Exam 3

What is the anatomical division of the nervous system?

CNS and PNS

What does the peripheral nervous system contain?

cranial nerves and spinal nerves

what does the central nervous system contain?

brain and spinal cord

What is the division of the peripheral nervous system?

Afferent (sensory)

Efferent (motor)

What does nervous tissue contain?

neurons and glial cells

What are the structural classifications of neurons

anaxonic, bipolar, multipolar, unipolar

What are the functional classifications of neurons?

SIM

Sensory

Interneurons

Motor Neuros

What are sensory neurons?

neurons that carry incoming information from the sensory receptors to the brain and spinal cord

What are inter neurons?

process sensory information from afferent neurons and sending commands to efferent neurons.

What are motor neurons?

neurons that carry outgoing information from the brain and spinal cord to the muscles and glands

What are anaxonic neurons?

Small, cannot tell axons from dendrites, brain.

What are bipolar neurons?

one axon and one dendrite (special organs=rare)

What are multipolar neurons?

Common in the CNS, have very long axons, multiple dendrites but only one axon.

What are unipolar neurons?

sensory neurons grouped in ganglions

What is the CNS Neuroglia?

astrocytes, microglia, ependymal, oligodendrocytes

What are astrocytes?

blood brain barrier

What are microglia?

phagocytes that remove debris

What are ependymal cells?

gilial cells that form epithelium

What are oligodendrocytes

produce myelin in CNS

What is white matter?

myelinated axons (myelin insulates axon

What is gray matter?

mostly neuron cell bodies and nonmyelinated fibers

What are the neuroglia of the PNS?

Schwann cells and satellite cells

What are Schwann cells?

form myelin sheath in PNS

What are satelite cells and what do they do?

myoblasts fuse to make new fibers (repair small segments)

What are the 3 factors that make a membrane potential at rest?

active process (Na + K exchange pump (req ATP )

K leak channels

ICF neg charged proteins

What is the sodium-potassium exchange pump?

- Is an active process across the membrane that is powered by ATP

- It ejects 3 Na+ for every 2 K+ brought in

- Stabilises the resting membrane potential of -70mV

When in the absence of a pump what are the alternatives?

Chemical and electricl gradients

Sodium at rest is

very weal inward ionic+ few opeak leak (ALIGNED)

Potassium at rest is?

many leak channels

What is action potential?

a neural impulse; a brief electrical charge that travels down an axon

What is resting membrane potential?

-70mV

What is the 2nd step for an action potential?

depolarization phase: sodium volt gates are activated and opening (MORE POS)

What is the first step for an action potential?

action potential arrives

What is the threshold for action potential

-55mV

What is the 3rd step of an action potential?

Absolute refractory phase: (repolarization): sodium volt gates are inactivated and K+ volt gates are now open (MORE NEG)

What is the 4th step of an action potential?

hyperpolarization: sodium volt gate channels are now closed

and K+ volt gate pumps are still active

What is the refractory period?

a period of inactivity after a neuron has fired

What are the two types of refractory?

absolute and relative

What is an absolute refractory period?

The period of time in which another Action Potential cannot be created (peak)

What is the relative refractory period?

the period shortly after the firing of a nerve fiber when partial repolarization has occurred and a greater than normal stimulus can stimulate a second response (ending)

What is propagation?

The continuation of a nerve impulse

What are the steps for propagation?

1. AP arrives

2. depolarized

3. AP develops at nodes

4. local current produces a graded depolarization to axolemma at node to threshold

Which of the fibers is fastest?

Type A ( 120 m/sec) (myelinated

What are the types of fibers?

Type A

TYPE B

TYPE C

which of the fiber is second fastest?

type B (18 m/sec)

Which of the fiber is the slowest?

Type C ( unmyelinated)

What is postsynaptic potentials

graded potentials developed in a postsynaptic cell in response to neurotransmitters

What are the 2 types of postsynaptic potentials

Excitatory postsynaptic potential (EPSP)

Inhibitory postsynaptic potential (IPSP)

What is temp summation

ESPS1+ESPS2= Action potential

What are synapses

gaps between neurons

What are the two synapses

electrical and chemical

What are electrical synapses

direct physical contact between cells

What are chemical synapses?

Signal transmitted across a gap by chemical neurotransmitters

What is the steps of cholinergic synapse?

1. AP depola the axon terminal membrane of presyn neuron

2. ecf calcium ions enter axon terminal volt gate ca trigger exocytosis of ACh

3. Synaptic delay (.2-.5)

4. Synaptic fatigue: neurotransmitter recycliing

What do neurotransmitters on post synaptic membranes depend on ?

properties of receptors

What are the major classes of neurotransmitters?

amino acids, monoamines, peptides

Why do we have two enlargements

To support the upper limbs

And lower limbs

What are Mengines?

the three covering layers of the brain

What are the three covering layers of the brain

Pia,dura,arachnoid

White ramus communicans+gray ramus=

autonomus NS

What are mixed nerves?

both sensory and motor fibers

What is posterior ramus

the smaller of the two main branches and innervates the deep muscles of the back and the skin of the back

What is the anterior ramus?

supplies mos of body wall, skin, limbs

What does dura mater connects with?

coccygeal ligament

What is the epidural space?

space between vertebrae and dura mater

What is the Archnoid Mater?

middle layer of the meninges

What is cerebrospinal fluid?

the fluid that surrounds the brain and spinal cord

What does the pia matter connecgs

denticulate ligaments

What does gray matter contain?

neuron cell bodies, neuroglia, unmyelinated axons

What does white matter contain?

myelinated axons

What gray matter zones ?

posterior horns

anterior horns

lateral horns

What is the posterior horns?

receives and transmits sensory impulses

WHat is the anterior horns

cell bodies of somatic motor neurons

What is lateral horns

thoracic+ lumbar segments

What is white matter composed of?

bundle axons

What is the division of white matter

ascending+ descending tracts

What is the ascending tract

carry sensory signals up the spinal cord

What is a descending tract?

carry motor signals down the brainstem and spinal cord

What is spinal nerves

anterior root consists of motor neurons from anterior horn, posterior root consists of sensory neurons from posterior horn, all 31 pairs of spinal nerves are mixed nerves