Anatomy Lesson 10

The neuron needs a high amount of energy or ATP. The ATP is created by the ______.

mitichondria

Structurally, the most common type of neuron is the _____ neuron.

multipolar

Which of the following glial cells form a myelin sheath around axons?

- astrocyte - oligodendrocyte - ependymal cell Recall that oligodendrocytes form a protective, insulating myelin sheath by wrapping around axons in the CNS, and neurolemmocytes wrap around axons, forming a myelin sheath in the PNS.Recall that oligodendrocytes form a protective, insulating myelin sheath by wrapping around axons in the CNS, and neurolemmocytes wrap around axons, forming a myelin sheath in the PNS.Recall that oligodendrocytes form a protective, insulating myelin sheath by wrapping around axons in the CNS, and neurolemmocytes wrap around axons, forming a myelin sheath in the PNS.

Neuronal pools are also called ______.

- pathways - neuronal circuits

The factors that affect PNS regeneration are ______.

- the distance between injury and the effector organs - the amount of damage

Bipolar neurons have one axon and ______ dendrite.

1

Generally, nervous tissue is made up of ____ distinct cell types

2 - neurons and glial cells

Distinguish between the central nervous system (CNS) and peripheral nervous system (PNS). Name the structures that compromise each

2 parts of nervous system 1. CNS 2. PNS CNS - runs along the center/axis of the body - runs through the spinal cord - brain/spinal cord PNS - does not run along the spinal chord/ center (everywhere else) - cranial nerves (comes out of the brain), spinal nerves, ganglia, peripheral nerves

Explain the following ways in which neurons differ from other body cells: high metabolic rate, longevity, and inability to divide.

Characteristics of Neurons - longevity (neurons survive along time) - high metabolic rate (engines of the body/ gives action) - inability to divide (less risk of cancer)

Diagram a typical multipolar neuron, labeling the following: dendrites, cell body (soma), nucleus, axon hillock, axon, myelin sheath, nodes of Ranvier, and synaptic knobs (axon terminals). State the function of each of these structures. Explain the direction in which information flows through neurons.

Cell bodies: come out of the nucleus - 1 branch of a neuron: unipolar - more than 1 branch: multipolar dendrites: receive information (from other neurons) axon hillock: like the gatekeeper, it determines if information is necessary. Determines if the stimulus is strong enough which is action potential. axons: send another message and is covered in myelin sheath which speeds up the conduction through the neuron (nerve impulse conduction) myelin sheath: speeds up conduction nodes of ranvier: between myelin sheath, needs ions/action potential to understand the structure oligodendrocyte: attached to myelin sheath, produces oligodendrocyte axon terminal: send the neuron to a different nerve What is the correct direction of flow? dendrites to cell body to axon hillock to axon to axon terminal

(T/F) One function of the nervous system is to always respond to sensory input

False because when the nervous system evaluates information, the CNS determines whether or not a response is required

Which is not a general function of the nervous system a. transporting materials throughout the body b. collecting information c. processing and evaluating information d. responding to information e. no exception; all are general functions of the nervous system

a. transporting materials throughout the body

Describe the anatomy of a nerve, including its three connective tissue wrappings.

Nerves - cable-like bundles of axons in the PNS (bundle of axons) - endoneurium wraps individual axons - perineurium wraps axons fascicles (similar to muscles, there are individual axons, which are covered in endoneurium, in the fascicles) - epineurium wraps entire nerves superficial to deep - epinerium - perineirum - endoneurium - axon

Differentiate between sensory (afferent) neurons, motor (efferent) neurons, and interneurons.

Neuron classification (functional) - sensory (afferent) neurons - interneurons - motor (efferent) neurons

Describe the function and location of the following glial cells: astrocytes, oligodendrocytes, microglial cells, ependymal cells, satellite cells, and Schwann cells

Other than Neurons what is the other type of cell? - found in glial (glue) cells - glial: cells Cytology of Nervous tissue - neurons: excitable cells that transmit nerve impulses - glial cells: non-excitable cells that support and protect the neurons Glial cells of the CNS - astrocyte: controls the ionic environment of CNS. Induces the formation of the blood-brain barrier and only small things can pass through the blood-brain barrier. Acts as a protector. (looks like a star) This is the most abundant glial cell in the CNS. Regulates tissue fluid composition - oligodendrocyte: form myelin sheaths in CNS. it myelinates axons within CNS. Form myelin in the CNS. - Microglial cells: macrophages of CNS. like the garbage man, cleans up the cell debris. Repond to infection in the CNS. Defends against pathogens - Ependymal cell: line brain internal cavities (ventricles). The glial cell that helps to circulate cerebrospinal fluid. Produces CSF Glial cells of the PNS - satellite cell: protects cell bodies in the PNS ganglia and regulates nutrients for cell bodies in ganglia (found on top of cell bodies). Surround somas in ganglia. - Schwann cell (neurolemmocyte): myelinates axons within the PNS (surrounds the axon) oligodendrocyte vs schwann - oligodendrocyte can myelinate multiple axons while schwan can only myelinate 1 axon

Describe the basic anatomy and function of a synapse.

