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Emily Hernandez Period One: Nervous System, image, image - Coggle Diagram
Emily Hernandez Period One:
Nervous System
Major Functions of the nervous system
The nervous system's function is to act as the primary controlling and communication system in the body. It is the center of all mental activity including thought, learning, and memory. The nervous system is repsonisble for memory and learning; volunatary movement as well as involuntary movement such regulating digestion.
Compare and contrast autonomic nervous system. Autonomatic nervous system consists of motor neurons that Innervate smooth muscles, cardiac muscle and glands. This involuntary control. The somatic nervous system consists of neurons that innervate skeletal muscles which are voluntary. The Parasympathetic division promotes maintenance functions and conserves enegery. The Sympathetic division mobalizes body during activity. Dual innervation is when all vitceral organs are served by both divisions. but their divisions cause opposite effects.
Role of Parasympathetic division: Is the rest-and-digest system. Keeps body energy use as low as possible even when carrying maintanence activites; directs digestion, diursis, defecation. Regulates blood pressure, heart rate and respiratory levels are low. Gastrointestinal tract activity is high. Pupils are constricted and lenses are accommodated for close vision.
Role of Sympathetic division: Is the fight or flight system. Mobilizes body during activity, Exercise, excitement, emergency, embarrassment activates the sympathetic divison; increased heartrate; dry mouth; cold, sweaty skin; dialated pupils. During rigorous activity the sympathetic divsion shunts blood to skeletal muscles and heart, dialates bronchioler and causes liver to release glucose.
Classification of neurons
Structural: 3 types of grouped by number of processes
Bipolar: 2 processes (1 axon, 1 dendrite) This is rare and found in retina and olfactory mucosa
Unipolar: one T-like process (2 axons) Aka pseudounipolar
Multipolar: 3 or more processes (1axon other dendtrites). This is the most common and major in the CNS
Functional: 3 types grouped by direction of nerve impulse travels relative to CNS
Motor: carry impulses from CNS to effectors; multipolar. Most cell bodies are located in CNS. (except some autonomic neurons
Interneurons: shuttle signals though CNS pathways. AKA asspciation neurons. Between motor and sensory neurons. Most are entirely within CNS. 99% of the body's neurons are inteneurons.
Sensory: Transmit impulses from sensory receptors toward CNS. Almost all of these are unipolar. Located in Ganglia in PNS
Drugs
Cocaine interferes with dopamin neurotransmitters and since it is concentrated in the reward pathway it causes pleaure and has the user be figedy and unable to stay still.
Marijuana mimics anadamide and binds to cannabinoid receptors which results in inhibitation to be turned on and for dopamine to squirt into the synapse. The perosn who takes this drug will have more slowed movements which has them feeling relaxed and calmed.
Psychedelics also known as DMT, LSD and magic mushrooms are hallucinogen type drugs and can be taken by swallowing, snorting, injecting, or smoking. They are a class of drugs that cause hallucinations and other distortions of pereception. They intensify sensations and emotions. They cause users to hear see and feel things that are not real. Can cause increased blood pressure and rate.
The drug heroin interferes with the inhibition neurotransmitter and it mimics natural opiates and binds to opiate receptors which truns off dopamine inhibition. As a result, dopamine is allowed to flood into the synapse. The dopmine that floods into the synapse produces immediate feelings of sedation and well being. It reduces pain as our body's opiates are natural pain killers.
LSD acts almost excusively on serotonin neurotransmiters and excites the locus coeruleus which is responisble for felling weakness and evokes a startle response to unexpected stimulus.
Dissociative drugs are also known as DXM are halluciongen type drugs and can be taken by swallowing, snorting, injecting or snorking. These drugs cause hallucinations and distortions of perception. They give feelings of detachement of the body and it's surrondings. It can cause users to loose touch with reality and behave unpredictably or violently. It can cause fevers, seizures, coma, or death.
