• 3 main functions

  1. sensory functions

     1. senses changes in and around your body

  2. Intergrative functions

     1. processing and analyzing sensory functions

        1. short term or long-term

        2. you technically don’t forget anything

  3. Motor functions

     1. response to sensory and intergrative functions

• Study of nervous system = neuroscience

  • these 4 are specific focuses of neuroscience

  1. neurology (medical)

  2. neurobiology (biological)

  3. neurophysiology

  4. neuroanatomy

CNS and PNS

• CNS

  1. brain

  2. spinal cord

• PNS (peripheral)

  • sensory functions controlled by this

  1. nerves

     1. sensory (afferent) nerves

        1. sensation and transport to CNS (body to CNS)

     2. motor (efferent) nerves

        1. responses (CNS to body)

        2. somatic nervous system

           1. deals with skeletal muscle

           2. voluntary

        3. autonomic nervous stsem

           1. smooth and cardiac muscle

           2. involuntary

           3. 2 parts

              1. sympathetic division

                 1. fight or flight

                 2. controls heart, lungs

              2. parasympathetic

                 1. feed and breed

                    1. not life and death things

                 2. controls stomach, intestines, etc.,

Cell Types

1. Neurons

• direct movement, memory, sense

• unable to perform mitosis

  • so born with more, those not used perform apoptosis

    • if you don’t use it, you lose it

    • reason why babies should be coddle, etc. so important neurons don’t die

• giant cells (compared to cellular kingdom)

  • visible to naked eye

• Parts of the neuron

  1. Soma

     1. regular cell

  2. Dendrites

     1. branch-like

     2. receives messages

  3. axon

     1. goes to specific place

  4. synapse

     1. space between neuron and dendrites of other neuron

     2. neurotransmitters - tell the next neuron to fire/do their job

• Action Potential

  • impulse/signal/electricity that runs through the neuron

  1. Resting membrane potential

     1. potential for energy to be relayed

     2. 2 chemicals - (have +1 charge)

        1. Na

           1. high on outside, low on inside

        2. P

           1. low outside, high inside

           2. not a lot of P in cell compared to Na

     3. resting potential= -70 mV

  2. Depolarization

     1. resting potential = goes towards positive, as high as 30 mV

     2. Na channels open and Na rushes to the inside

        1. charge gets positive

     3. -55 mV = threshold

        1. if signal sent is below -55mV, body won’t consider important

  3. Repolarization

     1. K channels open

        1. K rushes outside

        2. mV charge starts dropping down again

           1. if drops enough, reach hyperpolarization = as low as -90mV

     2. how to go back to resting membrane state? - Na/K/ATP pump

        1. pumps out 3 Na for every 2 K

           1. sets up imbalance again

2. Neurogilial

• keep neurons healthy and alive

• maintain fluid that surrounds neurons

• make up about half of nervous system as adult, babies have very few

• way more gilial cells than neurons

• gilial cells are what cause brain cancer

1. astrocytes

   1. Job: metablize neurotransmitters

      1. insure neurotransmitters aren’t hanging outside the cell longer than they need to

   2. Job: prevent potassium imbalance

   3. Job: brain development, BBB (blood-brain barrier)

   4. most common of neuroglial cells

2. oligodendrocytes

   1. smaller than astrocytes

   2. few processes

   3. wrap around neurons and secrete material called myelin

      1. myelin forms myelin sheath

      2. myelin is insulation for neurons and make sure signals go where they need to

3. microglial cells

   1. very small

   2. destroys any dead, damaged cells and foreign cells

4. ependymal

   1. epithelial cells

   2. help make, maintain CSF (cerebrospinal fluid)

5. neurolemmocytes (Schwann cells)

   1. secrete myelin sheath

   2. MS - disease related to lack of myelin covering

6. Satellite cells

The Brain

• approx. 100 billion neurons

• Parts of the Brain:

  1. Brain stem

  2. Cerebellum

  3. Dioncephalon

     1. sits in the middle/center of the brain

  4. Cerebrum

1. Cranial meninges

   1. connective tissue that holds everything together

   2. outer layer = dura mater

      1. literally means “tough mother”

   3. arachnoid - spider web-like

   4. pia mater = inner layer

      1. contact with brain tissue and spinal cord

      2. blood vessels and collagen

   5. disorder = meningitis (bacterial and virus)

2. CSF (cerebrospinal fluid)

   1. provides nourishment and protection of the brain

   2. fills inner and outer holes

   3. clear and colorless

   4. 50-100 milliliters

   5. contains things like glucose and protein + waste products (urea) + ions

   6. 3 main functions

      1. mechanical protection

      2. chemical protection

      3. circulation

3. Blood supply

   1. carries oxygen and glucose

   2. brain uses about 20% of blood supply

      1. needs alot of oxygen and glucose

   3. need constant supply of blood and glucose

   4. capillaires spread out around pia mater and dump blood

   5. Blood Brain Barrier (BBB)

      1. selectively permeable

         1. very permeable to oxygen, CO2, glucose, urea

            1. also caffeine, nicotine, anaesthesia, meth, etc.

