lecture 19 - nerve tissue histology

Question 1

What are the histological features of a soma nucleus?

Answer 1

Pale (euchromatic), spherical, central

Question 2

What are the organelle features of a neurone soma?

Answer 2

rich in rER and sER to prodcue proteins, nissl bodies, neuronal cytoskeleton

Question 3

What is the name for aggregations of ER in a neurone soma?

Answer 3

Nissl bodies

Question 4

What part of a neurone contains mitochondria?

Answer 4

All parts

Question 5

What part of a neurone is involved in the afferent signalling system?

Answer 5

dendrite

Question 6

What part of a neurone is involved in the efferent signalling system?

Answer 6

Axon/axon terminal

Question 7

What type of axodendritic connections do dendrites receive?

Answer 7

Both excitatory and inhibitory

Question 8

Where does the axon of a neurone start?

Answer 8

At the axon hillock

Question 9

How can the axon hillock be identified based on organelles present/absent?

Answer 9

It is a region free from nissl bodies

Question 10

What is the name for the expansions at terminal parts of axons?

Answer 10

Presynaptic boutons

Question 11

What are the types of macroglia cells in the CNS?

Answer 11

Astrocytes, oligodendrocytes

Question 12

What are the functions of astrocytes?

Answer 12

energy store, maintain/regulate synapses, help form blood-brain barrier

Question 13

What is the function of oligodendrocytes?

Answer 13

myelinate CNS axons

Question 14

How many axon segments can a single oligodendrocyte myelinate?

Answer 14

Up to 50

Question 15

What are microglia?

Answer 15

Antigen presenting immune cells of the CNS

Question 16

How do astrocytes regulate the blood brain barrier?

Answer 16

By changing permeability/constriction of blood vessels in the brain

Question 17

What is the distribution of schwann cells in realtiob to axons?

Answer 17

Found along axons in longitudinal chains

Question 18

What are the roles of schwann cells apart from myelination?

Answer 18

facilitation of axonal regrowth following acute nerve injury.

Question 19

What is a myelin sheath made up of?

Answer 19

Tightly wrapped spiral of lipid-rich cell membrane of schwann cells (PNS) or oligodendrocytes (CNS)

Question 20

How does the wrapping of the myelin sheath occur?

Answer 20

Wrapping proceeds from outside to inside, starting with a portion of the axon.

Question 21

How are Schwann cells involved with unmyelinated axons?

Answer 21

They envelope multiple axons, but do not wrap them in myelin

Question 22

What is the internode of an axon?

Answer 22

A territory myelinated by an oligodendrocyte or Schwann cell, between 2 nodes of ranvier

Question 23

What is a node of ranvier?

Answer 23

An interval between two myelinated internodes of an axon

Question 24

How are nodes of ranvier important in propagating action potentials?

Answer 24

They have ion pumps for exchanging sodium and potassium ions across membrane to help in propagating depolarisations

Question 25

What are the 3 main connective tissue sheaths of nerve tissue?

Answer 25

Epineurium, perineurium, endoneurium

Question 26

What is the epineurium of peripheral nerves connected to surrounding tissues by?

Answer 26

Mesoneurium

Question 27

What is the mesoneurium of nerves?

Answer 27

Connective tissue that joins peripheral nerves to outside structures, and contains nerve segmental blood supply

Question 28

What encloses a ganglion?

Answer 28

Fibrous connective tissue

Question 29

What type of neurone make up the dorsal root ganglia?

Answer 29

Unipolar/pseudounipolar, with both myelinated and unmyelinated axons

Question 30

What part of a neurone is invovled in a ganglioin?

Answer 30

Soma

Question 31

What sheath surrounds the soma in the dorsal root ganglion and provides structural and metabolic support?

Answer 31

Satellite glial cells

Question 32

What type of neurone make up autonomic ganglia?

Answer 32

Multipolar neurons

Question 33

What are the histological differences between autonomic and dorsal root ganglia?

Answer 33

autonomic have fewer satellite glial cells, and the neurones soma are more widely spaced as they are separated by dendrites and other axons. dorsal root ganglia are unipolar while autonomic are multipolar

Question 34

What are the 2 types of sensory receptor nerve endings?

Answer 34

free nerve endings, encapsulated nerve endings

Question 35

What are the 5 key types of encapsulated nerve endings?

Answer 35

meissner’s corpuscles, pacinian corpuscles, ruffini endings, neuromuscular spindle, golgi tendon organs

Question 36

Where are golgi tendon organs found?

Answer 36

Near a musculotendinous junction between a muscle and tendon

Question 37

What stimuli will activate golgi tendon organs?

Answer 37

Passive stretch/tension in tendon, active contraction of muscle

Question 38

What is the function of golgi tendon organs?

Answer 38

They provide proprioceptive information about musculotendinous junctions