Neurons and Spinal Cord Flashcards by Ashley Thraxton

What are the three general functions of the nervous system?

Sensory, integrative, and motor

How well did you know this?

Not at all

Perfectly

What are the two major divisions of the nervous system?

The central nervous system (CNS) and the peripheral nervous system (PNS)

How well did you know this?

Not at all

Perfectly

How is the peripheral nervous system divided up?

It is divided into the somatic and autonomous nervous system

How well did you know this?

Not at all

Perfectly

What is the function of neuroglia?

They fill spaces, provide structural frameworks, produce the components of myelin, and carry out phagocytosis

How well did you know this?

Not at all

Perfectly

What are the types of neuroglia in the central nervous system?

microglial cells
oligodendrocytes
astrocytes
ependymal cells

How well did you know this?

Not at all

Perfectly

What are microglial cells?

A type of neuroglia in the CNS that support neurons and phagocytise bacterial cells, and form scars in areas of damage.

How well did you know this?

Not at all

Perfectly

What are oligodendrocytes?

A type of neuroglia in the CNS that align along nerve fibers. They provide a myelin sheath around axons within the brain and spinal cord.

How well did you know this?

Not at all

Perfectly

What are astrocytes?

A type of neuroglia in the CNS that provide structural support, join parts by their abundant cellular processes, and help regulate the concentration of nutrients and ions within the tissue. Form scar tissue that fills spaces following CNS injury.

How well did you know this?

Not at all

Perfectly

What are ependymal cells?

A type of neuroglia in the CNS that form an epithelial-like membrane that covers specialised brain parts and form inner linings that enclose spaces in the brain and spinal cord.

How well did you know this?

Not at all

Perfectly

What structure in the brain do astrocytes help form?

The blood-brain barrier

How well did you know this?

Not at all

Perfectly

What are the neuroglia in the peripheral nervous system?

Schwann cells

How well did you know this?

Not at all

Perfectly

What is chromatophilic substance? (also know as Nissl bodies)

A large granular body found in neurons. These granules are rough endoplasmic reticulum (RER) with rosettes of free ribosomes, and are the site of protein synthesis

How well did you know this?

Not at all

Perfectly

What is neurilemma?

The outermost layer of Schwann cells that surrounds the axon of the neuron. It forms the outermost layer of the nerve fiber in the peripheral nervous system.

How well did you know this?

Not at all

Perfectly

When peripheral nerves are damaged, their _____ can regenerate. The ___________ plays an important role in this process. In contrast, the ___ axons are myelinated by oligodendrocytes which do not provide a __________. Consequently, damaged CNS neurons usually do not regenerate.

When peripheral nerves are damaged, their **axons **can regenerate. The **neurilemma **plays an important role in this process. In contrast, the **CNS **axons are myelinated by oligodendrocytes which do not provide a neurilemma. Consequently, damaged CNS neurons usually do not regenerate.

How well did you know this?

Not at all

Perfectly

What are the three groups that neurons are classified into?

Multipolar neurons
Bipolar neurons
Unipolar neurons

How well did you know this?

Not at all

Perfectly

What are the main features of multipolar neurons?

many processes arising from cell bodies
only one process of each neuron is an axon, the rest are dendrites

How well did you know this?

Not at all

Perfectly

What are the main features of bipolar neurons?

have two processes, one arising from each end of the cell body
one process of an axon, the other is a dendrite

How well did you know this?

Not at all

Perfectly

What are the main features of **unipolar **neurons?

have a single process extending from cell body
the process divides into two branches which function as a single axon
there is a peripheral process and a central process

How well did you know this?

Not at all

Perfectly

The cell bodies of some _________ neurons aggregate in specialised masses of nervous tissue called _____ which are located outside the _____ and ______ _____.

The cell bodies of some **unipolar **neurons aggregate in specialised masses of nervous tissue called **ganglia **which are located outside the **brain **and spinal cord.

How well did you know this?

Not at all

Perfectly

What are the types of neuron based on their function?

sensory neurons
interneurons
motor neurons

How well did you know this?

Not at all

Perfectly

What do sensory (afferent) neurons do?

**Transmit **nerve impulses from peripheral body parts to the brain or spinal cord. They either have special receptor ends or are closely associated with receptor cells in the skin or in sensory organs.

How well did you know this?

Not at all

Perfectly

What do interneurons do?

They transmit impulses from one part of the brain or spinal cord to another

How well did you know this?

Not at all

Perfectly

What is an aggregation of the bodies of interneurons called?

A nucleus (plural nuclei). They are similar to ganglia, but in the CNS.

How well did you know this?

Not at all

Perfectly

What do motor (efferent) neurons do?

Transmit impulses out of the brain or spinal cord to effectors.

How well did you know this?

Not at all

Perfectly

What is a synapse?

A junction between any two communicating neurons

Neurons are seperated by a gap called a _______ \_\_\_\_\_.

**Synaptic celft**

What are the chemicals that transmit impulses?

neurotransmitters

Define resting potential

The difference in charge between the inside and outside of a resting nerve cell

What is the resting potential of a neuron? (mV)

-70 mV

What is the threshold potential? (mV)

-55 mV

What are the main steps in an action potential being generated?

Action potentials are normally initiated at a low threshold "\_\_\_\_\_\_\_ \_\_\_\_" that is more excitable than any other part of the dendrites. This _______ \_\_\_\_\_ is located at the axon initial segment, the \_\_\_\_\_\_\_ \_\_\_\_\_\_\_.

