Quiz 1 (suzanne's)

Question 1

Two major classes of cells:

Answer 1

Neurons: carry/ transmit information by the conduction of electrical impulses / action potentials.

Glia or neuroglia (“glue”) cells: provide support and maintenance functions for neural tissue.
Remember: Glia cells are unable to transmit potentials.

Question 3

Glia or neuroglia (“glue”) cells

Answer 3

provide support and maintenance functions for neural tissue.

Remember: Glia cells are unable to transmit potentials.

Question 4

Neurons: 3 types

Answer 4

Motor/ Efferent (descending): they are coming out from the CNS and PNS to the effector organs and tissues. They “make things happen”.

Sensory/ Afferent (ascending). They bring information from the effector organs and tissues to the PNS/ CNS for interpretation.

Associative / interneurons: compile a “balance sheet”. You can consider them “middle men”. They are majority of neurons. Integrate sensory information elicit motor response.

Question 5

Efferent

Answer 5

Motor neurons
Descending

they are coming out from the CNS and PNS to the effector organs and tissues. They “make things happen”.

Question 6

Afferent

Answer 6

Sensory neuron
Ascending

They bring information from the effector organs and tissues to the PNS /CNS for interpretation.

Question 7

Associative

Answer 7

Interneurons

compile a “balance sheet”. You can consider them “middle men”.They are majority of neurons.

Question 8

Central Nervous System (CNS)

Answer 8

Interneurons

compile a “balance sheet”. You can consider them “middle men”.They are majority of neurons.

Question 9

Glia cells: 6 types

Answer 9

1. Schwann cells: insulating (organized into myelin), and assist regeneration/ repair of axons within PNS.
2. Oligodendrocytes: insulating and resist regeneration within CNS.
3. Astrocytes (CNS): form blood-brain barrier
4. Microglia (CNS): a “sanitation department” macrophages of brain and spinal cord, clear cellular debris and dead neurons through phagocytosis, first line of immune defense for cns.
5. Satellite cells (PNS): provide support within ganglia (clusters of functionally united neurons)
6. Ependymal cells (CNS): Secrete CSF within brain ventricles; provide brain-CSF barrier.

Question 10

Somatic Nervous System:

Answer 10

controls and innervates-

The external lining and internal lining (peritoneum) of the body wall : sensory and motor

Extremities: sensory and motor

Special senses: smell, taste, vision, hearing, equilibrium

NOTE: There are two exceptions on the body wall and extremities:

• Erector pili muscles (“goose bumps”) they are smooth muscles
• Sweat glands
• Both are controlled by ANS

Question 11

Peripheral Nervous System (PNS)

Answer 11

Somatic Nervous System (SNS)
Autonomic Nervous System (ANS)
Enteric Nervous System (ENS)

clusters of related neurons (cell bodies or soma) are called:
GANGLIA (GANGLION)
bundles of related axons: NERVE(S).

Question 12

Autonomic Nervous System:

Answer 12

Motor Innervation of “internal body”

Cardiac muscle, smooth muscle, secretory glands

Subdivisions: Sympathetic and Parasympathetic

Question 13

Enteric Nervous System

Answer 13

Chains of ganglia (plexi/ plexus) along several layers of gastro-intestinal tube / alimentary canal.

Responsible for peristalsis and secretion of GI “juices”.

The neurons of the ENS are collected into two types of ganglia: myenteric (Auerbach’s) and submucosal (Meissner’s) plexuses.[10] Myenteric plexuses are located between the inner and outer layers of the muscularis externa, while submucosal plexuses are located in the submucosa.

Question 14

Dendrites

Answer 14

Receivers

Branches-most efficient receiving part in neuron for impulses and information.

Question 15

Soma

Answer 15

Perikaryon-around the nucleus

Major control place
Produces building blocks
Enables neurons to communicate with other neurons

Question 16

Node of ranvier

Answer 16

Gaps in the myelin sheath.

Appear at intervals along the axon.

Question 17

Neurons

Answer 17

carry/ transmit information by the conduction of electrical impulses / action potentials.

Question 18

Axon

Answer 18

Axis of a neuron.

Propagates nerve impulse toward another neuron, muscle fiber or gland cell.

Question 20

Synaptic end bulbs

Answer 20

Tips of some axon terminals

Chemical synapses found here

Question 21

Nissl bodies

Answer 21

Rough endoplasmic reticulum
Found in the soma

( neuronal cell bodies contain free ribosomes and prominent clusters of rer)

Question 24

Resting membrane potential

Answer 24

The membrane potential is an electrical voltage difference across the membrane.

VOLTAGE IS ALSO TERMED THIS.

Question 25

Neurons are electrically excitable and communicate with one another using 2 types of electrical signals.

