nervous system anatomy

dendrites

receive signals from other cells

cell body (soma)

contains nucleus and controls cell

axon

carries impulse away from cell body

myelin sheath

a protective, fatty membrane that wraps around nerve cell axons, serving as electrical, insulation to increase the speed of electrical impulse transmission

nodes of ranvier

axon terminals

release neurotransmitters to next cell

dendrites in or out

in

axon in or out

out

central nervous system (CNS)

includes brain and spinal cord and is main control center

peripheral nervous system (PNS)

includes all nerves outside brain and spinal cord and carries messages to/from CNS

sensory (afferent) divison

carries information to CNS

ex: touching something hot

motor (efferent) division

carries commands from CNS to body

ex: moving hand away

afferent

arrives

efferent

exits

motor division split: somatic nervous system

voluntary control, controls skeletal muscles

walking, writing

motor division split: autonomic nervous system

involuntary, controls smooth muscle, cardiac muscle, glands

heartbeat, digestion

sensory neurons

carry signals from receptors to CNS

association neurons (interneurons)

inside CNS, connect neurons

motor neurons

carry signals from CNS to muscles/glands

impulse path

receptor —→ sensory neuron —→ interneuron —→ motor neuron —→ effector

white matter

myelinated fibers, faster signal transmission

gray matter

cell bodies + unmyelinated fibers, processing area

how myelin helps speed

myelin lets impulse jump node to node, this is called saltatory conduction. much faster than traveling whole axon

reflex arc sequence

order: receptor, sensory neuron, interneurons motor neuron, effector

ex: touch hot stove —→ hand pulls away

somatic reflex

controls skeletal muscle

ex: knee jerk

autonomic reflex

controls organs/glands

ex: heart rate, pupil size

brain description

it weighs 3 pounds and contains about 86 billion neurons

cerebral hemispheres: occipital lobe

vision

cerebral hemispheres: temporal lobe

hearing + memory

cerebral hemispheres: primary motor area

controls voluntary movement

cerebral hemispheres: broca’s area

speech production

Diencephalon: thalamus

relay station for sensory info

Diencephalon: hypothalamus

controls: temperature, hinger, thirst, hormones

pituitary gland hangs from it

Diencephalon: epithalamus

contains pineal gland and controls sleep

brain stem: midbrain

vision + hearing reflexes

brain stem: pons

helps breathing

brain stem: medulla oblongata

controls: heartbeat, breathing, and blood pressure

cerebellum

controls: balance, posture, and coordination

multiple sclerosis

myelin destroyed —→ slower impulses

hydrocephalus

to much fluid in brain

parkinson’s disease

tremors, slow movement

alzheimer's disease

memory loss

Huntington’s disease

uncontrolled movements

stroke

blood flow blocked to brain

spina bifida

spinal cord doesn’t close fully

meningitis

meninges infected

cerebral palsy

affects muscles control

concussion

brain shaken

contusion

brain shaken

layers of meninges

from outer to inner:

dura mater

arachnoid mater

pia mater

DAP

type of neuroglia: astrocytes

support neurons

type of neuroglia: microglia

immune defense

type of neuroglia: oligodendrocytes

make myelin in CNS

type of neuroglia: Schwann cells

make myelin in PNS

what do neuroglia cells do

they support, protect, and nourish neurons

what does a blood-brain barrier allow

oxygen, glucose, and water

what does a blood-brain barrier block

toxins, many drugs, and bacteria

what is cerebrospinal fluid (CSF)

clear fluid around brain and spinal cord

where is cerebrospinal fluid (CSF) located

ventricles and around CNS

what is cerebrospinal fluid (CSF) functions

cushions brain, protection, and to carrie nutrients