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Anatomy_Neuro_Lec7
Neurological Study Cards
| Question | Answer |
|---|---|
| The cerebellum | Subconscious activities associated with skeletal muscle contraction needed for smooth, coordinated movements for our daily living |
| The brain stem | (mid-brain, pons, and medulla) associated with autonomic behaviors that are necessary for survival (respiration and cardiac function) |
| Diencephalon | (thalamus, hypothalamus, sub-thalamus and epithalamus) sometimes considered part of the cerebrum or brain stem, encloses the 3rd ventricle |
| Cerebral Hemispheres | (ie. the cerebrum) 84% of brain mass; provides motor & sensory function; each hemisphere supplies function to the opposite side of the body. Encloses lateral ventricles |
| Ventral Rami | Supplies anterior-lateral skin of and muscles of the neck, trunk, and some of the head, and all of the muscles and skin of the extremities. Their distribution is complicated by plexus formation (except segmental thoracic ventral rami) |
| Dorsal Rami | Supplies the muscles and skin of the medial back, segmental distributed. They turn sharply posteriorly and divides into 2 branches - one deep (muscle) and one shallow (skin) |
| Lumbosacral Plexus | Ventral rami of T12-L4 (lumbar) and L4-S5 (Sacral), Supplies muscle and skin of lower limb and pelvic girdle |
| Brachial Plexus | Ventral rami of lower cervical nn. (C5-C8, T1). Supplies muscles and skin of upper limb & shoulder girdle |
| Cervical Plexus | Ventral Rami of upper cervical nn. (C1-C5) Supplies most of anterior & anterior muscles of the neck, some skin of the head and most of the neck skin, and skin of the upper portion of the shoulder and thorax |
| Nerve Branching | Nerve branches are a seperation of nerve bundles. When nerves join, the fibers do not unite but intermingle within the same epineurium |
| Epineurium | Wraps around the entire nerve and holds it loosely to the connective tissue through which it runs |
| Perineurium | Connective tissue and squamous epithelium; it surrounds each fasciculus (or bundle of nerve fibers) and branches inward |
| Endoneurium | Delicate layer of connective tissue around each nerve fiber; it is within the perineurium |
| Nerves | Bundles of nerve fibers that lie outside of the CNS (ie the PNS) |
| The Crossed Extensor Reflex | Involves the collateral branches of the sensory neurons innervating an excitatory inter-neuron to the alpha motor neuron to the skeletal muscles to the opposite limb/body part (usually an extensor). |
| Reciprocal Innervation | Involves the collateral interneuron going to the alpha motor neuron innervating the inhibitory interneuson going to the alpha motor neuron of the antagonists (usually extensors) |
| The withdrawal reflex | This reflex functions to remove a limb or body part from a painful stimulus. Involves w/ nociceptors. These interneurons directly synapse w. the alpha motor neurons which stimulate withdrawal from the stimulus. |
| Golgi tendon reflex | Prevents contracting muscles from applying too much tension to the tendons they are attached to |
| Muscle spindles | responsible for stretch reflexes, control posture, muscle tension and muscle length |
| Gamma Motor Neuron | regulate the sensitivity of the muscle spindles |
| The stretch reflex | simplest reflex is there because no interneuron. Muscles contract in response to a stretching force applied to them. Specialized skeletal muscle fiber |
| Reflex arcs | Most basic functional unit fo the nervous system. (1) sensory receptor (2)Sensory Neuron (3) Interneuron [not every case] (4) Motor Neuron (5)Effector Organ |
| Myelination in the CNS&PNS | Many nerves n the CNS acquire myelin; not all axons have it. Unmyelenated fibers are also surrounded by neuroglial cells for support. Neural Cell bodies and dendrites are never myelinated |
| Myelination in the PNS | Individual nerve fibers may or may not be myelinated but are surrounded by schwann cells and neurolemmal sheath (endoneurium) |
| Schwann Cells | Myelinate axons to increase functional performance of neurons. Schwann cells can surround an axon and not myelinate them |
| Satellite Cells | Help regulate nutrient and waste exchange, in PNS |
| microglia | Smallest of the meuroglia, phagocytic in nature |
| astrocytes | Most common neuroglea with a variety of functions. Control Interstitial movements within cytoplasm, maintain blood-brain barrier, Provides structural framework of CNS, Repairs damaged neural tissue |
| Ependymal Cells | Produce Cerebral Spinal Fluid |
| Oligodendrocytes | Myelinate axons to increase functional performance of neurons |
| Multipolar Neuron | Have several dendrites and single axon, that may or may not have multiple branches-- most common neuron |
| Pseudounipolar Neurons | A sngle axon w/ dendrites on either end, with the cell body situated off to one side. Typically sensory neurons of the PNS |
| Bipolar Neurons | A single cell body with 2 axons and their dendritic extensions -- rare, unmyelinated and found in special sense organs |
| Anaxonic Neurons | Small, only in the CNS, hard to distinguish dendrite from the axon |
| Trigger Zone | axon hillock and initial zone, where AP start down the axon |
| Axons | nerve fibers are thin and thread-like, arise from a cone shaped portion of the soma called the axon hillock. Just below the axon hillock, there is the initial segment. Different cytoplasm |
| Dendrites | Extensions of the cell body that recieve incoming synaptic information. Characterized by branching. Conduct impulses toward the cell body |
| Pia Mater | the innermost layer of the mater, thinnest |
| Arachnoid Mater | The second layer, seperated from the dura by a subdural space |
| Thecal sac | Dura forms a sac that surrounds the spinal cord-- attaches to teh foramen magnum to the 2nd sacral vertebra and its continuous w/ the same layer surrounding the brain |
