nervous system <3

Neurons

structural and functional part → transmits via bioelectrical changes called nerve impulses

nerve impusles = action potiental

sent along nerve fibers (dendrites and axons)

*mature nuerons do not divide

    made of: soma, cytoplasm, cell membrane, cellular organelles, chromatophilic substance such as nissl bodies, large nucleus + nucleolus

Two Types of Nerve Fibers (Dendrites vs Axons)

• Dendrites: Receive incoming signals from other neurons and transmit them toward the soma.

• Axons: Conduct electrical impulses away from the soma to other neurons, muscles, or glands.

Types of Nerve Cells

1.) schwann cells (glial)

• Schwann Cells: Specialized glial cells that form the myelin sheath around axons in the peripheral nervous system, enhancing signal transmission efficiency.

2.) bipolar, unipolar, multipolar

    bipolar = sensory, ex: retina and olfactory bulb

    unipolar= sensory, ex: skin receptors, joints, ,muscles, internal organs

    multipolar= motor , exL brain or spinal cord

sensory = afferent

interneuron= association

motor= efferent

3.) neuroglial cell types

    1- oligiodendrocytes → hangs and makes mylen

    2- astrocytes → supports and regulate nutrients, constricts and dilates blood vessels (astro, think of astro world and peoples lifes being constricted and not supported)

Defects

• ischemia= oxygen deficiency from lack of blood flow

• hypoxemia= abnormally low blood oxygen levells

• prosopagnosia- facial blindness

• multiple sclerosis- autoimmune dirsorder in cns and pns

• alzheimer disease

• huntington disease

Nerve Impulse

nerve impulse has electrical depolarization

na+ into , K out

Brain structures

cerebrospinal fluid- clear watery

3 Main Parts of the Brain!!! →

Cerebrum (higher function)

1.) corpus callosum- connection between halves

2.) convolutions aka the gyri (ridges)

3.) sulci - grooves that divide into 4 lobes (frontal, temporal, occipital, parietal)

4.) fissure- deep groove

5.) cerebral cortex- outer layer

What does the cerebrum do?

higher brain functions, interprets sensory, initiates voluntary movement, stores info (memory), reasoning, intelligience and personaility

Diencephalon

Thalamus- central relay station of sensory info

Hypothalamus- maintains homeostasis functions ex blood pressure

Cerebellum (coordination)

(2 lateral hemispheres connected by vermis)

grey matter on surf, reflex center, coordinates cimplex skeletal muscle and posture_

Brain Stem (connection of nerves to cerebrum)

midbrain- visual and auditory reflex

pons- relays sensory info from peripheral nerves to higher brain

medulla- controls vitals

reticular activiating system- resposinvle for awakebing the cortex, samage will become comotose

longitudinal sulcus- divides into left and right halves

optic chiasm- optic nerves cross

Cranial Nerves (PNS)

numbers describe order, name describes primary function

1- olfactory (sensory)- smell

2.) optic (sensory) - vision

3- oculomotor (motor) - eyelid movement

4- trochlear (motor) move eyes

5- trigeminal (mixed) - fACE sensort and movement

6- abducens (motor) - move eyes

7- facial (mixed)

8- vestibulochlear (sensory) - equilibrium, hearing,

9- glossopharyngeal (mixed)- sensory and motor for mouth

10- vagus (mixed) -speech swallow

11- accessory (motor)

12- hypoglassal (motor) tounge

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reflex arcs

https://knowt.com/note/69bd13ea-77ea-4c65-b24f-d1f14d8310ce/nervous-system

1.) patellar tendon reflex

2.) bicep jerk

3.) tricep jerk

4.) achilles heel

5.) plantar reflex

receptor → cns → effecor (only uses two neurons)

(track to brain = ascending tract, tact to muscle = descending tracts)