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General - Anatomy🫀 > L8: Organization of nervous system > Flashcards

L8: Organization of nervous system Flashcards

1
Q

What is the nervous system composed of?

A

The nervous system is formed of 2 types of cells and their processes:

 Nerve cells: called neurons.

 Supporting cells: called glial cells or neuroglial cells or neuroglia.

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2
Q

What is the structure of the cell body (soma)?

A

consists of the nucleus and cytoplasm.

 The nucleus is usually central and contains nucleolus.
 The cytoplasm contains organelles & inclusions

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3
Q

What are the processes of the nerve cell?

A

single axon and dendrites.

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4
Q

Compare between axon and dendrites Acc to:

Length
Function

A

 It is the largest process of the nerve cell
 Through which the nerve cell communicates with other nerve cells

 Short and highly branched processes
 Receive impulses from other neurons and transmit them toward the cell body

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5
Q

What are neurons classified according to?

A

the number of their processes into 3 types:

1) Unipolar Neurons: they have one process:
a. True unipolar neurons
b. Pseudounipolar neurons

2) Bipolar Neurons: 2 processes, one axon, and one dendrite. located in the sense organs (olfactory epithelium of nose, retina)

3) Multipolar Neurons: one axon and several dendrites. They form most of the nerve cells in the nervous system

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6
Q

What are synapses?

A

Sites of communication between nerve cells or between a nerve cell and muscle or gland.

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7
Q

What is the structure of the synapse?

A
  1. Presynaptic element: axon terminal containing synaptic vesicles.
  2. Synaptic cleft: 20-nm space.
  3. Postsynaptic element: usually dendrite.
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8
Q

What are the types of synapses?

A

1) Axodendritic synapse: between axon and dendrite.
2) Axonaxonic synapse: between axon and axon.
3) Axosomatic synapse: between axon and cell body.
4) Neuromuscular junction: between axon and muscle fiber

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9
Q

What are the types of neuroglia cells

A

A. CENTRAL NEUROGLIA: in the central nervous system(CNS)

B. PERIPHERAL NEUROGLIA: in the peripheral nervous system

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10
Q

What are examples of central neuroglia?

A

a. Astrocytes: for support and protection.
b. Oligodendrocytes: for the formation of myelin.
c. Microglia: for phagocytosis and defense against infection.
d. Ependymal cells: lining ventricles of the brain

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11
Q

What are examples of peripheral neuroglia?

A

a. Schwann cells: formation of myelin
b. Satellite cells: surrounding nerve cells

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12
Q

What are the divisions of the NS?

A

1) Central nervous system (C.N.S): Brain Spinal cord
2) Peripheral somatic nervous system
3) Peripheral autonomic nervous system

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13
Q

What are the divisions of the brain?

A

1) Cerebrum: formed of:
a. Two cerebral hemispheres: contain higher motor and sensory centers.
b. Diencephalon: formed mainly of thalamus and hypothalamus

2) Cerebellum: for coordination of muscles movements and maintaining equilibrium.

3) Brain stem: formed of the midbrain, pons, and medulla oblongata.

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14
Q

What is another division of the brain?

A

Forebrain: two cerebral hemispheres and diencephalon

midbrain: midbrain

hindbrain: cerebellum, pons, and medulla

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15
Q

What are the ventricles of the brain?

A

 Lateral ventricle in each cerebral hemisphere
 3rd ventricle in the diencephalon
 4th ventricle in the hindbrain

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16
Q

What is the length of the spinal cord?

A

Length: 45 cm in the male and 42 cm in the female.

17
Q

What is the location of the spinal cord?

A

in the upper two-thirds of the vertebral canal.

18
Q

Where does the spinal cord begin?

A

as the continuation of the medulla oblongata.

19
Q

Where does the spinal cord end?

A

It ends at:

o In the newborn: at the level of the third lumbar vertebra (L3).

o In the adult: at the level of the lower border of (L1).

20
Q

What is the number of spinal cord segments?

A

31 segment

21
Q

What is the distribution of spinal nerves?

A

Distribution: the 31 pairs of the spinal nerves are distributed as follows:

 8 cervical  12 thoracic  5 lumbar  5 sacral  1 coccygeal

22
Q

How are spinal nerves formed?

A
  • Each spinal nerve arises by 2 roots
  • The 2 roots unite at the intervertebral foramen to form spinal nerve trunk
23
Q

What does the ventral root contain?

A

 Axons of anterior horn cells supply skeletal muscles.
 Axons of lateral horn cells (autonomic) supply smooth muscles.

24
Q

What is attached to the dorsal root?

A

The spinal ganglion is attached to it; so it is called dorsal root ganglion.

25
Q

What is the dorsal root formed from?

A

It is formed of processes of pseudounipolar cells of the spinal ganglion

26
Q

Ventral root

A

Motor (efferent)

27
Q

Dorsal root

A

Sensory (afferent)

28
Q

What are the branches of spinal nerves?

A

Anterior (Ventral) Primary Ramus
Posterior (Dorsal) Primary Ramus

29
Q

What are the characters of ventral primary rami?

A

 Large in size.

 Run anteriorly

 May join each other to form plexuses

 Connected to the sympathetic chain

30
Q

What are the characters of dorsal primary rami?

A

 Smaller in size
 Run backward supply muscles & skin of the back.
 Does not share in the formation of plexuses.
 Not connected to the sympathetic chain

31
Q

What is attached to the sympathetic ganglion?

A

Ventral ramus is attached to sympathetic ganglion by 2 rami communicantes: white ramus (myelinated) and gray ramus (unmyelinated)

32
Q

What is the number of cranial nerves and from where do they arise?

A

 Consists of 12 pairs (I to XII).
 All arise from the brainstem except The first (I, olfactory), which arises from the nose, and the second (II, optic), which arises from the retina

33
Q

What do both of the autonomic systems consist of?

A

Each system is formed of 3 components:
 Preganglionic fibers: arise from a nucleus in the brain stem or spinal cord.
These fibers relay in the autonomic ganglia.
 Autonomic ganglia: sympathetic, or parasympathetic.
 Postganglionic fibers: arise from the ganglia to supply the organs.

34
Q

Peripheral somatic nervous system

A

 Cranial nerves: 12 pairs, from brain .

 Spinal nerves: 31 pairs, from spinal cord .

 Associated ganglia: spinal & cranial ganglia

35
Q

Peripheral autonomic nervous system

A

 Sympathetic part: thoracolumbar part .

 Parasympathetic part: craniosacral part .

 Associated ganglia: autonomic ganglia

36
Q

What are the sympathetic and parasympathetic nerves?

A

General - Anatomy🫀 (9 decks)

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