Synapses: A junction where information is transmitted from one neuron to the next. - function: site at which neurons communicate with other neurons, muscles or glands. Where the action potential travels down the axon and to the synaptic vesicles containing neurotransmitters and to the synaptic cleft where it binds 2 receptors at the post synaptic neuron - structure: presynaptic neuron (synaptic vesicles contain neurotransmitters); synaptic cleft), postsynaptic neurons (contains receptors)

Which of the following neurotransmitters is most common?

acetycholine

If a sensory neuron detects a painful stimulus, it will send a signal to an interneuron in the CNS for processing. This may result in a motor neuron stimulating muscle contraction, moving the body away from the painful stimulus. What are the structural classifications of the three neurons in this example? (listed in the order they appear)

Unipolar, multipolar, multipolar

Differentiate between the sensory (afferent) and motor (efferent) components of the nervous system. Include a description of the somatic sensory/motor system, visceral sensory system, and autonomic motor systems.

What is the difference between sensory and motor? - Motor = creates movement/action - sensory = senses Which one goes toward the brain? which one goes away from the brain? - motor goes away from the brain - sensory goes up to the brain and tells what to do *If it does not say sensory or motor, think if it is afferent (arrives/inflowing) or efferent (exits) sensation -> nervous system integration -> response (motor) sensation: sensory receptors detect stimuli, afferent information sent to CNS - special senses: vision (eyes), hearing (ears), taste (mouth), smell (nose), balance/equilibrium - somatic senses: Recieves information from skin. information from skin, joints, and skeletal muscles (if you poke your skin, you can feel it) - visceral: Receives information from the intestines. Information from internal organs and blood vessels *think super hero powers for special senses (super vision, super hearing, etc) Response (motor): Efferent information leaves the CNS, Effectors (muscles or glands) respond) - Somatic nervous system: innervates skeletal muscles. "voluntary" innervates ONLY skeletal muscle (ex: skeletal muscle contraction) - Autonomic nervous system: Innervates cardiac and smooth muscle. "involuntary", innervates cardiac muscle, smooth muscle, and glands (like the heart beating) (ex: cardiac muscle contraction)

Name where neuronal cell bodies and axons are found in the CNS and PNS

Where are Neuron cell bodies and axons? (Nervous tissue) - gray matter contains neurons cell bodies and dendrites (makes up cortex, CNS nuclei) - white matter: contains neurons axons and myelin sheaths (full of fat like steak and fats are made up of myelin sheaths and it covers up axons) (makes up commissure and tract) Where are Neurons cell bodies and axons? (Peripheral tissue) *picture - cell bodies are in PNS ganglia (knot) and CNS gray matter - Axons are in PNS nerves and CNS white matter (found in nerves) [where are they found] CNS - soma: gray matter - Axon: white matter PNS - Soma: ganglia - axon: nerves themselves

A synapse is a junction between ______.

a neuron and another cell

Which glial cell defends the body against pathogens?

microglial cell

Explain what is known about the following clinical issues relating to the nervous system: amyotrophic lateral sclerosis cancer (primary and secondary tumors in the CNS) multiple sclerosis axon regeneration in the PNS and CNS anencephaly spina bifida

amyotrophic lateral sclerosis - also called ALS or Lou Gehrig Disease - Degeneration of the somatic motor system - Atrophied muscles caused breathing, speaking, and swallowing difficulties because muscles degenerate - no effective treatment or cure exists cancer (primary and secondary tumors in the CNS) - primary tumors: tumors form in the meninges (meningiomas) or glial cells (gliomas) Neurons are incapable of becoming tumors because they cannot divide *in brain - Secondary tumor: Tumor forms in another site (lung, skin, or breast cancers) but spreads to the brain *outside of the brain multiple sclerosis axon regeneration in the PNS and CNS - patches of myelin in brain and spinal cord destroyed - autoimmune disease - affects 1 out of every 1000 people - symptoms: blindness (effects neurons because it is a special sense), weakness (effects motor neurons because it effects the muscles), numbness (effects somatic sensors) - This condition involves progressive demyelination of neurons in the CNS accompanied by the destruction of oligodendrocytes. As a result, the conduction of nerve impulses is disrupted, leading to impaired sensory perception and motor coordination. anencephaly - disorder at the cranial end of the neural tube - substantial or complete absence of a brain - infants rarely live longer than a few hours following birth - usually detected with prenatal ultrasound spina bifida - disorder at the caudal end of the neural tube - vertebral arch is not fully formed - may be mild (occulta) or severe (meningocele or mylomeningocele) - sufficient dietary folic acid prevents spina bifida (in prenatal vitamins) Quiz time - Disorder caused by a failure of the cranial end of the neural tube to close: anencephaly - Disorder at the caudal end of the cranial tube: spina bifida - List three types going least dangerous to most dangerous: occulta, meningocele, mylomeningocele - Degeneration of somatic motor system: ALS - symptoms of ALS: trouble breathing, speaking, muscle weakness - autoimmune disease which leads to destruction of myelin to the CNS: multiple sclerosis

