A&P Chapter 12 Neural Tissue

Interoceptor

Monitor the digestive, respiratory, cardiovascular, urinary, and reproductive systems and provide sensations of taste, deep pressure and pain

Compare and contrast Type A, B and C nerve fibers. Be sure to discuss the information that is carried through each fiber.

Myelinated axons that carry action potentials at speeds up to 140 meters per second or over 300mph. Carry sensory information to the CNS about position, balance, and delicate touch and pressure sensations from the skin surface. Motor neurons that control skeletal muscles also send their commands over these axons smaller myelinated axons; Propagations speeds average around 18 meters per second These axons propagate action potentials at a slower pace of 1 meter per second Type B and C fibers carry information to the CNS They deliver information about temperature, pain, and general touch and pressure sensations and carry instructions to smooth muscle, cardiac muscle, glands and other peripheral effectors

Describe saltatory propagation.

Only the nodes can respond to a depolarizing stimulus The local current skips the internodes, The action potential "jumps" from node to node

Describe the two passive forces influence on maintaining the cell's resting potential.

Potassium ions tend to move out.The movement is driven by a concentration gradient

Describe how a neuron becomes depolarized.

Potassium is in the neuron

Describe how a neuron becomes repolarized.

Potassium move out of the neuron.

Adrenergic synapse

Relating to nerve cells or fibers of the autonomic nervous system that use norepinephrine as their neurotransmitter.

Node of ranvier

Small gaps of a few micrometers separate adjacent internodes

Cholinergic synapse

Synapses that release Acetylcholine

Neuron

The basic functional units of the nervous system are the individual cells called neurons

What effect does the release of potassium ions have on a cell's charge?

The cell must expend energy in the form of ATP, to bail out sodium ions that leak

Compare and contrast the structure and functions of unipolar vs. multipolar neurons

Unipolar, the dendrites and axon are continuous, basically fused and the cell body lies off to one side; most sensory neurons of the peripheral nervous system are unipolar. Multipolar neurons, have two or more dendrites and a single axon; the most common type of neuron in the CNS; all the motor neurons that control skeletal muscles are multipolar

Describe the structure and function of the myelin sheath

a lipid layer formed from certain neuroglia that surrounds an axon, providing insulation.

Ganglia

a structure containing a number of nerve cell bodies, typically linked by synapses, and often forming a swelling on a nerve fiber

Sensory neuron

aka afferent neurons deliver information from the sensory receptors to the CNS (info to CNS) • Ganglia • Exteroceptors • Proprioceptors • Interoceptors

Interneuron

are responsible for the distribution of sensory information and the coordination of motor activity; Interneurons are also involved with all higher functions, such as memory, planning and learning

Microglia

are the least numerous and smallest. They act as moving (macrophages) police force and janitorial service, engulfing cellular debris waste products and pathogens.

Compare and contrast oligodendrocyte with schwann cell

cell of the peripheral nervous system that wraps around a nerve fiber and forms the myelin sheath and glial cell similar to an astrocyte but with fewer protuberances, concerned with the production of myelin in the central nervous system

Neurotransmitters

chemical that an axon secretes that stimulates or inhibits an effectors or other neurons

Nissl bodies

clusters of RER and free ribosomes account for the gray color of areas containing neuron cell bodies - the gray matter

Describe the charge inside the cell membrane vs outside.

. Thus the activity of the exchange pump exactly balances the passive forces of diffusion

Postsynaptic cell

describes a nerve cell that receives signals transmitted across a synapse from another nerve cell

Neurofilament

function primarily to provide structural support for the axon and to regulate axon diameter.

