscles

and excitatory or inhibitory at other sites

Secretion Sites
CNS, PNS, vertebrate neuromuscular junction

Question 26

neurotransmitters: GABA (gamma
aminobutyric acid) (amino acid)

Answer 26

function: Inhibitory
secretion cite :CNS

Question 27

neurotransmitters :Glycine(amino acid )

Answer 27

function: Inhibitory
secretion cite: CNS

Question 28

neurotransmitters: glutamate (amino acid)

Answer 28

function: Excitatory
secretion cite CNS; invertebrate
neuromuscular junction

Question 29

neurotransmitter: Aspartate

Answer 29

function: Excitatory
secretion cite: CNS

Question 30

neurotransmitter:Norepinephrine (Biogenic Amines)

Answer 30

Excitatory or inhibitory
CNS: PNS

Question 31

neurotransmitter: (Biogenic Amines) Dopamine

Answer 31

Generally excitatory; may
be inhibitory at some sites
CNS; PNS

Question 32

neurotransmitter: (Biogenic Amines) Serotonin

Answer 32

Generally inhibitory
CNS

Question 33

Neuropeptides (a very diverse group, only two of which are shown)

Answer 33

Substance P
Excitatory
CNS; PNS

Met-enkephalin
(an endorphin)
Generally inhibitory
CNS