A condition in which the brain is substantially missing is

anencephaly

Glial cells differ from neurons in that they

are smaller and capable of mitosis

Which glial cell helps to form the blood-brain barrier?

astrocyte

In a laboratory experiment, a neuron is observed conducting an electrical change down a long cell process toward a target cell. What portion of the neuron is being observed?

axon

A soma is another name for the ___ of a neuron

cell body

dendrites branch off of the

cell body

____ conduct information from other cells toward the neuronal cell body.

dendrites

The neural plate is a thickened region of the

ectoderm

The connective tissue wrapping of a nerve, beginning at the outermost layer, are

epineurium → perineurium→ endoneurium

Synapses occur where axons contact which of the following?

gland cells muscle cells other neurons

nervous tissue is made up of neurons and ____ cells

glial 2 distinct cell types form nervous tissue: neurons, which are excitable cells that are able to generate, transmit, and receive nerve impulses, and glial cells, which are nonexcitable cells that support and protect neurons

An action potential is also called a nerve ____

impulse, signal, or propagation

Neuronal pools are made of ____

interneurons

Explain the differences between unipolar, bipolar, and multipolar neurons

multipolar neurons: Multiple branches (most CNS neurons and ALL motor neurons. Multiple branches) - Most common type of neuron; multiple nerve cell processes extend from cell body; typically one axon and many dendrites - interneuron, motor neurons Bipolar neurons: 2 branches coming out of the body. (special senses: vision, hearing, smell, taste, and balance of equilibrium) - relatively uncommon; 2 nerve cell processes extend directly from the cell body - some special sense neurons (e.g. in the olfactory epithelium of nose, the retina of the eye) unipolar neurons: 1 branch that becomes the dendrites/axons (sensory neurons that do not contain special senses) - common type of sensory neuron; single short cell process extends directly from the cell body and looks like a T as a result of the fusion of 2 processes into one long axon - most sensory neurons (detect stimuli in the form of touch, pressure, temperature, or chemicals)

Discuss the structure and function of myelin. Draw a myelinated axon, labeling the Schwann cells or oligodendrocytes and the nodes of Ranvier.

myelin sheath (speeds up action potential) - structure: Made up of oligodendrocytes in the CNS and Shwann cells in the pNS; White, fatty coating; Nodes of Ranvier (neurofibril nodes). The gaps of the myelin sheath are places where the action potential resets. - function: supports, protects and insulates axon; increases speed of conduction

The small spaces that interrupt the myelin sheath are called ______

neurofibril nodes

The term "anaxonic" describes a neuron with ______

no axon

The neuron cell body houses both the ______ and the cytoplasm. Multiple choice question.

nucleus

The glial cell that myelinates and insulates axons within the CNS is the

oligodendrocyte

The neuroectoderm is the name for the cells that make up the neural ______.

plate

At a synapse, neurotransmitters are released by the ______ neuron.

presynaptic

Neurofibril nodes are also called nodes of ______.

ranvier

If a(n) ______ detects a painful stimulus, it will send a signal to a(n) ______ in the CNS for processing. This may result in a(n) ______ stimulating muscle contraction, moving the body away from the painful stimulus.

sensory neuron, interneuron, motor neuron

The ___________ nervous system transmits information from receptors to the CNS, while the ___________ nervous system transmits information from the CNS to the rest of the body.

sensory, motor The nervous system can be functionally organized into the sensory and motor nervous systems. The sensory nervous system transmits information from sensory receptors to the CNS, while the motor nervous system transmits information from the CNS to the rest of the body.

A damaged axon within the PNS can regenerate if ______.

some neurilemma remains The success of PNS axon regeneration depends upon 2 primary factors: 1. the amount of damage 2. the distance between the site of the damaged axon and the structure it innervates. the possible repair is decreased with an increase in either of these 2 factors

The junction between an axon and another cell is called a ______.

synapse

A typical synapse in the CNS consists of a presynaptic neuron and a postsynaptic neuron, separated by a narrow space called the

synaptic cleft

Which is not a function of the motor division of the nervous system? a. conducts output (nerve impulses) from the CNS b. transmits impulses to muscles and glands c. transmits impulses from the viscera d. voluntary control of skeletal muscle e. involuntary control of the heart

transmits impulses from the viscera

Pseudounipolar is another name for a(n) ______ neuron

unipolar

Continuous conduction of a nerve impulse occurs only along

unmyelinated axons

The ______ functional division of the nervous system transmits information from the viscera to the central nervous system.

visceral sensory division