Anatomy And Physiology: Chapter 12- Nerve Tissue

Front 1

System controls and integrates all body activities within limits that maintain life.

Back 1

Nervous System

Front 2

3 basic functions of nerve tissue:

Back 2

1. Sensing - changes with sensory receptors internally and externally.
2. Integration - (interpreting, remembering) changes in the internal and external environment.
3. Respond - (reacting) to changes with effectors by muscular contractions (smooth, cardiac, and skeletal) and grandular secretions.

Front 3

The nervous system is made of:

Back 3

the brain, cranial nerves, spinal cord, spinal nerves, ganglia, enteric plexuses, and sensory receptors.

Front 4

What are the two major divisions of the nervous system?

Back 4

Central and peripheral nervous system

Front 5

Made of the brain and spinal cord.

Back 5

Central nervous system (CNS)

Front 6

Made of the cranial and spinal nerves that contain both sensory and motor fibers.

Back 6

Peripheral nervous system (PNS)

Front 7

The PNS connects CNS to muscles, glands, and all sensory receptors. The PNS can be subdivieded into what?

Back 7

Somatic and autonomic nervous system

Front 8

Voluntary, neurons travel from the skin and special sensory receptors to the CNS and motor neurons travel to skeletal muscle tissue.

Back 8

Somatic nervous system

Front 9

Involuntary, sensory neurons travel from visceral organs to the CNS and motor neurons travel to the smooth and cardiac muscles and glands.

Back 9

Autonomic nervous system

Front 10

(fight or flight); explain effects on organs

Back 10

Sympathetic division

Front 11

(rest and repose); returns the body to normal; rest and digest

Back 11

Parasympathetic division

Front 12

Involuntary sensory and motor neurons control the GI tract. The neurons function independently of ANS and CNS.

Back 12

Enteric nervous system

Front 13

functional unit of nervous system. Most do not divide, they have the capacity to produce action potential.

Back 13

Neurons

Front 14

made of a single nucleus with a prominent nucleolus, nissl bodies (rough ER), neurofilaments which give the cell shape and support, and microtubules that move material inside the cell.

Back 14

Cell body

Front 15

carry messages into the cell body; short, highly branched, and unmyelinated (wires been stripped away).

Back 15

Dendrite

Front 16

carry impulses away from the cell body; long, thin, cylindrical process of the cell.

Back 16

Axons

Front 17

Side branches (collaterals) of the axon end in fine processes called:

Back 17

axon terminals

Front 18

They contain vesicles filled with neurotransmitters.The swollen tips of an axon are called:

Back 18

synaptic end bulbs

Front 19

(lock jaw) bacteria that enters the body through the axons of neurons. Disrupts motor neurons and causes painful muscle spasms.

Back 19

Clostridum tetani

Front 20

Viruses that also enter the axon and go to the cell body and CNS.

Back 20

Rabies & herpes viruses

Front 21

Neurons are classified according to the number of processes that extend away from them.

Back 21

1. Unipolar neuron- 1 process
2. Bipolar neuron- 2 processes
3. Multipolar neuron- have many dendrites and a single axon. Majority of the neurons in the CNS are of multipolar type.

Front 22

(Afferent neurons) transport sensory information from the skin, muscles, joints, sense organs, and viscera to the the CNS.

Back 22

Sensory

Front 23

(Efferent neurons) send motor nerve impulses to muscles and glands and other neurons.

Back 23

Motor

Front 24

(Association neurons) connect sensory to motor neurons. These make up 90% of the neurons in the body.

Back 24

Interneurons (between two neurons)

Front 25

Do not produce action potentials. They make up half of the volume of the CNS. They are smaller than neurons and are 50X more numerous.

Back 25

Neuroglial cells

Front 26

Neuroglial cells divide rapidly to form tumors called:

Back 26

gliomas

Front 27

There are 4 neuroglial cell types in the CNS:

Back 27

astrocytes, oligodendrocytes, microglia, and ependymal

Front 28

There are 2 neuroglial cell types in the PNS:

Back 28

schwann and satellite cells

Front 29

Star shaped cells, form the blood-brain barrier by covering blood capillaries, metabolize neurotransmitters, regulate potassium + balance, provide structural support.

Back 29

astrocytes

Front 30

Most common glial cell type, forms myelin sheath around more than one axon in the CNS. Schwann cells of PNS produce myelin around only individual axons.

Back 30

oligodendrocytes

Front 31

small cells found near blood vessels. They're phagocytic- they clear away dead cells. They're derived from cells that also gave rise to macrophages and monocytes.

Back 31

microglia cells

Front 32

form epithelial membrane lining cerebral cavities and central canal. They produce cerebrospinal fluid (CSF).

Back 32

ependymal

Front 33

flat cells surrounding neuronal cell bodies in peripheral ganglia. They support neurons in the PNS ganglia (group of cells).

Back 33

satellite cells

Front 34

Schwann cells encircle PNS axons. Each cell produces part of the myelin sheath surrounding an axon in the PNS.

Back 34

Schwann cells

Front 35

a lipid and protein covering that is produced by Schwann cells.

Back 35

myelin

Front 36

cytoplasm and nucleus of Schwann cells

Back 36

neurilemma (nerve cell membrane)

Front 37

plasma membrane of the Schwann cell

Back 37

myelin sheath

Front 38

the gaps of Schwann cell are called the:

Back 38

nodes of Ranvier

Front 39

myelin fibers appear what color

Back 39

white

Front 40

acts as an "ion insulator." They speed conduction of nerve impulses. They allow nerve impulse to jump and slide.