Bipolar neurons

have two distinct processes one dendritic process that branches extensively at its distal tip and one axon with the cell body between them. They relay information about sight, smell, or hearing

Multipolar neurons

have two or more dendrites and a single axon; the most common type of neuron in the CNS; all the motor neurons that control skeletal muscles are multipolar

ependymal cells

is a narrow passageway in the spinal cord is called the central canal. In the brain, the passageway forms enlarged chamber called ventricles. The central canal and ventricles are lined by a cellular layer of epithelial cells called the ependyma and are filled with cerebrospinal fluid (CSF). The ependyma consists of ependymal cells which are cuboidal to columnar in sectional view. In a few parts of the brain specialized ependymal cells participate in the secretion of the CSF. Ependymal cells have slender processes that branch extensively and make direct contact with neuroglia in the surrounding neural tissue

Action potential

is an electrical impulse that is propagated across the surface of the membrane and that does not diminish as it moves away from its source

Describe the peripheral nervous system:

is the part of the nervous system that consists of the nerves and ganglia on the outside of the brain and spinal cord.[1] The main function of the PNS is to connect the central nervous system (CNS) to the limbs and organs, essentially serving as a communication relay going back and forth between the brain and the extremities

Interoceptors

monitor the digestive, respiratory, cardiovascular, urinary, and reproductive systems and provide sensations of taste, deep pressure and pain

Proprioceptor

monitor the position and movement of skeletal muscles and joints

Proprioceptorss

monitor the position and movement of skeletal muscles and joints

Anaxonic

nerons are small, and have no anatomical features that distinguish dendrites from axons, they are located in the brain and in special sense organs

Afferent Division

of the PNS brings sensory information to the CNS from the receptors in peripheral tissues and organs

Efferent Division

of the PNS carries motor commands from the cns to the muscles and glands

Describe the autonomic nervous system

part of the nervous system responsible for control of the bodily functions not consciously directed, such as breathing, the heartbeat, and digestive processes

Describe the somatic nervous system

part of the nervous system that serves the sense organs and muscles of the body wall and limbs, and brings about voluntary muscle activity

Exteroceptor

provide information about the external environment in the form of touch, temperature, or pressure sensations and the more complex senses of sight, smell, and hearing

Exteroceptors

provide information about the external environment in the form of touch, temperature, or pressure sensations and the more complex senses of sight, smell, and hearing

Presynaptic cell

relating to or denoting a nerve cell that releases a transmitter substance into a synapse during transmission of an impulse

Internode

relatively large areas of the axon that are wrapped in myelin

Perikaryon

surrounding cytoplasm contains organelles that provide energy and synthesize organic materials especially the chemical neurotransmitters that are important in cell-to-cell communication

Effector

target organs, which respond by doing something. Somatic Nervous System- controls skeletal muscle contractions. Voluntary contractions are under conscious control. Atonomic Nervous System- provides automatic regulation of smooth muscle, cardiac muscle, and grandular secretions at the subconscious level

Describe the central nervous system

the complex of nerve tissues that controls the activities of the body. In vertebrates it comprises the brain and spinal cord

Unipolar

the dendrites and axon are continuous, basically fused and the cell body lies off to one side; most sensory neurons of the peripheral nervous system are unipolar

Name five important neurotransmitters

1. Acetylcholine 2. Excitatory 3. Dopamine 4. Norepinephrine 5. Serotonin

The sodium potassium pump exchanges _____ potassium ions for ____ sodium ions.

2 potassium ions for 3 sodium ions

Axon

A long cytoplasmic process- capable of propagating an electrical impulse known as and action potential

Compare and contrast neuromuscular, neuroglandular and neuron-neuron synapses

A synapse between a neuron and a muscle cell; a neuron controls or regulates the activity of a secretory gland; when one neuron communicates with another, the synapse may occur on a dendrite, on the cell body, or along the length of the axon of the receiving cell

Graded potential

A typical stimulus produces a temporary, localized change in the resting potential which decreases with distance from the stimulus

Compare and contrast a graded potential vs action potential

A typical stimulus produces a temporary, localized change in the resting potential which decreases with distance from the stimulus; electrical impulse that is propagated across the surface of the membrane and that does not diminish as it moves away from its source

Propagation

Action potential is relayed from one location to another in a series of steps

Describe the resting potential aka transmembrane potential. How is it maintained?

All neural activities begin with a change in the resting potential of a neuron.A typical stimulus produces a temporary, localized change in the resting potential which decreases with distance from the stimulus, this is called a graded potential

Neuroglia

Are suporting cells that separate and protect the neurons, provide a supportive frameworks for neural tissue, act as phagocytes, and help regulate the compostion od interstitial fluid

Neurofibrils

Fine, cytoplasmic thread that extends from the cell body into the processes of a neuron; bundles of neurofilaments extend into the dendrites and axon providing internal support

Describe the three states of a gated channel.

