Nervous System

functions of nervous system

sensory input, integration, motor output

the nervous system utilizes

electrical energy

astrocytes

star cell

most abundant and versatile

1. brace neurons and blood vessels

2. formation of blood brain barrier

3. hold on to glucose

4. store potassium ions

5. mop up neurotransmitters

what can cross blood brain barrier

ethanol

glucose

insulin

microglial cells

phagocytes

part of immune system

protect neurons from oxidative stress

ependymal cells

epithelial cell that does not rest upon basement membrane

line ventricles filled with cerebrospinal fluid

-cushions/protects

-cilia propel CSF

-vitamin C mops up damaging oxygen species

oligodendroctyes

form myelin sheath (insulating fat)

wrap around CNS nerve fibers

white matter vs gray matter

white matter: axons

gray matter: lacks myelin, primarily cell bodies

schwann cells

form myelin sheath in PNS

each cell wraps part of only 1 axon

acts as splint to allow regeneration for damage to PN fibers

satellite cells

-cushions/protects cell bodies

-mops up damaging oxygen species

-surround cell bodies in PNS

neuron structures

cell body: metabolic center

nissl bodies: rough ER

neurofibrils: intermediate filaments

types of sensory receptors

-pain and temp receptors: free nerve endings

-touch receptor: Meissner's corpuscle

-deep pressure receptor: Lamellar corpuscle

-proprioceptor: muscle spindle, golgi tendon organ

multipolar, bipolar, and unipolar neurons

graded potential

a shift in the electrical charge in a tiny area of a neuron

-local depolarization

ventral vs dorsal horn

anterior vs posterior

cervical plexus

C1-C5

phrenic

diaphragm, skin and muscles of shoulder and neck

damage could result in respiratory paralysis

brachial plexus

C5-C8 and T1

brachial plexus nerves

axillary, radial, median, musculocutaneous, ulnar

axillary nerve

deltoid muscle and skin of shoulder and muscles/skin of superior thorax

damage could result in paralysis or atrophy of deltoid muscle

radial nerve

triceps and extensor muscles of forearm and skin of posterior upper limb

damage could cause wristdrop

median nerve

flexor muscles, some muscles and skin of hand/fingers

damage can cause decreased ability to flex and abduct hand, thumb, and cant pick up small objects

muscultaneous nerve

flexor muscles of arm

skin of lateral forearm

damage could cause decreased ability to flex forearm at elbow

ulnar nerve

some flexor muscles of forearm, wrist, hand

damage could cause clawhand

lumbar plexus

L1-L4

lumbar plexus nerves

femoral and obturator

femoral nerve

lower abdomen and thigh muscles

damage could cause inability to extend leg and flex hip and loss of cutaneous sensation

obturator nerve

adductor muscles of thigh and small hip muscles

skin of thigh and hip and knee joints

damage could cause inability to adduct thigh

sacral plexus

L4-L5 and S1-S3

sacral plexus nerves

sciatic, common fibular, tibial, superior and inferior gluteal

sciatic nerve

lower trunk and posterior thigh

hip extensors and knee flexors

damage could cause: inability to extend hip and flex knee, sciatica

common fibular nerve

leg and superior foot

damage: foot drop

tibial nerve

posterior leg and sole of foot

damage could cause inability to plant flex and invert foot-shuffling gait

superior and inferior gluteal

gluteus muscles of hip

damage could cause inability to extend hip or rotate thigh

preganglionic neuron

CNS → Preganglionic neuron → (ACh released in ganglion) → Postganglionic neuron → Target organ

functional classifcation

sensory and motor division

motor division consists of

somatic and autonomic nervous system

somatic nervous system

controls skeletal muscle

autonomic nervous system

controls smooth/cardiac muscle and glands

autonomic division contains

sympathetic and parasympathetic

glial cells in central vs peripheral nervous system

CNS: microglia, oligodendrocytes, ependymal cells, astrocytes

PNS: Schwann cells, satellite cells

tracts

clusters of neuron cell bodies in the CNS

nerves

bundles of nerve fibers in the PNS

motor and interneurons are

multipolar

most sensory neurons are

unipolar, but some are bipolar

reflex arc

sensory receptor, sensory neuron, motor neuron, and effector that are involved in a quick response to a stimulus

gyri

Sulci (sulcus)

fissures

basal nuclei

regions of gray matter deep within white matter that modify voluntary motor activity

parkinsons and huntgions are disease of these

Diencephalon

thalamus and hypothalamus

meninges

dura mater, arachnoid mater, pia mater

CSF

formed by choroid plexuses

found in subarachnoid space, ventricles, and central canal

dorsal rami

serve the skin and muscles of the posterior trunk

ventral rami

form a complex of networks (plexus) for the anterior and limbs

parasympathetic parts

terminal ganglia are where the second motor neurons close to organ served

sympathetic parts

preganglionic neurons

ganglionic in sympathetic trunk or in collateral ganglia

postganglionic axons secrete norepinephrine

saltatory conduction

Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane.

resting potential

-70

levels that affect action potential

ATP

K

Na

Ca

the ventral root contains

axons

trapezius

Elevates, depresses, retracts, and rotates the scapula; rotates the arm

deltoid

abducts arm

rectus femoris

extends leg and flexes thigh

gracilis

adducts thigh, flexes and medially rotates leg

pectoralis major

Adducts and flexes humerus

pectoralis minor

protracts and depresses scapula

quadriceps femoris group

extends leg at knee

hamstring group

involved in knee flexion and hip extension

Sartorius

Flexes thigh on hip

longest muscle

soleus

plantar flexes foot

Gastrocnemius

plantar flexes foot

brachialis

elbow flexion

latissmus dorsi

extends and adducts humerus

intercostals

between ribs; moves ribs for breathing

Sternocleidomastoid

Rotates head side to side and flexes neck.

Platysma

Tenses skin of neck, depresses mandible.

Temporalis

Elevates and retracts mandible (chewing).

Masseter

Closes jaw, elevates mandible.