Nervous system EXAM 3

Neuron structural components and relate to each role

-large highly specialized cells that conduct impulses, extreme longevity (100+ yrs) -Amitotic- w/ few exceptions -Highly metabolic rate; requires continuous supply of oxygen and glucose -ALL have CELL BODY and one or more processes

function of astrocytes

(CRIES + G) Cling to neurons, synaptic endings & capillaries -Control chemical environment around neurons -Respond to nerve impulses & neurotransmitters -Influencer neuronal functioning ( participate in information processing in brain -Play role in EXCHANGES between capillaries and neurons - support and brace neurons - Guide migration of young neurons

The_________nervous system provides involuntary regulation of smooth muscle, cardiac muscle, and glandular activity.

Autonomic

Define resting membrane potential and describe its electrochemical basis

Potential difference across membrane of resting cell; approximately-70 mV in neurons (cytoplasmic side of membrane negatively charged relative to outside) -POLARIZED GENERATED BY..... - differences in ionic makeup of ICF and ECF - differential permeability of the plasma membrane

Describe action potential

Principal way neurons send signals, principal means of long lasting neural communication Occur ONLY IN muscle cells and axons of neurons Do not decay over distance as graded potential do Brief reversal of membrane potential with a change in voltage of ~100 mV

function of oligodendrocytes

Processes wrap CNS nerve fibers, forming insulating myelin sheaths in thicker nerve fibers

Cranial nerves II, the optic nerve sends nerve impulses to the brain carrying information about the things we see. These nerve fibers most likely belong to which division of the nervous system?

Sensory (afferent) division

Which of the following is an excitatory neurotransmitter secreted by motor neurons innervating skeletal muscle?

acetylcholine

Describe the Importance and forming of myelin sheath

- Composed of whitish protein substance (myelin) and segmented sheath around most long or large diameter axons -protects and electrically insulated axon, increases speed of nerve impulse transmission

Which of the following statements about the action potential is false?

A. During the repolarization phase, sodium channels close and potassium channels open B. Repolarization occurs as potassium ions leave the axon C. The rapid depolarization phase is caused by the entry of potassium ions D. During the hyperpolarization phase, the ion pumps re-establish the sodium and potassium concentrations across the cell membrane C

Which of the following is not a characteristic of neurons?

A. They conduct impulses B. They are mitotic C. They have extreme longevity D. They have an exceptionally high metabolic rate B

Which of the following is not true of graded potentials?

A. They increase amplitudes as they move away from the stimulus point B. They are the cause of fused tetany C. They can form on receptor endings D. They are short-lived A

Explain how action potentials are generated and propagated down a neuron

All gated Na+ & K+ channels are closed Only in leakage channels for Na+ & K+ are open - this maintains the resting membrane potential

Define neuron

Nerve cells, structural units of nervous system

function of ependymal cells

Form permeable barrier between cerebrospinal fluid (CSF) in cavities and tissue fluid bathing CNS cells

Functional classification of neurons

Grouped by direction in which nerve impulse travels relative to CNS Three types Sensory (afferent) Motor (efferent) Interneurons

function of microglial cells

Has thorny processes that touch and monitor neurons, migrate toward injured neurons, and can transform to phagocytize microorganisms and neuronal debris

List the basic functions of the nervous system and explain them

Sensory input= information gathered by sensory receptors about internal and external changes Integration = processing and interpretation and sensory inputs Motor output = activation and effector organs (muscle & glands) produces a response

Describe graded potentials.

Short-lived, localized changes in membrane potential Either depolarizations or hyperpolarizations Cause local current (flow) Decay rapidly with distance due to ion flow across the membrane through leakage channels

List the types of neuroglia

astrocytes, oligodendrocytes, ependymal cells, microglia

When a neurotransmitter like GABA is acting in an inhibitory manner which of the following is likely a result of the GABA acting on the post synaptic cell?

hyperpolarization of the postsynaptic cell membrane

Which of the choices below describes the ANS?

motor fibers that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands

Saltatory conduction is made possible by ________.

myelin sheath

The interior surface of a neuron's plasma membrane at resting membrane potential will have a ________.

negative charge and contains less sodium than outside of the cell