L18 The Nervous System And Its Cells

Question 1

What is the Central Nervous System?

Answer 1

Sensory and motor signals are combined and coordinated, consciousness, memory, and emotion manifests.
Includes: brain and spinal cord

Question 2

What is the Peripheral Nervous System

Answer 2

• All the nervous tissue outside the brain and spinal cord, like sensory receptors and peripheral nerves.
• Communication between CNS and body

Question 3

What does the peripheral nervous system divide into?

Answer 3

1) Afferent division
2) Efferent division

Question 4

What is Afferent division?

Answer 4

• Comunicates incoming sensory signals to CNS
• Composed of sensory neurons

Question 5

What do sensory neurons monitor?

Answer 5

Somatic and visceral stimuli (External and Internal)

Question 6

What is Efferent Division?

Answer 6

• Communicates outgoing motor signals
• Composed of motor neurons

Question 7

What signals do motor neurons send?

Answer 7

Send somatic signals and autonomic signals

Question 8

What does the Autonomic nervous system do?

Answer 8

Controls involuntary responses

Question 9

What does the Somatic nervous system do

Answer 9

Controls voluntary movement

Question 10

Which effectors receive somatic signals?

Answer 10

To voluntary effectors (skeletal muscle)

Question 11

Which effectors receive autonomic signals?

Answer 11

Involuntary effectors (smooth, cardiac muscles, and glands)

Question 12

What are autonomic signals divided into?

Answer 12

Signals
1) Sympathetic (fight or flight - mobilises body systems)
2) Parasympathetic (rest and digest - conserves energy)

Question 13

What are the major functions of the nervous system?

Answer 13

1) Monitor internal and external environments
2) Integrate(Combine) sensory information
3) Coordinate responses from all organ systems

Question 14

What are the major cell types of the nervous system

Answer 14

1) Neurons
2) Neuroglial cells

Question 15

What are neurons responsible for?

Answer 15

Neurons are building blocks of the nervous system. They transmit electrical signals (action potentials) to communicate and coordinate body functions.

Question 16

What are the 3 major cellular structures of the neurons?

Answer 16

1) Cell body
2) Dendrites
3) Axon(s)

Question 17

What does the cell body contain?

Answer 17

• Major organelles
• Rough ER (Nissl bodies)
• Grey matter (because of rough ER)

Question 18

What is the role of dendrites?

Answer 18

Monitor external and internal sensory stimuli

Question 19

What is within the Axons?

Answer 19

• Axon hillock (absence of Nissl bodies)
• Collaterals (branching)
• Axon termini (ends of branching and synapse onto other neurons or effectors)

Question 20

What is the direction of the action potential ?

Answer 20

1) Dendrites
2) Cell body
3) Axon

Question 21

What happens to the centrioles of neurons?

Answer 21

Disappear at around 1 y.o, making cell division impossible afterwards

Question 22

What do we call the axon plasma membrane?

Answer 22

Axolemma

Question 23

What do we call the cytoplasm of the axon?

Answer 23

Axoplasm (does not apply to dendrites or cell body)

Question 24

What are the 3 shapes of neurons?

Answer 24

1) Multipolar
2) Unipolar
3) Bipolar

Question 25

What are multipolar neurons?

Answer 25

- Found in the CNS - Multiple projections (dendrites) leave cell body - Their Axons leave brain or spinal cord and can connect to other neurons or effectors

Question 26

What are Unipolar neurons?

Answer 26

- Sensory neurons with one projection - Dendrites detect stimuli - Axon sends signals to CNS - Single projection leaves cell body

Question 27

What are Bipolar neurons?

Answer 27

- Rare - Eyes, ears, and olfactory bulbs - One dendrite and one axon connected to the cell body

Question 28

What is the characteristics of sensory neurons by their function?

Answer 28

- Afferent - Collect sensory info & transport them to CNS - Unipolar and rarely bipolar

Question 29

What is the classification of motor neurons and there function?

Answer 29

- Efferent - Transmit info to PNS from CNS - Multipolar

Question 30

What is the characteristics of association or interneurons and there function?

Answer 30

- Connect neurons in CNS - Multipolar

Question 31

What are the characteristics of afferent neurons?

Answer 31

- Receive sensory info - Receive external and internal environment info - Carry signals towards brain or spinal cord to synapse on neurons in CNS - Unipolar - Cell bodies cluster into ganglia

Question 32

Characterstics of efferent neurons

Answer 32

- Synapse onto effector cells (muscles and glands) - Carry info away from brain and spinal cord - Multipolar - Cell bodies clustered into grey matter of CNS - Axons exit into PNS

Question 33

What are the characteristics of interneurons?

Answer 33

- Most abundant neurons - Found in CNS only - Connect neurons to each other (sensory and motor) - Complex stimuli transmited along more interneurons to manifest the brains higher functions

Question 34

What are the different type of neuroglia and which system are they in?

Answer 34

CNS - Astrocytes - Oligodendrocytes - Microglia - Ependymal cells PNS - Satellite cells - Schwan cells

Question 35

What is the organization of cells in the nervous tissue?

Answer 35

In Gray matter - Cell bodies - Dendrites - Axons of neurons In White matter - Axons of neurons Neuroglia present in both matter types

Question 36

What are the characteristics of the astrocytes neuroglia? (CNS)

Answer 36

- Largest and most numerous in CNS - Create 3D framework in nervous tissue - Nervous tissue repair - Maintain blood brain barrier (BBB) by wrapping their processes around the capillaries

Question 37

What does BBB do?

Answer 37

- Filters blood to limit what reaches brain and spinal cord - Creates unique interstitial fluid in nervous tissue

Question 38

What are the characteristics of the oligodendrocytes neuroglia? (CNS)

Answer 38

- Myelin sheath (wrap their plasma membranes around axons) - Each oligodendrocyte wraps around multiple axons, forming myelin for several neurons.

Question 39

What does myelin do?

Answer 39

- Lipid rich - Insulates axons to speed up electrical transmission by preventing ion loss - Makes up most of white matter

Question 40

What are the characteristics of microglia neuroglia? (CNS)

Answer 40

- Smallest and least common - Phagocytic - Protect against chemical and infectious agents by englufing wastes, pathogens, and debris

Question 41

Why are microglia important?

Answer 41

- CNS is an immune privileged zone, inflammation not included - inflammation in the CNS causes swelling, but the brain and spinal cord are enclosed in bone with no room to expand.

Question 42

What are the characteristics of the ependymal cells? neuroglia CNS

Answer 42

- Line cavities that carry cerebrospinal fluid Ex: central canal of the spinal cord and ventricles (chambers of the brain - Create, monitor and circulate cerebrospinal fluid via cilia

Question 43

Cancer... What types of tumours can we find in the CNS?

Answer 43

1) Primary tumours 2) Secondary CNS tumours

Question 44

What is a primary tumour?

Answer 44

- Tumours originating in CNS - In adults: abnormal neuroglial cell division Why? because neurons cease cell division at ~1y.o - Found typically in young children

Question 45

What is secondary CNS tumours?

Answer 45

- Metastasis of other cancers - Cell appear and behave as those of the parent tissue

Question 46

What are the characteristics of Satellite cells neuroglia? (PNS)

Answer 46

- Surround & support cell bodies of unipolar neurons in PNS (found in ganglia) - Mirror function of astrocytes

Question 47

What are the characteristics of Schwann cells neuroglia? PNS

Answer 47

- Cover all axons in PNS (mirroring the oligodendrocytes) - Surrounds ONLY short stretch of axon - Along unmyelinated axons wrap their cell membranes around one or more axons - Along myelinated axons myelin sheat occurs in many layers