Anatomy final

resting membrane potential: the potential difference in a resting neuron

Define resting membrane potential and describe its electrochemical basis.

it depends on differences in ion concentration and permeability. It is generated by different concentrations of Na+, K+,Cl- and protein anions

how is the resting membrane potential generated?

Graded potentials can be depolarizing or hyperpolarizing. Action potentials always lead to depolarization of membrane and reversal of the membrane potential Both are short-lived.

Compare and contrast graded potentials and action potentials.

voltage: measure of potential energy generated by separated electrical charges current: the flow of electrical charge from one point to another resistance: the hindrance to charge flow provided by substances through which the current must pass ohms law tells us the relationship: -current is directly proportional to voltage. the greater the voltage, the greater the current -there is no net current flow between points that have the same potential -current is inversely related to resistance, the greater the resistance, the smaller the current

Describe the relationship among current, voltage, and resistance.

1. nuclei are clusters of cell bodies that lie in the Central nervous system and ganglia lie in the Peripheral nervous system. 2. nucleus are bundles of axons in the Central nervous system and tracts are bundles of axons in the Peripheral nervous system.

Differentiate between (1) a nerve and a ganglia, and (2) a nucleus and a tract.

1. a nerve is one or more bundles of nerve fibers(axons in the PNS and tracts are another name for a nerve, except this bundle of nerve fibers (axons) is only found in the CNS. 2. a nucleus is a cluster of neuron cell bodies found only in the CNS and a ganglion is a name for cluster of neuron cell bodies found only in the PNS.

Differentiate between (1) a nerve and a tract, (2) a nucleus and a ganglion.

the myelin sheath protects and electrically insulates fibers and it increases the transmission speed of nerve impulses PNS: formed by Schwann Cells CNS: formed by oligodendrocytes

Explain the importance of the myelin sheath and describe how it is formed in the central and peripheral nervous systems.

-central nervous system (CNS): consists of the brain and spinal cord; control center of the nervous system -peripheral nervous system (PNS): part of the nervous system outside the CNS, consists of nerves (broken down into the sensory division and the motor division)

Explain the structural and functional divisions of the nervous system.

-chemically gated channels: open when the appropriate chemical binds -voltage gated channels: open and close in response to changes in the membrane potential -mechanically gated channels: open in response to physical deformation of the receptor

Identify different types of membrane ion channels.

sensory input, integration, motor output

List the basic functions of the nervous system.

-astrocytes: support and brace the neurons and anchor them to their nutrient supply lines. -microglial cells: touch nearby neurons, monitoring their health, and when they sense that certain neurons are injured or in other trouble, the microglial cells migrate toward them -ependymal cells: the beating of their cilia helps to circulate the cerebrospinal fluid that cushions the brain and spinal cord -oligodendrocytes: line up along the thicker nerve fibers in the CNS and wrap their processes tightly around the fibers. producing an insulating covering called a myelin sheath

List the types of neuroglia and cite their functions.

-first-class lever: the effort is applied at one end and the load is at the other, with the fulcrum somewhere between. -second-class lever: the effort is applied at one end of the lever and the fulcrum is located at the other, with the load between them -third-class lever: the effort is applied between the load and the fulcrum

Name the three types of lever systems and indicate the arrangement of effort, fulcrum, and load in each. Also note the advantages of each type of lever system.

Nodes of Ranvier

The ________ are gaps in the myelin sheath that occur at regular interval.

-structure: multipolar neurons (three or more processes), bipolar neurons (two processes), and unipolar neurons (single short process) -function: sensory neurons (transmit impulses toward or into the CNS), motor neurons (transmit impulses away from the CNS), and interneurons (lie between motor and sensory neurons shuttling signals through CNS pathways)

classify neurons by structure and by function.

Depolarization

decrease in membrane potential; inside of the membrane becomes less negative than resting membrane potential

absolute: period following stimulation during which no additional action potential can be evoked refractory: follows the absolute refractory period; interval when a threshold for action potential stimulation is markedly elevated

define absolute and relative frequency periods.

lever: a rigid bar that moves on a fixed point (fulcrum) when a force (effort) is applied to it -mechanical advantage: the large load is moved only a small distance but the effort required is also small -mechanical disadvantage: requiring a large effort to move a small load

define lever, and explain how a lever operating at a mechanical advantage differs from one operating at a mechanical disadvantage.

neuron: structural units of the nervous system Body- part of receptive region; major biosynthetic canter of neuron Axon- slender process extending from neuron; conducting region; generates nerve impulses and transmits them Dendrites- main receptive or input regions

define neuron, describe its important structural components, and relate each to a functional role.

saltatory conduction: current moves rapidly from myelin sheath gap to myelin sheath gap, propagating action potentials at each gap in saltatory conduction, the nerve impulse will jump between the spaces between the nodes of Ranvier (the pieces of insulation that surround the neuron). This is faster than continuous conduction, where the nerve impulse travels down the whole unmyelinated neuron.

define saltatory conduction and explain how it differs from continuous conduction.

-graded potentials: short-lived, localized changes in membrane potential, usually in dendrites or the cell body. -receptor potential: produced when a sensory receptor is excite by its stimulus -postsynaptic potential: produced when the stimulus is a neurotransmitter released by another neuron.

describe graded potentials and name several examples.

prime movers: major responsibility for producing a specific movement antagonists: oppose or reverse a specific movement synergists: help prime movers by adding a little extra force to the same movement or by reducing undesirable or unnecessary movements

describe the functions of prime movers, antagonists, and synergists.

When a muscle crosses two or more joints, its contraction causes movement of all of the spanned joints unless other muscles act to stabilize those joints. Example: the finger flexor muscles cross both the wrist and the finger joints, but you can make a fist without bending your wrist because synergistic muscles stabilize the wrist.

explain how a muscles position relative to a joint affects its action.

generated: resting state (all voltage-gated Na+ and K+ channels are closed), depolarization (voltage-gated Na+ channels open), repolarization (Na+ channels are inactivating and voltage-gated K+ channels open), hyperpolarization (some K+ channels remain open, and Na+ channels reset) propagation: Action potential is generated by the influx of Na+ through a given area of the membrane, which then establishes local currents that depolarize adjacent membrane areas in the forward direction which open voltage-gated channels and triggers an AP there

explain how action potentials are generated and propagated along neurons.

Hyperpolarization

increase in membrane potential; inside of the membrane becomes more negative than resting membrane potential

1. muscle location (example: temporalis overlies temporal bone) 2. muscle shape (example: deltoid muscle is triangular; deltoid = triangle) 3. muscle size (example: gluteus maximus and gluteus minimus are large and small gluteus muscles) 4. direction of muscle fibers (example: the rectus femoris is a straight muscle of the thigh) 5. number of origins (example: the biceps brachii muscle of the arm has 2 origins) 6. location of the attachments (example: the sternocleidomastoid muscle of the neck has a dual origin on the sternum and the origin on the sternum and clavicle, and it inserts on the mastoid process of the temporal bone) 7. muscle action (example: the adductor longus brings about thigh adduction)

list the criteria used in naming muscles. provide an example to illustrate he use of each criterion.

-circular: muscle fascicles are arranged in concentric rings -convergent: muscle has a broad origin;fascicles converge toward a single tendon of insertion -parallel: length of the fascicles runs parallel to the long axis of the muscle -pennate: fascicles are short and they attach obliquely to a central tendon that runs the length of the muscle

name the common patterns of muscle fascicle arrangement and relate them to power generation.

higher

typically, the higher the potential difference between two points, the ________ the voltage.

-70mv

what is the threshold for the resting membrane potential?