Bsc 2085 - Chapter 11

Front 1

What are the 3 main functions of the nervous system?

Back 1

Sensory input – the nervous system uses its millions of sensory receptors to monitor changes occurring both inside and outside the body. The gather information is called sensory input.

Integration – The nervous system processes and interprets sensory input and decides what should be done at each moment – a process called integration

3. Motor output – the nervous system activates effector organs – the muscles and glands – to cause a response, called motor output.

Front 2

What are the 2 main divisions of the nervous system?

Back 2

1. Central Nervous System - spinal cord and brain

2. Peripheral nervous system - the nervous system outside CNS. Consists mainly of nerves that extend from the brain and spinal cord (spinal nerves and cranial nerves)

Front 3

What are the 2 functional divisions of the PNS?

Back 3

1. Sensory or "afferent" - carrying toward - consists of axons that convey impulses to the CNS from sensory receptors

2. Motor or "efferent" carrying away - transmits impulses from the CNS to effector organs such as muccles and galdns

Front 4

What are the 2 PNS Motor Divisions?

Back 4

1. Somatic Nervous System - composed of motor nerve fibers that conduct impulses from CNS to skeletal muscles. voluntary nervous system

2. Autonomic Nervous System - consists of visceral motor nerve fibers that regulate activity of smooth muscles, cardiac muscles and glands. involuntary system

Front 5

Please describe the 2 functional subdivisions of the Autonomic Nervous System

Back 5

1. Sympathetic Division - fight or flight

2. Paraympathetic Division - rest and digest

Front 6

What are the 2 main types of cells in the Nervous System?

Back 6

1. Neurons - nerve cells that are excitable (responsive to stimuli) and transmit electric signals.

2. Neuroglia - small cells that wrap the more delicate neurons

Front 7

What are the 4 types of neuroglia found in the CNS

Back 7

1. Astrocytes - MOST ABUNDANT

2. Microglial

3. Ependymal

4. obligodenrocytes

Front 8

What are the 2 types of neuroglia found in the PNS

Back 8

1. satellite cells

2. schwann cells

Front 9

What are the 5 functions of Astrocytes?

Back 9

Play a role in making exchanges between capillaries and neurons, helping determine capillary permeability

Guide the migration of young neurons, and formation of synapses (junctions) between neurons

Control the chemical environment around neurons, where their most important job is “mopping up” leaked potassium ions and recapturing and recycling released neurotransmitters.

Respond to nearby nerve impulses and released neurotransmitters

Astrocytes influence neuronal functioning and therefore participate in information processing in the brain

Front 10

Where can ependymal cells be found?

Back 10

They line the central cavities of the brain and spinal cord

Front 11

Where can you find satellite cells

Back 11

Surround the neuron cell bodies in PNS, similar functions to astrocytes in CNS

Front 12

Where can you find the schwann cells? and what is their function?

Back 12

They are found in PNS, and they surround all nerve fibers in PNS and form myelin sheaths around the thick nerve fibers. They are similar to obligodendrocytes in CNS.

They are vital to regeneration of damaged peripheral nerve cells.

Front 13

What are three special characteristics of neurons?

Back 13

1. extreme longevitiy (over 100 years)

2. amitotic - lose ability to divide

3. high metabolic rate - cannot survive more than a few minutes without oxygen

Front 14

What is the function of the plasma membrane of neurons?

Back 14

Part of the receptive region that receives information from other neurons.

Front 15

The cell body is the __________________ center of a nueron

Back 15

Biosynthetic (where stuff is made)

Front 16

Clusters of cell bodies are called _______ in CNS

Clusters of cell bodies are called ________ in PNS

Back 16

NUCLEI in CNS

GANGLIA in PNS

Front 17

Bundles of nerve processes are called ___________ in the CNS

Bundles of nerve processes are called ______________ in PNS

Back 17

White matter tracts in CNS

nerves in PNS

Front 18

Based on information from neurotransmitters, dendrites send electrical signals TOWARD the neuronal cell body in the form of _____________________.

Back 18

GRADED potentials

(This is different from AP, which are nerve impulses generated by the AXON)

Front 19

The Axon generates and transmits nerve impulses called ___________________ AWAY from the neuronal body.

Back 19

Action Potentials

Front 20

Molecules and organelles are moved along the axons by motor molecules in what two directions?

Back 20

1. Anterograde movement (away)

2. Retrograde movement (towards)

Front 21

What are the main functions of the myelin sheath that wraps around the axon?

