A&p Chapter 6

Front 1

What are the 2 main parts of the nervous system of the body?

Back 1

Central Nervous System (CNS) brain and spinal cord in dorsal body cavity and
Peripheral Nervous System (PNS) cranial and spinal nerves.

Front 2

What are the 2 subdivisions of the Peripheral Nervous System (PNS)?

Back 2

Afferent or sensory and Efferent or motor.

Front 3

Distinguish between afferent and efferent nerves.

Back 3

Afferent nerves go to the CNS from sensory receptors in the body; travel from outside in; Efferent goes from CNS out to organs, muscles; travel from inside out.

Front 4

2 Subdivisions of the efferent division?

Back 4

Somatic NS: somatic nerve fibers; CNS-skeletal muscle-voluntary NS.
Autonomic NS: visceral motor fibers; controls cardiac, smooth muscle, glands, involuntary.

Front 5

2 Subdivisions of the ANS?

Back 5

Sympathetice NS & Parasympathetic NS

Front 6

4 types of Neuroglial Cells in CNS

Back 6

Astrocytes, Microglial, ependymal, Oligodendrocytes

Front 7

2 types of Neuroglial Cells in PNS

Back 7

Satellite & Schwann

Front 8

Neurons

Back 8

conduct impulses from one part of the body to another and are the structural units of the nervous system.

Front 9

3 special characteristics of neurons

Back 9

extreme longevity, highly differentiated and lose ability to divide/replicate (amitotic) and have high metabolic rate.

Front 10

Neurons cell body

Back 10

main part of neuron cell

Front 11

Ganglia

Back 11

Cluster of cell bodies in PNS

Front 12

Nuclei

Back 12

Cluster of cell bodies in CNS

Front 13

Processes

Back 13

arm like projections that extend from cell body of all neurons

Front 14

Tracts

Back 14

bundles of neuron processes in CNS

Front 15

Nerves

Back 15

bundles of neuron processes in PNS

Front 16

Dendrite

Back 16

receptive or input region of neuron

Front 17

Axon

Back 17

each neuron has 1, starts at axon hillock, may be short or long, may have branches called axon collaterals; this is what generates and conducts nerve impluses.

Front 18

Anterograde

Back 18

move along from the cell body to the axon terminal

Front 19

Retrograde

Back 19

move from axon terminal to cell body

Front 20

Myelin Sheath

Back 20

fatty protein sheath that protects and insulates nerve fibers; makes conduction faster, more energy efficient. Formed by Schwann cells.

Front 21

Nodes of Ranvier

Back 21

gaps between Schwann cells; the un-myelinated part of neuron where impulses are conducted.

Front 22

3 functional classes of nerves are

Back 22

Sensory (afferent), Motor (efferent), Interneurons.

Front 23

Sensory Nerves

Back 23

Receives, usually unipolar, cell bodies are in sensory ganglia, outside the CNS.

Front 24

Motor Nerves

Back 24

Sends impulses away from CNS to organs.

Front 25

Interneurons

Back 25

Make up 99% of neurons in the body, multipolar.

Front 26

Action Potential

Back 26

when neurons are stimulated they generate electrical current that conducts along length of axon resulting in a nerve impulse.

Front 27

Voltage

Back 27

potential energy generated by seperate charges; measured in volts or millivolts

Front 28

Cell membranes are electrically charged...

Back 28

the difference in charge (# of ions) generates electric potential; by seperating charges you create potential energy. Allows for control of ion flow over, into and out of cell.

Front 29

Ligand gated channels

Back 29

open to neurotransmitters

Front 30

Voltage gated channels

Back 30

open or close in response to change of membrane potential or electrical charge.

Front 31

Resting membrane potential

Back 31

-70mv, more negative inside cell and more positive outside cell. Sodium (Na+) outside
Potassium (K+) inside

Front 32

Depolarization

Back 32

lowers membrane potential; from -70 toward 0

Front 33

Hyperpolarization

Back 33

increases membrane potential; from -70 to -100

Front 34

Repolarization

Back 34

return to resting membrane potential after depolarization occurs. More negative

Front 35

Graded potential

Back 35

local change in membrane potential that occurs in varying grades of magnitude (lots of small stimuli occurring one after another) short distance signal only.

