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Nervous System- Alejandro Alvarez P2 - Coggle Diagram
Nervous System- Alejandro Alvarez P2
Nervous System Divisions
Central Nervous System (CNS)
Function: responsible for integration and decision making.
Structure: made up of brain and spinal cord
Characteristics: enclosed in bony structures (skull and vertebrae) making it difficult to access.
Peripheral Nervous System (PNS) (consists of cranial & spinal nerves)
Autonomic Nervous System (connects CNS to viscera, and controls subconscious activity)
Sympathetic
Function: prepares body for fight or flight siuuations
Target Organs: heart, lungs, joints, stomach, eyes
Characteristics: short preganglionic fibers arise from gray matter in thoracic/lumbar region of spinal cord. Axons leave spinal nerves and enter into the sympathetic ganglia where they. synapse with postganglionic neurons.
Parasympathetic
Functions: active under normal condidtions such as rest and digestion.
Target organs: salivary glands, esophageal glands, gastric glands, pancreas.
Characteristics: long preganglionic fibers arise from brainstem and sacral region of spinal cord. The fibers extend to cranial and sacral nerves where they synapse in terminal ganglia. Short postganglionic fibers continue to effector.
Somatic Nervous System
connects CNS to skeletal muscles and the ski, and oversees conscious activities.
Cranial Nerves (12)
I Olfactory
Type: Sensory
Function sense of smell
II Optic
Type:Sensory
Function: sense of vision
III Oculomotor
Type: Primarily Motor
Function: move eyelids, eyes, focus lenses, light in the eyes
IV Trochlear
Type: primarily motor
Function: moves eyes in all directions
V Trigeminal
Maxillary division
Type: mixed
Function: upper teeth, upper gum,, upper lip, linning of palate, and skin of face
Mandibular division
Type: mixed
Function: sensory fibers conduct impulses from skin of jaw, lower of jaw, teeth, upper gum, and lower lip. Motor fibers conduct impulses to muscles of mastication and floor of mouth.
Ophthalmic division
Type: miixed
Function: surface of eyes, scalp, forehead, and upper eyelid
VI Abducens
Type: primarily motor
fucntion: move eyes laterally
VIII Facial
Function: Sensory fibers conduct a sense of taste. Motor fibers impulse muscles of facial expressions, tear glands, and salivary glands.
Type: Mixed
VIII Vestibulocochlear
Cochlear branch
Type: sensory
Function: sense of hearing
Vestibular branch
Type: sensory
Function: balance and equalibrium
IX Glossopharyngeal
Type: mixed
Function: conduct impulses from pharynx, tonsils, posterior tongue, and carotid arteries
X Vagus
Function: somatic motor fibers help with speech and swallowing. Sensory fibers conduct impulses from pharynx, esophagus, and viscera from thorax and adbdomen.
Type: mixed
XI Accessory
spinal branch
Type: motor
motor fibers help move back and neck
Cranial branch
Function: motor fibers help with soft palate pharynx and larynx.
Type: primarily motor
XII Hypoglossal
Type: primarily motor
Function: muscle fibers help move tounge
Neurotransmitters
PNS
Acetylcholine
.stimulates skeletal muscle contraction at the neuromuscular junction, may excite or inhibit autonomic nervous system actions depending on receptors.
Dopamine
Limited actions in the autonomic nervous system; may excite or inhibit, depending on receptors.
(sympathetic) Norepinephrine
sympathetic postganglionic fibers release norepinephrine in fight or flight situations.
(sympathetic) epinephrine
released during fight or flight situations.
CNS
Acetylcholine
. controls skeletal muscle actions
Dopamine
creates a sense of feeling good; deficiency in areas of the brain can lead to Parkinson disease.
Serotonin
. leads to sleepiness, action is blocked by LSD, enhanced by selective serotonin reuptake inhibitor drugs.
Histamine
. promotes alertness, released in hypothalamus.
General Functions
Sensory
Detects internal and external change.
characteristics: provided by sensory receptors, information travels from receptors to sensory neurons which transports information into the CNS.
Integrative
Function: Coordination of sensory information in the CNS
Characteristics: processing of information is the basis for decision making.
Motor
Functions: reponds to decisons made in the CNS
Characteristics: Nerve impulses are conducted along motor neurons to effectors
The Brain
Cerebrum
Surface
Gyri
Ridges located throughout cerebrum and cerebellum
Sulci
Structure: grooves
Location: Central sulcus (separates frontal and parietal lobes), lateral sulcus (separates temporal lobe and parietal lobe)
Fissures
Structure: deep grooves
Location: divides the cerebral hemispheres (longitudinal fissure), divides the cerebrum from cerebellum (transverse fissure)
Lobes
Temporal (sides)
Functional Areas
Auditory/hearing senses (posterior), sense of smell (deep in temporal lobe)
Association areas
Wernickes area (left side) helps with understanding written and spoken language.