GHB and Rohyponol are also known as Liquid X and goop. They are depresant type drugs and cause feelings of euphoria and cuase the user to black out when it is paired with alcohol. This is why GHB is known as the date rape drug.
Nicotine also know as E-cigs, darts and durries are a stimulant type of drug and can be taken by smocking, inhaling, vaping, patch, chewing or dipping. NIcotine is the active substance in tobacco plants. It increases nerve activity and heart rate. It is highly addictive and withdraw can cause cravings and difficulty sleeping.
Alchohol interacts with GABA receptors to maked them even more inhibitory and it alsi binds to glutamate receptors which prevent glutamate from exciting cell.The perosn who takes this drug is emotionally unstable and they may lose coordination and have judgement cells and remembering things.
Ecstasy affects serotonin pathways responsible for mood, sleep, perception and appetite. The exesses seratonin stimulates the release of dopamine along the award pathway giving ecstasy slightly addicting properties
MDMA also known as ecstasy and Molly is a stimulant type of drug and can be taken by swallowing or by snorting. MDMA can cause an increase in energy and distortion of perception. It causes feelings of euphoria and emotional connections to others. Other effects include involuntary jaw clenching, muscle cramping, chills and sweating. It can cause panic attacks and seizures.
Inhalents are also known as laughing gas, shappers and poppers. They are neither a depressant or a stimulant and can only be taken by inhaling the substance which is a type of chemical. It can impair coordination, speech and judgements, These substances are not designed to be used as drugs but are rather household items. They can caused hallucinations, brain damage, or sudden death.
Opioids also reffered to as narcotics are a depressant type drug that can be taken though pill, patch, snorting, injecting or smoking. They are a class of drugs similar to morphine. When is is in the body it causes a rush of warmth and of pleasure. This is then followed by a period of drowsiness and cloudy thinking. Opioids may also cause itching, nausea, and vommiting.
Methanmphetamine interferes directly with the dopamine neuorotransmitters and mimics dopamine. Since meth directly works on the reward pathway it makes the user feel intense pleasure and exhilaration.
Major Divisions and subdivisions of the nervous system
The nervous system
Central nervous system (integrative functions)
Peripheral nervous system
Sensory functions
Motor functions
Somatic nervous system; skeletal muscles and voluntary movements
Autonomic nervous system. Consists of smooth muscle, cardiac muscle and gland effectors.
Parasytmpathetic: fight or slight system.
Parasympathtic: rest and digest system
Reflex arc
The reflex arch is the neural pathway that controls a reflex. The sensory neurons do not pass though the brain but rather synapse in the spinal cord. The components of the reflex arch are the 1. Receptor which is the site of stimulus action. 2. Sensory neuron: which transmits afferent impulses to CNS. 3. Integration center: either monosynaptic or polysynaptic region w/in CNS. 4. Motor neuron: conducts efferent impulses from integratyion center to effector organ. 5. Effector: muscle fiber or gland cell that responds to efferent impulses by contracting or secreting
Reflexes are functionally classified as:
Somatic reflexes: Activate skeletal muscle
Autonomic reflexes: Activate visceral muscles (smooth or cardiac muscles or glands
Disorders associated with nervous system
Autoimmunne disease that mostly affects young adults:Multiple sclerosis. Myelin sheaths are destroyed when immune system attacks myelin. Myelin turs into hardened lesions and impulse conduction slows and eventually ceseases. The demyenlinated axons increase Na+ channels which causes cycles oif relapse and remission.
Action potential and the nerve impulse
Action potential are long distance signals of axons . Changes are used as signals to receive, integrate and send info. They are the principle way to send signals and only occur in muscle cells and axons of neurons. They do not decay over sitances and inolves the opening of specific volatge-gated channels. The four main steps for generating an action potential are resting state, depolarization, repolarization and hyperpolarization.
A nerve impulse is a signal transmitted along the axon of the nerve.When a nerve impulse reaches the end of an axon, the axon releases chemicals called neurotransmitters. Neurotransmitters travel across the synapse between the axon and the dendrite of the next neuron. Neurotransmitters bind to the membrane of the dendrite. Myelin sheaths speed up the process of the impulse traveling.