| Epidural Space | Seperate the spinal cord from the dura mater. True space unlike around the brain |
| Dura Mater | Outermost meninges and thickest layer |
| Regeneration of axons/ fibers of nerve cells | Cells in the PNS do have the ability to regrow. In CNS, there is no endoneurium or schwann cells, and the prevalence of astrocytes inhbit axonal regrowth |
| Degeneration | Initially, swelling of the cell body (chromatolysis), within 3-5 days, all of teh axon distal to the injury will degenerate. Macrophage will come in and clean up |
| Efferent Neuron | Descending motor signals from other CNS centers -- exiting |
| Afferent Neuron | Primarily peripheral/sensory information- typically ascending |
| Post-synaptic cell | The cell that recieves the signal is a post-synaptic cell |
| Pre-synaptic cell | The cell that transmits the signal toward the synapse |
| Synapse | An area where one nerve fiber makes contact w/ another neuron or an end organ-- can be electrical or chemical |
| cell body | AKA Soma/Perikaryon-- the metabolic and genetic center of a neuron. small overall part of a neuron's structure. Lots of Endoplasmic Reticulum, mitochondria, and other neurofilaments |
| Neurons | Recieve stimuli and transmit action potentials to other neurons or effectors. basic unit of structure and function within the nervous system. Consists of (1) a cell body (2) processes called Dendrites and axons |
| Visceral Afferents | Sensory fibers that convey impulses from the visceral organs (organs within the ventral cavity) -- Involuntary NS. Divides into Sympathetic and Parasympathetic |
| Somatic Afferents | Sensory fibers that convey impulses from the skin, skeletal muscles and joints (voluntary NS) |
| Motor Division | Carries impulses away from the CNS to effector organs, the muscle and glands -Somatic and Visceral NS |
| Sensory Division | (Afferent) carries impulses to the CNS from sensory receptors located throughout the body |
| Spinal Ganglion | A collection of nerve cell bodies outside of the CNS, Mini brain or coordination center |
| Peripheral Nerve | A bundle of nerve fibers (axons) in the PNS, held together by a connective tissue sheath; referred to as either cranial nerves, (coming from the brain) or spinal nerves (coming from the spine) |
| Peripheral Nervous System | Consists of nerve fibers and cell bodies outside the CNS that conducts impulses to or away from the CNS |
| Tract | A bundle of Nerve fibers (axons) connecting neighboring or distant nuclei of the CNS |
| Nucleus | A collection of nerve cell bodies in the CNS |
| Saltatory Conduction | Myelinated axons utilize this --a local current at a node of Ranvier depolarizes that membrane and creates a current that flows through the lipid membrane (myelin towards the next node |
| Central Nervous System | The CNS consists of the bran and the spinal cord, Primary function is integrating and coordinating incoming and outgoing neural signals; and carrying out higher mental functions like thinking and learning |
| Continuous conduction | Unmyelinated axons utilize this. Local current causing a depolarization of the membrane and its adjacent membrane from origination to end point |
| Lateral Column | White matter, located away from the midline of the spinal cord |
| Ventral Column | White Matter, is in the anterior location |
| Dorsal Column | of the white matter, is in the posterior position of the spinal cord |
| Lateral horn Cells | (exist only in some part of the cord) give rise to pre-ganglionic fibers of autonomic nervous system |
| Anterior or ventral Horn Cells | Give Rise to voluntary motor fibers, gray matter. |
| Posterior or Dorsal Horn Cells | Gray matter, of card receive incoming sensory fibers |
| Gray Matter | Comprised of cell bodies, dendrites and unmyelinated axons. Spinal Cord--> Central Brain--> Interal |
| White Matter | Comprised of myelinated axons, grouped together to form tracts peripherally located in teh spinal cord. internally in the brain |
| Filum Terminale | anchors the conus medullaris to the coccyx |
| Denticulate ligaments | Within the pia mater form a strong adhesion of the dura and the pia and nervous tissue that makes up the spinal cord |
| Subarachnoid space | Seperates the pia and arachnoid mater and is where blood vessels and cerebral spinal fluid is found |
| afterpotential | Period of hyperpolarization following each Ap, occurs because the K+ channels remain open for a short time, allowing the membrane potential to return to its initial state |
| Repolarization | As maximum levels fo NA+ enter and K+ exit the membrane the change in the membrane potential causes the NA+ channels to begin closing. K+ cahnnels continue to open. K+ movement continues but Na+ stops |
| Depolatization | Increase in the opening of na+ channels along the plasma membrane. Once threshold reached, Na+ diffused into the cells, utilizing a positive feedback loop. Plasma membrane becomes net positive |
| All-or-none principal | Action potentials occur due to this principal, a stimulus must be large enough to satisfy the positive feedback loop system. Hits the threshold |
| benefits of myelination | increases conductance and speed of action potentials, uses less energy since the Na+/k+ pump has less work to do, and needs less ATp to reset the membrane to its resting state |
| Nodes of Ranvier | Constrictions separating successive segments of myelin are called nodes of ranvier. relatively small charges at the nodes are needed to depolarize since there are increased NA+ channels. Typically you see one schwann cells to each internodal segment |
| Schwann Cells | groups of unmyelinated fibers can be surrounded by a schwann cell, Cells can surround and add to the myelination of one cell |
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