Closed, Open, Closed and incapable of opening

Compare and contrast the functions of the potassium and sodium channels and the sodium potassium exchange pumps. What is the function of each of these in maintaining the resting potential?

Depolarization results from the influx of Na+ .,Repolarization involves the loss of K+. Needs energy in the form of ATP

Motor neuron

Form the efferent division of the PNS.These neurons carry instructions from the CNS to the peripheral effectors in a peripheral tissue, organ or organ system (exit out of CNS)The two major efferent systems are the somatic nervous system and the autonomic nervous system • innervate skeletal muscles, you have conscious control of over the activity of the SNS. • The ANS innervates smooth muscle, cardiac, glands and adipose tissue throughout the body,involuntary

Describe the refractory period.

From the time an action potential begins until the normal resting potential has stabilized. The membrane cannot respond to further stimulation because all the voltage regulated sodium channels either are already open or are inactivated. The relative refractory period begins when the sodium channels regain their normal resting condition and continues until the transmembrane potential stabilizes at resting levels.

Describe the synapse

Functional connection between the axon of a neuron and the dendrite or cell body of another neuron or the membrane of another cell type

Synapse

Functional connection between the axon of a neuron and the dendrite or cell body of another neuron or the membrane of another cell type

• Astrocytes

Are the largest and most numerous neuroglia in the CNS. Astrocytes have a variety of functions: Maintaining the blood-brain barrier -These cells create the blood-brain barrier which isolates the CNS from the general circulation packed with microfilaments, provides a structural framework for the neurons of the brain and spinal cord. Repairing damaged neural tissue - in the CNS, damaged neural tissue seldom regains normal function. Astrocytes moving into the site of injury can make structural repairs that stabilize the tissue and prevent further injury. Guiding neuron development - astrocytes in the embryonic brain appear to be involved in directing both growth and interconnection of developing neurons

What effect does the influx of sodium ions have on a cell's charge?

At the normal resting potential the pump's primary significance is that it ejects sodium ions as quickly as they enter the cell

Dendrites

Extend out from the cell body Dendritic spine- In the CNS a neuron receives information from other neurons primarily at the dendritic spines

Discuss how drugs can interfere with key steps in synaptic activity

Interfere with neurotransmitter synthesis it can alter the rate of neurotransmitter release, prevent neurotransmitter inactivation or, prevent neurotransmitters from binding to receptors

Oligodendrocytes

The processes of oligodendrocytes generally are in contact with the exposed surfaces of neurons. Many axons in the CNS are sheathed. The membranous wrapping of insulation is called myelin. Myelin increases the speed at which an action potential travels along the axon. Many oligogendrocytes cooperate in the formation of a myelin sheath along the length of an axon. The axon is then said to be myelinated. The relatively large areas of the axon that are wrapped in myelin are called internodes. Small gaps of a few micrometers separate adjacent internodes. These gaps are called nodes or nodes of Ranvier (Rahn-ve-A). Myelinated axons appear glossy white, primarily because of the lipids that are present. Regions dominated by myelinated axons constitute the white matter of the CNS. Some axons are unmyelinated and may not be covered by the processes of neuroglia. These areas have a dusky gray color and they constitute the gray matter of the CNS

Synaptic terminals/knob

The synapse is located at the end of each axonal end branch. Here the end branch forms a small button-like knob (sn). This knob is adjacent to a tiny cleft or synapse (s). When a nerve impulse reaches this knob, a drug called a neurotransmitter is released from vesicles into the synapse The neurotransmitter diffuses across the gap and binds to receptors on the membrane of the adjacent neuron or muscle cell. This will initiate an electrical change in the membrane of the adlacent neuron leading to a nerve impulse in that cell.l

Classify neurons based on their structure

• Anaxonic • Bipolar neurons • Unipolar • Multipolar neurons

Compare and contrast the sympathetic with parasympathetic division

• The sympathetic arises from the thoracic and lumbar regions of the spinal cord • The parasympathetic arises from the brain and sacral region of the spinal cord

Name the four neuroglial cells and describe each cell's' function

• ependymal cells- • Astrocytes • Microglias. • Oligodendrocytes