Exam 2

Question 1

Nervous System

Answer 1

neurotransmitters produced by neurons
Travel short distances across synapses
allows system to react quickly

Question 2

Endocrine System

Answer 2

Uses chemicals to carry messages
hormones secreted directly into bloodstream
Travel long distances to reach targets
body reacts more slowly to changes

Question 3

What are the basic functions of the nervous system

Answer 3

Sensory functions, integrading functions and motor functions

Question 4

Sensory functions of the nervous system

Answer 4

The nervous system sense the changes from within the body or out side of the body and conveys this information to the spinal cord and brain. In the brain and spinal cord, the sensory information is recived, analyzed, stored

Question 5

Intergrading functions in the nervous system

Answer 5

integrated to produce a response and integrated to produce a response.

Question 6

Motor functions in the nervous system

Answer 6

The response may be to command muscles to move or produce glandular secretions

Question 7

Nervous Systems 2 divisions

Answer 7

Central Nervous System(CNS) and Peripheral Nervous System(PNS)

Question 8

Central Nervous System consist of

Answer 8

Brain and spinal cord

Question 9

Peripheral Nervous System consist of

Answer 9

nerves to link the CNS to the rest of the body

Question 10

Neurons = Nerve Cells are

Answer 10

Basic, functional unit of the nervous system
Have high requirement for oxygen
cannot reproduce but can regenerate cell processes
have support and protection from neuroglia cells

Question 11

What is the function of neuroglial (glial) cells?

Answer 11

Support and protection of the nervous system
They out number the neurons 10 to 1, but they are not directly involved in the transmission of information or impulses through the nervous system. They are important and necessary for the neurons to do their job.

Question 12

Name the three parts of a neuron

Answer 12

Axon, cell body(cyton, perikaryon, soma), dendrites

Question 13

Which of the two nerve processes (extensions) is the longest?

Answer 13

Axon is the longest

Question 14

Which process receives stimuli?

Answer 14

dendrites receive stimuli

Question 15

Which part contains cellular organelles?

Answer 15

cell body has organelles

Question 16

Dendrite Cell Processes

Answer 16

short, numerous, multibranched
Receive stimuli from other neurons
Conduct stimuli toward cell body (afferent)
may serve as sensory receptors
heat, cold, touch, pressure, stretch, etc.

Question 17

Axon Cell Processes

Answer 17

single, long process
may be covered with myelin
white matter
Conducts nerve impulses away from cell(efferent) toward another neuron of effector cell

Question 18

. What is myelin? What purpose does it serve in regard to nerve cell function?

Answer 18

White covering over axon that increases speed of conduction od impulse along the axon.

Question 19

What is the difference between white and grey matter?

Answer 19

White matter are the processes (axon, dendrites)
Grey matter is the cell bodies

Question 20

What are afferent nerves? What is another name for them?

Answer 20

Conducts impulses from the periphery towards the CNS
Also called sensory

Question 21

What are efferent nerves? What else are they called?

Answer 21

Conduct impulses from the CNS toward periphery
Also called motor.

Question 22

Autonomic NS

Answer 22

involuntary to smooth muscle, cardiac muscle, endocrine glands

Question 23

Somatic NS

Answer 23

Voluntary; impulses to skeletal muscle

Question 24

Describe the relative concentrations of sodium and potassium ions in a resting nerve cell. What specialized molecule maintains this concentration?

Answer 24

Resting nerve cell has higher concentration of sodium outside cell, potassium inside. Specialized molecules located on neuron’s cell membrane called sodium-potassium pump, It pump sodium ions from inside the cell to the outside, and pump potassium from outside the cell to inside the cell. requires energy

Question 25

What is meant by polarization of the neuronal membrane?

Answer 25

Polarization refers to position charge on outside of membrane, and negative charge inside. Creating this electrical charge which generations the nerve impulses

Question 26

Explain the difference in electrical charges across the membrane in a resting nerve cell.

Answer 26

Resting cell has a positive outside and a negative inside

Question 27

How does the nerve cell membrane maintain this charge?

