Lecture 24 - The Nervous System And Neuroglia

Question 1

Functions of the nervous system

Answer 1

Gathering sensory input from sensory receptors (take in info)

Processing and interpreting sensory input to decide on appropriate response - integration (analyze info)

Using motor output to activate effector organs, muscles and glands to cause a response (produce response)

Question 2

The central nervous system

Answer 2

Brain and spinal chord
Control centre that interprets sensory input and dictates motor output

Question 3

Peripheral nervous system

Answer 3

Portion on nervous system outside CNS

Consists mainly of nerves that extend from brain and spinal chord

Question 4

Divisions of peripheral nervous system

Answer 4

Sensory (afferent) division

Somatic sensory fibres

Visceral sensory fibres

Motor (efferent) division

Question 5

Sensory (afferent) division

Answer 5

carries impulses toward the central nervous system from sensory receptors located throughout the body

Question 6

Somatic sensory fibres

Answer 6

Convey impulses from skin, skeletal muscles and joints to the CNS

Question 7

Visceral sensory fibres

Answer 7

carry impulses from organs within the ventral body cavity

Question 8

Motor (efferent) division

Answer 8

transmits impulses from the CNS to effector organs, such as muscles and glands. It has two subdivisions.

Question 9

Motor (efferent) division of PNS- Somatic nervous system

Answer 9

Consists of somatic motor nerve fibres that conduct impulses from the CNS to skeletal muscles and allow conscious (voluntary) control of motor activities.

Question 10

Motor (efferent) division of PNS- autonomic nervous system

Answer 10

an involuntary system consisting of visceral motor nerve fibres that regulate the activity of smooth muscle, cardiac muscle, and glands.

Two subdivisions, sympathetic- mobilizes body systems during activity
parasympathetic- rest and relaxation, conserves energy

Question 11

Neurons

Answer 11

Nerve cells

Excitable cells that transmit electrical signals

Question 12

Neuroglia

Answer 12

Glial cells

Small cells that protect neurons and help them to function

Question 13

Four main Neuroglia of CNS

Answer 13

Astrocytes

Microglial cells

Oligodendrocytes

Ependymal cells

Question 14

Astrocytes

Answer 14

regulate the chemical environment around neurons and play a role in exchanges between neurons and capillaries.

Most abundant,versatile and highly branched glial cells

Support and guide young neurons

Respond to nerve impulses

Etc.

Question 15

Microglial cells

Answer 15

Monitor health and perform defence functions for neurons

Small,ovoid cells with thorny processes that touch and monitor neurons

Migrate toward injured neurons

Transform to phagocytize microorganisms and neuronal debris

Question 16

Oligodendrocytes

Answer 16

Branched cells that wrap around CNS neuron fibres, forming insulating myelin sheath in thicker nerve fibres

Each oligodendrocyte can insulate dozens of nearby axons

Question 17

Ependymal cells

Answer 17

Line the central cavities of brain and spinal cord and help circulate cerebrospinal fluid

Question 18

Satellite cells

Answer 18

Surround neuron cell bodies

Function similarly to Astrocytes, but are in PNS

Question 19

Schwann cells

Answer 19

Surround all peripheral nerve fibres and form myelin sheaths in thicker nerve fibres

Perform similar function as Oligodendrocytes

Vital to regeneration of damaged peripheral nerve fibres

Question 20

Myelin sheath

Answer 20

a lipid-rich sheath of plasma membrane that wraps around part of axon and facilitates the transmission of electrical signals.

Proteins in the myelin help to hold the wrap together.

Question 21

Axons and insulation

Answer 21

In CNS insulated by Oligodendrocytes

In PNS by Schwann cells

Question 22

Myelin sheaths of PNS

Answer 22

formed by Schwann cells that wrap themselves around axon

have gaps called nodes of ranvier

Protect and electrically insulate axons (myelinated fibres) and increase the speed of nerve impulse transmission

Question 23

Nodes of ranvier

Answer 23

Gaps in myelin sheath where axon collaterals can emerge

Question 24

Non myelinated fibres

Answer 24

Do not contain sheath and conduct impulses more slowly

Question 25

Myelin sheath in CNS

Answer 25

formed by oligodendrocytes

Myelin sheath gaps are present

Question 26

White matter

Answer 26

Regions of brain and spinal cord with dense collections of myelinated fibres, usually fibre tracts

Question 27

Grey matter

Answer 27

Mostly neuron cell bodies (soma) and non myelinated fibres