2.1 Histology of Nervous Tissue

Question 1

Central Nervous System

Answer 1

Brain and Spinal Cord; contains 85 billlion neurons

Question 2

Peripheral Nervous System

Answer 2

All nerves outside CNS; include nerves, ganglia, enteric plexuses, and sensory receptors

Question 3

Nerve

Answer 3

A bundle of 100-1000 axons + associated connective tissue and blood vessels

Question 4

Pairs of Cranial Nerves;

Spinal nerves?

Answer 4

12;

31

Question 5

Ganglia

Answer 5

small masses of nervous tissue located outside the CNS; consists primarily of neuron cell bodies

Question 6

Enteric plexuses

Answer 6

network of neurons located in the GI walls

Question 7

Sensory receptor

Answer 7

monitors changes in external and internal env

Question 8

PNS is divided into:

Answer 8

Somatic nervous system (SNS)
Autonomic nervous system (ANS)
Enteric nervous system (ENS)

Question 9

SNS consists of:

Answer 9

sensory neurons - convey info to CNS from somatic receptors

motor neurons - conduct impulses for CNS to skeletal muscles only

Question 10

ANS consists of

Answer 10

sensory nueron - convey info to CNS from autonomic sensory receptors

motor nuerons - conduct nerve impulses from CNS to smooth muscle, cardiac muscle, and glands

Note: it is usually involuntary

Question 11

Motor part of ANS

Answer 11

Sympathetic division

Parasympathetic division

Question 12

Functions of the nervous system

Answer 12

Sensory: detect internal stimuli
Integrative: process sensory info
Motor: may elicit appropriate response by activating effectors

Question 13

Two types of cells in nervous tisse

Answer 13

Neurons and Neuroglia

Question 14

Neuroglia

Answer 14

support, nourish, and protects neurons, and maintains the interstitial fluid that bathes them

smaller than neurons, but greatly outnumber them

Question 15

Electrical Excitability

Answer 15

The ability to respond to a stimulus and convert it into an action potential

Question 16

Stimulus

Answer 16

any change in the env that is strong enough to start an action potential

Question 17

Action Potential / Nerve Impulse

Answer 17

electrical signal; propagates along the surface of the neuron membrane;
travels rapidly at constant strength

Question 18

Parts of a nueron

Answer 18

Cell body, dendrites, and an axon

Question 19

Cell body / Perikaryon / Soma

Answer 19

contains a nucleus surrounded by cytoplasm that includes typical cellular organelles

Question 20

Nissl bodies

Answer 20

sites of protein synthesis

used to replace cellular components of neurons and to regenerate damaged axon

Question 21

neurofibrils

Answer 21

provide cell shape and support

made of bundles of intermediate filaments

Question 22

Microtubules

Answer 22

moves materials between cell body and axon

Question 23

Lipofuscin

Answer 23

A product of neuronal lysosomes that accumulates as the neuron ages, but does not harm the neuron

Question 24

Nerve fiberPikac

Answer 24

general term for any neural extension that emerges from a its cell body

Two kinds of processes: an axon or many dendrites

Question 25

Dendrites

Answer 25

receiving or input portions of a neuron its plasma membrane contains many receptor sites for binding chemical messengers usually short, tapering, and highly branches

Question 26

Axon

Answer 26

propagates nerve impulses towards another neuron, muscle fiber, or gland cell contains mitochondira, microtubules, neurofibrils, but no Rough ER so no protein synthesis

Question 27

Axon hillock

Answer 27

cone-shaped elevation where the axon joins the cell body

Question 28

Initial segment

Answer 28

part of the axon closest to the axon hillock

Question 29

Trigger zone

Answer 29

area where the nerve impulses arise at the junction of the axon hillock and the initial segme3nt

Question 30

Axoplasm and Axolemma

Answer 30

Cytoplasm of an axon; | Plasma membrane of axon

Question 31

Axon collaterals

Answer 31

side branches along the length of an axon

Question 32

axon terminal / axon telodendria

Answer 32

fine processes in which the axon and its collaterals divide into and end

Question 33

synapse

Answer 33

site of communication between two neurons or between a neuron and an effector cell

Question 34

slow axonal transport

Answer 34

supplies new axoplasm to developing or regenerating axons; replenishes axoplasm in growing and mature axons conveys axoplams in one direction only; moves materials about 1-5 mm per day

Question 35

Fast axonal transport

Answer 35

moves membrane vesicles and other cellular materials from the axon terminals to the cell body to be degraded or recycled moves materials in both directions (200-400mm per day) uses proteins that function as "motors"

Question 36

Neuron classification acc. to structure

Answer 36

Multipolar neurons: several dendrites, one axon Bipolar Neurons: one main dendrite, one axon Unipolar neurons: dendrites and one axon are fused together; more appropriately called pseudounipolar neurons

Question 37

Neuron classification acc. to function

Answer 37

Sensory (Afferent) Motor (Efferent) Interneurons

Question 38

Sensory / Afferent neurons

Answer 38

either contain sensory receptors at their distal ends OR are located just after sensory receptors that are separate cells; most are unipolar in structure

Question 39

Motor / Efferent neurons

Answer 39

convey action potentials AWAY from the CNS to effectors Multipolar in structure

Question 40

Interneurons / Association neurons

Answer 40

mainly located within the CNS between sensory and motor neurons most are multipolar in structure

Question 41

Types of neuroglia

Answer 41

CNS: astrocytes, oligodendrocytes, microglia, and ependymal cells PNS: Schwann cells and satellite cells

Question 42

Astrocytes

Answer 42

star-shaped cells that have many processes and are the largest and most numerous of all neuroglia

Question 43

Function of astrocytes

Answer 43

Functions: support neurons maintain the unique selective permeability of the endothelial cells (blood-brain barrier) regulate the growth, migration, and interconnection among neurons in the brain maintain chemical env for generation of nerve impulses influences formation of neural synapse

Question 44

Oligodendrocytes

Answer 44

look like astrocytes but are smaller and have fewer processes forms and maintains the myelin sheath around CNS axons

Question 45

Myelin sheath

Answer 45

multilayered lipid and protein covering around axons that insulate them and increase the speed of nerve impulse conduction

Question 46

Microglial cell / Microglia

Answer 46

``` small cells with spine-like projections function as phagocytes that remove cellular debris , damaged nervous tissue, or microbes ```

Question 47

Ependymal cells

Answer 47

produce, monitor and assist the circulation of cerebrospinal fluid single layer of columnar or cuboidal cells that possess microvilli and cilia

Question 48

Schwann cells

Answer 48

form the myelin sheath around axons; one cell can only myelinate one axon participate in axon regeneration, easier to do in PNS than CNS

Question 49

Satellite cells

Answer 49

provide structural support regulate the exchanges of material between neuronal cell bodies and interstitial fluid

Question 50

ganglion

Answer 50

cluster of neuronal cells bodies in the PNS

Question 51

nucleus

Answer 51

cluster of neuronal cells bodies in the CNS

Question 52

nerve

Answer 52

bundle of axons located in the PNS

Question 53

tract

Answer 53

bundle of axons located in the CNS

Question 54

White matter

Answer 54

composed primarily of myelinated axons

Question 55

gray matter

Answer 55

contains neuronal cell bodies, dendrites, unmyelinated axons, axon terminals and neuroglia