               1. mimics neurotransmitters like endorphin

         2. blocks

Brain Stem

1. Medulla oblongata

   1. most inferior part (closest to spinal cord)

   2. cardiovascular center

   3. breathing rate control

   4. controlls swallowing, coughing, vomiting, hiccuping, etc.

2. Pons

   1. means bridge

   2. sits on top of medulla, below cerebellum

   3. relay center between right and left side

3. Midbrain

   1. reflex

   2. coordinates muscle movement

   3. relays info to thalamus abt touch, pressure

4. Reticular formation

   1. sets muscle tone

   2. maintaining conscienousness

Cerebellum

• Function: constantly analyzing what’s happening and what you think is happening

• controls skilled activities (like athletics)

• regulate posture and balance

• complex skeletal movement

• Proprioception - Ability to tell where something is making contact

Dicephalon

1. thalamus

   1. 80% of dicephalon

   2. relay station for any signal in body to be sent to appropriate place

   3. allows us to appreciate pain, pressure, temperature changes

   4. allows for acquisition of knowledge (ability to learn)

2. hypothalamus

   1. most important part of the brain

   2. located in the center of the brain

   3. involved in

      1. sound, taste, smell initially come here

      2. blood temp.

      3. hormone concentration

      4. blood pressure

      5. autonomic nervous system

      6. controls pituitary gland which produces horomones (that do lots of various things)

      7. body temp.

      8. emotions and behavior regulation

      9. regulation of sleep patterns

3. Epithalamus

   1. Tiny gland called the pineal gland

      1. produces melatonin

Cerebrum

• outer part of the brain

• right and left hemisphere

• outer layer - gray matter

• inside layer - white matter

  • gyrl

    • twisty, wormy stuff

  • sulci

    • shallow grooves

  • fissures

    • deep grooves, separate different lobes

    • Corupus collosum

      • communication between right and left side

1. Frontal

   1. motor function

      1. including speech

2. Parietal

   1. gustation (taste)

3. Temporal

   1. olfaction (smell)

   2. audition (hearing)

   3. understanding speech

4. Occipital

   1. vision

• Limbic System

  • involved in emotional response and memories

  • determines difference pressure and pain, fear and anxiety, etc.

  • the chemical for nervousness is the same as excitement but our mindset determines how we interpret it

The Eye

• Sclera - white stuff

  • turns red and pink cause of blood (tiredness causes redness)

• Cornea - bulge on the front of the eye

• Iris - colored part

  • most common - brown, blue, green

  • a sphincter muscle - open or close (control size of opening)

• Pupil - opening in the iris

• Lens - bends the light

  • sits right behind the eyes

  • movable - controlled by muscles on top and bottom

    • changes shapes based on what is being focused on

  • Disorder - cataracts

    • lens gets foggy

    • inevitable for all people

    • lens replacement surgery

• Retina - where images are received

  1. Rods

     1. evenly dispersed

     2. detect black and white/light and dark

  2. Cones

     1. centralized in the middle

     2. less of these than rods

     3. detect color

• Aqueous humor - maintains shape of cornea

  • disorder - glaucoma (production of too much aqueous humor)

    • treatment

      1. narcotics

      2. needle drain

      3. marujana

• Vitreous humor -

  • maintains pressure and shape of eyeball

• Disorders

  • astigmatism

    • uneven curve of eyeball

  • myopia

    • near-sightedness

    • eyeball too long, image processed too fast

  • hyperopia

    • far-sightedness

    • eyeball too short/round, object focuses too late

  • presbyopia

    • old eye

    • lens stops working as good since muscles are worn out

The ear

• part of the auditory system

• Auricle/Pinac - outer ear

  • cartilage covered by skin

  • purpose: funnel sound into ear canal

  • Age - cartilage and hair grows

• Ear canal (auditory canal)

  • curved to prevent water entrance

• Tympanic membrane (eardrum)

  • earwax keeps it moving

• Malleus, incus, stapes

  • smallest bones in the body

• Oval window

  • presses and releases to create pressure changes in cochlea

• Cochlea

  • thousands of tiny hairs send messages to temporal lobe based on pressure changes

• Semi-circular canals (don’t help with hearing)

  • fluids in canal help with balance and body position

• Eustachian Tube

Disorders

• Deafness

  • tone deaf (not a real disorder) - hairs that determine pitch aren’t precise

  1. Conductive deafness

     1. something wrong with machinery

        1. Ex: damage to eardrum or malleus, incus, stapes

     2. easily fixable with surgery

  2. Nerve deafness

     1. something wrong with cochlea/neurons

     2. traditionally unfixable, but modern science has been able to fix some forms of nerve deafness

  • issue: born with deafness means neurons will likely die