Nervous Tissue Ch 11

Question 1

How is the nervous system organize ?

Answer 1

The cns ( brain and spinal cord, control center)

The pns ( cranial and spinal nerves , communication life for the rest of of body )!

Question 2

List the functional division of pns

Answer 2

Sensory (afferet)
Visceral sensory ( skin, skeletal muscle, joints)
Somatic sensory division- visceral organs
Motor (effert) cns effectors
Visceral motor division- automatic nervous system

Question 3

What are the types of effectors?

Answer 3

Sympathetic- fight /flight
Parasympathetic- resting/ digesting
Somatic motor division
Effector - skeletal muscle

Question 4

What are the two types of cells found in the nervous system ?

Answer 4

Neurons - excitability nerve that transmit electrical nerve

Neurogial (glial) cell - supportive cell, sorruounds neurons

Question 5

What are the 6 types of neurologial cell ?

Answer 5

Oligodendrocytes
Astrocytes -( most abundant)
Sclensis - damage neurons replace by harden mass of atroscytes
Ependymal cell- lines cavity and provides CSf
Microglia- formed by monocytes , concentrate in infection, trauma and stroke

Question 6

What is oligodendrocytes?

Answer 6

Have processes that form myelin sheaths around cns nerve fibers

Question 7

What are the fundamental properties of neurons

Answer 7

Excitability- response to change in body/environment call stimuli

Conductivity- produce traveling electric signals

Secretion- when signal reaches end of nerve fiber, a chemical neurotransmitter is secreted

Question 8

What is the structure of a neuron?

Answer 8

Vast # of short dendrites ( receiving signals)

Cell body - soma

Rough ert ribosomes, no centrioles

Single axon arising from axon hillock ( trigger zone )

Axoplasm and axolemme

Question 9

What is axonal transport

Answer 9

Many proteins made in soma, must be transported to axon and axon terminal

First anterograde ( express train) : axon up to 400 mm/day for organelles, enzymes, vesicles and small molecules 
Soma for recycled materials and pathogens ( herpes) 

Slow transport ( local train) 
Moves cytoskeletal protein and new axoplasm at 10mm/day during repair in  damage axon

Question 10

Fundamentals types of neurons

Answer 10

Sensory: receptors detect change in environment/body
Info transmitted into brain or spinal cord

Interneurons( association neurons)
Between sensory and motor pathways in cns
90% are interneurons
Process and retrieve information

Motor efferent neuron : send signal out of muscle and gland cells,
Organs carry out responses called effectors

Question 11

What is the myelin sheath ?

Answer 11

Insulating layer around nerve fiber
Formed from wrapping of plasmas membrane 20% proteins 80% lipid ( looks white)

In pns 100’s of layers wrap axon , outter most coil is Schwann cells

In cns : no neurilemma or endometrium
Gaps between myelin segments - nodes of ranvier

Question 12

Speed of nerve impulses

Answer 12

Speed depends on diameter fiber and presence of myelin

Small Unmyelinated for - 0.5-2.0 m/sec
Small myelinated - 3-15.0 m/sec
Large myelinated- up to 120 m/sec

Question 13

Functions of nerve impulses

Answer 13

Slow signals -supply the stomach and dilate pupil

Fast signals - supply skeletal muscles and transport sensory signals for vision and balance

Question 14

Synapses between 2 neurons

Answer 14

First : released neurotransmitters onto 2nd neuron that responds to cl -( presynaptic)

2nd:synapses maybe be axodentric, axosomatic or axocixonic ( postsynaptic)

800 on spinal motor neuron
100,000 on neuron In cerebellum

Question 15

Resting membrane potentials

Answer 15

Potential difference across the membrane if resting cell
Approximately -70 mv
Cytoplasmic side negatively charged relative to outside

Generated by
Difference in ionic make up of ICF and ECF

Question 16

Depolarization vs hyperpolarization

Answer 16

Membrane potential move towards omv, inside becomes more positive ( less neg)

Membrane potential increases inside becoming more negative

Question 17

Excitability postsynaptic potentials

Answer 17

Local depolarization of postsynaptic membrane, brings neuron closer to ap
threshold neurotransmitter binding open chemically gated ions , allowing stimultaneous passage of na+ and cl -

Question 18

Inhibitory postsynaptic potentials

Answer 18

Local hyper polarization drives neuron away from ap threshold binding open k+ and cl-

Question 19

Summation vs no summation

Answer 19

Excitability and excitatory and inhibitory synapses added together

No summation : 2 stimili separated in time cause Epsps that do not add together

Question 20

Temporal summation vs spatial

Answer 20

Excitatory stimuli close in tune cause epsps that add together

2 simultaneous stimuli at different location cause rose thst add together spatial summation of epsp and iPsp

Change can cancel each other out

Question 21

3 kinds of synaptic transmission

Answer 21

Excitability cholinergic
Inhibitory gaba ergic
Excitatory adrenergic

Synapses delay .5 m/sec

Question 22

Excitatory cholinergic

Answer 22

Nerve signal opens voltage gated calcium channel
Trigger release of ach which cross synapse
Ach receptors trigger open na channel producing local potential

When recahsea threshold ( -55 nvm) triggers Ap

Question 23

Inhibitory gaba

Answer 23

Nerve signal triggers release of gaba ( y aminobutyric acid which cross synapses
Gaba receptors triggers open of cl channel producing hyper polarization
Postsynaptic is less likely to reach threshold

Question 24

Excitatory adrenergic snypanse

Answer 24

Neurotransmitter in norepinephrine ( n e)
Acts through second messenger system ( amp)
Receptor in intergral membrane proteins

Question 25

Amp multiple effects

Answer 25

Synthesis of new enzymes
Activating enzymes
Opening I gland gated or produce a postsynaptic potential

Question 26

Excitatory adrenergic

Answer 26

Cessation r modification of the signals
Mechanism to turn off stimulation
Synaptic knobs reabsorbs amino acids and monomers by eadocytes and break them down

Question 27

Neural integration

Answer 27

The more synapses, the greater it’s information processing capability

Cell in cerebral cortex
Cerebral cortex estimate to contain 100 trillion synapses
Chemical synapses are decision making components of nervous system

Ability to process store and recall info
-base on types of postsynaptic potentials produce by neurotransmitters

Question 28

Neural coding qualitative vs quantitative

Answer 28

Qualitative - salty/sweet depends on which neurons tried

Quantitative - strong stimuli excite different neurons ( different threshold)
Strong stimuli cause faster rate
Cns judges stimulus strength from firing frequent sensory neurons

Question 29

Neuron circuiate vs converging

Answer 29

Diverging circuit - 1 cell synapses on another that each synapses on another ( ex motor unit )

Input from many fibers on one neuron ( respiratory center , balance )

Question 30

Memory and synaptic plasticity

Answer 30

Memoirs not stored in individual cell
Physical basis of memory is a pathways of cell
- memory trace or engram
New synapses or exsisting synapses has been modified to make transmission easier