Back 21

1. Protect and electrically insulate the axon

2. Increase speed of nerve impulse transmission

3. Myelination is insulation

Front 22

What is neurilemma?

Back 22

Once the myelin sheath is formed, the nucleus and most of the cytoplasm of the schwann cell end up as a bulge just external to the myelin sheath. This portion of the Schwann cell, next to the exposed part of its plasma membrane is called the outer collar of perinuclear cytoplasm (formally known as neurilemma)

Front 23

How much faster is saltatory conduction in comparison to an unmyelinated axon? Why?

Back 23

30 times factor because it is a continuous conduction.

Front 24

Briefly define white matter and gray matter

Back 24

White matter – regions of brain and spinal cord containing dense collections of myelinated fibers are referred to as white matter. White matter are the “tracts”

Gray matter – contains mostly nerve cell bodies and nonmyelinated fibers. Grey matter are where the neurons live.

Front 25

Describe 3 structural types of neurons;

Back 25

1. Multipolar – have three or more processes – one axon and the rest dendrites. The MOST common type of neuron in humans

2. Bipolar – have two processes – an axon and a dendrite – that extend from opposite sides of the cell body. These rare neurons are found in some of the special sense organs.

3. Unipolar – have a single short process that emerges from the cell body and divides T-like into proximal and distal branches.

Front 26

Describe 3 functional types of neurons

Back 26

1.Sensory (or afferent) neurons – transmit impulses from sensory receptors in the skin or internal organs toward or into the central nervous system.

2. Motor (or efferent) neurons – carry impulses AWAY from the CNS to the effector organs (muscles and glands) of the body periphery.

3. Interneurons (association neurons) – lie between motor and sensory neurons in neural pathways and shuttle signals through CNS pathways and shuttle signals through CNS pathways where integration occurs.

Front 27

What are the 3 types of gated ion channels in a neuronal membrane?

Back 27

Chemically (“ligand”) gated – open when the appropriate chemical (i.e. neurotransmitter) binds

Voltage-gated channels – open and close in response to changes in the membrane potential

3. Mechanically gated channels – open and close in response to physical deformation of the receptor (as in sensory receptors for touch and pressure)

Front 28

What are the 2 types of membrane potentials (i.e. signals) ?

Back 28

Depolarization – decrease in membrane potential: the inside of the membrane becomes less negative (moves close to zero) than the resting potential Na+ coming in

2. Hyperpolarization – is an increase in membrane potential: the inside of the membrane becomes MORE negative than the resting potential Excessive K+ efflux, prior to closing

Front 29

Does the action potential decrease in magnitude over distancE?

Back 29

NO it does not. It is the PRINCIPLE means of long-distance neural communication.

Front 30

During the RESTING phase, what is the state of the Na+ and K+ channels?

Back 30

They are ALL closed.

Front 31

Ionic redistribution back to resting conditions is restored by what?

Back 31

Thousands of sodium-potassium ATPase pumps.

Front 32

Describe the 5 features associated with threshold

Back 32

Membrane has been depolarized by 15 to 20 mV (to about -55mV)

Na+ permeability increases

Na+ influx exceeds K+ efflux

The positive feedback cycle begin and an Action Potential is created.

Subthreshold stimulus causes a weak local depolarization that does not reach threshold.

Threshold stimulus is strong enough to push the membrane potential toward the threshold.

Front 33

What is multiple sclerosis?

Back 33

__Multiple Scleorsis (MS)____ is an autoimmune disease in which myelin sheaths in the CNS become nonfunctional ___hardened lesions “scleorses”___ (hardened). ____Shunts__ and ____short-circuits___ of nerve impulses occurs, and impulse conduction slows and eventually _____ceases___________.

Front 34

Whats the difference between a post synaptic and pre synaptic neuron?

Back 34

Presynaptic neuron – conducts impulses toward the synapse

Postsynaptic neuron – transmits impulses away from the synapse.

Front 35

What are the 2 most common types of synapses?

Back 35

AXODendritic (axon to dendrite)

AXOsomatic (axon to cell body)

Front 36

Where are electrical synapses found?

Back 36

Embryonic nervous Tissue. They are also found in some brain regions, e.g. hippocampus, areas associated with saccade eye movements, and Heart.

Front 37

How are neurotransmitter effects terminated?

Back 37

1. Diffusion away from the synaptic cleft

Front 38

What is synaptic delay?

