BIO 233 Unit 7 (Set # 2) Lecture Exam Material

Central Nervous System (CNS)

consists of the brain and spinal cord

autonomic nervous system

Controls involuntary activity of smooth muscle, cardiac muscle, and glands

afferent neurons

carry sensory information to CNS

efferent neurons

Nerve cells that conduct impulses away from the central nervous system

Interneurons

these process sensory and motor impulses--only within brain and spinal cord (CNS)

multipolar neuron

a nerve cell that has many dendrites and a single axon (most motor neurons and interneurons)

unipolar neuron

cell body located to side of axon--most afferent sensory neurons

Nissl bodies

Rough endoplasmic reticulum in neuron

synapse

the site of intercellular communication between a neuron and another cell

Which type of neuron is most numerous in CNS?

Interneurons

astrocytes

help form blood brain barrier

ependymal cells

line cavities of the brain and spinal cord, circulate cerebrospinal fluid

Microglia

Act as phagocytes, eating damaged cells and bacteria, act as the brains immune system

electrochemical gradient

The combination of forces that acts on membrane potential.

Voltage-gated sodium channels are located where on a neuron?

On the axon

Ligand -gated sodium channels are located where on a neuron?

On the dendrites

Ligand-gated channels on a neuron produce _________ potential/s.

graded

Voltage-gated channels on a neuron produce _________ potential/s.

Action (if they add up to threshold)

axon hillock

Cone shaped region of an axon where it joins the cell body--summation of potentials occurs here

saltatory propagation

the movement of an action potential along a myelinated axon, "jumping" from node to node

Type A fibers

Myelinated

Large diameter

High speed (140 m/sec)

Carry rapid information to/from CNS

For example, position, balance, touch, and motor impulses

Type C nerve fibers

Unmyelinated

Small diameter

Slow speed (1 m/sec)

Carry slower information

For example, involuntary muscle, gland controls

absolute refractory period

time during which another action potential is impossible; limits maximal firing rate

relative refractory period

a stronger than usual stimulus is necessary to initiate an action potential

EPSP (excitatory postsynaptic potential)

Excitatory--makes cell more positive--Synaptic potential that makes a postsynaptic neuron more likely to generate an action potential

IPSP (inhibitory postsynaptic potential)

Inhibitory--makes cell more negative--synaptic potential that makes a postsynaptic neuron less likely to generate an action potential

Synaptic delay is caused by

calcium influx (into pre-synaptic terminal bulb), and neurotransmitter release.

Steps at cholinergic synapse

1) action potential arrives
2) Ca2+ enters, triggers release of ACh
3) ACh released, binds to receptors
4) post synaptic cell depolarizes

What is another name for IPSPs?

Graded hyperpolarizations

The effect that a neurotransmitter has on the postsynaptic membrane depends on the _______.

specific properties of the receptor proteins

dorsal root ganglion

contains cell bodies of sensory neurons

most common type of synapse in the body

chemical synapse

Least common type of synapse in the body

electrical synapse

Steps of Reflex Arc in order:

1. Arrival of stimulus and activation of receptor
2. Activation of a sensory neuron (Afferent)
3. Information processing in CNS (Interneurons)
4. Activation of a motor neuron (Efferent)
5. Response by effector

Contralateral

on the opposite side of the body

Ipsilateral

on the same side of the body

endoneurium, perineurium, epineurium

Layers of connective tissue of a nerve from interior to exterior

ascending white columns

carry sensory information up to brain (consist of myelinated axons)

descending white columns

carry motor information from brain to motor neurons in PNS (consist of myelinated axons)

Spinal nerves contain

both sensory and motor fibers

dorsal root

the sensory branch of each spinal nerve

ventral root

contains axons of motor neurons

somatic nervous system

Division of the PNS that controls skeletal muscles.

Schwann cells

produce myelin in PNS

myelin sheath function

insulates axon and speeds up conduction

GABA --inhibitory or excitatory? How does it affect anxiety?

inhibitory, decreases anxiety

spinal tap (lumbar puncture)

Procedure performed by using a needle to withdraw CSF --fluid drawn from subarachnoid space

epidural anesthesia

used in vaginal live child birth because it blocks much of the pain from sensory nerves in pelvic region (only blocks sensory)

how many pairs of spinal nerves?

31 pairs

3 ways that neurotransmitters are removed from the synaptic cleft are _______.

1. degradation by an enzyme
2. simple diffusion away from cleft
3. re-uptake via active transport

Opioids

Any drug or agent derived from opium. Effective at blocking pain, but highly addictive.

fentanyl

Extremely powerful opioid

Synapses that release acetylcholine are called _________ synapses.

cholinergic

Cerebral-spinal fluid (CSF) circulates in which 3 areas of the CNS?

1) brain ventricles, 2) central canal of spinal cord, 3) subarachnoid space

Which nerve controls movement of the diaphragm, affects respiration, and results in hiccups when it spasms?

phrenic nerve

monosynaptic reflexes

-The simplest of all reflexes
-No interneurons
-The stretch reflex is an example (patellar or knee jerk reflex)

endorphins

released during exercise and blocks or inhibits pain

polysynaptic reflex

at least one interneuron between sensory neuron and motor neuron

Why are there so many opioid related deaths?

Because opioids affect the brainstem, which can result in depressed or slowed breathing

autonomic reflexes

regulate the activity of smooth muscles, the heart, and glands

action potential

Be able to label and discuss the steps of an action potential in a graph similar to this