Intro into Neurophysiology

1.Be able to distinguish the central nervous system (CNS) from peripheral nervous system (PNS).

• CNS- brain and spinal cord

  • collection of neurons= nuclei

• PNS- nerve fibers go tal all parts of the body

  • send signals to the diff tissues and sent signals back to CNS

  • collection of neurons = ganglion

2. What is the most common type of cell in the nervous system?

• glial cells

3. A common function of glial cells is to insulate neuronal axons. What is different about the glial cells provide this support in the CNS vs. PNS?

• In the PNS they support cell bodies and secrete neutrophil factors

• In the CNS they provide substrates for ATP production, help form blood brain barriers, secrete neurotrophic factors, create barriers between compartments

4. Be able to label the parts of a neuron and understand the direction of electrical conduction.

5. What are the three main processes necessary for neuronal signaling?

• graded potential

  • input signal

• action potential

  • conduction potential

• synaptic signaling

6. What is voltage?

• a difference in electrical potential

• tells us something about the amount of work that can be done

• negative v= relative excess of electrons

• positive v= relative deficiency of electrons

7. How does the Na+/K+ ATPase create the resting membrane potential of a neuron?

• it moves 3 Na+ out and it brings Ka+ in

8. What is a graded signal?

• they integrate input and determine if signal will be passed on

• proportional to stimulus strength

• more receptors triggered = more gates open = depolarization

Polarization vs depolarization

• De= away from the pole

9. What is impulse dissipation and how might it relate to temporal summation?

• Why does it dissipate?

  • Current leakage, cytoplasmic resistance, number of Na+ gates opened

• If two sub threshold potentials arrive at the trigger zone within a short period of time, they may sum and create an action potential

10. What is the important event or functional role of the axon hillock?

• if a graded potential reaches it, voltage gated Na+ channels open

• its the place where the axon emerges from the cell

11. Compare and contrast graded vs action potentials using Table 8-3.

12. Fully understand the steps of the action potential, the proteins involved, and the step-wise movement of the important ions.

• Resting potential:

  • na+ is higher outside the neuron,

  • while K+ is higher on the inside.

  • Na+/K+ pump is always working

• Depolarization:

  • The Na+ channel open and the Na+ enters the neuron.

  • The interior becomes + and the outside become -

• Peak Depolarization:

  • Na+ channels close,

  • K+ channels open and K+ leave the neuron

  • highest depolarization

• Return to resting potential: -

  • Same charge as initial

  • on the inside and + on the outside ,

  • the ions are switched,

  • and need to return to the proper resting potential

13. Why is an action potential unidirectional and/or what causes the refractory period?

• Frequency of action potential directly proportional to stimulus intensity

• Larger diameter axons conduct action potentials faster than smaller diameter

• Myelinated axons conduct action potentials faster than unmyelinated axions

14. How can a neuron communicate differences in stimulus intensity?

• Frequency of action potentials is proportional to stimulus intensity

15. How and why does axon diameter influence the speed/efficiency of neuronal signaling?

• Larger diameter axons conduct action often tails faster than smaller diameter axons

16. How does myelination influence the speed/efficiency of neuronal signaling?

• it insulates it and the signal doesnt NEED to travel all the way through the axon

17. What is saltatory conduction?

• ion channel opening/closing slows conduction

• myelination increases insulation, decreases leakage, therefore can get away with fewer channels

18. What is the Babinski reflex and how does it involve myelination?

• It's where you big toe bends backward and the others go forward. It happens by the time your 2 years old and to adulthood which means there normal development of full myelination

19. Describe the steps of synaptic transmission.

• Action potential depolarizes the axon terminal

• The depolarization opens voltage gated Ca+ channels and Ca2+ enters the cell

• Calcium entry triggers exocytosis and synaptic vesicle contents

• Neurotransmitter diffuses across the synaptic cleft and binds with the receptors on the postsynaptic cell

when a pre-synaptic neuron releases a chemical messenger what is it targeting on the post-synaptic cell

answer: Chemically-gated messenger

20. What makes an neurotransmitter excitatory vs. inhibitory?

21. Name two different ways cells can actively regulate signals in the synapse.

22. What are the cellular mechanisms involved in long-term potentiation? [i.e. What does the post-synaptic cell do and how might the pre-synaptic cell respond to “strengthen the synapse”.]

• • Glutamate binds to AMPA and NMDA channels
  • Na+ entry through AMPA Chanel's depolarizes the postsynaptic cell
  • Depolarization ejects Mg2+ from NMDA exceptional channel and opens channel
  • Ca2+ enters cytoplasm through NMDA channel
  • Ca2+ activates second messenger pathways
  • Paracrine from postsynaptic cell enhances glutamate release

23. Describe the physiological switch controlling hormonal regulation of circadian rhythm.

24. Name and describe three mechanisms of signal integration.

• Spatial summation: excitatory neurons fire and the graded potentials are below the threshold, they arrive at the trigger zone and the action potential is generated.