Back 38

Neurotransmitter must be released, diffuse across the synapse, and bind to receptors. Synaptic delay is time needed to do this: 0.3-5.0 ms. Synaptic delay is the rate-limiting step of neural transmission.

Front 39

What are postsynaptic potentials determined by? And what are 2 types?

Back 39

1. Time the neurotransmitter is in the area.

OR IPSP – Inhibitory postsynaptic potentials

Front 40

Describe EPSP

Back 40

Neurotransmitter binds to and opens chemically gated channels that allow simultaneous flow of Na+ and K+ in opposite directions

Na+ influx is greater than K+ efflux, causing a net depolarization

EPSPs trigger AP at axon hillock if EPSPs summed together cause depolarization at the Threshold level.

Front 41

Describe IPSP

Back 41

Neurotransmitter binds to and opens channels for K+ or Cl-

Causes a hyperpolarization: the inner surface of membrane becomes more negative

Reduces the postsynaptic neurons ability to produce an action potential.

Front 42

Describe 3 characteristics of summation or integration of graded potentials:

Back 42

1. IPSPs can also summate with EPSPs, cancelling each other out.

Front 43

Describe temporal and spatial summation:

Back 43

Temporal Summation – One or more presynaptic neurons transmit impulses in rapid-fire order

Spatial Summation – postsynaptic neuron is stimulated by a large number of terminals at the same time.

Front 44

What is LTP and where is it found?

Back 44

(LTP = long term potentiation), found in HIPPOCAMPUS

Front 45

Most neurons make _______ or more neurotransmitters, which are released at different_________. Over _____ neurotransmitters have been identified.

Back 45

Most neurons make __two__ or more neurotransmitters, which are released at different__stimulation frequencies_. Over _50_ neurotransmitters have been identified.

Front 46

Where is Ach released? What enzyme helps synthesize it? What enzyme helps degrade it?

Back 46

Ach is released at neuromuscular junctions and some autonomic nervous system neurons.

Synthesize: ChAT (choline acetyltransferase)

Degrade: AchE (acetylcholinesterase)

Front 47

What are the 2 categories of biogenic amines? Name 3 catecholamines and 2 indolamines:

Back 47

Play various roles in emotional behaviors and the biological clock:

Cactecholamines – dopamine, norepinephrine (NE), and epinephrine

Indolamines – serotonin and histamine

Front 48

Name 4 amino acids

Back 48

GABA, GLycine, Aspartate, and Glutamate

Front 49

Name and Describe 3 peptides

Back 49

Substance P – mediator of pain signals

Endorphins – act as natural opiates; reduce pain perception

Gut-brain peptides – somatostatin and cholecystokinin (CCK)

Front 50

Name 2 gas neurotransmitters and describe their functions:

Back 50

Nitric Oxide (NO) – synthesized on demand

Activates the intracellular receptor guanylyl cyclase to make cyclic GMP

Involved in learning and memory

2. Carbon monoxide – is a regulator of cGMP in the brain

Front 51

Name a lipid neurotransmitter. What binds to it?

Back 51

Endocannabinoids

Binds with G protein – coupled receptors in the brain.

Lipid soluble; synthesized on demand from membrane lipid

Involved in learning and memory

THC of marijuana binds to this receptor

Front 52

Which neurotransmitters are inhibitory? What about excitatory?

Back 52

Inhibitory: GABA and Glycine

Excitatory: Glutamate

Front 53

Where is ACH excitatory? What about inhibitory?

Back 53

Excitatory: Neuromuscular junctions in skeletal muscle

Inhibitory: In cardiac muscle

Front 54

What are the 2 types of neurotransmitter receptors?

Back 54

Channel linked or "Ionotropic"

G Protein Linked or "Metabotropic"

Front 55

Describe G Protein linked (metabotropic) mechanism

Back 55

1. Activate genes and induce protein synthesis

Front 56

What can the "second messengers" from a g-protein mechanism do?

Back 56

1. Activate genes and induce protein synthesis

Front 57

What is serial processing and where is it used?

Back 57

Serial Processing – input travels along ONE pathway to a specific destination. Works in all-or-none manner to produce a specific response.

Examples:

1. Refelx Arcs (pathways) have five essential components: receptor, sensory neuron, CNS integration center, motor neuron and effectors

Front 58

What is parallel processing and where is it used?

Back 58

Parallel Processing – input travels along SEVERAL pathways.

One stimulus promotes numerous responses

Important for higher-level mental functioning

Example: A smell may remind one of the odor and associated experiences.