Answer 25

• Action potentials.

- Graded potentials.

Question 27

Ion Channels

Answer 27

The main paths for flow of current across the membrane are ion channels.

When ion channels are open, they allow specific ions to move across the plasma membrane down their electrochemical gradient.

• Ions move from greater areas of concentration to lesser areas of concentration.
• Positively charged cations move towards negatively charged area and negatively charged anions move towards a positively charged area.
• As they move, they change the membrane potential.

Question 28

Types of Ion Channels

Answer 28

There are several types of ion channels.

Leakage channels - gates randomly alternate between open and closed positions.

Voltage-gated channels - open in response to change in membrane potential (voltage).

Ligand-gated channels - open and closes in response to a specific chemical stimulus.

Mechanically gated channels - open or closes in response to mechanical stimulation.

Light gated channels-open, when affected by entering light(eye retina)

Question 29

Resting Membrane Potential

Answer 29

In neurons, the resting membrane potential ranges from -40 to -90 mV.
Typically -70 mV.

The minus sign indicates that the inside of the cell is negative compared to the outside.

Question 30

Graded Potentials

Answer 30

A graded potential is a small deviation from the resting membrane potential. * It makes the membrane either more polarized (more negative inside) or less polarized (less negative inside). * Most graded potentials occur in the dendrites or cell body. Hyperpolarizing graded potential. Depolarizing graded potential. Graded potentials occur when ligand-gated or mechanically gated channels open or close. - Mechanically gated channels are present in sensory neurons. - Ligand-gated channels are present in interneurons and motor neurons.

Question 31

Action Potentials

Answer 31

known as an impulse. * Depolarizing phase - the resting membrane potential decreased towards zero. * Repolarizing phase - restores the resting membrane potential. Threshold - depolarization reaches a certain level (about -55 mV), voltage gated channels open. arise according to an all or none principal.

Question 32

Depolarizing Phase

Answer 32

A depolarizing graded potential or some otherstimulus causes the membrane to reach threshold • Voltage-gated ion channels open rapidly • The inflow of positive Na ions changes the membrane potential from -55mv to 30 mV. About 20,000 Na enter through the gates. Millions are present in the surrounding fluid.

Question 33

Repolarizing Phase

Answer 33

When all sodium channels are open, they will start slowly to close. Potassium voltage channels will begin to open. • K channels allow outflow of K ions. • The closing of Na channels and the slow opening of K channels allows for repolarization.

Question 34

Refractory Period

Answer 34

The period of time after an action potential begins during which an excitable cell cannot generate another action potential.

Question 37

Neurotoxins

Answer 37

Neurotoxins produce poisonous effects upon the nervous system. • Local anesthetics are drugs that block pain and other somatic sensations. • These both act by blocking the opening of voltage-gated Na channels and preventing propagation of nerve impulses.

Question 38

Continuous and Saltatory Conduction

Answer 38

Continuous conduction - step-by-step depolarization and repolarization of adjacent segments of the plasma membrane. • Saltatory conduction - a special mode ofimpulse propagation along myelinated axons. Few ion channels are present where there is myelin. • Nodes of Ranvier - areas where there is no myelin - contain many ion channels. • The impulse "jumps" from node to node. - This speeds up the propagation of the impulse. - This is a more energy efficient mode of conduction.

Question 39

Signal Transmission at Synapses

Answer 39

Presynaptic neuron - the neuron sending the signal. Postsynaptic neuron - the neuron receiving the message. * Axodendritic - from axon to dendrite. * Axosomatic - from axon to soma. * Axoaxonic - from axon to axon.

Question 40

Types of Synapses

Answer 40

Electrical synapse Chemical synapse

Question 42

Chemical Synapses

Answer 42

The plasma membranes of a presynaptic and postsynaptic neuron in a chemical synapse do not touch one another directly. The space between the neurons is called a synaptic cleft which is filled with interstitial fluid. A neurotransmitter must diffuse through the interstitial fluid in the cleft and bind to receptors on the postsynaptic neuron. The synaptic delay is about 0.5 msec.

Question 80

Axon hillock

Answer 80

Cone shaped elevation where the cell body is joined

Question 84

Axon terminal

Answer 84

Where the axon and collaterals end.

Question 92

Enteric plexus of meissner

Answer 92

Secretion

Question 93

myenteric plexus of auerbach

Answer 93

Motility

Question 99

What do ions produce

Answer 99

Electrical current

Question 156

Absolute refractory period

Answer 156

a second action potential cannot be initiated, even with a very strong stimulus.

Question 157

Relative refractory period

Answer 157

an action potential can be initiated, but only with a larger than normal stimulus

Question 180

Electrical Synapses

Answer 180

Action potentials conduct directly between adjacent cells through gap junctions.