Action potentials are normally initiated at a low threshold "**trigger zone**" that is more excitable than any other part of the soma or dendrites. This **trigger zone** is located at the axon initial segment, the **axon hillock.**

What are sensory fibers?

Neuron processes that bring sensory information into the CNS

What are motor fibers?

Neuron processes that carry impulses from the CNS to effectors

Like neurons, nerves that conduct impulses to the brain of spinal cord are called _________ \_\_\_\_\_\_\_, and those that carry impulses to muscles or glands are termed ______ \_\_\_\_\_\_. Most nerves include both of these and are called _______ \_\_\_\_\_\_.

Like neurons, nerves that conduct impulses to the brain of spinal cord are called **sensory nerves**, and those that carry impulses to muscles or glands are termed **motor nerves**. Most nerves include both of these and are called **mixed nerves**.

What is a named example of a reflex?

*Patellar reflex*

What muscle does the patellar reflex stimulate?

The quadriceps femoris muscle group

The brain lies in the ________ \_\_\_\_\_\_\_\_ of the skull, and the spinal cord occupies the ________ \_\_\_\_\_\_ in the vertebral column.

The brain lies in the **cranial canal **of the skull, and the spinal cord occupies the **vertebral canal** in the vertebral column.

What are the three layers in **meninges**?

The **dura mater**, **arachnoid mater,** and the **pia mater**.

Describe **dura mater **

Outermost layer of the meninges. It is composed primarily of tough, white, **fibrous connective tissue** and contains many blood vessels and nerves. Dura mater continues into the vertebral canal as a strong, tubular sheath that surrounds the spinal cord. It terminates as a blind sac below the end of the cord.

Describe **arachnoid mater**

A thin, weblike membrane without blood vessels that lies between the dura and pia maters.

What is between the arachnoid and pia mater?

Subarachnoid space that contains **cerebrospinal fluid** (**CSF**)

Describe **pia mater**

A thin membrane that contains many **nerves** and **blood vessels** that **nourish** underlying cells of the brain and spinal cord. This layer hugs the surfaces of these organs and follows their irregular contours.

Define spinal cord

A slender nerve column that passes downward from the brain into the vertebral canal

How many segments are in the spinal cord?

What does each spinal segment give rise to?

A pair of **spinal nerves**

In the neck region, a thickening in the spinal cord, called the _______ \_\_\_\_\_\_\_\_\_, supplies nerves to the upper limbs. A similar thickening in the lower back, the ______ \_\_\_\_\_\_\_\_\_, gives off nerves to the lower limbs.

In the neck region, a thickening in the spinal cord, called the **cervical enlargement**, supplies nerves to the upper limbs. A similar thickening in the lower back, the **lumbar enlargement**, gives off nerves to the lower limbs.

Label:

What are the two types of tracts in the spinal cord?

Ascending and descending

How many pairs of spinal nerves are there?

Each spinal nerve is associated with the vertebra \_\_\_\_\_ it. The \_\_\_\_\_\_\_ spinal nerves are an exception, because spinal nerve \_\_ passes superior to the vertebra \_\_. Thus, although there are seven \_\_\_\_\_\_\_ vertebrae, there are \_\_\_\_\_ pairs of \_\_\_\_\_\_\_ nerves.

Each spinal nerve is associated with the vertebra **above **it. The **cervical** spinal nerves are an exception, because spinal nerve **C1** passes superior to the vertebra **C1**. Thus, although there are seven **cervical **vertebrae, there are **eight **pairs of **cervical **nerves.

How many pairs of **thoracic **nerves are there?

12: T1-T12

How many pairs of **cervical **nerves are there?

8: C1-C8

How many pairs of **lumbar **nerves are there?

5: L1-L5

How many pairs of **sacral **nerves are there?

5: S1-S5

How many pairs of **coccygeal **nerves are there?

1: Co

The lumbar, saccral and coccygeal nerves descend beyond the spinal cord, forming a structure called the \_\_\_\_\_\_ \_\_\_\_\_\_\_**.**

The lumbar, saccral and coccygeal nerves descend beyond the spinal cord, forming a structure called the **cauda equina.**

The **dorsal root** contains the cell bodies of what type of neurons?

Sensory

The **ventral root **contains the axons of which type of neuron?

Motor

Define **plexus**

A branching network of vessles or nerves

What is the **cervical plexus**?

A plexus that lies deep within the neck and form from the branches of the first four cervical nerves. Supplies the muscles and skin of the neck.

What do the **phrenic nerves **control? What nerves does it include?

Made up from C3, C4, and C5. They conduct motor impulses to the muscle fibers of the **diaphragm**.

What is the **brachial plexus**? What nerves is it made up from?

Supplies the muscles and the skin of the **arm**, **forearm**, and **hand**. Contains the lower four cervical nerves and the first thoracic nerve.

What nerves are in the **brachial plexus**?

* Musculocutaneous * Ulnar * Median * Radial * Axillary

What is the **lumbosacral plexus**?

A plexus that extends out from the lumbard region and has axons from T12 to Co extending from it. Motor and sensory axons associated with the muscles and skin of the lower abdominal wall, external genitalia, buttocks, thighs, legs, and feet.

What nerves are in the **lumbosacral plexus**?

* Obturator * Femoral * Sciatic

What are the **intercostal nerves**?

The nerves associated with breathing, T2-T11