A&P II Exam 1

Sensory Functions of the Nervous System

Sense changes through sensory receptors

Motor function of the nervous system

To respond to stimuli by initiation action (motor neurons serve this function)

Integrative function of the Nervous System

Analyze incoming sensory information, store some aspects, and make decisions regarding appropriate behaviors

The Central Nervous system is made up of

The brain and spinal cord

The peripheral nervous system is made up of

Nervous tissue outside of the CNS (nerves and sensory receptors)

Sensory (afferent) division

Carries signals to your brain to help you touch, taste, smell and see

Motor (efferent)

Carries nerve impulses from the central nervous system to muscles and glands throughout the body

Somatic Nervous System

Conveys motor output from the CNS to skeletal muscles (voluntary)

Autonomic Nervous System

Conveys motor output from the CNS smooth muscle, cardiac muscle, and glands

The Autonomic Nervous system can be divided into the

sympathetic nervous system, parasympathetic nervous system, and enteric nervous system.

Neurons are made up of

A cell body (soma), dendrites, and axon

Dendrites

A short branched extension of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body

Axon

The long threadlike part of a nerve cell along which impulses are conducted from the cell body to other cells

Synapse

A junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter

Synaptic end bulb

The bulb at the end of the axon in which neurotransmitter molecules are stored and released

Synaptic vesicles

Store various neurotransmitters that are released at the synapse

Neurotransmitter

Chemical messengers that carry chemical signals from one neuron to the next target cell

Multipolar Neuron

Consists of one axon extending from the cell body and multiple dendrites grow out of it, making transmitting information easier

Bipolar Neuron

A type of neuron that has two extensions (one axon and one dendrite) leading from the cell body

Unipolar Neuron

Contains one axon extending from the cell body that extends into dendrites (not found in vertebrates)

Neuroglia

Any of the cells that hold nerve cells in place and help them work the way they should

Astrocyte

A large star-shaped cell that holds nerve cells in place and helps them develop and work the way the should

Fibrous Astrocytes

Cytoplasmic processes are long, few, smooth, thin and less branched

Protoplasmic astrocytes

Cytoplasmic processes are short, numerous, more branch and thick

Oligodendrocytes

The myelinating cells of the central nervous system

Microglial

The most prominent immune cells of the central nervous system and are the first to respond when something goes wrong in the brain

Ependymal Cells

A cell that forms the lining of the fluid-filled spaces in the brain and spinal cord

Schwann Cells

The major glial cell type in the peripheral nervous system; they play essential roles in the development, maintenance, function, and regeneration of peripheral nerves

Satellite Cells

Surrounds some neurons in the peripheral nervous stem; they provide nutrient support and protection

The myelin sheath is produced by

Schwann cells (PNS) and Oligodendrocytes (CNS)

White Matter

Composed primarily of myelinated axons

Gray Matter

The nervous system contains neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, and neuroglia

Action Potential

The change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell (allows communication over short and long distances)

Graded Potential

Proportional in amplitude to the size of the input stimulus (allows communication over short distances only)

Resting Potential

The electrical potential of a neuron or other excitable cell relative to its surroundings when not stimulates or involved in passage of an impulse

Resting membrane potential is determined by

1. Unequal distribution of ions in the ECF and cytosol

2. Inability of most cytosolic anions to leave the cell

3. Electrogenic nature of the Na+/K+ ATPases

Electrical signals produced by neurons and muscle fibers rely on

1. Leak channels

2. Ligand-Gated channels

3. Mechanical-Gated channels

4. Voltage-Gated channels

Leakage Channels

Alternate between open and closed

K+/Na+ Channels

Membrane proteins that allow rapid and selective flow of K+/Na+ ions across the cell membrane

Ligand-Gated Channels

Respond to chemical stimuli (ligand binds to receptor)

Mechanically-Gated Channels

Respond to mechanical vibration or pressure stimuli

Voltage-Gated Channels

Respond to direct changes in membrane potential

Electrical Synapse

Gap junctions connect cells (connexons) and allow the transfer of information to synchronize the activity of a group of cells

Chemical Synapse

One-way transfer of information from a presynaptic neuron to a postsynaptic neuron