• Temporal summation; one inhibitory a two excitatory neurons fire, the potentials are below the threshold so no action potential is generated

• Long term potentiation: there is positive feedback and increased post synaptic activity, it strengthens the synapses which is important for learning/memory

Effects of 5-HT in humans (serotonin)

-bowel function= decreasing hunger while digesting

-mood= anxiety and happiness

-too little: eating disorders, panic atacks, OCD

-too much: anxiety, depression, insomnia, decreased libido, GI disorders

Central Nervous System

1. What is a nerve?

2. What is an afferent pathway? What is an efferent pathway?

• afferent

  • input

  • Away from the periphery

  • somatic sense, special, visceral

• efferent

  • Output

3. Understand the basic organizational scheme of somatosensory input and motor output.

• (afferent input)→ CNS→ Somatic or autonomic response (efferent output)

4. Name three general types of structures used to protect the central nervous system.

• bony tissue

  • cranium

  • spinal cord

• membranous tissue (meninges)

  • dura matter

  • arachnoid membrane

  • pia matter

• blood CSF barrier

• Blood brain barrier

5. What cellular feature is used by ependymal cells in the choroid plexus AND by cells forming the blood vessels delivering blood to the brain?

• they line internal cavities of brain & spinal cord. form choroid plexus with nearby blood capillaries, Helps produce cerebrospinal fluid (CSF), Liquid that bathes CNS and fills its cavities

• cerebrospinal fluid

6. Why is the color of fluid from a spinal tap a potentially useful diagnostic for disease?

• it could be indication of elevated WBC if more yellow

• brown could be brain bleed

7. What is white v grey matter in the nervous system and how does their distribution differ between the brain and spinal cord?

8. Be familiar with the man parts of the brain and their general functions.

• brain stem

  • connects brain to spinal cord

• cerebellum

  • little brain

  • processes sensory info

  • input from body recepetors, also inner ear

• diencephalon

  • thalamus, hypo, pituitary gland, pineal gland

• cerebrum

  • basal nuclei (ganglia)

  • limbic system

  • cerebral cortex

  • higher brain function, language, sensory integration, motor poutput

  • memory

• 

9. What is cerebral lateralization (i.e. asymmetric brain specialization)?

• cut the brain in half and see how different areas are split up

10. What are three basic methods to study specialization of the human brain?

• use animal models

• take advantage of accidents

• brain imaging

11. Describe how an EEG works.

• free electrons in the metal electrodes respond to the flow of ions in and out of neurons

AUTONOMIC SYSTEM

1. What is the autonomic nervous system?

• control involuntary responses

2. What are the main divisions of the autonomic nervous system? Compare and contrast the two main divisions.

• sympathetic division

• parasympathetic

3. Be aware of the types of sensory input that might cause changes in autonomic pathways. (i.e. homeostatic control centers in the brain receive input from general sensors distributed throughout the body)

• sensory input from somatosensory and visceral receptors

4. What is similar about sympathetic and parasympathetic pathways?

• both use acetylcholine

5. What are three differences between sympathetic and parasympathetic pathways?

• para sympathetic = rest and digest

• sympathetic= fight or flight

• 1. postganglion neurotransmitters and effector targets

• 2. anatomical differences:

  • point of origin from CNS

  • thoracolumbar

  • craniosacral

• 3. anatomical differences:

  • length of preganglionic vs postganglionic neurons

6. How does the anatomical arrangement of sympathetic pathways facilitate “mass activation”?

• because theyre all in line

• sympathetic paravertebral ganglion stimulates mass activation due to short preganglionic fibers with extensive branching, facilitates activation of many structures

7. What is dual activation?

• reaches and targets same organs and compete for control/shifts.

8. Name an example of the antagonistic effects of sympathetic vs parasympathetic activation. What is an exception to the general rule of antagonistic effects?

• The sympathetic division speeds up heart rate while the parasympathetic slows it down. Reproduction is kinda an exception

9. How is it possible that both the autonomic nervous system (involuntary control) and the somatic nervous system (voluntary control) can target muscles using the same neurotransmitter (i.e. acetycholine)? How can the same signal cause different responses and be used to control different things?

• Different receptors on the the target tissue allow for the same signal to cause different responses

10. Why might sympathetic neurons not use breakdown enzymes to regulate synaptic transmission?

• PANS or breakdown enzymes aren't as effective for the sympathetic nervous system. SANS or the action of reuptaking signals is much more effective in the sympathetic nervous system

SENSORY SYSTEMS

1. Be able to differentiate general and special senses.

--- Are there differences in their pathways to the CNS?

• Special senses are confined to

  • head; eyes ears, nose, and mouth.

  • olfaction&gustation use chemoreceptors

• General

  • sense are receptors widely distributed throughout the body. skin. various organs and joints.

  • somatic

  • no specialized sensory organs

  • transmitted to CNS via afferent (somatic) neuron

2. Compare and contrast different types of sensory neurons.

• simple

  • neurons with free nerve ending

  • have myelinated or unmyelinated axons

• complex

  • have nerve ending enclosed in connective tissue capsules

• nonneural

  • most special senses are non neural cells that release neurotransmitter onto sensory neurons, initiating an action potential

1. Be able to differentiate general and special senses.
- Are differences in their pathways to the CNS?
2. Compare and contrast different types of sensory neurons.