Unit 19: Nervous System

Question 1

The central nervous system (CNS) is the “command center” which includes the brain and spinal cord. It processes and and integrates information. What is the peripheral nervous system (PNS) and how does it differ from the CNS?

Answer 1

The PNS consists of the cranial nerves and the spinal nerves. There are 2 divisions:
-Sensory/afferent division~> sensory receptors that detect stimuli
-Motor/efferent division~> convey impulses away from the CNS and innervates effectors (muscles & glands)

Question 2

Explain the steps of touching a hot object and quickly withdrawing your hand

Answer 2

Sensory receptors detect the stimuli and signal the CNS, which then sends back a signal for motor neurons, which triggers the effector muscles to withdraw the hand

Question 3

What are the 2 subdivisions of the motor neurons (PNS)?

Answer 3

Somatic: skeletal muscles

Autonomic: involuntary
-Sympathetic~> fight/flight
-Parasympathetic~> rest, relaxation

Question 4

When a signal is passed through the CNS, it goes through the _______ center

Answer 4

integration

Question 5

Describe the cell body of the neuron

Answer 5

Have typical organelles
RER called - Nissi Bodies
Groups/clusters in:
-CNS = nuclei (gray matter)
-PNS = ganglia

Question 6

What do dendrites do?

Answer 6

Receive incoming messages and relay them to the cell body

Question 7

What is the axon hillock?

Answer 7

Where the axon meets the cell body

Question 8

What are Schwann cells?

Answer 8

Myelin sheath of the PNS

Question 9

Gaps in the myelin sheath are called ______ __ ______.

Answer 9

Nodes of Ranvier

Question 10

What are cells that support the neurons called?

Answer 10

Neuroglia (glial cells)

They can undergo mitosis (can cause brain tumours if uncontrolled)

Question 11

Give the 4 types of neuroglia
that serve the CNS

Answer 11

-Oligodendrocytes: produce myelin
-Microglia: protective—can become phagocytic to inject foreign particles
-Astrocytes: surround capillaries to form part of the blood brain barrier
-Ependymal: neural epithelia, secretes cerebrospinal fluid (CSF)

Question 12

Give the types of neuroglia that serve the PNS

Answer 12

Schwann cells: form myelin around axons in the PNS

Satellite cells: surround neuron cell bodies in the ganglia—protect/support

Question 13

Structural/Anatomical and Functional are types of classification for what?

Answer 13

Neurons

Question 14

In the context of neuron classification, what are the 3 types of structural/anatomical classification?

Answer 14

-Unipolar: 1 process that divides into 2: central and peripheral (peripheral end has dendrites to be sensory receptors)
-Bipolar: 2 processes~> 1 axon, 1 process with dendrites (sensory for retina&nose)
-Multipolar: >2 processes, 1 axon and many dendrites (all interneurons and motor neurons)

Question 15

The functional classification of neurons focuses on the direction of impulse conduction. What are the types?

Answer 15

Sensory/Afferent neurons: mostly unipolar, from sensory to CNS

Interneurons: within the CNS (between sensory & motor), mostly multipolar

Motor/Efferent neurons: CNS to effectors (all multipolar)

Question 16

Neuronal, neuromuscular, and neuroglandular are all types of what?

Answer 16

Neuron junctions (synapses)

Neuronal: neuron to neuron
Neuromuscular: motor neuron to skeletal muscle
Neuroglandular: motor neuron to gland

Question 17

What are the 4 parts that make up a chemical synapse between neurons?

Answer 17

Presynaptic neuron (brings impulse)
Axon terminal (has neurotransmitters)
Synaptic cleft
Postsynaptic neuron (receives impulse)

Question 18

What are 3 things that serve as protective features for the CNS?

Answer 18

Bone (skull and vertebrae)
Meninges
Cerebrospinal fluid (CSF)

Question 19

The meninges are 3 layers of protective connective tissue around the brain and spinal cord. What are the layers?

Answer 19

Dura mater (outer)
——subdural space——
Arachnoid mater (middle)
——subarachnoid space——
Pia mater (on surface of brain and SC)

Question 20

What are 2 characteristics of the dura mater layer that are different between the brain and spinal cord?

Answer 20

Brain dura mater (2 layers) is separated in some places to form venous (dural) sinuses, which contain blood

The dura mater layer of the spinal cord has the epidural space superficial to it, filled with fat, blood vessels, CT, etc.

Question 21

The arachnoid mater layer is avascular and has an area deep to it called the _______ space, which contains _______ _______, and has web-like strands of CT to secure it to the pia mater. It has _______ _______ in the brain only, which projects into the dural sinuses.

Answer 21

subarachnoid, cerebrospinal fluid, arachnoid granulations

Question 22

What is meningitis?

Answer 22

Inflammation of the meninges

Question 23

Cerebrospinal fluid (CSF) surrounds the brain and spinal cord. It is in brain ventricles and the spinal canal. What are these ventricles?

Answer 23

2 lateral (1st & 2nd)~> in cerebrum

3rd ventricle~> in diencephalon

4th ventricle~> surrounded by pons, medulla oblongata, and cerebrum