Frontal (front)
Association Areas
controls planning and problem solving.
Functional Area
Broca's motor speech area controls muscle movements for speech.
Parietal (top)
Functional Areas
Cutaneous Senses
Association areas
function in understanding speech and choosing proper words
Occipital (back)
Functional Areas
Visual senses.
Association Areas
help analyze visual patterns and combine visual images with other sensory info.
Matter
White Matter
Structure: made up of myelinated nerve fibers connecting cell bodies of the cerebral cortex with the rest of the nervous system
Location: lies beneath the cerebral cortex
Cerebral Cortex (Gray matter)
Location: Lies on the outside of the cerebellum.
Structure: contains 75% if the neuron cell bodies in the nervous system.
Basal Nuclei
Structure: masses of gray matter
Function: help facilitate voluntary movement
altered activity of these nuclei neurons produces the signs of Parkinson and Huntington Disease.
Ventricles (connected cavites filled with cerebrospinal fluid)
Lateral (1st and 2nd)
3rd Ventricle
4th ventricle
Cerebral aqueduct
Corpus Callosum
Structure: flat bundles of nerve fibers that connect the hemispheres
Cerebellum
Cerebellar cortex
layer of thin gray matter that lies outside of the arbor vitae.
Arbor Vitae
core of white matter that branches like a tree
Function: integrates sensory info about the position of body parts, coordinates skeletal muscle activity, maintains posture
Characteristics:located beneth occipital lobes of cerebrum, made up of 2 hemispheres connected by vermis, communicates through cerebellar peduncles
Diencephalon
Thalamus
. sorts and directs sensory info. to cerebral cortex, channels sensory impulses, except sense of smell. produces awareness such as pain, touch, and temperature.
Hypothalamus
produces hormones that cause pituitary gland to secrete its hormones, regulates heart rate, body temp, sleep, wakefullness, and digestive tract.
Limbic System
. controls emotional experience and expression. Modifies behavior by producing feelings of fear, anger, pleasure, and sorrow.
Brainstem
Midbrain
Location: between the diencephalon and pons
Function: contains main motor pathways between cerebrum and lower portions of the nervous system
Pons
Location: between midbrain and medulla oblongata.
Function: contains centers that regulate the rate and depth of breathing
Medulla Oblongata
. transmits ascending and descending impulses between brain and spinal cord. houses nuclei that control visceral functions:
Cardiac Center
alters heart rate
Vasomotor Center
controls vasoconstriction and vasodilation of blood vessels, helps control blood pressure
Respiratory Center
controls rate and depth of breathing
Spinal Cord
Structure
Cervical Enlargement
thickened area near top of spinal cord, provides nerves to upper limbs
Lumbar enlargement
thickened area near bottom of spinal cord, provides nerves to lower limbs
Cauda Equina (horse's tail)
structure where spinal cord tapers to a point inferiorly, consists of spinal nerves in the thoracic and sacral regions
Meninges
Dura Mater (outermost), dense connective tissue, sheath around spinal cord is seperated by epidural space from vertebrae.
Arachnoid Mater (middle layer)
Subarachnoid Mater (in between pia and aracnoid) contains cerebrospinal fluid.
Pia Mater (Innermost layer)
Function
Ascending tracts
carries sensory information to the brain
Descending Tracts
carries motor information from brain to muscles of glands
Spinal Reflexes:
controlled by reflex arcs that pass through the spinal cord.
Spinal Nerves (31)(8 cervical, 12 thoracic, 5 lumbar, 1 coccygeal)
Brachial Plexuses (C5-T1)
arise from lower cervical and thoracic nerves, supply muscles and ksin of arms, forearms, and hands. upper limbs, include ulnar, median, radial, and axillary nerves
Cervical Plexuses (C1-C4)
lie on either side of neck, supply muscles and skin of neck, include phrenic nerves which controls diaphragm.
Lumbosacral Plexuses (L1-S4)
arise from lower spinal cord, supply muscles of abdomen skin, external genitalia, buttocks, legs, include obturator, femoral, and sciatic nerves.
Classification of Neurons
Functional
interneuron
.multipolar, lies within CNS, forms links between other neurons
Motor neuron
multipolar, conduct impulses from CNS to peripheral effectors (muscles or glands)
Sensory Neuron
.usually unipolar, conduct impulses from PNS to CNS
Structural
Multipolar
.many dendrites and 1 axon (most are in CNS)
Bipolar
2 processes extending from cell body, a dendrtie and an axon, found in special senses such as eyes, ears, and nose
Unipolar
have 1 process extending from cell body, outside cell body it splits into 2 parts that work as 1 axon
Tissues
Neurons
Structure
Soma
cell body, contains major organelles such as nucelus
Dendrite
conducts impulses TO cell body.
