Nervous System Imogen Ecal Period 1

Major Functions of the Nervous System

Major Divisions & Subdivisions of the Nervous System

Tissues

Classification of Neurons

Connective Tissue Coverings

Major Parts & Functions of the Brain

Major Parts & Functions the Spinal Cord

Action Potential & the Nerve Impulse

Cranial Nerves

Neurotransmitters

Compare & Contrast Autonomic Nervous System

Reflex Arc

Disorders Associated with Nervous System

Drugs

MDMA: AKA ecstasy, causes increase of energy and distortion of perception; feeling of euphoria; interferes with body temperature regulation; when taken in large amounts, they can cause panic attacks

Nicotine: Cigars, cigarettes, vaping; highly addictive but is bad for the body; can be taken through smoking, nicotine patches; stimulant, can be relaxing to users

Inhalents: Not drugs, they're household products; it can cause hallucinations, brain damage, and impair coordination

Psychedelics: Hallucinogen; causes hallucinations and distortions; causes users to sense things that are not there, intensifies emotions and senses

Dissociative Drug: Feeling of detachment; causes hallucinations and distortions; lose touch with reality for users

Opioids: Used for pain relief; same category as morphine; when injected, they can cause pinpoint pupils and which is followed by a period of drowsiness and clouded thinking

Ecstasy: Mimics serotonin and can lead to addiction

Heroine: Binds to opiate receptors; feeling of sedation and well being

Marijuana: Users feel relaxed and calm from slowed down movements

Methamphetamine: Mimics dopamine and is highly addictive; works with the brain's reward pathway

Alcohol: Causes users to be disoriented and make bad decisions

Cocaine: Users are fidgety; also works in the brain's reward pathway and is addictive

LSD: Users are more aware and easily startled

Meninges

Dura Mater: outermost layer; tough

Arachnoid Mater: string like; between dura mater and pia mater

Pia Mater: innermost layer; looks like saran wrap; clear and thin

Integration Center: monosynaptic or polysynaptic

Motor Neuron: conducts efferent impulses from integration center to effector organ

Sensory Neuron: transmits afferent impulses to CNS

Effector: muscle fiber or gland; responds to efferent impulses by contracting or secreting

Receptor: site of stimulus action

Response: ex. muscle contraction

Stimulus: ex. stimulus on skin

Cerebellum: between cerebrum and brain stem; helps in coordination and movement related to motor skills

V. Trigeminal Nerves: largest nerve, motor & sensory function

VI. Abducens Nerves: Helps move the rectus muscle; eye movement

IV. Trochlear Nerves: responsible for movement of the eye

VII. Facial Nerves: has both motor & sensory functions

III. Oculomotor Nerves: responsible for muscle movement in the eyes

VIII. Vestibulocochlear: responsible for balance

IX. Glossophangeal Nerves: both motor and sensory functions

X.Vagus Nerves: motor, sensory, and parasympathetic functions

II. Optic Nerves: responsible for vision

XI. Accessory Nerves: provides motor function to some muscles in the neck

XII. Hypoglossal Nerves: supplies tongue muscles

I. Olfactory Nerves: responsible for a person's sense of smell

Peripheral Nervous System

Central Nervous System

Pituitary Gland: controlling growth and development and the functioning of the other endocrine glands

Olfactory Bulbs: responsible for sense of smell

Optic Chiasma: aids in vision; X shape

Huntington's Disease: inherited disorder that causes neurons in parts of the brain to gradually break down and die; affects both men and women around the ages 30-50, but can start earlier

Parkinson's Disease: progressive nervous system disorder that affects movements, present in both men & women, 50% more present in women

Multiple Sclerosis: autoimmune disease; myelin sheaths in CNS destroyed by immune system, makes them hard. Those affected will have a hard time moving, the feeling of weakness, and loss of muscle control; drugs that modify the immune system will help.

Parasympathetic Division: maintenance functions & conserves energy

Sympathetic Division: Mobilizes body during activities

Dual Innervation: all visceral organs served by both divisions

Fight-or-Flight System

fibers originate in thoracis & lumbar region

preganglionic nerves short

preganglionic fibers long

preganglionic nerves long

fibers originate from brain stem

Rest-and-Digest System

postganglionic fibers short

ganglia near visceral effector organs

ganglia close to spinal cord

more complex & innervates more organs

Motor Neurons

Interneurons

Sensory Neurons

Ventricles: empty spaces in brain filled with cerebral spinal fluid (CSF); lateral ventricle, fourth ventricle, third ventricle, cerebral aqueduct

Cross Sectional Anatomy

integration: processing and interpretation of sensory input

motor output: activation of effector organs (muscles & glands) = response

sensory input: info about internal and external changes gathered by sensory receptors

classified by chemical structure & function

language of the nervous system

Spinal Nerves

31 paired roots

5 lumbar nerves

5 sacral nerves

12 thoracic nerves

1 coccygeal nerves

8 cervical nerves

Generated

lie between sensory and motor neurons

impulses from CNS to receptors

impulses from sensory receptors to CNS

unipolar; cell bodies located in ganglia in PNS

most abundant in body

  1. depolarization: Na+ channels open
  1. resting state: gated Na+ & K+ channels closed
  1. repolarization (returns to resting membrane potential): Na+ channels inactivate, K+ channels open
  1. hyperpolarization: some Ka+ channels open & Na+ channels reset

AP happens all or none

Depolarization doesn't guarantee generation of AP

Propagation allows AP to be transmitted from origin down entire axon length toward terminals

refractory period: neurons cannot trigger AP

Diencephalon:

Brain Stem

Cerebrum (Cerebral Hemispheres)

Pons: motor function, sensation, eye movement, hearing, taste

Medulla Oblongata: transmitting signals between the spinal cord

Midbrain: movements of the eye, and in auditory and visual processing

Frontal Lobe: front of the brain; attention, planning, decision making

Parietal Lobe: touch, taste, hearing

Temporal Lobe: memory processing, emotions

Occipital Lobe: back of the brain; aids in vision

Thalamus: relay station for information coming into cortex

Hypothalamus: main visceral control and regulating center; vital for homeostasis

Wernicke's Area: involved in understanding spoken and written words

Broca's Area: motor speech area; directs muscles of speech production

brain

spinal cord

Connective Tissue Coverings

motor (afferent) division

sensory (efferent) division

autonomic nervous system (involuntary)

somatic nervous system (voluntary)

sympathetic: mobilizes body during activity

parasympathetic: maintenance functions, conserves energy

spinal nerves to and from spinal cord

cranial nerves to and from brain

innervation; visceral organs served by both divisions; dynamic antagonism

perineurium: coarse connective tissue, bundles fibers into fascicles

epineurium: tough fibrous sheath around all fascicles to form nerve

endoneurium: loose connective tissue; encloses axons and myelin sheaths (schwann cells)

Information transfer across synaptic cleft

  1. the entry of Ca2+ causes synaptic vesicles to release neurotransmitters
  1. neurotransmitters diffuse across synaptic cleft and binds to specific receptors on postsynaptic membrane
  1. graded potential is made when neurotransmitters bind to ion channels
  1. neurotransmitter effects terminated
  1. voltage-gated Ca2+ channels open, Ca2+ enters axon terminal
  1. AP arrives at axon terminal of presynaptic neuron

Gross Anatomy

Epidural space: cushion of fat & veins in the space between vertebrae and spinal dura mater

Filum terminate: fibrous extention of conus covered with pia mater & anchors to spinal cord

Denticulate ligaments: extensions of pia mater that secure cord to dura mater

spinal nerves: attach to spinal cord by 31 paired roots

Cauda Equina: collection of nerve roots at inferior end of vertebral column

ventral (anterior) median fissure

dorsal (posterior) median fissure

central canal: runs down length of spinal cord, filled with cerebral spinal fluid (CSF)

gray matter located in core and white matter located outside

dorsal horns: interneurons that receive somatic and visceral sensory input

ventral horns: some interneurons; somatic motor neurons

lateral horns: sympathetic neurons

Nervous Tissue

found in spinal cord, brain, and in nerves

Dendrite: receives input

Nucleus:

Axon: conducting region of neuron

Axon Terminal: region that secretes neurotransmitters

Schwann Cells: form myelin sheaths

Cell Body: genetic information, maintains the neuron's structure, and provides energy to drive activities

Alzheimer's Disease: results in dementia (key proteins misfolded and malfunctioned; caused by brain cells dying which makes the brain shrink

Pineal Gland: internal clock

Mamillary Body: recollective memory

gray matter

white matter

found in brain and spinal cord

found in brain and spinal cord

myelinated axons

short, nonmyelinated neurons and cell bodies

Nodes of Arnvier: in between axons

myelin sheath: composed of myelin and surrounds the axon to increase speed

Neuroglia

neuroglia (glial cells): wrap and surround delicate neurons

neurons (nerve cells): transmit electrical signals

astrocytes: most abundant and versatile, supports neurons, plays a role in exchanges between capillaries and neurons

microglial cells: small cells with thorny processes that touch and monitor neurons

ependymal cells: range in shape (squamous to columnar) may be ciliated, lines central cavities of brain and spinal column

oligodendrocytes: branched cells, processes wrap CNS nerve fibers into myelin sheaths in thick nerve fibers

Hemiplegia: paralysis of one side of the body; results in speech and sensory deficits

Meningitis: inflammation of the meninges

corpus callosum: ensures both sides of the brain can communicate and send signals to each other

fornix: cognition and episodic memory recall

Part of the parasympathetic nervous system

controls most functions of the body and mind

Epithalamus: forms roof of 3rd ventricle and contains the pineal gland

arbor vitae: white matter in cerebellum (tree shaped)

Epileptic seizure: flood of electrical discharges by groups of neurons, prevents other messages from getting through

Hydrocephalus: water on brain; increased pressure from CSF being blocked from circulating and being drained

Contusion: permanent brain damage

Concussion: temporary brain damage

Subdural or subarachnoid hemorrhage: pressure from blood may force brain stem through foramen magnum = death

cerebral edema: swelling of brain from traumatic head injury

stroke: caused by interruption of blood flow to brain

Ischemia: inadequate blood supply = death of tissue

2 way communication to and from the brain

(ALS) Lou Gehrig's Disease: destruction of ventral horn motor neurons and fibers of pyramidal tract;
loss of ability to speak, swallow, and breathe

Cerebral Palsy: neuromuscular disability involving poorly controlled or paralyzed voluntary muscles

Anencephaly: cerebrum and parts of the brain never develop; death after birth

Spina Bifida: incomplete formation of vertebral arches; caused by lack of folic acid

hypertension: high blood pressure; heart works harder; more prone to wear and tear

Raynaud's disease: fingers turn pale; painful in toes and fingers

Autonomic dysreflexia: life threatening; blood pressure rises which increases risk of stroke

controls internal environment to maintain homeostasis

voluntary movement