hap 10-11 nervous system

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Neuorology

The branch of medical science that deals with the nervous system

CNS & PNS

The two Main divisions of the nervous system

CNS -The Central Nervous System

- consists of the brain and spinal cord - where sensory info is analyzed - generation of thoughts / emotions / impulses for muscle contraction / gland secretion

PNS - The Peripheral Nervous System

- cranial & spinal nerves
- carry impulses to / from CNS

Afferent neurons

transmit impulses toward CNS

Efferent neurons

transmit impulses away from CNS
E for exit

PNS is divided into 2divisions

Somatic Nervous System and the Autonomic Nervous System

Somatic Nervous System SNS

-sensory neurons for special sense receptors and
coetaneous (skin) receptors to CNS
(vision, taste, touch, pain, - voluntary - we are conscious of these)
- motor neurons transmit impulses to skeletal muscle

Autonomic (Automatic) Nervous System ANS

"Auto pilot" sensory neuron from things not aware of - involuntary
- sensor neurons from visceral receptors
- motor neurons to smooth muscle, cardiac, muscles ..and glands (body is aware, you are not ex: digestion of food)

Sympathetic Branch of PNS

expenditure of energy "fight or flight"
everything required to fight
or run for your life
kicks in automatically

Para-sympathetic Branch of PNS

conservation of energy
"feed or breed" all blood goes to digestion / no blood for breeding

Two Main Cell Types of the Nervous System

1. Neurons
2. Neuroglia

Neuroglia

helper cells to neurons -
different types and functions

Neurons

usually multiple dendrites
- Afferent process - transmits impulses toward cell body

Astrocytes

"star shaped" (astro-star)(cyte-cell)
metabolism of neurotransmitters-"like acytlcoline"
help to form blood brain barrier in CNS

Oligodendroctyes

Produce myelin sheath CNS
Physically support neurons by a gel matrix that they secrete "think of fruit suspended in a Jell-O mold"

myelin sheath

a layer of lipids (fats) & proteins
that surround the axons of some neurons

Microglia

Derived from (monocytes- a specific type of white blood cell)
"phagocytic"- it eats bacteria & cellular debris CNS

Ependymal Cells

line ventricles of brain and central canal of the spinal chord CNS

Schwann Cells

- produce myelin sheaths in the PNS

Satellite Cells

- support neurons in PNS Ganglia

Ganglia

- a collection of nerve cell bodies found in the PNS

Myelination

- myelin sheath is a layer of lipids and proteins that surround the axons of some neurons
- insulates the axon - speeds conduction time by arching between the Nodes of Ranvier

Synapse

- connection between 2 neurons or between a neuron and an effector

Nerve Fiber

- any neuronal process
- usually an axon

Nerve

bundle of nerve fibers (usually axons) located In the Peripheral Nervous System (PNS)

neuromuscular junction

types of synapses where the effector is "muscle"

neuroglandular junction

types of synapses where the effector is a gland

2 specific types of synapses

1. neuromuscular junction
2. neuroglandular junction

Tract

bundle of nerve fibers located in the (CNS)

Multipolar Neurons

- many dendrites - a single axon
- brain / spinal cord (mostly these)

Bipolar Neurons

- single dendrite - single axon
- usually assoc with special senses Rods / black & white
Cones / 3 types / red, blue, green

Unipolar Neurons

- "receptors" - single process

Afferent Neurons

- transmit toward CNS

Efferent Neurons

- transmit (exit) away from CNS

Association Neurons

-also called "Interneurons"
- relay impulses from one neuron to another- 90% of all neurons are Association Neurons

Neurophysiology

- Communication by neurons

2 basic properties of plasma membranes:

Resting Membrane Potential "RMP"
and Ion Channels

Resting Membrane Potential "RMP"

- an electrical charge / due to a separation of ions on each side of the neurons plasma membrane
-is maintained in part by ion pumps (active transport)

