Intro to nervous system

Question 1

What are the functions of the nervous system?

Answer 1

Sensory input, integration, motor output

Question 2

Sensory input

Answer 2

monitoring stimuli occuring inside and outside the body

Question 3

Integration

Answer 3

Processing of sensory input and formulation of motor commands

Question 4

Motor output

Answer 4

Response to stimuli by activating effector organs

Question 5

What does the nervous system consist of?

Answer 5

Central nervous system (brain and spinal cord) and peripheral nervous system ( all nervous tissue outside the CNS)

Question 6

Reflex

Answer 6

Predictive rapid response to a stimulus

• Receptor detects stimulus
• afferent/sensory neuron relays info to the CNS *control/integration center (region of the CNS that processes sensory info and sends motor commands)
• Efferent/motor neuron carries motor commands away from CNS to the effector
• effector (muscle or gland that responds to motor commands by producing the response)

Question 7

Afferent/ sensory division of PNS

Answer 7

Carry info from receptors to the CNS

Question 8

Somatic afferent fibers

Answer 8

Carry impulses from skin, skeletal muscles and joints

Question 9

Visceral afferent fibers

Answer 9

Carry impulses from organs within ventral body cavities

Question 10

Special sensory afferent fibers

Answer 10

Carry impulses from nose, eye, tongue, and ear

Question 11

Efferent/motor division of PNS

Answer 11

Motor neurons carry commands away from CNS to effectors

Question 12

Somatic efferent fibers

Answer 12

control voluntary skeletal muscle contraction

Question 13

Autonomic efferent fibers

Answer 13

Control involuntary cardiac muscle, smooth muscle and glands

Question 14

Sympathetic division

Answer 14

travels through thoracic and lumbar spinal nerves and produces the fight or flight responses to mobilize energy reserves and prepare for activity to deal with stress

Question 15

Parasympathetic division

Answer 15

Travels through cranial nerves and sacral spinal nerve and produces the rest and digest maintenance responses to store and conserve energy

Question 16

Structure of a typical neuron

Answer 16

• Soma-cell body, contains nucleus and organelles
• Dendrites-branching extensions that contain receptors to detect neurotransmitters from other neurons
• Axon hillock- where cell body tapers into the axon, site where the action potential originates
• Axon-single long process, transmits action potential away from soma
• Axolemma-Plasma membrane of an axon
• Myelin sheath-Insulation formed by glial cells wrapping around the axon, nodes of ranvier-gaps in myelin sheath, internodes-segements of myelin
• Axon terminals-enlarged distal ends of an axon that contain secretory vesicles filled with neurotransmitters (synaptic vesicles)

Question 17

Interneurons (association neurons)

Answer 17

create neural circuits enabling communication between sensory or motor neurons and the CNS, only found in CNS

Question 18

Multipolar neuron

Answer 18

multiple processes branching off the cell body, numerous dendrites and one axon

Question 19

Pseudounipolar neuron

Answer 19

appear to have one extension off the cell body. This extension branches forming a long axon with dendrites on one end and axon terminals on the opposite end *most sensory neurons of the PNS

Question 20

Bipolar neuron

Answer 20

Two extensions from cell body, one dendrite and one axon *Found in special sense organs

Question 21

Neuroglia (glia)

Answer 21

cells that surround and support neurons

Question 22

Astrocyte (CNS)

Answer 22

Star shaped, processes cling to neurons and capillaries

• Provide structural support-anchor neurons to surrounding tissues and capillaries
• Maintain blood brain barrier-feet wrap around capillaries and controls uptake of selected materials from the blood
• Adjusts interstitial environment-recaptures released neurotransmitters and leaked ions
• Guides neuron development-directs growth of neurons and synapse formation

Question 23

Oligodendrocyte (CNS)

Answer 23

Wrap cytoplasmic processes around the axons of neurons

*Forms a white fatty insulation material called a myelin sheath

Question 24

Microglial cells (CNS)

Answer 24

Oval cells with long thorny processes

*Remove cellular debris and pathogens

Question 25

Ependymal cells (CNS)

Answer 25

Ciliated cells, line chambers filled with CSF * Monitor and maintain the composition of CSF * Assist in circulation of CSF

Question 26

Schwann cells (PNS)

Answer 26

Surrounds and protects axons in PNS * Forms myelin sheath around some axons of PNS * Neurilemma-outer layer that contains schwann cell cytoplasm

Question 27

Satellite cells (PNS)

Answer 27

Surround cell bodies of neurons | *Isolates cell body and regulates exchange of nutrients and waste

Question 28

Membrane potential

Answer 28

Separation of charge across the plasma membrane measured in volts

Question 29

Resting membrane potential

Answer 29

Membrane potential at rest when the cell is not receiving information in the form of a graded potential of sending out information as an action potential. Resting potential is typically around -70mV *Chemical gradients-higher Na+ outside cell, higher k+ inside cell

Question 30

Depolarization

Answer 30

The membrane potential becomes less negative | *When neurons are stimulated Na+ channels open and Na+ rushes into the cell

Question 31

Graded potential

Answer 31

A localized change in membrane potential that is short lived and dissipates as it travels * Can be stimulated by neurotransmitters binding to ligand gated channels, mechanical stress, or temperature change * If the stimulus is excitatory it will cause depolarization of the membrane

Question 32

Action potential

Answer 32

Electrical impulse producing a brief reversal of the membrane potential that travels down the entire length of the axon from the axon hillock to the axon terminals

Question 33

Rising (depolarization) phase of the action potential

Answer 33

Na+ rushes in through voltage gated Na+ channels

Question 34

Threshold potential

Answer 34

V-gated Na+ channels open at membrane potential of -55mV

Question 35

Falling (Repolarization) phase of action potential

Answer 35

K+ rushes out through voltage gated K+ channels

Question 36

Synapse

Answer 36

Junction between two neurons or a neuron and muscles, glands, or cells

Question 37

Structure of a synapse

Answer 37

* Presynaptic neuron-transmits impulse towards synapse, axon terminals of the presynaptic neuron release neurotransmitters * Synaptic cleft-fluid filled space where neurotransmitters are released * Postsynaptic cell (Neuron, muscle, gland, etc)-receives information from the presynaptic neurons