Excitatory Postsynaptic Potentials

A depolarizing postsynaptic potential; Contains cation channels

Inhibitory postsynaptic potentials

A hyperpolarizing postsynaptic potential; Contain chloride channels

Acetylcholine

Slows heart rate

Biogenic Amines

NE: arousal, dreaming, mood

DA: emotional, addictive, pleasure

ATP and other purines

Excitatory CNS and PNS

Nitric Oxide

NO, NOS, memory, learning

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Carbon Monoxide

Excitatory, memory, dilation, vision, olfaction

Neural Circuits

A functional group of neurons that process specific types of information

Plasticity

The capability to change based on experience

Regenerate

The capability to replicate or repair

The Spinal Cord is protected by

Bone (vertebrae), Connective Tissue (meninges), Fluid (cerebrospinal fluid)

The meninges are composed of three layers

Dura mater, Arachnoid mater (subarachnoid space CSF), Pia mater

Dura Mater

The tough outermost membrane enveloping the brain and spinal cord

Arachnoid Mater

A fine, delicate membrane, the middle one of the three membranes or meninges that surround the brain and spinal cord, situated between the dura mater and the pia mater

Pia Mater

A delicate innermost membrane enveloping the brain and spinal cord

Cervical Nerves

8 Pairs

Thoracic Nerves

12 Pairs

Lumbar Nerves

5 pairs

Sacral nerves

5 Pairs

Coccygeal nerves

1 Pair

Branches

Rami

Plexuses

A network of axons

Intercostal Nerves

Aids in the contraction of muscles and the return of sensory information from the skin and parietal pleura

Dermatomes

Certain segments of the skin are supplied by spinal nerves that carry somatic sensory nerve impulses to the brain

Cervical Plexus

C1-C4 (C5)

Brachial Plexus

C5-C8+T1

Lumbar Plexus

L1-L4

Sacral Plexus

L4-L5+S1-S4

Coccygeal Plexus

S4-S5

Cervical Plexus

Supplies the skin and muscles of the head, neck, superior portion of the shoulders and chest, and diaphragm

Brachial Plexus

Provides almost the entire nerve supply to the shoulders and upper limbs

Long Thoracic

C5-C7 Serratus anterior muscle

Musculocutaneous

C5-C7 coracobrachialis, biceps brachii, brachialis muscles

Thoracodorsal

C6-C8 latissimus dorsi muscle

Axillary

Deltoid, teres minor, skin

Median

C5-T1 Flexors of forearm, lateral palm, skin of lateral 2/3 palm, fingers

Radial

C5-T1 triceps brachii, extensor muscles, skin of forearm, lateral 2/3 dorsum hand, fingers

Medial pectoral

C8-T1 pectoralis major/minor

Medial cutaneous nerve of forearm

C8-T1 skin of medial and posterior aspects of forearm

Ulnar

C8-T1 flexors carpi ulnaris, most muscles of hand, skin of medial side of hand, little finger, medial half of ring finger

Lumbar Plexus

Vital for the functioning of the lower extremity and maintaining the ability to extend the knee, flex the hip, and adduct the thigh

Sacral Plexus

A nerve plexus that provides motor and sensory nerves for the posterior thigh, most of the lower leg, the entire foot, and part of the pelvis

Inferior Gluteal

L5-S2 Gluteus maximus

Nerve to Piriformis

S1-S2 piriformis muscle

Nerve to quadratus femoris

Quadratus femoris and inferior gemellus muscles

Sciatic

L4-S3 tibial and common fibular (at knee), hamstring and adductor magnus

Tibial

L4-S3 gastrocnemium, soleus, tibialis posterior, flexor digitorum longus

Superficial fibular

L4-S2 fibularis longus and brevis, skin of leg and foot

Deep fibular

Tibialis anterior, extensor halluces longus, adjacent sides of great and second toes

Spinothalamic Tract

Pain, temperature, itching, tickling, deep pressure, crude touch

Posterior column

Gracile/cuneate fasciculus→light pressure, vibration, discriminative touch, conscious proprioception

Direct Pathways

Lateral corticospinal, anterior corticospinal, cortiocobulbar tracts→voluntary movements

Indirect Pathways

Rubrospinal, tectospinal, vestibulospinal, lateral reticlospinal, medial reticulospinal→automatic movements

Ipsilateral

Belonging to or occurring on the same side of the body

Contralateral

Relating to the side of the body opposite to that on which a particular structure or condition occurs

Monosynaptic

Involving a single synapse (two neurons, one synapse)