Anions

( - ) negatively charged ions inside neurons plasma membrane

Cations

( + ) positively charged ions outside neurons plasma membrane

Leakage Channel

- (one way doors) or Channels - always open in the
direction of RPM

Gated Channels

-Channels open or closed based on specific stimulus

the 4 types of gated channels:

Very Chilly Morning Light (picture frost on the gate at sunrise)
voltage, chemically, mechanically, light

Voltage Gated Channel

Channel opens to a response to a change in RMP

Chemically Gated Channel

Channel open or closed based upon a specific chemical (neurotransmitter)

Mechanically Gated Channel

Channel opens in response to pressure or vibration

Light Gated Channel

Channel opens in response to a specific wavelength (or color) of light

Depolarization

- open door in plasma membrane> in which channels open >
cations - / anions +
- has momentum

Move equalibrium of depolarization

-70mv > 0 > 30mv before moving back to -70mv

Repolarization

-Gated channels get closed
(RMP is restored)
-Use leakage channels 1st then ion pumps.

refractory period

The period of time before repolarization.

Saltatory Conduction

the arcing (or jumping) of action potentials along myelinated axons from one node of Ranvier to the next

speed of conduction along an axon is dependent upon the _______ of the fiber.

The "size" of the fiber.
The larger the fiber the faster the speed.

Stimulus intensity is a function of _____________.

frequency--all impulses are equal in strength, it is the frequency of impulses that create intensity

Name 2 Types of Synapses

Excitatory Postsynaptic Potential - (EPSP)
Inhibitory Postsynaptic Potential - (IPSP)

Excitatory Postsynaptic Potential - (EPSP)

- causes partial postsynaptic polarization of the postsynaptic membrane.
-with each EPSP the postsynaptic membrane is pushed closer to the threshold (summation)

Inhibitory Postsynaptic Potential - (IPSP)

hyperpolarization- the opposite of depolarization.
- at about 6 months of age neurons no longer undergo mitosis ( no new cells are formed )

Agonist

- a substance that mimics a neurotransmitter example: Caffeine

Antagonist

- a substance that blocks a neurotransmitter example: Novocain

Spinal Cord

- location within the vertebral canal of the vertebral column
- covered by a layer of protective tissue called meninges

Regions/ Layers of Meninges

Epidural Space, Dura mater, Subdural Space, Arachnoid mater, Subarachnoid Space, Pia mater

Dura mater

(dura-tough / mater-mother)
Outermost layer of meninges

Subdural Space

region between duramater and arachnoid-filled with interstitial fluid

Arachnoid mater

(spider legged) - Middle layer- arachnoid villi

Subarachnoid Space

between arachnoid and piamater- filled with cerebrospinal fluid

Pia mater

(pia-little / mater-mother)- Innermost thin membrane on surface of spinal cord

Epidural Space

- filled with fat & other connective tissue outside the duramater

Reflexes

- fast automatic responses - involuntary

Pathway

- route followed by impulses from origin to destination

Reflex Arc

- Simplest pathway

5 Functional Components of the Reflex Arc

1 Receptor, 2 sensory neuron, 3 integrating center 4 motor neuron 5 effector

Receptor

- (Unipolar Neuron) - responds to stimulus via EPSPS

Sensory Neuron

- relays impulses from receptor to spinal column

Integrating Center

- located within the CNS
- consists of 1 or more Association Neurons- may relay
impulses to cerebral cortex

Motor Neuron

- "Efferent Neuron" that sends impulse to body part that will respond

Effector

- body part that responds

if effector is skeletal muscle

Somatic Reflex -"since you are aware of it" (voluntary muscle)

if effector is visceral

Visceral Reflex -"Cardiac, stomach or gland"

Spinal Nerves-connect to CNS & PNS in 31 pairs
name & # in each set

8 pairs Cervical
12 pairs Thoracic
5 pairs Lumbar
5 pairs Sacral
1 pair Coccyseal