Front 36

Physiological definition of Action Potential

Back 36

brief reversal of membrane potential followed by repolarization

Front 37

5 Steps, generation of AP

Back 37

1)cell membrane at rest is stimulated 2)Na+ flows into cell causing depolarization 3)Na ion closes K+ flows out, repolarization occurs4)Hyperpolarization occures K+ flows out, Na+ channels close5)NaK ATPase pump keeps ion balance

Front 38

Propagation of AP

Back 38

propagates away from the source, in one direction, away from stimulus along entire length of axon.

Front 39

All or Nothing

Back 39

certain threshold must be reached for axon to fire or nothing happens - like firing a gun.

Front 40

Refractory Period

Back 40

After being activated, this is the rest time when it cannot be stimulated; prevents backflow.

Front 41

2 factors that affect conduction velocity

Back 41

1) Axon diameter, bigger faster than smaller 2) Degree of Myelination

Front 42

Saltatory Conduction

Back 42

means by which an AP is conductedn along a myelinated nerve fiber - jumping from one NOR to next.

Front 43

Synapse

Back 43

specialized junction between two neurons;AP in presynaptic neuron influences membrane potential of postsynaptic neuron by release of chemical messenger.

Front 44

2 kinds of synapse

Back 44

Axodendritic: axon joins to dendrite, presynaptic
Axosomatic: axon joins to cell body, postsynaptic

Front 45

Chemical Synapse

Back 45

specialized for release/receipt of neurotransmitters. axon terminal and neurotransmitter R seperated by synaptic cleft.

Front 46

Chemical Synapse - 5 steps to transfers

Back 46

1)ca2+ channel opens due to nerve impule (voltage gated)2)neurotransmitter released3)neurotransmitter binds to postsynaptic R4)ion channels open in postsynaptic membrane (ligand gated)5)degradation of neurotransmitters by enzymes (ach)

Front 47

EPSP

Back 47

neurotransmitter causes depolarization of postsynaptic membrane which causes local graded potential depolarization. Many EPSP's to fire a neuron.

Front 48

IPSP

Back 48

neurotransmitter binding decreases ability to generate AP in postsynaptic neuron, which leads to hyperpolarization of membrane.

Front 49

2 types of summation

Back 49

Temporal: many fires in quick succession Spatial: stimulation by many axon terminals.

Front 50

Presynaptic Inhibition

Back 50

excitatory neurotransmitter from 1 neuron is inhibited by activity of a 2nd.

Front 51

Neuromodulation

Back 51

neurotransmitter acts via slow changes in cells' metabolism to modify neuronal activity or another chemical/hormone modifies neuron activity.

Front 52

5 most common neurotransmitters

Back 52

Acetylcholine (ach), biogenic amines, amino acids, peptides, novel messengers. ach found on skeletal muscle neurons, peptides involved in pain perception.

Front 53

2 modes of neurotransmitters

Back 53

excitatory or inhibitory

Front 54

2 kinds of neurotransmitter receptors

Back 54

direct: ion channel linked, fast synaptic transmission or indirect: G protein couple receptor, slow responses, goes through 2 messengers.

Front 55

4 main regions of brain

Back 55

cerebral hemispheres, diencephalons, brain stem, cerebellum

Front 56

CNS pattern

Back 56

central cavity surrounded by gray matter core with white matter on outside

Front 57

Cortex

Back 57

Outer layer of gray matter found on cerebral hemispheres and cerebellum

Front 58

Ventricles

Back 58

hollow filled with cerebral spinal fluid, lined by ependymal cells; have c shaped paired ventricles separated by a thin membrane, both in contact with narrow 3rd ventricle.

