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Natalia Gomez-Period 5-Nervous System - Coggle Diagram
Natalia Gomez-Period 5-Nervous System
Major Functions of the nervous system
Nervous system is master controlling and communicating system of body
• Cells communicate via electrical and chemical signals
– Rapid and specific, almost immediate responses
• Nervous system has three overlapping functions
Sensory input
Information gathered by sensory receptors about internal and external changes
Integration
Processing and interpretation of sensory input
Motor output
Activation of effector organs (muscles and glands) produces a response
Major division and subdivisions of the nervous system
Central nervous system (CNS)
Brain and spinal cord of dorsal body cavity
Integration and control center: Interprets sensory input and dictates motor output
– Peripheral nervous system (PNS)
The portion of nervous system outside CNS
Consists mainly of nerves that extend from brain and spinal cord
– Spinal nerves to and from spinal cord
– Cranial nerves to and from brain
Tissues
Nervous tissue histology
• Nervous tissue consists of two principal cell types
– Neuroglia (glial cells): small cells that surround and wrap delicate neurons
– Neurons (nerve cells): excitable cells that transmit electrical signals
Classification of neurons
Structural classification
– Three types grouped by number of processes
Multipolar: three or more processes (1 axon, others dendrites)
– Most common and major neuron type in CNS
Bipolar: two processes (one axon,one dendrite)
– Rare- example: retina and olfactory mucos
Unipolar: one T-like process (two axons)
– Also called pseudounipolar
Connection tissue coverings
The outermost connective tissue surrounds the entire muscles . The connective tissue is known as perimysiam and the innermost sheath surrounds the individuals muscle fiber .
Major parts and functions of the brain
Cerebrum—that interpets sounds, taste, and touch . It regulates emotions, learning and reasoning.
Cerebellum- maintains balance, osture, coordination and fine motor skills.
Brain stem- It regulates many automatic body functions.
Major parts and functions of the spinal cord
Functions
– Provides two-way communication to and from brain and body
– Major reflex center: reflexes are initiated and completed at spinal cord
Two lengthwise grooves that run length of cord partially divide it into right and left halves
– Ventral (anterior) median fissure
– Dorsal (posterior) median sulcus
Gray matter and spinal roots
– Cross section of cord resembles butterfly or letter “H”
– Three areas of gray matter are found on each side of center and are mirror images:
Dorsal horns: interneurons that receive somatic and visceral sensory input
Ventral horns: some interneurons; somatic motor neurons
Lateral horns (only in thoracic and superior lumbar regions): sympathetic
neurons
Cranial Nerves
12 pairs of cranial nerves are associated with brain
Two attach to forebrain, rest with brain stem
Most are mixed nerves, but two pairs purely sensory
Olfactory nerves
– Sensory nerves of smell
– Fibers synapse in olfactory bulbs
Optic nerves
– Arise from retinas; really a brain tract
– Pass through optic canals, converge, and partially cross over at optic chiasma
Oculomotor nerves
– Fibers extend from ventral midbrain through superior orbital fissures to four of six
extrinsic eye muscles
Trochlear nerves
– Fibers from dorsal midbrain enter orbits via superior orbital fissures to innervate
superior oblique muscle
Trigeminal nerves
– Largest cranial nerves; fibers extend from pons to face
Trigeminal nerves
– Largest cranial nerves; fibers extend from pons to face
Abducens nerves
– Fibers from inferior pons enter orbits via superior orbital fissures
Facial nerves
– Fibers from pons travel through internal acoustic meatuses and emerge through
stylomastoid foramina to lateral aspect of face
– Chief motor nerves of face with five major branches
– Motor functions include facial expression, parasympathetic impulses to lacrimal
Vestibulocochlear nerves
– Afferent fibers from hearing receptors (cochlear division) and equilibrium receptors
(vestibular division) pass from inner ear through internal acoustic meatuses and
enter brain stem at pons-medulla border)
Glossopharyngeal nerves
– Fibers from medulla leave skull via jugular foramen and run to throat
– Motor functions: innervate part of tongue and pharynx for swallowing and provide
parasympathetic fibers to parotid salivary glands
Vagus nerves
– Only cranial nerves that extend beyond head and neck region
– Fibers from medulla exit skull via jugular foramen
Accessory nerves
– Formed from ventral rootlets from C1 to C5 region of spinal cord (not brain)
– Rootlets pass into cranium via each foramen magnum
Action potential and Nerve Impulse
Occur only in muscle cells and axons of neurons
• Brief reversal of membrane potential with a change in voltage of 100 mV
• Action potentials (APs) do not decay over distance as graded potentials do
• In neurons, aka nerve impulse
• Involves opening of specific voltage-gated channels
Spinal Nerves
31 pairs of spinal nerves
•All are mixed nerves named for point of issue from spinal cord
They supply all body parts except head and part of neck
– 8 pairs of cervical nerves (C1–C8)
– 12 pairs of thoracic nerves (T1–T12)
– 5 pairs of lumbar nerves (L1–L5)
– 5 pairs of sacral nerves (S1–S5)
– 1 pair of tiny coccygeal nerves (C0)
Neurotransmitters
ANS: pathway uses a two-neuron chain
Preganglionic neuron: cell body in CNS with thin, lightly
myelinated preganglionic axon extending to
ganglion
Postganglionic neuron cell
body synapses with preganglionic axon in
autonomic ganglion with nonmyelinated
postganglionic axon that extends to effector organ
Compare & contrast the autonomic nervous system
The somatic nervous system consists of nerves that go into the skin and muscle involved in conscious activities. The automatic system consist of nerves that connect to the CNS to the visceral organs such as the heart, stomach and intestines.
Both the somatic and automatic nervous system are two components of the peripheral nervous system.
Reflex arc (major parts & functions)
Effector: muscle fiber or gland cell that responds to efferent impulses by contracting or secreting
Motor neuron: conducts efferent impulses from integration center to effector organ
Integration center: either monosynaptic or polysynaptic region within CNS
Sensory neuron: transmits afferent impulses to CNS
Receptor: site of stimulus action
Components of a reflex arc
Disorders/Diseases
Cerebrovascular-occurs when blood flows to a portion of the brain beheld. It causes diabetes, high cholesterol and increasing ages. The symptoms are severe headaches, and confusion or memory loss.
Autism-Brain disorder makes it difficult to communicate. The causes are family history and mostly to males. Symptoms are delay in learning and anxiety or depression.
Alzheimer’s- A form of dementia associated with age. It’s causes are injury or disease. Symptoms are memory loss or confusion.
Spinal cord-Damage to the spinal cord. It causes direct injury or disease. Symptoms are weakness or loss of feelings below.
Meningitis- An infection in meningitis surrounding the brain. It causes bacteria or viral infection. The symptoms are nausea and vomit.
Multiple Sclerosis- Autommune disease that damages myelin. It causes hereditary or family history. The symptoms are muscle weakness or depression.
Drugs of abuse (Mouse Party)
Heroine-dopamine and serotonin excites serotonin neurons at a higher area and is used for painkillers.
Ecstasy-serotonin which MDMA can cause a greater release of serotonin and horepirephine.
Marijuana-Clopamine nuerotransmitter the THC stimulates the neurons to release a signing chemical.
Methamphetamine-Dopamine which any excess dopamine will become trapped in synaptic.
Alcohol-GABA which reduces production of GABA in brain throughout the body and impulses control and memory formation.
Cocaine-dopamine which cocaine blocks transporter, leaving dopamine trapped which leaves it unable to be still.
LSD-serotonin receptors to then LSD may inhibit and may excite them. This helps with relaxation.