Back 40

myelin

Front 41

Slow, small diameter fibers, gray. They're only surrounded by neurilemma but no myelin sheath wrapping.

Back 41

unmyelinated fibers

Front 42

myelinate axons in the CNS

Back 42

oligodendrocytes

Front 43

myelinated processes (white in color)

Back 43

white matter (fat)

Front 44

nerve cell bodies, dendrites, axon terminals, bundles of unmyelinated axons and neuroglia (gray color).

Back 44

gray matter (no insulation)

Front 45

In the spinal cord

Back 45

gray matter forms an H-shaped inner core surrounded by white matter

Front 46

In the brain

Back 46

a thin outer shell of gray matter covers the surface and is found in clusters called nuclei inside the CNS

Front 47

Neurons are excitable due to

Back 47

the voltage difference created by a flow of the ions Na and K across the neuron membrane

Front 48

occurs because of the unequal distributions of ions which causes the membrane to the "charged"

Back 48

Resting membrane potential

Front 49

More negative ions (K) are found along the inside of the cell membrane and more positive ions ( Na and Cl= Salt) are along the outsideof the membrane at rest

Back 49

Resting membrane potential

Front 50

potential energy difference is

Back 50

-70mv and the cell is said to be "polarized"

Front 51

always open, this is what allows the K to leak out of the cell for the action potential to occur.

Back 51

leakage (nongated) channels

Front 52

open and close in response to stimulus, this causes excitablitliy.

Back 52

gated channels

Front 53

open in response to change in voltage. Ex: electricity

Back 53

voltage gated

Front 54

open and close in response to chemical stimuli such as hormone and neurotransmitters.

Back 54

ligand-gated

Front 55

open with mechanical stimulation

Back 55

mechanically gated

Front 56

open and close due to light stimulation

Back 56

light-gated

Front 57

membrane becomes more negative on the inside

Back 57

hyperpolarization

Front 58

membrane becomes more positive on th inside. Na come in

Back 58

depolarization

Front 59

with stimulation, an action potential either happens one specific way or not at all, lasts 1/1000 of a second.

Back 59

all-or-none principle

Front 60

period of time during which the neuron cannot generate another action potential

Back 60

refractory period of action potential

Front 61

even a very strong stimulus will not begin another action potential

Back 61

absolute refractory period

Front 62

a supra-threshold stimulus will be able to start an action potential, extra gates will have to open to start an action potential.

Back 62

relative refractory period

Front 63

traveling action potential is called a

Back 63

nerve impulse

Front 64

prevent opening of voltage-gated sodium channels. The nerve impulse cannot pass along the anesthetized nerve, and the CNS doesn't perceive the pain.

Back 64

local anesthetics

Front 65

blocks the sodium gates

Back 65

Novacaine and lidocaine

Front 66

occus in unmyelinated fibers-it is a step-by-step depolarization of each portion of the length of the neuron.

Back 66

continuous conduction

Front 67

occurs in myelinated fibers. The depolarization only occurs at the nodes of Ranvier where there is a high density of voltage-gated ion channels. The impulse jumps from node to node and is much faster.

Back 67

saltatory conduction

Front 68

action potential reaches the end bulb and the calcium channels open.

Back 68

chemical synapses

Front 69

flows inward which triggers the release of neurotransmitters.

Back 69

calcium

Front 70

crosses the synaptic cleft and binds to the ligand-gated receptors, the more released the greater the change in potential of the postsynaptic cell.

Back 70

neurotransmitters

Front 71

information can only travel from the dendrite to the cell body to the axon and away from the neuron because

Back 71

the neurotransmitters are located at the end of the axon.

Front 72

removed by diffusion into the blood stream, enzymatic degradation (ex: acetylcholinesterase degrades acetylcholine), or uptake by neurons.

Back 72

neurotransmitters

Front 73

anything that enhances a neurotransmitter such as a drug that mimics a natural neurotransmitter

Back 73

agonist

Front 74

anything that blocks the action of a neurotransmitter

Back 74

antagonist

Front 75

24-48 hours after injury Nissl bodies break up into fine granular masses.

Back 75

chromatolysis

Front 76

occurs by 3-5 days. This is a break down of the axon and myeline sheath distal to the injury, retrograde degeneration occurs back one node.

Back 76

Wallerian degeneration

Front 77

autoimmune disorder causing destruction of myeline sheaths in the CNS. Symptoms include muscular weakness, abnormal sensations or double vision.

Back 77

Multiple Sclerosis (MS)

Front 78

second most common neurological disorder. Affects 1% of the population. Characterized by short, recurrent attacks initiated by electrical discharges in the brain.

Back 78

epilepsy

Front 79

associated with tumors, vaccination, bacterial infections. possible paralysis

Back 79

Guillain- Barre syndrome

Front 80

malignant tumor that consists of immature nerve cells

Back 80

neuroblastoma

Front 81

burning unpleasant tiggling feeling, associated with diabetics

Back 81

neuropathy

Front 82

carried by rabbits and squirrels, fatal disease caused by a virus that reaches the CNS. Transmitted by the bite of an infected animal/mammal. Symptoms are excitement, aggressiveness & madness followed by paralysis and death.

Back 82

rabies

Front 83

During depolarization, what moves out.

Back 83

potassium moves out

Front 84

Order of action potential

Back 84

1. Potassium channels open
2. Membrane is depolarized
3. Sodium ions diffuse inward
4. Repolarization of membrane