Front 59

Cerebral hemispheres

Back 59

85% of brain mass, at top of brain

Front 60

Gyri

Back 60

elevated ridges of cerebral hemisphere

Front 61

Sulci

Back 61

grooves that separate sulci in cerebral hemisphere; divides each hemisphere into 5 lobes: frontal, parietal, occipital, temporal, cerebellum

Front 62

Fissure

Back 62

deep grooves that separate large regions of the brain

Front 63

Longitudinal Fissure

Back 63

Separates hemispheres

Front 64

Transverse Cerebral fissure

Back 64

separates cerebral hemispheres from cerebellum

Front 65

Cerebral Cortex

Back 65

conscious mind; very complex, each hemisphere controls opposite side of body, each side not equal, 3 functional areas are motor, sensory and association.

Front 66

Basal nuclei

Back 66

several masses of gray matter located deep within the white matter of the cerebrum; play important inhibitory role in motor control

Front 67

3 parts of Diencephalon

Back 67

Thalamus:sorts/edits info going to cerebral cortex, hypothalamus: regulation of homeostasis, Epithalamus: regulates sleep cycle.

Front 68

3 parts of brain stem

Back 68

midbrain: fight or flight, pons: conducts tracts between spinal cord & brain, medulla oblangata: maintenance of homeostasis.

Front 69

Cerebellum

Back 69

located dorsal to pons and medulla-separated by transverse cerebral fissure; balance, muscle tone, coordination of voluntary muscle activity.

Front 70

Functional Brain System

Back 70

network of neurons that work together but span large distances in the brain; examples are limbic system and reticular activating system (RAS).

Front 71

Limbic System

Back 71

made up of cerebral cortex, basal nuclei, thalamus and hypothalamus; plays role in emotions, motivations, learning.

Front 72

RAS

Back 72

network of neurons in brain stem which receives and integrates synaptic input; helps one to direct attention and alertness. Affected by alcohol/tranqualizers; injury causes coma.

Front 73

Spinal Cord

Back 73

2 way conduction pathway to and from brain; protected by bone, meninges and CSF; major reflex center.

Front 74

PNS receptor form the

Back 74

dorsal roots of spinal cord.

Front 75

Spinal cord trauma

Poliomyelitis

Back 75

leads to paralysis; destroys anterior horn motor neurons, usually fatal due to paralysis of respiratory muscles.

Front 76

PNS

Back 76

Voluntary control, all neural structures outside brain and spinal cord; consists of cranial nerves and spinal nerves

Front 77

Cranial Nerves

Back 77

I Olfactory, nasal mucosa, II Optic, brain tract, III Oculomotor, move eyeball, IV Trochlear, extrinsic eye muscle, V Trigeminal, chewing, VI Abducens, laterally turn eye, VII Facial, facial expression, VIII Vestibulocochlear, balance, IX Glossopharyngeal, innervates tounge, X Vagus, goes to thorax, XI Accessory, part of vagus, XII Hypoglossal, tounge movement.

Front 78

Spinal Nerves

Back 78

31 pairs, arise from spinal cord to supply all parts of body but head and neck. Mixed nerves that conncect to spinal cord by dorsal(afferent) and ventral(efferent) root

Front 79

ANS

Back 79

Involuntary control, maintains stability of internal environment; blood flow, heart rate, gland secretions.

Front 80

Effectors of somatic NS and ANS?

Back 80

somatic - skeletal muscle
ANS - cardiac, SM glands

Front 81

Sympathetic versus Parasympathetic

Back 81

serve same organs but have opposite effects; PS resting and digestion S fight or flight.

Front 82

BBB-Blood Brain Barrier

Back 82

maintains stable environment for brain, endothelial cell layer in capillary wall has tight junctions makes it impermeable to most substancces.

Front 83

Cerebral Spinal Fluid

Back 83

special brain cushioning fluid the brain floats in

Front 84

Choroid Plexus

Back 84

where CSF is formed

Front 85

Substances that cross the BBB

Back 85

Glucose, water, lipids, amino acids

Front 86

Protective layers over the brain

Back 86

bones, membranes, CSF, BBB

Front 87

Three meninges (membranes) that protect the brain are:

Back 87

dura mater: tough, inelastic layer; arachnoid mater: full of CSF, pia mater: closest to brain, forms CSF.

"Three mothers"