Answer 27

Maintained by sodium- potassium pump. A resting cell maintaining the negative charge means that its always charged up ready to create an impulse (charge batteries ready to go)

Question 28

What type of impulses can stimulate a nerve cell?

Answer 28

Impulses can be external (heat, touch, taste) Internal (pressure, stretch, hormone) Can be electrical, chemical, or physical

Question 29

What changes in the sodium concentration occur here an impulse stimulates a neuron?

Answer 29

When an impulse stimulates a nerve, a specialized molecule on the cell membrane called a sodium channel opens. This allows only sodium to pass through. Because a higher concentration of sodium exists outside the cell, sodium flows inside by passive diffusion.

Question 30

What effect does this have on the electrical charge on the nerve cell membrane?

Answer 30

sodium (positive ion) is attracted into cell by net negative charge inside.

Question 31

depolarization

Answer 31

When an impulse stimulates a nerve, a specialized molecule on the cell membrane called a sodium channel opens. This allows only sodium to pass through. Because a higher concentration of sodium exists outside the cell, sodium flows inside by passive diffusion. Also, sodium (positive ion) is attracted into cell by net negative charge inside.

Question 32

Explain what is meant by depolarization. What is an action potential?

Answer 32

Loss of polarization on membrane when positively charges sodium rushes in. Large change in electrical charge from negative to positive is called the action potential and signals the depolarization of the neuron

Question 33

What happens to potassium concentration during repolarization? What effect does this have on the electrical charge on the nerve cell membrane?

Answer 33

Following depolarization, the sodium channels close and potassium channels open, allowing potassium to pass through. Potassium diffuses outside cell due to diffusion, also due to positive charge inside cell created by influx of sodium (like charges repel). Because potassium ions are positive, when they flow outside, causes the inside to become negative. This change of the cells charge back towards negative resting membrane potential is called repolarization. Sodium and Potassium now on opposite sides of membrane , again

Question 34

What happens following repolarization to restore the sodium and potassium levels to their original resting state?

Answer 34

Repolarization results in proper resting membrane charge, but sodium and potassium are on opposite sides of membrane from where they started in the resting cell. To restore the sodium and potassium to their original locations on either side of the membrane, the sodium- potassium pump quickly moves the sodium and potassium back to their original sides.

Question 35

What characteristics of a stimulus determines whether or not depolarization will occur?

Answer 35

The stimulus must be strong enough to cause depolarization it must be above threshold

Question 36

What is meant by wave of depolarization or conduction of the action potential?

Answer 36

If a stimulus is above threshold, sodium channels would open at the site of the stimulus, as well as adjacent sites to the initial stimulus. This would allow sufficient sodium influx into these adjacent areas to reach threshold, causes a spreading wave of sodium channels to open over the entire neuron. This wave of sodium channels opening to allow sodium influx is called the wave of depolarization.The influx of sodium ions during depolarization was called the action potential; therefore the wave of depolarization is called the conduction of the action potential. The influx of sodium ions during depolarization was called the action potential; therefore the wave of depolarization is called the conduction of the action potential.

Question 37

What is meant by wave of depolarization or conduction of the action potential purpose does this serve?

Answer 37

This serves to spread the impulses along the neron so it can be passed to another neuron, or a muscle or gland

Question 38

Explain the all- or- none principle as it relates to the stimulus and nerve impulse?

Answer 38

The all- or – nothing principle refers to the complete depolarization of the neuron, or none at all Regardless of how strong the initial impulse was, if it was above threshold, the action potential would be conducted along the entire neuron with uniform strength.

Question 39

Explain saltatory conduction in relation to the myelin sheath and nodes of Ranvier. What role does this play in nerve impulse conduction?

Answer 39

Saltatory conduction(skipping, jumping) is a rapid means of conductiong an action potential The myelin sheath has gaps along the neuron called nodes of Ranvier. The myelin insulates the axon and prevents sodium from flowing across the membrane. Depolarization occurs only at the nodes, jumping from one to the next, spreading the impulse faster