Spinal Nerves typically have 2 points of attachment to the spinal cord called roots; name them:

Anterior Root
Posterior Root

Spinal Nerves are covered by 3 types of protective C.T.- name them:

Epineurium, Perineurium, Endoneurium

Epineurium

protective c.t. - covers whole spinal nerve

Perineurium

protective c.t. -covers bundles of spinal nerve fibers (axons)

Endoneurium

protective c.t. - covers individual spinal nerve fibers

receptor is # ______

1

Effector is #

5

sensory neuron is #

2 carries impulse from receptor into cell body

Interneuron is #

6 between the sensory neuron and the motor neuron

cell body of sensory neuron #

3

motor neuron #

4 carries impulse from interneuron out to effector (muscle or gland)

central canal #

10

white matter #

11

dorsal area # (not 7)

8

spinal cord (#7)

7

gray matter #

12

ventral #

9

central canal #

4

posterior median sulcus #

2

Anterior funiculus #

5

Gray commissure #

3

portion of spinal nerve #

7

Anterior median fissure #

6

Posterior funiculus #

1

dorsal root of spinal nerve #

12

gray matter #

10

anterior horn #

15

lateral funiculus

11

dorsal root ganglion #

13

ventral root of spinal nerve

14

white matter

8

Posterior horn

9

Bipolar Neuron

has a single dendrite and a single axon

multipolar neuron

has multiple dendrites and a single axon

unipolar neuron

has a single axon

Schwann cells in PNS and oligodendrocytes in CNS

the neuroglial cells responsible for forming myelin sheaths around axons

Cerebellum

The brain stem consists of the

The brain stem

connects the spinal cord to the remainder of the brain

damage to the brain stem

is usually fatal.

the brain stem controls many

essiental functions

autonomic and somatic

the divisions of the periferal nervous system

the parasympathetic branch of the nervous system

deals with activities that are involved in the conservation of energy.

medulla and pons

the 2 parts of the brain involved in controlling respiration

voltage gated channels open in response

to a change in RMP.

thalamus

the largest portion of the diencephalon

pons

the part of the brain located between the medulla and the mesencephalon

cranial and spinal nerves

what does the periferal nervous systen consist of?

multi

Most of the neurons in the CNS and most motor neurons are -----polar neurons

"involuntary"

reflexes are fast _______responses

chloroid plexuses form

cerebrospinal fluid

To seperate the brainstem from the rest of the brain, I would need to make a cut

above the mesencephalon(top of brain stem) and below the diancephalon(inferior part of the brain)

neuroglia also serves as

the major supporting tissue in the cns

After plasma goes through the endothelio cells a second filtration of plasma by neuroglia results in

the formation of the blood-brain barrier

refractory period

the period of time during which a neuron cannot generate another action potential

postsynaptic membrane

in an excitatory postsyaptic potential the _________ becomes partially depolarized

mechanically gated

a specific type gated ion channel thar responds to pressure or vibrations.

anions

In RMP ther is a build up of ______
"inside" the plasma membrane.

are located in the medulla

centers to regulate reflexes such as breathing, swallowing, vomiting, coughing, and sneezing

hypo-thalamus

Symptoms of irregular body temperature, intense thirst, lack of appetite, might indicate a disfunction of what part of the brain

Perinerium

bundle of nerve fibers

lobes of the cerebrum

occipital, temporal, frontal,parietal

Afferent neurons send impulses

toward the CNS

Leakage channels

ion channels that are always open

rami-singular/ramus-plural

After passing through the intervetebral foramem spinal nerves branch. These branches are called _______________.

3 types of Rami

1. Dorsal Ramus
2. Ventral Ramus
3. Meningeal Branch

Dorsal Ramus

- controls dorsal (back) structures

Ventral Ramus

-controls ventral (front) structures

Meningeal Branch

- re-enters the intervetebral canal and serves the vertebra & the meninges

Ventrarami

- form networks, or "Plexuses",

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