Axon
conducts impulses AWAY from cell body
Myelin sheath
increase conduction speed of axon, contains gaps called nodes of Ranvier
Function
cells that communicate via electrical impulses, with neurons
Neuroglia
Function
support neurons, fill spaces, protect, insulate
PNS
Schwann Cells
myelin producing neuroglia
Satellite cells
protective covering around cell bodies of neurons in the PNS
CNS
Microglia
small cells that are phagocytes for bacterial cells and produce scar tissue in sites of injury.
Oligodendrocytes
form myelin sheath around axons in brain and spinal cord.
Ependymalcytes
produce cerebrospinal fluid
Astrocytes
structural support for blood vessels and neurons, formation of blood
Connective Tissue Coverings
Epineurium
outer covering of a nerve (superficial)
Perineurium
Covering around fasicles (bundles of nerve fibers)
Endoneurium
covering around indivigual nerve fibers (axons)
Action potential and Impulse conduction
Action potential steps
Now, both inside and outside of cell are positive (depolarization
when at threshold potential Na+ channels open changing charge to +30 mv (action potential)
Potential changes from -70mv to -55mv.
outward flow of K+ ions allow the cell to become negative again (repolarization)
stimulus opens Na+ channels allowing Na to enter the cell making it less negative
After repolarization, hyperpolarization occurs where potential falls to -77mv
Neuron remains rested
Finally the Na/K pump moves Na out of the cell and K back in
After action potential is finished, cells return to resting potential
Types of Impulse Conduction
Continous Conduction
Occurs in unmyelinated axons, conducts impulses sequently over the entire length of their membrane
Saltatory Conduction
occurs in myelinated axons, myelin sheath insulates axon, impulses jump from one node of ranvier to the next.
Disorders/Diseases
Cerebroascular Accident (stroke)
Symptoms: severe headache, confusion/memory loss, change in alertness
Treatment: hospitlization, blood thinners, surgery,
Causes/Risk factors: blood vessels burst, diabetes, high cholestral
Autisum (erratic behavior non communative)
Causes/Risk factors: hereditary, environmental, post medical issue
Symptoms: delay in learning, anxiety, depression
Treatment: anxiety management, medication, therapy.
Alzhimers Disease (form of dimentia with old age)
Symptoms: memory loss, confusion, mood swings
Treatment: uncruable, medication, stem cells
Causes/Risk factors: hereditary, head tramua, family history
Spinal Cord Injury
Symptoms: paralysis, pain, numbness
Treatment: surgery, bed rest, phys. therapy
Causes/Risk factors: direct injury, disease, assult
Meningitis (affects meninges on brain)
Symptoms: nausea, vomiting, severe headache
Treatment: antibiotics, medication, vaccine
Causes/Risk factors: bacterial infection, tumors, fungi
Multiple Sclerosis (autoimmnune disease, damages myelin sheath
Causes/Risk factors: hereditary, family history
Symptoms: muscle weakness, vision loss
Treatment: steroids, phys. therapy
Drug Abuse
Methamphetamines
Neurotransmitter Affected: Dopamine
Description: meth mimics dopamine which allows it to be transported into the cell using dopamine receptors. As meth is entering the cell, its removing dopamine into the cleft which allows it to bind again to the receptors, overstimulating the cell.
Sensation: intense pleasure and exhilaration
Alcohol
Neurotransmitter Affected: GABA
Description: Alcohol makes GABA receptors even more inhibitory and binds to glutamine receptors preventing glutamine from exciting the cell.
Sensation: affects decison making, and impulse control
Marijuana
Neurotransmitter Affected: Dopamine
Description: Cannaboid binds to receptors which turns off the release of inhibitory neurotransmitters allowing dopamine to be released. THC mimmics this allowing dopamine to squirt through into the synapse.
Sensation: calm, relaxed
Cocaine
Neurotransmitter Affected: Dopamine
Sensation: makes user feel fidgety and unable to be still
Description: cocaine blocks dopamine transporters that remove it from synaptic cleft which allows it to bing again and again, over stimulating the cell.
Ecstacy
Neurotransmitter Affected: Serotonin
Description: confuses receptors for serotonin and acts like serotonin
Sensation: mood, sleep, perception, and appetite
LSD
Neurotransmitter Affected: Serotonin
Sensation: wakefulness, and evoking a startle to unexpected stimulus.
Description: LSD chemically resembles serotonin and elicits its effect by binding to serotonin receptors
Heroine
Neurotransmitter Affected: Dopamine
Description: heroin mimics natural opiates and binds to opiate receptors allowing dopamine to be replaced
Sensation: sedation, and well being