Neurotransmitters function as the body's messangerThey are the molecules used by the nervous systemto transmit messages between neurons, or from neurons to muscles. Communication between two neurons happens in the synaptic cleft This are what enter the transmitters. This is how drugs such as opioids work and they bind to opiotie transmitters.
connective tissue coverings
There are 3 different coverings of the brain. These are the dura mater, arachnoid mater and the pia mater all of which are meninges. They surround the brain and the spnial cord with their main function being to protect the central nervous system.They cover and protect CNS, protect blood vessels and enclose venous sinuses, contain cerebrospinal fluid and form divisions in the skull.
Arachnoid mater: Middle layer with weblike extensions seperated from dura mater with subdural space. The subarachnoid space contains CSF and largest blood vessels of brain.
Pia mater: Most delicate connective tissue that clings tight to brain following each convolution. The Pia mater contains many tiny blood vessels that feed the brain.
Dura mater: Most external layer and strongest meninx
Cranial nerves: to and from brain.
The twelve cranial nerves.The functions of the cranial nerves are sensory, motor, and or both: The ensory cranial nerves function to help a person to see, smell, and hear. The location of most motor cranial nerves that help control muscle movements are in the head and neck. Those function to assist with movement such as movement of facial muslces.
I. Olfactory nerve
II. Optic nerve
III. Oculomotor nerve
IV. Trochlear nerve
V. Trigeminal nerve
VI. Abducens nerve
VII. Facial nerve
VIII. Vestibulocochlear nerve
IX. Glossopharyngeal nerve
X. Vagus nerve
XI. Accessory nerve
XII. Hypoglossal nerve
Cranial nerve diagram
Major parts and functions of the spinal cord
There are three major functions of the spinal cord.
The Motor Functions - direct and comna nd the body’s voluntary muscle movements.
The Sensory Functions – monitors sensation of touch, pressure, temperature and pain and provide feeedback for object recognition.
Autonomic Functions –These are involuntary. they regulate digestion, urination, body temperature, heart rate, and blood preassure.
Spinal nerves: there are 31 pairs of spinal nerves. All are mixed nerves named for point of issue from spinal cord. They supply all parts of body except head and part of neck. Each spinal nerve is connected to the spinal cord via two roots. Both ventral and dorsal roots are branched medially as rootlets are branched medially as rootlets that then join laterally to form spinal nerve.
Ventral roots: Contain motor (efferent) fibers from ventral horn motor neurons that innervate skeletal muscles.
Dorsal roots: Contain sensory (afferent) fibers from sensory neurons in dorsal root ganglia that conduct impulses from peripheral receptors.
Major parts and functions of the brain
Adult brains have 4 regions: Cerebral hemispheres, Diencephalon, Brain stem and Cerebellum
Brain stem: Has three regions: midbrain, pons and medulla oblongata. Similar in structure to spinal cord but contains nuclei embedded in white matter. Controls automatic behaviors necessary for survival.
Medulla oblongata: Blends spinal cord at foramen magnum, contains fourth ventricle, continuation of central spinal cord, medulla and pons form ventral wall, contains choroid plexus: capillary-rich membrane that forms cerebral spinal fluid.
Functional groups of medulla oblongata
Respitory centers: generate respitory rhythm and control rate of breathing.
Various other centers regulate: vomiting, hiccuping, swallowing, coughing, sneezing
Cardiovascular center: adjusts force and rate of heart contraction, vasomotor center adjusts blood vessel diameter for blood pressure regulation
Pons: Located between midbrain and medulla oblongata. Fourth ventricle separates pons from cerebellum. Some nuclei play role in reticular formation and come help maintain normal rhythm of breathing.
Midbrain: located between diencephalon and pons.
Cerebral penduncles: 2 ventral buldes that contain pyramidal motor tracts. Form pillars that hold up cerebrum
Cerebral aqueduct: channel running through midbrain that connects 3rd and fourth ventricles.
Midbrain nuclei scattered throughout white matter include:
Corpora quadrigemina: paired dorsal protrusions
Superior colliculi: visual reflex centers
Inferior colliculi: auditory relay centers
Substania nigria: functionally linked to basal nuclei; parkinson's disease is degeneration of this area.
Cerebellum: 11% of brain mass. Located dorsal to pons and medulla. Cerebellar hemispheres connected by wormlike vermis. Contains thin cortex of gray matter w/ distinctive treelike pattern of white matter called arbor vitae. Functions of cerebellum: process information from the cortex, brain stem and sensory receptors provide precise coordinated movements of skeletal muscles. Also plays role in thinking, balance and emotion. Functions in balance and coordination
Cerebral Hemispheres: Form superior part of the brain and account for 83% of brain mass. The gyri are the ridges found in the brain, the sulci are the shallow grooves and the fissures are the deep grooves. The longitundial fissure separates the two hemispheres. The transverse fissure is what seperates the cerebellum and the cerebrum. There are four lobes with one buried under other lobes.
Lateralization: Division of labor between hemispheres, hemispheres are not identical. 90% of humans are have their left-side dominance which usually lead to right-handedness.
The left hemisphere controls language, math and logic
The right hemisphere is in charge of visual-spatial skills, intuition, emotion, and artistic and musical skill.
Ventricles: fluid filled chambers that are continuous to one another and to central canal of spinal cord. They are filled with cerebrospinal fluid and are lined with neuroglial cells.
Location: The lateral ventricles are large, C-shaped chambers that are located deep within each hemisphere. The third ventricle lies in the doencephalon and is connected to the fourth ventricale (located in hindbrain) via the cerebral aqueduct.
The Diencephalon: Consists of three paired gray-matter structures which are the thalamus, hypothalamus and the epithalamus. All three enclose the third ventricle.
Hypothalamus: Located bellow the thalamus. Forms cap over brain stem and forms inferolateral walls of third ventricle. Contains many important nuclei such as mammilary bodies and the infundibulum. The hypothalamus also controls the autonomic nervous system and initiates physical responses to emotions. The hypothalamus also regulated body temperature, regulated hunger and satiety, regulates water balance and thirst, regulates sleep wake cycle and controls endocrine system functions such as secretions of anterior pituitary gland and production of posterior pituitary hormones.
Mammilary bodies: paired anterior nuclei that act as olfactory relay stations.
Infundibulum: stalk that connects to pituitary gland.
Epithalamus: most dorsal portion of diencephalon, forms roof of 3rd ventricle, contains pineal gland, extends from posterior border and secretes melatonin that helps regulate sleep-wake cycle
The thalamus's main function if to be the relay station for incoming info to the cortex
The cortex is the executive suite of the brain and is the site of conscious mind: awareness, sensory perception, voluntary motor initation, communication, memory storage and understanding. It makes us 40% of mass of the brain. There are three types of functional areas.
Sensory areas: conscious awareness of sensation. 8 main areas: primary somatosensory cortex, somatosensory association cortex, visual areas, auditory areas, vestibular cortex, olfactor cortex, gustory cortex, and vesceral sensory area
Association areas: integrate diverse information
Motor areas: controls voluntary movement. In the frontal lobe, it acts to control voluntary movement.
Broca's area: Present in one hemisphere (usually the left). Motor speech area that directs muscles. Active in planning speech and voluntary motor activities.
Premotor cortex: located in frontal lobe anterior to the primary motor cortex. Helps plan movements and is the staging area for skilled motor activities. It controls learned, repetitious or patterned motor activities. It coordinates simultanuos motor skills and controls voluntary action that depend on sensory feedback.
Primary (somatic) motor cortex: located in precentral gyrus of frontal lobe. It's primary function is to generate signals to produce movement.
